Recovery Of Vanadium From Steelmaking Slags

Converter slag is the one of three industrial wastes. Utilization ratio of steel slag is only 50% in China, Which is less than that of developed countries. Usually steel slag is used as metallurgical materials, cement, roadbed materials, construction materials and phosphate fertilizer. Converter slags of Pangang contains 1³% of V₂O₅. It is higher than that of vanadium-stone coal (containing about 1% V₂O₅). Valuable vanadium resource will be wasted if the converter slags is disposed directly as ordinary steel slags. It is difficult to reclaim vanadium from the slag because its higher CaO content. Techniques of extracting vanadium from steel slags is very perfect, but it is not fit for containing high CaO and low V₂O₅ slag due to very large consumption of sodium salts and acid. So it is necessary to explore novel technics to recovery vanadium from the steel slags and make use of the other remained ingredients effectivly.This paper mainly investigated distribution of the vanadium-oxide in the as–received V-bearing converter slag and different ingredients, basicity, CaF₂, temperature, time of constant temprature effecting on distribution ratio of vanadium, phosphorus and manganese between ferroalloy and slags. The aim to prove feasibility of extracting vanadium from Panzhihua converter slags by using of carbon thermal reduction process and separating vanadium and phosphous from the obtained V-bearing ferroalloy.The vanadium-oxide in the as–received V-bearing converter slag is distributed both in the lime solid solution and the tricalcium silicate; in the synthetic slag the vanadium-oxide was found mainly in the tricalcium silicate for the slag containing 3.4% V₂O₅, but for the slag containing 6.0% V₂O₅ the vanadium-oxide was found in the form of CaV2O6-Ca2P2O7 solid solution in which the V₂O₅ content is as high as 30%.The slag is mixed with additive and melt at 1873K in a graphite crucible. After keeping 1 hour vanadium distribution ratios is 45 and 15, phosphorus distribution ratios is 26 and 48 between ferroalloy and slags when the slags containing Al2O3 for 22.6%, R=0.91 and the slags containing Al2O3 for 11.6%, R=0.34 respectively. More Al2O3 can enhance vanadium distribution ratio when the slags basicity is about 1. Basicity has an great effect on reducing process. Vanadium recovery rate was highest (91.6%) at R = 1.5, and it decreased to 73.9% at R = 3.0, then increased with the increasing of basicity. The distribution ratios of vanadium, phosphorus and manganese increase gradually with increasing CaF₂ percentage. The distribution ratios is the highest at 3% CaF₂, but it decreased at 4% CaF₂. The distribution ratios increase with temperature and reaction time. XRD analysis confirmed that the main phases of the remained slag after reduction were Ca2SiO4,Ca3SiO5,aluminous calcium silicate and aluminate calcium respectively. It can be used as high quality cement materials or metallurgical fluxes.