Research On The Digestion Performance Of Floatation Desulfurization Bauxite Concentrate

Abstract:The sulfur-containing bauxite can not be directly used in the alumina production. Flotation process can be used to reduce sulfur content and then concentrate was obtained, namely bauxite concentrate. Plant found some problems when bauxite concentrate was digested, such as poor digestion properties of bauxite concentrate, large amount of lime required for digestion and relatively higer A/S of red mud.In order to solve the problems of poor performance of the bauxite concentrate leaching, the main contents of this paper included the following three aspects:(1) The proper digestion conditions of this floated bauxite concentrate was determined after a series of experiments;(2) Changing the adding way of lime for bauxite concentrate digestion, that is, the lime was transformed into lime milk by sodium aluminate solution, and hence the Al2O3content in dissolution slurry solution increased and the red mud A/S reduced;(3) The use of lye wet milling for the bauxite concentrate could reach the purpose of improving the digestion yield.The effect of the leaching-temperature, quantity of lime, leaching-time, alkali and sulfate ion on digestion rate of the bauxite concentrate was studied by digesting bauxite concentrate in steel bomb autoclaves, combined with the means of chemical analysis, X-ray fluorescence spectroscopy and high-frequency infrared carbon and sulfur analysis. The result showed that:the leaching-temperature had the most influence on the digestion rate of bauxite concentrate, and the quantity of lime was the second. The higher sodium sulfate content in sodium aluminate solution resulted in reducing the digestion rate of bauxite concentrate and increasing the carbonate content in sodium aluminate solution.The use of lime milk instead of lime added into the digestion process increased the Al2O3content in dissolution slurry solution and reduced the red mud A/S.The leaf filter cake had the same composition with the lime milk. The red mud A/S did not changed when the leaf filter cake was added into the digestion process, and it proved that the leaf filter cake could be re-used.The use of wet milling for the bauxite concentrate increased the digestion rate of bauxite concentrate, shrinked the average particle size of the ore and reduced the surface attachment. The Al2O3content in dissolution slurry solution increased14g·L-1and the red mud A/S reduced to1.10from1.24. The quantity of lime reduced to6%from10%under the same digestion conditions.