Scree formation on nonmining flank of an opencast and its impact on vegetation restoration

The purpose of the conducted research is to study the regularities of scree formation and assess their impact on self-vegetation of disturbed lands after mining of building stone deposits. The processes of natural formation of scree have been studied, their layering and gravitational alignment have been determined, the factors causing pit bench collapse have been identified. Simulation of the scree formation process allowed to establish the dependence of rock spreading distance on bench height, bench slope angles, as well as on the weight of individual pieces. The slope bench angles with the largest and smallest rock spread distance were found. The simulation showed the influence of the slope bench angles and parameters of the scree formed at the foot of pit benches on the range of debris spread. Three distinct formation stages of scree at the foot of the benches are identified. The angles of transition from one stage of scree formation to another are determined. Recommendations are given to improve the conditions of self-vegetation and minimize the negative factor of scree formation. To form a layer of loose sediments on horizontal bench sites it is proposed to use rocks from scree, which can dramatically reduce the cost of reclamation rather than imported man-made mixture or potentially fertile soils. In order to increase self-vegetation intensity on the flanks of opencasts, it is recommended to increase the bench height and berm width without changing the design angle of the opencast flank slope. To reduce the adverse impact of scree formation on vegetation restoration on the sides at the bench foot, it is proposed to form a trench collecting falling rocks or a rockprotecting wall.

Indirect Determination Approach of Blast-Induced Ground Vibration Based on a Hybrid SSA-Optimized GP-Based Technique

The accurate determination of blast-induced ground vibration has an important significance in protecting human activities and the surrounding environment. For evaluating the peak particle velocity resulting from the quarry blast, a robust artificial intelligence system combined with the salp swarm algorithm (SSA) and Gaussian process (GP) was proposed, and the SSA was used to find the optimal hyperparameters of the GP here. In this regard, 88 datasets with 9 variables including the ratio of bench height to burden (H/B) and the ratio of spacing to burden (S/B) were selected as the input variables, while peak particle velocity (PPV) was measured. Then, an ANN model, an SVR model, a GP model, an SSA-GP model, and three empirical models were established, and the predictive performance was evaluated by using the root-mean-square error (RMSE), determination coefficient (R2), value account for (VAF), Akaike Information Criterion (AIC), Schwarz Bayesian Criterion (SBC), and the run time. After comparing, it is found that the proposed SSA-GP yielded a superior performance and the ratio of bench height to burden (H/B) was the most sensitive variable.

PENGGUNAAN EXPLOSIVE LOW DENSITY PADA PELEDAKAN AREA DI BAWAH RADIUS AMAN MANUSIA DAN PENINGKATAN PRODUKTIVITY ALAT GALI DI AREA TERSEBUT PADA PENAMBANGAN BLOK B1 PIT C2 SAMBARATA MINE OPERATION PT BERAU COAL

ABSTRAK Pit C2, merupakan salah satu blok penambangan Site Sambarata Mine Operation yaitu masuk ke dalam blok B1. Merupakan pit aktif hingga sekarang dimana penambangan dari 2018 hingga akhir 2019 telah mengarah ke pemukiman hingga boundary pit (2019) berjarak 200 m ke pemukiman terdekat dan area tersebut penambangan menggunakan peledakan.Volume overburden pada area tersebut yang termasuk zona dibawah 500 m jarak aman peledakan adalah 1.340.281 bcm dan coal sebesar 175.237 ton dengan SR 7,65. Telah diterapkan beberapa taknik peledakan pada area tersebut ,yaitu salah satunya dengan sistem peledakan elektronik detonator dengan berbagai improvmentnya diantaranya : pola segementasi, segmentasi bufferzone, electronic detonator with air decking dan penggunaan matrial stemming full gravel. Kendala yang timbul adalah masalah efek peledakan yaitu vibrasi dan fly rock dengan jarak tersebut serta pembentukan bench height yang tidak maksimal karena adanya limit kedalaman lubang maksimal 5 m di area 500-300 m dari pemukiman, sehingga produktivity unit (PC 2000) tidak maksimal dan menimbulkan blasting cost yang tinggi. Penggunaan Explosives Low Density (0,7-0,8 gr/cc), di area < 500 m dari pemukiman bisa menambah kedalaman lubang bor hingga kedalaman 7 m, sehingga menambah volume peledakan tanpa mengubah parameter peledakan sebelumnya yaitu : pattern peledakan, charging weight dan penggunaan sistem elektronik detonator dan juga bisa menggunakan sistem peledakan nonel. Dengan explosive low density pengingkatan column raise lubang ledak menjadi 1,3 m. Dari data digging time unit loader (PC 2000), mampu mencapai 9,9 detik dari target maksimal 11 detik, produktivity di atas 700 bcm/jam dan vibration effect yang dihasilkan masih di bawah 2,2 mm/sec (PVS) yang menjadi patokan site. Sehingga penggunaan explosive low explosive ini bisa mempercepat sekuen penambangan di pit C2 sesuai dengan boundary disain 2019 Kata kunci : Low density,Ground vibration, fly rock , productivity ABSTRACT Pit C2, is one of the Mining Samntbarata Mine Operation mining blocks, which is included in Block B1. It is an active pit up to now where mining from 2018 to the end of 2019 has led to settlements to the boundary pit (2019) within 200 m to the nearest settlement and the area is mining using blasting. Overburden volume in the area which includes zones below 500 m safe blasting distance is 1,340,281 bcm and coal of 175,237 tons with SR of 7.65. Several blasting techniques have been applied in this area, one of which is an electronic detonator blasting system with various improvements including: Segmentation pattern, buffer zone segmentation, electronic detonator with air decking and the use of full gravel matrial stemming. The obstacle that arises is the problem of blasting effects namely vibration and fly rock with that distance and the formation of bench height that is not optimal because of the maximum hole depth of 5 m in the area of 500-300 m from the settlement, so the productivity unit (PC 2000) is not optimal and causes high blasting cost. The use of Explosives Low Density (0.7-0.8 gr / cc), in the <500 m area of the settlement can increase the depth of the drill hole to a depth of 7 m, thus increasing the volume of blasting without changing the previous blasting parameters namely: blasting pattern, charging weight and the use of an electronic detonator system and can also use a nonel blasting system. With explosive low density the column raising the explosive hole to 1.3 m. From the digging time unit loader data (PC 2000), it can reach 9.9 seconds from the maximum target of 11 seconds, productivity above 700 bcm / hour and the resulting vibration effect is still below 2.2 mm / sec (PVS) which is the benchmark site . So that the use of low explosive explosives can accelerate the mining sequence in pit C2 in accordance with the 2019 design boundary. Kata kunci : Low density,Ground vibration, fly rock , productivity

The Study of Parameters of Quarry Faces in Muruntau and Myutenbai Open Pits in Case of Applying Major Blasts

The paper presents process layouts for excavation of zones near pit envelope based on the analysis of findings of the ore loss study in case of open-pit mining, as well as the results of field measurements in the quarry faces in Muruntau and Myutenbai open pits. In the course of the field measurements, parameters of the quarry faces at Muruntau and Myutenbai open pits were determined under the following working conditions of an excavator: at full bench with shotpile height of 19–21 m; at full bench with shotpile height of 12–14 m at excavation of the “blast cap”; at heading face and taking ramp material. In all the above-listed quarry faces, the slope angles and the ore mass shotpile height when excavating were measured. Besides, the used excavator type (dragline or hydraulic) was taken into account. For each face, 2–3 measurements were performed, and the average slope angle at the ore mass excavation was determined for each type of excavator. At the next stage of the field measurements, the bench height in the rock mass and the shotpile parameters were measured before and after blasting operations under the following arrangements for preparing the rock mass for excavation: a) under normal conditions, when the ore mass blasting is performed for the selected face or relieving wall of the required thickness; b) in compression with a “blast cap” formation; c) in the marginal parts of the bench. Based on the results of the actual bench height and the blasted rock shotpile parameter field measurements, the following conclusions were drawn: a) the actual slope angles of the quarry faces were 49° when excavating the “blast cap” using dragline excavators, and 53° when excavating the ore mass at full bench regardless of the excavator type used; the slope angles of 49° for the dragline excavator and 53° for the hydraulic excavators were taken for further calculations; b) the width of the marginal (near-envelope) zone, where losses and dilution of balance ore are generated, increased from 7 to 13.0 m (at 49°) and from 7 to 11.3 m (at 53°); as a result, the areas of loss and dilution triangles have increased; c) when blasting in compression conditions, in the upper part of the shotpile, intense mixing of the involved rock and all ore grades occurs, therefore, when excavating the “blast cap”, bulk ore mass mining is only possible. The lower part of the blasted bench preserves the geological structure of the rock mass to a greater degree and can be selectively excavated with separation of the ore mass by grade; d) when blasting the rock mass, to maintain the required pulse direction and the blasting sequence, barren boreholes are included in the breaking outline, which increase the balance ore dilution, and structural dilution arises, which should be taken into account when drawing up the "Methods for determining, limitation and accounting for ore losses and dilution in the course of the Muruntau and Myutenbai (the fifth stage) open-pit mining"; e) when compiling the "Methods ...", the option of dividing a bench of 15 m high into two sub-benches of 7.5 m should be considered.

Technological Indicators of Direct Dumping Zone as a Part of Combined Mining Method

Under the conditions of a combined mining system overburden is developed using a transport and non-transport technologies, specific costs for non-transport technology are lower than transport costs. The change in the non-transport bench height led to the redistribution of the volumes of transport and non-transport overburden. With an increase in the volume of non-transport overburden, the share of more expensive transport overburden is decreases, while the technical and economic indicators of the non-transport zone deteriorate due to an increase in re-excavation volumes. The change in the non-transport bench height affects the recasting ratio and the annual advance coal face line, which determine the cost of developing the overburden. This article presents the results of a study of the laws of change in the recasting ratio and the annual advance coal face line, depending on the non-transport bench height within a combined mining system of flat seam. The obtained patterns were established as a result of solving problems of substantiating typical excavation schemes of the direct dumping method and developing a mathematical model for identifying excavation schemes with the subsequent calculation of their technological indicators.

Study of the Backhoe’s Digging Modes at Rock Face Working-Out

As is known from the classic works on open pit mining, the bench is a separately developed part of the rock layer, having the form of a step. It should also be noted that it is necessary to clearly differentiate the concepts of “bench height” and “height of the layer to be removed.” The benches are often divided into subbenches, developed by different excavation equipment or by the same equipment both sequentially and simultaneously, but having transport routes that are uniform for the bench. As an example, an excavator stripping of the upper and lower subbenches with loading, respectively, at the level of the excavator and above this level, is usually given, that is, the transport route (road) passes through an intermediate platform bench located in the middle of its height. Therefore, the excavation layer of any height, which is, in fact, a part of the working bench, can be considered as an independent bench with all its attributes, but in order to avoid duplication of definitions, this paper suggests the name “extraction layer”. When developing this element various digging modes can be applied. In this paper, we studied the main modes and selected the one that provides the highest performance.