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Heavy Metals
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Germanium (Ge) with an atomic number of 32, an atomic mass of 72.640, and a density of 5.32 g cm–3 is a silvery-white, brittle metalloid. Most of the germanium today is extracted from the zinc ore sphalerite. Germanite or copper iron germanium sulfide [CuS·FeS·GeS2] and argyrodite or silver germanium sulfide (Ag8GeS6) are the other important but rare ores containing germanium. Germanium is a semiconductor and was earlier used as a transistor after doping with arsenic and gallium. Currently, the major use of germanium is in camera and microscope lenses. Elemental germanium and germanium oxide are used in infrared spectroscopes. It is also used as an alloying agent (Encyclopaedia of Occupational Health and Safety 2012).
Future of photovoltaic materials with emphasis on resource availability, economic geology, criticality, and market size/growth
Published in CIM Journal, 2023
G. J. Simandl, S. Paradis, L. Simandl
Gallium belongs to the PV, critical, and specialty material categories (Figure 3). Its concentration in the continental crust is estimated at 18.6 ppm (Hu & Gao, 2008). Most of the Ga global yearly production (~90%) is obtained from bauxite ores as a co-product of Al manufacturing (Figure 6), as indicated by Butcher, Brown, and Gunn (2014). The geology of Ga was reviewed by Foley, Jaskula, Kimball, and Schulte (2017), and the compilation of Ga resources in bauxite deposits was provided by Schulte and Foley (2014). Some MVT Zn-Pb deposits (sensu lato; including the Irish-type), such as Lisheen, Ireland, contain 300–1,600 ppm Ga (Marsh et al., 2016). The Kipushi-type deposits (e.g., Tsumeb in Namibia; Söhnge & Houghton, 1964) and Kipushi Mine in the Zaire-Zambia copper belt, DRC, produced significant tonnages of Ga (Ivanhoe Mines, 2022). Similar to the MVT deposits, the Kipushi-type deposits are hosted by carbonate platform rocks and are associated with karst, solution collapse breccias, and related features (Foley et al., 2017; Hitzman, Kirkham, Broughton, Thorson, & Selley, 2005). They differ from MVT deposits mainly by their complex polymetallic signatures (Cu-Zn-Pb -Ag-As-Sb-Ge-Ga). Sphalerite is the main Ga-bearing mineral in MVT deposits, whereas gallite occurring as inclusions in renierite, germanite, and Cd-rich sphalerite is the main Ga carrier in Kipushi-type deposits (De Vos, Viaene, Moreau, Wautier, & Bartholomé, 1974). Depending on market conditions, gallium could also be conceivably recovered from the processing of sphalerite ores derived from traditional clastic-dominated sediment-hosted Zn-Pb deposits. For example, the Ga content of sphalerite concentrate from Red Dog, Alaska, is 26 ppm Ga (Marsh et al., 2016). To our knowledge, Ga is not currently recovered from this deposit. It is being recycled from scrap generated during the manufacturing of microelectronic components containing gallium arsenide (GaAs), gallium phosphide (GaP), and gallium nitride (GaN). It is expected that in the future, it will be increasingly recovered from CIGS-based thin-film PV products. Other potential sources of Ga (Figure 6) are coal fly ash, red mud (Al industry waste), and flue dust from furnaces producing elemental P (Lu et al., 2017).