Institute of Mining, Far East Branch, Russian Academy of Sciences, Khabarovsk, Russia:

A. G. Sekisov, Chief Researcher, Doctor of Engineering Sciences, sekisovag@mail.ru

A. V. Rasskazova, Senior Researcher, Candidate of Engineering Sciences

Far East Geological Institute, Far East Branch, Russian Academy of Sciences, Khabarovsk, Russia:
V. V. Ivanov, Leading Researcher, Candidate of Geologo-Mineralogical Sciences

Amur Minerals, Khabarovsk, Russia:
E. K. Ignatyev, Deputy CEO in Geology

Geochemical features of ore in the oxidation zone of the Malmyzh copper–gold deposit located in the Nanai Region of the Khabarovsk Territory are characterized in the article. Diorite porphyry ores of the Malmyzh oxidation zone feature supergene transformation, are metasomatized to a various extent, and have low copper content from the viewpoint of commercial production (less than 0.3%) and the increased content of gold (0.1–1.2 g/t). The analysis of the methods applied for the processing of this type ore is carried out. Heap leaching is the most efficient processing method for such ore. Based on the actual exploration data, the conclusion is drawn that during operational exploration within the oxidation zone, it is expedient to carry out drilling in the sites of standard-quality ore with a view to implementing heap leaching at the minimum content of commercial gold. Later on, selective extraction of these sites will ensure their profitable processing by the method of heap leaching. The float-and-sink analysis and moisture content data of oxidized ore crushing product allow a conclusion on the need of preliminary (before piling) separation of fine size grades and their pelletizing in active solutions. According to earlier studies, gold in primary ore occurs in the form of tellurides, natural alloys with copper and silver, including copper electrum, as well as in silicates, supposedly, in clusters. The results of preliminary laboratory analyses and geotechnical investigations of the Malmyzh oxidized ore using a number of chemical reagents in the mode of agitation leaching of gold from milled samples are presented. The first reagent scheme of gold leaching included ore pretreatment in activated peroxide–carbonaceous solution and subsequent leaching of gold by ammonia–cyanide solution. Activation of solutions was performed in electrochemical and photochemical reactors. The second scheme provided preparation of ore by the active peroxide–sulfuric solutions with subsequent gold leaching by solutions with cyanide and chloride reagents. It is found that the highest rate of gold recovery to pregnant solution (94%) is provided by the chloride scheme with the peroxide–sulfuric pretreatment of ore. The tests of gold leaching from crushed (-10 mm) oxidized copper–gold ore proved advantages of the peroxide–sulfuric preparation of ore with the subsequent chloride leaching (gold recovery reached 82%).
The authors are grateful to N. M. Litvinova, T. G. Konareva and K. V. Prokhorov, Institute of Mining, FEB RAS, for the participation in the experimentation.

The study was supported by the Presidium of the Far East Branch of the Russian Academy of Sciences in the framework of the Project No. 18–2-015: Porphyry Copper–Gold Mineralization in the Far East of Russia–Geodynamic Situation Indicators, Ore Zone Magmatism and Mineralogical–Geochemical Features of Ore-Magmatic Systems with a View to Predicting, Exploring, Appraising and Mining Such Type Deposits.

1. Bobadilla-Fazzini R. A., Pérez A., Gautier V., Jordan H., Parada P. Primary copper sulfides bioleaching vs. chloride leaching: Advantages and drawbacks. Hydrometallurgy. 2017. Vol. 168. pp. 26–31.
2. Trubilov V. S., Klepikov A. S. Copper-containing dumps as a prospective source of copper obtaining. Tsvetnye Metally. 2014. No. 11. pp. 31–36.
3. Breuer P. L., Dai X. , Jeffrey M. I. Leaching of gold and copper minerals in cyanide deficient copper solutions. Hydrometallurgy. 2005. Vol. 78, Iss. 3-4. pp. 156–165.
4. Alonso-González O., Nava-Alonso F., Uribe-Salas A. Copper removal from cyanide solutions by acidification. Minerals Engineering. 2009. Vol. 22, Iss. 4. pp. 324–329.
5. Alonso-González O., Nava-Alonso F., Jimenez-Velasco C., Uribe-Salas A. Copper cyanide removal by precipitation with quaternary ammonium salts. Minerals Engineering. 2013. Vol. 42. pp. 43–49.
6. Gönen N., Kabasakal O. S., Özdil G. Recovery of cyanide in gold leach waste solution by volatilization and absorption. Journal of Hazardous Materials. 2004. Vol. 113, Iss. 1-3. pp. 231–236.
7. Xie F., Dreisinger D. Recovery of copper cyanide from waste cyanide solution by LIX 7950. Minerals Engineering. 2009. Vol. 22, Iss. 2. pp. 190–195.
8. Watling H. R. Chalcopyrite hydrometallurgy at atmospheric pressure: 1. Review of acidic sulfate, sulfate–chloride and sulfate–nitrate process options. Hydrometallurgy. 2013. Vol. 140. pp. 163–180.
9. Smith S. R., Zhou C., Baron J. Y., Choi Y., Lipkowski J. Elucidating the interfacial interactions of copper and ammonia with the sulfur passive layer during thiosulfate mediated gold leaching. Electrochimica Acta. 2016. Vol. 210. pp. 925–934.
10. Bas A. D., Koc E., Yazici E. Y., Deveci H. Treatment of copper-rich gold ore by cyanide leaching, ammonia pretreatment and ammoniacal cyanide leaching. Transactions of Nonferrous Metals Society of China. 2015. Vol. 25, Iss. 2. pp. 597–607.
11. Lodeyshchikov V. M., Khmelnitskaya O. D., Voyloshnikov G. I. Ammonical cyanidat ion copper goldbearing ores. Tsvetnye Metally. 2010. No. 8. pp. 23–26.
12. Strizhko L. S., Bobozoda Sh., Boboev I. R., Berger B. R. Extraction of gold from gold-copper raw materials. Tsvetnye Metally. 2014. No. 6. pp. 41–43.
13. Strizhko L. S. Gold and Silver Metallurgy. Moscow : MISIS, 2001. 336 p.
14. Porvali A., Rintala L., Aromaa J., Kaartinen T., Forsen O., Lundstrom M. Thiosulfate-copper-ammonia leaching of pure gold and pressure oxidized concentrate. Physicochemical Problems of Mineral Processing. 2017. Vol. 53, No. 2. pp. 1079–1091.
15. Boboev I. R., Bobozoda Sh., Strizhko L. S. Leaching Stubborn Oxidized Gold Ores That Contain Copper. Metallurgist. 2016. Vol. 59, No. 9–10. pp. 959–963.
16. Ivanov V. V., Kononov V. V., Ignatiev E. K. Mineralogical and geochemical features of mineralization in metasomatic deposits of the Malmyzh copper–gold belt (Low Amur Region). All-Russian Conference Proceedings: Tectonics, Deep Structure and Minerageny in Eastern Asia – VIII Kosygin’s Lectures. Khabarovsk, 2013. pp. 258–261.
17. A. G. Sekisov, A. V. Rasskazova. Method of leaching gold from refractory ores. Patent RF, No. 2647961. Applied: 09.06.2017. Published: 21.03.2018. Bulletin No. 9.