Zinc sulphide

Because of low Mohs hardness. ZnS pigments cause virtually no wear on moulds and do not impair the mechanical strength of fibre-reinforced plastics (in contrast to abrasive pigments such as Ti02). Their main applications are in thermosetting compounds, glass fibre-reinforced thermosets and thermoplastics, and polyolefins. 

Compared with rutile titanium dioxide, zinc sulphide offers white pigments for plastics that are non-abrasive, catalytically inactive, dry lubricants. They can reduce friction, polymer decomposition, and the wear of processing equipment. 

Partial substitution of Ti02 pigments with double the quantity of ZnS does not impair brightness, pigment dispersion, or melt flow index of a masterbatch, but reduces friction and abrasion and increases temperature stability. It can thus act as a processing aid, especially in linear LDPE. 

The pigments are, for all practicable purposes, free of heavy metals they are listed in the US FDA Code of Federal Register (Part 178) and meet the pigments Recommendation IX of the German Federal Health Ministry (EGA), but not the French Circulaire No. 176 (dated 2 December 1959), which sets a maximum limit of 0.2% for acid-soluble zinc. 

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Potassium chloride actually has the same stnicture as sodium chloride, but, because the atomic scattering factors of potassium and chlorine are almost equal, the reflections with the indices all odd are extremely weak, and could easily have been missed in the early experiments. The zincblende fonn of zinc sulphide, by contrast, has the same pattern of all odd and all even indices, but the pattern of intensities is different. This pattern is consistent with a model that again has zinc atoms at the comers and tlie face centres, but the sulphur positions are displaced by a quarter of tlie body diagonal from the zinc positions. 

Zinc oxide or zinc white is used in paints, but more preferable, because of its better covering power, is lithopone (a mixture of zinc sulphide and barium sulphate). Both paints have the advantage over white lead that they do not blacken in air (due to hydrogen sulphide). Zinc dust and also zinc chromate are constituents of... 

Addition of sulphide ion to a solution of a zinc salt containing ammonia and ammonium chloride gives a white precipitate of zinc sulphide. 

Sulphur. Moisten the centre of a filter-paper with lead acetate solution. Then add about 10 ml. of dilute hydrochloric acid to the residue in the evaporating-basin, and at once cover the latter with the paper. If zinc sulphide is present in the residue, the hydrogen sulphide evolved will give a definite daA brown coloration with the lead acetate paper. The presence of hydrogen sulphide can often be confirmed by its odour. 

When an organic compound is heated with a mixture of zinc powder and sodium carbonate, the nitrogen and halogens are converted into sodium cyanide and sodium hahdes respectively, and the sulphur into zinc sulphide (insoluble in water). The sodium cyanide and sodium hahdes are extracted with water and detected as in Lassaigne s method, whilst the zinc sulphide in the residue is decomposed with dilute acid and the hydrogen sulphide is identified with sodium plumbite or lead acetate paper. The test for nitrogen is thus not affected by the presence of sulphur this constitutes an advantage of the method. 

The objective in die roasting of sulphides, such as copper sulphides and zinc sulphides, is to convert these into their coiTesponding oxides by reaction with... 

It appears that the zine salt funetions by preferentially reaeting with sulphur to form white zinc sulphide rather than coloured eadmium sulphide and thus helps to reduce colour in the compound. 

Staeking faults and sometimes proper polytypism are found in many inorganic compounds - to pick out just a few, zinc sulphide, zinc oxide, beryllium oxide. Interest in these faults arises from the present-day focus on electron theory of phase stability, and on eomputer simulation of lattice faults of all kinds investigators are attempting to relate staeking-fault concentration on various measurable character-isties of the compounds in question, such as ionicity , and thereby to cast light on the eleetronic strueture and phase stability of the two rival structures that give rise to the faults. 

Vernon claims that in outdoor atmospheres the corrosion product consists largely of zinc oxide, hydroxide and combined water, but also contains zinc sulphide, zinc sulphate and carbonate. The following table gives the composition of typical films formed in an industrial atmosphere. 

Appreciable errors may also be introduced by post-precipitation. This is the precipitation which occurs on the surface of the first precipitate after its formation. It occurs with sparingly soluble substances which form supersaturated solutions they usually have an ion in common with the primary precipitate. Thus in the precipitation of calcium as oxalate in the presence of magnesium, magnesium oxalate separates out gradually upon the calcium oxalate the longer the precipitate is allowed to stand in contact with the solution, the greater is the error due to this cause. A similar effect is observed in the precipitation of copper or mercury(II) sulphide in 0.3M hydrochloric acid in the presence of zinc ions zinc sulphide is slowly post-precipitated. 

Sanders BW, Kitai AH (1990) The electrodeposition of thin film zinc sulphide from thiosulphate solution. J Cryst Growth 100 405 10... 

Morris GC, Vanderveen R (1992) Electrodeposited cadmium zinc sulphide films for solar ceUs. Sol Energy Mater Sol CeUs 26 217-228... 

The arrangement of oxygen atoms in ice I is isomorphous with the wurtzite form of zinc sulphide, and also with the silicon atoms in the tridymite form of silicon dioxide. Hence, ice I is sometimes referred to as the wurtzite or tridymite form of ice (Eisenberg Kauzmann, 1969). 

Acids, when used as scale inhibitors, are extremely corrosive. Their effectiveness has been laboratory tested. Parameters include acid type, metallurgy, temperature, inhibitor type and concentration, duration of acid-metal contact, and the effect of other chemical additives [279]. Lead and zinc sulphide scale deposits can be removed by an acid treatment [922]. 

M. M. Jordan, K. Sjursaether, R. Bruce, and M. C. Edgerton. Inhibition of lead and zinc sulphide scale deposits formed during production from high temperature oil and condensate reservoirs. In Proceedings Volume. SPE Asia Pacific Oil Gas Conf (Brisbane, Australia, 10/16-10/18), 2000. 

Dhas Aral N, Zaban A, Gedanken A (1999) Surface synthesis of zinc sulphide nanoparticles in silica microspheres sonochemical preparation, characterisation and optical properties. Chem Mater 11 806—813... 

There are new ideas and experiments on the rTCA cycle. A group from Harvard University studied some reaction steps in the rTCA cycle which were kept going by mineral photochemistry. The authors assumed that solar UV radiation can excite electrons in minerals, and that this energy is sufficient to initiate the corresponding reaction steps. In this photocatalytic process, semiconductor particles were suspended in water in the presence of a zinc sulphide colloid (sphalerite) the experiments were carried out in a 500 mL reaction vessel at 288 K. Irradiation involved a UV immersion lamp (200-410 nm) in the photoreactor. Five reactions out of a total of 11 in the rTCA cycle were chosen to check the hypothesis ... 

A co-precipitated mixture of approximately 28% zinc sulphide, 71% barium sulphate and 1% zinc oxide. It is used as an extending filler and white pigment. 

Lithopone is a mixture of zinc sulphide and barium sulphate in equimolecular proportions. It is used to establish a white base for coloured compounds. 

Yellow - chrome rutile yellow, cadmium sulphide/zinc sulphide... 

Aguilar, J. O. Gomez-Daza, O. Brito, L. A. Nair, M. T. S. Nair, P. K. 2005. Optical and mechanical characteristics of clear and solar control laminated glass using zinc sulphide and copper sulphide thin films. Surface Coatings Technol. 200 2557-2565. 

Flotation of Mixed Lead Zinc Sulphide Oxide and Oxide Lead and Zinc Ores... 

The beneficiation of mixed lead zinc sulphide oxide ores is a complex process and is dependent on gangue composition of the ore. There are two basic types of mixed sulphide oxide ores that have been extensively studied. These include (a) ores with dolomitic and... 

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