Sulphide concentrate

Table 5.32 Typical effects or hydrogen sulphide concentrations in air...

Figure 4.8 Flowsheet for copper extraction from sulphide concentrates.

Jappinen P, Tenhunen R. 1990. Hydrogen sulphide poisoning Blood sulphide concentration and changes in haem metabolism. Br J Ind Med 47 283-285. 

McCarron et al. (1990) used the X-ray photoelectron spectroscopy to analyze chalcopyrite and pyrite surface after being conditioned in sodium sulphide solutions. They found that multilayer quantities of elemental sulphur were produced at the surface of both minerals in 3 x 10 and 3 x 10" mol/L sulphide solutions although for a given sulphide concentration, the surface coverage of elemental sulphur for p)uite was greater than that for chalcopyrite under open circuit conditions. Eliseev et al. (1982) concluded that elemental sulphur was responsible for the hydrophobicity of pyrite and chalcopyrite treated with sodium sulphide. Luttrell and Yoon (1984a, b) observed a shoulder due to elemental sulfixr near 164 eV in the S (2p) spectra from relatively pure chalcopyrite floated after being conditioned at different pulp potential established by different hydrosulphide concentration. 

The Ag2 S ISE has Nemstian response dE/d log a( = 0.0296 V in the sulphide concentration range 10" to 10" M and silver ions from 10 to 10 M if the solutions are prepared from pure salts, as a further concentration decrease is prevented by adsorption on the glass (see p. 76 and [87, 163]). After prolonged use, the limit of the Nemstian behaviour shifts to about 10" m [130] as a result of formation of mixed potentials on accumulation of metallic silver in the membrane surface. An analogous deterioration in the membrane function in the presence of iodine results from surface oxidation [23]. Cyanide interferes only at large concentrations the equilibrium constant of the reaction... 

It should be kept in mind that many of these decomposition reactions are equilibria. The decomposition of thiourea in the absence of a metal ion will normally be much slower than in the presence of such an ion. The metal ion removes sulphide as metal sulphide—the less soluble the sulphide, the more effective the removal at very low sulphide concentrations. This continuous removal of sulphide shifts the equilibrium to the direction of more sulphide production. The same principle holds for many other anion precursors. 

In the classical pyrometallurgical smelting of metal sulphide concentrates most of the sulphur is driven off as sulphur dioxide. This process is becoming increasingly unacceptable from an environmental point of view. An alternative is to process the concentrates using hydrometallurgical techniques. 

Temporal variations in the average depth of the chemocline in the Black Sea and the upper sulphide boundary particularly are mainly the result of climatic changes in the density structure of the water column. The upper anoxic boundary location versus density for this basin did not change over the period from 1910 to 1995. However, recent data have shown a prominent increase in sulphide concentrations, as well as nutrient levels, within the anoxic zone supposedly due to anthropogenic impacts or climatic variations. 

Metal sulphides Sulphide produced in bacterial sulphate respiration can precipitate heavy metal ions from solution when the sulphide concentration is in excess of that demanded by the solubility product of the... 

Sulphide concentrations in the blood of unexposed subjects are usually less than 0.05 LLg/ml. Fatalities have been associated with concenhations between 1 and 5 LLg/ml which indicate ingestion of about 10 g of a soluble sulphide. 

Turner S. M., Nightingale P. D., Spokes L. J., Liddicoat M. 1., and Liss P. S. (1996) Increased dimethyl sulphide concentrations in sea water from in situ iron enrichment. Nature 383, 513-517. 

Torma, A.E. and Subramanian, K.N., 1974. Selective bacterial leaching of a lead sulphide concentrate. Int. J. Miner. Process., 1 125—134. 

Sodium Sulphide.—Concentrated from 8 to 45 per cent in single or multiple-effect evaporators of the horizontal-tube or rapid-circulation type, with a steam pressure of 5 lb. and a vacuum of 26 in., at the rate of IK to 2 gal. per square foot. Evaporators are of cast iron with tubes of charcoal iron or steel. Sometimes the hquor is further concentrated to 60 per cent in the Mantius high which is equipped with cast-iron tubes. 

The sulphide concentration should be as high as possible early in the cook. Hydrosulphide reactions, liberating phenolic hydroxyls, render lignin more... 

The iodide method was used in determinations of bismuth in pharmaceuticals [66], sea water, A1 and Bi alloys [37], organic compounds [67], lead and its alloys [1,26], copper and its alloys [1,29,68], cast iron and steel [69], antimony [70], and sulphide concentrates [1]. After extraction of the iodide complex with various organic cations, Bi was determined in water and soil [32], pharmaceuticals [31], soil and ores [33], and copper alloys [31]. 

In November 2002, we found a large number of living microalgae species on silty sediment surfaces covering the lake bottom to depths of more than 20 m, independent of dissolved hydrogen sulphide concentration at the sediment—water... 

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