O processo produtivo do cimento portland

Abstract

This monography intends to describe the production process of portland cement, step by step. Portland cement is manufactured from 75-80% limestone and 20-25% lay. After mining and primary crushing, limestone and clay are sent to the pre-homogenization step. The mixture of them is called argical and is stockpiled and homogenizated in a long pile. After homogenizated, argical is sent to the secondary crusher. The crushed product is screened in a 0,050 mm (50 m) sieve. The oversize is sent to a mill, which can be a ball mill or a vertical mill. The mill product is named flour fine (unbleached flour) and is stocked in a bin. This flour is fed to the first step of a battery of heat recovery cyclones. The temperature rises from 45 to 70ºC to 440ºC, then to 650ºC. In the third step it raises to 770ºC. In the fourth step it is at 900Cº and is fed to the calcining kiln. In this rotary kiln the flame temperature is of about 2000°C. The final product is the clinker, cement ball, at about 1450ºC. It is cooled for heat recovery and stored in bays before grinding. At the mill slag, pozzolana (and gypsum) are added according to the desired cement formula.