Improved gold diagnostic leaching procedure for carbonaceous preg-robbing ores

The article presents an improved procedure for the diagnostic leaching of gold in carbonaceous preg-robbing mineral ores. When researching highly preg-robbing ores, classic diagnostic gold leaching approaches often lead to distorted results: the proportion of cyanidable gold is underestimated, while recoverable gold is er roneously attributed to refractory forms. This discrepancy arises from the high natural sorption activity of organic carbon, which interferes with artificial sorbents at all leaching stages to competitively adsorb gold from the liquid phase of cyanide pulp. An advanced diagnostic two-stage leaching procedure for highly preg-robbing materials has been developed: first, cyanidation is carried out under standard conditions with an increased sorbent load, then high-temperature sorption processing at a temperature of 80–95°C for 2 hours is carried out with fresh sorbent. Tests carried out on various carbonaceous mineral products demonstrated improved gold recovery efficiency during cyanidation. The 4.2–12.5 % increase in obtained cyanidable gold as compared to the conventional method enables more precise differentiation of gold forms and optimization of processing strategies for preg-robbing ores. This pro cedure is particularly valuable for ores having a high organic carbon content and strong preg-robbing capacity due to providing more reliable phase characterization of gold and supporting accurate selection of processing technolo gies. The protocol is recommended for implementation in both laboratory and industrial practice.

1. Edahbi M., Ounoughi M., Bouzahzah H., Boujlel K. CIL gold loss characterization within oxidized leach tails: creating a synergistic approach between mineralogical characterization, diagnostic leach tests, and preg-robbing tests. Minerals. 2019;9(9):557. https://doi.org/10.3390/min9090557.

2. Saders J.A., Gravel J., Janke L., Hall L. In-depth study on carbon speciation focussed on graphite. In: Symposium on Strategic and Critical Materials Proceedings. 13–14 November 2015, Victoria. Victoria: British Columbia Ministry of Energy and Mines; 2015, p. 187-191.

3. Bas A.D., Altinkaya P., Yazici E.Y., Deveci H. Preg-robbing potential of sulphide-bearing gold ores. In: Proceedings of 13th International Mineral Processing Symposium-IMPS. 10–12 October 2012, Bodrum. Bodrum; 2012, р. 613-618.

4. Borges G.F. Efeito preg-robbing em minerais auríferos por compostos carbonáceos: estado da arte. Ouro Preto: Escola de Minas, Universidade Federal de Ouro Preto; 2021, 48 р.

5. Mabwe N.R. Potential pre-treatment and processing routes for recovery of gold from complex (refractory) gold ores. A review. In: Proceedings of the 2nd African International Conference on Industrial Engineering and Operations Management. 7–10 December 2020, Harare. Harare; 2020, p. 1708-1715.

6. Cetin M.C., Altun N.E., Atalay M.Ü., Büyüktanır K. Bottle roll testing for cyanidation of gold ores: problems related to standardized procedures on difficult-to-process ores. In: Proceedings of the 3rd World Congress on Mechanical, Chemical, and Material Engineering. 8–10 June 2017, Rome. Rome; 2017, p. 148. https://doi.org/10.11159/mmme17.148.

7. Dunne R., LeVier M., Acar S., Kappes R. Keynote address: Newmont’s contribution to gold technology. In: World Gold Conference. 2009, Johannesburg. Johannesburg: Southern African Institute of Mining and Metallurgy; 2009, p. 221-230.

8. Byvaltsev A.V., Voiloshnikov G.I., Khmelnitskaya O.D., Bogorodskiy E.V. Problems of processing carbonaceous sorption-active gold ores. The theory and process engineering of metallurgical production. 2024;51(4):18-23. (In Russ.). EDN: PTZFQB.

9. Asamoah R.K., Amankwah R.K., Addai-Mensah J. Cyanidation of refractory gold ores: A Review. In: 3rd UMaT Biennial International Mining and Mineral Conference. Juli 2014, Tarkwa. Tarkwa; 2014, p. 204-212. https://doi.org/10.13140/2.1.4772.6407.

10. Mustapha A., Asamoah R.K., Ofori-Sarpong G., Amankwah R.K. Preg-robbing characteristics of gold ores in Ghana. In: 3rd UMaT Biennial International Mining and Mineral Conference. Juli 2014, Tarkwa. Tarkwa; 2014, p. 192-196.

11. Ahtiainen R., Lundström M., Liipo J. Preg-robbing verification and prevention in gold chloride-bromide leaching. Minerals Engineering. 2018;128:153-159. https://doi.org/10.1016/j.mineng.2018.08.037.

12. Byvaltsev A.V., Voiloshnikov G.I., Khmelnitskaya O.D. A procedure for preparing carbonaceous cyanidation tailings for gold fire assay. iPolytech Journal. 2025;29(1):123-132. (In Russ.). https://doi.org/10.21285/1814-3520-2025-1-123-132.

13. Helm M.M., Vaughan J.P., Staunton W.P. Evaluation of preg-robbing in Goldstrike carbonaceous ore using Raman spectroscopy. In: Proceedings of the 50th Conference of Metallurgists. 2–5 Оctober 2011, Мontreal. Montreal; 2011, р. 595-606.

14. Lodeishchikov V.V. Technology of gold and silver extraction from refractory ores. Irkutsk: Irgiredmet; 1999,786 p. (In Russ.).

15. Zelenov V.I. Methodology for studying gold- and silver-bearing ores. Moscow: Nedra; 1989, 302 р. (In Russ.).

16. Stephen R.S., Anuar W.N.S., Ismail S., Jabit N.A. Characterisation and diagnostic leaching of gold-bearing mineral ore, east coast peninsular Malaysia. Malaysian Journal of Microscopy. 2021;17(2):139-153.

17. Guner M.K., Bulut G., Hassanzadeh A., Lode S., Aasly K. Automated mineralogy and diagnostic leaching studies on bulk sulfide flotation concentrate of a refractory gold ore. Minerals. 2023;13(10):1243. https://doi.org/10.3390/min13101243.

18. Henley K.J., Clarke N.C., Sauter P. Evaluation of a diagnostic leaching technique for gold in native gold and gold ± silver tellurides. Minerals Engineering. 2001;14(1):1-12. https://doi.org/10.1016/S0892-6875(00)00156-4.

19. Celep O., Alp I., Deveci H. Application of diagnostic leaching technique for refractory gold ores. D.P.Ü. Fen Bilimleri Enstitüsü Dergisi. 2008;16:81-90.

20. Bekpulatov Zh.M., Khudaiberdiev F.T. Studying material composition and development of processing technology for a gold-bearing ore sample from one of the Uzbekistan Republic deposits. Innovatsionnaya nauka. 2017;3(4):20 23. (In Russ.). EDN: YLZMAH.

21. Shumilova L.V. Refractory auriferous ore technological testing (by the example of Kokpatas deposit). Chita State University Journal. 2009;3:42-47. (In Russ.). EDN: KYAPVT