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Indian cement industry a technology perspective


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Indian cement industry has passed through many ups and down. It was under strict
government control till 1982. Subsequently, it was partially decontrolled and in 1989, the
industry was opened for free market competition along with withdrawal of price and
distribution controls. Finally, the industry was completely de-licensed in July 1991 under the
policy of economic liberalization and the industry witnessed spectacular growth in production
as well as capacity.

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Indian cement industry a technology perspective

  1. 1.    Indian Cement Industry: A Technology Perspective Dripto MukhopadhyayIndian cement industry has passed through many ups and down. It was under strictgovernment control till 1982. Subsequently, it was partially decontrolled and in 1989, theindustry was opened for free market competition along with withdrawal of price anddistribution controls. Finally, the industry was completely de-licensed in July 1991 under thepolicy of economic liberalization and the industry witnessed spectacular growth in productionas well as capacity. Over time, the industry has also witnessed spread of the plants in severalregions of the country as presented in Table 1- 2, which were previously concentrated inclose proximity to the raw material.   250 Capacity and production in MT 200 150 100 50 0 1950 1980 1900 2000 2009 Capacity Production   Fig 1. Capacity, Production and Capacity Utilization in Indian Cement Industry  T3 ‐ 146   
  2. 2.    250 200 Consumption in MT 150 100 50 0 2003‐04 2004‐05 2005‐06 2006‐07 2007‐08 2008‐09 2009‐10   Fig 2. Cement Consumption in India 100 87 83 80 74 67 75 60 40 20 0 1950 1980 1900 2000 2009 Capacity Utilization Fig 3. Capacity Utilization in Indian Cement Industry T3 ‐ 147   
  3. 3.    Table 1: Distribution of Cement Plants with Installed Capacity above 0.50 MnT Installed Capacity above 0.5 Million Tonnes State No. of Plants Percentage Share Andhra Pradesh 32 21.33 Assam 1 0.67 Bihar 1 0.67 Chhattisgarh 8 5.33 Gujarat 11 7.33 Haryana 2 1.33 Himachal Pradesh 5 3.33 Jharkhand 3 2.00 Karnataka 8 5.33 Madhya Pradesh 11 7.33 Maharashtra 9 6.00 Meghalaya 1 0.67 Orissa 4 2.67 Punjab 2 1.33 Rajasthan 18 12.00 Tamil Nadu 17 11.33 Uttar Pradesh 8 5.33 Uttarakhand 2 1.33 West Bengal 7 4.67 Table 2: Distribution of Cement Plants with Installed Capacity Less than 0.5 MNT Installed Capacity less than 0.5 Million Tonnes State No. of Plants Share in % Andhra Pradesh 3 9.09 Assam 1 3.03 Chhattisgarh 2 6.06 Delhi 1 3.03 Gujarat 3 9.09 Haryana 1 3.03 Himachal Pradesh 1 3.03 Jammu & Kashmir 1 3.03 Jharkhand 2 6.06 Karnataka 3 9.09 Kerala 2 6.06 Madhya Pradesh 1 3.03 Maharashtra 1 3.03 Meghalaya 3 9.09 Punjab 1 3.03 Rajasthan 2 6.06 T3 ‐ 148   
  4. 4.   Technologies Adopted by Indian Cement IndustryGenerally cement manufacturing process involves following stages: 1. Quarrying raw materials 2. Crushing 3. Pre-homogenization and raw meal grinding 4. Pre-heating 5. Precalcining 6. Clinker production in the rotary kiln 7. Cooling and storing 8. Blending 9. Cement grinding 10. Storing in the cement siloIndia is the second largest cement producing country in the world with a distinction ofoperating plants with varying capacity and varying technologies. Some of the modern plantscan be compared to the best plants in the world in terms of variety, quality and energyefficiency. Indian cement industry remained proactive in adopting technologicaladvancements taking place all over the world. The share of energy inefficient wet processplants had slowly decreased from 94.4% in 1960 to 61.6% in 1980. Currently, the share ofwet process is only about 1% according to industry sources.During the 80s and 90s, major technological advancements took place world over in designof cement plant equipment/systems primarily in the following major areas: a) Pre-calcination b) High pressure grinding c) Automation in process control d) High efficiency particle separation e) Clinker coolingThese resulted in significant transformation of the production process globally. The Indiancement industry closely followed the international trend. Energy conservation has been theprime objective that propelled major technological changes in the industry. A few recenttechnologies that helped Indian cement industry to consolidate in sustained energy savingsare broadly discussed below.Raw Material Grinding: Raw material grinding is a critical mechanical operation thatdetermines the sizing of equipment in cement plant. This process consumes about 20% of T3 ‐ 149   
  5. 5.   total energy consumed in the plant. Depending on the raw materials’ physical characteristics,various grinding systems are used in Indian cement industry: a) Ball mills b) Vertical Roller Mills (VRM) c) Ball mills with high pressure grinding rolls. d) High pressure grinding rolls e) Horizontal roller millsVertical roller mills have been widely accepted for combined grinding and drying of moistraw materials due to their excellent drying capacity and low energy consumption. While anumber of plants are still using ball mills, many have installed pre-grinders like roller press toimprove energy efficiency. Here, the extent to which the roller press is loaded determines theefficiency of the grinding circuit. Use of roller press alone as a finish grinding equipment togive the final product is also a new development.Horizontal roller mill is yet another improvement in grinding systems incorporating theadvantages of vertical roller mill and roller press. An additional advantage with the horizontalroller mill is its low space requirement. A compact horizontal roller mill with an in-builtseparator is now in the process of development. This kind of a mill would eliminate manysmall conveyors carrying material to separator and from separator.The efficiency of the grinding circuit and power consumption of the mill fan largely dependon the performance of the classifier. Perhaps classifier is the part that has undergonemaximum changes and has been the target part for efficiency improvement. A variety of highefficiency classifiers are employed in grinding circuits.Pyro-processing: Pyro-processing section in a cement plant comprises pre-heater, rotarykiln and clinker cooler. This section is considered as the main element of cement plant ascement clinker formation takes place in kiln. This section determines the size of a cementplant as well as sizes of all other equipment. With the introduction of pre-calciners in 80s,the size of cement plant had considerably increased. With technology upgradation, a kiln sizeof 7000 tpd is considered as an economic size which was at the level of 600 tpd in 70s.Pre-heaters can be classified into the following 5 categories irrespective of the manufacturer. • Pre-heater without calciner • Inline calciner with air passing through the kiln • Inline calciner with external tertiary air duct T3 ‐ 150   
  6. 6.    • Separate line calciner • Separate line calciner with inline calcinerCyclones are basic units in a pre-heater system. Efficiency of cyclones depends on pressuredrop and change of temperature of gas across each stage. Introduction of Low Pressure drop(LP) cyclones has brought the pressure drop across each stage to around 50 mm WG fromaround 150 mm WG in conventional cyclones. A typical 6 stage pre-heater with LP cycloneswill have a pre-heater exhaust gas temperature of around 2500C and draught of around 500mm WG. This in turn leads to decrease in pre-heater fan power consumption. The reducedtemperatures at pre-heater exhaust contribute to environmental improvement.The burners also play an important role in determining the thermal efficiency of the pyroprocessing system. There has been a continuous effort on operating the burners with the leastpossible primary air. Multi-channel burners that consume only 5% primary air are being usedin many plants. This leads to a direct thermal energy saving of 15 kcal/kg clinker. Thesemodern burners also facilitate easy flame control in the process.Clinker cooler is also critical for the production process. It has dual functions, i.e. reducingthe temperature of the clinker to an acceptable level for further transport as well as grindingand recover energy from the heat of the hot clinker by heating the cooling air. Mainly twotypes of clinker coolers are used at present in cement industry. They are: a) Grate cooler b) Planetary coolerConventional grate coolers are still used by many plants due to comparatively higher thermalefficiency though they account for several bottlenecks. There have been a number of designimprovements in grate coolers in recent times, mainly on grate plate to improve theefficiencies simultaneously reducing the cooling air intake. More and more cement plantswith conventional grate coolers are retrofitting the coolers with high efficiency coolers. Thishas resulted in low electrical energy consumption in cooling air fans and also in cooler IDfan.Cement Grinding: Cement grinding is another energy intensive operation. Cementgrinding consumes around 25-30% of the total energy consumed in a cement plant. Typicalcement grinding systems in use are:• Open circuit mills• Closed circuit mills T3 ‐ 151   
  7. 7.   • Roller press with open circuit ball mill• Roller press with closed circuit ball mill.• Roller press in finished mode• Vertical roller mill• Horizontal roller millFor many years Ball Mills were in use in open circuit and closed circuit mode. In recent past,roll press as has been introduced and this has led to substantial reduction in energyconsumption. Use of vertical roller mill for cement grinding is also very recent and theperformance results are reported to be encouraging. Horizontal roller mills combine theadvantages of roll press and vertical roller mill. These mills are reported to be highly energyefficient. Horizontal roller mills are best suited for slag grinding.Separator is crucial equipment in cement mill section as it has direct bearing on productionand quality of cement and energy consumption. High efficiency separators are used inmodern cement plants and old plants are also going for a retrofit. Apart from these, auxiliaryitems like mill liners and diaphragms have also been improved continuously over time andthese items in different designs are available contributing to energy reduction in cementgrinding. Table 3: Technology of Indian Cement Industry at a Glance Low Technology Plants Modern Plants Global Technology Mining and Conventional Computer aided Computer aided Material Handling In-pit crushing & Crushing Two stage Single stage conveying Conveying of Dumpers/Ropeway/ Pipe conveyors, Belt Belt conveyors Limestone Tippers conveyors Ball Mills with / without VRM’s, Roller Presses Grinding VRM’s, Roller Press conventional classifier with dynamic classifier Wet Dry Semi Dry Dry 6 stage pre-heater Dry -5/6 stage pre-heater ‐ High efficiency coller -4 stage pre-heater - High efficiency coller ‐ Multi-channel burner Pyro-Processing - conventional coller ‐ Multi-channel burner Co-processing WDF - Single channel burner Co-generation of power Low Nox/SO2 emission technology Continuous Blending Continuous Blending Blending & Batch Blending silos silos silos Storage Multi-chamber silos T3 ‐ 152   
  8. 8.    Dome silos Bag Bag Bulk Packing & Palletiz zing and shrin nk h Dispatch Bulk wrappi ing Relay Logic / Hard Wired d DDC DDC / PLC Process c control Neuroffuzzy expert Fuzzy log expert sys gic stem system m Energy 90-100 kWh/ cem. /t 75-85 kW cem. Wh/t 70-80 k kWh/t cem. consump ption level 900-1000 kca al/kg cl. 700-800 k kcal/kg cl. 675-74 kcal/kg cl. 40 Plant Siz (TPD) ze 300 –1800 3000 –60 000 6000 – 12000Outcome of Techno e ological Cha angesConsequent to grow wing competi ition witness in the post de-contr era, one of the majo sed p rol ordevelopm ments has be the introduction of h een higher grades of cement. The streng parameters gthobtained with moder technolog in India are far high than the BIS specif rn gies a her e fied standard dsfor respective grades of cement. s 80.00 8 60.00 6 40.00 4 20.00 2 0.00 OPC PPC PSC P Others Fig 4 Share in To Product 4. otal tion (in %) Note: OPC - Ordinar Portland Cement, PPC - Portland Pozzolana Cement ry P PSC - Portland Sl Cement C lag  T3 ‐ 153
  9. 9.   Conclud ding Remark and Polic Message ks cyAlmost a cement pl all lants are cur rrently equip pped with hi efficienc dust collection system igh cy mslike Electro Static Pr recipitators. It has been r realized that running the plant in env t e vironmentall lyfriendly w has dire bearing o the profita way ect on ability and im mage of the company. U of blende Use edcement, utilization o waste hea in cemen plant to g of at nt generate elec ctrical energ and use o gy ofalternate fuels are a few exam mples explaining the co oncern of ce ement indus stry not onl lytowards protection o environm of ment but also ecological balancing. There hav been man . ve nyattempts to recover the heat lost in exhaust gas streams of cement plants. With the use of 6 t t s hstage pre e-heaters, hi efficienc coolers a better re igh cy and management practices, th efractory m hequantity of heat lost from the ce ement plants has come down signific d cantly. Now technologie w es able to recov the heat from exhau gas stream from pre-are availa ver ust ms -heater and c clinker coole erand gene erate electric energy. M cal More cement plants in In t ected to ado such waste ndia are expe optheat reco overy system mainly to counterac the powe shortage. As the electrical powe ms t ct er ergenerated from wast heat does not require combustion of any fos fuel, suc an attemp d te s e n ssil ch ptwould en nable the ce ement plant to significan contribu to the m ntly ute movement of reduction i f ingreenhou gases. use 80 % of Production 60 40 20 0 1999 2004 2009 OPC PP PC+PSC Fig 5. Shif in Producti ft ion T3 ‐ 154
  10. 10.    Table 4: Comparison of Carbon E n Emission from Cement M m Manufacturin ng OPC PPC % Ton /t nne % Tonn /t ne Calcinatio on 0.50 60 6 0.3 37 58 Combustio of fuel on 0.24 29 2 0.1 18 28 Use of pow wer 0.09 11 0.0 09 14 Total 0.83 10 00 0.6 64 100 0  VRMs & 300 TPD Kilns 00 1200 TPD 4-ST SP Kilns 4 Low Pressure, Pre- L PC Kilns s Rolle Press & H er High heater h & Ex xpert Effic ciency Separators s Dry Proce Kilns ess High Effici iency Fans, Mechanical Conveyors KW WH/T Cement   Fig 6. Tren of Electric Energy C nd cal Consumption in Indian Cement Indus n strySource: A Adopted from R Raina, S. J. (200 Energy Ef 02), fficiency Impro ovement in Ind Cement In dian ndustry, Nation nal Council f Cement & Building Mater for B rials, paper pre epared for IIPE Programme EC e.  T3 ‐ 155
  11. 11.    1700 120 TPD 4-ST Kilns PC Kilns 1500 Dry Process Kilns Wet to Dry Conversion 1300 5-Stage PC Kilns 1100 6-Stage PC Kilns & Multi Channel Burners 900 High Efficiency Coolers 700 1960 1970 1980 1900 2000 KCAL/KG CL   Fig 7. Trend of Thermal Energy Consumption in Indian Cement IndustrySource: Adopted from Raina, S. J. (2002), Energy Efficiency Improvement in Indian Cement Industry, National Council for Cement & Building Materials, paper prepared for IIPEC Programme.Production of blended cement is also another outcome of the new researches in theindustry.Blended cements are hydraulic binders in which a part of portland cement is replaced byother hydraulic or non-hydraulic materials. They display some superior properties directlyrelated to durability apart from normal properties of Portland cement. It has been found thatfly ash generated in thermal power plants and slag generated in steel plants is suitable formanufacture of blended cements. Fly ash or slag is inter-ground with cement clinker toproduce blended cement. Many developed countries started using such blended cements inlarge quantities in construction of critical structures such as rocket launch pads, sea waterjetties, large dams etc. Production of blended cements directly increases the plant capacitywithout any need for creating additional clinker making capacity. This reduces the limestoneusage and fuel usage in cement plants and in turn lessens the greenhouse gases emissions.Increasing scarcity of good quality coal and power at an attractive price and an everincreasing energy cost to total production cost are forcing the Indian cement industry to lookfor alternate fuels. Use of cheap alternate fuels like lignite, pet coke, rice husk, groundnutshells etc. is in practice now. In some European cement plants the cost of fuel is reported tobe zero due to the use of 100% waste fuels. In fact, in many cases the cement plants are paid T3 ‐ 156   
  12. 12.   for burning the municipal and industrial wastes in such places. Indian cement industry shouldalso look for such alternatives. However, this requires development of infrastructure atcement plant site as well as waste generation and collection infrastructure. T3 ‐ 157