Cement and Energy

• • Optimization of cement mill air circuits. Installation of mill horns to control cement mill operation. Rationalisation of pneumatic pumps used for cement conveying and enhancement of their capacities. Installation of high efficiency pump in slurry section . Disconnection of two under-loaded transformers and rationalisation of load distribution. Thennal Energy Installation of forced air fan for planetary coolers to improve recuperation efficiency. Optimisation of kiln burner tip velocity. Use of insulation bricks in the calcining and the transition zones of kilns to reduce radiation losses. Design of raw nux with improved burnability index Reduction in slurry moisture. NEW MILL DESIGN FROM F L SMIDTH F L Smidth has unveiled a new design of cement mill, which is rather different from today' s ball mill s, roller presses, vertical roller mills or closed– circuit roller presses. The Cemax system consists of a fully air-swept ring roller mill, with internal conveying and grit separation. The company decided to develop a cement grinding system featuring roller grinding, due to its cost– effectiveness. The Cemax system grinds the material by pressing it between a ring and a roller. The roller rotates between dam rings fitted on the sides of the grinding ri ng, ensuring uniform compaction and grinding. The mill rotates at subcritical speed, and scooping devices at both ends of the ring ensure effective internal conveying of the material being ground. The material then leaves the scooping devices at various points, ensuring good distribution of the material in the air stream between the air inlets and outlets. The process air enters through two inlets at either end of the mill and leaves through an outlet at either end of the mill. The air passes the falling material and carries the finer particles to the Sepax separator, in which final classification takes place. Cemax ground cement tends to have a steep particle size distribution. FLS claim that the system can bring a power saving of up to 40 % and that single units can be manufactured with an output capacity of up to 300 tonnes of cement per hour. [Courtesy: International Cement Review, June 1996) Comparative specific power consumptions for alternative grinding installations OPC Cement ground to Blaine 300m2/kg Power Consumption, kWh/t Closed Circuit CEMAX Ball Mill Ball Mill 30.0 - CEMAX - 18.0 Separator 0.4 0.6 Separator Fan 2. 1 3.9 Mill Fan 0.7 0.2 Aux. l.O 2.0 Total kWh/t (net) 34.2 24.7 Power saving, % - 28 % [Courtesy: International Cemem Review - November 1996] 11