The Study Of Dephosphorization From High Phosphorus Hematite By Using Acid Leaching And Utilization Of Leaching Solution

With modern industry's developing rapidly in our country, steel yield of our country has exceeded more than 400 million tons in 2006, become the first one in the world, and it predicted to reach to 480 million tons in 2007. But the iron ore resources of our country is inadequate, in 2006 the amount of imported iron ore reached to 326 million tons which has already occupied more than a half of our country's steel and iron plants needed. Our country has already exceeded Japan and become the biggest country in importing iron ore in the world. With the increasing iron ore importing dependence, our country lost the word's power of international mineral price; it has become a big potential problem of our steel industrial economy. So we must try our best to improve our technique to explore present iron mine resources. In our country there is 7.45 billion tons high phosphorus hematite, about 14.86 percent of total iron resource, but the granule of value mineral is tiny that it is hard for dephosphorization to make it fit for smelting by traditional method. So we need to study new techniques which can dephosphorus containing in hematite, it has tremendous theoretical and practical significance to insure raw material supplying for the steel industrial.The subject select magnetic separation iron concentrates of Hubei Chaoyang Mining Ltd. Changling Mineral Process Plant as a research object. First respectively used hydrochloric acid, sulfuric acid and nitric acid to acid leaching test, ascertained the effect of different acid types on dephosphorization. The iron concentrate has the best effect on dephosphorization by using nitric acid, the effect of hydrochloric acid is inferior to nitrate, and both of their dephosphorization rate can excess 80% in suitable conditions. The effect of sulfuric acid is the worst, its dephosphorization rate only reach 70%, so finally choosed hydrochloric acid as the most applicable reagent. Then progressed acid leaching conditions optimization experiments of hydrochloric acid. The iron concentrate's best conditions of acid leaching dephosphorization are 42 kg/t hydrochloric acid dosage, 35% pulp concentration, 86.03% of -0.074mm iron concentrate granularity, 3 hours reaction time, 200 r/min mixing rate, the dephosphorization rate can be achieved 85.72% in best condition. Then used the waste water which after the acid leaching to recycle hydrochloric acid, investigated the distillation temperature and time affecting on the recycle rate of hydrochloric acid, educing the best conditions of hydrochloric acid recycle are the temperature of 70℃, distillation time of 25 minutes, the recycle rate of hydrochloric acid can be achieved 80.08% in best condition. The residual phosphorus in the waste water after hydrochloric acid recycle, was respectively used AlCl₃, FeCl₃ and Ca(OH)₂ to select reagent test. In waste water the rate of dephosphorization can reach more than 95% by AlCl₃, which can reach more than 85% by FeCl₃, the rate of dephosphorization can reach more than 92% by Ca(OH)₂. The dephosphorization effect of AlCl₃ and FeCl₃ can increase by combining with PAM, but the effect of AlCl₃ combining with PAM becomes gradually lower by dosage increasing, FeCl₃ doesn't have the same trend, and the effect of Ca(OH)₂ is not improved by adding PAM. So finally choosed Ca(OH)₂ as the most phosphorus recycle reagent by considering the cost, and concluded the best phosphorus recycle conditions by using Ca(OH)₂ are pH 9.0, mixing time 15 min, sedimentation time 15 min. Finally, we respectively reused the recycled hydrochloric acid and the residual waste water to add in foregoing acid leaching experiment. There is less effect by reusing them, so they can be recycled to carry out acid leaching waste solution comprehensive utilization.