INFLUENCE OF PROCESS TECHNOLOGY ON THE MANUFACTURE OF MARKET-ORIENTED CEMENTS

摘要

The demands on cement manufacture have risen worldwide. This affects not only the economic aspects but also the environmental compatibility of the production process and the market-oriented quality of cement. For the cement manufacturer market-orientation means not only making appropriate use of the available raw materials and fuels but also satisfying the customers' requirements. Because the energy costs account for a high proportion of the production costs of cement, the cement industry is concerned more than ever with reducing the expenditure on fuels and electrical power. However, in many locations the process engineering potential is virtually exhausted. In recent years the efforts to achieve a further reduction in energy consumption have concentrated increasingly on the replacement of fossil fuels by secondary fuels. A great deal of experience shows that it is possible to fulfil all the quality demands on the clinker, even when using large quantities of secondary fuels, and to produce efficient cements. However, the use of these substances must be closely followed by those responsible for quality control in plants, so that they can react rapidly to any changed conditions which occur and ensure the uniformity of the cement quality. The same requirements apply to the use of secondary raw materials. Alongside the utilization of secondary raw materials and fuels there is also an ecologically and economically initiated change in the development of types of cement taking place at present throughout Europe. CEM Ⅰ cements are being increasingly replaced by CEM Ⅱ cements which, in addition to the clinker, also contain other main constituents. The central problem for process engineering is to prepare and mix suitable combinations of clinker and interground additives so that the performance lies in the same range as comparable Portland cements. The developments on the cement manufacturing side are faced by ever higher demands on the cement quality on the customers' side. Many of the new developments in the field of concrete technology are placing increased demands on the homogeneity and uniformity of the cements. The cement industry is capable of fulfilling these new demands by new and further developments in the fields of raw material processing, of the burning process and of the grinding technology, and not least by the use of new efficient analysis and control technology. The cement user requires not only a constant cement quality but also, to an increasing extent, cements with properties which as far as possible are directed towards specific areas of application. The sharp increase in the sales of cements with individualized properties shows that the cement manufacturers are prepared and able to make such products.