Abstract
Fe2As has been studied in situ by synchrotron powder X-ray diffraction (PXRD) over the range of temperatures 25–850 °C and under a neutral atmosphere to understand its thermal behavior, which is potentially important for gold extraction. For the first time, incongruent high-temperature reactions of Fe2As are observed as it breaks down and the existence of a previously undiscovered high-temperature FeAs phase with an NiAs-type structure has been determined experimentally. No evidence has been found for the existence of the high-temperature Fe3As2 phase. Hence, the previously published phase diagram for the Fe–As system has to be modified accordingly.
Highlights
Due to resource depletion of processed nonferrous and precious metals, metallurgical processing is increasingly moving toward refractory ores and concentrates with high arsenic (As) content
Iron arsenides may be the key to the extraction of gold from double refractory gold−arsenic-bearing carbonaceous ores, where gold is not extractable without significant ecological contamination from the associated arsenopyrite mineralization
There is no information on the thermal behavior of diiron arsenide in reducing and inert atmospheres, which are characteristic of the conditions of the direct reductive melting (DRM) process
Summary
Due to resource depletion of processed nonferrous and precious metals, metallurgical processing is increasingly moving toward refractory ores and concentrates with high arsenic (As) content. In this regard, the problem of As removal, and countering the problems it adds to the technological process of obtaining end product metals, becomes absolutely critical. By processing under reducing atmospheres in the presence of an iron-rich slag, certain proposed direct reductive melting (DRM) processes lock As into iron arsenide phases.[1] The effectiveness of As removal from arsenic-bearing gold concentrates is directly associated with the decomposition of such iron arsenides. There is no information on the thermal behavior of diiron arsenide in reducing and inert atmospheres, which are characteristic of the conditions of the DRM process
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