Extraction Of Vanadium From The Combustionash Of Low Calorific Value Stone Coal In Southern Shaanxi Blending Coal

In our country, stone coal is a unique carbonaceous shale with low carbon, highsulfur and high ash content and associated vanadium, nickel, molybdenum, uraniumand other valuable metals. The traditional stone coal utilization efficiency is low, onlydo the raw materials of vanadium extraction. It is one of the important subjects to studyto improve the level of comprehensive utilization of stone coal resources. Using stonecoal to generate electricity, extracting vanadium from combustion ash andcomprehensive recycling is one of the developing direction of vanadium extractionfrom coal stone in our country.In view of the low calorific value stone coal containing vanadium in southernShaanxi, preparation of ash in the laboratory are adopted to simulate the blendingcombustion method. According to the requirement of fuel heating value of the fluidizedbed combustion to generate electricity, the stone coal and anthracite coal blending ratiowas calculated, the ash resulting from the mixed coal combustion continue to extractvanadium.On the basis of literature review and analyzing basic characteristics of stone coal ash,the exploration test and conditions test were carried out. The “stone coal blendingdecarburization-burning ash acid leaching-(recovery K from leaching liquor)-extraction and re-extraction-vanadium precipitation-calcination and get V2O5products" process was used. Focusing on vanadium leaching, extraction, re-extraction,vanadium precipitation, calcination and potassium recovery, the main technologicalparameters of each process was determined.Stone coal and anthracite coal mixed in a ratio of3:1and burned to obtain stone coal ash. Stone coal ash leached in acid directly in the way of countercurrent washing andcirculating leaching with infusion of0.5%1#leaching agent+4.5%2#leaching agent,dosage of sulfuric acid32.5%, the liquid-solid ratio2:1, leaching temperature85~90℃,leaching time8h, stirring speed was150rpm, the leaching rate of vanadium was78~82%.Aluminium potassium sulfate was recycled by crystallization from leach liquor,aluminum sulfate potassium continue to transition to potassium sulfate.4stagecounter-current extraction with leach liquor after lime neutralization and scrap ironreduction. Extraction solvent composed of12.5%P204+5%TBP+85%sulfonatedkerosene, phase ratio (O/A)=2:1, extraction concentrate pH=2, oscillating period was2min and let it sit for1min, vanadium extraction rate is99.31%. Use4stagecountercurrent re-extraction, re-extraction agent is1.5mol/L sulfuric acid, phase ratio(O/A)=4:1, oscillating period was4min, and let it sit for1min, re-extraction rate ofvanadium was96.94%.After adding sodium chlorate to the re-extraction solution to oxidize vanadium,precipitating vanadium and calcining were carried out. Vanadium precipitationrecovery>97%, red vanadium pyrolysis recovery>99%, the total vanadium recoveryis71.69%~71.69%. The V2O5content of pure vanadium product at98.13%witchmeet the national standards of GB3283-87V2O598. Content of KAl(SO4)2·12H2O inaluminium potassium sulfate product is greater than99%and grade of K2O inpotassium sulfate product is43.45%, witch consistent with national standards.This study using the ash obtained from the burning low calorific value stone coalblending coal to extract vanadium, the utilization rate of coal resources can improvesignificantly. The process of extracting vanadium studied in this paper easy to realizecontinuous operation with less "three wastes" emissions and high vanadium recovery.Research results provides an important theoretical approach for the comprehensiveutilization of combustion ash result from low heat value stone coal in southern Shaanxiblending stone, which laid a foundation for further to carry out the relevant industrialtest. It has significant reference and application value for the efficient use of lowcalorific value stone coal in southern Shaanxi province.