Location & ImportanceLocation There are 20 cement industries producing 1.8 million tonnes of cement. The plants are located in Hazara, Cherat, Jhelum, Thatta, Kohat and Dera Ghazi Khan districts, and at Daudkhel, Rohri, Hyderabad, and Karachi.Importance• There are many favourable factors for the development of cement industries locally• Availability of raw materials(limestone and gypsum)• Good domestic market with high demand from the construction industry• Natural gas is used as a cheap fuel
The main raw materials used in the cementmanufacturing process are limestone, sand ,shale,clay and iron ore. The main material, limestone, isusually mined on site while the other minormaterials may be mined either on site or innearby quarries. Another source of raw materialsis industrial by-products. The use of by-productmaterials to replace natural raw materialsis a key element in achieving sustainableDevelopment.
Processes involved• Mining of limestone requires the use of drilling and blasting techniques.• The blasting techniques use the latest Technology to insure vibration, dust, and noise emissions are kept at a minimum.• Material is loaded at the blasting face into trucks for transportation to the crush ing plant.• In the wet process, each raw material is proportioned to meet a desired chemical composition and fed to a rotating ball mill with water.
•Whether the process is wet or dry, the same chemicalreactions take place.• Basic chemical reactions are: evaporating all moisture, andreacting the calcium oxide with the minor materials (sand,shale, clay, and iron).• This results in a final black, product known as "clinker"which has the desired hydraulic properties.• In the wet process, theslurry is fed to a rotary kiln.•The rotary kiln is made ofsteel and lined with specialrefractory materials toprotect it from thehigh process temperatures.
• In the dry process, kiln feed is fed to a preheated tower.• Regardless of the process, the rotary kiln is fired with an intense flame, produced by burning coal, coke, oil, gas or waste fuels.• The rotary kiln discharges the red-hot clinker under the intense flame into a clinker cooler.• The clinker cooler recovers heat from the clinker and returns the heat to the preprocessing system thus reducing fuel consumption and improving energy efficiency.
•The black, clinker is stored on site in silos or clinker domesuntil needed for cement production.•Clinker, gypsum, and other process additions are groundtogether inball mills to form the final cement products.•Cement can be distributed in bulk by truck, rail, or shipsdepending on thecustomers needs.
• Production of cement is a continuous process. Raw materials are dried, ground, proportioned and homogenized before being burnt in rotary kilns. The resulting Product clinker is pulverised with gypsum at the grinding stage to obtain cement.
The finished cement is then pumped into cement silosfrom where it goes to packing plant for bag and bulkloading. Bulk cement is loaded into special tank trucks fordelivery to customers portable silos at construction sitesor is trucked to Indocements port facilities.Through road tankersand rail wagons.
Products and usesMotor for bonding bricks is madeup of one part by volume ofcement powder with 3-6 parts ofsand, and the minimum of waterto make the minimum workable. Cement and sand can alsobe used to produce a thin skin or render, to protect theoutside of the buildings. The most important use of cementis making concrete, which is used to stick together a mixtureof sand and rock fragments, i.e. aggregate.
Problems faced by the industry• The major factors driving the need for process optimization in the cement industry are the high costs of milling and the effect of particle size on product quality.• With around 1% of the world’s electrical energy used in crushing and grinding cement, all producers experience financial and environmental pressures to reduce energy consumption through process optimization.
• Over grinding uses excess energy, so it is important to ensure the maintenance of an optimal particle size distribution during the production process. Particle size controls the final strength of the cement and so needs careful monitoring at the time of manufacture.• Improving consistency, reducing over grinding, and adhering to tighter specifications are all process optimization challenges for cement manufacturing.• high frequency of power failures, shortage of coal, inadequate availability of wagons for rail transportation, limited availability of furnace oil were the irritants which the industry was confronted with. However, the industry is well placed today as compared to the past.
Problems faced by the Environment• Emission Of Harmful Gases In Air• Noise Pollution• Soil Pollution
Calcium NOV 2003/Paper 2/Q:3 :: Sulphate powdered coal (gypsum) X process B process CClay or shale process AQ3: (a) rotary kiln[i] Name the Inputs shown?  cement[ii] Name the important input X and state amajor source of that raw material. [iii] Give the letter and the name of 2 of theprocesses A , B , C. 
[iv] Why is cement so important for thedevelopment of Pakistan?  NOV 2005/Paper 2/Q:4(c)[i][ii]Q: [i] Give A location in Pakistan for theCement Industry? [ii] State TWO inputs and TWO Outputsof The Cement Industry? 
Questions Look at the fig. below, which shows a number of factors contributing to the development ofthe cement industry in Pakistan. Special Machinery Markets Factors influencing Raw development Labour of cement Supply Material industry Energy Supply Using the information in fig. and from your own studies, explain why the cement industry hasdeveloped at a number of locations in Pakistan during recent years.  June 91/ P2 / Q4(c)