A development in rock cutting technology

Hood, M.; Alehossein, Habib

doi:10.1016/s1365-1609(99)00107-0

Cited by 70 publications

(35 citation statements)

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“…The technology, from CRC Mining, is known as oscillating disc cutting (ODC) and is being commercialized by Joy Global under the tradename Dynacut, (Hood and Alehossein, 2000). The effect of adding a small oscillation with a frequency of 35 Hz to an undercutting disc is shown in the last column of Table III.…”

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confidence: 99%

A review of rock cutting for underground mining: past, present, and future

Vogt¹

2016

J. South. Afr. Inst. Min. Metall.

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Blasting is the dominant method of breaking rock for the purposes of mining. When used underground, blasting is part of a batch process. If rock can be cut rather than blasted, mining can become continuous, leading to process and efficiency improvements.Coal produced from underground mines is now predominantly excavated using mechanical means, but underground hard rock is still broken primarily by explosives.This paper traces the history of rock cutting, reviews the main physical processes that are or could be used, and comments on the future. It is written from the perspective of narrow-stope hard-rock mining typical of South African gold and platinum mines.This review is not definitive, but covers the most important experiences in rock cutting that are applicable to the South African hardrock environment, and discusses the future of practical techniques, as well as briefly examining some more speculative methods. The issue of the mining system is not a primary consideration -it is a topic for another paper.Rock cutting offers a number of advantages over drill-and-blast mining. Possibly the most significant is that cutting offers the opportunity for continuous operations. Blasting introduces a cycle into mining, which then forces a batch mode on the process: drill, blast, clean, support. Particularly on larger mines, where all blasting occurs at about the same time, the mining process must fit into the defined time between blasts. If the drilling, cleaning, and supporting take less than the allocated time, then time is wasted. If they take longer, then the next blast is missed. In both cases, the rigid timing leads to system inefficiency. The move to continuous processes is now considered the key to improved productivity in industry, as part of the Lean philosophy (Womack and Jones, 2003), and offers the same benefits for mining.Mechanical methods of tunnelling have the potential to be significantly faster than drilland-blast methods. In the context of mining, earlier access to the orebody considerably increases the net present value of the mine.Rock cutting has a number of other advantages:® In tunnelling and other applications that might be close to human settlements, cutting generates significantly lower vibration and noise levels than the use of explosives ® The cutting process affects the rock surrounding the excavation less than explosives, thus the rock stronger is and safer (or easier to support)A review of rock cutting for underground mining: past, present, and future by D. Vogt* Rock has been cut in the process of mining since before the invention of explosives. Today, we seek to return to cutting to reap the benefits of continuous operations for South African underground hard-rock mines, to improve speed of access to the orebody, and to improve the efficiency of mining operations. Development of new technology fits within a framework of engineering knowledge. By understanding the characteristics of the rock, the tools we use to cut it with, and the history of mining and rock cutting, we can see the g...

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A review of rock cutting for underground mining: past, present, and future

Vogt¹

2016

J. South. Afr. Inst. Min. Metall.

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“…The distinction between these two tool categories lies in their cutting actions. Specifically, as can be seen from Figure 2.1, a drag bit attacks the rock along a direction approximately parallel to the rock surface while a disc cutter generates rock breakage by pressing normally to the rock surface [2,28].…”

Section: Rock Cutting Mechanismmentioning

confidence: 99%

“…These machines offer many advantages such as high productivity, better reliability, ease of automation as well as being environmentally friendly. Additionally they allow for continuous and selective mining, controllability of the chip sizes and safer operations in comparison with the conventional drill & blast technique [1][2][3][4][5]. Open pit and underground coal mining are now carried out by mechanical excavation machinery such as surface miners, longwall shearers (Figure 1.1) and continuous miners (Figure 1.2).…”

Section: Introductionmentioning

confidence: 99%

“…Open pit and underground coal mining are now carried out by mechanical excavation machinery such as surface miners, longwall shearers (Figure 1.1) and continuous miners (Figure 1.2). These mechanical excavation machines usually cut rock/coal with an array of picks installed at specific intervals, spacing and attack angles on a rotating drum or cutterhead [2]. There are two main categories of drag bits employed on underground mining machines (Figure 1.3), radial and point attack/conical picks.…”

Section: Introductionmentioning

confidence: 99%

“…However, the major challenges that limit the use of mechanical machinery in hard rock mining are: (a) excessive abrasive wear of traditional refractory carbides based cutting element, (b) the considerable respirable dust generation and (c) the occurrence of frictional ignition [2,8,15,16,[20][21][22][23][24][25][26]. A large number of researchers have begun to address these issues and to extend the capability of the mechanical excavation machines for high strength rock.…”

Section: Introductionmentioning

confidence: 99%

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A study of rock cutting with point attack picks

Shao¹

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Hard rock mining is currently carried out by drill-and-blast. With the increasing demand for automated, selective and remote mining, the industry hopes to replace conventional drill-and-blast with mechanical excavation. Modern mining machines have sufficient power for cutting hard rocks.The 'bottleneck' which limits the use of mechanical excavation for hard rock mining is the cutting tool wear. Rock cutting tools usually use tungsten carbide (WC) tipped picks. The WC tipped picks are effective and adequate for cutting relatively soft rocks, but unsuitable for hard rocks. To address this issue, CSIRO has developed Super Material Abrasive Resistant Tool (SMART*CUT), aiming at providing an effective cutting tool for hard rock mining. The key feature of the SMART*CUT technology is replacing the conventional WC with thermally stable diamond composite (TSDC) as the cutting tip of the pick. The main advantages of the TSDC tipped picks include (a) good thermal stability, (b) high wear resistance and (c) the ability to mine relatively hard deposits in comparison with the WC tipped picks. The disadvantage of the TSDC tipped picks is their low fracture toughness. To optimise the application of the TSDC tipped picks, this work aimed to improve the understanding of the rock cutting process and mechanisms, in particular to gain a better insight into the interaction between tools and rocks through systematic experimental and numerical studies. The rock cutting processes with the TSDC and WC tipped point attack picks were comprehensively investigated in terms of cutting force, specific energy, tool tip temperature and cutting chips.A study of rock cutting was systematically carried out using the Taguchi method to determine the effects of the cutting parameters on the performance of the TSDC tipped picks. The signal-to-noise (S/N) ratios and the analysis of variance (ANOVA) were applied to investigate the effects of the depth of cut, attack angle, spacing and cutting speed on the mean cutting, normal and bending forces involved in the rock cutting process. The statistical significance of process factors was determined and the optimum parametric combinations were successfully identified. Furthermore, the multiple linear regression (MLR) and artificial neural network (ANN) techniques were adopted to develop the empirical models for predicting the mean cutting and normal forces with the TSDC tipped picks. The established empirical force models showed good predictive capabilities with acceptable accuracy. The ANN models offered better accuracy and less deviation than the MLR models.The pick cutting temperature involved in rock cutting was measured using thermal infrared imaging and embedded thermocouple techniques. The temperature distribution in the cutting area was acquired by using a thermal infrared camera with high speed imaging rates. The results showed that II the TSDC tipped picks generated much lower thermal energy and much fewer sparks than the WC tipped picks. The temperature at the pick tip in the contact area wi...

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Numerical simulation of the fracture process in cutting heterogeneous brittle material

Liu

Kou

Lindqvist

2002

Num Anal Meth Geomechanics

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SUMMARYThe process of cutting homogeneous soft material has been investigated extensively. However, there are not so many studies on cutting heterogeneous brittle material. In this paper, R-T 2D (Rock and Tool interaction), based on the rock failure process analysis model, is developed to simulate the fracture process in cutting heterogeneous brittle material. The simulated results reproduce the process involved in the fragmentation of rock or rock-like material under mechanical tools: the build-up of the stress field, the formation of the crushed zone, surface chipping, and the formation of the crater and subsurface cracks. Due to the inclusion of heterogeneity in the model, some new features in cutting brittle material are revealed. Firstly, macroscopic cracks sprout at the two edges of the cutter in a tensile mode. Then with the tensile cracks releasing the confining pressure, the rock in the initially high confining pressure zone is compressed into failure and the crushed zone gradually comes into being. The cracked zone near the crushed zone is always available, which makes the boundary of the crushed zone vague. Some cracks propagate to form chipping cracks and some dip into the rock to form subsurface cracks. The chipping cracks are mainly driven to propagate in a tensile mode or a mixed tensile and shear mode, following curvilinear paths, and finally intersect with the free surface to form chips. According to the simulated results, some qualitative and quantitative analyses are performed. It is found that the back rake angle of the cutter has an important effect on the cutting efficiency. Although the quantitative analysis needs more research work, it is not difficult to see the promise that the numerical method holds. It can be utilized to improve our understanding of tool-rock interaction and rock failure mechanisms under the action of mechanical tools, which, in turn, will be useful in assisting the design of fragmentation equipment and fragmentation operations.

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A development in rock cutting technology

Cited by 70 publications

References 3 publications

A review of rock cutting for underground mining: past, present, and future

A review of rock cutting for underground mining: past, present, and future

A study of rock cutting with point attack picks

Numerical simulation of the fracture process in cutting heterogeneous brittle material

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