03-25-2014, 11:38 PM
Modern portland cement is made today from a mixture of limestone, sand, aluminum, iron,gypsum and "other ingredients". The limestone is crushed to a fine powder in ball mills and baked in rotating kilns at 2700 degrees F, which is where the coal came in.
Prior to the advent of plentiful electrical power from a grid and the availability of natural gas, coal fired the the boilers that ran the machinery and also provided the heat necessary to bake the limestone.
A hypothetical cement plant thus needs many different loads which are kept separate, since the actual mix depends on the specific customer order. Aggregate does not get added unless the mix is bagged for sale as ready-mix concrete.
Prior to the advent of plentiful electrical power from a grid and the availability of natural gas, coal fired the the boilers that ran the machinery and also provided the heat necessary to bake the limestone.
A hypothetical cement plant thus needs many different loads which are kept separate, since the actual mix depends on the specific customer order. Aggregate does not get added unless the mix is bagged for sale as ready-mix concrete.