Aluminous Minerals for Caustic Processing of Scheelite Concentrate
- PDF / 563,123 Bytes
- 7 Pages / 593.972 x 792 pts Page_size
- 59 Downloads / 153 Views
INTRODUCTION
TUNGSTEN (W) has been widely applied to several industrial fields because of its prominent properties such as excellent heat resistance and hardness. Of the two main W resources, wolframite ([Fe, Mn]WO4) and scheelite (CaWO4), attention has been paid to scheelite due to the overconsumption of wolframite until now. The traditional metallurgical processes for extracting W from scheelite mainly include hydrochloric acid leaching,[1,2] soda autoclaving,[3,4] and soda roasting.[5] Caustic soda (NaOH) was proved to be effective in decomposing scheelite with mechanochemical activation.[6] The use of sodium hydroxide to decompose scheelite[7–9] allowed a relatively lower operation temperature than that by soda autoclaving and roasting. The process was successfully used for industrial application. The uses of a large dosage of NaOH and high solid–liquid ratio were also important in raising W recovery. Another measurement as reactive extrusion was used to treat the samples with high solid–liquid ratio. Therefore, it is promising to develop an alternative process using less NaOH under an easy operation. In recent years, the domains of mechanochemistry have drawn much attention and there has been increasing research on them.[10–14] Especially, mechanochemical solid-state reaction shows an excellent potential in synthesizing and decomposing materials, with no extra thermal treatments needed and few impurities MIN CHEN, ZHAO LI, XUEWEI LI, JUN QU, and QIWU ZHANG are with the School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, Hubei, P.R. China. Contact email: [email protected] Manuscript submitted July 11, 2016. Article published online March 27, 2017. 1908—VOLUME 48B, JUNE 2017
formed.[11,15–18] Several examples of mechanochemical reactions between solid NaOH and sulfate or carbonate minerals at a stoichiometric dosage have been reported in our previous publications.[19,20] On these bases, extracting W through a caustic processing of scheelite mechanochemically has been investigated,[21] where Al(OH)3 was further added to react with Ca(OH)2 resulting from the decomposition reaction of scheelite with NaOH to prevent calcium dissolution and, therefore, maintain the high extraction of soluble tungstate. With the successful calcium immobilization using Al(OH)3 as an additive for the caustic processing of scheelite concentrate, and for further investigation for industrial application, this work was aimed at seeking possible alternatives for Al(OH)3 reagent, of which three kinds of aluminous minerals with different alumina compositions and water percentages were compared. The optimized conditions for high W recovery with each mineral were cleared so that the proposal for the extraction process became possible depending on which type of aluminous mineral was available.
II.
EXPERIMENTAL PROCEDURE
A. Samples The scheelite concentrate used in the present study was provided by the Guangdong Institute of Mineral and Geology (China) in the form of powder with an average particle
Data Loading...
