Economical, finely controlled cement production

Abstract

Method and apparatus for manufacturing portland cement characterized by a plurality of steps. First, there is introduced into the feed end of a rotary kiln at a first rate a first mixture containing calcareous material for the cement; and at a second rate a second mixture including at least one of argillaceous material and siliceous material for the cement. Either or both mixtures may be coarsely ground. Next, there is introduced into the combustion zone of the kiln at a third rate a third mixture and a fuel, the third rate of the third mixture being complementary with the second rate of the second mixture and the first rate of the first mixture so as to form a balanced cement clinker for the cement, the cement clinker being discharged from the discharge end of the kiln for further processing into the desired final form of the cement. Also disclosed are more specific embodiments including respective sampling and analysis procedures at a plurality of points in the kiln system and the respective altering of proportions of the mixtures to maintain an exceptionally high degree of on-line control over the quality of the final cement clinker; the admixture of the first and second mixtures with slurry for a combination process that has the advantages of both the wet and dry processes; the manufacture of special purpose cement; and the specific apparatus and advantages.