Mercury sulphide minerals

Quite frequently the natural surface of a mineral requires preliminary chemical treatment before it will form the surface film required for collection One of the commonest instances of this is with sphalerite (zinc sulphide), which does not float properly when treated with xanthates. If, however, it is given a preliminary treatment with dilute copper sulphate solution, a very small amount of copper sulphide is deposited on the surface and the ore becomes floatable, the surface being now capable of reaction with xanthates. Such treatment is usually termed activation in general, an activating solution for a sulphide mineral should contain a metallic ion whose sulphide is less soluble than that contained in the mineral for zinc sulphides, silver, copper, mercury, cadmium, and lead salts are all effective activators. 

The dithizone method has been used in determination of mercury in natural waters [80], coal and its products [81], sulphide minerals [82], silver [12], tin [10], cadmium [83], uranium compounds [84] selenium [85], Hg-Cd-Te thin films [86], foodstuffs [87,88], and water... 

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. 

The stibmlphide is the cethiops mineral of the older chemists, and was prepared by agitating a little water, sulphur, and mercury, in equal proportions, in a mortar, or at a slightly increased heat, till a black powder resulted.. It oan bo obtained by transmitting a stream of sulphide of hydrogen ges through a dilute solution of subnitrate of mercury in the cold, when a subsulphide of a black color falls. The reaction is as follows... 

After removing the mercury metal by filtration, black mercury(II) sulphide can again be precipitated by acidification with dilute mineral acids ... 

Typical mercury contents of common silicate, sulphide and gangue minerals (from Kleinevoss, 1971)... 

Friedrich, G.H. and Hawkes, H.E., 1966. Mercury dispersion haloes as ore guides for massive sulphide deposits. West Shasta District, California. Mineral. Deposita, 2 77-88. 

Ozerova, N.A., Rusinov, V.L. and Ozerov. Y.K., 1975. The mercury in sulphide deposits emplaced in volcanic suites. Mineral. Deposita, 10 228-233. 

Arsenic is sometimes found in nature in native state and is fairly easily extracted from its compounds. It is not known who was the first to produce elemental arsenic. Usually its discovery is ascribed to the alchemist Albert the Great. Paracelsus described the process of preparing metallic arsenic by the calcination of arsenic with egg-shells. According to some reports, metallic arsenic was known much earlier but it was considered to be a variety of native mercury. This is due to the fact that arsenic sulphide resembles one of mercury minerals and the extraction of arsenic from its ores is rather simple. 

Mercury (Hg) occurs naturally as the sulphide in the ore known as cinnabar, and also in the metallic form quicksilver. It is mined chiefly in Spain, but also in Italy, Russia, USA and elsewhere. The ore is not particularly hazardous to miners, as the sulphide is insoluble. Risk is greater in other industries, such as in the manufacture of sodium hydroxide and chlorine, electrical and scientific instruments, fungicides, explosives, paints and in dentistry. 

In a second method air (500 litres) is drawn at 33.3 litres per minute through a glass-fibre pad treated with cadmium acetate and sodium sulphide. The pad is then removed for determination of mercury. The active carbon or the cadmium sulphide pad is ignited in the apparatus of Sargeant et al, the absorbent replacing the iodised carbon and the mineral wool being omitted. The color produced on selenium sulphide test paper is compared with a color chart. Both methods are applicable to the determination of ethylmercury dicyanidiamide, The first method only, is applicable to diethylmercury. 

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