Selective Flotation of Scheelite and Calcite
01 Mar 1985-
TL;DR: In this paper, an attempt to improve the selectivity of separ-ation of scheelite, based on the flotation of pure clacite-scheelite system using sodium oleate as collector, is presented.
Abstract: The gold tailings from Gold Fields containing low scheelite values has a compled mineralogy with hornblende, quartz, arsenopyrite and calcite as major gangue minerals. The most difficult problem in scheelite flotation is not the removal of the siliceous or sulphide gangue, but the separation of Scheelite and calcite minerals which have similar surface properties. This is greatly influenced by many factors(1)such as (1) the extent of adsorption of the collectors (2) the dissolution of the minerals and the interference by the released species and (3) the intera-ction of adsorbed ions with the mineral surface. Direct
flotation tests to recover scheelite from tailings failed due to the dilution of the concentrate by calcite. Hence to adopt the flotation process successfully, it is nece-ssary to depress the calcite selectively which is not achi-eved easily(2) due to the presence of small amounts of Ca, Mg and Fe salts and the lean grade of the ores to be
treated. Slime coating(3) is also another factor adver-sely affecting the flotation of scheelite. The present study is an attempt to improve the selectivity of separ-ation of scheelite, based on the flotation of pure clacite-scheelite system using sodium oleate as collector.
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TL;DR: Froth flotation of scheelite has regained new focus since the 2010s and research regarding floatability and reagents has made great progress over the years as discussed by the authors. But due to similar properties, most attempts have limited success or only specific application (linked to a type of ore or a location).
Abstract: Froth flotation of scheelite has regained new focus since the 2010s and research regarding floatability and reagents has made great progress over the years. The main objective was and remains the selective flotation of scheelite from other calcium-bearing minerals, in particular calcite, fluorite and apatite. Due to similar properties, most attempts have limited success or only specific application (linked to a type of ore or a location). This article aims at reviewing all general physical-chemical information on froth flotation of scheelite, including electrokinetic properties, influence of pH and already existing reagents as well as ones still under examination. It appears that chelating or mixed collectors and modified versions of sodium silicate and quebracho hold great promise for scheelite flotation, while the use of said depressants and/or promoters seems inevitable.
145 citations
TL;DR: In this paper, the effect of adding metallic cations [FeSO4, Al(NO3)3, and Zn(SO4)] prior to sodium silicate was investigated.
50 citations
TL;DR: This study investigates an environmentally friendly technology that utilizes waste by-products (waste acid and waste alkali liquids) to treat mineral processing wastewater and finds that the efficient removal of silicate is confirmed by industrial testing at a plant.
46 citations
Cites background from "Selective Flotation of Scheelite an..."
...It plays an important role in 21 the flotation of scheelite (Gao et al. 2016, Wang et al. 2016, Han et al. 2017), fluorite 3 1 (CaF2) (Gao et al. 2015), phosphate (Dho and Iwasaki 1990) and xenotime (YPO4) 2 (Zhang and Anderson 2017)....
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TL;DR: The greenest, most efficient, and cheapest method for scheelite flotation is to use fatty acids as collectors with sodium silicate as depressant, although this solution suffers from a crucial lack of selectivity regarding the above-mentioned calcium salts.
Abstract: Recently, tungsten has drawn worldwide attention considering its high supply risk and economic importance in the modern society. Skarns represent one of the most important types of tungsten deposits in terms of reserves. They contain fine-grained scheelite (CaWO4) associated with complex gangue minerals, i.e., minerals that display similar properties, particularly surface properties, compared to scheelite. Consistently, the froth flotation of scheelite still remains, in the twenty first century, a strong scientific, industrial, and technical challenge. Various reagents suitable for scheelite flotation (collectors and depressants, mostly) are reviewed in the present work, with a strong focus on the separation of scheelite from calcium salts, namely, fluorite, apatite, and calcite, which generally represent significant amounts in tungsten skarns. Albeit some reagents allow increasing significantly the selectivity regarding a mineral, most reagents fail in providing a good global selectivity in favor of scheelite. Overall, the greenest, most efficient, and cheapest method for scheelite flotation is to use fatty acids as collectors with sodium silicate as depressant, although this solution suffers from a crucial lack of selectivity regarding the above-mentioned calcium salts. Therefore, the use of reagent combinations, commonly displaying synergistic effects, is highly recommended to achieve a selective flotation of scheelite from the calcium salts as well as from calcium silicates.
34 citations
Cites background from "Selective Flotation of Scheelite an..."
...In particular, Patil and Nayak (1985) efficiently depressed calcite using a hydrosol composed of Na2SiO3 and ferrous sulfate with no negative impact on scheelite (Patil and Nayak, 1985)....
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...in the flotation process allows to modulate the selectivity of the separation (Abeidu, 1973; Mercade, 1975; Hanna and Somasundaran, 1976; Detienne, 1978; Patil and Nayak, 1985; Oliveira and Sampaio, 1988; Schubert et al., 1990; Raatz, 1992; Feng et al., 2017) (see Figure 12)....
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TL;DR: In this article, the effect of acidified water glass is evaluated through Mineral Liberation Analysis (MLA), froth analysis, Raman and Nuclear Magnetic Resonance (NMR) spectroscopy in order to hypothesize its mechanism.
Abstract: Sodium silicate is one of the main depressants against calcite and fluorite in the scheelite flotation industry. In the first part of this article, the authors acidified sodium silicate (AWG) with three acids (sulfuric, oxalic and hydrochloric) to improve its performance. Results showed that acidified water glass outperforms alkaline water glass in terms of selectivity: it increases mainly the grade by further depressing silicates and calcium-bearing minerals. In most cases, AWG requires lower dosages to do so. The effect of acidified water glass is evaluated through Mineral Liberation Analysis (MLA), froth analysis, Raman and Nuclear Magnetic Resonance (NMR) spectroscopy in order to hypothesize its mechanism. MLA shows that AWG affects silicates and sulfides more intensely than semi-soluble salttype minerals. Froth observations indicate other species in solution associated to the acid having an impact on the flotation results. Raman spectroscopy and NMR measurements indicate that the solution undergoes deep depolymerization when water glass is acidified. Lower molecular weight silica species, specifically Si-O monomers such as SiO(OH)3will be responsible for the depression of the gangue minerals and are the drivers of the selectivity of AWG, more than orthosilicic acid. Depolymerization is more or less effective depending on the mass ratio of the acid to water glass and depending on the acid.
6 citations
Cites background from "Selective Flotation of Scheelite an..."
...Several studies involve mixing sodium silicate with Fe(II) or Al sulfates to improve flotation (Deng et al., 2018; Foucaud et al., 2019a; Patil and Nayak, 1985; Tian et al., 2019)....
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References
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TL;DR: The electrophoretic mobility of scheelite (CaWO4) from King Island, Australia, has been measured in a variety of inorganic electrolytes, mostly at constant ionic strength and controlled pH.
33 citations
TL;DR: In this article, the role of chemical species in the calcite-apatite system was examined by conducting flotation of each mineral in various supernatants prepared by mixing with water, and the results were analyzed in terms of the surfactant's solubility properties and the mineral's electrochemical and dissolution properties.
Abstract: A knowledge of the role of effects and interactions of chemical species is important in developing an understanding of the behavior of mixed minerals and natural ores in beneficiation processes such as flotation and flocculation. In this study the role of such species was examined for the calcite-apatite system by conducting flotation of each mineral in various supernatants prepared by mixing with water. Supernatants of apatite and even that of calcite depressed the flotation of calcite markedly in the pH range of 5 to 13. Addition of Ca(NO3)2, K2CO3, and K3PO4 also produced definite effects under various pH conditions. Apatite flotation was also affected by the mineral supernatants and by carbonate and phosphate solutions. The results are analyzed in terms of the surfactant’s solubility properties and the mineral’s electrochemical and dissolution properties. While depression of calcite flotation by the dissolved species is found to be governed by depletion of oleate by bulk precipitation, the depression of apatite flotation is caused by the carbonate and phosphate species in the system. Turbidity measurements and a thermodynamic analysis of possible interactions in the system support these considerations. The effect of the supernatant of minerals on their own flotation suggests the important role of kinetics of various surface interactions in comparison to that of mineral dissolution.
31 citations