METHOD OF MAKING CEMENT Russian patent published in 2010 - IPC C04B7/00 B02C23/00 

FIELD: chemistry.

SUBSTANCE: method of making cement involves a two-step process of processing cement clinker with grinding on the second step together with the rest of the cement material in an open-cycle mill. At the first step, cement clinker is first crushed in steps in a vertical rotary crusher with preliminary and final grading using a sieving machine into pieces smaller than 5 mm, further in an impact crusher with a vertical shaft and with a built-in separating screen to a fraction of 1.0 mm and, finally, in a horizontal bead mill with a separator for preliminary and final grading to Blaine specific surface area of 2000-3000 cm²/g. Alternatively, the clinker, together with quartz sand taken in ratio ranging from 1:1 to 1:0.5 is crushed using a jet technique in an impact crusher with a vertical shaft. Other components of the cement are preprocessed. Blast-furnace slag is finely ground in a bead mill with a separator to Blaine specific surface area not less than 1500 cm²/g. Slag-ash or flue ash are ground in a roller mill to Blaine specific surface area of not less than 4000 cm²/g. Limestone and gypsum stone are crushed successively in alligator and baffle crushers to pieces smaller than 5 mm. At the second grinding step, all materials ground that way are further ground together in an open-cycle bead mill to Blaine specific surface area of the cement powder of 4000-5000 cm²/g. In order to reduce power consumption when grinding intermediate products making up the cement material and to improve granulometric composition of the obtained cement, a double-chamber bead mill with a centrifugal separator can be used at the second step of the method. Alternatively, materials which are difficult to grind can be ground in a short bead mill with intermediate and final grading, separating the 0-40 mcm fraction from intermediate products and the grinding product and taking the said fraction for final grinding together with the rest of the material in a second short bead mill working in an open cycle.

EFFECT: reduced power consumption through optimisation of the process of grinding materials which are hard to grind and improvement of quality of cement by increasing active surface of basic components.

3 cl, 2 tbl