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An Overview of Tungsten Toxicity
Published in Debasis Bagchi, Manashi Bagchi, Metal Toxicology Handbook, 2020
Ola Wasel, Jennifer L. Freeman
Tungsten (W) is a transition metal with an atomic number of 74, a molecular weight of 183.84, and belongs to Group VIB of the periodic table. Tungsten is present naturally in rocks and minerals. Tungsten is not present in a pure form, but it is naturally combined with other metals.1 The most common forms of tungsten that are used in industrial applications are wolframite and scheelite.1 Tungsten has the highest melting point and highest tensile strength at a temperature of over 1,665°C compared to all other metals.2 Tungsten has several oxidation states: 0, +2, +3, +4, +5, and +6. The physical and chemical properties of tungsten compounds vary based on the oxidation state (Table 24.1). Tungsten is used in the forms of tungsten carbide, metallic tungsten, tungsten chemicals, and tungsten alloy in many different applications (Figure 24.1).1,3
Enhanced flotation of Pb(II)-activated wolframite using a novel collector
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Jing Qi, Sheng Liu, Xianyang Qiu, Guangyi Liu
As a strategic key metal, tungsten has been widely used in national defense and modern manufacturing(Ilhan et al. 2013; Kupka and Rudolph 2018). Wolframite ((Fe, Mn)WO4) is a critical mineral resource for tungsten production (Habashi 2008; Martins 2014; Martins and Amarante 2013; Suri 2001). For the coarse particle wolframite, the gravity and magnetic separation are two main approaches to their enrichment and recovery (Meng, Feng and Ou 2017; Pandey et al. 2001; Sreenivas et al. 2004; Yang et al. 2016). While, wolframite is brittle, and to liberate it through crushing and grinding will produce plenty of fine particles, which have to be separated and enriched by froth flotation (Ai et al. 2017; Medvedev, Korshunov, and Khavskii 1995; Meng et al. 2015). Wolframite exhibits a certain hydrophilicity, to froth flotation, the first step is to hydrophobize it by collectors. Fatty acids, hydroxamic acids, and their derivatives are common collectors for wolframite flotation (Deng et al. 2015; Hu, Wang and Xu 1997; Meng et al. 2015; Yang 2018). Nowadays, the combination scheme of benzohydroxamic acid (BHA) collector and Pb(NO3)2 activator has been considered as a high-effective approach to float out of fine wolframite particles, which was successfully applied in Shizhuyuan Mine of China to replace the classical ‘‘Petrov’s process’’ (Han et al. 2017). The approach significantly increased the flotation recovery of tungsten in the wolframite concentrates to about 70%. Nevertheless, it still has enough space for promoting the recovery of fine wolframite particles.