Bioleaching of vanadium from stone coal vanadium ore by Bacillus mucilaginosus:Influencing factors and mechanism

Vanadium and its derivatives are used in various industries,including steel,metallurgy,pharmaceuticals,and aerospace engineering.Although China has massive reserves of stone coal resources,these resources have low grades.Therefore,the effective extraction and recovery of metallic vanadium from stone coal is an important way to realize the efficient resource utilization of stone coal vanadium ore.Herein,Bacillus mucilaginosus was selected as the leaching strain.The vanadium leaching rate reached 35.5%after 20 d of bioleaching under optimal operating conditions.The cumulative vanadium leaching rate in the contact group reached 35.5%,which was higher than that in the noncontact group(9.3%).The metabolites of B.mucilaginosus,such as oxalic,tartaric,citric,and malic acids,dominated in bioleaching,accounting for 73.8%of the vanadium leaching rate.Interestingly,during leaching,the presence of stone coal stimulated the expression of carbonic anhydrase in bacterial cells,and enzyme activity increased by 1.335-1.905 U.Enzyme activity positively promoted the production of metabolite organic acids,and total organic acid content increased by 39.31 mg·L^(-1),resulting in a reduction of 2.51 in the pH of the leaching system with stone coal.This effect favored the leaching of vanadium from stone coal.Atomic force microscopy illustrated that bacterial leaching exacerbated corrosion on the surface of stone coal beyond 10 nm.Our study provides a clear and promising strategy for exploring the bioleaching mechanism from the perspective of microbial enzyme activity and metabolites.

Water quality,natural chemical weathering and ecological risk assessment of the contaminated area of vanadium ore in Yinhua River,China:Evidence from major ions and trace elements

There are abundant vanadium ores in the Cambrian strata in southern Shaanxi,China.Many years of mining activities and surface leaching have polluted the surface water to a certain extent,but the researches on the water quality characteristics and pollution degree are relatively weak.This contribution was organized to investigate the surface water quality by general parameters,including TDS,Eh,pH,DO,TOC,COD,and EC,in the vanadium ore belt(Yinhua River basin).Major ions were determined to detect the water type and natural chemical weathering,while trace elements were used to illustrate their geochemical characteristics and ecological risk assessment of heavy metals.The study found that the surface water was weakly alkaline and mainly dominated from normal to pool grade.The particle size with1000–10,000 nm of suspended particles was the main carrier of organic matter.The concentration of HCO_(3)^(-)and SO_(4)^(2-)in the anions and Ca^(2+)and Mg^(2+)ions in the cations were relatively high,and the water type was Ca-Mg-HCO_(3)-SO_(4) type.Rock weathering had a great influence on surface water,and the weathering products were mainly silicate and carbonate.Compared with the Type river,the contents of V elements showed an obvious positive anomaly,which may be affected by mining activities of vanadium ore and the annual leaching of the tailings pond.As and Cd in the surface water was polluted seriously.The integrated pollution index suggested that the surface water pollution was serious,and the main stream was more serious with the increasing tailings ponds.

Infiltration behavior of sintering liquid on nuclei ores during low-titanium ore sintering process

Sinter strength is dependent not only on the self-intensity of the residual rude and bonding phase but also on the bonding degree between them. The infiltration behavior of sintering liquid on nuclei ores influences the bonding degree, which ultimately determines the sinter strength. Infiltration tests were conducted using micro-sinter equipment. The infiltration area index of original liquid（IAO）, infiltration volume index of secondary liquid（IVS）, and sinter body bonding strength（SBS） were proposed to study the melt infiltration behavior. The results show that the IVS first increases and then decreases with increasing TiO2 content in adhering fines, whereas the IAO exhibits the opposite behavior. Compared with the original liquid, the secondary liquid shows lower porosity, smaller pores, and more uniform distribution. The SBS increases first and then decreases with increasing IAO and TiO2 content, and reaches a maximum when the IAO and TiO2 contents are approximately 0.5 and 2.0wt%, respectively. The SBS first increases and then tends to be stable with increasing IVS. The TiO2 content is suggested to be controlled to approximately 2.0wt% in low-titanium ore sintering.