National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources

Changsha, China

National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources

Changsha, China
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Zhang W.,Central South University | Li J.,National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources | Zhao Z.,Central South University | Zhao Z.,National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources | And 3 more authors.
Hydrometallurgy | Year: 2015

In this research, W and Mo were separated and recovered from high-molybdenum synthetic scheelite by leaching with HCl solutions containing H2O2 as the chelating agent. The effects of the leaching parameters, such as temperature, leaching time, HCl concentration and H2O2 concentration, on the recovery of W and Mo were investigated. The results show that W and Mo were effectively extracted at room temperature and low acidity. With a leaching temperature of 30 °C, an L:S ratio of 10:1, an HCl concentration of 1.5 mol/L, an H2O2 concentration of 2.5 mol/L and a leaching time of 40 min, the recovery of W and Mo was 97.7% and 99.4%, respectively. Thermal decomposition was then employed to treat the leaching solution. W was transformed into tungstic acid, whereas Mo remained in solution. At 60 °C, 97.47% of W was precipitated, and the separation factor reached 105. © 2015 Published by Elsevier B.V.


Zhang W.,Central South University | Li J.,National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources | Zhao Z.,Central South University | Zhao Z.,National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources
International Journal of Refractory Metals and Hard Materials | Year: 2015

The extraction of tungsten from scheelite concentrate using phosphoric acid as chelating agent in nitric acid solutions was investigated. The effects of the leaching parameters, such as stirring speed, temperature, concentrations of HNO3 and H3PO4 as well as particle size were examined in order to model the kinetics of scheelite dissolution. It was determined that the leaching rate was practically independent of stirring speed and H3PO4 concentration at an investigated range, while increased with increasing temperature and HNO3 concentration. The leaching data agreed quite well with the shrinking core model, with surface chemical reaction as the rate-controlling step. The apparent activation energy was calculated as 52.91 kJ/mol, and the reaction order with respect to HNO3 concentrations was determined to be 0.23. The leaching process using the shrinking sphere model was established as:1-1-x1/3=3.2×102CHNO30.23r0-1exp-52910RT. © 2015 Published by Elsevier Ltd.


Zhao Z.-W.,Central South University | Zhao Z.-W.,National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources | Cao C.-F.,Central South University | Chen X.-Y.,National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2011

In order to develop a low-cost approach for separating macro amounts of Mo and W, the effects of parameters on the separation using FeSO 4 as precipitation reagent were studied. The results show that the optimum reaction temperature is 10°C, and the separation factor does not further improve after a reaction time of 7 h. Moreover, slow dropping speed of the precipitation reagent is beneficial for improving the separation efficiency. When the H +/W molar ratio is below 1/1, the addition of acid to a neutral solution is favorable to the separation. For the solution with an ammonium concentration below 3 mol/L, the separation factor is high due to the high W-precipitation rate. Furthermore, the method is also effective when it is applied to industrial solution containing some other impurities. All these indicate the ferrous salts have great potential for removing W from Mo on a commercial scale. © 2011 The Nonferrous Metals Society of China.


He G.,Central South University | Zhao Z.,Central South University | Zhao Z.,National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metal Resources | Wang X.,Central South University | And 4 more authors.
Hydrometallurgy | Year: 2014

The reaction kinetics for the leaching of scheelite with hydrogen peroxide and hydrochloric acid have been studied to determine the effect of process parameters, such as temperature, concentrations of hydrogen peroxide and hydrochloric acid and particle sizes. The Avrami-Erofeev equation and the Mampel equation were proposed based on the experimental data. Comparing the curve obtained from the kinetic model equation and experimental data, it was determined that both equations were well-fitted to the experimental data. Comparison of the results also demonstrated that Avrami-Erofeev equation was the best kinetic model equation. The Avrami-Erofeev equation was as follows:-ln1-x=5.60×102×CH2 O20.29×e-38930RT×t1.01. © 2014 Elsevier B.V.

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