Zinc sulphide activity

Some oxide-type minerals have been found to luminesce when irradiated. A simple example is ruby (aluminium oxide with chromium activator), which emits bright-red light. The phosphors are incorporated into colour television screens to emit the colours blue (silver-activated zinc sulphide), green (manganese-activated zinc orthosilicate), and red (europium-activated yttrium vanadate). 

Pozzo, R. L., Malicsi, A. S., Iwasaki, L, 1988. Pyrite-pryyhotite-grinding media contact and its effect on flotation. Minerals Metallurgical Processing, 5(1) 16-21 Pozzo, R. L., Malicsi, A. S., Iwasaki, I., 1990. Pyrite-pyrrhotite-grinding media contact and its effect on flotation. Minerals Metallurgical Processing, 7(1) 16 - 21 Prestidge, C. A., Thiel, A. G., Ralston, J., Smart, R. S. C., 1994. The interaction of ethyl xanthate with copper (II)—activated zinc sulphide kinetic effects. Colloids Surfece, A. Physicochem. Eng. Aspects, 85 51 - 68... 

Prestidge, C. A., Skinner, W. M., Ralston, J., Smart, R. S. C., 1997. Copper (II) activation and cyanide de-activation of zinc sulphide under mildly alkaline conditions. Appl. Siuf. Sci., 108 333-344... 

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. 

Discussion Zinc sulphide is characterized by being the only common white sulphide and by being insoluble in acetic acid but soluble in more active acids, such as hydrochloric or sulphuric acids. These characteristics may be made use of in recognizing compounds of zinc. 

For a substance to act as an activating agent, it must react with natural substances to produce one or more soluble substances that increase the cation and anion contents of water. For example, zinc sulphide is an activating agent as it produces highly soluble zinc sulphate which increases Zn into water. But the clay minerals rarely act as activating agents in nature, as explained below. 

The scintillation or Lucas cell (Lucas, 1957) is made by coating the inside of a Plexiglass, quartz or metal cell with silver-activated zinc sulphide (ZnS[Ag]). After transferring the Rn to the cell, it is stored for 1-2 h to allow Rn daughters, Po, Pb, and Po to equilibrate partially. Alpha decays from Rn, Po and Po cause emissions of photons from the ZnS[Ag]. These are converted into electrical signals using a photomultiplier tube (PMT) attached to the cell and routed to a counter. 

If the compound contains an active cobalt-containing adhesion promoter, metallic cobalt precipitates onto the brass surface and also forms the Me-S bond, in addition to copper. Zinc can also form this bond, but does not bond to rubber, as the zinc sulphide growth rate is low (see stage IV). The role of cobalt in NR skim stocks is thus to activate (or... 

Zinc smelting activity in India has been traced to 100 BC which continued till the first quarter of the 19th centiWiry. 10 llArchaeological brass finds in Taxila dating back to 400 BC showed on analysis that the alloy was a product of fusion of copper and metallic zinc. 10 Recent excavations at Zawar, Rajasthan, of old sphalerite (zinc sulphide ore) mines revealed, on radiocarbon assay of timber supports found at a depth of 100 meters, that the mining activity went back to BC 120 to AD 30 and the possiblity that it might as well go back... 

Sulphide-type phosphors are produced from pure zinc or cadmium sulphide (or mixtures thereof) and heating them together at about 1000 °C with small quantities (0.1-0.001 per cent) of copper, silver, gallium, or other salts, which are termed activators. 

Copper-activated zinc and cadmium sulphides exhibit a rather long afterglow when their irradiation has ceased, which is favourable for application in radar screens and self-luminous phosphors. 

Arsenic occurs primarily in sulphide minerals associated with copper ores, and to a lesser extent with zinc, lead and gold ores. Arsenic is produced as a by-product of the smelting of these metals. Primary arsenic production has now ceased in the USA and Europe, and most arsenic is now imported from China and Mexico. The volatility of arsenic represents a significant concern, and there is at present no known natural mechanism by which arsenic is immobilized in the environment. Anthropogenic activities account for an input of some 19000 tonnes into the atmosphere, compared with 12000 tonnes from natural processes, such as volcanism and forest fires (Ayres and Ayres, 1996). 

Modifiers in the flotation of sulphide minerals mainly include depressants and activators. A depressant is defined as a reagent which inhibits the adsorption of a collector on a given mineral or adsorbed on the mineral to make the siuface hydrophilic, and includes inorganic depressants such as lime, sodium cyanide, sulphin dioxide, zinc sulphate, sodium sulphide etc., and organic depressants such as sulfhydryl acetic acid, polyacrylamide polymers containing various functional groups etc. In this chapter, roles of depressants in the flotation sulphide minerals will be discussed and some new organic depressants will be introduced. 

Abstract Two systems are discussed in this chapter, which are copper activating zinc-iron system with and without depressants. Firstly, the system in the absence of depressants is discussed. And it is obtained that at a specific pH the activation for each mineral occurs in a certain range. Through the electrochemical methods and surface analysis the entity contributing to the activation can be identified which are usually copper sulphides and vary for different minerals. Secondly, the system with depressants is researched. And also the effects of pulp potential on the activation are discussed. The same conclusion can be obtained as the one from the former system. Furthermore, zeta potential are involved in the discussion of activation and die mechanism can be explained firom the changes of zeta potential. Similarly, the activation mechanism of this system is also studied through solution chemistry, bonding of activator with mineral surfaces and surface analysis. 

Electrochemical Mechanism of Copper Activating Zinc-Iron Sulphide Minerals... 

Activation of Copper Ion on Flotation of Zinc-Iron Sulphide Minerals in the Presence of Depressants... 

The influence of copper ion on the flotation of zinc-iron sulphide minerals in the presence of depressant with butyl xanthate l.Ox 10 mol/L as a collector is presented in Fig. 6.11 to Fig. 6.14. It can be seen from Fig. 6.11 and Fig. 6.12 that in the presence of 120 mg/L 2-hydroxyl ethyl dithio carbonic sodium (GXl) and 2,3 dihydroxyl propyl dithio carbonic sodium (GX2), marmatite is activated by copper ion and exhibits very good flotation with a recovery above 90% in the pH range of 4-8. The flotation of arsenopyrite and pyrrhotite is poor with a... 

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