Steady state simulation is an essential tool for plant design and pre=control optimisation
Mineral processing plant design and optimisation 28 sept 2012
MINERAL PROCESSING PLANT DESIGN and OPTIMISATION MR.BASDEW ROOPLAL METALLURGICAL AND BUSINESS CONSULTANT
Plant Design and Process Evaluation and Commissioning control General Procedure for plant Case Study: Real time design information Plant Design Simulation and Optimization management infrastructure for asset optimization. Risk and Loss Control Management Case Study: The early stage Risk minimization in Process Flowsheet design Process Strategy Development
Equipment retrofit and General Rationalization using the Plant Construction and System Acquisition Commissioning approach , A few general Rules• Principles and Practice of Plant Design - What not Automated control systems to do?• The Benefits of Dynamic • The role of innovation in Simulation for the Minerals Mineral Processing and Industry Metallurgical Plant Design Taking mineral processing plant simulation to a new level – Inclusion of mine plan and financial performance
General Procedure for plant Detailed Design design Metallurgical involvement in Process Design the construction phase Flow sheet Design Commissioning Process Plant Simulation Cold commissioning General Arrangement • Hot commissioning Drawings Practical commissioning tips Acceptance runs Conclusions
Importance of Good Plant Design Delays in and Punctual Commissioning commissioning A good plant design can minimize capital expenditure and maximize can prove to on long term profits. become an A good plant design together with extremely costly careful planning and execution of exercise in terms the startup can greatly contribute towards: of profit loss due easing commissioning problems, to loss of and can ensure the plant brought production into production Timorously To Design capacity and efficiency, And Within budget.
General Procedure for plant Costing and preparation of design definitive budget, Ore testing, Production of final Process definition, flowsheet, Production of basic Construction, flowsheet, Commissioning Production of piping and instrument drawings, Production of general arrangement drawings and conceptual models, Equipment selection and specification
Process design criteria General information A statement of what the regarding the externally plant will be required to do imposed parameters of and the framework in which the design it will have to accomplish it. Normally prepared by the It includes: mining and financial The capacity of the plant, consultants, Material to be treated, Deals essentially with: The sources of feed, What the plant is to The product, achieve, Time schedule for the commissioning of the various stages,
Basic directive to the The design plant designer, Setting limits within metallurgist must which they should insist that he be operate, given the Process And targets they must attain. design criteria as part of the essential documentation of his commissioning
The flowsheet deals with the The design process means by which the Arranging in objectives are to be attained diagrammatic form the Diagrammatic definition of necessary equipment, how the requirements specified in the design installations and criteria are to be achieved. interconnections to Flowsheet design is a major achieve the goals and vital part of process specified in the design design, criteria, The correct choice of Compiling with the flowsheet is crucial to the treatment method technical and financial indicated by the success. laboratory analysis, And any other source of information or requirements
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
For flowsheet to be used in Flow rates must be subsequent costing, based on the full length evaluation, and design of time as specified on stages it must be quantified. the design criteria, Ie. It must include the Initial flow rates must be following information correct when actual running Flow streams times are available throughput of the plant, Secondary data calculations Equipment to be based on mass balance installed, around the equipment must A table showing flow then be shown. and equipment data, All primary data (data on which the flowsheet is based as per design criteria and test results)
Estimation of actual Estimating actual running time running time When the actual running Initially flow data is based time for the various on 100% running time, equipment is estimated Consideration must be the initial flow rates can be corrected using the given to the number of following factors: hours it will be manned Hours in month used and is planned to run, for initial flowrate The proportion of lost calculation / Estimated time due to random actual running time in unplanned breakdowns the same length month and stoppages must also for the type of machine be considered. involved. The legal constraints of operation must also be
The following data Equipment sizing and selection must also be The design procedures so far tabulated obtained described have provided from the lab results some of the essential data on in order to complete which equipment sizing and the flow sheet: selection can be based, Size distribution, namely the flow data pH, pertaining to each stream in temperatures and the plant. Reagent concentrations
The next step is to determine with the help of The decision as to this data, what capacity which is the correct volume or energy input is required to bring about combination is whatever change is essentially an economic required in each stream, one, that is, whether of position, size distribution, chemical determination of the state, moisture content, etc relative profitabilities of the various alternatives. there will be several combinations of available sizes and numbers of the result of the above machine that will fulfil each requirement calculation will usually indicate that, in the case of major equipment , big is beautiful
Combines the following: A flow sheet A phase model A mathematical model A set of algorithms
The following A mathematical elements are model for each unit combined operation Flowsheet A set of algorithms A phase model For data reconcilation Raw material Model calibration Reagents Unit operation sizing Products Full material balance Water calculation Waste Power consumption Capital cost calculations
Assessing the Plant Use reverse simulation requirements in terms to back calculate the of: dimensions of main Flowsheet pieces of equipment Stream description feed Simulate the future characteristics plant operation and And main performance calculate the Capital objectives investment A preliminary material Compare several flow balance is established sheets in terms of by direct simulation technical performance Which yields an ideal and financial description of all the implications streams
Use material balancing Multiply all streams by techniques to reconcile scale up factor all experimental data Back calculate the coming from sampling dimensions of the main campaign during pilot pieces of equipment in plant test industrial conditions Build a simulation of Simulate the future the pilot plant by plant operations in calibrating each unit various configurations operation model by and calculate the capital using coherent data investment
Use material balance Environmental techniques to reconcile all Tailings stability available operating plant Waste minimization and data Water recycling Build a simulation of the existing process plant by Economic calibrating each unit Estimation of capital cost operation model using investment coherent plant data Reactive consumtion 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
Two kinds of Systems for gathering information and analyzing data of processing are a long term nature for important for the statistical and effective control of accounting purposes metallurgical Plants Short term data required for the control of the plant. This information is analyses and action taken immediatedly.
The requirements for • For process evaluation the primary requirement is these are different 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.
Components of • Sampling to obtain representative data Process Evaluation • Sample preparation, • measurement of mass flowrate • analysis of sample • analysis of data to calculate metallurgical balance.
Recent advances in the The major benefits are industrial automation increased overall require a new approach process equipment to get plants reducing effectiveness, reduction their start up times and of organic losses and adapting to the varying improved energy and ore types. Integration of quality management many subsystems is a requirement for improved operational management in metallurgical complexes operations.
Increasing competition in the better process and global market place has equipment training, forced companies to seek providing information to new ways to achieve cost- help develop better next effective production. generation equipment. 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.
Maintenance Management Systems Cost Systems Predictive Systems Production Systems Manufacturer specifications and reliability data
Environment that simplifies integration of the data with tools available to understand and analyze it.
Asset optimization Asset optimization seeks improved involves operating practices the manipulation of real through the use of time process process analysis and equipment status and diagnostic to improve monitoring to notify performance, operations equipment availability and maintenance systems of quality and overall process deviations effectiveness. and to permit further improvements.
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.
Advances in technology This graphical, adaptable enables a simplified user environment promotes environment to close the continuous improvement, loop. provides tools and facilities The closing of the loop is at to help the user analyze the industry desktop within and make discoveries an analysis framework. 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 .
Real Time Information Management InfrastructureFigure 3 shows an overview of the real-time information managementinfrastructure..
A strategic decision The increasing involves the availability of “Web- identified set of Services’’ (and the increasing availability needs in addition to of communication the framework to bandwidth) will allow the system completely change the evolution, as new type and scope of technologies arise, applications, allowing for the support of reuse between sites, support from third business and parties, even those that operational needs. are remotely located
shows an example of a pump created from a template.
The pump template This ensures that every has the definitions of pump created from this template has the exact the attributes of the same attributes and pump, like suction calculation methods. pressure, the logic Any changes to the for data access and template get calculation methods propagated to all the for items like existing pumps. efficiency.
Figure 4 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
Metallurgical Balance on Grinding and Flotation Plant
Material balances calculated The Sigmafine plug-in can be from data measured at used to reconcile the data various locations around from inventories, flows, and process units, inventories, compositions by performing stockpiles, silos, bins, and a mass balance. Figure 7 assays are useful for many shows the results in a Web purposes, such as yield environment for access by accounting, on-line control, management, personnel and and process optimization external resources. PI Web (catalyst selections, reagent Parts can then be used for schemes, liner replacements, allowing of viewing of the water management, utilities information in the Web. 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.
Web Browser showing 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
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.
Risk management Risk quantification: includes the process evaluating risk and risk concerned with characteristics to asses the identifying, analyzing and range of possible responding to appropriate outcomes. risks. This includes the Risk response maximizing of results of development: defining positive events and enhancement steps for minimizing the opportunity and response consequences of adverse to threats. events. Risk Response control: Risk identification: Responding to changes in determining which risks risk over the course of are likely to effect the time. process and documenting the characteristic of each.
Inputs Outputs Product description Sources of risk Other planning Potential risk events outputs Risk symptoms Historical Inputs to other information processes Tools and techniques Check lists Flowcharting Interviewing
Inputs Outputs Stakeholder risk Opportunities to pursue tolerances Threats to responds to Sources of risk Opportunities to ignore Potential risk events Threats to accept Cost Estimates Activity duration estimates Tools and techniques Expected monetary values Statistical sums Simulations Decision trees Expert judgment
Inputs Outputs Opportunities to Risk management plan pursue and threats to Inputs to other respond to processes Opportunities to ignore Contingency plans and threats to accept Reserves Tools and techniques Contractual agreements Procurements Contingency planning Alternate strategies Insurance
Inputs Outputs Risk management Corrective action plan Updates to risk Actual risk events management plan Additional risk identification Tools and techniques Workarounds Additional risk response development
The definition and It is therefore important to minimization of risk in quickly identify the viability evaluation of any project is of proceeding with projects an important consideration. at an early stage to ensure This is especially true in the most efficient use of difficult economic climates capital reserves. where only a small number In these situations an of potential projects may be efficient process for project evaluated due to capital evaluation and risk constraints. minimization means that additional projects can be valuated under the same capital budget, increasing the probability of positive financial return for the investors.
Early contact and A core team was put collaboration with the together including a tenement holders, who mineralogist, metallurgist were themselves and financial analyst. developing a hard-rock Historical feasibility and project at the site, was process reports were initiated. provided by the tenement Before proceeding it was holder and the review important to establish the process was undertaken. basis for implementation The initial focus of due of development outcomes diligence evaluation was with the existing tenement on definition of the holder and sign potential project size and confidentiality agreements value. to protect both parties.
This was supported The outcomes of by assessment of initial analysis where more in-depth identified sufficient data was required, as reserve and value to a measure for proceed with the development of the evaluation and subsequent testwork undertaken a site visit programme.. to establish site layout and existing amenities
Was based around key This provided a parameters to define the structured approach to most appropriate focus of testwork development analysis. that could reduce the risk This was achieved using associated with the testwork slider process undertaking testwork that presented in figure 2. was not directly relevant Using the process. Key to the final decision- variables were analyzed making process and combined to establish the outcomes required from the testwork programme and consequently the form that the programme should take.
addressed four key This has been areas in the evaluation presented in figure 2 of new projects and provided a and assigned them a benchmark for which value in a sliding scale areas need to be based upon the targeted to ensure that amount of data sufficiently robust already existing. data was available for the decision process in pursuing a project.
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
The analysiss showed This could be used in that the testwork associated with some program was specific metallurgical warranted and should testwork targeted at focus on preliminary measurement of investigation of the mineralogy. innovative ways to win gold value from this material.
of the mineralogically The scoping study was focused testwork designed to provide cost programme gave estimates to plus minus sufficiently robust data for 30% accuracy and give a the scoping study to be basis for preliminary commissioned, examining economic analysis. the viability of a number This would allow an of innovative process informed decision to be flowsheets. made on whether to proceed to full feasibility analysis or terminate the project before significant outlay had been taken.
Base case input data is Comparative analysis is typically formulated into a now used, inclusive of table for input into the specific scenario testing developed spreadsheet (e.g., varying capital model. amortization periods, A mass-balance upset conditions). simulation is constructed Cashflow modeling over for each of the process life of mine is used to options under determine potential issues consideration. using the selected Capital and operating cost minimum risk option. estimates are developed for each option, based on available site or region- specific data.
concluded that while an the risk profile was acceptable gross margin unacceptable in the could be realized over the following aspects: anticipated three-year Gold recovery variability project life, 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
To make an informed decision The outcomes of the deeper on the viability of a project analysis showed that return on under evaluation the review investment (ROI) was team should draw on as much borderline for the project when technical and economical all capital and operating costs information as possible. were evaluated. The process described allows Using the evaluation the operator to systematically philosophy proposed this evaluate important parameters defined that expenditure should for the project related to overall be halted on the project. risk minimization The project showed sufficient up-side to warrant progressing through to the scoping study and economic analysis stage
It can be seen from the By using a disciplined procedures approach decisions implemented that a can be made quickly structured approach and justified to to new project investors with evaluation can allow supporting small mining information. companies to get the best use of limited funds available
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.
Product design – To lead in Process design – To research and engineering determine and design or competencies in all areas of produce the production our primary business, process and equipment that designing and producing will be compatible with low products and services with cost product, high quality, outstanding quality and and a good qulity of work inherent customer value, life at economical cost. Quality management – To Layout design – To achieve attain the execption value through skill, imagination, that is consisten with our and resourcefulness in company mission and layout and work methods, marketing objectives by close production and effectiveness attention to design, and efficiency whilst procurement, production, supporting a high quality of and field service work life opportunities,
Strategy is an Forming a strategic organizations action vision of where the plan to achieve the organization is heading mission Setting objectives The strategy making / Crafting a strategy to strategy implementing achieve the desired process consist of five outcome, Interrelated managerial Research – Bench marking with tasks: other organizations Implementing and executing the chosen strategy efficiently and effectively Evaluating performance and initiating corrective adjustments
Provide long term Look beyond today direction, Think strategically about What kind of enterprise the impact of new the company is trying to technology on the horizon become, How clients needs and Infuse the organization expectations are changing with a sense of purposeful What will it take to action. 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.
Converting the strategic Setting objectives that vision into specific require real performance outcomes organizational stretch for the company to help: achieve Build a firewall against The purpose of setting complacent coasting objectives is to convert Low grade managerial strategic improvements in organizational vision and business performance mission into specific performance targets results and outcomes the organization wants to achieve
Companies strategy Competing on consists of : differentiation How to grow the Competing on cost business Competing on response – How to satisfy customers reliability and time 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
Goods and service design – Process and capacity design – much of transformation Process options are available for process. Cost quality and products and services. Process human resource decisions decisions commit management interact strongly with to specific technology, quality, design decisions. Design human resource use, and usually determine the maintenance. These expenses lower limit of cost and the and capital commitments will upper limits of quality. determine much of the firms Quality – The customers basic cost structure, quality expectations must Maintenance – decisions must be be determined and policies made regarding desired levels of and procedures established reliability and stability, and to identify and achieve that systems must be established to quality, maintain that reliability and stability.
Bench marking with other Current and prospective organizations environmental, legal, Product quality technological and economic Capacity utilization issues, Product life cycle which Operating efficiency may dictate the limitation Investment intensity of operations strategy, Direct cost per unit Resources available within Preconditions the firm and within the Strength and weakness operational management of competitors, environment, Possible new entrants Integration of operation into the market place, management strategy with Substitute products, the company’s strategy and other functional areas. Commitment of supplier and distributor,
Evaluate internal Build and staff the strengths and Organization weaknesses Integrate Operations Analyze Management with opportunities and other operations threats present in the environment Identify critical success factors
Evaluating execution in light of performance and actual experience initiating corrective changing conditions adjustments: new ideas, new opportunities. in vision, long term direction, objectives, strategy
Two approaches are available The System approach The Analytical approach
To study a Explain the behavior phenomenon or to and properties to be solve a problem the studied in terms of its following steps are function and role in used: the context of the containing whole. Identify a containing whole of which the Potential problems: thing to be studied is Hierarchical a part: expansion. Explain the behavior and the properties of the containing whole;
To study a phenomena Assumptions: or to solve a problem The properties of one the following steps are part are independent used: from the properties of Break up the problem all the other parts; into several parts; The behavior of the Investigate the behavior whole is a simple and properties of the combination of the parts taken separately; behavior of the parts; Combine the Environment-free; understanding of the Potential problems: various parts into an Reductionism. understanding of the whole.
Analytical Approach Systems Approach Focus inward on Focus outward on the internal structure and environment – context detail Explain any layer in Explain any layer in terms of its next higher terms of its next lower layer layer Explanatory – why does Descriptive – what does it do what it does look like Provides insight into Provides knowledge functionality about structure Expansionism Reductionism
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.
Separate the problem Viz Capability vs from the solution; system Distinguish between Operational capability: the required Transport 100 tons of cargo per 24 hour over operational capability 1500 km. and that system which best provides Alternative system the capability; concepts: Roads, It states the required: canal, aircraft, The quality of a pipeline, railways. system can never exceed the quality of its required statement
System acquisition And creating or expanding an transforms a requirement appropriate support for an operational infrastructure. capability into a System acquisition is commissioned system constrained by: which best provides the Life cycle cost, capability. Acquisition schedule, Acquisition includes Functional performance, deciding which system Logistic supportability will be “best”: Designing, developing, constructing, manufacturing, and commissioning that system, Recruiting and training its operator and maintenance people;
Successful acquisition simultaneously satisfies all four constraints. Separate system acquisition from technology acquisition, specifically know-how creation and technology development to minimize uncertainties.
Operation means using The operation and design the system for the phase imposes both operational capability it requirements and constraints provides. on the design of the system. The system may sporadically execute missions throughout its useful life. Support includes activities such as: corrective and preventative maintenance modifications, Modernization.
The disposal and restoration phase imposes both requirements and constraints on the design of the system
The acquisition process is Success depends a sequence of specified primarily on: decisions, events and Competent people, phases of activities Rational priorities, directed towards the Clearly defined achievement of project responsibilities. objectives. Appoint a project Acquisition starts with manager to act as a single approving required point of integrative operational capability and responsibility. ends with commissioning the system or stopping the project. Operational application of the system is excluded.
Delegate sufficient authority State requirement for an to match the accountability. operational capability in Avoid concurrent acquisition operational terms and not in Avoid reactive research and terms of performance of a development system that might provide that capability. Acquisition needs a strong Shift the focus from “What and usable technology base do you want” to “What do maintained by research and you really need? development which is conducted independently of Reduce technical risks – the acquisition of any one consider modernizing specific system. existing systems Make use of existing equipment whenever feasible
Where development is in Start test and evaluation escapable, its technical activities as early as possible objectives shall as far as in as realistic a test possible be within the environment as feasible. demonstrated state of the art Stress early hardware testing of technology base. to improve the quality of Shift the focus from decisions alternative sources of The decision to start equipment to alternative production requires a concepts for the system credible estimate of Logistic supportability and operational suitability and life cycle cost are major logistic supportability. design objectives equal in As technical uncertainties importance to acquisition decrease, increase resource schedule and technical commitments. performance.
Acquisition consists of four phases Concept exploration phase Definition and validation phase Design and development phase Construction, manufacture and commissioning phase
Identify and explore all Explore each concept technological feasible using appropriate operationally practical exploratory development and economically models. affordable system Identify the life cycle cost concepts. for each concept. Include logistic concepts Select the “best “ concepts concerning maintenance, and document them in a support, personnel, system specification. training, diagnostics, facilities, etc. Include operations concepts for personnel, training, basing, command and control, etc.
Identify and specify the Document the constituent elements of requirements for each the system. element in its item Including support, test development specification and training equipment; or equivalent. Operating and support Use advanced personnel; development models to Procedural data and demonstrate that the facilities. required technology is within the state of art of Include all mission the technology base. performing and support Validate the system elements. concept and system architecture, and allocation of system requirements to elements of the system
Design, develop, test and Design and qualify the evaluate, and qualify the production process, individual elements of the including its logistics, system. scheduling and quality Develop item product control. specification making use Use preproduction of development models. models to develop work Identify or develop instructions, engineering specifications for non drawings and associated standard processes and lists to be used on the materials which are plant floor. critical to the correct Finalize the system manufacture of the item. support plan, including Conduct initial logist support. operational test and Conduct initial training evaluation. for operators and maintainers.
Construct or Deployment includes: manufacture, integrate facility and support and assemble the preparation; elements of the system transportation of in the required equipment to site; production quantities. its installation, integration, calibration Include sufficient and check out; spares and repairs for training of personnel initial provision. After formal acceptance Geographically and tests, hand over each organizationally deploy system to the user for the system. operational use.
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.
Authenticate the Authenticate the selected required operational system via the item capability. Authorise development specifications of the initiation of an its elements. Authorise the acquisition project start of design and development, including Authenticate the industrialization. selection of system Authenticate the system concepts as specified in the system via the item product spectification. specification of its Authorize the elements. Authorise the Definition and construction validation of the manufacture and selected system commissioning phase. alternative.
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.
The assessment of a Determine the level of system’s technology knowhow of each uncertainty requires element of the system, an evaluation of two and then assess the separate aspects: interdependence . between them
A Required operational The required capability (ROC) is the operational capability main output of the states the desired requirement capability in operational formulation phase and terms. It is not a forms the core of the specification of a system requirements baseline. that provides that Requirements capability. formulation includes: Strategic planning, Threat assessment, Market and technology forecasting, etc.
A current or projected Also describes the mission deficiency in operational to be performed. capability has arisen, for The required operational instance from an capability should describe mission requirements in terms escalation in a competitive of applicable business threat. processes. An opportunity to Define typical mission profiles enhance the existing for both primary and secondary missions. capability using new technologies has emerged. An opportunity to reduce the operating and support costs of an existing capability using technological innovation has arisen.
The environment in • The support policy define which the capability is a support level structure to operate for instance, organizational, A system can only be intermediate and depot defined in terms of its support. environment, which should be described. The support policy describes the intended method for sustaining an item throughout its life.
Diagnostics; Support and test Maintenance and equipment policy; repair; Provisioning for spares, Support personnel repair parts and policy, for instance supplies; number, skills and Facility policy; knowhow; Packaging, handling, Training and training storage and equipment; transportation;configur Technical data; ation management.
The support policy The user must describes how the user authenticate the would like to support support concept, which the system, and usually may deviate from the reflects current practice. original support policy. Generate, investigate, Security policies are model and evaluate, similarly translated into alternative support security concepts and concepts. eventually into security Select and recommend plans. the “best support Related issues may be concept – the optimum handled in the same method of supporting manner. the system throughout its life cycle.
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.
Include pertinent Phase out constraints to the consideration of the acquisition process, existing system. for instance: Insight: Don’t assume Budget and cash flow, that original Life cycle cost ceiling, statement of the Commissioning date, problem is Total number of necessarily the best, systems required and or even the right, one. the rate of commissioning;
Engineering economy The basic principles of an involves the systematic economic analysis are: evaluation of the costs and Clearly define the decision the benefits of proposed to be made. engineering projects – will be Develop alternatives. proposed capital investment be recovered, plus a return Selecting the preferred alternative requires an commensurate with a risk? 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.
Enumerate the future Explicitly consider the consequences of each non-monetary benefits alternative in a and non-monetary costs common unit of of each alternative. measure. Only differences among Money is the only alternatives are relevant common measure. in their comparison. Money units at different Make uncertainty times are explicit. incommensurate and Revisit the decision to should be adjusted by thus improve the means of discounting. decision-making process.
Which one of a set of • Replacement analysis mutually-exclusive Should an existing capital alternatives is asset be replaced now, or preferable? should it be retained for Capital budgeting another year? Which set of independent projects should be included in a budget, given a capital constraint?
Process Control Process evaluation, In general terms, Manual control, control is concerned Various forms of real with the manipulation time automatic control, of inputs to a system (a Such as logic or machine, process, or sequence controlling, plant) so that the outputs meet certain Single variable or multi specifications. Control is variable continuous a broad concept controlling, comprising long term Supervisory control. operating strategy based on:
The theories of As well as aspects dynamic modeling, such as interface Feedback stability, between Disturbance rejection, The process Operator Interaction and controller design. Control system Centralized Technology of process Distributed system measurement, architectures Monitoring,
What are the key What configuration of process variables that control loops should connect the sensors and should be controlled? actuators and will be Is there an economic possible to obtain justification for satisfactory dynamic control? performance? What can be What control controlled? philosophy should be What can be measured? used? What suitable actuators Will the reliability of are available? the proposed system be high enough?
Understand and Reason formulate clear control mining operation objectives. A good represents +/- 90% of understanding of long- both capital investment term process operating and operating cost, and strategy any untreated ore inventory is thus an considering the following extremely costly factors investment The most important factor Accommodation should is that ore that is brought be made for fluctuating to the surface must be feed throughput rate treated in plant as quickly as possible in order to Plant data must be minimize the ore timorously obtained for inventory held on surface. management decision making
Maximise throughput of milling Improved recovery of valuable minerals Reduction in operating cost
Clearly state control The primary control objective in relation to objective plant objective in any overall process control scheme is therefore that certain key Eg physical variables (e.g. in a grinding circuit, flows, concentrations, possible objectives would densities, levels, be to mainly the finest temperatures, pressures possible product size at and speeds) are kept as constant throughput, to close as possible to their maximize throughput and target values, called set- keep product size within a points, for as much of the limited range or to time as possible. maximize downstream plant performance
Outputs: These are the Inputs: These are the key process variables to be kept as close as variables that, when possible to their set- changed, cause one or points, that is, more outputs to controlled. The outputs change. The inputs can be further sub- classified as measured can be further sub- outputs and classified as control unmeasured outputs. inputs and disturbance inputs.
Two main approaches The bottom-up are used to guide the approach is used most structuring of an overall often in practice. It process control system. begins with the choice These are known as the of individual output bottom-up approach variables to be and the top-down measured and approach. controlled and the choice of control inputs. Simple, standard control configurations are then used as building blocks.
first measuring its effect on a process output and then calculating the necessary correcting input
, typical control principles could be cyclone inlet solids flow control, cyclone underflow density control or mill power maximum-seeking 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
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
the controller that controls When correctly applied, the the primary controlled cascade scheme makes the variable, TICIOI in this case, overall loop more stable and is referred to as the master faster responding. controller, outer controller, the innermost loop is first or primary controller. The tuned and put into automatic controller that controls the while the other loops are in secondary controlled manual. Then we continue variable is usually referred to moving out as the slave controller, inner controller, or secondary controller. inner or secondary loop must be faster than the outer or primary loop,
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.
To control your plant Your plant must run so that it runs at peak at optimal efficiency performance Product consistency is must Utility and chemical costs must be kept to a minimum to maintain profitability
Advanced Process Remove bottlenecks control solution for Reduce energy and mining and mineral chemical consumtion processing plants. Produce higher quality products more consistently At lower production costs
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
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
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
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
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
When should we use we must consider how computer simulation in critical the performance of designing a control system? 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
There are three major Development of a steps in performing mathematical model the dynamic of the process and its simulation of a control system. process: Solution of the model equations. Analysis of the results.
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
equipment sizing designing and testing (tanks, pumps, pipes, & start-up and shut-down valves) procedures designing advanced operating training process control de-bottlenecking of strategies operations after the check-out of Distributed start-up Control System (DCS) energy use optimization and Programmable Logic Controller (PLC) programs hazard and operability (HAZOP) analysis
the control of d50 of the The control scheme is feed to flotation (the further complicated by an product of the grinding independent logic to circuit) directly involves at control the pressure drop least three(3) control in the battery of loops; the sump level hydrocyclones, where the control via the VSD pump, number of active cyclones the slurry density control is increased or decreased via controlling the to maintain the delta P dilution water to the within a predefined range sump, and finally, the cascade control of the hydrcyclone separation via adjusting the feed density.
A real plant control Control Output (from system will have all model to DCS). Figure 9 these local controls, and shows the same model much more, used previously but programmed in its expanded by the DCS/PLC. The addition of I/O objects exchange of data can be configured to use between the model and the communication the control system is protocol that is required done using two by the plant’s DCS/PLC communication objects: hardware. Control input (from DCS to model) and
The model can be New process easily decoupled from configurations and the OTS and be used improvements in as a desk tool for controls can be process or control quickly evaluated, engineers to study validated and potential transferred back to the improvements and plant control system. troubleshoot any This allows for an known process ongoing process of shortcomings. plant improvements.
Cost-effective Performing “virtual’’ evaluation of multiple startups and shut- design or production downs against the alternatives, models, Equipment right-sizing; The most efficient capital cost reduction, operator training tool, Controls design Ongoing plant integrated with process improvements plant design and including improvements can be interactions between tested first on the model equipment, before going on line Pre start-up verification and optimization of the plant’s control system,
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.
The starting point for The first modification made developing the production to minOOcad to turn it into a simulator described here was production simulator was to Metso’s existing flowsheet add multi-ore capability. simulation package . It has been anticipated here MinOOcad. MinOOcad is a that the mine may possess a dynamic simulator; it large number of ore types includes liberation and (up to 20 included here) multi-component separation making up each blend and capabilities (albeit for a that the blends to the plant single ore type) and it allows may be changed frequently the tracking of operating (either on a regular or costs in all pieces of the irregular basis) over a period equipment, so it provides a of several years for good stepping off point for evaluation purposes. further development. Randomness within a mining location
. 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
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.
At the end of the This and subsequent simulation the limits table simulations over longer will show what times and involving a percentage of the time wider range of ore blends each piece of equipment suggest that the ball mills was at or above its limits. are in fact the bottleneck Identifying the bottleneck, to increasing tonnage to making a change, this plant. 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.
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.
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
Elements of good layout in the logical sequence of• There are certain basic the process. Not only will principles to be observed this make for simpler when striving for good plant plant control and layout. These are: maintenance, but it will The layout must be clear also enhance the plants and logical. Each step of aesthetic appeal, making the process should it a pleasanter working occupy a clearly-evident environment. area, and these areas should follow each other
Transportation Safety and well-being of requirements must be personnel must be maximized. minimized, whether Security must be horizontal maximized. or vertical. This applies to Adequate provision must everything that has to be be made for plant moved to, within, expansion. or away, from the plant, These requirements are including ore, residue, frequently conflicting, so that the final layout reagents, stores, always represents a materials, energy, people, compromise among them; and of course, products the best design is the one that achieves the best Ease of operation, compromise supervision and maintenance must be maximized.
Metallurgical involvement in Preparation for the construction phase commissioning, concurrently It is highly desirable that the with the construction phase, or official who will be in charge even earlier if possible, the of plant operation, and, if manager designate will have possible, his second-in- to devote much of his time to command, should be involved preparing for plant startup, for in the design, construction and this will be uniquely his commissioning process at as responsibility 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.
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
Cold commissioning In short, it is the stage in means running the which the plant section section without process is brought to the state material in it. For where it appears to be example, in capable of handling the commissioning a mill process stream circuit, the mills, feed reasonably efficiently, belts, etc. would be run safely and continuously, empty at normal but without actually operating speeds, but having handled normal the mill water process material. reticulation services would be completely functional
After all obvious This is the crucial stage at which the actual process faults which would material begins to pass prevent the safe and through the plant and at reasonably efficient which it becomes evident whether or not the effort of handling of the the preceding months and process stream have years is to be crowned with been eliminated, hot success commissioning can commence.
If possible, commissioning Avoid having ore, should be carried out on waste reagents, etc. in storage rock to reduce the value of for extended periods lockup and loss due to incorrect before plant startup. The processing. 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.
Only partly fill storage Furthermore, if facilities such as stockpiles, bins and tanks before storage has to be startup. Stockpiles, in emptied for fault particular, segregate badly as they are filled, so that unless correction, draw-off occurs reasonably obviously the less concurrently with filling a material to be large core of fines can form which can seriously affect handled the better plant operation and require a long time to eliminate.
Crushers should be Commence commissioning on manual set somewhat coarser control and gradually than designed to introduce automatic begin with and control as operation settles down. gradually pulled up Run-of-mine mills should to correct setting to initially be fed dry (i.e. avoid choking and without discharge) at the damage if they are not highest rate at which rock can be got into them. This is able to handle actual in order to build up a pebble operating conditions load as quickly as possible and to avoid pipeline blockage with coarse discharge.
When the power draft both as regards quantity reaches a maximum and and size distribution, has commences to decline, been built up. In the feed rate should be particular avoid adding reduced to hold the steel if the initial feed is power at maximum and fine, as the steel will dilution water opened. simply retard the buildup Steel grinding media of a pebble load. It is should not be added general experience that until a satisfactory pebble large run-of mine mills load, require as much as six months before they achieve efficient operation
Have a range of sizes of Thickeners should be cyclone spigots and vortex finders available to enable filled to overflowing quick changes for rapid with water before optimization. This applies startup otherwise the particularly to spigots, incremental water whose size is more critical than that of vortex finders. lockup before they Startup vortex finders need overflow can exceed not be rubberized as they the drawdown of the will probably be changed before wearing out. return water tank and the mill water system can run empty
Thickeners should not be to avoid underflow system circulated during startup. blockage, until underflow Because of the higher settling water: solids has rate of the coarser particles, diminished sufficiently to circulation can cause the permit continuous draw-off concentration of sand in the Remember to fill tanks and settled pulp which in turn sumps which would can cause rake overload and normally contain re- trip-out. It is better to keep circulated solutions the underflow pumps required in the process, completely stopped with with a suitable temporary substitute to enable the occasional short spells of process to get started. running (without circulating) Normally clean water is satisfactory
Where the design and/or and a determination is made construction of the plant as to whether the plant is have been carried out by then able to attain the some organization other than specified operating and the owners, it is usual to output targets. include in the contract some . A very important point in form of acceptance run. drawing up the acceptance During this, inputs and clauses is that the acceptance operating conditions of the criteria should be capable of plant are held as close as being measured and that possible to those specified in they be very carefully the Process Design Criteria specified and understood by both parties to the contract.
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.
The most critical Terry Mcnulty (Mcnulty single item in process 1998), in his original design is paper on the subject understanding the noted as one of the feed material the common problems of plant will be treating poor start-ups and plant What is the mine going to failures “Pilot-scale be sending to the mill, testing was incomplete and how does each of these feed types react or may have been metallurgically? conducted on non- representative samples’’
Planning for the estimation People generally, will spend of the start-up parameters for a very large amount of time a new project should begin in estimating the project’s during process development capital and operating costs. and test-work – and Once these are entered into management should be kept the cash flow projection, one aware of this estimate. It will find that someone will should not be left as the last, have to make an estimate of brief step, before completion how long it will take the of the cash flow study project to come up to full design capacity and to projected recovery
If the process chemistry is This rule sounds almost silly. novel, be sure you If you are involved in completely understand it. development of a Even if the process chemistry hydrometallurgical process, is not novel, be sure you and don’t even really believe understand all of the that this could happen. Talk reactions that will take place to someone who has been around a bit longer.
If the use of some new, or The correct place, if you leading edge process, or new possibly can, is to install and type of equipment or test out new stuff is in an anything else new is existing plant, not a brand absolutely essential to the new one economic viability of the New stuff is not bad stuff – plant being designed, go quite the opposite. But plan ahead. If not don’t on spending a big bunch of time and effort getting this sort of equipment of process operating up to design
The things that you spend if you locate and anticipate the most time and effort on potential problems and plan and the potential problems how to deal with them, these that you plan for – never almost assuredly won’t be happen the difficult start-up problems that you have to fight your way through.
You can have it fast. If you are asked, as you no You can have it cheap. doubt have been in the past You can have it correct. and will no doubt be in the future, to do something in an Pick any two 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.
Rule 1: The client is always Talk to operators every right chance you get, learn from Rule 2: If the client is wrong, them. They know a lot more refer to rule 1. about what works than you. The difference between a good plant and a great plant are the operators. Make sure they have input.
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