Depending on the nature of the preparation of raw mix the following methods of Portland cement production are distinguished: wet, dry and combinative one. Each of these methods has its own features, strengths and weak points. In mid-developed economies cement plants focus on wet method, while more developed companies that either produce or closely cooperate with manufacturers, like a UK-based Telling Company, actively utilising hydraulic lime, lime mortar and Portland concrete solutions, are restructuring the technology to more economical fuel consumption – dry and combinative methods.
In the wet process the raw material mixture is ground in a ball mill in the presence of large amounts of water (up to 36-42% by weight solids) to give a flowable mass, which is called sludge. From sludge basin-7 mass is directed to firing in the rotary kiln wet method is useful when used as components of chalk, clay crude that reduces power consumption for grinding the raw material mixture.
In this method the transportation of raw materials and stirring the mixture is facilitated, but the fuel consumption on firing it in a furnace is 1.5-2 times more resource-intensive than in the dry process. In the dry method, dry powder is prepared through mixing raw material (the so-called raw meal), which is calcined in a rotary kiln.