GRINDING TECHNOLOGY FOR CEMENT PRODUCTION - DEVELOPMENT, CURRENT SITUATION AND OUTLOOK

The efficiency of comminution in ball mills is very low. Significantly higher energy utilization is achieved in, roller grinding mills and, in particular in high-pressure grinding rolls. To increase the perform ance of existing grinding plants it can. therefore often be economical ly advantageous to carry out the grinding in two stages and to place a roller grinding mill or high-pressure grinding rolls upstream of the ball mill. However, the highest energy utilization is achieved if all the fine grinding can be carried out in a roller grinding mill or high -pressure grinding rolls. Vertical roller mi Ils with integral classif iers have been in use for many years, primarily for drying and grindin g raw materials for clinker burning. The grinding elements and mill op eration are modified when the mill is used for finish grinding cement. In spite of the relatively high investment costs new plants with vert ical roller mills offer particular advantages when very moist material s have to be processed. On grounds of economy it may be appropriate fo r the cement components, or preliminary mixtures of suitable compositi on, to be ground separately. Products from roller grinding mills and h igh-pressure grinding rolls have narrower particle size distributions than those from ball mills.