Research On The Effect Of Roasting Decarburization On The Flotation From Vanadium-bearing Stone Coal And Its Flotation Technology

Vanadium-bearing stone coal is an unique and abundant resource in China,however,due to the properties of vanadium-bearing stone coal are complex,the vanadium grade and occurrence are generally low and multiple,the current technology of vanadium extraction faces the problems in terms of enormous ore handling quantity,high reagent consumption,low vanadium leaching rate,complex purification enrichment and high production cost,so pre-concentration of vanadium in stone coal before leaching is significant to relieve these problems.For raw stone coal,the minerals are severely contaminated by relative high content carbon,the surface differences are small,and flotation effect is poor.In order to solve these problems,based on the process mineralogy of the vanadium-bearing stone coal from Hubei province,research on the effect of roasting decarburization process on flotation and its flotation experiment were carried out,and the main results are as follows:?1?The process mineralogy of raw ore showed that stone coal from Hubei province belongs to typical high-calcium and mica-type vanadium-bearing stone coal,in which the grade of V₂O₅ and CaO are 0.71%and 5.45%,respectively.Besides,88percent of vanadium exsists in the lattice of mica with taking place of Al???as isomorphism in the state of V???and V???.?2?The research of roasting decarburization process and process mineralogy of decarbonized sample showed that reactions that the oxidation of pyrite,combustion of carbon and calcite decomposition occurred successively in the vanadium-bearing stone coal with increasing roasting temperature.The proper condition of roasting decarburization is at 550?for 1.5 h,when the carbon was almost removed without f-CaO generated,and pulp pH and concentration of Ca²⁺didn't increase.Hence,it is beneficial to the subsequent flotation and leaching of mica in acidic conditions.After roasting decarbonization,carbon almost disappeared,the grade of V₂O₅ rose from0.71%to 0.79%,the grade of CaO rose from 5.45%to 5.92%,pyrite was oxidized into hematite,part of calcite decomposed and changed into anhydrite.The average particle size of micro-grained disseminated minerals in decarbonized sample was rather small.The particle size,hardness and shape differences between mica and gangue minerals provide a premise for selective grinding of decarbonized sample.?3?The results of selective grinding of decarbonized sample showed that both ball mill and rod mill exhibited the characteristic of selective grinding due to the relatively big grindability differences between vanadium-bearing mica and gangue minerals?internal factor?.However,in the rod milling products,the size distribution was more uniform and V₂O₅ grade range among size fractious was larger than that of ball milling products.Hence,selective grinding effect of rod mill is superior to that of the ball mill.Both flotation tests and mica liberation analyses showed that the best grinding fineness by rod mill was 84.62%passing 74?m.The results of classification test showed that the optimal separation size was 30?m,when the yield of concentrate1 was 34.69%,V₂O₅ grade was 0.96%,and recovery was 41.68%.It's not necessary to add the dispersant to disperse pulp,and concentration effect of grading flotation is poor,which means it can be directly treated as the vanadium concentration.?4?The technological process of“rod milling-classification-reverse flotation of calcite-direct flotation of mica”was determined through floatation experimental research on decarbonized sample.Concentrate 1 and 2 were combined as the final concentrate,of which the yield was 61.66%,V₂O₅ grade was 1.07%,and recovery was 83.30%.The left was the final tailing,where yield was 38.34%,V₂O₅ grade was0.34%,V₂O₅ loss rate was 16.70%,CaO grade was 7.59%,and CaO discarding rate was 62.52%.?5?Analysis results of flotation product revealed that mica in concentrate 1 and2 was mainly independent distribution,the V₂O₅ grade of final concentrate was not high because mica was generally associated with quartz,hematite and feldspar,and the calcite with low hardness is easy to be ground into fine concentrate 1,which make it difficult to improve vanadium grade and reduce CaO grade of concentrate 1 by flotation.The vanadium loss in tailing 1 and 2 was mainly due to the close association between mica and calcite,feldspar or hematite.