Thermodynamics of arsenates, selenites and sulfates in the oxidation zone of sulfide ores: XII. Mineral equilibria in the Cd–Se–H₂O system at 25°C

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• 作者：M. V. Charykova ; A. V. Vishnevsky ; V. G. Krivovichev…
• 关键词：selenites ; cadmium selenite ; Eh ; pH diagrams ; thermogravimetry ; differential scanning calorimetry
• 刊名：Geology of Ore Deposits
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：58
• 期：8
• 页码：636-645
• 全文大小：
• 刊物主题：Mineral Resources;
• 出版者：Pleiades Publishing
• ISSN：1555-6476
• 卷排序：58

文摘

Understanding the mechanisms of cadmium and selenium behavior under near-surface conditions is very important for solving certain environmental problems. The principal aim of this study is physicochemical analysis of the formation conditions of synthetic cadmium selenite CdSeO₃ · H₂O and experimental investigation of its thermal stability and dehydration and dissociation mechanisms. The synthesis was performed by boiling-dry aqueous solutions of cadmium nitrate and sodium selenite. The obtained samples were identified with electron microprobe and powder X-ray diffraction. Complex thermal analysis (thermogravimetry and differential scanning calorimetry) have shown that CdSeO₃ · H₂O is dehydrated at 177–241°C in two stages, apparently corresponding to the formation of CdSeO₃ · 2/3H₂O. The Eh–pH diagrams were calculated using the Geochemist’s Workbench (GWB 9.0) software package. The Eh–pH diagrams have been calculated for the Cd–Se–Н₂О and Cd–Se–CO₂–H₂O systems for the average content of these elements in underground waters. The formation of cadmium selenite, CdSeO₃ · H₂O in the oxidation medium is quite possible. The existence of CdSeO₃ is possible at high temperature.