Recovery of valuable metals from mining and mineral processing waste

Abstract

Ammonia-thiosulfate-copper leaching, aided by a direct current electrochemical impact, is proposed to extract gold (Au), silver (Ag) and copper (Cu) from old flotation tailings mixed with waste rock. Over 80 % of Au available in the waste material and over 75 % of Cu and Ag were extracted into the pregnant leach solution (PLS) at room temperature. Electrowinning from that PLS recovered around 92 % of Au and Cu, and about 87 % of Ag in the cathode deposit that is suitable for further metallurgical refining. The results are better, compared to leaching in the same system but without electrochemical impact and at air addition. The proposed direct current aided method is promising and more environmentally friendly compared to cyanide and even to sodium thiosulfate leaching.

Modeling Indium Extraction, Supply, Price, Use and Recycling 1930–2200 Using the WORLD7 Model: Implication for the Imaginaries of Sustainable Europe 2050

“…Refining and recycling aspects were treated by several authors: Demarthe et al (1990), Alfatanzi andMoskalyk (2003), Alonso et al (2007), Johnson et al (2007), Parks et al (2009, Salhofer et al (2011), Zeng (2011, Ruan et al (2012), Zimmermann (2013), Reuter et al (2013), Zimmermann and Go ¨ssling-Reisemann (2014), Nassar et al (2015), Redlinger et al (2015), Gutowski et al (2016), Li et al (2020), andLin et al (2021). Panayotova and Panayatov (2013) gave examples of recycling rate for different processes, as well as indications of losses in different production stages of indium use. Many processes have low indium utilization, and low recovering rates.…”

“…Once material has been recovered and is chemically treated, recovery of indium from scrap can be from less than 50% to nearly 90% effective in the best cases. Indium is recovered together with germanium (Ge), arsenic (As) and cadmium (Cd) from zinc refining residuals such as roasting dust, anode slimes, slags (Panayotova & Panayatov, 2013). Yields for the indium recovery from zinc, copper and lead refining residuals are shown in Table 3.…”

“…The content in the ore varies from 1 to 100 ppm, depending on the deposit. Some silver deposits have as much as 3900 ppm of indium (Panayotova & Panayatov, 2013). On average, high grade zinc ore contains about 150 ppm of indium, or corresponding to 0.015% by weight (Werner et al, 2015).…”

“…For displays, indium tin oxide layers (ITO) are important. Earlier, this has been the main use of indium (Bleiwas, 2010;Panayotova & Panayatov, 2013), but this is changing toward photovoltaics. It is important for making semiconductors and microprocessors used for computers.…”

“…It is important for making semiconductors and microprocessors used for computers. Indium, in the form of SnO 2 -In 2 O 3 , is also used as an anode stabilizer (Panayotova & Panayatov, 2013). The demand from indium is expected to grow in the future.…”