Formation and recognition of alkyl xanthyl thiosulphates in sulphide ore flotation liquors |
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| Authors: | MH Jones JT Woodcock |
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| Institution: | CSIRO Division of Mineral Chemistry, P.O. Box 124, Port Melbourne, Vic. 3207 Australia |
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| Abstract: | Alkyl xanthyl thiosulphates (R.OCSS.S2O3?) (RXT?) are formed in solution by mild oxidation (e.g. by I2) of solutions containing both xanthate and thiosulphate. They can also be formed by reaction of Cu2+ with xanthate and thiosulphate, reaction of dixanthogen with thiosulphate, and by reaction of xanthate with tetrathionate; these last three reactions can occur in flotation pulps in slightly acid or alkaline solutions (pH 5–10).Alkyl xanthyl thiosulphates are stable in acid and neutral solution; the solutions have a UV absorption maximum at 289 nm. In strongly alkaline solution (pH 12) RXT? decomposes within a few minutes to yield a xanthate (mostly) plus a little perxanthate. At pH 10 this decomposition to xanthate takes about 48 h. At pH 7–9 RXT? is relatively stable. RXT? is not extracted from aqueous solution with common solvents (chloroform, iso-octane, cyclohexane, or ether). It forms a water-insoluble adduct with cetyltrimethyl-ammonium bromide (CTAB); this adduct can be extracted into chloroform, and the extract has a UV absorption maximum at 296 nm.RXT? was found in solutions from the gangue-sulphide flotation section at Renison Ltd, the zinc flotation circuit and the copper flotation circuit at Mount Isa Mines Ltd, and the lead flotation section of The Zinc Corporation Ltd. The presence of RXT? in operating flotation plants has various practical and theoretical implications. |
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