The cement would be manufactured using Dry Process with rotary kilns, 5/6 Stage Suspension Pre-heater and Pre-calciner. The process would essentially involve the following:

Raw material preparation

The mined lime stone shall be fed to the crusher with the help of dumpers and the crushed limestone will be transported to the stockpile at plant site by belt conveyor/pipe conveyor. Pre-blending of limestone in stockpile will be done to even out the variation in the quality of materials being received from the mines. Limestone, iron ore and shale shall be transported to the raw mill hoppers for Raw Mill Blending. The process of raw milling in continuous blending–cum storage silo of 16000 tonne capacity would be done to ensure consistency in chemical configuration and particle-size for optimising fuel efficiency in the cement kiln and for imparting strength to the final concrete product. In the dry process, the raw material is dried using impact dryers, drum dryers, paddle-equipped rapid dryers, air separators, or autogenous mills or during the grinding process itself. The raw milled material would then be transported to the blending silo using a set of air slides and bucket elevators. The blending-cum-storage system in the silo shall further reduce the quality variation in the raw material. The gravimetric flow control system for kiln feed shall be installed below the silo to avoid a separate kiln feed building.

Pyro-processing

The pyro-processing system involves drying or preheating, calcining (a heating process in which calcium oxide is formed), and burning (sintering). The raw mix in the form of powder would be fed to the rotary kiln. The kiln system would comprise of a 5/6 stage cyclone pre-heater, pre-calciner with tertiary air duct, kiln, reciprocating type new generation grate cooler and a pan conveyor. The pyro-processing would involve heating of the raw mix to produce cement clinkers as the product of the chemical reaction between the raw materials. These clinkers would be in the form of hard, gray, spherical nodules with diameters ranging from 0.32 - 5.0 cm (1/8 - 2").

Clinker cooling

The clinker cooling operation would recover up to 30% of kiln system heat, preserve the ideal product qualities, and enable the cooled clinker to be maneuvered by conveyors. The clinker coolers that would be used are reciprocating grate, planetary, and rotary. Air sent through the clinker to cool would be directed to the rotary kiln nourishing fuel combustion. Based on the cooling efficiency and desired temperature, the amount of air used in cooling process would be approximately 1-2 kg/kg of clinker. For dedusting of cooler vent gases an Electrostatic Precipitator (ESP) has been considered. The clinker shall be transported to one of RCC silos of 330000 tonne capacity from cooler by the pan conveyors.

Clinker storage

Although clinker storage capacity is based on the state of the market, a plant can normally store 5 - 25% of its annual clinker production capacity. Equipment such as conveyors and bucket elevators will be used to transfer the clinkers from coolers to storage areas and to the finish mill.

Clinker grinding

During the final stage of cement production known as finish milling, the clinker is ground with other materials (which impart special characteristics to the finished product) into a fine powder. Up to 5% gypsum and/or natural anhydrite will be added to regulate the setting time of the cement. Other chemicals, such as those which regulate flow ability or air entrainment, may also be added. These materials will be sent to cement grinding system comprising of a ball mill with high efficiency separator, then to Close Circuit Ball Mills which perform the remaining grinding. The grinding process would occur in a closed system with an air separator that will divide the cement particles according to size. For collecting the ground material from ball mill and deducting of the vent air, a suitable sized bag filter has been considered.