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Bioremediation: Plants and Microbes for Restoration of Heavy Metal Contaminated Soils
Published in Jos T. Puthur, Om Parkash Dhankher, Bioenergy Crops, 2022
Harsh Kumar, Shumailah Ishtiyaq, Mayank Varun, Paulo J.C. Favas, Clement O. Ogunkunle, Manoj S. Paul
It is the primary metal used to make American pennies and die casting in the automobile sector. Some commonly used Zn compounds are zinc oxide (used in water colors or paints and as a modulator in the rubber industry), zinc chloride (used in deodorants), zinc sulfide (used for luminescent paints), zinc pyrithione (used as an anti-dandruff shampoo agent), and zinc carbonate (used as dietary supplements). Zinc metal is used in a tablet and is known for having antioxidant properties, which also defend against premature aging of the skin.
Feedstock Purification
Published in Martyn V. Twigg, Catalyst Handbook, 2018
The composition of the feedstock also affects the sulphur absorption profile. A very sharp profile is obtained when hydrogen is the process gas. The profile with methane is almost as sharp as with hydrogen, but high molecular weight hydrocarbons give a shallower profile. This is because of physical blocking of the capillaries, which causes an additional hindrance to the diffusion process. Carbon dioxide can also interfere with the absorption reaction. Zinc carbonate is stable at temperatures below about 160°C (dependent on the partial pressure of carbon dioxide). Hydrogen sulphide displaces carbon dioxide from zinc carbonate, but at low temperatures these are clearly competing reactions and absorption efficiency may be reduced.
Corrosion Resistance
Published in Frank Porter, Zinc Handbook, 1991
Zinc is attacked only slightly by pure air even if its moisture content is considerable. The hydroxide films formed (Schikorr, 1964) have a relatively minor protective effect. The zinc hydroxide reacts further with carbon dioxide in the atmosphere, forming a basic zinc carbonate. This film is very protective and is mainly responsible for the excellent resistance of zinc to ordinary atmospheres.
A Detailed study of Applying Gravity Separation to Lead and Zinc Carbonate Ore for Smithsonite Concentration Using DMC
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Ali Ebtedaei, Akbar Farzanegan
The detailed laboratory and plant tests on a low-grade lead and zinc ore showed that gravity separation using a DMC is a viable method to successfully separate zinc carbonate, smithsonite, from the gangue material. Furthermore, the authors used modeling and simulation approach to better characterize separation efficiency of the DMC operation and determine the optimal separating density. The results of sink-float evaluation by performing simple single-density tests indicate that gravity separation of valuable particles containing smithsonite mineral is feasible. In addition, the degree of liberation and the largest particle size resulting in a suitable percentage of the heavy mineral were found to be equal to 76% and 150 µm, respectively. The simulated results of the partition curve showed a separating density of 2.90 g·cm−3 as the best separating density. The simulated separation performance for 2.90 g·cm−3 as separating density is in close agreement with the single-density and multiple-densities laboratory sink-float tests.
Temperature and climate-induced fluctuations in froth flotation: an overview of different ore types
Published in Canadian Metallurgical Quarterly, 2023
Dzmitry Pashkevich, Ronghao Li, Kristian Waters
For base metal oxide ores, sulphidation with subsequent xanthate flotation is often employed [181]. As highlighted by Tyushkova et al., this process is also temperature dependent: large lead losses were registered when the process temperature decreased from 24°C to 15°C. Thus, conditioning at elevated temperatures was included in the flowsheet of the pre-production trials [182]. In another example, smithsonite (a zinc carbonate mineral) sulphidation was enhanced by heating the pulp from 20°C to 60°C, which resulted in a 30% flotation recovery increase [181].
Quartz and Hematite Activation by Zn, Ca and Mg Ions in the Cationic Flotation Route for Oxidized Zinc Ore
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Geraldo Magela Pereira Duarte, Rosa Malena Fernandes Lima
Zinc ore deposits are classified as sulfide or oxidized. This classification is due to the presence of the bearing mineral of this metal. Sulfide deposits contain sphalerite (ZnS) that can be found in association with other sulfides (galena and chalcopyrite) and with gangue minerals (pyrite, pyrrhotite, calcite, dolomite and quartz). The main zinc bearing minerals present in the oxidized deposits are silicates, hemimorphite, willemite, and the zinc carbonate smithsonite (Bulatovic 2007; Nuspl 2009).