The Improvement Of Sintering Formula For Red Mud By The Serial Combinatio Process

Nowadays, with the increasingly keen in the manufacturing sector of Aluminum oxide and the grade of bauxite’s gradually becoming worse, especially in China where the bauxite is almost diaspora, the Bayer process is becoming more and more difficult to make good use of the bauxite. However, a new method of aluminum oxide manufacturing-the serial combination process, can deal with the low grade of bauxite and has a great prospects. For the above, in this paper, chemically pure reagents and red mud will be used as raw materials to study the rule and influence of the intensity, alumina leaching property and sintering temperature range of the sintered clinker by changing the sintering formula and sintering temperature. The results are as follows:The repeatability and accuracy of the method that using the high temperature vertical dilatometer to test the range of sintering temperature are being test by using the Na2SO4. It has been found that in the same rate of temperature increase and the same condition of making stock column, the Na2SO4standard deviation of the softening temperature is4.63, and the standard deviation of the melting temperature is3.46, the relative standard deviation of the softening temperature is0.50%, and the relative standard deviation of the melting temperature is0.37%. The two evaluation criterion are both less than2%, that is according with the requirement of the experiments.The range of sintering temperature of the sintered clinker are badly influenced by the ratios of the Na2O-Fe2O3and Na2O-Al2O3. Through the test of serial of the pure reagents mixed material, it was found that the clinker was easier to melting and the rang of sintering temperature was getting narrower with the rising of the ratios of the Na2O-Fe2O3and the influence will continue increasing until the ratios rise to20%. While, with the rising of the ratios of Na2O-Al2O3, the range of the sintering temperature is getting wide and the clinker is easier to sintered. Changing the formula of mixture and the sintering temperature, then testing the intensity, leaching result and the range of sintering temperature, it has been found that the influence of the addition of alkali, calcium and the sintering temperature to the mixture are almost the same. While with the addition of alkali, the leaching result of alkali decreased but alumina rise first then fall down; with the addition of calcium, the leaching result of alkali and alumina decreased gradually. This just because of the reaction of eutectic compound Na1.8Ca1.1(Si6O14). As for the sintering temperature, it has been found that while the sintering temperature rose from1150℃to1250℃, so much liquid phase has been created that the clinker was oversintered. While the sintering temperature is1150℃, the color of the clinker is the same as the raw material, so the clinker was undersintered.Through the results of the experiments, it has been found that when the addition of alkali is enough to react to Na2OFe2O3which account for15%～17%of the clinker except the dosage of the reaction of Na2O-Al2O3, and the ratios of calcium is0.8, the range of sintering temperature is the widest, almost bigger than100℃, while the leaching ratios of the alumina and alkali are over80%.