Solvent Extraction Of Tungsten And Molybdenum From Chemical Beneficiation Acid Leach Solution Of Scheelite Middling With High Content Of Molybdenum

Luanchuan molybdenite is a famous large molybdenum ore in the world. The scheelite middling can be obtained by beneficiation process, which normally contains 15%-20% of WO3,>3% of Mo and>10% of P. After chemical beneficiation method using acid, the scheelite concentrate with grade more than 63% of WO3 can be obtained, while large amount of acid leach solution containing high concentrations of tungsten, molybdenum and phosphorus produced. Direct discharge of the solution not only loss metal values, but also seriously pollute the environment. This paper investigates the recovery of molybdenum and tungsten from the acid leach solution using solvent extraction.The study is mainly focused on extraction of tungsten and molybdenum from the solution using several extractants and stripping of loaded organic solutions. The results revealed that the organic system consists of N235+TBP+sulfonated kerosene performed best.The effects of concentration of N235 and TBP, O/A ratio, time, temperature and pH on the extraction of two metals were investigated. The saturated loading capacity(Mo+WO3) of organic system including 15% N235+10% TBP+sulfonated kerosene reached 90.7 g/L using fixed phase ratio method.5-stage counter current extraction of tungsten and molybdenum was carried out. The results showed that the extraction of molybdenum and tungsten reached 99.8% and 98.6% with O/A ratio of 1:2 at 35℃.The loaded organic was firstly eluted using dilute HC1 solution of pH 2 to remove iron, phosphorus and other impurities for four times before stripping of tungsten and molybdenum. The stripping results using two stripping reagents of NaOH and NH3·H2O showed that the solution of NaOH performed better. The effects of NaOH concentration, O/A ratio, time and temperature on the stripping of two metals were investigated. The results showed that the removals of iron and phosphorus reached 99.6% and 77%, respectively, and the stripping of tungsten and molybdenum reached 75% and 91.8% using 2 mol/L NaOH solution with O/A ratio of 3 at 35℃for 10 mins. In addition, the effects of concentration of N235 and octanol, O/A ratio, time, temperature and pH on the extraction of two metals using organic system of N235+octanol+sulfonated kerosene were investigated. The saturated loading capacity(Mo+WO3) of organic system including 20% N235 + 5% octanol + sulfonated kerosene reached 81.3 g/L using fixed phase ratio method.5-stage counter current extraction of tungsten and molybdenum was carried out. The results showed that the extraction of molybdenum and tungsten reached 99.0%and 99.4%with an O/A ratio of 1:1.5 at 35℃.This process is short time consuming, high recoveries of tungsten and molybdenum, recycling of the organic solution, low consumption of reagents, which is expected to be applied in the industry since it's costy and environment-friendly.