Study On High Performance Alkali Resistant Castables Used For Cement Rotary Kilns

In recent years,alkali resistant castables as inner lining have been increasingly used for cement rotary kilns.In the last ten years,many precalcner(PC) kilns and preheater(SP) kilns have been brought on line in China.High working temperature,fast kiln speeds,sophisticated mechanical structure and alkali, sulfur volatility resulted in serious alkali attack, as a result, castables working condition becomes increasingly bad. Especially transitionN cooling strip, kiln cover of precalcner kilns ,in order to increase serving life of castables, to reduce production costs,it is necessary to develop alkali resistant castables.As the development of scince and technology,the non-metallic refractories with high alkali attack and high sthength are needed for cement roary Industry,so studying on high performance alkali resistant castables are contributive to the development of cement industry.The author introduced the states of refractory used for cement rotary castables and discussed the development of alkali resistant castables. Based on the history of alkali resistant castables, the author designed four groups proportioning that the slurry of calcium aluminate cement was prepared using binders and burned fireclay as main starting material,microsilica, feldspar, powder of porcelain as additive.In the paper,the influence of grain grading on the compactness tightness accumulate pile was summarized,effects of addition of additive on modulus of rupture, compressive strength, permanent linear and mechanical properties of alkali castables used for cement rotary kilns were studied.Based on the analyzing results of the mechanical performance,the corrosion of alkali resistant castables was mainly discussed.Some suitableaddition is very important to the properties of alkali resistance.The study results show that additive can improve the properties of alkali resistance, the optimum addition of microsilica is 5%, 3~5% potash- feldspar or 5% albite, 2% powder of porcelain.The modulu of alkali castables is up to 13.82Mpa.By the means of SEM, EDAX, analyzing the microstructure, corrosion of alkali castables of sample, the results show the glaze is founded on the surface of sample under experimental temperature, the glaze composition is kaliophilite,around the kaliophilite is liquid,so the sluggish liquids build up the gaps of sample and stop alkali to enter the inner of sample , the properties of alkali resistance get better results.