SRC Hydrometallurgy (LLC), Saint-Petersburg, Russia:

L. V. Chugaev, Principal Researcher, Candidate of Technical Sciences
M. A. Pleshkov, Principal Researcher, e-mail: pleshkov-m@gidrometall.ru
A. V. Markelov, Leading Researcher, e-mail: markelov-a@gidrometall.ru

Carbonaceous gold-bearing ores are an important variety of gold-bearing raw materials. During cyanidation of such ores and concentrates obtained from them, gold goes into a cyanide solution and is simultaneously sorbed on carbonaceous matter. This fact leads to significant gold loss with cyanide tailings. This phenomenon and the reason for the loss of gold associated with it are called preg-robbing. In this work, the object of research is the carbonaceous materials contained in the ores of the Verninskaya gold recovery plant (Bodaibo district of Irkutsk region), which is a structural unit of JSC “Polyus Verninsky” Polyus company. The factory uses a gravity-flotation flowsheet. The article proposes a method for the quantitative determination of sorbed state gold in the products of carbonaceous materials cyanidation. It was shown that most of the gold in the sorption feed (about 80%) dissolves in the first 1–2 hours of the process, after 4–6 hours of metal gold leaching, it remains in very small amount in the solid product. The main form of loss (not counting refractory finely dispersed gold) becomes gold sorbed on the natural carbonaceous matter. In the first reactor of the industrial cascade, gold sorbed onto the natural carbonaceous matter becomes the predominant form of gold in the cyanide material. It was found that during the further sorption cyanidation, the main process becomes the desorption of gold from the natural carbonaceous matter and its sorption on activated carbon; however, this process is slow, it forces to increase the duration of CIL to two or three days. It is shown that the reason for the low rate of transition of gold from the natural carbonaceous matter to a sorbent is the high preg-robbing in head reactors; the result of this is the need to increase the residence time of the pulp in tanks, that leads to increase in the number of tanks. There is a distribution of gold losses with sorption tailings (the last reactor): refractory gold is about 2.5 g/t (63%), gold sorbed on the natural carbonaceous matter about 1 g/t (32%) and elemental gold — less than 0.2 g/t (less than 5%).

1. Miller J. D., Wan R.-Y., Díaz X. Preg-Robbing Gold Ores. Advances in Gold Ore Processing. Amsterdam : Elsevier Science, 2016. pp. 885–907.
2. Stenebråten J. F., Johnson W. P., Brosnahan D. R. Characterization of Goldstrike ore carbonaceous material. Part 1: Chemical characteristics. Minerals and Metallurgical Processing. 1999. Vol. 16, No. 3. pp. 37–43.
3. Afenya P. M. Treatment of carbonaceous refractory gold ores. Minerals Engineering. 1991. Vol. 4, No. 7–11. pp. 1043–1055.
4. Meretukov M. A. Gold and natural carbonaceous matter. Moscow : Ruda i Metally, 2007. 112 p.
5. Stenebråten J. F., Johnson W. P., McMullen J. Characterization of Goldstrike ore carbonaceous material. Part 2: Physical characteristics. Minerals and Metallurgical Processing. 2000. Vol. 17. P. 7–15.
6. Advances in Gold ore processing: project development and operations. 2nd edition. Ed. by M. D. Adams. Amsterdam : Elsevier, 2016. 1020 p.
7. Chugaev L. V., Korzhenevskaya M. M. On the leaching of gold by sulfuric acid solutions. Izvestiya vuzov. Tsvetnaya Metallurgiya. 1972. No. 5. pp. 57–61.
8. Chugaev L. V. et al. The method of desorption of gold. Author certificate No. 552817 USSR. Published 1974.
9. La Brooy S. R. Practical aspects affecting gold adsorption and carbon fouling, innovations in gold & silver recovery. Randol International. 1992. Phase IV. Chapter 35. pp. 6543–6547.
10. La Brooy S. R., Wemyss P., Bowen J. M. Practical treatment options for carbonaceous preg-robbing gold ores. COM 2017. Vancouver, 27–30 August 2017.
11. Claflin J. K., Brooy S. R. J. L., Preedy D. Ausenco Carbon Reactivation Kiln Design Criteria. World Gold Conference 2013. Brisbane, 26–29 September 2013. pp. 401–410.
12. Claflin J. K. et al. Fast-payback reactivation of carbon from a flotation tails CIL circuit. World Gold Conference 2015. Gauteng, South Africa, 29 September – 1 October 2015. pp. 337–348.