Sulphur from sulphide ores

A further method of obtaining sulphur from sulphide ores consists in heating the latter under high vacuum the sulphur vaporises and is condensed in a suitable receiver.2... 

During the formation of a sulphide mineral deposit there is usually the development of a primary sulphide halo in the host rock. Subsequent to ore formation, sulphide anions and compounds may be dispersed in the aqueous phase in groundwater and the gas phase in air-filled pore spaces to form secondary dispersion patterns. In exploration for sulphide mineral deposits, the simple determination of mobile sulphur species originating from sulphide ore deposits has a clear attraction. In order to understand the way in which such sulphur species occur in soils, a number of in-vitro experiments were performed. On the basis of the results, suitable methods of sampling and analysis have been chosen and tested in soils overlying 30 different mineral deposits. 

Similar considerations apply to the metal sulphides. Good thermochemical quantities for sulphur in dilute solution in transition metals are conspicuously absent. Recovery of small amounts of selenium and tellurium from sulphidic ores is gaining interest. Whether this position warrants an extensive study of the thermochemistry of compounds of selenium and tellurium is difScult to say. For the time being, the available information suffices. 

Occurrence.—Although a relatively rare element, selenium is fairly widespread in nature,1 being frequently found in small quantities both in the combined state in pyrites and sulphide ores 2 and also in the free state in the volcanic sulphur deposits 3 of Italy, Hawaii and the Lipari Islands. In the sulphur deposits the selenium is usually present in the form of an isomorphous mixture with the sulphur. Its occurrence in Swedish pyrites (from Falun) led to the discovery of the element by J. J. Berzelius in 1817,4 during an examination of the deposit formed in the lead chambers of a sulphuric acid plant. Owing to the striking chemical resemblance of the new element to tellurium (see p. 351), Berzelius assigned it the name selenium (Gk. selene, the moon), which, in order to indicate the metalloid nature of the element, is sometimes modified into selenion. 

Jumau s process (ut supra) for the electrolytic extraction of copper from its ores is also applicable to the production of pure copper from solutions of its compounds.8 The cupric sulphite or cupro-cupric sulphite precipitated from the copper solution by the action of sulphurous acid or a sulphide is decomposed by sulphuric acid into cupric sulphate and metallic copper. The metal thus liberated is pressed into a form suitable for an anode, and refined electrolytically. 

Selenium (9 x % of the earth s crust) occurs in small quantities in sulphide ores, particularly FeS2. It is extracted from the flue dusts produced in the roasting of sulphide ores and from the lead chamber mud formed in sulphuric acid manufacture, as a solution in aqueous KCN. It is precipitated from the filtered solution by the addition of HCl. 

Relatively close to the term "geochemical engineering" is the technique of bacterial leaching. The technique is known for a long time from the treatment of metal-poor ores, where hydro- or pyrometallurgy is no more economically feasible. During these processes - mediated by specialized bacteria - oxidation of sulphur and sulphides produces sulphuric acid, and metals are mobilized such as copper. 

Falconbridge process A selective leaching process used to extract copper and nickel from a sulphide ore containing nickel, copper, and other precious metals that has been roasted to remove the sulphur known as matte. The nickel is removed using hydrochloric acid and recovered as nickel chloride crystals. The residue is then leached with sulphuric... 

Figure 10.11 presents the sehematic flowsheets of potential controlled flotation separation to recover chalcopyrite and pyrite from a copper-sulphur ore. Flowsheet I is collectorless flotation of chalcopyrite and then collector floatation of pyrite. Flowsheet II is collectorless flotation of chalcopyrite and then sodium sulphide-induced flotation of pyrite. Batch flotation results are illustrated in Table 10.5. It is evident that both flowsheets are suitable for flotation separation of copper-sulphur ore. The feed ore assayed 0.38% Cu and about 6% S, the copper concentrate obtained assayed 18%- 19% Cu with a recovery of 89%. For sulphur concentrate, the grade is 37%-43% S with a recovery of 82% - 85%. Interestingly, flie grade of sulphur concentrate is higher using sodium sulphide induced flotation than collector flotation. 

Ghosh, S., Thorpe, R.I., Ghosh, A.K. 1999. Lead and sulphur isotope geochemistry of galena from Sargipali sulphide deposit, Sundergarh, Orissa -Implications for ore genesis. Indian Journal of Earth Science, 26, 1-12. 

The principal ore of toerenry is the sulphide—tho Annober of the Gormans and minium of Pliny. The color of native cinnabar varies from coehineal red to brownjsh-Ted and leaden grey. The.streak is scarlet, and the lustre usually adamantine. The density of this mineral is 8-098, and when pure it contains 86-29 parts of mercury with 13-71 of sulphur. Specimens of the purest ore have, occasionally,. all the richness of hue which the best vermilion presents. 

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