Thermal studies on chromium(II) salts

Crouse, Karen A.; Badri, M.

doi:10.1016/0040-6031(91)80100-w

Cited by 4 publications

(2 citation statements)

References 10 publications

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“…The onset of decomposition of iron, chromium and aluminium sulphates occurs at temperatures ranging between 500-600 °C (Bayer et al, 1982;Krouse et al, 1991;Tagawa, 1984), while that of magnesium sulphate is from 850 °C (Tagawa, 1984). MT tct formed at 550 °C contained very little, if any, NH 3 , as confirmed by the absence of mass loss (TGA) and by endothermic peaks (DTA) between 350 °C -400 °C.…”

Section: Preliminary Thermochemical Treatment (Static Furnace)mentioning

confidence: 87%

Process development for elemental recovery from PGM tailings by thermochemical treatment: Preliminary major element extraction studies using ammonium sulphate as extracting agent

et al. 2016

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Section: Preliminary Thermochemical Treatment (Static Furnace)mentioning

confidence: 87%

Process development for elemental recovery from PGM tailings by thermochemical treatment: Preliminary major element extraction studies using ammonium sulphate as extracting agent

et al. 2016

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“…Dissociation of ammonium metal sulphate phases into their respective metal sulphate phases is known to occur between 450 -550 °C [36], and this phenomenon was observed in MTtct formed using (NH4)2SO4 at ≤ 500°C and NH4HSO4 at ≤ 450°C. The onset of decomposition of Fe, Cr and Al sulphates (FeSO4/Fe2(SO4)3, Cr2(SO4)3.xH2O, Al2(SO4)3) occurs at temperatures ranging between 500-600 °C [36][37][38], while that of Mg sulphate (MgSO4) takes place from 850 °C [39]. Although the TG curves of MTtct obtained from the sulphate salts exhibited similarities, a smaller mass loss was observed for MTtct using NH4HSO4 compared to (NH4)2SO4, regardless of the reaction temperature.…”

Section: Treatment Experimentsmentioning

confidence: 99%

Thermochemical treatment of platinum group metal tailings with ammonium salts for major element recovery

Mohamed

Lehong

Merwe

et al. 2019

J Therm Anal Calorim

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It was recently demonstrated that the extraction of major elements from South African Platinum Group Metals (PGM) tailings can be achieved via thermochemical treatment with ammonium sulphate followed by aqueous dissolution. The current study uses the insight gained from the previous work and investigates and compares major element extraction efficiencies obtained using ammonium sulphate and three other ammonium salts (ammonium bisulphate vs ammonium chloride vs ammonium nitrate) as extracting agents at five different temperatures (350 to 550 °C).Overall, ammonium sulphate was the most promising reagent for the co-extraction of major elements, with the best extraction efficiencies achieved for aluminium (ca. 60%) and calcium (ca. 80%), alongside chromium (ca. 29%), iron (ca. 35%), magnesium (ca. 25%) and silicon (ca. 32%). In contrast, ammonium chloride and ammonium nitrate extracted smaller quantities of these elements, in particular chromium which was hardly extracted (≤ 1.2%), whereas calcium was nearly equally extracted for all salts (70-80%). It could not be ascertained whether the plagioclase phase, as anorthite, reacted with ammonium salts during the thermochemical step, but it was found to dissolve nearly completely during the acid leaching step in the absence of thermochemical processing. This phase was the main contributor to calcium and aluminium in solution. The greatest effect of temperature was on the flowability characteristic of the reaction product after treatment rather than on elemental extraction efficiencies. Thermochemical treatment using ammonium sulphate represents the most promising route for extracting valuable elements from PGM tailings, which could be subsequently converted to value-added products.

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Chromium

Lay

Levina

2003

Comprehensive Coordination Chemistry II

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Thermal studies on chromium(II) salts

Cited by 4 publications

References 10 publications

Process development for elemental recovery from PGM tailings by thermochemical treatment: Preliminary major element extraction studies using ammonium sulphate as extracting agent

Process development for elemental recovery from PGM tailings by thermochemical treatment: Preliminary major element extraction studies using ammonium sulphate as extracting agent

Thermochemical treatment of platinum group metal tailings with ammonium salts for major element recovery

Chromium

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