PLANT MODERNIZATION TO REDUCE COSTS AND IMPROVE QUALITY

There was an upward trend in world cement consumption in, 1994. The major growth areas in Asia and Central America again showed growth rates of the order of 6 to 8%. Stagnant markets such as North America and South Africa are reviving. Even in Germany there was a growth of about 3% although about 20% of the total requirement was imported mainly from neighbouring countries in Eastern Europe. Analysis of the capacity figures for kiln lines ordered in 1994 emphasizes the economic boom which has been in progress for a number of years in Asia and Central America. A 7500 t/d kiln line which went into operation in Thailand at Me end of 1994 reached the guaranteed product-ion parameters only a few months later with a specific heat requirement from fuel of 709 kcal/kg clinker. In contrast to the Asian countries the emphasis in Europe is on investment in rationalization and modernization. A new type of cyclone separator, which has downward projecting outlet duct, has been tested successfully and - when used in a multi-stage preheater - leads to a significant reduction in the height of the preheater tower The new generation of grate coolers fitted with Jet Ring plates has proved a success. Many details, as well as the aeration regime, have been improved. The dual-pass cooler introduced last year has also proved successful. In. a 1200 t/d kiln plant the cooler reached ct thermal efficient 78.6% and a clinker exit temperature of 36 degrees C with a cooling air volume of 1.62 m(3)(stp)/kg clinker. There has also been great activity in the field of environmental technology. With the aid of the POLVITEC filter the emission of pollutants from a kiln plant can be almost entirely eliminated Successful tests have now also been carried out on a process for desulphurization of industrial exhaust gases using products from the cement manufacturing process. A total of 48 mills, including 20 tube mills and 18 sets of high-pressure grinding rolls, were sold in 1994. The largest tube mill yet built, with dimensions of 6.2 m diameter x 25.5 m and an installed rating of 11 200 kw, was commissioned in 1994 for grinding gold ore. Combi grinding is now the dominant technology for high-pressure grinding rolls, and roller mills lead the field in raw meal production. The largest roller mill built so far by Krupp Polysius has a grinding table diameter of 6.0 m and a drive rating of 3700 kW: Because of the drying associated with the grinding the roller mill is now preferred for grinding blastfurnace slag. In conjunction with an expert system the mill can be operated at its optimum and with little vibration. In the field of laboratory automation an NLK module has been developed determining the wet slaking curves of burnt lime. A new equipment system for rapid, cost-effective, processing and analysis of material samples has also been introduced under the name of QUICKLAB.