فصلنامه مهندسی معدن
پیاپی 42 (بهار 1398)

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.

Since in exploratory works the number of collected data are much smaller than area of the study area therefore finding a strong tool for deposit spatial modelling with according to limited collected points is very important. According to study deposit characteristics different geostatistical simulation algorithms are presented with the ability to generate different models of deposits for the solution of this problem. The existence or absence of high skewness of 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 of programing network graphical evaluation and review technique (GERT) for explorative projects management and creation a suitable model in use of sequential gaussian simulation and sequential indicator simulation were used. For implement the possible network activities used of geochemical data of Dali Cu-Au porphyry deposit. Comparison of SIS simulation results on gold data for high Skewness with results of SGS simulation on copper data for low skewness indicates correlation top of these two elements is the existence of Cu-Au porphyry resource along the NE-SW in in Dali area. The results adaptation of the survey method with geological evidence proved work steps.

The most common method for surveying of discontinuities is the scanline method which has the shortcomings of low safety, low number of measurements and low 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 with the above noted issues and due to highly fractured walls of mine No. 1 with high risk of failure, the need for a sophisticated and accurate method for measurement of discontinuities is inevitable. 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 rock masses. To this end, the geometric properties of discontinuities in the 14th bench of the Northwest of 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 prepared from the rock surface. Then, using 3DM CalibCam, 3D point clouds were generated and 3D photos were generated. The measurements were used to create a discrete fracture network (DFN) model. To generate the DFN model, FracMan software were 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 of this study showed that the mean block volume is 0.13 m3 and the GSI were measured 65. In order to investigate the ability of proposed method in measurement of 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 crack behavior study in various rock types containing artificially created flaws under the quasi-static loading condition has been extensively studied in the past research works. However there are lacks of basic information regarding the failure mechanism of rock specimens under the dynamic loadings. Loading rate fundamentally influences on the strength and failure mechanism of rock specimens. In the present study, effect of loading rate on the crack propagation and failure mechanism of specimens containing with five different crack density numerically considered using RFPA2D code. For this purpose, specimen for modeling of uniaxial compression test with 54 mm in diameter and 110 mm in length was simulated. The geo-mechanical properties required for modeling have been derived from some experimental tests which are conducted on Granite specimens. The failure mechanism of simulated specimens was evaluated in three loading rates (0.002, 0.02 and 0.2 mm per steps). The effect of loading rate on the pre-crack growth and failure mode of specimens was considered. Regardless of the loading rate, in the first stage of loading sequences wing cracks initiate from the tips of the pre-existing cracks and tend to propagate parallel to the loading direction. Then secondary cracks usually initiated from tips of the wing cracks. Eventually, the propagation and coalescence of cracks resulted in unstably collapse of specimens. With increasing the loading rate the length of wing cracks decreases so that no wing crack created at loading rate of 0. 2 mm per step. It is shown that the failure modes of specimens under quasi-static compression loading is dominantly diagonal, while the failure mode under dynamic compression loading is “X” shape. This is because with increasing of loading rate to 0.2 mm per step, some second co-planar cracks formed at the tip of the main cracks.

Detection of zone dispersed mineralization from blind mineralization are the main target in mining geochemistry. Quantitative models for different types of mineralization have been presented byzonality method, in 40 years ago. zonality method has a disadvantages for detection of anomalies. In this research a new model was presented for detection of anomaly by integration of singularity and zonality methods. This Singularity method show the depletion and enrichment of vertical zonality index in study area. Singularity of vertical zonality index (Pb*Zn/Cu*Ag) was mapped in Baggolom which located in Jebal- Barez. The results were compared with fractal and zonality methods. For this purpose, 400 sampled were taken from systematic sampling grid. The samples were analyzed for Cu, Pb, Zn, Ag, Mn, Cr, Ni, Mo, Sn, V, Co, Ba, Sb, As, Bi, Hg and Sb by the atomic absorption method. According to the zonality method if Pb×Zn/Cu×Ag >10 anomaly is blind and α

Copper anode slimes are 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 silmes 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 slimes. One of the prevalent industrial methods is sulfation roasting. In this research, the sulfation roasting method was optimized to recover selenium from copper anode slimes that is able to minimize the environmental pollutions and energy consumption. D-optimal design based on response surface methodology was used for modeling of the roasting stage. The effect of the two parameters of liquid to solid ratio and temperature on the roasting process was investigated. The selenium recovery was optimized and at the optimum condition of L/S of 1.9 mL/g and temperature of 247.3 °C, Se recovery was found to be 99.99 %. The head sample of the copper anode slimes 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.

The wastewaters of the mining and metallurgical activities must be treated before discharging into the environment due to the highly toxicity of cyanide. One of the most efficient technologies for the removal of cyanide from wastewaters 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 and Scanning Electron Microscopy (SEM) and Wavelength Dispersive X-ray (WDX) analysis methods. The largest particle size of LDH was determined about 4 nm using Scherrer equation which indicates that the synthesized LDH is in the range of nano-sized materials. The effect of temperature, absorbent dosage, stirring speed and pH on the adsorption capacity of LDH for cyanide was investigated using experimental design method by DX7 software. The optimum conditions were determined to be temperature=60oC, adsorbent weight=1.5 g, rotation speed=500 rpm and pH=9.52. In this condition, the maximum adsorption capacity of synthesized LDH for cyanide was 73.80 mg/g. The equilibrium data and the kinetic data were best modeled by Langmuir isotherm model and pseudo-second-order kinetic model, respectively. The rate limiting step was determined to be intraparticle by adopting the adsorption data with Weber and Morris model and the adsorption of cyanide onto LDH is occurred through ion-exchange mechanism due to chemical composition and mineralogical structure of LDH. LDH synthesized using salts of industrial purity also showed high potential for removal of cyanide ions from the solution. Also, the treatment of a real wastewater by LDH showed that with an absorbent dose of 20 g /L, more than 84% of the cyanide can be removed from the wastewater.