Modern hydrometallurgical production methods for tungsten

Gaur, Raj P. Singh

doi:10.1007/s11837-006-0082-0

Cited by 74 publications

(32 citation statements)

References 6 publications

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“…Scheelite is normally found in contact with skarn minerals with a broad variety of complex compositions or in quartz veins. Considering the mineral associations, these ores can be classified into five categories: simple scheelite, scheelite-sulphides, scheelitecassiterite, scheelite-calcite-apatite, and scheelite-powellite [3].…”

Section: Introductionmentioning

confidence: 99%

“…The mineral processing is performed both by gravity methods (coarse sizes) and by flotation (finer sizes). Cut-off grades for open-pit extraction are normally in the range 0.05 to 0.08% WO 3 , and the average grade of ores is normally from 0.2 to 0.6% WO 3 . The minimum commercial grade for concentrates without penalization is 60% in WO 3 , and the penalizing impurities are Cu, Pb, Zn, As, Bi, Mo, Sn, S, Sb, Mn and Zn.…”

Section: Introductionmentioning

confidence: 99%

“…Cut-off grades for open-pit extraction are normally in the range 0.05 to 0.08% WO 3 , and the average grade of ores is normally from 0.2 to 0.6% WO 3 . The minimum commercial grade for concentrates without penalization is 60% in WO 3 , and the penalizing impurities are Cu, Pb, Zn, As, Bi, Mo, Sn, S, Sb, Mn and Zn. Global recovery rates are not very high, normally in the interval from 50 to 70%, depending on the specificities of the ore.…”

Section: Introductionmentioning

confidence: 99%

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Direct Pressure Alkaline Leaching of Scheelite Ores and Concentrates

Leitão

Silva

Vila

et al. 2019

Mining, Metallurgy & Exploration

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The average global recovery rates for processing scheelite ores by physical methods are normally in the range 50 to 70%, and it is problematic to attain a minimum grade of 60% WO 3 in the concentrates without penalizing further this yield. Direct hydrometallurgical processing of low-grade concentrates or medium-to high-grade ores may become an interesting global economic alternative as it allows increasing the recovery rate, avoiding major penalizations due to the grade of the concentrate and increasing the added value of the final product. Leaching of scheelite by sodium carbonate presents several advantages such as its selectivity regarding the dissolution of troubling metals like iron and aluminium, allowing for a simple and flexible process diagram. However, it has the disadvantage that it is performed at high temperature and pressure with a high consumption of reagents. The feasibility of leaching is appraised by the extraction yield and selectivity, but also by the operating cost. Considering these aspects, a relevant objective of the research was to transform alkaline pressure leaching into a feasible processing alternative directly applicable to both medium-and high-grade ores and simultaneously to low-and high-grade concentrates produced by physical methods. The research used ore samples and low-grade concentrates from a typical skarn orebody as well as high-grade concentrates from a chalcopyrite-scheelite orebody. Different operating conditions were tested. Temperature, pressure and reagent concentration showed to be fundamental, but not exclusive, in determining the leaching behaviour. The operating conditions are milder than the ones generally proposed in the literature or currently in use in industry, but with higher carbonate consumptions. The research was oriented towards potential industrial implementation allowing for the application of optimization methods and straight scale-up to pilot-plan design and project.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct Pressure Alkaline Leaching of Scheelite Ores and Concentrates

Leitão

Silva

Vila

et al. 2019

Mining, Metallurgy & Exploration

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“…The former two methods are conventional processes, in which the tungstic acid or sodium tungstate obtained need to be transformed into ammonium tungstate for producing APT [1,9,10], therefor there are a great amount of wastewater together with a plenty of auxiliary materials consumption [11] due to difficult recycling of leaching reagents. The ammonium salt leaching method can directly obtain ammonium tungstate solution and thus has drawn great attention.…”

Section: Introductionmentioning

confidence: 99%

Ca3WO6 prepared by roasting tungsten-containing materials and its leaching performance

Zhou

et al. 2015

International Journal of Refractory Metals and Hard Materials

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“…One of the important steps of conventional tungsten production is the thermal decomposition of APT4 which is the product of the crystallization step. WO 3 or tungsten blue oxide (TBO) can be formed as decomposition products depending on decomposition conditions [1][2][3][4]. The thermal decomposition of APT4 shows differences under oxidizing, reducing and inert gas atmospheres so that there are many investigations which are explained in detail by Kalpakli et al [5].…”

Section: Introductionmentioning

confidence: 99%

Thermal Decomposition Reaction Mechanisms and Kinetics of Ammonium Paratungstate Tetrahydrate

Eser¹,

Kahruman²,

Yusufoğlu³

2014

Characterization of Minerals, Metals, and Materials 2014

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One of the important steps of tungsten (W) production is the thermal decomposition of ammonium paratungstate tetrahydrate (APT4, [(NH 4 ) 10 (H 2 W 12 O 42 )•4H 2 O]) which is an intermediate product of the process. In the literature, there are different findings on the thermal decomposition mechanism of APT4. The investigation of thermal decomposition kinetics of APT plays an important role in reactor and process design.In this study, the thermal decomposition mechanisms and reaction kinetics of APT4 were investigated by using thermogravimetric, differential thermal and mass spectrometric analyses (TGA/DTA/MS) under dry air and inert gas atmospheres. The characterizations of the intermediate and final products obtained in each thermal decomposition step were carried out by X-ray Powder Diffraction (XRD) and Fourier Transform-Infrared (FT-IR) analytical techniques. Decomposition reaction mechanisms were determined. Apparent activation energies were calculated for the second, third and fourth decomposition steps.

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Modern hydrometallurgical production methods for tungsten

Cited by 74 publications

References 6 publications

Direct Pressure Alkaline Leaching of Scheelite Ores and Concentrates

Direct Pressure Alkaline Leaching of Scheelite Ores and Concentrates

Ca3WO6 prepared by roasting tungsten-containing materials and its leaching performance

Thermal Decomposition Reaction Mechanisms and Kinetics of Ammonium Paratungstate Tetrahydrate

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