Saint Petersburg Mining University, Saint Petersburg, Russia

Bolobov V. I., Professor, Senior Researcher, Doctor of Engineering Sciences
Chupin S. A., Associate Professor, Candidate of Engineering Sciences, chupin_sa@pers.spmi.ru

Vinacomin—Institute of Energy & Mining Mechanical Engineering (IEMM), Hanoi, Vietnam

Le-Thanh B., Senior Researcher

The necessary condition for the operation of crushers in the production of crushed granite is feeding of the crushers with granite fragments of a certain size. At the same time, granite fragmentation after blasting does not always meet the required size for the crushers and needs additional destruction by blasting or disintegration directly on site. Hydraulic breakers are most often used in disintegration of oversizes. For example, in quarries in Vietnam, JCB HM380 hydraulic breakers with a fracture energy of up to 2.5 kJ are widely used. The working tools of the hydraulic breakers are steel picks of various diameters and shapes. The operation of this tool is accompanied by its intensive wear due to the impact-abrasive action of rocks; the pointed part of the tool gets gradually blunted, which affects the rate of penetration of the pick in rock. In this regard, it is relevant to determine the influence exerted by the degree of wear of the pick on the performance of the hydraulic breaker, and to find out whether replacement or re-sharpening of the pick is expedient. In this paper, based on the previously determined crack propagation velocity in granite and the impact time, the length of the fracture is calculated. The dimensions of a crack in a granite block are calculated depending on the degree of blunting of the pick at a certain number of blows per cycle. At the same time, the limiting value of a crack that causes chipping of a piece from rock mass was considered as the fracture length to free surface at different degrees of pick blunting. Based on these calculations, the average productivity and energy input of disintegration process were determined. It is shown that for a tool with a completely worn tip, the decrease in the productivity and the increase in the energy input of fracture reach two times compared with a sharpened pick. In this regard, from the point of view of increasing the hydraulic breaker capacity, it is advisable to replace or re-sharpen the pick after complete wear of its tip.

1. Nguyen B. N, Boruff B., Tontsb M. Looking through a crystal ball: Understanding the future of Vietnam’s minerals and mining industry. The Extractive Industries and Society. 2021. Vol. 8, Iss. 3. ID. 100907.
2. Gabov V. V., Zadkov D. A., Nguyen Khac Linh. Features of elementary burst formation during cutting coals and isotropic materials with reference cutting tool of mining machines. Journal of Mining Institute. 2019. Vol. 236. pp. 153–161.
3. Fomin K. V. Method for estimating the spectrum density of the resistance moment on the working body of a peat milling unit. Journal of Mining Institute. 2020. Vol. 241, No. 1. pp. 58–67.
4. Yungmeister D. A., Lavrenko S. A., Yacheikin A. I., Urazbakhtin R. Y. Improving the shield machine cutter head for tunneling under the conditions of the Metrostroy Saint Petersburg mines. ARPN Journal of Engineering and Applied Sciences. 2020. Vol. 15, No. 11. pp. 1282–1288.
5. Lebedeva Y. A., Kotiukov P. V., Lange I. Y. Study of the geo-ecological state of groundwater of metropolitan areas in the conditions of intensive contamination thereof. Journal of Ecological Engineering. 2020. Vol. 21, No. 2. pp 157–165.
6. Mikhaylov A. V., Rodionov E. A., Zvonarev I. E. Analysis of conditions for vertical cutting of peat. GIAB. 2019, No. 1. pp. 48–54.
7. Khoreshok A., Mametyev L., Nesterov V., Tsekhin A., Borisov A. Justification of the disk tool application for working bodies of mining machines. MATEC Web of Conferences. 2019. Vol. 297. ID. 03007.
8. Gabov V. V., Zadkov D. A., Babyr N. V., Fangwei X, Nonimpact rock pressure regulation with energy recovery into the hydraulic system of the longwall powered support. Eurasian Mining. 2021. No. 2. pp. 55–59.
9. Malyshkov G. B., Sinkov L. S., Nikolaichuk L. A. Analysis of economic evaluation methods of environmental damage at calculation of production efficiency in mining industry. International Journal of Applied Engineering Research. 2017. Vol. 12, No. 10. pp. 2551–2554.

10. Strizhenok A. V., Ivanov A. V. Monitoring of air pollution in the area affected by the storage of primary oil refining waste. Journal of Ecological Engineering. 2021. Vol. 22, No. 1. pp. 60–67.
11. Prokopenko S. A., Ludzish V. S., Li A. A. Recycling possibilities for reducing waste from cutters on combined cutter–loaders and road builders. Waste Management and Research. 2017. Vol. 35, No. 12. pp. 1278–1284.
12. Prokopenko S. A., Vorobiev A. V. Recovery of worn-out picks in rock breaking. Eurasian Mining. 2018. No. 1. рр. 27–30.
13. Boikov A., Payor V., Savelev R. Synthetic data generation for steel defect detection and classification using deep learning. Symmetry. 2021. Vol. 13, No. 7. 1175.
14. Zhukovskiy Y. L., Batueva D. E., Buldysko A. D., Gil B., Starshaia V. V. Fossil energy in the framework of sustainable development: Analysis of prospects and development of forecast scenarios. Energies. 2021. Vol. 14, No. 17. ID. 5268.
15. Yungmeister D. A. Research of modernized perforator-hammer for drifting special roadway in underground mines Metrostroy. Journal of Mining Institute. 2016. Vol. 218. pp. 281–288.
16. Klishin V. I., Gerike B. L., Nikitenko S. M., Krestovozdvizhensky P. D. Types and causes of failure of tangential-rotary cutter bits. Gornyi Zhurnal. 2016. No. 7. pp. 92–95.
17. Alexandrov V. I., Kibirev V. I., Serzhan S. L. The effectiveness of polyurethane coatings on internal surfaces of slurry lines in tailings slurry hydrotransport systems. Obogashchenie Rud. 2020. No. 4. pp. 35–41.
18. Sementsov V. V., Prokopenko S. A., Ludzish V. S., Abramov V. V. Design and industrial testing of innovative nonexpendable picks for cutter-loaders. Eurasian Mining. 2019. No. 2. pp 59–63.
19. Fedorova L. V., Ivanova Yu. S., Voronina M. V. Improvement of threaded joint reliability by means of electromechanical processing. Journal of Mining Institute. 2017. Vol. 226. pp. 456–461.
20. Fedorov S. K., Fedorova L. V., Ivanova Y. S., Voronina M. V., Sadovnikov A. V. et al. Increasing the wear resistance of adapters and drill pipes by electromechanical processing. Journal of Mining Institute. 2018. Vol. 233. pp. 539–546.
21. Zhabin A. B., Polyakov A. V., Averin E. A. et al. Estimation of abrasiveness impact on the parameters of rock-cutting equipment. Journal of Mining Institute. 2019. Vol. 240. pp. 621–627.
22. Korotkov V. A., Lipatov A. G., Vesnin A. M.Innovative technologies for repairand-renewal maintenance and life extension for parts and units of mining and processing equipment. Gornyi Zhurnal. 2015. No. 8. pp. 83–87.
23. Korneev V. A., Korneev P. A., Krestovozdvizhensky P. D., Pugachev E. V. Improvement of drilling cutter design. Gornyi Zhurnal. 2020. No. 12. pp. 67–70.
24. Sinev S. V. Rock drillability and the most efficient drilling tool selection. Gornyi Zhurnal. 2018. No 12. pp. 59–64.
25. Kallel M., Zouch F., Antar Z., Bahri A., Elleuch K. Hammer premature wear in mineral crushing process. Tribology International. 2017. Vol. 115. pp 493–505.
26. Marseden P., Pollok M. Buyers’ Guide, Breakers. Demolition and recycling international. 2004. pp. 15–30.
27. Ushakov L. S., Kamanin Yu. N. Stress–strain analysis of rock mass in fracture by shearing percussion tool. Gornoe Oborudovanie i Elektromehanika. 2008. No. 4. pp. 40–42.
28. Lagunova Yu. A. Working out the mathematical model of the process destroying mining rocks “In layer”. Gornoe Oborudovanie i Elektromehanika. 2008. No. 11. pp. 38–43.
29. Zedgenizov V. G., Melnikov A. V. Modeling work process of impactor in fracture of rocks and strong building materials. Gornoe Oborudovanie i Elektromehanika. 2008. No. 2. pp. 39–43.
30. Zedgenizov V. G., Al-Sakkaf Khaled Saed Taha. Some regularities of destruction of rocks at shock interaction of the wedge-shaped tool with not dimension. Mining Equipment and Electromechanics. 2012. No. 8. pp. 28–31.
31. Chupov I. V. Interrelation of specific energy of rock fracture and unit blow energy. Izvestia Vuzov. Gornyi Zhurnal. 2006. No. 5. pp. 66–69.
32. Grantmyre I., Hawkes I. High-energy impact rock breaking. CIM Bulletin. 1975. pp. 63–70.
33. Wayment W. R., Grantmyre I. P. Development of a high blow energy hydraulic impactor. Proceedings of the Rapid Excavation and Tunneling Conference. 1976. pp. 611–626.
34. Mahyera A., McDonald R. C., Koenning T. H. Predicting performance of joy Heftiimpactors for secondary breaking. Proceedings of the 14^th Canadian Rock Mechanics Symposium, Vancouver, CIM Special. 1982. No. 30. pp. 59–63.
35. Afrouz A., Hassani F. P. An investigation into rock breaking by direct impact. Mining Science and Technology. 1987. Vol. 4, No. 2. pp. 167–176.
36. Bilgin N., Yazici S., Eskikaya S. A. Model to predict the performance of roadheaders and impact hammers in tunnel drivages. Proceedings, Eurock 96, Torino, Balkema. 1996. pp. 715–720.
37. Bilgin N., Kuzu C., Eskikaya S. Cutting performance of jack hammers and roadheaders in Istanbul metro drivages. Proceedings, World Tunnel Congress, Wienna, Balkema. 1997. pp. 455–460.
38. Bilgin N., Dincer T., Copur H. The performance prediction of impact hammers from Schmidt hammer rebound values in Istanbul metro tunnel drivages. Tunneling and Underground Space Technology. 2002. Vol. 17, No 3. pp. 237–247.
39. Khoreshok A., Mametiev L., Tsekhin A., Borisov A. Relationship between the power of the two-bit cutting body rotation drive of the roadheader and hardness of broken rock. 3^rd International Innovative Mining Symposium : E3S Web of Conferences. 2018. Vol. 41(54). DOI: 10.1051/e3sconf/20184103017
40. Aksoy C.O. Performance prediction of impact hammers by block punch index for weak rock masses. International Journal of Rock Mechanics and Mining Sciences. 2009. Vol. 46, No 8. pp 1383–1388.
41. Aksoy C. O. An Updated Formula and Method to Predict the Performance of Impact Hammers. International Journal of Rock Mechanics and Mining Sciences. 2013. Vol. 61. pp. 289–295
42. Aksoy C. O. Proposed chart for the selection of impact hammer. International Journal of Rock Mechanics and Mining Sciences. 2014. No. 68. pp. 120–127.
43. Bolobov V. I., Le-Thanh B., Plaschinsky V. A. Crack propagation in rock upon impact. Obogashchenie Rud. 2019. No. 6. pp. 3–9.
44. Dvornikov L. T., Klishin V. I., Nikitenko S. M., Korneyev V. A. Experimental designs of a combined tool using superhard composite materials for effective destruction of mine rocks. Eurasian Mining. 2018. No. 1. pp. 22–26.
45. Evans I. Energy requirements for impact breakage of rocks. Proceedings of the Fluid Power Equipment in Mining, Quarrying and Tunneling. 1974. pp. 1–8.
46. Grantmyre I., Hawkes I. High-energy impact rock breaking. CIM Bulletin. 1975. pp. 63–70.
47. Mahyera A., McDonald R. C., Koenning T. H. Predicting performance of joy Heftiimpactors for secondary breaking. Proceedings of the 14^th Canadian Rock Mechanics Symposium, Vancouver, CIM Special. 1982. No. 30. pp. 59–63.
48. Sokolinsky V. B. Percussion machines. Moscow : Mashinostroenie, 1982. 185 p.
49. Stavrigin A. N., Tarasov B. G. Experimental physics and mechanics of rocks. Saint Petersburg : Nauka, 2001. 343 p.
50. Zelenin A. N. Fundamentals of disintegration of soils. Moscow : Mashinostroenie, 1968. 376 p.
51. Ushakov L. S., Kotylev Yu. E., Kravchenko V. A. Hydraulic percussive machines. Moscow : Mashinostroenie, 2000. 416 p.
52. Mattis A. R., Labutin V. N., Dmitriev V. D. et al. Excavating machine with bucket of active action, Novosibirsk : Nauka, 1996. 174 p.
53. Bilgin N., Copur H., Balci C. Mechanical excavation in mining and civil industries. Boca Raton : CRC Press—Taylor & Francis Group, 2014. 388 p.