Zinc materials

Indium is most frequently associated with zinc materials, and it is from these that most commercial indium is now obtained however, it is also found in iron, lead, and copper ores. 

Electrolytic and distillation processes are used to produce primary slab zinc at smelters from ores and concentrates, whereas redistillation is used to recover zinc from secondary zinc materials at both primary and secondary smelters (see Table 13) (64,65). In 1965, neady 60% of the primary slab zinc was manufactured by the distillation process. However, in 1975, electrolytic slab zinc became dominant and by 1996 its share increased to 78%. 

Anhydrous zinc chloride can be made from the reaction of the metal with chlorine or hydrogen chloride. It is usually made commercially by the reaction of aqueous hydrochloric acid with scrap zinc materials or roasted ore, ie, cmde zinc oxide. The solution is purified in various ways depending upon the impurities present. For example, iron and manganese precipitate after partial neutralization with zinc oxide or other alkah and oxidation with chlorine or sodium hypochlorite. Heavy metals are removed with zinc powder. The solution is concentrated by boiling, and hydrochloric acid is added to prevent the formation of basic chlorides. Zinc chloride is usually sold as a 47.4 wt % (sp gr 1.53) solution, but is also produced in soHd form by further evaporation until, upon cooling, an almost anhydrous salt crystallizes. The soHd is sometimes sold in fused form. 

Zinc was also already in use for protection in seawater in 1824 (see Section 1.3). In the beginning zinc material that was available from the hot-dip galvanizing industry was used but was less suitable because it became passive. Passivation does not occur with high-purity zinc. Super high grade zinc is the anode material with the least problems [5] and consists of 99.995% Zn and less than 0.0014% Fe without further additions. It is specified in Ref. 6 and permitted by the German Navy [7]. The most important properties of pure zinc are listed in Table 6-1. 

For the most part, the zinc materials recovered from secondary materials such as slab zinc, alloys, dusts, and compounds are comparable in quality to primary products. Zinc in brass is the principal form of secondary recovery, although secondary slab zinc has risen substantially over the last few years because it has been the principal zinc product of electric arc furnace (EAF) dust recycling. Impure zinc oxide products and zinc-bearing slags are sometimes used as trace element additives in fertilizers and animal feeds. About 10% of the domestic requirement for zinc is satisfied by old scrap. 

A second lifetime limitation is the zinc anode. In spite of the separator and cell designs, some zinc material is solubilized during the... 

To control EMI, ferrite beads (preferably of lossy nickel-zinc material) are sometimes placed in series with catch diodes (often slipped on to their leads), such as at the output diode of a typical off-line flyback. However, these beads must be very small, as they can have a significant effect on the efficiency of the power supply. 

Indium — (from the brilliant indigo line in its spectrum). In at. wt. 114.818(3) at. no. 49 m.p. 156.60°C b.p. 2072°C sp. gr. 7.31 (20°C) valence 1,2, or 3. Discovered by Reich and Richter, who later isolated the metal. Indium is most frequently associated with zinc materials, and it is from these that most commercial indium is now obtained however, it is also found in iron, lead, and copper ores. Until 1924, a gram or so constituted the world s supply of this element in isolated form. It is probably about as abundant as silver. About 4 million troy ounces of... 

Table IV summarizes the major constituents in the sulfide and oxide concentrates, and in the secondary materials processed at the zinc smelters and refineries. Sulfide concentrates represented 90% of all the feed materials of the 20 plants surveyed. The sulfide concentrates had higher iron contents, whereas the secondary zinc material had significantly higher cadmium and lead contents than the other feeds. Figure 2 illustrates the relationship between iron and zinc in the sulfide concentrates.

S.R Fugleberg and Poijarvi, Hydrometallurgical Treatment of Soluble Silicate-bearing Zinc Materials , US Pat.4.148.862.10 April 1979 (Outokumpu Oy). 

The ISP now accepts a wide range of secondary zinc materials including Waelz oxides, electrolytic zinc plant residues, galvanisers ashes and non-ferrous flue dusts. These materials are mainly either incorporated in the sinter plant feed or are hot briquetted and charged directly to the ISF. 

A pyrometallurgical process for the direct recovery of zinc from zinc concentrates and zinc/iron residues has been proposed and tested extensively by Noranda. The process consists of smelting bone-dry zinc containing materials (sulfide concentrates and secondary zinc/iron materials) in a molten iron oxysulfide bath to volatilize metallic zinc into a SOz-fiee ofTgas. Sulfiir contained in the feed materials is fixed as an iron oxysulfide matte for di sal. Thus, this process not only is capable of treating zinc sulfide concentrates and secondary zinc materials simultaneously, but also eliminates the need of sulfuric acid production. Detailed thermodynamic analysis and experimental test work are described in this paper. 

Possibility of smelting oxidic zinc materials in the proposed process... 

The policy of TR is continuously to explore all new possibilities to apply the MZP to any zinc material different than oxidized or carbonated zinc ores, and zinc secondaries. An example would be the treatment of zinc sulfides that are difficult to process via conventional roast-leach-electrowinning technology. 

Bambagioni V, Bianchini C, Filippi J, Oberhauserlal W, Marchionni A, Vizza F, Psaro R, Sordelli L, Foresti ML, Innocenti M (2009) Ethanol oxidation on electrocatalysts obtained by spontaneous deposition of palladium onto nickel-zinc materials. Chemsuschem 2(1) 99-112... 

Ponzevera, E., Quetel, C.R., Berglund, M., Taylor, P.D.P., Evans, P., Loss, R.D., and Fortunate, G. (2006) Mass discrimination during MC-ICPMS isotopic ratio measurements investigation by means of synthetic isotopic mixtures (IRMM-007 series) and application to the calibration of naturallike zinc materials (induding IRMM-... 

The hot sinter is screened and mixed with secondary zinc materials and coke pre-heated to 800 degrees centigrade. This mixture is fed into the top of the Imperial Smelting fiimace and the addition of preheated air reduces the lead and zinc oxides to metal. Zinc is produced as vapour, which is then condensed in a spray of molten lead. Liquid zinc separates on cooling and is either sold directly or refined. Lead formed in the furnace collects as bullion in the hearth at the bottom, along with molten slag, and can be separated and tapped. Precious metals and copper report in the lead bullion, which is then partially or completely refined on site. Overall recoveries of refined metals in the most modem ISP plants are 93 per cent or more for zinc and silver, about 70 per cent for copper and effectively 99-100 per cent for lead, if permanently recirculating metal is taken into account. 

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