Research On Extracting Tungsten From Caustic Soda Leach Liquor Of Tungsten Ores To Produce Pure Ammonium Tungstate Solution

Tungsten mineral raw materials which deal with caustic soda is a general technology all over the country, the solvent extraction of tungsten from caustic soda leach liquor of tungsten ores without pH modification to produce ammonium tunstate solution has obvious advantages. To solve the crucial problems which impede the industry application of the new process, carbonate quaternary ammonium salt was used in this systematically investigates. The problems of slow phase separation and low concentration of WO3in strip liquor were successfully solved, while the method to recover the dissolved extraction agent by ion exchange is explored and put forward. The results of this paper provide a reliable basis for the industry application of the process.Basic properties of extraction, scrubbing, stripping have been studied in the funnel, in which organic phase composition has been appropriate selected and the effect of various factors in extraction, scrubbing, stripping have been investigated too. Extraction isotherm were plotted with saturation concentration method at different concentration of NaOH in leach liquor, and with the variation of phase ratio method, the strip isotherm were also plotted, the operating conditions for each stage have been optimized. The results showed that the organic phase comprises50%TOMAC+20%DL-2-Octanol+30%sulfonated kerosene have good properties of phase separation and tungsten extraction,both the extraction rate of tungsten and the loading capacity (for WO3) of organic slightly decreased with the increase of the concentration of NaOH in feed. However, the loading capacity (for WO3) of organic can reach88.3g/L, it still can meet the requirements of deeply extracting tungsten from caustic soda leach liquor of tungsten ores. The addition of NH3-H2O into NH4HCO3as the mixed stripping reagent can improve the stability of strip agent and stripping liquor, best composition of strip agent is3.0mol/LNH4HCO3+1.0mol/L NH3-H2O.The centrifugal extractor was used in the counter current extraction, the experiment showed that centrifugal extractor could solve the problems about slow phase separation of extraction and stripping. In the extraction process, free alkaline in the leaching solution can be used efficiently to the regenerate organic phase, which could eliminate the need for a separate regeneration process. By8stages extraction and12stages strip, the concentration of WO3in strip liquor could reach170g/L and the removing rates of impurity as P could reach90.88%.This paper also has investigated the dissolution loss of organic phase in the process of extraction, washing, stripping and regeneration, the results show that organic phase could cause a much higher loss in the washing, one of the biggest losses in organic phase extraction agent is quaternary ammonium salt. Using ion-exchange to recover the organic phase,the experiment showed that, the loaded resin can be desorbed by NaCl under the ultrasonic affection, COD removal could reach as high as94%, the dissolved extracting agent can be recovered effectively. Furthermore, the stability of the resin is basically stable after ultrasonic affection.On the basis of these study result, as the core of the solvent extraction of tungsten in alkaline without pH modification, a new clean production technology for tungsten hydrometallurgy was presented. Compared with the current ion-exchange and solvent extraction in acid medium, the new process has obvious superiority for its lower consumption of water and wastewater discharge, at the same time, the procedure can be shortened, the consumption of chemical reagent is greatly reduced. Undoubtedly, this clean production process is a prospects for industrial application of tungsten hydrometallurgy for the strong proponent of sustainable development.