Designs, technologies and temperature conditions of frozen structures in placer mines in the North

Many gold mines in Russia are located in the Far East, including the permafrost zone. Efficient mining of deep placers in such conditions is only possible with the underground method. It is proposed to ensure roof support in mined-out areas in placer mines using frozen rock pillars of an original design capable to provide an increased load-bearing capacity. Such pillars are constructed using an improved technology, with metal pipes placed layer by layer in the body of a pillar at certain intervals. Efficiency of the proposed method for pillar freezing is evaluated using the developed mathematical model. The model uses the two-dimensional nonlinear equation of thermal conduction (Stefan problem), which enables prediction of temperature condition in the frozen pillar and enclosing permafrost formation in placer mines. The new computer program allows selecting geometry of a frozen rock pillar, construction dates, physicotechnical properties of rocks, as well as the number and arrangement of metal pipes to inject cool air for more intense freezing of the pillar. Computer modeling is undertaken to compare the rate of construction of a frozen rock pillar using the conventional and proposed methods. The modeling results confirm that freezing of a pillar of a proposed design takes much shorter time as against the conventional approach due to the forced circulation of cool air in pipes. Dynamics of cooling and subsequent freezing of a frozen rock pillar constructed in placer mines in the conditions of higher rate of ventilation is determined. The features of heat exchange between the frozen rock pillar and surrounding permafrost formation in placer mines are revealed. The feasibility of appreciable acceleration of freezing in the proposed-design frozen rock pillar and the resultant development of strength is proved. Such design frozen rock pillars possess high strength, ensure reliable support of mined-out areas and improve operational safety in placer mines in the permafrost zone.

Keywords: mathematical modeling, permafrost zone, placer mine, gold mining, underground openings, frozen rock pillar.
For citation:

Kaimonov M. V., Kiselev V. V. Designs, technologies and temperature conditions of frozen structures in placer mines in the North. MIAB. Mining Inf. Anal. Bull. 2020;(8):118129. [In Russ]. DOI: 10.25018/0236-1493-2020-8-0-118-129.

Acknowledgements:
Issue number: 8
Year: 2020
Page number: 118-129
ISBN: 0236-1493
UDK: 622:624.1
DOI: 10.25018/0236-1493-2020-8-0-118-129
Article receipt date: 17.01.2020
Date of review receipt: 27.03.2020
Date of the editorial board′s decision on the article′s publishing: 20.07.2020
About authors:

M.V. Kaimonov1, Cand. Sci. (Eng.), Senior Researcher,
V.V. Kiselev1, Cand. Sci. (Eng.), Senior Researcher,
1 Chersky Mining Institute of the North, Siberian Branch, Russian Academy of Sciences, 677018, Yakutsk, Republic of Sakha (Yakutia), Russia.

 

For contacts:

M.V. Kaimonov, e-mail: gtf@igds.ysn.ru.

Bibliography:

1. Podzemnaya razrabotka rossypnykh mestorozhdeniy: Bibliograficheskiy ukazatel' otechestvennoy lieratury. (1965—2001 gg.) [Underground mining of placers. Index to Russian literature (1965—2001)], Yakutsk, Tipografiya IM, 2002, 152 p.

2. Sal'manov R. N., Machnev F. F. Practicality of artificial frozen pillars in underground mining of permafrost placers. Kolyma. 1977, no 11, pp. 7—10. [In Russ].

3. Sal'manov R. N., Krasnykh S. N. Placer mining with frozen backfill. Kolyma. 1987, no 3, pp. 19—20. [In Russ].

4. Neobutov G. P., Grinev V. G. Razrabotka rudnykh mestorozhdeniy s ispol'zovaniem zamorazhivaemoy zakladki v usloviyakh mnogoletney merzloty Ore mining with frozen backfill in permafrost], Yakutsk, Izd-vo YANTS SO RAN, 1997, 104 p.

5. Petrov A. N., Alekseev A. M., Kolesnikov S. G., Petrov D. N. Engineering solutions on mining on subpermafrost layers in the Badran deposit. Gornyi Zhurnal. 2016, no 9, pp. 46—50. [In Russ].

6. Neobutov G. P., Petrov D. N., Nikulin E. V. New trends in mining technologies for lode deposits in the permafrost zone. MIAB. Mining Inf. Anal. Bull. 2009, no 4, pp. 14—22. [In Russ].

7. Kaymonov M. V., Khokholov Yu.A. Selecting composition for frozen fill masses. Fizikotekhnicheskiye problemy razrabotki poleznykh iskopayemykh. 2019, no 5, pp. 179—188. [In Russ].

8. Kiselev V. V., Khokholov Yu.A. Promising methods of secondary underground mining of deep residual placer blocks in the permafrost zone. MIAB. Mining Inf. Anal. Bull. 2015. Special edition 30, pp. 173—184. [In Russ].

9. Kiselev V. V., Khokholov Yu.A., Kaymonov M. V. Top-priority trends in underground gold mining and roof support in mined-out areas of placer mines in the permafrost zone. MIAB. Mining Inf. Anal. Bull. 2018, no 5, pp. 49—58. [In Russ].

10. Skudzzyk F. I., Barker I. C., Walsh D. Е., MacDonald R. Applicability оf Siberian placer mining technology tо Alaska; Finаl Report for the Alaska Scienceand Technology Foundation MIRL, Report № 89 University оf Alaska Fairbanks, 1991. 77 p.

11. Sherstov V.A., Sherstova L. I., Malikov E. F., Skryabin R. M. Zolotodobyvayushchaya promyshlennost' Alyaski [Gold mining in Alaska], Yakutsk, Izd-vo YANTS SO RAN, 1992, 44 p.

12. Tikhonov A. N., Samarskiy A. A. Uravneniya matematicheskoy fiziki [Mathematical physics equations], Moscow, Nauka, 2004, 798 p.

13. Belyaev N. M., Ryadno A. A. Metody teorii teploprovodnosti. Ch. 2 [Methods of the theory of heat conduction. Part 2], Moscow, Vysshaya shkola, 1982, 304 p.

14. Wei Cao, Yu Sheng, Jichun Wu, Jing Li, Yaling Chou, Jinping Li Simulation analysis of the impacts of underground mining on permafrost in an opencast coal mine in the northern Qinghai–Tibet Plateau. Environmental Earth Sciences. 2017. Vol. 76. No 20. Pp. 711.

15. Panteleev I.A., Kostina A. A., Plekhov O. A., Levin L.Y. Numerical simulation of artificial ground freezing in a fluid-saturated rock mass with account for filtration and mechanical processes. Sciencesin Cold and Arid Regions. 2017. Vol. 9. No 4. Pp. 1—15.

16. Zheng T., Miao X.-Y., Naumov D., Haibing Shao, Kolditz O., Nagel T. A Thermo-hydromechanical finite element model of freezing in porous media—thermo-mechanically consistent formulation and application to ground source heat pumps. VII International Conference on Computational Methods for Coupled Problems in Science and Engineering, 2017.

17. Seon Hong Na, Wai Ching Sun Computational thermo-hydro-mechanics for multiphase freezing and thawing porous media in the finite deformation range. Computer Methods in Applied Mechanics and Engineering. 2017. Vol. 318. No 667. DOI: 10.1016/j.cma.2017.01.028

18. Mikkola M., Hartikainen J. Mathematical model of soil freezing and its numerical implementation. International Journal for Numerical Methods in Engineering. 2001. Vol. 52(5–6). Pp. 543—557.

19. Bogomolov A. I., Mikhaylov K. A. Gidravlika [Hydraulics], Moscow, Stroyizdat 1972, 648 p.

20. Samarskiy A. A., Vabishchevich P. N. Vychislitel'naya teploperedacha [Computational heat transfer], Moscow, Едиториал УРСС, 2014, 784 p

21. Samarskiy A. A. Teoriya raznostnykh skhem [Theory of difference schemes], Moscow, Nauka, 1983, 616 p.

22. Musakaev N. G., Romanyuk S. N., Borodin S. L. Numerical research of phase transfer advance patterns in permafrost rocks. Izvestiya vysshikh uchebnykh zavedeniy. Neft' i gaz. 2011, no 6, pp. 122—128. [In Russ].

23. Khasanov M. K., Stolpovskiy M. V. Numerical solution of a Stefan’s problem with a number of phase boundaries with the trapping of phase transfers in the mesh nodes. Fundamental'nye issledovaniya. 2015, no 11 (ч. 4), pp. 748—752. [In Russ].

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