Process mineralogy applied to exploration, development and exploitation of select Tungsten Ores

Abstract

Applications of process mineralogy to the exploitation of tungsten ores range diversely from early exploration leading to the development of mineralized targets through a variety of metallurgical test work and pilot plants studies, to the troubleshooting of mine and plant production. These are described with amphasis on select U.S. scheelite deposits and have included the following: 1. (1) Quantitative evaluation of tactite mineralogy by X-ray diffraction to establish to establish the relative favorability of various tactites of diverse mineralogic composition. 2. (2) A rapid XRD method is described for the determination of end-member garnet compositions of the andradite-grossularite series, pertinent to the favorability assessment of tactite composition for tungsten mineralization. 3. (3) Identification and textural examination of tungsten-bearing minerals and potential by-products in gangue matrices. 4. (4) Extraction and precipitation of tungsten as synthetic scheelite and ammonium paratungstate, 5 (NH 4) 2O.12WO 3.7H 2O. 5. (5) Differential thermal analysis of ammonium paratungstate in oxidizing, reducing and neutral atmospheres, as a guide to phase transformations intermediate to the production of “blue oxide” reduced tungsten oxides and tungsten metal. Stability ranges for the various intermediate tungstates, oxides and carbides of tungsten have been determined and compared for various atmospheres, as a guide to production methods.