| At present,vanadium oxide production technology requires that calcium content of vanadium slag is less than 2.5%,it is not possible to add calcium oxide for dephosphorization in the process of vanadium extraction by converter blowing from vanadium-bearing hot metal.It is not conducive to the production of clean steel with high added value,which affects the comprehensive economic benefit of vanadium extraction steelmaking.In order to reduce the adverse effect of converter vanadium extraction process on steelmaking,this paper puts forward the idea of adding a proper amount of calcium oxide to pre-dephosphorization during vanadium recovery process in converters,but no method to make use of high calcium and high phosphorus vanadium slag,the application of phosphorus removal and vanadium extraction from vanadium-containing hot metal technology is restricted.In order to solve the problem of the utilization of high calcium and high phosphorus vanadium slag,this paper presents the method of "calcium roasting,acid leaching,solution phosphorus removal and vanadium precipitation".Analysis of high calcium and high phosphorus vanadium slag material composition and distribution of the major elements,focused on reducing calcification roasting temperature and method of acid vanadium solution dephosphorization,the technology of high calcium and high phosphorus vanadium slag to prepare vanadium oxide has been formed.The following important conclusions are obtained:(1)The phase state of high calcium and high phosphorus vanadium slag was found out.High calcium and high phosphorus vanadium slag is mainly composed of vanadium-iron spinel and fayalite,diopside,calcium silicate phase composition,also containing a small amount of apatite and iron oxide.Among them,the vanadium element is mainly found in the spinel,and the calcium is mainly found in calcium silicate,diopside and olivine.Vanadium spinel particle size is about 45 microns of 80%,which Is larger than ordinary.(2)The reaction behavior and mechanism of roasting vanadium slag were studied,found that oxygen enriched roasting can effectively reduce the temperature of calcified roasting,the optimized process parameters were obtained.The conversion rate of vanadium is 89%～90%under the conditions of calcination temperature of about 870℃and the inlet oxygen content is about 13%～15%(When oxygen is not enriched,the oxygen content of industrial rotary kiln is generally 8%～10%).Roasted material is mainly composed of calcium vanadate,iron oxide,pseudobrookite and silicate phases,also containing a small amount of quartz.The best acid leaching process parameters of roasted material are that the size of the clinker is-0.096mm,the acid leaching of pH is 2.7～3.0,the acid leaching temperature is from 50 to 60℃ and the acid leaching time is from 50min to 60min,under this condition,the conversion rate of vanadium is 89%～90%.(3)A new method for deeply removing phosphorus with zirconium sulfate is presented and established.Found that the ideal effect can be obtained by using zirconium salt and iron salt to remove phosphorus from acid vanadium solution,but the loss of vanadium is greater by using iron salt.The phosphorus removal rate is about 91.33%,and the yield of vanadium is about 99.57%by zirconium sulfate,while the long storage time and the concentration of vanadium is not good for phosphorus removal.Main phases of phosphorus removal are Zr(HPO4)2,ZrSiO4 and Ca3Si2O7.(4)The effect of various parameters on the precipitation of acid ammonium salt after removal of phosphorus was studied systematically,the optimized process parameters and qualified products were obtained.Solution after phosphorus removal under the condition of pH=1.9～2.1 and ammonium adding coefficient 1～1.2,the vanadium precipitation rate was more than 99%,the quality of obtained V2O5 conformed to the national standard requirements(《YB/T 5304-2011》). |
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