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Elastomers
Published in Ronald M. Scott, in the WORKPLACE, 2020
Talc is often used as a lubricant to prevent rubber from sticking to itself, or to facilitate its extrusion. Chemically, talc is hydrated magnesium silicate. Long-term inhalation of talc, even at the recommended TLV level of 1 mg/m3, produces increases in bronchitis, cough, and other respiratory problems due to obstruction or irritation of the respiratory tract. At higher levels, fibrosis can occur. This is especially serious if the talc contains traces of asbestos-type fibers, as some sources do.
Polymers
Published in Ronald Scott, of Industrial Hygiene, 2018
Talc is often used as a lubricant to prevent rubber from sticking to itself or to facilitate its extrusion. Chemically, talc is hydrated magnesium silicate. Long-term inhalation of talc, even at the recommended TLV level of 1.0 mg/m3 produces increases in bronchitis, cough, and other respiratory problems due to obstruction or irritation of the respiratory tract. At higher levels, fibrosis can occur. This is especially serious if the talc contains traces of asbestos-type fibers, as some sources do.
Industrial Minerals
Published in Earle A. Ripley, E. Robert Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, L. Moira Jackson, Environmental Effects of Mining, 2018
A. Ripley Earle, Robert E. Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, Earle A. Ripley, E. Robert Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, L. Moira Jackson
In 1992, Canadian production of these minerals came from five operations in Ontario, Québec, and Newfoundland (Bergeron and Andrews 1993). Talc is mined by underground methods when the orebodies are gently dipping or flat, and by open-pit methods for steeply dipping bodies. Production proceeds at a slow pace with both of these methods. The slippery nature of the talc mineral also poses some unusual problem: special slip-reducing tires and chains must be used on all machinery, and haulage slopes must not be steep.
The stimulus response of chitosan and its depression effect on talc flotation
Published in Mineral Processing and Extractive Metallurgy, 2018
Bo Feng, Jinxiu Peng, Wei Guo, Xianwen Zhu, Wanfu Huang
Talc, Mg3[Si4O10](OH)2, is a magnesium rich phyllosilicate mineral that occurs as a gangue component in many metal sulphide ore deposits around the world. Talc can report to flotation concentrates, thus reducing concentrate grade (Beattie et al. 2006; Lu et al. 2006). Since talc is a magnesium silicate mineral, large quantities of talc in flotation concentrates can cause problems during smelting as the presence of MgO will increase the slag melting point and increase the cost (Jenkins & Ralston 1998). Some polymer depressants, especially those that belong to the polysaccharide family, are used to reduce the natural floatability of talc in pentlandite and chalcopyrite flotation (Wang et al. 2005; Long et al. 2011; Lu et al. 2012). The most widely used are carboxymethyl cellulose (CMC) and Gum guar. CMC is a derivate of cellulose with carboxymethyl groups bound to the glucopyranose monomers. As CMC is an anionic polymer, many studies have demonstrated that CMC adsorption density onto minerals is strongly dependent on the pH and ionic strength of the solution (Morris et al. 2002; Khraisheh et al. 2005; Burdukova et al. 2008). Guar gum is chemically modified from natural gums. It has a strong depressant effect on talc and its effect is independent of pH (Rath et al. 1997; Wang et al. 2005). The adsorption of polysaccharide on talc is thought to be achieved by hydrogen bonding as well as chemical interaction (Laskowski et al. 2007).
Application of Knelson Concentrator for Beneficiation of Copper–Cobalt Ore Tailings
Published in Mineral Processing and Extractive Metallurgy Review, 2019
Christian Ndolwa Katwika, Meschac-Bill Kime, Pierre Ngoy Mwana Kalenga, Bienvenu Ilunga Mbuya, Tony Rukan Mwilen
The reduction of talc recovery in copper–cobalt flotation concentrates is very crucial. In fact, a high talc content into the concentrate lowers the copper–cobalt grades and causes problems in the smelters due to the resulting high MgO content (Pugh 1988; Klein et al. 2016; Kime and Kaniki 2017), forcing the smelter operators to impose penalties for the concentrators. Talc also causes the concentrate froth to be rigid and takes longer to break down. It also consumes a large amount of reagents in flotation. In the processing of high talc-containing copper–cobalt ore, talc is dealt with by pre-floating it together with quartz and other phyllosilicate minerals (muscovite, micas, chlorite, and serpentine) (Kime et al. 2015; Kime and Kaniki 2017). However, the big challenge comes from the fact that the milling of high talc-containing oxidized copper–cobalt ore is done at a coarser size (d80 ≈ 75–150 µm) to avoid overmilling the friable talc (Kime and Kaniki 2017). This is because talc is fairly hydrophobic; very fine talc (−38 μm) can adhere to air bubbles to such an extent that talc “crowds out” the copper–cobalt-bearing minerals on the bubbles and therefore reduces copper–cobalt concentrate grades and recoveries. The efficient liberation of minerals remains one of the major challenges in treating high talc-containing copper–cobalt ores. In addition, it has been observed that most of the recoverable copper and cobalt are contained in the −106 to + 38 µm range (Kime et al. 2015). Therefore, the trade-off coarse size of the flotation feed causes a significant amount of valuable minerals to be rejected to pre-flotation of phyllosilicate minerals and during the actual flotation.
A critical review of talc and ovarian cancer
Published in Journal of Toxicology and Environmental Health, Part B, 2020
Julie E. Goodman, Laura E. Kerper, Robyn L. Prueitt, Charlotte M. Marsh
Cosmetic-grade talc is used in baby powders, feminine hygiene products, antiperspirants, deodorants, creams, hair care products, lipsticks, shampoos, shaving products, wound ointments, foot powders, and sun care products (Fiume et al. 2015). Talc is also used in medical applications, including for pleurodesis, which is a medical procedure performed to treat malignant pleural effusions (Rosenman 2012). In 1976, cosmetic-grade talc specifications required that there be no detectable fibrous, asbestos minerals (Fiume et al. 2015).