Cement Industry Profile

Current installed capacity of cement in the country is 64 MnT/year. Total current domestic cement demand in 1990-91 was 40 MnT. The expected demand projected upto 1994-95 is 65 MnT.

Large plants have 92% share of the total capacity, the balance is with mini cement plants. Of the total capacity 84% of plant capacity is in private sector and balance in public sector. Three states M.P., A.P. and Rajasthan together account for 50% of the industry’s capacity.

At present 64% of the capacity is in large size kilns beyond 1000 tpd. Out of this 3000 tpd and above capacity plants form 42% of the capacity. The standards size of the kiln now is 3000 TPD.

Energy efficient dry process plants account for 81% of the industry’s production with wet process constituting around 16%. The balance 3% is semi dry/wet process plants.

Majority 95% of the production is in rotary kilns while less than 5% is in vertical shaft kilns which is generally in use for mini cement plants.

OPC (ordinary Portland Cement) account for 70% of the production. PPC (Portland Pozzolana Cement) for 19% and PSC (Portland slag cement) for 10%. The percentage of OPC has increased to 70% from 21% in 1981-82.

Manufacturing Technology Status

Raw material Preparation Process

Currently mining is generally done with semi-mechanized methods. Computerized mine planning is now being used by few modern plants. Most of the crushing operation is performed with multistage crushers of small capacity. New plants are now shifting to single stage impact crushers. Transportation of the material from the mines is generally with dumpers. Some of the plants are now shifting to belt conveyors using inpit crushing.

RM grinding technology has progressed from the use of open circuit ball mills to close circuit ball mills with high efficiency separators and improved mill internals. Vertical roller mills have now firmly established themselves for these operations.

Use of computerized on line X-ray analyzers for raw mix optimization has become an essential feature for all modern plants.

Burning Process

All plants commissioned after 1970 have been on dry process kilns. From conventional 4-stage preheater kiln system the current trend has been towards New Suspension Preheater (NSP) kilns with precalcinator having 5-stage preheater systems. Of the total capacity 44% is accounted by NSP) kilns, 25% by SP kilns, 16% by long wet process kilns and balance by other.

Most of the modern plants have now adopted computerized kiln control system with few of them having gone for expert systems.

Clinker Grinding

Currently most of the plants are using close circuit ball mills for cement grinding with mechanical separators. Many are shifting to high efficiency separators, improved mill internals and modified flow control diaphragms.

Energy Consumption Pattern

The current energy bill is approx. Rs. 2000 crores in power and fuel (12 million tons of coal/year and 7x106 units of power/year) with roughly equal share of both power and fuel in value.

Coal constitutes almost 99% of the total fuel used in the cement production. In case of power almost 17% of the cement production is through captive power sources requiring around 54 million liters of diesel.

Current Energy Consumption of India compared to World average is indicated below:

Among various countries, Japan Probably exhibits the lowest average thermal energy consumption of 710 kcal/kg and 103 kwh/t for the dry process.

Our energy consumption is almost 12% higher then world average and 17% higher than the best managed countries for dry process. Roughly 15-20% of our total capacity is operating at the world average standards of efficiency.

Among the various process centres in the plant almost 100% of thermal energy is consumed by kilns whereas for power almost 2/3rd consumption is for grinding operations of raw material, cement, and coal.

The energy consumption performance over the year indicated that average heat and power consumption have come down drastically. There has been on an average 2.5 % reduction in specific energy consumption over the years as indicated.

The reduction has generally been due to technology improvements i.e. shifting to SP and NSP kilns from long dry kilns, computerized control, optimization of kiln performance, switching to vertical roller mills, use of high efficiency separator and improved mill internals etc.

Specific energy consumption varies widely from plant to plant depending upon individual specific conditions. The factors effecting energy performance are plant capacity, capacity utilization, technology level, control system, product mix, in addition to may other external factors like quality of raw material (lime), coal and power supply etc. accordingly fixing up of energy consumption norms is a very difficult exercise and has to be based on in depth studies.                                               Back