| Tungsten, as an advantageous mineral resource of China, is known to all as "monosodium glutamate of industry" and has been widely used in the fields of material, national defense, aviation and shipmaking, etc. With the increasingly depletion of Wolframite resources in southern Gannan Area of China and other areas, the proportion of Scheelite to the total tungsten production has exceeded that of Wolframite; therefore, the reasonable utilization of the valuable Scheelite resource has become significantly important.The material used for the present investigation was obtained from a medium-scale Scheelite ore deposit in Nujiang of Yunnan province. The material is 1.14% WO3 grade. The mineralogy analysis shows that it is quartz-type and Scheelite is the dominant mineral accounting for 91.23% of the total tungsten minerals. The material has an uneven size distribution, with most tungsten minerals disseminated in the narrow range of 0.01-0.20 mm. Therefore, a gravity separation-magnetic separation flowsheet was tested on the ore, on the basis of the mineralogy analysis, and its tailings was further separated with the flowsheet. The feasibility of this flowsheet for the ore was investigated using full-scale tests. The main contents of this study are listed below:1. Grinding tests. Ball grinding and rod grading of the ore and their effects on shaking table separating results were fully examined. It was found that the rod grinding achieves a higher quality concentrate for the optimum grinding fineness and the rod grinding produces much less ultra-fine particles.2. Gravity separations. The ground material was divided into three fractions of +0.074 mm,-0.074+0.038 mm and -0.038 mm and they were respectively tested on jigs, spirals and shaking tables; the results indicate that the shaking table achieves a relatively higher quality Scheelite concentrate and thus these three fractions are all roughed using shaking tables. As the middle products from shaking tables roughing has still a high WO3 grade, these products are further scraped on the tables. The gravity flowsheet produces a final Scheelite concentrate assaying 62.27% WO3 with 69.18% recovery.3. Iron removal with magnetic separation. The rough Scheelite concentrate from gravity separations are tested with magnetic separator to remove iron particles. Under the optimum operating conditions of the magnetic separator, i.e., magnetic intensity of 240 mT and feed% solids of 35%, a final Scheelite concentrate assaying 64.16% WO3 with 69.16% recovery was achieved after the removal of iron particles. 4. Gravity separation-magnetic separation tests of tailings from the Scheelite ore. A Scheelite concentrate assaying 16.97% WO3 with 2.42% recovery was produced with flotation methods; therefore, this tailings can not be effectively treated with conventional flotations. Due to the shortage of research finance and the limitation of time, further flotation studies of the tailings was not performed.5. Full-scale test. On the basis of the pilot-scale investigations as listed above, a full-scale test was carried out on the ore. The test produced a final Scheelite concentrate assaying 65.07% WO3 with 68.17% recovery, which fully validated the pilot-scale tests.In summary, based on the mineralogy analysis of the Scheelite ore a gravity separation-magnetic separation flowsheet was used in the study and a relatively higher performance was achieved. |
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