Hydrometallurgical process innovation

NSC Hydrometallurgical Pressure Oxidation of Combined Copper and Molybdenum Concentrates

“…The addition of or presence of NO 2 -instead of NO 3 -accelerates the formation of NO + . As shown in Table 1, the NO + /NO couple is capable of an extremely high redox potential [5]. So, NO + is readily formed from nitrous rather than nitric acid.…”

Semiconductor electrochemistry of coal pyrite. Final technical report, September 1990--September 1995

“…Pyrite is widely recognized as an electronic conductor and its oxidation has been described by the metal corrosion model for many years (Peters and Majima, 1968;Biegler and Swift, 1979;Peters, 1992). Some earlier studies (Springer, 1970;Biegler, 1975;Biegler and Swift, 1979) showed that n-and p-type pyrite exhibited very similar anodic and cathodic polarization curves under acidic conditions.…”

“…The conventional approach to pyrite electrochemistry is based on the metal electrode model (Peters and Majima, 1968;Biegler and Swift, 1979;Peters, 1992). Pyrite is treated as an electronic conductor and its oxidation is thought to proceed only through electron transfer.…”

“…There have been numerous studies on pyrite dissolution in the literature (see reviews: Hiskey and Schlitt, 1982;Lowson, 1982;Nordstrom, 1982, Peters, 1992. It is generally accepted that pyrite dissolution in acidic and oxidative conditions is an electrochemical process.…”

“…These include coal processing (Meyers, 1977;Ogunsola and Osseo-Asare, 1986;Drzymala and Wheelock, 1993;Liu et al, 1993), mineral processing (Woods, 1976;Chander et al, 1993;Witika and Dobias, 1995), hydrometallurgy (Peters, 1976(Peters, , 1986(Peters, , 1992Wadsworth, 1984;Osseo-Asare, 1992), environmental engineering (Aston, 1974;Ahmed and Giziewicz, 1992;Chander and Zhou, 1992;Osseo-Asare, 1993), geochemistry (Berner, 1970(Berner, ,1984Nordstrom, 1982;Morse et al, 1987;Schooner and Barnes, 1991a,b), and photovoltaic applications (Jaegermann and Tributsch, 1983;Ennaoui et al, 1986;Tributsch, 1986;Alonso-Vante and Tributsch, 1990;Ferrer and Sanchez, 1992). Pyrite oxidation or dissolution in aqueous solutions is of particular significance to the various engineering applications cited above.…”