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Mineral processing plant design and optimisation


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A two hour workshop held in Sandton Johannesburg on 28 Sept 2012

Published in: Education

Mineral processing plant design and optimisation

  2. 2. CONTENTS • Plant Design and Commissioning • General Procedure for plant design • Plant Design Simulation and Optimization • Process Evaluation and control • Case Study: Real time information management infrastructure for asset optimization. • Risk and Loss Control Management • Case Study: The early stage Risk minimization in Process Flowsheet design • Process Strategy Development
  3. 3. CONTENTS…… • Equipment retrofit and Rationalization using the System Acquisition approach , • Principles and Practice of Automated control systems • The Benefits of Dynamic Simulation for the Minerals Industry • Taking mineral processing plant simulation to a new level – Inclusion of mine plan and financial performance • General • Plant Construction and Commissioning • A few general Rules • Plant Design - What not to do? • The role of innovation in Mineral Processing and Metallurgical Plant Design
  4. 4. PLANT DESIGN – PAGE 13 • General Procedure for plant design • Process Design • Flow sheet Design • Process Plant Simulation • General Arrangement Drawings • Detailed Design • Metallurgical involvement in the construction phase • Commissioning • Cold commissioning • Hot commissioning • Practical commissioning tips • Acceptance runs • Conclusions
  5. 5. Plant Design Introduction • Importance of Good Plant Design and Punctual Commissioning • A good plant design can minimize capital expenditure and maximize on long term profits. • A good plant design together with careful planning and execution of the startup can greatly contribute towards: • easing commissioning problems, • and can ensure the plant brought into production • Timorously • To Design capacity and efficiency, • And Within budget. • Delays in commissioning can prove to become an extremely costly exercise in terms of profit loss due to loss of production
  6. 6. PLANT DESIGN • General Procedure for plant design • Ore testing, • Process definition, • Production of basic flowsheet, • Production of piping and instrument drawings, • Production of general arrangement drawings and conceptual models, • Equipment selection and specification • Costing and preparation of definitive budget, • Production of final flowsheet, • Construction, • Commissioning
  7. 7. Process Design • Process design criteria • A statement of what the plant will be required to do and the framework in which it will have to accomplish it. It includes: • The capacity of the plant, • Material to be treated, • The sources of feed, • The product, • Time schedule for the commissioning of the various stages, • General information regarding the externally imposed parameters of the design • Normally prepared by the mining and financial consultants, • Deals essentially with: • What the plant is to achieve,
  8. 8. PROCESS DESIGN • Basic directive to the plant designer, • Setting limits within which they should operate, • And targets they must attain. • The design metallurgist must insist that he be given the Process design criteria as part of the essential documentation of his commissioning
  9. 9. Flow sheet Design • The flowsheet deals with the means by which the objectives are to be attained • Diagrammatic definition of how the requirements specified in the design criteria are to be achieved. • Flowsheet design is a major and vital part of process design, • The correct choice of flowsheet is crucial to the technical and financial success. • The design process • Arranging in diagrammatic form the necessary equipment, installations and interconnections to achieve the goals specified in the design criteria, • Compiling with the treatment method indicated by the laboratory analysis, • And any other source of information or requirements
  10. 10. FLOWSHEET DESIGN • Various possible alternative technical treatment routes are roughly plotted and considered • feasibility studies in terms of capital estimated are performed on each or combination of these options. • Initially only rough estimates of capital are required between -15% to + 25% • As the project progresses more accurate estimates of capital +/- 5% are required
  11. 11. QUANTIFIED FLOW SHEET • For flowsheet to be used in subsequent costing, evaluation, and design stages it must be quantified. Ie. It must include the following information • Flow streams throughput of the plant, • Equipment to be installed, • A table showing flow and equipment data, • All primary data (data on which the flowsheet is based as per design criteria and test results) • Flow rates must be based on the full length of time as specified on the design criteria, • Initial flow rates must be correct when actual running times are available • Secondary data calculations based on mass balance around the equipment must then be shown.
  12. 12. QUANTIFIED FLOW SHEET • Estimation of actual running time • Initially flow data is based on 100% running time, • Consideration must be given to the number of hours it will be manned and is planned to run, • The proportion of lost time due to random unplanned breakdowns and stoppages must also be considered. • The legal constraints of operation must also be considered, • Estimating actual running time • When the actual running time for the various equipment is estimated the initial flow rates can be corrected using the following factors: • Hours in month used for initial flowrate calculation / Estimated actual running time in the same length month for the type of machine involved.
  13. 13. QUANTIFIED FLOW SHEET The following data must also be tabulated obtained from the lab results in order to complete the flow sheet: • Size distribution, • pH, • temperatures and • Reagent concentrations • Equipment sizing and selection • The design procedures so far described have provided some of the essential data on which equipment sizing and selection can be based, • namely the flow data pertaining to each stream in the plant.
  14. 14. QUANTIFIED FLOW SHEET • The next step is to determine with the help of this data, what capacity volume or energy input is required to bring about whatever change is required in each stream, whether of position, size distribution, chemical state, moisture content, etc • there will be several combinations of available sizes and numbers of machine that will fulfil each requirement • The decision as to which is the correct combination is essentially an economic one, that is, determination of the relative profitabilities of the various alternatives. • the result of the above calculation will usually indicate that, in the case of major equipment , 'big is beautiful
  15. 15. STEADY STATE SIMULATOR • Combines the following: • A flow sheet • A phase model • A mathematical model • A set of algorithms
  20. 20. STEADY STATE SIMULATION • The following elements are combined • Flowsheet • A phase model • Raw material • Reagents • Products • Water • Waste • A mathematical model for each unit operation • A set of algorithms • For data reconcilation • Model calibration • Unit operation sizing • Full material balance calculation • Power consumption • Capital cost calculations
  22. 22. PRELIMINARY PLANT DESIGN USING SIMULATION • Assessing the Plant requirements in terms of: • Flowsheet • Stream description feed characteristics • And main performance objectives • A preliminary material balance is established by direct simulation • Which yields an ideal description of all the streams • Use reverse simulation to back calculate the dimensions of main pieces of equipment • Simulate the future plant operation and calculate the Capital investment • Compare several flow sheets in terms of technical performance and financial implications
  24. 24. ADVANCED PLANT DESIGN USING A SIMULATOR • Use material balancing techniques to reconcile all experimental data coming from sampling campaign during pilot plant test • Build a simulation of the pilot plant by calibrating each unit operation model by using coherent data • Multiply all streams by scale up factor • Back calculate the dimensions of the main pieces of equipment in industrial conditions • Simulate the future plant operations in various configurations and calculate the capital investment
  26. 26. PLANT OPTIMIZATION AND UPGRADE • Use material balance techniques to reconcile all available operating plant data • Build a simulation of the existing process plant by calibrating each unit operation model using coherent plant data • Use the simulator to test different processing scenarios and analyse the simulation results in terms of • Technical • Characteristics of product • Power drawn by main equipment • Environmental • Tailings stability • Waste minimization and • Water recycling • Economic • Estimation of capital cost investment • Reactive consumtion
  28. 28. QUANTIFIED FLOW SHEET • Plant design Computer simulator
  30. 30. PROCESS EVALUATION PAGE 60 • Two kinds of information processing are important for the effective control of metallurgical Plants • Systems for gathering and analyzing data of a long term nature for statistical and accounting purposes • Short term data required for the control of the plant. This information is analyses and action taken immediatedly.
  31. 31. PROCESS EVALUATION • The requirements for these are different • For process evaluation the primary requirement is accuracy. • Used for cost control and metallurgical accounting. • Rapid feedback is not required. • For process control rapid information is required • Reprodibility of information is important • Need for identification of changes in process parameters.
  32. 32. PROCESS EVALUATION • Components of Process Evaluation • Sampling to obtain representative data • Sample preparation, • measurement of mass flowrate • analysis of sample • analysis of data to calculate metallurgical balance.
  33. 33. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE FOR ASSET OPTIMIZATION. • Recent advances in the industrial automation require a new approach to get plants reducing their start up times and adapting to the varying ore types. Integration of many subsystems is a requirement for improved operational management in metallurgical complexes operations. • The major benefits are increased overall process equipment effectiveness, reduction of organic losses and improved energy and quality management
  34. 34. WHAT ARE THE OPPORTUNITIES? • Increasing competition in the global market place has forced companies to seek new ways to achieve cost-effective production. • Preventive maintenance combined with reliability analysis provides large opportunities for simultaneous cost reduction and productivity improvements • The relationship between losses and equipment effectiveness parallels production quality and equipment availability. • better process and equipment training, • providing information to help develop better next generation equipment.
  35. 35. WHAT ARE THE SOURCES OF DATA? • Maintenance Management Systems • Cost Systems • Predictive Systems • Production Systems • Manufacturer specifications and reliability data
  36. 36. WHAT IS NEEDED? • Environment that simplifies integration of the data with tools available to understand and analyze it.
  37. 37. WHAT IS ASSET OPTIMISATION? • Asset optimization seeks improved operating practices • through the use of process analysis and diagnostic monitoring to notify operations • and maintenance systems of quality deviations • and to permit further improvements. • Asset optimization involves • the manipulation of real time process • and equipment status • to improve performance, • equipment availability • and overall process effectiveness.
  38. 38. WHAT ARE THE DRAWBACKS? • traditional management of the collected information • and the limits of the typical plant organization. • Usually, independent functions • and islands of automation have precluded their implementation.
  39. 39. CLOSING THE LOOP…. • Advances in technology enables a simplified environment to close the loop. • The closing of the loop is at the industry desktop within an analysis framework. • This graphical, adaptable user environment promotes • continuous improvement, • provides tools and facilities to help the user analyze and make discoveries • about the plant and business processes, • and most importantly, helps the user to implement the findings. • In a nutshell, it promotes both continuous improvement and innovation .
  40. 40. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE FOR ASSET OPTIMIZATION. Real Time Information Management Infrastructure Figure 3 shows an overview of the real-time information management infrastructure..
  41. 41. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE FOR ASSET OPTIMIZATION. • A strategic decision involves the identified set of needs in addition to the framework to allow the system evolution, as new technologies arise, for the support of business and operational needs. • The increasing availability of “Web-Services’’ (and the increasing availability of communication bandwidth) will completely change the type and scope of applications, allowing reuse between sites, support from third parties, even those that are remotely located
  42. 42. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE FOR ASSET OPTIMIZATION. shows an example of a pump created from a template.
  43. 43. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE FOR ASSET OPTIMIZATION. • The pump template has the definitions of the attributes of the pump, like suction pressure, the logic for data access and calculation methods for items like efficiency. • This ensures that every pump created from this template has the exact same attributes and calculation methods. Any changes to the template get propagated to all the existing pumps.
  44. 44. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE FOR ASSET OPTIMIZATION. • Figure 4 Notification information management infrastructure
  45. 45. NOTIFICATION INFORMATION MANAGEMENT INFRASTRUCTURE• One of the biggest challenges to process plant management is the accumulation of accurate information on process operations. This information is necessary for any analysis and decision making within the plant and enterprise. Therefore, there is a requirement for meaningful, accurate and consistent data
  46. 46. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE FOR ASSET OPTIMIZATION. • Metallurgical Balance on Grinding and Flotation Plant
  47. 47. METALLURGICAL BALANCE • Material balances calculated from data measured at various locations around process units, inventories, stockpiles, silos, bins, and assays are useful for many purposes, such as yield accounting, on-line control, and process optimization (catalyst selections, reagent schemes, liner replacements, water management, utilities management). To achieve material balances, gross errors or anomalies in the production- data must first be classified, detected, and the source of the data examined. • The Sigmafine plug-in can be used to reconcile the data from inventories, flows, and compositions by performing a mass balance. Figure 7 shows the results in a Web environment for access by management, personnel and external resources. PI Web Parts can then be used for allowing of viewing of the information in the Web.
  48. 48. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE FOR ASSET OPTIMIZATION. • Web Browser showing real time performance indicators
  49. 49. REAL TIME PERFORMANCE INDICATORS • This intergrated approach enables collaboration between operations, engineering, accounting and management to drive the organization’s bottom line according to their business strategy. At the same time personnel can look for opportunities using alternative processing strategies (grinding efficiency, reagents, and blasting methods) to adapt to the changes in ore type to produce the least cost concentrates
  50. 50. REAL TIME INFORMATION MANAGEMENT INFRASTRUCTURE • There is a critical need to integrate legacy systems into real time information management infrastructures. This environment should enable users to transform process data into actionable information. A methodology based on adding the process structure (plant topology) and knowledge of the measurement system and its strategic locations will minimize the global error based on satisfying the material balance constraints.
  52. 52. RISK MANAGEMENT PAGE 70 • Risk management includes the process concerned with identifying, analyzing and responding to appropriate risks. This includes the maximizing of results of positive events and minimizing the consequences of adverse events. • Risk identification: determining which risks are likely to effect the process and documenting the characteristic of each. • Risk quantification: evaluating risk and risk characteristics to asses the range of possible outcomes. • Risk response development: defining enhancement steps for opportunity and response to threats. • Risk Response control: Responding to changes in risk over the course of time.
  53. 53. RISK IDENTIFICATION • Inputs • Product description • Other planning outputs • Historical information • Tools and techniques • Check lists • Flowcharting • Interviewing • Outputs • Sources of risk • Potential risk events • Risk symptoms • Inputs to other processes
  54. 54. RISK QUANTIFICATION • Inputs • Stakeholder risk tolerances • Sources of risk • Potential risk events • Cost Estimates • Activity duration estimates • Tools and techniques • Expected monetary values • Statistical sums • Simulations • Decision trees • Expert judgment • Outputs • Opportunities to pursue • Threats to responds to • Opportunities to ignore • Threats to accept
  55. 55. RISK RESPONSE DEVELOPMENT • Inputs • Opportunities to pursue and threats to respond to • Opportunities to ignore and threats to accept • Tools and techniques • Procurements • Contingency planning • Alternate strategies • Insurance • Outputs • Risk management plan • Inputs to other processes • Contingency plans • Reserves • Contractual agreements
  56. 56. RISK RESPONSE CONTROL • Inputs • Risk management plan • Actual risk events • Additional risk identification • Tools and techniques • Workarounds • Additional risk response development • Outputs • Corrective action • Updates to risk management plan
  57. 57. RISK MINIMIZATION IN PROJECT EVALUATION • The definition and minimization of risk in evaluation of any project is an important consideration. • This is especially true in difficult economic climates where only a small number of potential projects may be evaluated due to capital constraints. • It is therefore important to quickly identify the viability of proceeding with projects at an early stage to ensure the most efficient use of capital reserves. • In these situations an efficient process for project evaluation and risk minimization means that additional projects can be valuated under the same capital budget, increasing the probability of positive financial return for the investors.
  59. 59. STEPS THAT WERE FOLLOWED… • Early contact and collaboration with the tenement holders, who were themselves developing a hard-rock project at the site, was initiated. • Before proceeding it was important to establish the basis for implementation of development outcomes with the existing tenement holder and sign confidentiality agreements to protect both parties. • A core team was put together including a mineralogist, metallurgist and financial analyst. • Historical feasibility and process reports were provided by the tenement holder and the review process was undertaken. • The initial focus of due diligence evaluation was on definition of the potential project size and value.
  60. 60. STEPS THAT WERE FOLLOWED… • This was supported by assessment of where more in-depth data was required, as a measure for development of the subsequent testwork programme.. • The outcomes of initial analysis identified sufficient reserve and value to proceed with the evaluation and undertaken a site visit to establish site layout and existing amenities
  61. 61. THE PROCESS FOR DEVELOPING A TARGETED AND EFFICIENT TESTWORK PROGRAMME• Was based around key parameters to define the most appropriate focus of analysis. • This was achieved using the testwork slider process presented in figure 2. • Using the process. Key variables were analyzed and combined to establish the outcomes required from the testwork programme and consequently the form that the programme should take. • This provided a structured approach to testwork development that could reduce the risk associated with undertaking testwork that was not directly relevant to the final decision- making process
  63. 63. . THE EVALUATION PROCESS… • addressed four key areas in the evaluation of new projects • and assigned them a value in a sliding scale based upon the amount of data already existing. • This has been presented in figure 2 and provided a benchmark for which areas need to be targeted to ensure that sufficiently robust data was available for the decision process in pursuing a project.
  64. 64. THE OUTCOMES OF ANALYSIS • From this simple visual analysis it was clearly identified that although a reasonable amount of quality data was available for metallurgical analysis on robust samples, there was a gap in any mineralogical investigation. For a complex material, such as calcine tailings, an understanding of the mineralogy and key mineral deportment can have a significant impact on the most appropriate processing route to maximize recovery
  65. 65. THE KEY FINDINGS • The analysis's showed that the testwork program was warranted and should focus on measurement of mineralogy. • This could be used in associated with some specific metallurgical testwork targeted at preliminary investigation of the innovative ways to win gold value from this material.
  66. 66. THE IMPLEMENTATION • of the mineralogically focused testwork programme gave sufficiently robust data for the scoping study to be commissioned, examining the viability of a number of innovative process flowsheets. • The scoping study was designed to provide cost estimates to plus minus 30% accuracy and give a basis for preliminary economic analysis. • This would allow an informed decision to be made on whether to proceed to full feasibility analysis or terminate the project before significant outlay had been taken.
  67. 67. Economic Modeling • Base case input data is typically formulated into a table for input into the developed spreadsheet model. • A mass-balance simulation is constructed for each of the process options under consideration. • Capital and operating cost estimates are developed for each option, based on available site or region-specific data. • Comparative analysis is now used, inclusive of specific scenario testing (e.g., varying capital amortization periods, upset conditions). • Cashflow modeling over life of mine is used to determine potential issues using the selected minimum risk option.
  68. 68. RESULTS • concluded that while an acceptable gross margin could be realized over the anticipated three-year project life, • the risk profile was unacceptable in the following aspects: • Gold recovery variability • Relatively low unit recoveries using conventional technologies. • Poor cashflow in the first half of project life • Earnings split precluded a satisfactory earnings scenario for both tenement holder and process operator
  69. 69. Bringing It Together • To make an informed decision on the viability of a project under evaluation the review team should draw on as much technical and economical information as possible. • The process described allows the operator to systematically evaluate important parameters for the project related to overall risk minimization • The project showed sufficient up-side to warrant progressing through to the scoping study and economic analysis stage The outcomes of the deeper analysis showed that return on investment (ROI) was borderline for the project when all capital and operating costs were evaluated. • Using the evaluation philosophy proposed this defined that expenditure should be halted on the project.
  70. 70. CONCLUSION • It can be seen from the procedures implemented that a structured approach to new project evaluation can allow small mining companies to get the best use of limited funds available • By using a disciplined approach decisions can be made quickly and justified to investors with supporting information.
  72. 72. PROCESS STRATEGY DEVELOPMENT PAGE 79 • An effective operations management effort must have • a mission • so it knows where it is going • and a strategy • so that it knows how to get there.
  73. 73. MISSION STATEMENTS • Product design – To lead in research and engineering competencies in all areas of our primary business, designing and producing products and services with outstanding quality and inherent customer value, • Quality management – To attain the execption value that is consisten with our company mission and marketing objectives by close attention to design, procurement, production, and field service opportunities, • Process design – To determine and design or produce the production process and equipment that will be compatible with low cost product, high quality, and a good qulity of work life at economical cost. • Layout design – To achieve through skill, imagination, and resourcefulness in layout and work methods, production and effectiveness and efficiency whilst supporting a high quality of work life
  74. 74. STRATEGY • Strategy is an organizations action plan to achieve the mission • The strategy making / strategy implementing process consist of five Interrelated managerial tasks: • Forming a strategic vision of where the organization is heading • Setting objectives • Crafting a strategy to achieve the desired outcome, • Research – Bench marking with other organizations • Implementing and executing the chosen strategy efficiently and effectively • Evaluating performance and initiating corrective adjustments
  75. 75. FORMING A STRATEGIC VISION • Provide long term direction, • What kind of enterprise the company is trying to become, • Infuse the organization with a sense of purposeful action. • Look beyond today • Think strategically about the impact of new technology on the horizon • How clients needs and expectations are changing • What will it take to overrun the competitors, • Which promising market opportunities ought to be aggressively pursued, • All other internal factors that the company needs to be doing to prepare for the future.
  76. 76. SETTING OBJECTIVES • Converting the strategic vision into specific performance outcomes for the company to achieve • The purpose of setting objectives is to convert managerial strategic vision and business mission into specific • performance targets • results and outcomes • the organization wants to achieve • Setting objectives that require real organizational stretch help: • Build a firewall against complacent coasting • Low grade improvements in organizational performance
  77. 77. CRAFTING A STRATEGY • Companies strategy consists of : • How to grow the business • How to satisfy customers • How to outcompete rivals • How to respond to changing market conditions • How to manage each functional piece of the business and develop organizational capabilities • How to achieve strategic and financial objectives • Competing on differentiation • Competing on cost • Competing on response – reliability and time
  78. 78. OPERATION MANAGEMENT DECISIONS • Goods and service design – much of transformation process. Cost quality and human resource decisions interact strongly with design decisions. Design usually determine the lower limit of cost and the upper limits of quality. • Quality – The customers quality expectations must be determined and policies and procedures established to identify and achieve that quality, • Process and capacity design – Process options are available for products and services. Process decisions commit management to specific technology, quality, human resource use, and maintenance. These expenses and capital commitments will determine much of the firms basic cost structure, • Maintenance – decisions must be made regarding desired levels of reliability and stability, and systems must be established to maintain that reliability and stability.
  79. 79. RESEARCH • Bench marking with other organizations • Product quality • Capacity utilization • Operating efficiency • Investment intensity • Direct cost per unit • Preconditions • Strength and weakness of competitors, • Possible new entrants into the market place, • Substitute products, • Commitment of supplier and distributor, • Current and prospective environmental, legal, technological and economic issues, • Product life cycle which may dictate the limitation of operations strategy, • Resources available within the firm and within the operational management environment, • Integration of operation management strategy with the company’s strategy and other functional areas.
  80. 80. IMPLEMENTING AND EXECUTION • Evaluate internal strengths and weaknesses • Analyze opportunities and threats present in the environment • Identify critical success factors • Build and staff the Organization • Integrate Operations Management with other operations
  81. 81. EVALUATING PERFORMANCE • Evaluating performance and initiating corrective adjustments: • in vision, • long term direction, • objectives, • strategy • execution in light of actual experience • changing conditions • new ideas, • new opportunities.
  83. 83. EQUIPMENT RETROFIT AND RATIONALIZATION PAGE 82 • Two approaches are available • The System approach • The Analytical approach
  84. 84. THE SYSTEM APPROACH • To study a phenomenon or to solve a problem the following steps are used: • Identify a containing whole of which the thing to be studied is a part: • Explain the behavior and the properties of the containing whole; • Explain the behavior and properties to be studied in terms of its function and role in the context of the containing whole. • Potential problems: Hierarchical expansion.
  85. 85. THE ANALYTICAL APPROACH • To study a phenomena or to solve a problem the following steps are used: • Break up the problem into several parts; • Investigate the behavior and properties of the parts taken separately; • Combine the understanding of the various parts into an understanding of the whole. • Assumptions: • The properties of one part are independent from the properties of all the other parts; • The behavior of the whole is a simple combination of the behavior of the parts; • Environment-free; • Potential problems: Reductionism.
  86. 86. SYSTEM VS ANYLITICAL • Analytical Approach • Focus inward on internal structure and detail • Explain any layer in terms of its next lower layer • Descriptive – what does look like • Provides knowledge about structure • Reductionism • Systems Approach • Focus outward on the environment – context • Explain any layer in terms of its next higher layer • Explanatory – why does it do what it does • Provides insight into functionality • Expansionism
  87. 87. THE APPLICATION OF THE SYSTEMS APPROACH MEANS: • Shift the design focus away from concentrating exclusively on mission to concentrating on life cycle, • At the same time the design focus will shift away from concentrating on prime (mission performing) equipment to concentrating on entire system.
  88. 88. NEED IDENTIFICATION AND REQUIREMENTS DETERMINATION PHASE: • Separate the problem from the solution; • Distinguish between the required operational capability and that system which best provides the capability; • It states the required: The quality of a system can never exceed the quality of its required statement • Viz Capability vs system • Operational capability: Transport 100 tons of cargo per 24 hour over 1500 km. • Alternative system concepts: Roads, canal, aircraft, pipeline, railways.
  89. 89. SYSTEM ACQUISITION PHASE: • System acquisition transforms a requirement for an operational capability into a commissioned system which best provides the capability. • Acquisition includes deciding which system will be “best”: • Designing, developing, constructing, manufacturing, and commissioning that system, • Recruiting and training its operator and maintenance people; • And creating or expanding an appropriate support infrastructure. • System acquisition is constrained by: • Life cycle cost, • Acquisition schedule, • Functional performance, • Logistic supportability
  90. 90. SYSTEM ACQUISITION PHASE: • Successful acquisition simultaneously satisfies all four constraints. • Separate system acquisition from technology acquisition, specifically know-how creation and technology development to minimize uncertainties.
  91. 91. OPERATION AND SUPPORT PHASE • Operation means using the system for the operational capability it provides. • The system may sporadically execute missions throughout its useful life. • Support includes activities such as: • corrective and preventative maintenance • modifications, • Modernization. • The operation and design phase imposes both requirements and constraints on the design of the system.
  92. 92. DISPOSAL AND RESTORATION PHASE • The disposal and restoration phase imposes both requirements and constraints on the design of the system
  93. 93. PRINCIPLES OF THE ACQUISITION PROCESS • The acquisition process is a sequence of specified decisions, events and phases of activities directed towards the achievement of project objectives. • Acquisition starts with approving required operational capability and ends with commissioning the system or stopping the project. • Operational application of the system is excluded. • Success depends primarily on: • Competent people, • Rational priorities, • Clearly defined responsibilities. • Appoint a project manager to act as a single point of integrative responsibility.
  94. 94. PRINCIPLES OF THE ACQUISITION PROCESS • Delegate sufficient authority to match the accountability. • Avoid concurrent acquisition • Avoid reactive research and development • Acquisition needs a strong and usable technology base maintained by research and development which is conducted independently of the acquisition of any one specific system. • State requirement for an operational capability in operational terms and not in terms of performance of a system that might provide that capability. • Shift the focus from “What do you want” to “What do you really need? • Reduce technical risks – consider modernizing existing systems • Make use of existing equipment whenever feasible
  95. 95. PRINCIPLES OF THE ACQUISITION PROCESS • Where development is in escapable, its technical objectives shall as far as possible be within the demonstrated state of the art of technology base. • Shift the focus from alternative sources of equipment to alternative concepts for the system • Logistic supportability and life cycle cost are major design objectives equal in importance to acquisition schedule and technical performance. • Start test and evaluation activities as early as possible in as realistic a test environment as feasible. • Stress early hardware testing to improve the quality of decisions • The decision to start production requires a credible estimate of operational suitability and logistic supportability. • As technical uncertainties decrease, increase resource commitments.
  96. 96. ACQUISITION ACTIVITIES • Acquisition consists of four phases • Concept exploration phase • Definition and validation phase • Design and development phase • Construction, manufacture and commissioning phase
  97. 97. Concept exploration phase • Identify and explore all technological feasible operationally practical and economically affordable system concepts. • Include logistic concepts concerning maintenance, support, personnel, training, diagnostics, facilities, etc. • Include operations concepts for personnel, training, basing, command and control, etc. • Explore each concept using appropriate exploratory development models. • Identify the life cycle cost for each concept. • Select the “best “ concepts and document them in a system specification.
  98. 98. DEFINITION AND VALIDATION PHASE: • Identify and specify the constituent elements of the system. • Including support, test and training equipment; • Operating and support personnel; • Procedural data and facilities. • Include all mission performing and support elements. • Document the requirements for each element in its item development specification or equivalent. • Use advanced development models to demonstrate that the required technology is within the state of art of the technology base. • Validate the system concept and system architecture, and allocation of system requirements to elements of the system
  99. 99. Design and development phase • Design, develop, test and evaluate, and qualify the individual elements of the system. • Develop item product specification making use of development models. • Identify or develop specifications for non standard processes and materials which are critical to the correct manufacture of the item. • Conduct initial operational test and evaluation. • Design and qualify the production process, including its logistics, scheduling and quality control. • Use preproduction models to develop work instructions, engineering drawings and associated lists to be used on the plant floor. • Finalize the system support plan, including logist support. • Conduct initial training for operators and maintainers.
  100. 100. CONSTRUCTION, MANUFACTURE AND COMMISSIONING PHASE: • Construct or manufacture, integrate and assemble the elements of the system in the required production quantities. • Include sufficient spares and repairs for initial provision. • Geographically and organizationally deploy the system. • Deployment includes: • facility and support preparation; • transportation of equipment to site; • its installation, integration, calibration and check out; • training of personnel • After formal acceptance tests, hand over each system to the user for operational use.
  101. 101. CONSTRUCTION, MANUFACTURE AND COMMISSIONING PHASE: • The manufacturer may provide interim logistic support. • Transfer overall fleet life cycle management responsibility to the system manager. Determine actual consumption rates for spares and repair parts for replenishment provisioning.
  102. 102. ACQUISITION MILESTONES • Authenticate the required operational capability. Authorise the initiation of an acquisition project • Authenticate the selection of system concepts as specified in the system spectification. Authorize the Definition and validation of the selected system alternative. • Authenticate the selected system via the item development specifications of its elements. Authorise the start of design and development, including industrialization. • Authenticate the system via the item product specification of its elements. Authorise the construction manufacture and commissioning phase.
  103. 103. TAILORING THE ACQUISITION PROCESS: • There is no one single inflexible process applicable to all projects. • The acquisition process merely reflects a typical life cycle of activities. • The acquisition process is primarily aimed at major systems, but the philosophy and approach may be applied to all projects.
  104. 104. ASSESSMENT OF TECHNOLOGICAL UNCERTAINTIES: • The assessment of a system’s technology uncertainty requires an evaluation of two separate aspects: • . • Determine the level of knowhow of each element of the system, and then assess the interdependence between them
  105. 105. REQUIRED OPERATIONAL CAPABILITY • A Required operational capability (ROC) is the main output of the requirement formulation phase and forms the core of the requirements baseline. Requirements formulation includes: • Strategic planning, • Threat assessment, • Market and technology forecasting, etc. • The required operational capability states the desired capability in operational terms. It is not a specification of a system that provides that capability.
  106. 106. A REQUIRED OPERATIONAL CAPABILITY USUALLY ORIGINATES AS FOLLOWS: • A current or projected deficiency in operational capability has arisen, for instance from an escalation in a competitive threat. • An opportunity to enhance the existing capability using new technologies has emerged. • An opportunity to reduce the operating and support costs of an existing capability using technological innovation has arisen. • Also describes the mission to be performed. • The required operational capability should describe mission requirements in terms of applicable business processes. • Define typical mission profiles for both primary and secondary missions.
  107. 107. A REQUIRED OPERATIONAL CAPABILITY USUALLY ORIGINATES AS FOLLOWS: • The environment in which the capability is to operate • A system can only be defined in terms of its environment, which should be described. • The support policy describes the intended method for sustaining an item throughout its life. • The support policy define a support level structure for instance, organizational, intermediate and depot support.
  108. 108. IDENTIFY POLICIES FOR EACH SUPPORT LEVEL, INCLUDING THE FOLLOWING ISSUES: • Diagnostics; • Maintenance and repair; • Support personnel policy, for instance number, skills and knowhow; • Training and training equipment; • Technical data; • Support and test equipment policy; • Provisioning for spares, repair parts and supplies; • Facility policy; • Packaging, handling, storage and transportation;configurati on management.
  109. 109. POLICIES • The support policy describes how the user would like to support the system, and usually reflects current practice. • Generate, investigate, model and evaluate, alternative support concepts. • Select and recommend the “best support concept – the optimum method of supporting the system throughout its life cycle. • The user must authenticate the support concept, which may deviate from the original support policy. • Security policies are similarly translated into security concepts and eventually into security plans. • Related issues may be handled in the same manner.
  110. 110. SYSTEMS • Define external interfaces to other co-functioning systems, especially where such co-functioning systems constrain the acquisition process, viz. transportation, command and control, etc. • Define the physical environment in which the system is to operate and be supported.
  111. 111. CONSTRAINTS TO THE ACQUISITION PROCESS: • Include pertinent constraints to the acquisition process, for instance: • Budget and cash flow, • Life cycle cost ceiling, • Commissioning date, • Total number of systems required and the rate of commissioning; • Phase out consideration of the existing system. • Insight: Don’t assume that original statement of the problem is necessarily the best, or even the right, one.
  112. 112. Engineering Economics • Engineering economy involves the systematic evaluation of the costs and the benefits of proposed engineering projects – will be proposed capital investment be recovered, plus a return commensurate with a risk? • The basic principles of an economic analysis are: • Clearly define the decision to be made. • Develop alternatives. • Selecting the preferred alternative requires an explicit figure of merit or criterion. • The primary criterion is the best use of limited resources. • Consider the consequences of each alternative. All such consequences will occur in the future. • Use a consistent viewpoint.
  113. 113. THE BASIC PRINCIPLES OF AN ECONOMIC ANALYSIS ARE: • Enumerate the future consequences of each alternative in a common unit of measure. • Money is the only common measure. Money units at different times are incommensurate and should be adjusted by means of discounting. • Explicitly consider the non- monetary benefits and non-monetary costs of each alternative. • Only differences among alternatives are relevant in their comparison. • Make uncertainty explicit. • Revisit the decision to thus improve the decision- making process.
  114. 114. THE THREE CLASSIC PROBLEMS OF ENGINEERING ECONOMY ARE: • Which one of a set of mutually-exclusive alternatives is preferable? • Capital budgeting Which set of independent projects should be included in a budget, given a capital constraint? • Replacement analysis Should an existing capital asset be replaced now, or should it be retained for another year?
  116. 116. PRINCIPLES AND PRACTICE OF AUTOMATED CONTROL SYSTEMS PAGE 93 • Process Control • In general terms, control is concerned with the manipulation of inputs to a system (a machine, process, or plant) so that the outputs meet certain specifications. Control is a broad concept comprising long term operating strategy based on: • Process evaluation, • Manual control, • Various forms of real time automatic control, • Such as logic or sequence controlling, • Single variable or multi variable continuous controlling, • Supervisory control.
  117. 117. THE SCIENCE OF PROCESS CONTROL INCLUDES: • The theories of dynamic modeling, • Feedback stability, • Disturbance rejection, • Interaction and controller design. • Technology of process measurement, • Monitoring, • As well as aspects such as interface between • The process • Operator • Control system • Centralized • Distributed system architectures
  118. 118. THE KEY ASPECTS THAT NEED TO BE CONSIDERED WHEN INTRODUCING PROCESS CONTROL IN ORE TREATMENT PLANTS ARE: • What are the key process variables that should be controlled? • Is there an economic justification for control? • What can be controlled? • What can be measured? • What suitable actuators are available? • What configuration of control loops should connect the sensors and actuators and will be possible to obtain satisfactory dynamic performance? • What control philosophy should be used? • Will the reliability of the proposed system be high enough?
  119. 119. PRINCIPLES OF CONTINUOUS CONTROL • Understand and formulate clear control objectives. A good understanding of long- term process operating strategy • considering the following factors • The most important factor is that ore that is brought to the surface must be treated in plant as quickly as possible in order to minimize the ore inventory held on surface. • Reason • mining operation represents +/- 90% of both capital investment and operating cost, and any untreated ore inventory is thus an extremely costly investment • Accommodation should be made for fluctuating feed throughput rate • Plant data must be timorously obtained for management decision making
  120. 120. OPERATING STRATEGY • Maximise throughput of milling • Improved recovery of valuable minerals • Reduction in operating cost
  121. 121. CONTROL OBJECTIVES • Clearly state control objective in relation to plant objective • Eg • in a grinding circuit, possible objectives would be to mainly the finest possible product size at constant throughput, to maximize throughput and keep product size within a limited range or to maximize downstream plant performance • The primary control objective • in any overall process control scheme is therefore that certain key physical variables (e.g. flows, concentrations, densities, levels, temperatures, pressures and speeds) are kept as close as possible to their target values, called set- points, for as much of the time as possible.
  122. 122. CLASSIFICATION OF PROCESS VARIABLES • Outputs: These are the key process variables to be kept as close as possible to their set- points, that is, controlled. The outputs can be further sub-classified as measured outputs and unmeasured outputs. • Inputs: These are the variables that, when changed, cause one or more outputs to change. The inputs can be further sub-classified as control inputs and disturbance inputs.
  123. 123. CONTROL SYSTEM STRUCTURING • Two main approaches are used to guide the structuring of an overall process control system. These are known as the bottom-up approach and the top-down approach. • The bottom-up approach is used most often in practice. It begins with the choice of individual output variables to be measured and controlled and the choice of control inputs. Simple, standard control configurations are then used as building blocks.
  124. 124. THE PRINCIPLE OF FEEDBACK CONTROL • first measuring its effect on a process output and then calculating the necessary correcting input
  125. 125. BALL MILL GRINDING CIRCUIT CONTROL SCHEME BASED ON MAINTAINING COSTANT FEED DENSITY • , typical control principles could be cyclone inlet solids flow control, cyclone underflow density control or mill power maximum- seeking control
  126. 126. THE PRINCIPLE OF FEED FORWARD CONTROL • feedforward control measures the disturbances before they enter the process and calculates the required value of the manipulated variable to maintain the controlled variable at its desired value or set point. If the calculation is done correctly, the controlled variable should remain undisturbed
  127. 127. RATIO CONTROL • B = RA • The output of the multiplier, or the ratio station, FY102B is the required flow of stream Band, therefore, it is used as the set point to the flow controller of stream B, FIC101. So as the flow of stream A varies, the set point to the flow controller of stream B will vary accordingly to maintain both streams at the required ratio. Notice that if a new ratio between the two streams is required, the new R value must be set in the multiplier
  129. 129. CASCADE CONTROL • the controller that controls the primary controlled variable, TICIOI in this case, is referred to as the master controller, outer controller, or primary controller. The controller that controls the secondary controlled variable is usually referred to as the slave controller, inner controller, or secondary controller. • inner or secondary loop must be faster than the outer or primary loop, • When correctly applied, the cascade scheme makes the overall loop more stable and faster responding. • the innermost loop is first tuned and put into automatic while the other loops are in manual. Then we continue moving out
  130. 130. MULTIVARIABLE PROCESS CONTROL • Distillation Column • The two manipulated variables in this process are the stock flow to the machine and the steam flow to the last set of heated drums. Finally, Figure 8-45e depicts a typical distillation column with the necessary controlled variables: column pressure, distillate composition, accumulator level, base level, and tray temperature. To accomplish this control five manipulated variables are used: cooling water flow to the condenser, distillate flow, reflux flow, bottoms flow, and steam flow to the reboiler.
  131. 131. WHAT IS THE CHALLENGE? • To control your plant so that it runs at peak efficiency • Your plant must run at optimal performance • Product consistency is must • Utility and chemical costs must be kept to a minimum to maintain profitability
  132. 132. THE SOLUTION… • Advanced Process control solution for mining and mineral processing plants. • Remove bottlenecks • Reduce energy and chemical consumtion • Produce higher quality products more consistently • At lower production costs
  133. 133. TO STABILIZE AND IMPROVE CRUSHING OPERATION • Integrated control algorithms can be used to make direct adjustment to the ore feed rate of the level in the crusher • The various transportation times present within the crushing system can also be calculated to maintain a stable feed in the crusher
  134. 134. SECONDARY CRUSHER FEED CONTROL • Maintaining the crusher in a choked feed condition • Benefits • Generation of higher fines content • Stable operation improves down stream operation • Increases crusher capacity • Reduces crusher wear
  135. 135. STABILIZE AND IMPROVE SAG MILL CONTROL • Effective grinding largely depends on the load inside the mill • An overloaded mill does not allow movement between the material and balls • An under loaded mill does not take advantage of autogenous grinding
  136. 136. SAG MILL CONTROL • Maintaining mill load at optimum grinding • Benefits • Automatically account for changes in variations in particle size or ore hardness • Minimize production disturbances • Maintain optimal production by minimizing changes in mill speed • Maximizing production rate whilst maintaining consistent grind
  137. 137. BALL MILL PSD CONTROL • Controlling particle size distribution of ball mill • Benefits • Improves product quality by maintaining PSD and maximizing particle recovery • Stabilizes ball mill operation, which will optimize operating points, and chemical addition rates in flotation process to maximize process efficiency
  138. 138. MODELING AND SIMULATION OF PROCESS CONTROL SYSTEMS • When should we use computer simulation in designing a control system? • we must consider how critical the performance of the control system is for the safe and profitable operation of the process • is how confident we are regarding the performance of the control system • the time and effort required to carry out the simulation • the availability of computing facilities, experienced personnel, and sufficient process data to carry out the simulation
  139. 139. DYNAMIC SIMULATION • There are three major steps in performing the dynamic simulation of a process: • Development of a mathematical model of the process and its control system. • Solution of the model equations. • Analysis of the results.
  140. 140. THE BENEFITS OF DYNAMIC SIMULATION FOR THE MINERALS INDUSTRY. PAGE 133 • The primary focus of using dynamic simulations in the mineral industry seems to be thus far on the design process control loops and alternate circuits to improve product quality and/or reduce power consumption
  141. 141. APPLICATIONS • equipment sizing (tanks, pumps, pipes, & valves) • designing advanced process control strategies • check-out of Distributed Control System (DCS) and Programmable Logic Controller (PLC) programs • hazard and operability (HAZOP) analysis • designing and testing start- up and shut-down procedures • operating training • de-bottlenecking of operations after the start- up • energy use optimization
  143. 143. DYNAMIC MODEL OF GRINDING CIRCUIT • the control of d50 of the feed to flotation (the product of the grinding circuit) directly involves at least three(3) control loops; the sump level control via the VSD pump, the slurry density control via controlling the dilution water to the sump, and finally, the cascade control of the hydrcyclone separation via adjusting the feed density. • The control scheme is further complicated by an independent logic to control the pressure drop in the battery of hydrocyclones, where the number of active cyclones is increased or decreased to maintain the delta P within a predefined range
  144. 144. DYNAMIC MODEL WITH I/O COMMUNICATION OBJECTS FOR DCS / PLC CONNECTIVITY • A real plant control system will have all these local controls, and much more, programmed in its DCS/PLC. The exchange of data between the model and the control system is done using two communication objects: Control input (from DCS to model) and • Control Output (from model to DCS). Figure 9 shows the same model used previously but expanded by the addition of I/O objects can be configured to use the communication protocol that is required by the plant’s DCS/PLC hardware.
  146. 146. DE- BOTTLENECKING/ENERGY USE OPTIMIZATION • The model can be easily decoupled from the OTS and be used as a desk tool for process or control engineers to study potential improvements and troubleshoot any known process shortcomings. • New process configurations and improvements in controls can be quickly evaluated, validated and transferred back to the plant control system. This allows for an ongoing process of plant improvements.
  147. 147. BENEFITS OF USING SIMULATION • Cost-effective evaluation of multiple design or production alternatives, • Equipment right-sizing; capital cost reduction, • Controls design integrated with process design and including interactions between equipment, • Pre start-up verification and optimization of the plant’s control system, • Performing “virtual’’ startups and shut-downs against the models, • The most efficient operator training tool, • Ongoing plant improvements plant improvements can be tested first on the model before going on line
  148. 148. TAKING MINERAL PROCESSING PLANT SIMULATION TO A NEW LEVEL PAGE 144• Within the last few years the mining industry has begun to express a need for simulators which move beyond normal process simulation and into the world of production simulation. Such a need requires tools which allow process flowsheet performance assessment over multiple ore types and economic assessment to determine the value fo future projects.
  149. 149. METHODOLOGY • The starting point for developing the production simulator described here was Metso’s existing flowsheet simulation package MinOOcad. MinOOcad is a dynamic simulator; it includes liberation and multi- component separation capabilities (albeit for a single ore type) and it allows the tracking of operating costs in all pieces of the equipment, so it provides a good stepping off point for further development. • The first modification made to minOOcad to turn it into a production simulator was to add multi-ore capability. • . It has been anticipated here that the mine may possess a large number of ore types (up to 20 included here) making up each blend and that the blends to the plant may be changed frequently (either on a regular or irregular basis) over a period of several years for evaluation purposes. Randomness within a mining location
  150. 150. METHODOLOGY • . The properties of each of the ore types involved in the mine plan are captured in a parameter table which can include ore composition, density, crushability, grindability, liberation indices, floatability, abrasivity,etc. • Different ores and mixtures of ore types experience constraints in different parts of a plant (process or materials handling equipment) which limits overall processing rate for any given feed. A production simulator must recognize these constraints or limits and make adjustments to the processing rate accordingly
  151. 151. CASE STUDY: MINE PLAN EXECUTION • In this example a mine plan is run to determine which part of the plant constitutes the main bottleneck for increased tonnage. • The mine plan was chosen for illustration purposes to contain only 3 ore types – soft, medium and hard. The expert system adjusts plant feedrate to keep feedrate to every object below its high-high limit a value determined in the plant or from equipment manufacturer specifications). This strategy will always run the plant at the high limit of one or more pieces of equipment.
  152. 152. MINE PLAN EXECUTION • At the end of the simulation the limits table will show what percentage of the time each piece of equipment was at or above its limits. Identifying the bottleneck, making a change, identifying the new bottleneck is an iterative process that can be accomplished in Metso ProSim to plan the series of investments that maximizes production and financial returns. • This and subsequent simulations over longer times and involving a wider range of ore blends suggest that the ball mills are in fact the bottleneck to increasing tonnage to this plant.
  153. 153. NPV CALCULATION – PERFORMANCE FROM ADDING NEW EQUIPMENT • NPV can be used to decide on the best liner profile for a SAG mill. DEM simulations of the SAG mill with several alternative profiles can be made to determine throughput and liner life. The design influences not only the liner life but also the throughput and power draw as the liner wears. The NPV can then be calculated from the throughput, power draw and liner life. The best design can then be chosen to display a balance between life and throughput.
  155. 155. Choice of equipment supplier • The choice of which make of machine to be installed depends on such considerations as: • Suitability as regards performance characteristics and dimensions • Competence of design • Reputation of machine and manufacturer • Price • Delivery time • Back-up facilities and service • Standardization within the plant or larger organization
  156. 156. General Arrangement Drawings • Elements of good layout • There are certain basic principles to be observed when striving for good plant layout. These are: • The layout must be clear and logical. Each step of the process should occupy a clearly-evident area, and these areas should follow each other • in the logical sequence of the process. Not only will this make for simpler plant control and maintenance, but it will also enhance the plant's aesthetic appeal, making it a pleasanter working environment.
  157. 157. GENERAL ARRANGEMENT DRAWINGS • Transportation requirements must be minimized, whether horizontal or vertical. This applies to everything that has to be moved to, within, or away, from the plant, including ore, residue, reagents, stores, materials, energy, people, and of course, products • Ease of operation, supervision and maintenance must be maximized. • Safety and well-being of personnel must be maximized. • Security must be maximized. • Adequate provision must be made for plant expansion. • These requirements are frequently conflicting, so that the final layout always represents a compromise among them; the best design is the one that achieves the best compromise
  158. 158. Plant Construction and commissioning • Metallurgical involvement in the construction phase • It is highly desirable that the official who will be in charge of plant operation, and, if possible, his second-in-command, should be involved in the design, construction and commissioning process at as early a stage as possible, preferably as part of the metallurgical component of the Project Team. This will ensure their complete familiarity with the design background and operating philosophy of the plant. • Preparation for commissioning, concurrently with the construction phase, or even earlier if possible, the manager designate will have to devote much of his time to preparing for plant startup, for this will be uniquely his responsibility
  159. 159. COMMISSIONING • Commissioning is best carried out by a specially-assembled commissioning group under the plant manager and comprising metallurgists, engineers with artisan backup to carry out minor alterations and trouble-shooting expeditiously, and experienced operating personnel under a plant foreman. No attempt should be made to start up a new plant with inexperienced personnel
  160. 160. COLD COMMISSIONING • Cold commissioning means running the section without process material in it. For example, in commissioning a mill circuit, the mills, feed belts, etc. would be run empty at normal operating speeds, but the mill water reticulation services would be completely functional • In short, it is the stage in which the plant section is brought to the state where it appears to be capable of handling the process stream reasonably efficiently, safely and continuously, but without actually having handled normal process material.
  161. 161. HOT COMMISSIONING • After all obvious faults which would prevent the safe and reasonably efficient handling of the process stream have been eliminated, 'hot commissioning' can commence. • This is the crucial stage at which the actual process material begins to pass through the plant and at which it becomes evident whether or not the effort of the preceding months and years is to be crowned with success
  162. 162. PRACTICAL COMMISSIONING TIPS • If possible, commissioning should be carried out on waste rock to reduce the value of lockup and loss due to incorrect processing. • Avoid having ore, reagents, etc. in storage for extended periods before plant startup. The properties of these materials can be adversely affected during storage so that eventually startup has to be commenced with material for which the plant was not designed. Also fines can set hard and become extremely difficult to move after extended storage.
  163. 163. PRACTICAL COMMISSIONING TIPS  Only partly fill storage facilities such as stockpiles, bins and tanks before startup. Stockpiles, in particular, segregate badly as they are filled, so that unless draw-off occurs reasonably concurrently with filling a large core of fines can form which can seriously affect plant operation and require a long time to eliminate. • Furthermore, if storage has to be emptied for fault correction, obviously the less material to be handled the better
  164. 164. PRACTICAL COMMISSIONING TIPS • Crushers should be set somewhat coarser than designed to begin with and gradually 'pulled up' to correct setting to avoid choking and damage if they are not able to handle actual operating conditions • Commence commissioning on manual control and gradually introduce automatic control as operation settles down. • Run-of-mine mills should initially be fed dry (i.e. without discharge) at the highest rate at which rock can be got into them. This is in order to build up a pebble load as quickly as possible and to avoid pipeline blockage with coarse discharge.
  165. 165. PRACTICAL COMMISSIONING TIPS • When the power draft reaches a maximum and commences to decline, the feed rate should be reduced to hold the power at maximum and dilution water opened. Steel grinding media should not be added until a satisfactory pebble load, • both as regards quantity and size distribution, has been built up. In particular avoid adding steel if the initial feed is fine, as the steel will simply retard the buildup of a pebble load. It is general experience that large run-of mine mills require as much as six months before they achieve efficient operation
  166. 166. PRACTICAL COMMISSIONING TIPS  Have a range of sizes of cyclone spigots and vortex finders available to enable quick changes for rapid optimization. This applies particularly to spigots, whose size is more critical than that of vortex finders. Startup vortex finders need not be rubberized as they will probably be changed before wearing out. • Thickeners should be filled to overflowing with water before startup otherwise the incremental water lockup before they overflow can exceed the drawdown of the return water tank and the mill water system can run empty
  167. 167. PRACTICAL COMMISSIONING TIPS • Thickeners should not be circulated during startup. Because of the higher settling rate of the coarser particles, circulation can cause the concentration of sand in the settled pulp which in turn can cause rake overload and trip- out. It is better to keep the underflow pumps completely stopped with occasional short spells of running (without circulating) • to avoid underflow system blockage, until underflow water: solids has diminished sufficiently to permit continuous draw-off • Remember to fill tanks and sumps which would normally contain re- circulated solutions required in the process, with a suitable temporary substitute to enable the process to get started. Normally clean water is satisfactory
  168. 168. ACCEPTANCE RUNS • Where the design and/or construction of the plant have been carried out by some organization other than the owners, it is usual to include in the contract some form of 'acceptance run'. • During this, inputs and operating conditions of the plant are held as close as possible to those specified in the Process Design Criteria • and a determination is made as to whether the plant is then able to attain the specified operating and output targets. • . A very important point in drawing up the acceptance clauses is that the acceptance criteria should be capable of being measured and that they be very carefully specified and understood by both parties to the contract.
  169. 169. ACCEPTANCE RUNS • For example, it is useless to specify what the characteristics of a certain process stream shall be, when in practice it is impossible to determine them, at any rate to the necessary degree of accuracy. Also, differences of interpretation can result in conflict situations between the parties, and great efforts should be made to avoid them by careful and thorough statement of the acceptance criteria.
  171. 171. A few general rules… • The most critical single item in process design is understanding the feed material the plant will be treating • What is the mine going to be sending to the mill, and how does each of these feed types react metallurgically? • Terry Mcnulty (Mcnulty 1998), in his original paper on the subject noted as one of the common problems of poor start-ups and plant failures “Pilot-scale testing was incomplete or may have been conducted on non- representative samples’’
  172. 172. A FEW GENERAL RULES… • Planning for the estimation of the start-up parameters for a new project should begin during process development and test-work – and management should be kept aware of this estimate. It should not be left as the last, brief step, before completion of the cash flow study • People generally, will spend a very large amount of time in estimating the project’s capital and operating costs. Once these are entered into the cash flow projection, one will find that someone will have to make an estimate of how long it will take the project to come up to full design capacity and to projected recovery
  173. 173. A FEW GENERAL RULES… • If the process chemistry is novel, be sure you completely understand it. Even if the process chemistry is not novel, be sure you understand all of the reactions that will take place • This rule sounds almost silly. If you are involved in development of a hydrometallurgical process, and don’t even really believe that this could happen. Talk to someone who has been around a bit longer.
  174. 174. A FEW GENERAL RULES… • If the use of some new, or leading edge process, or new type of equipment or anything else new is absolutely essential to the economic viability of the plant being designed, go ahead. If not don’t • The correct place, if you possibly can, is to install and test out new stuff is in an existing plant, not a brand new one • New stuff is not bad stuff – quite the opposite. But plan on spending a big bunch of time and effort getting this sort of equipment of process operating up to design
  175. 175. A FEW GENERAL RULES… • The things that you spend the most time and effort on and the potential problems that you plan for – never happen • if you locate and anticipate potential problems and plan how to deal with them, these almost assuredly won’t be the difficult start-up problems that you have to fight your way through.
  176. 176. A FEW GENERAL RULES… • You can have it fast. • You can have it cheap. • You can have it correct. • Pick any two • If you are asked, as you no doubt have been in the past and will no doubt be in the future, to do something in an unrealistic time frame, or with an insufficient budget, or with insufficient testing, you need to make absolutely sure that the entire project team, including the project VP clearly understands the implications of this rule.
  177. 177. A FEW GENERAL RULES… • Rule 1: The client is always right • Rule 2: If the client is wrong, refer to rule 1. • Talk to operators every chance you get, learn from them. They know a lot more about what works than you. The difference between a good plant and a great plant are the operators. Make sure they have input.
  178. 178. A FEW GENERAL RULES… • Every sample or composite selected for metallurgical test-work should be the product of discussions between the project metallurgist and the geological staff: overall composites chosen to represent smaller zones with potentially differing metallurgical characteristics
  179. 179. PLANT DESIGN – WHAT NOT TO DO • Don’t design and build the mill until you have a mine • The reasons why it happens is underestimated ore reserves, lower ore grades than originally estimated, mining problems or higher capital and/or operating costs than original visualized. The cases of “ near misses’’ are usually associated with lower grade ore than originally estimated and the problem was overcome by higher sales prices coming into effect after the plant was built.
  180. 180. PLANT DESIGN – WHAT NOT TO DO • Don’t Skimp on Test Work • Adequate and reliable metallurgical test work is vital to obtain the results needed to develop the flow sheet and design criteria for any given plant. Such test work will most certainly involve bench scale test work and mineralogical examinations, and if deemed necessary, pilot plant operation in some cases
  181. 181. PLANT DESIGN – WHAT NOT TO DO • Don’t discard the use of “gut feeling • when viewing the results of test work. A good example of this “art of gut feeling” was experienced with grinding tests on Newmont’s Gold Quarry ore. A 700 ton sample ore was sent offsite to test- autogenous and semi- autogenous grinding tests. • The tests were monitored by a Newmont engineer and showed that either autogenous or semi- autogenous grinding could be employed. instead of blindly accepting the results, and by using “gut feeling,”
  182. 182. PLANT DESIGN – WHAT NOT TO DO • it was decided to build the foundations of the mill strong enough to carry the load of a semi-autogenous mill operating with 10% ball load and start the mill up in the autogenous mode,. Within a week it was obvious that the mill could not treat the required tonnage and a ball load was added with instant success.
  183. 183. PLANT DESIGN – WHAT NOT TO DO • Don’t jump to conclusions. • There is a tendency in the industry to jump to conclusions when it comes to the treatment of sulfidic gold ores. • The belief often assumed is that because the sulfide content of the ore is high, the material is refractory. A typical case is that of Sherrgold’s gold deposit in Quebec, Canada (a JV with Newmont) some years ago. This ore was highly sulfidic but was not refractory and was successfully milled for several years with recoveries exceeding 90% for gold.
  184. 184. PLANT DESIGN – WHAT NOT TO DO • Don’t Forget Your Economics 101 Classes • Generally speaking if a base metal flotation plant is to be installed, the plan would be to produce the highest grade concentrate at the highest recovery – right? • No not necessarily. If the company owns a smelter nearby (as was the case with Cerro de Corp. in Peru), it may be better from an economic point of view, to produce lower grade concentrates at higher recovery. If on the other hand, the concentrates are to be sold to distant smelters, it would probably be better to produce high grade concentrates even at lower recovery to offset the cost of transportation
  185. 185. PLANT DESIGN – WHAT NOT TO DO • Don’t Leave Certain Important People Out Off the Design Team • In many cases, the plant design team consists of people of various professional disciplines employed by an outside engineering firm. • Sometimes they are well experienced and sometimes they are not. For example, there are very few people who are experienced today in the “out dated or old fashioned” Merrill Crowe process for gold recovery from cyanide leach solutions and in particular, there appears to be an acute shortage of people who can design grinding circuits and to calculate the horsepower needed to power grinding mills. This can result in over estimation or under estimation of the tonnage which can be treated through the grinding circuit
  186. 186. PLANT DESIGN – WHAT NOT TO DO • Don’t Jam The Equipment Into The Smallest Possible Space • There is a tendency to use the smallest possible footprint when placing the equipment in a new or expanded plant, capital costs involved with site grubbing, concrete flooring, foundations, etc. Such practice however, often makes it very difficult for maintenance when the use of mobile cranes and fork-lifts are needed. This is where the assistance of the maintenance superintendent is needed on the design team
  187. 187. PLANT DESIGN – WHAT NOT TO DO • Don’t Install Faulty Electrical Switchgear or Locate It in Tight Corners or Potential Wet Areas • A good practice carried out by the Anglo group in South Africa, is to place the electrical cables in vertical trays rather than in horizontal trays as installed in most plants throughout the world. This prevents the build-up of dirt and dust and rock on top of the cables which can cause cable covering degradation and possible electrical shorts
  188. 188. PLANT DESIGN – WHAT NOT TO DO • Don’t Place the Equipment on Faulty Foundations or On Weak Ground • This should be very obvious, but it has happened and continues to happen. One can ask, “why is that and why should it happen? The obvious answer is carelessness. Good engineering practices have not been followed in the case of structures and adequate ground geotechnical studies have not been followed in the case of equipment placement.
  189. 189. PLANT DESIGN – WHAT NOT TO DO • Don’t Install Unworkable Chutes below Ore Stockpiles and Fine Ore Bins • At Gold Quarry at the primary crushed ore stockpile the ore froze in the winter time in the chute area forcing the use of front end loaders to move the ore from the stockpile to the conveyor belt feeding the secondary crushers
  190. 190. PLANT DESIGN – WHAT NOT TO DO • Don’t Be Stingy On Installing Duplicate Vital Equipment • At Mount Isa concentrator a spare bank of flotation cells, was installed in both, the lead and zinc flotation sections, and above every bank of cells, were spare impellors, hanging on small cranes ready to be dropped, into the cells when the operating mechanism failed. Likewise, every pump was duplicated and the sumps were divided and fed by flexible rubber pipes so as to allow quick pump changes without loss of production. • Such installations cost more , but are well worth the added capital expense to allow for maximum plant throughput and ease of operation.
  191. 191. PLANT DESIGN – WHAT NOT TO DO • Don’t Install Defective Equipment • Equipment often comes out of the factories which has faulty welding, un- tightened bolts, bolts without nuts, cracks, dents, cuts, misshaped, rusted, seized bearings, etc. it is up to the Purchasing Agent and his assistants to carefully inspect all equipment before receiving it from the manufacturers.
  192. 192. PLANT DESIGN – WHAT NOT TO DO • Don’t Hesitate To Use the Natural Contours of the Land • Informer times, it was common to carefully inspect the site of a new plant so as to capitalize on downhill situations to minimize pumping requirements. It was especially common to allow for gravity feeding of tailing dams.
  193. 193. PLANT DESIGN – WHAT NOT TO DO • Don’t Fail to Install Adequate Safety Guards on Machinery and Motors and Prepare Safety Manuals Along With the Plant Design • Of particular interest is to place guards on drive mechanisms where many a life and limb have been lost in the past. Also of importance is to have a good lock out system to prevent start up of machinery while people are working on it. In the industry, over the years, from experience it is known there has been, many deaths and serious injuries caused by accidental start up of equipment which was not properly locked out.
  194. 194. PLANT DESIGN – WHAT NOT TO DO • Don’t Wait To The Last Minute To Prepare Operator Training Manuals • get the operator-training manuals out as early as possible so the new hires can undergo training immediately when they come on board.
  195. 195. PLANT DESIGN – WHAT NOT TO DO • Don’t Hesitate To Design The Plant To Be A Pleasant Place To Work In • There are places throughout the world where a lack of air conditioning and heating of the offices and control rooms and the plants themselves still exist but if one wants to keep good people on the payroll, such facilities must be first class. Again, this is a point which should be considered carefully by the plant design team.
  196. 196. PLANT DESIGN – WHAT NOT TO DO • Don’t Over Automate The Operations Of The Plant • Automation of the operations of mineral dressing plants has been a very good thing with respect to reducing the number of operators needed, maximizing throughput and recoveries and maximizing operating costs. The principle idea of automation is of course, to supply the operator with the tools to do his job better.
  197. 197. PLANT DESIGN – WHAT NOT TO DO • Don’t Neglect The Environment • Keep in mind that strict rules and regulations are now in place all parts the world to protect the environment. In general, these rules are based on certain guidelines set down several years ago by the International Finance Corporation (IFC) and the World Bank and cover limits on several elements contained in solid, liquid and gaseous discharges from mineral dressing plants.
  198. 198. PLANT DESIGN – WHAT NOT TO DO • Of particular interest are heavy metals such as mercury, arsenic, lead, zinc, copper, iron, etc. and soluble compounds such as sulfates, chlorides, fluorides, etc. all lenders worldwide now insist on the borrowers signing off on the World Bank guidelines. • Keep in mind that the mining industry in general and milling plants in particular have a very negative perception among the public which leads them to believe that mining in general is dirty, dangerous and deceptive.
  199. 199. PLANT DESIGN – WHAT NOT TO DO• Don’t Forget To Install A Full Proof Security System • All mineral dressing plants producing base metals concentrates or precious metals or diamonds or gem minerals or industrial minerals or washed coal located domestically • or overseas, require some level of security to protect the employees from harm and the stealing of products and spare parts or reagents. • It is obvious the plants producing high value products like gold, diamond and silver require the highest level of security especially when located in areas where political terrorists, eco terrorists, gangsters, bandits, and anti mining groups operate.
  200. 200. PLANT DESIGN – WHAT NOT TO DO • Don’t Be Afraid To Check Out What Others Are Doing • Part of the design team’s responsibilities is to plan to use the latest and best available technology in the design of the plant they are working on. The team therefore, should check with other operators and equipment suppliers to get the latest and best for the plant. To do this, the team needs to visit other similar plants and discuss the matter with everyone and his brother.
  201. 201. PLANT DESIGN – WHAT NOT TO DO • Don’t Repeat Mistakes Of The Past • At first blush, this would appear to be a difficult task but it is not really so difficult, if approached correctly. The correct way is the way Newmont handed this matter several years ago when the company set up a small committee. There was a careful review, of all plans and other information associated with new installations or expansions to see that former mistakes had not been repeated. The system worked very well
  202. 202. THE ROLE OF INNOVATION IN PLANT DESIGN • The Business Case For Innovation • In all cases, the divers for innovation are to improve the overall economics of a project by; decreasing capital (possibly at the expense of an increase in operating cost), • decreasing operating cost (possibly at the expense of an increase in capital cost),
  203. 203. THE BUSINESS CASE FOR INNOVATION • improving metal recovery, improving product quality, improving some other attribute of the process (e.g., safety, health or environmental considerations), or combinations of these. By its nature, innovation introduces risk. • Any change or alteration in the way something is done has an element of the unknown which adds risk. In most cases, the risk can be quantified, or at least partially – quantified,
  204. 204. THE ROLE OF INNOVATION IN PLANT DESIGN • The Business Case For Innovation • Risk of increased downtime (lower availability) of equipment and process • Risk of delay in start-up and ramp up of production • Risk throughput rate less than design • Risk of lower metal recovery • Risk of higher installed capital cost or operating cost • Risk of technical failure of equipment or a process step (quantifiable in terms of downtime, start-up delay, loss of production, replacement cost, etc) • Safety, health, and / or environmental risks
  205. 205. THE ROLE OF INNOVATION IN PLANT DESIGN Types of innovation • Process development • Process selection • Flowsheet design • Equipment selection and design • Process commissioning and optimization
  206. 206. THE ROLE OF INNOVATION IN PLANT DESIGN • Key guidelines for the early stage process development and evaluation include the following • Perform extensive and effective benchmarking on similar deposits and projects worldwide • Wherever possible, replicate or duplicate what has been done before, if it fits the new orebody – adopt and adapt with pride • Utilize key experts (internal and external) to review, evaluate, critique and rank options (including innovative aspects and opportunities),
  207. 207. KEY GUIDELINES • Quantify the benefits and risks associated with each option identified make as many decisions on options and alternatives (including innovation) as you can early in the development of the project, • Do not carry an option forward to the process selection step unless you have completed a risk assessment and you know the risk can be managed and how it will be managed.
  208. 208. Managing The Innovation Process • Guidelines to incorporate effective innovation in plant design • Involve key client-side staff early in the process development phase (before flowsheet design, detailed engineering and equipment selection), including the plant or Process Manager, Operations Superintendent, Chief Metallugist, Maintenance Superintendent • Bring an outside expertise to assist with plant design, including brainstorming sessions, flowsheet review, risk rewards review for innovative aspects of design