Using the alumina thermodynamic database, thermodynamic calculations were performed on the relevant chemical reactions in the firing process of the high-iron red mud charge, and on this basis, the sintering process temperature, the firing time, the charge ratio and other firing conditions for the high-speed iron red mud were studied. Burning effect of the charge. The results of the study indicate that the amount of calcium in the red mud charge can be varied within a wide range, and insoluble salts may be formed during the firing process, leading to a decrease in the dissolution rate of alumina in the clinker: prolonging the firing time and adding ingredients Sodium ferrite content is conducive to sintering: The preferred ingredients for the high-iron red mud charge are: Clinker Na = O · Fe203 mass fraction of 10O / ~ 12%, the molar ratio of calcium and iron is 1. o~1.2: The sintering process conditions are: temperature is l000-1 050°C, and firing time is 30--40 min. Under better mixing and firing conditions, when the alumina content in the clinker is about 15%, the recovery rate of AI203 in the clinker can reach 85~/o~90%.
In China's Hunan, Guangxi, and Shanxi, there are certain reserves of high-grade iron medium grade bauxite, this ore is suitable for the production of alumina using the Bayer-Sinter series method. That is, most of the Al2O3 in the ore is recovered using the simple, economical Bayer process. The high-iron red mud produced by the Bayer process is then treated with a sintering process to further recover the Al2O3. The iron-rich slag after the aluminum recovery can be used as a raw material for ironmaking. However, so far, there are still technical problems in using the sintering method to treat the Bayer red iron mud. Although people have conducted a lot of research on the comprehensive utilization of red mud from Bayer Law Plant, such as the use of acid leaching of red mud to prepare inorganic flocculants such as polyaluminum ferric chloride, polysilicic acid iron and polysilicic-iron aluminum, and high-speed iron. Red peat-based direct roast reduction and recovery of metallic iron [as well as production of cement with red mud, etc., but these studies are mostly in the experimental or semi-industrial experimental stage, and mainly focus on the recovery of iron and other rare metals, and the use of sintering There is very little research on the Bayer method for recovering alumina from high-speed iron red mud. Red mud agglomerates are characterized by a high content of sodium ferrite and calcium ferrite, while a low content of sodium aluminate tends to form a fusible eutectic. For such charge materials, the firing temperature range is narrow and the melting temperature is not high, resulting in difficulty in firing. At the same time, if the traditional soda-lime charge is used for sintering, it will produce insoluble ternary compounds containing Al2O3 and Na20, reducing the recovery of alkali and alumina. Therefore, the high-iron red mud charge needs to be blended with more lime, so that a part of the iron oxide in the charge is combined with the lime to form calcium ferrite (2CaO-Fe2O3 or CaO·Fe2O3). In addition, iron oxide and soda produce sodium ferrite. . The author of this article used the thermodynamic database of alumina to calculate the thermodynamics of the relevant reactions in the firing process of the high-iron red mud charge. Through experiments, the sintering temperature, the calcination time, the charge ratio, etc. were used to obtain the clinker after burning the high-iron red mud charge. The effect of the dissolution rate of medium alumina is expected to obtain better process conditions for the recovery of alumina from the high-iron red mud by sintering.
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