Study On MgO-ZrO₂ Refractory For Burning Zone Of The Cement Kiln

From the end of 1970s, because of the improvement of environmental protection and the need of development green industry, there are great changes have happened to the basic bricks used in cement rotary kiln. The cause of the change is elimination of chrome — pollution and protection of human living environment. As the key refractory in the burning zone of the cement rotary kiln, the Magnesia — chrome bricks form the water — soluble compound R₂Cr(VI)O₄ or R₂[SCr(VI)]O₄ which are harmful for human being and animals under the action of alkali and sulfur . The poisoned compound could be compelled through the wasteful gas and dust. The bricks that had been used suffer the rain and the poisoned compound could pollute environment, specially the water. The Magnesia — chrome bricks are gradually limited in developed countries, and would be instead.The first material instead of the magnesia — chrome bricks is Magnesia — dolomite bricks. The Magnesia — dolomite brick has the appetency and good stability of chemistry, which result in the superior coating adherence and corrosion resistance to cement raw materials. It also has the disadvantages of hydration and bad thermal — shock resistance. Spinal brick has the good thermal — shock resistance, however it has the disadvantages such as the bad coating adherence and high heat — conducting rate. All these disadvantages cause they could not completely instead of the Magnesia — chrome bricks which is used in the sinter-zone of the cement rotary kiln.We use 95 sintered magnesia, 96 fused magnesia, c-ZrO₂, Zircon (ZrO₂·SiO₂), Zr(OH)₄gel as the raw material for the research of MgO-ZrO₂ series refractoriness in sinter zone of cement kiln. The experimental result is: the specimens that is made up of 96 fused magnesia fine power and 95 fused magnesia grain is better than the specimens which is made up of 95 sintered magnesia fine power and 95 fused magnesia grain. In the three additive ways of ZrO₂ the cement corrosion resistance of the specimen which is addicted with C-ZrO₂ is the best, and the cement adherence is the worst;however the specimen which has the best cement adherence, its cement corrosion resistance ability is the worst. Thus according to the experimental phenomenon, we can gain the conclusion: the performance of the specimen that is addicted with Zr(OH)₄ gel is better, its compressive strength and the fold strength are high. What we had researched makes a useful attempt in the procession of free chrome for cement refractoriness in china. And it also have guideing function for theory and value in use for production in the procession of free chrome for cement refractory in china.