Pre-enrichment Process And Mechanism Of Vanadium From High Calcium Mica-type Vanadium-bearing Shale By Roasting—flotation Process

Vanadium-bearing shale is an unique and abundant resource in China.It is significant for the development of vanadium industry that extracting vanadium from vanadium-bearing shale in China.Due to the properties of vanadium-bearing shale are complex,the grade are low and the occurrence of vanadium are diversification,the current process 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.In allusion to the above problem,the"roasting decarburization-desliming-flotation"pre-enrichment process was proposed to treat tongshan vanadium-bearing shale from Hubei province.Meanwhile,puremuscovite,quartz and calcitewere used to study the effect of roastingon the flotability and the influence of unavoidable metal ionson the dispersion and agglomeration.According to the study of pure ores,the"roasting decarburization-desliming-flotation"pre-enrichment process was further optimized and the pre-enrichment of vanadium was realized.The main results are as follows:?1?The grade of V₂O₅ in tongshan vanadium-bearing shale from Hubei province is low,only 0.71%.Vanadium mainly occurs in the mica mineral?muscovite,biotite and illite?.The grade of CaO reached 5.45%and the main minerals are quartz,mica mineral,carbon,calcite,feldspar,etc in this shale,so it belongs to typical mica type vanadium-bearing shale with low vanadium and high calcium.?2?The reactions of the oxidation of pyrite,combustion of carbon and calcite decomposition occurred successively in the roasting process of vanadium-bearing shale.Roasting had no effect on the natural flotability of puremuscovite and quartz under 1000?.When roasting temperature over 600?,the small size of muscovite sintered on the surface of the big size muscovite results in the decrease of specific surface of the muscovite samples,thereby reducing the reagent consumption.Calcite will begin to decompose after roasting temperature over 600°C.Calcite decomposition will generate calcium oxide,making the increase of Ca²⁺concentration in the pulp and affecting the flotation recovery of calcite.?3?The dispersion and agglomeration of muscovite and quartz were affected by the crystal structure,pulp pH and the valence and concentration of metal ions.The layer structure of muscovite affects the agglomeration form in acid pulp,the form of“floor?001?-edge"is mainly form was confirmed with DLVO theory calculation.The size of the absolute value of Zeta potential of mineral surface were changed by divalent metal cations calcium,magnesium and trivalent metal cations iron,aluminum compressed double electric layer,when they were in the form of ions,thereby the degree of dispersion and agglomeration of the mineral particles was changed in the pulp;when they were in the formof hydroxy complex or hydroxyl sediment,the degree of dispersion and reunite of the mineral particles was changed through the electrostatic force because of the positive chargeon the surface of hydroxy complex or hydroxyl sediment.?4?Based on thedifferent hardness of minerals in shale,and the special laminar morphology of mica mineral,the selective grinding of rod mill is better than ball mill.In grinding production,vanadium tend to concentrate in coarse?+104?m?and fine?-38?m?fractions.The grade of V2O5in intermediate fraction?-104?m+38?m?is low.The best grinding process is rod mill,grinding concentration C=50%,filling rate?=36.9%,rod ratio m_?16:m_?14:m_?12=2:1:1,grinding fineness-74?m 84.62%.According to the distribution of multi-elements,it is determined that the desliming particle size is not greater than 30?m,and the final mud product should be recovered as concentrate under this grinding fineness.?5?Through the principle process of the"roasting decarburization-desliming-flotation",the decarburization sample can get good indicators,the concentrate yield of 550°C decarburization sample was 61.66%,V₂O₅ grade is 1.07%,V₂O₅ recovery is83.30%;the concentrate yield of 700°C decarburization sample was 53.22%,V2O5grade was 1.06%,recovery was 71.46%.?6?For tongshanvanadium-bearing shalefrom Hubei province,ensuring the recovery of vanadium,pre-enrichment process can effectively enrich the vanadium-bearing mineral,throw away 38%to 47%the tailings,reduce the capacity of leaching process and significantly improve the leaching rate of vanadium.