Stringent requirements are imposed on portland cement clinker. It should exhibit a complex of certain physical and mechanical properties. Improvement of quality of portland cement clinker mainly depends on the improvement of manufacturing process of its production, intensification of production processes, development of radically new, more efficient and economical methods for the production of portland cement clinker.
In the production of portland cement clinker, the composition of raw materials, methods of preparing raw materials, processes of decarbonization and roasting of raw mixes are of a predominant importance.
Known in the art are various processes for the preparation of portland cement clinker which differ by the composition of raw mix, method of batching and homogeneization, binder material used for pelletizing, gasodynamic and temperature conditions, various production steps used in carrying out the process, and a number of other features.
Known in the art is a process for the preparation of portland cement clinker, wherein the process of manufacture is intensified by modifying the steps of the process grinding and homogeneization of raw mix are performed in the decarbonization zone of a rotary kiln.
In another process for the preparation of portland cement-clinker, in order to intensify the clinker formation process and accelerate the decarbonization processes, additional steps are used: thus fuel is additionally burnt in the layer of material in the decarbonization zone, and the decarbonized mix is abruptly heated to 1400.degree.-1500.degree. C.
However, these processes are associated with a low degree of decarbonization and high-temperature roasting conditions.
Known in the art is also a process for the preparation of portland cement clinker by grinding limey, clayey and iron-containing components to obtain a mix which is homogeneized and pelletized to produce pellets of 8 to 12 mm size with a moisture content from 12 to 15%. The material is then decarbonized on a calcination grate at 800.degree. to 1000.degree. C. The material is subsequently fed to a roasting kiln. The roasting is effected at 1450.degree. to 1500.degree. C.
This process is characterized by high thermal efficiency, however, in conducting the process, the resultant clinker exhibits inadequate strength because the process cannot ensure the production of high-strength pellets, and rather low degree of decarbonization is achieved. Besides, the process features high roasting temperature and specific fuel consumption.