IRANIAN JOURNAL OF MINING ENGINEERING (IRJME)
Year:2019 | Volume:14 | Issue:42 |Papers Count:8

Roasting methods due to environmental problems in the production of sulfur dioxide gas have led to further research on hydrometallurgy. In this research, the effect of effective acid leaching in the presence of oxidizing agents on sphalerite in the Aligudarz gol-zard mine was investigated. The purpose of this study is to recover acidic solution of zinc from sulfide raw ores using sulfuric acid and hydrochloric acid and the use of oxidants. In order to achieve the best operating conditions for further recovery, the parameters affecting the acid leaching process in the presence of oxides of hydrogen peroxide and potassium permanganate were investigated. Leaching in terms of acid concentration (0. 5-3. 5) molar, oxidizing materials concentration (0. 01-0. 05) volumetric, temperature (30-80° C), solid to liquid ratio (0. 01-0. 05) and stirring speed (300-800 rpm). During this process, the elemental produced sulfur was filtered, and also the zinc hydroxide was saparated by the addition of sodium hydroxide in the precipitation step by filtration. After the end of the research, sulfuric acid was observed with 3 molar concentration and 0. 05 oxidation of hydrogen peroxide at 50 ° C and solids to liquid 0. 01 and 700 rpm respectively. The optimum recovery of zinc solution was achieved in the optimum conditions and that the sulfuric acid oxidizing hydrogen peroxide was more efficient than hydrochloric acid and oxidizing potassium permanganate.

Pressure distribution and estimation methods of cover pressure distance in the goaf of longwall coal mines has always been challenging due to the inaccessibility of the waste area. When a longwall panel is excavated, the overburden strata are disturbed in order of severity from the immediate roof towards the surface. The immediate roof behind the longwall face collapses at a distance that changes depending on the properties of rock, the thickness of immediate strata, and on the type and nature of strata. To date, extensive attempts have been made for a comprehensive understanding of the stress and deformation state of the caved and fracture zone in horizontal working faces but research has been rare on steep coal seams. In the present study, stress and displacement redistribution and cover pressure distance in the longwall steep coal mines was analyzed by using the finite difference method and the result was compared with existing literature available. In general, displacement and stress redistribution template is in accordance with the previous research works. Depth, excavation height, bulking factor and compressive strength of the rock fragments is affecting cover pressure distance. Cover pressure distance was determined 198 m and it shows a close agreement with the literature. Support system evaluation was made by Sakurai’ s critical strain for underground excavations and tunnels and so the stope’ s lower part and the conveyance roadway were determined as critical locations.

In exploratory projects, the number of collected data is much smaller than the area of investigation, thus finding a robust tool for deposit spatial modelling that accords to the limited collected data is very important. According to the characteristics of the studied deposit, different geostatistical simulation algorithms were presented with the ability to generate different models of the deposits to solve this problem. The existence or absence of highly skewed exploratory collected data in study area is one of the reasons for using sequential indicator simulation method or sequential Gaussian simulation method. In this article, according to the type of study activities, graphical evaluation and review technique (GERT) programing network was used for exploration projects management and creation of a suitable pattern for use of sequential gaussian simulation and sequential indicator simulation. To implement the possible activities of the designed network, geochemical data of Dali Cu-Au porphyry deposit was used. Comparison results of SIS simulation on gold data (highly Skewed) with results of SGS simulation on copper data (lowly skewed) indicates the high correlation of these two elements and the existence of a Cu-Au porphyry deposit along the NE-SW direction in the northern Dali area. The adaptation of the survey results with geological evidences proved work steps.

The most common method for surveying discontinuities is the scanline method, which has the shortcomings of insufficient safety, number of measurements, and accuracy of measurement. Furthermore, determination of the block volumes generated by discontinuities and measurement of the geological strength index (GSI) are other issues in characterization of the rock mass mechanical properties. The Golgohar iron mine has encountered the above noted issues and the need for a sophisticated and accurate method for measuring discontinuities is inevitable due to the highly fractured walls in mine No. 1 with high risk of failure. . This paper aims to develop a new approach for measurement of the mean block volume, rock quality designation (RQD), and the geological strength index GSI of the rock masses. Thus, the geometric properties of discontinuities in the 14th bench of the Northwest wall in mine No. 1 were measured using the photogrammetric method. To determine the geometric properties of the discontinuities on the slope face, control points were marked on the rock face and photos were taken from the rock surface. Then, using 3DM CalibCam, 3D point clouds and 3D photos were generated. The measurements were used to create a discrete fracture network (DFN) model. To generate the DFN model, FracMan software was used, which ultimately led to the determination of the mean block size, GSI, the mean spacing of each joint set, and the RQD of the rock mass. Results showed that the mean block volume is 0. 13 m3, and the GSI was measured to be 65. In order to investigate the ability of the proposed method in measuring RQD and GSI, results of twenty eight core logs from geotechnical boreholes were used. This investigation showed that the results of proposed model are in good agreement with the measured ones.

The effect of loading rate on the failure mechanism of rock specimens has been considered in many rock engineering research works, and it has been shown that when the loading rate rises, the strength of rock specimens increses. İ n the present study, the effect of loading rate on the breakage process of pre-cracked specimens has been studied using numerical simulations. Extensive numerical simulations of uniaxial compression tests were made using RFPA2D code, and the effect of loading rate on the failure mechanism of pre-cracked specimens was investigated. Results of experimental tests showed that with an increase in the loading rate, the length of wing cracks in specimens decreases.

Evaluation of zone dispersed mineralization from blind mineralizations in active and inactive mines are the main challenges in mining geochemistry. In the past years, Different quantitative models have been presented for different types of mineralization using zonality traditional method. These methods have different disadvantages. In this research, a new model have been presented for detection of anomaly by integration of singularity and zonality methods in Baggolom (in Jebal-Barez region), then the obtained results were compared with results of zonality and fractal methods. 400 rock samples were taken from the studied area, and analyzed for Cu, Zn, Ag, Pb, Au, W, As, Hg, Ba, Bi with emission spectrometry. According to the zonality method if Pb*Zn/Cu*Ag>10, the anomaly is a blind mineralization. This method shows the depletion and enrichment of vertical zonality index in the area. The singularity of vertical zonality index (Pb*Zn/Cu*Ag) was mapped. Results showed that the northern part of this area is a blind mineralization and the copper anomaly in the center and southwest of the area is a zone dispersed mineralization. These results are in good agreement with the zonality method and previous researches in this area. The fractal method with the zonality index threshold of 398 showed the same results. This method do not need to access the database of copper porphyry deposits or comparison with other similar deposits.

Copper anode slime is a byproduct of electrolytic copper refineries which usually contains many valuable elements such as Au, Ag, PGMs (platinum-group metals), Cu, Se, Pb, As, and Sb. Anode slime is generally considered as the main source of the world’ s selenium and one of the important sources for the extraction of precious metals. Several methods have been used for processing and recovery of selenium from anode slime. One of the prevalent common industrial methods is sulfation roasting. In this research, the sulfation roasting method was optimized to recover selenium from copper anode slime whichthat is able to minimize the environmental pollutions and energy consumption. A D-optimal design based on response surface methodology was used for modeling of the roasting stage. The effect of two parameters was investigated on the roasting process; of liquid to solid ratio (L/S), and temperature on the roasting process was investigated. The selenium recovery was optimized and at the optimum condition of the L/S ratio of (1. 9 mL/g) and temperature of (247. 3 ° C), the selenium recovery was found to be 99. 99%. The head sample of the copper anode slime was characterized by x-ray diffraction (XRD), x-ray fluorescence (XRF), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The selenium purity was determined to be 97. 08 % by ICP.

In mining and metallurgical activities, wastewater must be treated before discharging into the environment because of high cyanide toxicity. One of the most effective technologies for cyanide removal is adsorption. In this research, layered double hydroxides (LDHs) known as anionic clays was synthesized by co-precipitation process using a 3: 1 ratio of magnesium nitrate and aluminum nitrate and used for removal of cyanide from aqueous solutions. The chemical and mineralogical compositions of LDH were investigated using XRD, XRF, Scanning Electron Microscopy (SEM), and Wavelength Dispersive X-ray (WDX) analysis. Particle size of LDH was determined to be about 4 nm using Scherrer equation which indicates that the synthesized LDH is in the range of nano-sized materials. The effects of temperature, adsorbent dosage, stirring speed, and pH on the adsorption capacity of LDH for cyanide were investigated using experimental design method (DX7 software). Maximum adsorption capacity of synthesized LDH for cyanide was obtained about 73. 80 mg/g at stirring speed of 500 rpm, 60oC temperature, adsorbent weight of 1. 5 g, and pH=9. 52. The equilibrium and kinetic data were best fitted by Langmuir isotherm and pseudo-second order model, respectively. The adsorption rate limiting step was determined to be intra-particle diffusion based on Weber and Morris model. It was found that the adsorption of cyanide onto LDH was occurred through ion-exchange mechanism, due to the chemical composition and mineralogical structure of anionic clay. Moreover, LDH was synthesized using industrial grade salt, and the results showed that with an adsorbent dosage of 20 g/l, more than 84% of the cyanide can be removed from a real wastewater, and LDH has the potential for cyanide removal from aqueous solution.