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Post-Consumer Waste Production and Utilization
Published in Sehliselo Ndlovu, Geoffrey S. Simate, Elias Matinde, Waste Production and Utilization in the Metal Extraction Industry, 2017
Sehliselo Ndlovu, Geoffrey S. Simate, Elias Matinde
Zinc is a naturally occurring element found in the earth’s crust with a distribution ranging from 20 to 200 ppm (Goodwin, 1998). Typical soil concentrations range from 5 to 770 ppm of zinc, with an average concentration of about 60 ppm (Hogan, 2007). Oceans contain 30 ppb zinc, and air has 0.1–4.0 μg of zinc per cubic metre (Hogan, 2007). Despite being widely distributed, zinc metal is never found as a free element in nature because of its reactivity (Lloyd and Showak, 1984). However, zinc minerals are generally associated with other metal minerals, the most common associations in ores being zinc–lead, lead–zinc, zinc–copper, copper–zinc, zinc–silver or zinc only (BCS Inc., 2002). Zinc is also combined with sulphur in a mineral called zinc blende or sphalerite (ZnS) (BCS Inc., 2002), which provides about 90% of zinc production (Goodwin, 1998; BCS Inc., 2002; Roney et al., 2005). Sphalerite contains 60%–62% Zn, and the largest deposits of sphalerite are found in Australia, Canada and the United States (Hogan, 2007). Other zinc-containing minerals (non-sulphide zinc) include hemimorphite, hydrozincite, calamine, franklinite, smithsonite, willemite and zincite (BCS Inc., 2002; Boni, 2003; Boni and Large, 2003).
James Smithson on the Calamines: Chemical Combination in Crystals
Published in Ambix, 2018
In recognition of Smithson’s contribution, the non-hydrous carbonate of zinc was subsequently named “smithsonite.” The name was proposed in 1832 by Haüy’s student and successor in the chair of mineralogy and geology at the Faculté des sciences in Paris, François Sulpice Beudant (1787–1850).64 The silicated zinc compound Smithson studied (the “electric” calamine) has since become known as “hemimorphite.” The name was proposed by the German mineralogist Adolph Kenngott (1818–1897) in 1853. Kenngott acknowledged that the property of hemimorphism was shared by other minerals, but he believed that using the name to signify this particular substance might encourage the identification of other stones with similar crystallography. To describe Smithson’s hydrated zinc carbonate Kenngott proposed the name “hydrozincite,” which is still used by mineralogists.65
Atmospheric corrosion of Zn–Al coatings in a simulated automotive environment*
Published in Surface Engineering, 2018
Xian Zhang, Inger Odnevall Wallinder, Christofer Leygraf
Extensive investigations have been reported in the scientific literature on atmospheric corrosion of zinc at natural weathering conditions [13–16]. A general corrosion product formation and evolution scheme on zinc was established by Odnevall and Leygraf [17]. In any humid-containing atmosphere, a thin layer of amorphous hydroxycarbonate (Zn5(OH)6CO3, hydrozincite) quickly forms. This phase often gradually develops into its crystalline form in humid, low polluted environments. In the presence of chlorides in the atmosphere, zinc hydroxychloride (Zn5(OH)8Cl2·H2O, simonkolleite) is locally formed. If sulphate is present, this phase eventually evolves into a sodium zinc hydroxychlorosulphate (NaZn4Cl(OH)6SO4·6H2O, gordaite). Atmospheric corrosion processes of zinc at laboratory-simulated conditions have been extensively studied in the literature [18,19], revealing Zn5(OH)8Cl2·H2O as the main corrosion product formed at chloride-rich conditions [20].
Mineral characterisation of the non-sulphide Zn mineralisation of the Florida Canyon deposit, Bongará District, Northern Peru
Published in Applied Earth Science, 2019
Saulo Batista de Oliveira, Caetano Juliani, Lena Virgínia Soares Monteiro
Takahashi (1960) determined experimentally the stability fields of the common paragenesis of supergene Zn deposits (smithsonite, hemimorphite, and hydrozincite) simulating supergene conditions when the minerals were contacted with meteoric water (approximately 25°C and 1 atm pressure). The conversion of smithsonite to hydrozincite [Zn5(CO3)2(OH)6] is controlled by pH and CO2 partial pressure. Takahashi (1960) shows that in arid climate conditions, hydrozincite predominates over smithsonite on the surface, but the relationship reverses with depth.