| High calcium-magnesium mica-type vanadium containing stone coal accounts for over 30% of the total vanadium containing stone coal in our country,containing CaO+MgO above 15% of stone coal.Because of high calcium-magnesium material content in ore,using traditional process to extract vanadium,greatly increase the acid and alkali consumption in leaching process and production cost.In addition high acid consumption can lead to serious environmental pollution.Developing green and efficient extracting vanadium process is the urgent problem to solve effective utilization of high calciummagnesium mica-type vanadium containing resources.This study at the support of “National ‘Twelfth Five-Year' Plan Project for Science &Technology Support”,investigated the high calcium-magesium mica-type vanadium containing stone coal from Hubei province based on intergrowth process of “flotation+acid leaching”,and carried out research surrounding the mechanism of flotation concentrate acid leaching process research.The main conclusions are as follows:1.(Containing vanadium)Acid leaching process of mica mineralLeaching test of mica showed that increasing sulfuric acid concentration,leaching time and temperature could improve the leaching rate of Al,K and Si.However,ability to damage the crystal structure of mica was limited by sulfuric acid and leaching rate of Al,K and Si were at lower level.Adding F-containing leaching agent could signally promote the dissolution of Al,K and Si of mica.The crystals structure variation of mica in hydrofluoric acid leaching processes were investigated with Infra-red spectroscopy(FTIR),X-ray diffraction(XRD),and scanning electron microscopy(SEM),the results showed that hydrofluoric acid leaching deformed structure of mica,then adjusting and deforming octahedral and tetrahedron,thus transforming the chemical environment of Al,K,Si and strengthening dissolution abilities in acid.In vanadium containing stone coal,vanadium mainly occurred in the mineral lattice of mica,known as the vanadium containing mica.The leaching behavior of mica indirectlyrevealed the leaching behavior of vanadium containing mica.F-containing leaching agent could promote the leaching of vanadium containing mica.2.Leaching test of mica-type stone coal flotation concentrateHigh calcium-magnesium mica-type vanadium containing concentrate of stone coal after flotation,vanadium exists in mica,tourmaline and iron mineral,and tourmaline minerals vanadium containing accounts for about 10%,belongs to the refractory ore.Increasing the concentration of sulfuric acid,raising the temperature,extending the leaching time and enlarging the liquid-solid ratio were beneficial to the leaching r of vanadium by directly sulfuric acid leaching,but the leaching rate was low.The leaching rate of vanadium could be improved by adding F-containing leaching agent effectively and increased with the increase of dosage of F-containing leaching agent.Under the leaching condition of sulfuric acid concentration of 30%,and dosage of sodium fluosilicate of 16%,liquid-solid ratio of 4:1,leaching temperature of 90 ?,leaching time of 12 h,stirring speed of 600r/min,under the optimum condition,a high leaching rate of86.18% coued be obtained.In addition,under the existence of sodium fluosilicate,adding the oxidant such as nitric acid and potassium chlorate,the former is better,which reached larger vanadium leaching rate,raised by 7%.3.Mechanism for acid leaching of mica-type vanadium containing stone coal flotation concentrateThe XRD and SEM analysis of stone coal flotation concentrate after leaching showed that sulfuric acid leaching mainly reacted on the dissolution of carbonate,chlorite and mica,and caused a lesser damage to major structure stone coal.Under the existence of F-containing leaching agent,crystal structure of vanadium containing mineral were destroyed and surrounded a large number of bonding particles.Then vanadium in crystal lattice packaged at layered structure collapse was released.Insoluble low valence,state of vanadium could quantitatively turn to soluble high valence state to some extent by using oxidant,so as to improve the leaching rate of vanadium from stone coal. |
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