High-purity copper recycled from smelter dust by sulfation roasting, water leaching and electrorefining
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ORIGINAL PAPER
High‑purity copper recycled from smelter dust by sulfation roasting, water leaching and electrorefining Jayati Priya1 · N. S. Randhawa2 · J. Hait2 · N. Bordoloi1 · J. N. Patel2 Received: 18 February 2020 / Accepted: 30 June 2020 © Springer Nature Switzerland AG 2020
Abstract Metal recycling is drawing high interest in the context declining natural resources and the future circular economy. Smelter dust from copper extraction plants contains copper (Cu), which is both an economic loss and a pollution issue. There is therefore a need for techniques to recover Cu from ultrafine dust. Here we tested sulfation roasting, water leaching and electrorefining to recover Cu. We studied this process by thermochemical simulation and thermogravimetry to optimize sulfation roasting parameters such as time, temperature and quantity of sulfuric acid. Results show that copper can be selectively recovered as 99.9% of pure copper. Moreover, we recycled chemicals by-products of the plant in the process. Our findings suggest that this process is upscalable and should decrease the environmental pollution by Cu. Keywords Copper smelter dust · Natural resource conservation · Recycling · Resource recovery technique · Sulfation roasting · Thermal treatment
Introduction Chalcopyrite, CuFeS2, is the major ore for the industrial production of the copper metal. The copper extraction process entails a pyro-cum-hydrometallurgical process consisting of smelting–converting–electrorefining methods (Schlesinger et al. 2011). Generally, the flash smelting of chalcopyrite concentrate generates a huge quantity of ultrafine dust (~ 50 kg/ton feed) collected in bag dust collectors and electrostatic precipitators. The dust generally contains 20–40%Cu, making it potentially valuable. Besides, the dust also hosts many impurities such as nickel, cobalt, bismuth, lead, iron, and arsenic (Sahu et al. 2012; Okanigbe et al. 2017; Kovyazin et al. 2019). Therefore, the recirculation of the dust back to the smelter is not recommended (Montenegro et al. 2008). The secure landfill or disposal of such dust material is also of great concern (Babula et al. 2008; Nagajyoti et al. 2010; Jarošíková et al. 2018). A recent study by Berasaluce et al. (2019) reveals carcinogenic health risk to * N. S. Randhawa [email protected] 1
Department of Environmental Science, Central University of Jharkhand, Ranchi 835204, India
Metal Extraction and Recycling Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007, India
2
people caused by soil and air pollution in adjoining area of a copper smelter. Therefore, a suitable alternative technique is necessary to recover copper values which may decrease the environmental burden due to the mining of natural resources. Besides, the success of a resource recovery technique also lies with its integration to established copper production circuits. Roasting is a method for the conversion of metal values into extractable form by heating at high temperature (Dimitrijevic et al. 2016; Lucheva et al. 2017). T
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