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Purification of molybdenite concentrates
2008 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

A molybdenite flotation concentrate was refined by selective removal of copper impurity with minimum dissolution of molybdenum in the concentrate. Copper is present in the concentrate mainly as copper sulphide, chalcopyrite. Investigations were carried out on the removal of the sulphide by their selective leaching in sodium cyanide, ferric chloride and ferric sulphate solutions. Approximately 80 to 100% of the copper concentration was removed under optimum conditions with sodium cyanide and ferric chloride solutions with little dissolution of molybdenum while ferric sulphate solution was ineffective due to a number of factors such as passivation of chalcopyrite, temperature and redox potential. Leaching with sodium cyanide was carried out with stoichiometric concentration of the salt, 20% solids, at ambient temperature and pH above11 with oxygen as oxidative gas, for 53 and 74 hours. Ferric chloride leaching was carried out at 35% solids with 10% ferric chloride, 1% cupric chloride, 20% calcium chloride all by weight of solution at an average temperature of 80oC and pH about zero for 4 hours. Ferric sulphate leaching was carried out with stoichiometric concentration of ferrous sulphate as the starting solution in which ferric sulphate solution was generated by oxidation with addition of oxygen and sulphur dioxide in ratio 10:1, 10% solids and pH below 0.5 at 65oC for 5 hours. The intermediate pregnant solution samples and final leach solutions from the tests were analyzed for dissolved copper with the aid of atomic absorption spectrophotometer, (AAS) and the purified concentrate (solid residue) was analyzed for molybdenum, copper and other important elements with different analytical techniques such as: (i) AAS for molybdenum, calcium, bismuth and low level copper, iron and lead. (ii) Solution X-ray for high-level copper, iron and lead. (iii) Fire assay for gold and silver. (iv) Leco-owen for sulphur. (v) Field ionization mass spectroscopy, (FIMS) instrument for mercury and (vi) Selective electrode for chloride ion.

Place, publisher, year, edition, pages
Keyword [en]
Physics Chemistry Maths, molybdenite, leaching, cyanidation
Keyword [sv]
Fysik, Kemi, Matematik
URN: urn:nbn:se:ltu:diva-52775ISRN: LTU-PB-EX--08/012--SELocal ID: 9de0ff9f-4fb0-4e1d-bedb-795b8678e3c6OAI: diva2:1026147
Subject / course
Student thesis, at least 30 credits
Educational program
Chemical Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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