Dimension-stone quarrying optimization is significantly important to increase the recovery ratio of dimension stone and to reduce the cutting cost. Due to fracture-existed rock mass, in the mining operation block size and mining direction influences to the recovery ratio and the cutting cost. Therefore, the paper suggests the quarrying optimization for dimension stone to obtain the highest recovery ratio and the lowest cutting cost, based on optimizing block size and mining direction to get a cutting grid of dimension stone. Through developing an integrated modelling between joint set modelling and cutting grid modelling, intact blocks and fractured blocks were generated. From this, block statistics were conducted to get the maximum recovery ratio of dimension stone and the minimum cutting rate between the cutting area and the recovered block volume, which helps to choose an optimizing block size and mining direction. The research was carried out at Tan Long dimension stone quarry where a block size (0.9m x 0.6m x 1.35m) and a mining direction paralleling to joint set 1 will ensure the highest recovery ratio of 13.87% and the lowest cutting rate of 25 m2/m3.
In surface mining operations, the operating costs of truck-shovel system constitutes 50-60% of the total. Only a little save in the operation costs in this system will bring large profit for the mines. Due to many investment periods, the capacity of both trucks and shovels in Cao Son surface coal mine is different. This leads to the low efficiency and the difficulty in dispatching strategy for the mine. This paper presents the current situation and selection of advanced dispatching strategy for increasing the efficiency trucks and shovels at this surface coal mine. The results show the detailed match factor reflects the state of each team of loader and trucks and should be use as the indicator for dispatching decision for the heterogeneous truck and shovel fleet at Cao Son surface coal mine.
The prediction of fly-rock distances is a big problem in the blasting areas of open-pit mines. The fly-rock distance plays a crucial role in the reduction and control of blasting accidents in quarries. This paper proposes the modelling of the contact dynamics as a non-smooth discrete element method (NSCD). Then, the fly-rock phenomenon is simulated using this NSCD method. This approach was to develop a model that correlates to blast conditions, initial fly-rock/rock-fall velocities and permits the computation of fly-rock range from randomization orbits. The results showed that the NSCD method is a good means for the simulation with the variability of blasting parameters. This method is to relate the initial fly-rock velocity to blast conditions and then uses ballistic trajectories to compute the maximum fly-rock distance. Finally, it should be noted that the proposed simulation of fly-rock trajectories which shows the distribution of fly-rock bounce heights above the ground level with the different coefficient of restitution range as a function of blast conditions. It should be used in the Ninh Dan limestone quarry belonging to the Song Thao Cement, Phu Tho province (Vietnam), and it should be directly used in the same other quarries.
PL
Przewidywanie odległości między odrzucającymi skałami ma duży problem w kopalniach odkrywkowych. Odległość między skałami odrzucającymi odgrywa niezwykłą rolę w ograniczaniu i kontrolowaniu wypadków spowodowanych robotami strzelniczymi w kamieniołomach. W artykule, zaproponowano modelowanie dynamiki kontaktu jako metodę elementów dyskretnych Non-Smooth (NSCD). Następnie symuluje się zjawisko fly-rock metodą NSCD. Zastosowane podejście polegało na opracowaniu modelu, który kore-luje warunki wybuchów, początkowe prędkości lotnych skał i pozwala na obliczenie zasięgu fali z orbity losowej. Wyniki pokazały, że NSCD jest dobrym środkiem do symulacji przy zmienności parametrów strzałów. Ta metoda zastosowana w niniejszych badaniach polega na powiązaniu początkowej prędkości latających skał z warunkami wybuchu, a następnie wykorzystaniu trajektorii balistycznych do obliczenia maksymalnej odległości między latającymi skałami. Na koniec należy zauważyć, że zaproponowano symulację trajektorii odrzucających skał, która pokazuje rozkłady wysokości odbijania skał nad poziomem ziemi przy różnym współczynniku zakresu restytucji w funkcji warunków techniki strzelniczej. Powinien być stosowany w kamieniołomie wapienia Ninh Dan należącym do cementu Song Thao w prowincji Phu Tho (Wietnam) i powinien być stosowany w podobnych kamieniołomach.
In dimension stone extraction, there have existed many block cutting techniques from intact rock or from a large block to smaller blocks such as disc sawing, chainsawing, diamond wire sawing and splitting techniques, one of which still has recently been used with the other modern methods is splitting techniques. The usage of the splitting methods has still based on the practical experience of mining workers on calculating the spacing of two holes in the co-planar line, resulting in increasing the roughness of the cutting face. The paper studies a relationship between beating force and two-hole spacing based on rock mass properties of dimension stone in order to find proper splitting parameters. The paper deploys the Finite Element Method (FEM) with computer simulation in 2D using Phase2 software. From input data including rock mechanics (unit density, Young’s modulus, Poisson’s rate), compressive pressure on the hole wall due to the force, the spacing, the simulation represents stress and displacement distributions along the two adjacent holes. A regression function for a relationship between the pressure and the spacing is established with the results of stress distribution along the two adjacent holes, compared to uniaxial tensile strength through running the software, which leads to making suggestions to appropriate splitting parameters.
PL
W zakresie wydobywania złoża kamieni blocznych istniało wiele technik cięcia bloków, od nienaruszonej skały lub od dużych bloków do mniejszych bloków, takich jak piły tarczowe, piły łańcuchowe, piły diamentowe i tech-niki łupania, z których jedna jest ostatnio używana z drugą nowoczesną metody to techniki dzielenia. Stosowa-nie metod łupania nadal opiera się na praktycznym doświadczeniu górników przy obliczaniu rozstawu dwóch otworów w linii współpłaszczyznowej, co skutkuje zwiększeniem chropowatości czoła skrawania. W artykule zbadano zależność między siłą uderzenia a rozstawem dwóch otworów na podstawie właściwości górotworu kamieni blocznych w celu znalezienia odpowiednich parametrów rozłupywania. W artykule zastosowano meto-dę elementów skończonych (MES) z symulacją komputerową 2D przy użyciu oprogramowania Phase2. Na pod-stawie danych wejściowych obejmujących mechanikę skał (gęstość jednostkowa, moduł Younga, współczynnik Poissona), ciśnienie ściskające na ścianę otworu spowodowane siłą, rozstaw, symulacja przedstawia rozkłady naprężeń i przemieszczeń wzdłuż dwóch sąsiednich otworów. Na podstawie wyników rozkładu naprężeń wzdłuż dwóch sąsiednich otworów, w porównaniu z jednoosiową wytrzymałością na rozciąganie po uruchomieniu oprogramowania, ustala się funkcję regresji zależności między ciśnieniem a rozstawem, co prowadzi do sugestii dotyczących odpowiednich parametrów rozłupywania.
With many types of trucks and shovels for hauling large volume of waste rocks to the dump sites and coal to the storages, the truck – shovel dispatching in Cao Son open pit coal mine is the operation which needs to be improved. At present, the combination between trucks and shovel is usually assigned at the beginning of shift and adjusted during the operation at the mine. The GPS tracking system are integrated into each truck to monitor the position in real time, but applying this information to find the best destination to send the truck to satisfy the production requirements and to minimize truck operating costs is still not used. This paper presents the estimation of the information system, data, the remaining problems of truck – shovel dispatching system, from that proposes the application of available information technology for increasing the efficiency of this activities at the mine.
In dimension stone quarry exploitations such as the marble quarry, a literature review of the existing numerical modelling techniques has been carried out. According to Distinct Element Method, discontinuities have been treated as boundary conditions between blocks and, consequently, an accurate knowledge of joint distribution and orientation was required. The result of analyzing data and simulating in the fracture rock environment, which is applied to a mining condition of the dimensional stone quarries. The research we introduce in the output capacity of the dimension stone quarry from the computer simulations to generate the fracture network in 3D with an aim of evaluating the size of the blocks. The results of numerical models have been used to optimize some of the technical parameters for dimensional stone extraction and ensuring stable bench in the mining operation.
Air overpressure (AOp) is one of the products of blasting operations in open-pit mines which have a great impact on the environment and public health. It can be dangerous for the lungs, brain, hearing and the other human senses. In addition, the impact on the surrounding environment such as the vibration of buildings, break the glass door systems are also dangerous agents caused by AOp. Therefore, it should be properly controlled and forecasted to minimize the impacts on the environment and public health. In this paper, a Lasso and Elastic-Net Regularized Generalized Linear Model (GLMNET) was developed for predicting blast-induced AOp. The United States Bureau of Mines (USBM) empirical technique was also applied to estimate blast-induced AOp and compare with the developed GLMNET model. Nui Beo open-pit coal mine, Vietnam was selected as a case study. The performance indices are used to evaluate the performance of the models, including Root Mean Square Error (RMSE), Determination Coefficient (R2), and Mean Absolute Error (MAE). For this aim, 108 blasting events were investigated with the Maximum of explosive charge capacity, monitoring distance, powder factor, burden, and the length of stemming were considered as input variables for predicting AOp. As a result, a robust GLMNET model was found for predicting blast-induced AOp with an RMSE of 1.663, R2 of 0.975, and MAE of 1.413 on testing datasets. Whereas, the USBM empirical method only reached an RMSE of 2.982, R2 of 0.838, and MAE of 2.162 on testing datasets.
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