Patent
Method for extracting tungsten from scheelite
Zhongwei Zhao,Jiangtao Li +1 more
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TLDR
In this article, a method for extracting tungsten from scheelite, which comprises: introducing mixed acid consisted of sulfuric acid and phosphoric acid into a decomposition reactor, heating to 70-100?, and then adding scheelsite, maintaining the solid-liquid ratio at 3:1-8:1L/kg.Abstract:
Disclosed is a method for extracting tungsten from scheelite, which comprises: introducing mixed acid consisted of sulfuric acid and phosphoric acid into a decomposition reactor, heating to 70-100?, and then adding scheelite, maintaining the solid-liquid ratio at 3:1-8:1L/kg, filtrating after 1-6h of reaction, crystallizing the obtained filtrate which is compensated with sulfuric acid consumed by the reaction to obtain phosphotungstic acid crystal, dissolving phosphotungstic acid crystal in water and transforming it to obtain ammonium tungstate solution containing 200-300g/L of WO3, which is used for preparing APT, while returning the obtained crystal mother liquor for ore leaching after being compensated with phosphoric acid and water to the initial level. The invention saves cost of phosphorus-removal reagent and loss of Tungsten; is capable of high efficient scheelite leaching at normal pressure, and overcomes the problems such as Cl- corrosion and heavy volatilization of HCl in traditional acid decomposition process; realizes the recycling of phosphoric acid in general, and greatly reduces the cost of leaching and the quantity of wastewater discharging; and has short flow process, convenient operation, and is adaptive for industrial application.read more
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Journal ArticleDOI
Sustainable and Efficient Recovery of Tungsten from Wolframite in a Sulfuric Acid and Phosphoric Acid Mixed System
TL;DR: The innovative technology of co-leaching scheelite concentrates by a mixture of sulfuric acid and phosphoric acid is an environmentally friendly and low-cost technology as discussed by the authors.
Journal ArticleDOI
Nature of Monomeric Molybdenum(VI) cations in acid solutions using theoretical calculations and raman spectroscopy
Ning Zhang,Ning Zhang,Erich Königsberger,Siqi Duan,Ke Lin,Hai-Bo Yi,Dewen Zeng,Zhongwei Zhao,Glenn Hefter +8 more
TL;DR: The composition and structures of the two protonated species formed from uncharged molybdic acid in strongly acidic solutions have been investigated using a combination of density functional theory calculations, first-principles molecular dynamics simulations, and Raman spectroscopy and it is shown that both protonate species maintain the original octahedral structure of molyBDic acid.
Journal ArticleDOI
Pressure leaching of wolframite using a sulfuric-phosphoric acid mixture
TL;DR: In this article, tungsten was extracted from wolframite using sulfuric-phosphoric acid mixtures, and the results showed that after leaching, the residue contained unleached wolframites, quartz, small amounts of calcium sulfate (anhydrite) and phosphotungstate salts.
Journal ArticleDOI
Extraction behaviors of rare-earths in the mixed sulfur-phosphorus acid leaching solutions of scheelite
TL;DR: In this article, the authors examined the complexing ability of rare-earth ions in scheelite leachate and found that rare-element ions were mainly complex with unsaturated phosphotungstic acid to form stable anions in the solution.
Patent
Method for extracting tungsten from raw materials containing wolframite
TL;DR: In this paper, a method for extracting tungsten from raw materials containing wolframite was proposed, which comprises the following steps of adding a calcium substance containing phosphorus in the ore grinding process of the raw materials.
References
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Calcium Sulfate Dihydrate Nucleation in the Presence of Calcium and Sodium Chloride Salts
TL;DR: In this article, a batch crystallizer with a related optical device at a supersaturation ranging from 2 to 4 and a fixed temperature T = 25 °C was used for primary nucleation.
Patent
Extracting tungsten from ores and concentrates
TL;DR: In this article, a process for recovering tungsten from bearing ores comprises producing a concentrate from the ore and leaching the concentrate at atmospheric pressure in a strong mineral acid solution, for example, a solution of sulfuric acid, hydrochloric acid or nitric acid within a temperature range of from 40° to 90 Centigrade for from one to four hours in the presence of an inorganic complexing agent.
Patent
Method for decomposing scheelite
TL;DR: In this article, a method for decomposing scheelite is proposed, where scheelites are decomposed by employing nitric acid, so that Ca in the scheelsite can enter the solution in a form of soluble calcium nitrate; meanwhile, phosphoric acid or phosphorite serve as a tungsten complexing agent.
Patent
Method for extracting tungsten from scheelite and producing high-quality calcined gypsum
TL;DR: In this paper, a method for extracting tungsten from scheelite and producing high-quality calcined gypsum, comprising the following steps: adding a mixed acid of phosphoric acid and sulphuric acid to decompose scheelites; and after decomposition, adding hydrated gpsum seed crystals to finish the dewatering conversion process of dihydrate gypsumin to obtain hydrated gypsumar with good properties.
Patent
Processing of calcium-containing tungstenic ore
TL;DR: In this paper, the process of adding phosphate or phosphoric acid to the sodium hydroxide leach solution, so that, at the same time as wolframite is leached out by scheelite is also dissolved, calcium is converted to the calcium hydroxyphosphate and precipitated, while tungsten passes into solution in the form of sodium tungstate.