Experimental Research On Desulfurization Roasting Of High Sulfur Bauxite In Suspended State

With the rapid development of Chinese aluminum industry in recent years, productivity of aluminum has improved continuously. At the same time, the bauxite resources of China have been more lean, fine and miscellaneous, raw ore supplies are tight. But there is still a large number of high-grade, high sulfur content(ST≥0.7) diaspore bauxite which not been fully occupied because of there is no such pre-treatment desulfurization process of industrialization. For getting the pre-desulfurization products met Bayer industrial processing requirements, the paper proposes a new process of roasting bauxite in suspended state, and researches on the desulfurization process of bauxite in suspension equipment by self-design.Firstly, were the basic physical and chemical properties of raw materials analysis and thermodynamic analysis, simulation suspended state studied baking characteristics of bauxite, and provides the necessary parameters for the semi-industrial in suspension firing. On this basis, were studied semi-industrial, to explore the best in suspension calcination process parameters bauxite, the ore roasting and desulfurization results were analyzed and evaluated. We obtained the following conclusions:(1) The A/S of the high-sulfur bauxite used in the test of is very low, the total sulfur content of the sample reached 1.61%, wherein the content of sulfate sulfur 0.50%, and most of the sulfur present in the form of pyrite.(2) Thermal analysis showed that: in the diaspore bauxite roasting process, there are three main reactions, including dehydration reaction, desulfurization reaction and the oxidation reaction. The three basic reactions react simultaneously in 450~600℃.(3) Relative to the calcination temperature, the calcination time has greater influence on the desulfurization rate. Desulfurization efficiency is high before the desulfurization rate is around 70%, then it will be a significant reduction. Improving roasting time and temperature have less affected on the increase of desulfurization rate. Under certain roasting conditions, the majority of sulfur in the bauxite can be removed in a short time.(4) Desulfurization process of bauxite contains pyrite oxidation and sulfate decomposition desulfurization, and two reactions react simultaneously.(5) High solid-gas suspension preheater roasting process can achieved bauxite ore roasting efficient desulfurization and activated when the furnace temperature is controlled above 520℃, the volume of feed is 800kg/h, it is possible to achieve good desulfurization roasting, roasting ore ST is less than 0.45%, S2- is less than 0.06%.(6) With semi-industrial tests, the gas-solid-contact is the most important factor affecting the desulfurization effect.