Vanadium Extraction From Stone Coal By Oxidizing Roasting-compound Alkaline Leaching Method

Vanadium, which is a rare metal with high melting poin t, is an important national strategic resource. As a kind of important stone coal vanadium ore resource of China, has huge reserves in many provinces in southern china. Our research and industrial production late vanadium from stone coal, using sodium roasting and water leac hing process of traditional V₂O₅ products, this process produces a large number of Cl₂ and HCl gas in the roasting process, the air pollution is serious, and the total recovery rate of vanadium is generally low. In order to reduce vanadium industrial pollu tion, improve the recovery rate of vanadium and reduce the production cost, this paper adopts composite oxidizing roasting alkali leaching process, carried out a series of research on roasting, leaching and leaching liquid circulation of stone coal.Experimental study on the effect of the amount of NaOH and sodium carbonate ratio on the leaching rate of vanadium in stone coal roasting. Under the optimum leaching agent ratio, the influences of leaching temperature, liquid-solid ratio, time effect of vanadium leaching, and the leaching liquid recycling test research. The results showed that: in the leaching agent relative coal mass of 12% NaOH and 4% soda ash ratio, the leaching rate of vanadium reached 88.67%, as the leaching rate of vanadium leaching agent is about 10% higher than using 12% separate NaOH; under the optimum leaching agent ratio conditions, the optimum conditions were: 1 mol/L, NaOH concentration in leaching solution soda leaching 0.13 mol/L, temperature 95, time 3 h, ratio of liquid to solid 3:1. The role of soda leaching in compound alkali is dissolved: hand Na⁺ and OH^- promote vanadium; on the other hand, in the stone coal containing calcium after roasting generated metavanadate pyrovanadate calcium, calcium, CO₃^2- and HCO3- reacted with soda ash provides more insoluble CaCO₃ promote vanadium leaching. Soda ash can improve the leaching rate of vanadium from stone coal and to a certain extent, reduce the production cost.The leaching solution after solid-liquid separation recycling, adding seco nd times the original leaching agent dosage of 1/4, adding third original leaching agent dosage of 1/2, the average leaching rate reached 83.40%. Leaching agent consumption decreased significantly. The pollution of gas produced in the oxidation roasting le ss, wastewater after treatment can meet the discharge standards, pollution generated in the production process can be effectively controlled.