Zinc-lead concentrate

The zinc concentrate is first roasted in a fluid-bed roaster to convert the zinc sulfide to the oxide and a small amount of sulfate. Normally, roasting is carried out with an excess of oxygen below 1000°C so that comparatively htde cadmium is eliminated from the calcined material in this operation (3). Since the advent of the Imperial Smelting Zinc Furnace, the preliminary roasting processes for zinc and zinc—lead concentrates result in cadmium recovery as precipitates from solution or as cadmium—lead fame, respectively, as shown in Figure 1. 

Magmont Iron, Mo. Cominco American Incorporated lead—zinc ore, concentrated ... 

Sulfide ores usually contain small amounts of mercury, arsenic, selenium, and tellurium, and these impurities volatilize during the ore treatment. All the volatilized impurities, with the exception of mercury, are collected in the dust recovery systems. On account of its being present in low concentrations, mercury is not removed by such a system and passes out with the exit gases. The problem of mercury contamination is particularly pertinent to zinc plants since the sulfidic ores of zinc contain traces of mercury (20-300 ppm). The mercury traces in zinc sulfide concentrates volatilize during roasting and contaminate the sulfuric acid that is made from the sulfur dioxide produced. If the acid is then used to produce phosphatic fertilizers, this may lead to mercury entering the food chain as a contaminant. Several processes have been developed for the removal of mercury, but these are not yet widely adopted. 

Chiaradia M, Gulson BL, MacDonald K. 1997. Contamination of houses by workers occupationally exposed in a lead-zinc-copper mine and impact on blood lead concentrations in the families. Occup Environ Med 54(2) 117-124. 

Froom P, Kristal-Boneh E, Benbassat J, et al. 1998. Predictive values of determinations of zinc protoporphyrin for increase blood lead concentrations. Clin Chem 44 1283-1288. 

Proximity to the smokestacks of metal smelters is positively associated with increased levels of lead in the hair (manes) of horses and in tissues of small mammals, and is consistent with the results of soil and vegetation analyses (USEPA 1972). Lead concentrations were comparatively high in the hair of older or chronically impaired horses (USEPA 1972). However, tissues of white-tailed deer (Odocoileus virginianus) collected near a zinc smelter did not contain elevated levels of lead (Sileo and Beyer 1985). Among small mammals near a metal smelter, blood ALAD activity was reduced in the white-footed mouse but normal in others, e.g., the short-tailed shrew (Beyer et al. 1985). The interaction effects of lead components in smelter emissions with other components, such as zinc, cadmium, and arsenic, are unresolved (USEPA 1972) and warrant additional research. 

Starlings from pristine area in Poland were exposed in cages for 8 days near a zinc smelter Tissue lead concentrations were 3 to 12 times higher after 8 days stomach content lead levels increased from 2 mg/kg DW to 532, and feces increased from 0.4 to 154 mg Pb/kg DW 56... 

In the case of a copper-zinc and copper-lead-zinc ore, gold collects in the copper concentrate. During the treatment of lead-zinc ores, the gold tends to report to the lead concentrate. Information regarding gold recovery from base metal ores is sparse. 

Peters (5) Has reviewed the leaching of copper, nickel, zinc, lead and molybdenum concentrates in terms of the thermodynamic stability of the sulfide minerals of these metals. Process developments associated with the most favorable decomposition paths are considered. 

For the flotation separation of the mixtures of galena-sphalerite, using DDTC as a collector and lime as a pH modifier, the mixture is ground in Fe medium and the potential is made at 90 mV. The lead concentrate assayed of 74.4% Pb and zinc concentrate assayed of 57.51% Zn can be obtained. The recovery of lead and zinc are, respectively, 88.14% and 95.3%. The flotation separation of a mixture of sphalerite mid pyrite is conducted at pH = 12 modified by lime and using butyl xanthate as a collector. The mixture is ground in Fe medium and the potential is 150 mV. The zinc concentrate assayed of 58.1% Zn and sulphur concentrate assayed of 48.56% S can be obtained. The recovery of zinc and sulphur are, respectively, 92.1% and 59.83%. 

The ferromanganese nodules sho w a marked increase (up to 10 - 100 times) in manganese, cobalt, nickel, zinc, and copper concentrations (Guliy 2004). In contrast, the U and Th contents in the nodules show a weak increase (less than 2 times). Manganese, iron, cobalt, nickel, zinc, lead, and copper in the nodules are subdivided on the basis of character of their correlation into two main groups Mn, Ni, Zn, Cu and Fe, Pb, and Co. However, our results do not show any strong correlation between these elements and U, Th, and Ra. 

Heavy metals such as copper, zinc, lead, nickel, silver, arsenic, selenium, cadmium and chromium may originate from many sources within a rehnery and may, in specihc cases, require end-of-pipe treatment. Some agencies have set discharge limits that are beyond the capability of common metals removal processes such as lime precipitahon and clarihcation to achieve. Other treatment processes such as iron coprecipitation and adsorption, ion exchange, and reverse osmosis may be required to achieve these low effluent concentrations [52]. 

If the low rade ore is a zinc mineral, then zinc concentrate obtained from the flotation process is calcined and leached with water to remove zinc. Silver and lead are left in leach residues. Residues are treated like lead concentrates and fed into lead smelters. Silver is recovered from this lead concentrate by various processes described above. 

Results For the St. Louis data, the target transformation analysis results for the fine fraction without July Uth and 5th are given in table 6. The presence of a motor vehicle source, a sulfur source, a soil or flyash source, a titanium source, and a zinc source are indicated. The sulfur, titanium and zinc factors were determined from the simple initial test vectors for those elements. The concentration of sulfur was not related to any other elements and represents a secondary sulfate aerosol resulting from the conversion of primary sulfur oxide emissions. Titanium was found to be associated with sulfur, calcium, iron, and barium. Rheingrover ( jt) identified the source of titanium as a paint-pigment factory located to the south of station 112. The zinc factor, associated with the elements chlorine, potassium, iron and lead, is attributed to refuse incinerator emissions. This factor could also represent particles from zinc and/or lead smelters, though a high chlorine concentration is usually associated with particles from refuse incinerators ( ). The sulfur concentration in the refined sulfate factor is consistent with that of ammonium sulfate. The calculated lead concentration in the motor vehicle factor of ten percent and a lead to bromine ratio of about 0.28 are typical of values reported in the literature (25). The concentration of lead in... 

After dipping strips of zinc into concentrated solutions of manganese salts, they scraped off a deposit containing zinc, lead, cadmium, nickel, and cobalt. After complete removal of these heavy metals by precipitation as the sulfides, they found no evidence of element 43, but thought they found the X-ray lines of number 75 ( 42). When Dr. Druce took his dwi-manganese preparation to the Charles University in Prague for polaro-graphic examination, the Czechoslovakian chemists confirmed his conclusions. 

Cadmium occurs primarily as sulfide minerals in zinc, lead—zinc, and copper—lead—zinc ores. Beneficiation of these minerals, usually by flotation (qv) or heavy-media separation, yields concentrates which are then processed for the recovery of the contained metal values. Cadmium follows the zinc with which it is so closely associated (see Zinc and zinc alloys see also Copper Lead). 

One of the most interesting aspects of molten salt chemistry is the readiness with which metals dissolve. FOr example, the alkali halides dissolve large amounts of the corresponding alkali metal, and some systems (e.g., cesium in cesium halides] are completely miscible at all temperatures above the melting point. On the other hand, the halides of zinc, lead, and tin dissolve such small amounts of the corresponding free metal that special analytical techniques must be devised in order to estimate the concentration accurately. 

---