Zinc-based products

Zinc compounds are generally colorless unless the other component, eg, chromate, is colored. The lack of color of most zinc compounds in visible light is a great advantage in that they do not color paint films, plastics, mbber, cosmetics, etc. However, when excited by various types of radiation and at various temperatures, zinc oxide, sulfide, selenide [1315-09-9], and related compounds exhibit luminescence, ie, they emit colored light (see Luminescent materials). Zinc-based phosphors can be produced in many colors, depending upon the added dopants. They are used in television tubes, luminescent glasses, and various specialty products. 

Ghromium complexes have been found to promote the co-polymerization of epoxides with G02- Recently, Darensbourg et al. have demonstrated that the chromium-salen complexes, remarkably more stable to the air and moisture than zinc-based co-polymerization catalysts, are effective catalysts for the co-polymerization of GHO with G02. " Under the condition of 5.9MPa GO2 pressure at 80 °G, complex 35a transforms GHO to the completely alternating co-polymer with a TON of 250 mol (mol of Zn) and a TOF of 10 mol (mol of Zn) h along with a small amount of eyelie earbonate production (Table 7). 

The electrolyte for zinc-based cells is always caustic alkali. Calcium hydroxide is sometimes added to remove zinc ions as insoluble CaZn2O3.5H20. A caustic alkali electrolyte is effectively buffered against OHion production by the oxygen cathode, so that OH concentration... 

After a short period of use in the average engine, changes start to occur. Initially, a loss of the zinc based antiwear/antioxidant additive ZDDP is observed by negative absorptions at 1000 cm 1 and 715 cm 1. Oxidative degradation of oil follows soon after and this is observed by positive absorptions, represented by carbonyl, hydroxy, nitro and C-O- species. The ER spectroscopy of lubricants can reflect additive depletion and the formation of oxidation products (Coates and Setti, 1984 Coates etal., 1984). 

Due to the wide use of cadmium-based products, cadmium is widely distributed in the environment. The cadmium content in soil and water has been increasing as a result of disposal of cadmium-contaminated waste and the use of cadmium-containing fertilizers (particularly on cereal crops). Commercial sludge, contaminated with cadmium, has been used to fertilize agricultural fields. Cadmium concentrations in urban air are quite low, because of regulation of industrial air emissions. Lead and zinc smelters and waste incineration account for the majority of cadmium present in ambient air. 

Barnes HM, Amburgey TL and Sanders MG (2004) Performance of zinc-based preservative systems in ground contact. Wood Design Focus, 14(2) 13-7 Barnes HM and Murphy RJ (1995) Wood Preservation the classics and the new age. Forest Products Journal, 45(9) 16-26... 

Synthetic motor oils are made of a synthesized hydrocarbon base oil of hydrogenated polydecene, decanoic acid esters, zinc alkyl dithiophosphate, and synthetic poly alpha olefins. Most synthetic oils also contain additives, detergents, and corrosion inhibitors as well as viscosity modifiers. It is believed that the first synthesized polymeric hydrocarbons were synthesized in 1877, yet it was not until 1929 that the commercial development of synthetic lubricants was undertaken. Because of the availability of commercial petroleum-based lubricants, these synthetic lubricants were ultimately unsuccessful. The advent of commercial jet travel spurred the development of the first commercially successful synthetic lubricant, Mobil 1, in 1975. This lubricant had superior resistance to thermal breakdown and lower friction properties than petroleum-based products. 

The presence of cadmium in the zinc-based end-product means that the product is not economically viable. 

Over the years, there have been searches on getting more environmentally benign, effective, and low-cost scavengers. This actually led to the organic compounds earlier mentioned. However, the search still continues until better and ideal scavengers are found. The common zinc-based compound has been modified into chelates and so forth, but for the fact that zinc is a heavy metal and thus environmentally unfriendly coupled with its adverse effects on mud rheology, the modified products have still not met the requirements of an ideal scavenger. 

Optimization starts with determining the zinc concentrate mix to be treated. This determination must be made considering all recoverable metal values and also the downstream metallurgical and operational constraints in the rest of the zinc and lead operations. Zinc concentrates with greater precious metal values typically also contain more iron and other impurities, resulting in a lower zinc metal production and an increased production of iron residues, whieh reduces available smelter capacity for other feed materials. Thus the optimum zinc concentrate feed mixture is based on all final products produced considering all downstream capacity implications. 

---