IRANIAN JOURNAL OF MINING ENGINEERING (IRJME)
Year:2019 | Volume:13 | Issue:41 |Papers Count:10

A majority of mined chromite ore is in form of fine particles (-200 μ m) which are difficult to be concentrated using gravity separation methods. On the other hand, these particles are required to be recovered in order to ensure process profitability and reduce environmental impacts. Slon high gradient magnetic separator is capable of processing paramagnetic particles. In this paper, the possibility of recovering chromite fine particles using a laboratory scale Slon high gradient magnetic separator is investigated. The effect of variables including magnetic field intensity, particle size, matrix size, and pulsating frequency was studied using the design of experiments. Results indicated that grade of concentrate part decreased when using a higher intensity magnetic field. Furthermore, with a rise in pulsating frequency and a reduction in the matrix size, the grade of concentrate part was increased. It was found that a concentrate grade of more than 40%, with a recovery of 65-90% is achievable using Slon magnetic separator. . Thus, it was concluded that the processing of fine chromite ore particles is technically viable using this method.

Coastal Fars Fields contains enormous amounts of hydrocarbons especially in form of gas and condensate (some oil). Petroleum system and sedimentary basin modeling is a cheap and useful method for reducing uncertainties in exploration costs and risks of drilling wells. In this study, using geological data, Rock-Eval 6 analysis and 1D basin modeling by Petromod version 11 and 12 software, the probability of Sarchahan formation and shaly sections of Kangan formation to produce two hydrocarbon fields in the Coastal Fars. Results showed that the Sarchahan formation is the original source rock of this area which reached a maximum burial depth of around 1. 6 to 1. 9 M. a, and produced around 2 million tons of hydrocarbon; Results also showed that shaly sections of Kangan formation produced a little amount of hydrocarbon but not as much to be the source of enormous amounts of hydrocarbon in this region.

One of the most important and challenging issues regarding underground spaces such as tunnels and caverns, is to estimate the amount of water entering to an underground space. A real estimation of the leakage is a very influential factor in the success of a project performance. Hydraulic conductivity can play a significant role on subsurface water flow. Lugeon and Lofran tests are routinely used to estimate hydraulic conductivities. In this study, distinct fractured network was employed to evaluate hydraulic conductivity. For this purpose, preprocessing was initially carried out on the data collected on the joints. These joints were divided into three groups of sub-horizontal, sub-vertical and bedrock joints. Afterwards, Poisson, exponential and logarithmic distributions were considered. A proper distribution for the joints was obtained using the exponential distribution with the highest agreement. Taking into account the initial conditions of the model, the DFN of the joints was created by 3DEC software. In the process of solving the problem, the DFN was considered with different eliminating filters, among which a 6-meter filter was selected as the appropriate one for removing the small fractures. DFN was validated using Watson & Williams test results and P-value test. The construction of the Representative Elementary Volume model was performed by using the 7 meters blocks. It is the optimum dimension describing the area, properly. Finally, results were verified with the data obtained from the Lugeon test; showing a relatively high correlation.

Investigation of behaviour of non-persistent joint is important in rock structure stability. This leads to improvement in rock engineering project design. Rock bridges in non-persistent joint increase shear strength of failure surface. For investigation of shear behaviour of rock bridges, 24 gypsum samples with dimension of 10 cm × 10 cm × 5 cm were prepared. The joint lengths in various samples are different but in the one sample the joint length are similar. Joint lengths change from 1 cm to 4 cm. in each joint length, joint angularity was 0, 15, 30, 45, 60, 75 degrees. These samples were under uniaxial compression test. The results show that failure pattern was affected by joint length, joint angularity and rock bridge length while failure load was controlled by failure pattern. Concurrent with experimental test, numerical simulation was performed using PFC2D software. The joint lengths in numerical model change from 1cm to 4 cm with increment of 1cm. In each joint length, the joint angularity is 0° and 45° . Failure pattern in numerical model was similar to experimental sample while failure load in numerical model was more than experimental outputs.

: In underground stopes, unplanned dilution occurs due to the over-break and slough of walls and roof, consequently mixing the ore with wastes. This phenomenon not only leads to a reduction in the grade, but also imposes some costs due to the grade deficit, and wastes money and energy for extraction of wastes. Hence, measuring the over-break and slough of roof and walls of the stopes is considered critical in underground mining, in order to determine the unplanned dilution and the study of its economic side-effects. In this paper, the effects of unplanned dilution on grade reduction, mining costs increase, and profit reduction was investigated using the cavity monitoring system (CMS). The system was implemented on 24 stopes of Venarch manganese mines, defining the linear equivalent of over-break and slough (ELOS) for the dilution, which led to understand the relations between the over-break and dilution parameters and the economic parameters, including the equation for predicting the loss of profit. Results of data analysis indicated that the break-even of the over-break was 2. 18 m that caused a dilution of 67. 38%; any further over-break will be loss-making.

Various methods have been proposed to determine the ultimate pit limits. Artificial intelligence-based methods such as heuristic genetic algorithms, ants and colony competition algorithms. Artificial bee colony (ABC) algorithm is one of the most powerful heuristic algorithms inspired by the social life of bees. In this paper, a hypothetical example of the life of bees is primarily described to find the source with the highest amount of nectar by this algorithm. Then, a method based on the bee algorithm is proposed to determine the ultimate pit limit, and to examine its performance, a two-dimensional example is described step by step. In this example, it was found that in cases where the moving cone can not find the optimal ultimate pit limit, the ABC method is well suited for introducing solution. Then, this algorithm was used to determine the ultimate limits of Sungun Copper mine pit with a number of 120*100*45 blocks. To validate the proposed algorithm, the graph theory and moving cone techniques were used. Results showed that the profit obtained by ABC algorithm is just 1. 6% less than that of graph theory algorithm, which is a rigorous technique and entails finding the true optimum. Meanwhile, the ABC algorithm provides 12. 3% more profit when compared to heuristic moving cone algorithm.

Due to the lack of a criterion such as grade, it is difficult to decide for the extraction of a stone quarry. On the other hand, the goal of optimization in quarries is to produce blocks in shapes of standard rectangular cuboids. In this research, an index is defined called Cubic Productivity Ratio (CPR) that classifies the quarries in terms of the geometric grade of the blocks into three categories: good, moderate, and poor. In addition, by applying cutting planes and comparison of CPR values for different directions, the optimum cutting direction can be determined. This index was implemented in Ask Travertine Quarry, Mazandaran Province, Iran, and its value was calculated to be 22%, which places the quarry in a poor level in terms of block geometric quality. The optimal direction was found at N60w, indicating that in order to get the most yield, the current direction should be adjusted 35 degrees to the north. With that being done, the average volume of blocks will be 241. 63 cubic meters, the average dimensions of the cuboids will be 2. 93 (m) × 2. 4 (m) × 2. 25 (m), and the amount of marketable cuboids will be 53369. 14 cubic meters, which will result in a revenue of about 130 billion IRR, according to the current sales price of raw blocks.

Germanium as a strategic element is found in aqueous solutions of various mining industries. For selective separation of germanium from an aqueous solution containing anionic complexant, tartaric acid, solvent extraction and supported liquid membrane (SLM) were used with Aliquat336. Affecting parameters such as extractant concentration, complexant type and concentration, and the concentration of the stripping phase containing hydrochloric acid, were investigated in the solvent extraction system. According to the results, germanium extraction efficiency rose up to 100% by increasing the concentration of Aliquat336 by 0. 2 %v/v. In addition, tartaric acid was found to be the best anionic germanium complexant. With the addition of 0. 275 mM tartaric acid, germanium extraction efficiency reached almost 99%. The highest stripping efficiency (99%) was achieved at the HCl concentration of 2 M. In the SLM system, 5 %v/v of Aliquat336 as a carrier was sufficient to transport 99% of germanium in the feed to the strip phase. Comparing two systems, the transfer time of the membrane system (510 min) is higher than that of the solvent extraction system (15 min).