Experience of metal deposits combined development for South African enterprises

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Purpose. The improvement of hole drilling for increasing the mineral recovery ratio by ore drawing improvement through blasting.Methods. The drilling parameters were examined for rock dumps. The means of experimental drilling are drilling rig SKB-4; drill rods with a diameter of 42 mm and a length of 1.2 m; polyethylene pipes PND 63×8 and PND 70×8 with a length of 1.2 m; steel couplings for polyethylene pipes connecting; cone bits and RKS cutters. The criterion of drilling efficiency was the mechanical drilling speed. The drilling speed at different depths was measured with an axial force of 800 -2000 kg and rotational speeds of 120, 200 and 280 rpm. Experimental drilling was carried out using the charges of two modifications. 18 experimental boreholes with a length of 300 m were drilled.Findings. The article confirms possibility and practicability of simultaneous hole drilling and pipe casing without transmitting torque loads on the pipes and offers a design of a drill string with hoses inside drill rods and their further pulling up, and piping with simultaneous drilling. The scheme of interaction of blastholes and pipe casing when hole boring in broken ores is made. The nature of the relationship between the speed of penetration of vertical and horizontal holes with the change in the axial force and their length for different modifications of the drilling tool is studied.Originality. The new laws of change in the hole drilling penetration speed depending on the complex of technological parameters of drilling are obtained. The authors offer a model describing the possibility of hole drilling in the broken massif as well as an optimized design of the string necessary for that. Practical implications.The obtained regularities determine mechanical and energy drilling indexes and which are necessary at the stage of designing when deciding upon practicability of extraction of in-situ left ores while enhancing mining technologies of ore drawing.

Section: Resultsmentioning

confidence: 99%

Improvement of hole drilling technology for ore drawing intensification

Голик¹,

Morkun²,

Morkun³

et al. 2018

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“…We differentiate ( 6) by (n + 2) times and substitute it into (5). Equating the factors of the same power t, we obtain the equations for determining any factor yi applying m terms of the series:…”

Section: Figure 1 Adaptive Control System Of Drillingmentioning

confidence: 99%

Adaptive control of drilling by identifying parameters of object model under nonstationarity conditions

Morkun¹,

Morkun²,

Tron³

et al. 2020

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The research is intended to investigate and synthesize adaptive control over drilling by identifying parameters of an object model under non-stationarity conditions. Methods. Under conditions of rapidly changing borehole drilling indices, a two-level adaptive control strategy is applied, combining investigation of drilling and its control. The structure of the control system includes an additional block of forming the model on the basis of data on indirect features. Findings. The research develops a method for seeking the extremum developed for the object whose dynamics is described by a first-order linear differential equation. The method allows to determine the value of the output signal by evaluating the initial phase of the transient process caused by the changed input signal for a set step. Originality. The suggested algorithm of noise-free identification makes it possible to assess the factor of the control object transfer under the action of random disturbances. The data obtained is used to adjust the gain factor of the controller in the closed loop automatic control system of drilling. Practical implications. The suggested structure and algorithm of drilling control allow enhancing drilling efficiency by ensuring relevant mechanical drilling rates through defining corresponding rotation speeds and axial loads of a drilling tool.

“…In such a way, the analysis results lead to a conclusion that an important issue for solving the problem is the formation of technogenic cavities that affect the emergence and redistribution of the rock mass SSS. Their occurrence in the earth's crust provokes the influence of geomechanical and seismic phenomena, up to the earthquakes [17]- [20].…”

Section: Introductionmentioning

confidence: 99%

Substantiation of mining-technical and environmental safety of underground mining of complex-structure ore deposits

Lyashenko¹,

Andreev²,

Dudar³

2022

Purpose. Substantiation of mining-technical and environmental safety of underground mining of complex-structure ore deposits based on the study of a rock mass stress-strain state (SSS), as well as determining the safe parameters of stopes for specific mining-geological conditions and patterns of rock pressure propagation in various environments. Methods. To assess the improvement of mining-technical and environmental safety of mining operations, the research includes theoretical generalizations with the use of mathematical statistics, physical and mathematical modeling, performing calculations, as well as technical and economic feasibility, laboratory and full-scale experimental studies, industrial tests in mine conditions and on the earth's surface in the zone of blasting influence, based on the standard and new methods. Findings. A functional interrelation between the rock mass SSS value and the number of impulses (destruction sounds) per minute, characterizing its structural (а) and strength (b) properties, is proposed, which is described by a curvilinear dependence of the type y = axb and allows to quickly determine the stable parameters of stopes. Assessment and prediction are made for various forms of rock pressure manifestation, based on the stress concentration coefficient within 0.91 Kv 0.70, taking into account the conditions of the elastic behavior of rocks. The value of = 0.0002-0.0003 is taken as permissible relative deformation, which ensures both mining-technical and environmental safety, as well as the rock mass stability during repeated blasting operations. Originality. A classification of the rock mass SSS has been developed depending on the direction of the maximum stresses relative to the mine working location, the level of the rock mass stress state and the mechanism of rock pressure manifestation (η), as well as the category of rock-bump hazard. In particular, the rock mass with the values in the range oof 0.12 < η ≤0.2; 0.2 < η ≤ 0.3; 0.3 < η ≤ 0.5 and η > 0.5 are classified as non-rock-bump hazardous and belong to III, II, and I hazard categories, respectively. Practical implications. To substantiate the safe parameters of stopes based on the results of multi-year research into underground mining of complex-structure deposits, depending on the rock mass properties, a graphical-analytic method (nomographic charts and calculation formulas) is recommended. These parameters are determined for highly fractured, medium fractured and weakly fractured rock mass with its horizontal outcropping to the surface. Using this method, the Instruction on the Geomechanical Substantiation of the Safe Mining of the Reserves at the Skhidnyi Hirnycho-Zbahachuvalnyi Kombinat, DP (SE VostGOK), Ukraine, has been developed.