Technical Institute (Division), Ammosov North-Eastern Federal University, Neryungri, Russia:

V. F. Rochev, Associate Professor, Candidate of Engineering Sciences, viktor-rochev74@mail.ru

Placer mining of gold in Southern Yakutia uses mainly opencast method, the underground approach is employed less often. However, the former method of mineral mining has high aggravating effect on the environment, while the latter approach consumes much labor and money. It is suggested to use an alternative method of surface borehole hydraulic mining. (SBHM). Gold placers have favorable ground conditions for SBHM. The productive stratum is represented by readily breakable incoherent or weakly coherent rocks, and thawed gold placer contain much water, which allows gold sand extraction with highduty air lift equipment, and the productive stratum in frozen placers has stable roof, and the overlying rocks possess drillability category III–IV, which offers comparatively low cost of drilling in such rocks. Recently in the Republic of Sakha (Yakutia) new god placers buried at a depth from 40 to 250 m are being increasingly discovered and explored. Metal content often reaches a few tens of grams per 1 m² of stratum, which makes the placers promising for mining with SBHM. Gold reserves in such placers reach tens of tones. In view of depletion of mineral reserves suitable for open pit mining, as well as considering technical difficulties and high cost of underground mining of buried placers, there are prospects for gold extraction with SBHM. The estimate of the applicability of the discussed method under conditions of Southern Yakutia is critical task. The geological analysis points at many gold placer suitable for surface borehole hydraulic mining in Southern Yakutia. At the same time, the majority of the placers are insuffi ciently explored since they are uneconomical for traditional open pit or underground mining. Thick frozen rock strata in permafrost zone are also suitable for surface borehole hydraulic mining. This method of gold extraction causes minor environmental damage, ensures safe operating conditions, allows automation of washing and discharge of gold-bearing rocks to ground surface and enables high technical and economic indexes. Yet, SBHM method needs comprehensive scientific studies and testings to improve its reliability and expand application range.

1. Arens V. Zh., Gridin O. M., Kreynin E. V., Nebera V. P., Fazlullin M. I., Khrulev A. S., Khcheyan G. Kh. Physical and chemical geotechnology : tutorial for universities. Moscow : Gornaya kniga, 2010. 575 p.
2. Arens V. Zh., Babichev N. I., Bashkatov A. D. et al. Hydraulic borehole mining of minerals : tutorial. Moscow : Gornaya kniga, 2011. 295 p.
3. Arens V. Zh., Khcheyan G. Kh., Khrulev A. S. Method of experimental-industrial investigations of hydraulic borehole mining. Marksheyderskiy vestnik. 2010. No. 3. pp. 13–17.
4. Bagazeev V. K., Valiev N. G., Simisinov D. I. Physico-mechanical substantiation of rock mass jetting in hydraulic borehole mining of placers. Gornyy Zhurnal. 2015. No. 12. pp. 25–27. doi: dx.doi.org/10.17580/gzh.2015.12.05
5. Valiev N. G., Bagazeev V. K. Calculating the parameters of sewage extraction wells at hydraulic wells mining. Izvestiya vuzov. Gornyy Zhurnal. 2012. No. 1. pp. 13–16.
6. Drobadenko V. P., Malukhin N. G., Vilmis A. L. Problems and prospects of hydraulic borehole mining of minerals. Zolotodobycha. 2011. No. 155. pp. 17–19.
7. Ermakov S. A., Burakov A. M., Batugina N. Continuous flow process technology for gold extraction and beneficiation at the buried placer in the Bolshoi Kuranakh River valley (Yakutia). Gornyy Zhurnal. 2016. No. 1. pp. 40–45. doi: dx.doi.org/10.17580/gzh.2016.01.09
8. Zamyatin O. V., Mankov V. M. Fine gold in placers : problems of assessment and extraction. Gornyy Zhurnal. 2011. No. 4. pp. 22–26.
9. Streltsov V. I., Volkov Yu. I., Balashov A. G., Streltsova T. P. Complex mastering of soils by hydraulic borehole mining. Gornyy Zhurnal. 2010. No. 7. pp. 33–36.
10. Ashok Amin. Large Hydraulic Direct Drives in Mining Operations. Engineering and Mining Journal. October 2015. pp. 52–56.
11. Leiserowitsch S., Ibragimova E., Ibragimov I. New High Performance Georadar with up to 1 km Resolution. 13-th International Conference on Grounol Penetration Radar, 21–25 June 2010. Lecce, Italy, 2010. p. 6.
12. Hellström G. Large-Scale Applications of Ground-Source Heat Pumps in Sweden. IEA HP Annex 29 Workshop. Zurich, 2008. pp. 22–23.
13. Kozioł W., Machniak Ł., Ciepliński A. Technologie wydobycia kruszyw żwirowo-piaskowych spod wody. Przegląd Górniczy. 2011. No. 7-8. pp. 207–214.
14. Yu-Ying Zhang, Yong-Wang Liu, Yi-ji Xu, Jian-Hua Ren. Drilling characteristics of combinations of different high pressure jet nozzles. Journal of Hydrodynamics. Series B. 2011. Vol. 23, Iss. 3. pp. 384–390.