Central Scientific-Research Geological Prospecting Institute of Non-Ferrous and Noble Metals, Moscow, Russia:

G. V. Sedelnikova, Deputy Director, e-mail: gsedelnikova@mail.ru

All-Russian Scientific-Research Institute of Mineral Raw Materials named after N. M. Fedorovsky, Moscow, Russia:

A. V. Kurkov, Deputy General Director

Leading Scientific-Research Institute of Chemical Technologies, Moscow, Russia:
K. M. Smirnov, Head of Department “Complex Processing of Mineral Raw Materials”

The paper presents the review of the main results of Russian scientific researches devoted to the process of autoclave processing of refractory and double refractory gold-bearing sulfide concentrates; technological routes and projects published in specialized editions in 2011–2015 and proposed for putting into practice are observed. Different methods allowing to decrease gold wastes in preg robbing are considered. Behavior of sulfides and gold during autoclave oxidation of concentrates is described using thermodynamical models, and possibility of metallic gold dissolution with anion [AuCl₄]^– forming and its adsorption on organic carbon particles is shown. Flotation or gravitation methods are used to remove carbon from concentrates before autoclave oxidation. In order to decrease gold wastes during autoclave preg robbing, the following methods can be provided: concentrate washing by water containing no chlorides until its charging in autoclave; lowering of oxidizing-reducing potential inside autoclave during oxidation via limestone adding in oxidizing pulp; conditioning of autoclave unloading etc. Negative role of some pseudo-halogenides and their complexes charging in the autoclave with acute water is displayed, as well as possibilities of its cleaning using reversed osmosis units. Influence of such factors as oxygen pressure, temperature, concentrate crushing and duration of autoclave oxidation on gold extraction during consequent cyanidation is examined. The examples of combined technological routes for processing of gold-sulfide concentrates are presented. They are based on combination of bio-oxidation, autoclave oxidation, hydrometallurgy and pyrometallurgy.

1. Shneerson Ya. M., Naboychenko S. S. Tendentsiya razvitiya avtoklavnoy gidrometallurgii tsvetnykh metallov (Trend of development of autoclave hydrometallurgy of non-ferrous metals). Tsvetnye Metally = Non-ferrous metals. 2011. No. 3. pp. 15–20.
2. Zakharov B. A., Meretukov M. A. Zoloto: upornye rudy (Gold: refractory ores). Moscow : “Ore and Metals” Publishing House, 2013. 452 p.
3. Meretukov M. A., Sanakulov K. S., Zimin A. V., Arustamyan M. A. Zoloto: khimiya dlya metallurgov i obogatiteley (Gold: chemistry for metallurgists and concentrators). Moscow : “Ore and Metals” Publishing House, 2014. 412 p.
4. Turysbekova G. S., Meretukov M. A., Bektay E. K. Zoloto: innovatsii v khimii i metallurgii (Gold: innovations in chemistry and metallurgy). Almaty : Publishing House of Kazakh National Research Technical University after K. I. Satpaev, 2015. 632 p.
5. Chugaev L. V., Shneerson Ya. M., Lapin A. Yu. Avtoklavnye tekhnologii v zolotoizvlekatelnoy promyshlennosti (Autoclave technologies in gold extraction industry). Zoloto i tekhnologii = Gold and Technologies. 2014. No. 3 (25). pp. 36–40.
6. Shneerson Ya. M., Fedorov V. K., Lapin A. Yu., Klementev M. V., Kropachev G. A. Ispolzovanie tekhnologii avtoklavnogo okisleniya pri pererabotke zolotosoderzhashchikh kontsentratov v Rossiyskoy Federatsii (Using the technology of pressure oxidation during the production of gold-bearing concentrates in Russian Federation). Zoloto i tekhnologii = Gold and Technologies. 2013. No. 4 (22). pp. 38–43.
7. Sedelnikova G. V. Praktika izvlecheniya zolota iz upornykh rud (Practice of gold extraction from refractory ores). Zolotodobyvayushchaya promysh lennost = Gold mining industry. 2014. No. 4 (64). pp. 25–28.
8. Sedelnikova G. V. Praktika izvlecheniya zolota iz upornykh rud (Practice of gold extraction from refractory ores). Zolotodobyvayushchaya promyshlennost = Gold mining industry. 2014. No. 5 (65). pp. 41–46.
9. Zaytsev P. V., Shneerson Ya. M., Lapin L. V., Chugaev L. V., Klementev M. V., Pleshkov M. A., Fomenko I. V., Bakhvalov S. S. Razrabotka tekhnologii pererabotki upornykh zolotosoderzhashchikh kontsentratov na Pokrovskom avtoklavno-gidrometallurgicheskom komplekse (Process Development for Refractory Gold Concentrates Treatment on Pokrovsky POX Hub). Zhurnal Sibirskogo federalnogo universiteta. Tekhnika i tekhnologii = Journal of Siberian Federal University. Engineering and Technologies. 2014. Vol. 7, No. 5. pp. 533–543.

10. Aleksandrova T. N., Tsyplakov V. N., Romashev A. O., Semenikhin D. N. Udalenie sorbtsionno-aktivnykh uglerodistykh veshchestv iz upornykh zolotosulfidnykh rud i kontsentratov mestorozhdeniya Mayskoe (Removal of sorption-active carboniferous components from difficultly-treated gold sulfide ores and concentrates of the Mayskoye deposit). Obogashchenie Rud = Mineral processing. 2015. No. 4. pp. 3–7. DOI: http://dx.doi.org/10.17580/or.2015.04.01
11. Markelov A., Shneerson Y., Boginskaya A., Chugaev L. Mathematical modeling of sulfide concentrates pressure oxidation using laboratory kinetics. Proceedings of Alta 2014 Gold Conference. Perth, WA, Australia, 2014. pp. 235–246.
12. Boginskaya A. S., Markelov A. V., Shneerson Ya. M., Petrov G. V. Primenenie metoda matematicheskogo modelirovaniya dlya rascheta protsessa avtoklavnogo okisleniya upornogo sulfidnogo zolotosoderzhashchego flotokontsentrata (Application of mathematical modeling for calculation of autoclave leaching process of refractory sulfide auriferous flotation concentrate). Fundamentalnye issledovaniya = Fundamental research. 2014. Vol. 3, No. 4. pp. 706–710.
13. Shneerson Ya. M., Markelov A. V., Chugaev L. V., Kabisova A. S. Kinetika avtoklavnogo okisleniya upornykh zolotosoderzhashchikh sulfidnykh kontsentratov (Kinetics of autoclave oxidation of refractory gold-containing sulfide concentrates). Tsvetnye Metally = Non-ferrous metals. 2015. No. 1. pp. 35–39.
14. Fomenko I. V., Pleshkov M. A., Chugaev L. V., Shneerson Ya. M. Termodinamicheskoe opisanie povedeniya zolota pri avtoklavnom okislenii sulfidnykh kontsentratov (Thermodynamic description of gold behavior during the pressure oxidation of sulfide concentrates). Tsvetnye metally — 2013 : sbornik nauchnykh statey (Non-ferrous metals – 2013 : collection of scientific proceedings). Krasnoyarsk : Verso, 2013. pp. 381–386.
15. Fomenko I. V., Pleshkov M. A., Chugaev L. V., Shneerson Ya. M. Mekhanizm formirovaniya poter zolota pri avtoklavnom okislenii i posleduyushchem tsianirovanii kontsentratov dvoynoy upornosti (Mechanism of formation of gold losses during the pressure oxidation and further cyanidation of double-refractory concentrates). Tsvetnye metally – 2012 : sbornik nauchnykh statey (Non-ferrous metals – 2012 : collection of scientific proceedings). Krasnoyarsk : Verso, 2012. pp. 598–604.
16. Zaytsev P. V., Fomenko I. V., Shneerson Y. M., Chugaev L. V., Pleshkov M. A. Specifics of double refractory gold concentrates pressure oxidation in the presence of chlorides. Proceedings of the 7th International Symposium of Hydrometallurgy 2014. Victoria, BC, 2014. pp. 501–514.
17. Tsyplakov V., Kovalev V., Vorob’ev-Desyatovskii N., Ter-Oganesiants A., Kaplan S. Key ways to suppress preg-robbing in autoclave treatment of highly refractory gold concentrates. Proceedings of XXVI International Mineral Processing Congress “IMPC-2012”. New Dehli, 24–28 september 2012. pp. 5543–5550.
18. Polezhaev S. Yu., Pleshkov M. A., Fomenko I. V., Chugaev L. V., Shneerson Ya. M., Klementev M. V. Vliyanie glubiny okisleniya sulfidov na izvlechenie zolota iz upornykh kontsentratov (Influence of the depth of sulfide oxidation on gold extraction from refractory concentrates). Tsvetnye metally – 2013 : sbornik nauchnykh statey (Non-ferrous metals – 2013 : collection of scientific proceedings). Krasnoyarsk : Verso, 2013. pp. 393–397.
19. Zaytsev P. V., Lyakh S. I., Shneerson Ya. M., Lapin A. Yu., Chugaev L. V., Klementev M. V., Pleshkov M. A., Fomenko I. V. Razrabotka gidrometallurgicheskoy tekhnologii pererabotki zolotosoderzhashchikh rud Malomyr i Pioner (Development of hydrometallurgical technology of processing of gold-bearing ores Malomyr and Pioner). Tsvetnye metally – 2013 : sbornik nauchnykh statey (Non-ferrous metals – 2013 : collection of scientific proceedings). Krasnoyarsk : Verso, 2013. pp. 403–409.
20. Axenov B., Vorob’ev-Desyatovskii N., Kaplan S., Kovalev V. et al. Cyanide preg-robbing effect is a problem, which can arise during autoclave processing of double refractory gold ores. Proceedings of XXVII International Mineral Processing Congress. Santiago, Chile. 2014. Part 19. pp. 244–251.
21. Zolotarev F. D., Aleksandrova T. N., Kaplan S. F. Vliyanie dobavki Cl^– i CN^– v protsesse avtoklavnogo izvlecheniya zolota iz upornogo syrya (Influence of Cl^– and CN^– additive in the process of autoclave extraction of gold from refractory raw materials). Materialy mezhdunarodnogo soveshchaniya “Plaksinskie chteniya – 2015” (Materials of international meeting “Plaksin readings – 2015”). Irkutsk, 2015. pp. 329–330.
22. Fedyukevich V. A., Kubyshkin S. A., Blokhin A. A., Sukharzhevskiy S. M., Vorobev-Desyatovskiy N. V. Ispolzovanie ionoobmennykh smol dlya borby s yavleniem preg-robbinga zolota v protsesse tsianidnogo vyshchelachivaniya (Use of ion-exchange resins to deal with the effect of preg-robbing of gold in the course of cyanide leaching). Zhurnal prikladnoy khimii = Russian Journal of Applied Chemistry. 2015. Vol. 88, No. 2. pp. 246–255.
23. Dolotov A. S. Primenenie obratnogo osmosa v zamknutom vodooborote pri avtoklavnoy tekhnologii vskrytiya upornykh sulfidnykh Au-flotokontsentratov (Application of return osmosis in closed water circulation during the autoclave technology of opening of refractory sulfide Au-flotation concentrates). Materialy mezhdunarodnogo soveshchaniya “Plaksinskie chteniya – 2015” (Materials of international meeting “Plaksin readings – 2015”). Irkutsk, 2015. pp. 335–338.
24. Emelyanov Yu. E., Balikov S. V., Epiforov A. V., Bogorodskiy A. V., Kopylova N. V., Zolotarev F. D. Vliyanie prodolzhitelnosti avtoklavnogo okisleniya zolotosulfidnogo flotokontsentrata, soderzhashchego organicheskiy
uglerod, na izvlechenie zolota pri tsianirovanii (Influence of the length of pressure oxidation of gold-sulfide organic carbon containing flotation concentrate on gold extraction during cyanidation). V sbornike: Sovremennye metody tekhnologicheskoy mineralogii v protsessakh kompleksnoy i glubokoy pererabotki mineralnogo syrya (Plaksinskie chteniya – 2012) (In the collection: Modern methods of technological mineralogy in the processes of complex and deep processing of mineral raw materials (Plaksin readings – 2012)). Petrozavodsk, 2012. pp. 315–317.
25. Bogorodskiy A. V., Balikov S. V., Emelyanov Yu. E., Epiforov A. V., Shketova L. E., Nikolaev Yu. L. Sopostavitelnaya otsenka variantov pererabotki upornykh sulfidnykh flotokontsentratov (The assessment of options for processing refractory flotation concentrates). Tsvetnye Metally = Non-ferrous metals. 2012. No. 8. pp. 10–12.
26. Zaytsev P. V., Fomenko I. V., Chugaev L. V., Shneerson Ya. M. Avtoklavnoe okislenie syrya dvoynoy upornosti v prisutstvii izvestnyaka (Pressure oxidation of double refractory raw materials in the presence of limestone). Tsvetnye Metally = Non-ferrous metals. 2015. No. 8. pp. 41–49. DOI: http://dx.doi.org/10.17580/tsm.2015.08.05
27. Polezhaev S. Yu., Cheremisina O. V. Kompleksnaya tekhnologiya pererabotki zolotosoderzhashchikh kontsentratov: avtoklavnoe vyshchelachivanie s posleduyushchim obzhigom (Complex Processing Technology of Gold-Containing Concentrates: Autoclave Leaching with Subsequent Roasting). Izvestiya vuzov. Tsvetnaya metallurgiya = Universities' Proceedings. Nonferrous Metallurgy. 2015. No. 3. pp. 34–39.
28. Boldyrev A. V., Balikov S. V., Gudkov S. S., Bogorodskiy A. V., Emelyanov Yu. E. Avtoklavnoe okislenie upornykh zolotosoderzhashchikh kontsentratov s dobavleniem galogensoderzhashchikh rastvoriteley i sorbenta (Pressure oxidation of refractory gold-bearing concentrates with addition of halogene-containing dissolvents and sorbent). Materialy mezhdunarodnogo soveshchaniya “Plaksinskie chteniya – 2013” (Materials of international meeting “Plaksin readings – 2013”). Tomsk, 2013. p. 362.
29. Boldyrev A. V., Balikov S. V., Gudkov S. S., Bogorodskiy A. V., Emelyanov Yu. E. Optimizatsiya protsessa avtoklavno-sorbtsionnogo okisleniya upornykh zolotosoderzhashchikh kontsentratov (Optimization of the process of pressuresorption oxidation of rafractory gold-bearing concentrates). Materialy mezhdunarodnogo soveshchaniya “Plaksinskie chteniya – 2014” (Materials of international meeting “Plaksin readings – 2014”). Almaty, 2014. p. 482.
30. Boldyrev A. V., Balikov S. V., Gudkov S. S., Emelyanov Yu. E., Bogorodskiy A. V. Povyshenie effektivnosti avtoklavno-sorbtsionnoy tekhnologii pererabotki upornogo zolotosoderzhashchego syrya (Increasing of efficiency of autoclavesorption technology of processing of refractory gold-bearing raw materials). Zolotodobycha = Gold mining. 2014. No. 9 (190). pp. 8–10.
31. Boldyrev A., Balikov S., Gudkov S., Bogorodsky A., Yemelianov Y. Pressure oxidation of refractory gold-bearing concentrates using halide-based lixiviants and an adsorbent. 26^th International Mineral Processing Congress 2014. Santiago, Chile, 2014. pp. 83–86.
32. Boldyrev A. V., Balikov S. V., Gudkov S. S., Emelyanov Yu. E., Bogorodskiy A. V. Ispolzovanie galogensoderzhashchikh rastvoriteley i granulirovannykh ugley v protsesse avtoklavno-sorbtsionnogo vyshchelachivaniya dragotsennykh metallov iz upornykh sulfidnykh kontsentratov (Using halogene-bearing dissolvents and granulated coals in the process of autoclave-sorption leaching of precious metals from refractory sulfide concentrates). Materialy IV Vserossiyskoy nauchno-prakticheskoy konferentsii “Perspektivy razvitiya tekhnologii pererabotki uglevodorodnykh, rastitelnykh i mineralnykh resursov” (Materials of the IV All-Rus sian scientificpractical conference “Prospects of development of technology of proces sing of hydrocarbon, natural and mineral resources”). Irkutsk, 2014. pp. 9–10.
33. Boldyrev A. V., Balikov S. V., Gudkov S. S., Emelyanov Yu. E., Bogorodskiy A. V. Optimizatsiya protsessa avtoklavno-sorbtsionnogo okisleniya upornykh zolotosoderzhashchikh kontsentratov (Optimization of the process of autoclavesorption oxidation of refractory gold-bearing concentrates). Vestnik Irkutskogo gosudarstvennogo tekhnicheskogo universiteta = Bulletin of Irkutsk State Technical University. 2014. No. 12. pp. 191–195.
34. Boldyrev A. V., Balikov S. V., Gudkov S. S., Emelyanov Yu. E., Bogorodskiy A. V. Izvlechenie zolota iz upornykh sulfidnykh kontsentratov v protsesse avtoklavnogo okisleniya s ispolzovaniem sorbenta i galogensoderzhashchikh rastvoriteley (Optimization of process of pressure oxidationsorption (poxs) of refractory gold bearing concentrates). Gornyy informatsionno-analiticheskiy byulleten = Mining Informational and Analytical Bulletin. 2015. No. 9. pp. 34–40.
35. Balikov S. V., Bogorodskiy A. V., Emelyanov Yu. E. Avtoklavnoe okislenie upornykh zolotosoderzhashchikh kontsentratov s ispolzovaniem galogensoderzhashchikh rastvoriteley i sorbenta (Pressure oxidation of refractory gold-bearing concentrates using halogen-containing solvents and adsorbent). Tsvetnye Metally = Non-ferrous metals. 2015. No. 11. pp. 29–32. DOI: http://dx.doi.org/10.17580/tsm.2015.11.04
36. Boldyrev A. V., Balikov S. V., Gudkov S. S., Emelyanov Yu. E., Bogorodskiy A. V. Avtoklavno-sorbtsionnoe izvlechenie zolota iz upornykh sulfidnykh kontsentratov (Pressure-sorption extraction of gold from refractory sulfide concentrates). Materialy mezhdunarodnogo soveshchaniya “Plaksinskie chteniya – 2015” (Materials of international meeting “Plaksin readings – 2015”). Irkutsk, 2015. pp. 330–331.
37. Zolotarev F. D., Aleksandrova T. N., Bogorodskiy A. V., Zhadovskiy I. T. Ispolzovanie galogensoderzhashchikh rastvoriteley blagorodnykh metallov v tekhnologii avtoklavnogo okisleniya (Use of halogen containing noble metal solvents in pressure oxidation technology). Tsvetnye Metally = Non-ferrous metals. 2015. No. 10. pp. 60–63. DOI: http://dx.doi.org/10.17580/tsm.2015.10.10
38. Lapin A. Yu., Bitkov G. A., Shneerson Ya. M. Avtoklavno-gidrometallurgicheskaya pererabotka upornykh zolotosoderzhashchikh sulfidnykh materialov pri ponizhennykh temperaturakh (Autoclave-hydrometallurgical processing of refractory gold-bearing sulfide materials during the decreased temperatures). Tsvetnye Metally = Non-ferrous metals. 2011. No. 12. pp. 39–44.
39. Bitkov G. A., Lapin A. Yu., Shneerson Ya. M. Pererabotka upornykh zolotosulfidnykh kontsentratov avtoklavnym okisleniem pri umerennykh temperaturakh (Autoclave oxidation processing of refractory gold-containing sulphide concentrates at moderate temperatures). Tsvetnye Metally = Nonferrous metals. 2014. No. 1. pp. 44–52.
40. Epiforov A. V. Nizkotemperaturnoe avtoklavnoe okislenie upornykh sulfidnykh zolotomednykh kontsentratov : avtoreferat dissertatsii ... kandidata tekhnicheskikh nauk (Low-temperature pressure oxidation of refractory sulfide gold-copper concentrates : thesis of Inauguration of Dissertation ... of Candidate of Engineering Sciences). Irkutsk, 2014. 17 p.
41. Zakharov B. A., Shneerson Ya. M., Chugaev L. V., Zhunusov M. T., Drozdov S. V., Pleshkov M. A., Markelov A. V. Razrabotka tekhnologii avtoklavnoy pererabotki kontsentratov i promproduktov Olimpiadinskogo gorno-oboga titalnogo kombinata zakrytogo aktsionernogo obshchestva “Polyus” (Development of technology of autoclave processing of concentrates and middlings of Olimpiada ore-dressing and processing enterprise (JSC “Polus”)). Zoloto i tekhnologii = Gold and Technologies. 2013. No. 3 (21). pp. 24–28.
42. Shneerson J. M., Zhunusov M. T., Chugaev L. V., Markelov A., Drozdov S. Autoclave technology of refractory gold-bearing pyrrhotite concentrates and residues of bioleaching. Proceedings of ALTA 2013 Gold conference. Perth, Australia, 2013. pp. 98–109.
43. Shneerson Ya. M., Chugaev L. V., Zhunusov M. T., Markelov A. V., Drozdov S. V. Avtoklavnoe dookislenie tverdogo ostatka biookisleniya flotokontsentrata (Autoclave oxidation of the solid residue of the float concentrate biooxidation). Tsvetnye Metally = Non-ferrous metals. 2012. No. 6. pp. 34–37.
44. Shneerson Ya. M., Chugaev L. V., Zhunusov M. T., Markelov A. V., Drozdov S. V. Kompleksnaya tekhnologiya pererabotki zolotosoderzhashchikh kontsentratov: biovyshchelachivanie i avtoklavnoe dookislenie (Complex technology of processing of gold-bearing concentrates: bioleaching and pressure re-oxidation). Tsvetnye metally – 2013 : sbornik nauchnykh statey (Non-ferrous metals – 2013 : collection of scientific proceedings). Krasnoyarsk : Verso, 2013. pp. 576–583.
45. Zaharov B. A., Shneerson J. M., Chugaev L. V., Zhunusov M. T., Drozdov S. V., Markelov A. V. Development of autoclave processing POX technology for Olympiada sulfide concentrates and biooxidated products feedstocks. Proceedings of the 7th International Symposium of Hydrometallurgy 2014. Victoria, BC, 2014. pp. 751–761.
46. Bolobov V. I., Shneerson Ya. M., Lapin A. Yu., Bitkov G. A. Povedenie khromonikelevykh splavov v protsesse avtoklavnogo nizkotemperaturnogo okisleniya upornogo sulfidnogo zolotosoderzhashchego syrya (Behavior of chromium-nickel alloys, during the process of low-temperature autoclave oxidation of refractory sulfide gold-containing raw materials). Tsvetnye Metally = Non-ferrous metals. 2013. No. 2. pp. 76–81.
47. Dzgoev Ch. T., Evtushevich I. I., Shtoyk S. G., Epiforov A. V., Gudkov S. S., Emelyanov Yu. E., Balikov S. V. Avtoklavno-pirometallurgicheskaya tekhnologiya pererabotki sulfidnykh zolotosoderzhashchikh i svintsovo-tsinkovykh flotokontsentratov (Autoclave-pyrometallurgical technology of processing of sulfide gold-bearing and lead-zinc flotation concentrates). Materialy mezhdunarodnogo soveshchaniya “Plaksinskie chteniya – 2015” (Materials of international meeting “Plaksin readings – 2015”). Irkutsk, 2015. pp. 338–340.
48. Filyanin G. A., Vorobev-Desyatovskiy N. V. Amurskiy gidrometallurgicheskiy kombinat — klyuchevoy element pererabatyvayushchego uzla otkrytogo aktsionernogo obshchestva “Polimetall” na Dalnem Vostoke (Amursk hydrometallurgical plant is a key element of processing unit of Far Eastern “Polymetal” JSC). Tsvetnye Metally = Non-ferrous metals. 2014. No. 6. pp. 29–36.
49. Amurskiy Gorno-Metallurgicheskiy Kombinat (Amursk POX Hub). Polymetall International PLC. Available at : http://www.polymetal.ru/operations-landing/amursk-pox/overview.aspx?sc_lang=ru-RU (in Russian)
50. Petropavlovsk signs agreement with GMD Gold to finance the completion of the Pressure Oxidation Project. “Petropavlovsk” PLC. Available at : http://www.petropavlovsk.net/images/stories/Pressreleases/2016/Joint_Venture.pdf
51. Yuzhuralzoloto gruppa kompaniy: Proizvodstvennye rezultaty po itogam 1K 2013 goda (The Gold Mining Company: Production results by the 1 quarter of 2013). The Gold Mining Company. Available at : http://ugold.ru/ru/press/news/detail.php?ID=88 (in Russian)
52. Shepelevich A. V., Obraztsova O. V. Obshchestvo s ogranichennoy otvetstvennostyu Torgovyy dom “Pressmash” v oblasti obogashcheniya rud: avtoklavnoe vyshchelachivanie, pachuki, sgustiteli (LLC Trading House “Pressmash” in the area of ore concentration: autoclave leaching, pachuca tanks, thickeners). Zoloto i tekhnologii = Gold and Technologies. 2012. No. 4 (18). pp. 22–25.