Removal of Arsenic During Iron Extraction from Waste Copper Slag
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ORIGINAL ARTICLE
Removal of Arsenic During Iron Extraction from Waste Copper Slag Xin-yu Wan1 • Lu-kuo Hong2
•
Yuan-hong Qi1 • Jian-jun Gao1
Received: 13 December 2019 / Accepted: 28 July 2020 Ó The Indian Institute of Metals - IIM 2020
Abstract Substantial quantities of openly dumped slag contribute to the absence of recovery and utilization of valuable metals as well as potential environmental pollution to water and soil. Owing to the excessively high arsenic content present in iron extracted from copper smelting slag, we propose a new arsenic removal process in this paper. The results indicate that arsenic sulfides in copper smelting slag can be significantly removed at 1100 °C in an N2 atmosphere, leading to a 0.15% residual arsenic content. Furthermore, undecomposed arsenate in the slag can be reduced in an N2–CO atmosphere. During a coal-based direct reduction process, under optimal conditions, the removal efficiency of arsenic is relatively low. Subsequently, under optimal conditions, the arsenic content drops significantly from 0.18 to 0.080%. This new removal process engenders lower arsenic content in iron extracted from slag than the standards of pig iron and direct reduced iron in steelmaking. Keywords Copper slag Arsenic removal N2–CO atmosphere Coal-based direction Direct reduced iron (DRI)
& Lu-kuo Hong [email protected] Xin-yu Wan [email protected] 1
State Key Laboratory of Advanced Steel Process and Products, Central Iron and Steel Research Institute, Beijing 100081, China
2
College of Metallurgy and Energy, North China University of Science and Technology, Tangshan 063210, China
1 Introduction Copper smelting slag is an important by-product in the pyrometallurgical processing of copper. It has been estimated that the production of 1 ton of copper generates approximately 2.2 tons of copper smelting slag [1]. At least 17 million tons of slag is annually generated from copper production in China. According to the growth rate in recent years, it is predicted that copper smelting slag production will exceed 24 million tons by 2020 [2–4]. Disposing such substantial quantities of copper smelting slag poses environmental and spatial challenges. Consequently, the Chinese government has implemented policies that mandate mining and metallurgical companies to be responsible for reducing the volume of solid waste deposits, as well as enhancing its reutilization [5]. Copper smelting slag contains a high number of valuable metals, as lower comprehensive utilization rate; the vast majority of copper slag were open-air accumulated, occupying a substantial portion of land. In addition, the slag contains non-biodegradable matter such as arsenic, lead, and other highly toxic substances, which will go deep into the soil and flow into rivers during the accumulation process and accumulate in the biological body, leading to several diseases and health risks. The usage of copper slag to relieve the pressure on mineral resources and establish a profitable relationship between the economy and environment ha
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