Experimental Study On Desiliconization Of Bentong Bauxite Deposit In Yunnan Province

Although China is abundant with resources of bauxite,and ranks fourth globally in reserves of bauxite,most of bauxite is diaspore,which has a feature of high-silicon,high aluminum and low ratio of A/S,finely dispersed in the gangue,and associated with many other minerals.Yunnan is a province in China rich in bauxite resources,the resources have a content of mud up to 45%-55%,at an even grade of 53.72%of Al₂O₃ with a A/S ratio of 5.when it is taken as material for production of aluminium oxide,a good profit can't be produced,what has an effect on the development of aluminum oxide industry to a large extent,therefore an operation of desilication for this type of bauxite,to improve the ratio of A/S,plays a vital role in the process.In this paper the ore sample is taken from Zhaotong in YunNan province,the assay shows that it contains Al₂O₃ 67.13%,SiO₂ 13.08%respectively in the run-of-mine at a ratio of 5.13 of A/S,valuable minerals are diasopre and boehmite in the bauxite,accounting for 47.96%,19.18%respectively,the gangue consists of kaolinite,white mica and quartz with a trace of anatase,goethite.According to features of the run-of-mine,it carries out a series of tests of desilication in this paper,and an optimum operation flowsheet is determined.The test mainly contain tests of desilication by single gravity separation,a combination process of gravity separation and flotation,and a combined flowsheet of gravity separation,classification and flotation respectively,moreover some tests on the usage of backwater.Based on the result of test of single gravity separation,it gives that the run-of-mine is classified firstly by spiral chute,a fraction of coarse particles which has a better liberation can be pre-separated,and qualified concentrate can be produced at a yield of 45%.On the other hand,tailing produced by spiral chute can be deslimed partially through hydraulic cyclone,but underflow from hydraulic cyclone containing 30%Al₂O₃ in yield,must be recovered in the susquent process.As shown in the result of the test of a combination of gravity separation and flotation,the flowsheet contains spiral chute separation with single stage roughing and single stage cleaning,flotation process with single stage roughing,single stage scavenging and four stage cleaning.Middling from each cleaning stage is returned to the previous stage in order.A concentrate with a A/S ratio of 6.41,containing Al₂O₃ 70.73%,SiO₂ 9.54%respectively,can be obtained at a recovery of 68.83% by this flowsheet.In line with the results of a combined flowsheet of gravity separation,classification and flotation,the flowsheet consists of spiral chute separation with single stage roughing and single stage cleaning,hydraulic cyclone classification with two stage classify,flotation process with single stage roughing,single stage scavenging and three stage cleaning.Middling from each cleaning stage is orderly returned to the previous stage.It can get a concentrate with a A/S ratio of 7.34,containing Al₂O₃ 70%-71.56%,SiO₂ 9.75%respectively,at a total recovery of 60%-75%.Results of the two flowsheet for desilication imply that both of them can produce qualified products,have a good performance in desilication.In the paper it has developed a noble effective and economic way of desilication for this type of bauxite,and can give a reference to the desilication procedure by mineral processing.