محمود شمس الدینی نژاد

The porphyry copper deposit of Daralu is located 130 km south of Kerman province and in the metallogenicall zone of Dehaj-Sardouiyeh. The estimated Mineral storage of the deposit until 2019 is 294 million tons with an average grade of 0.35% Cu. The study of lithogeochemical zonality indicators is used to identify the type of deposit, determine the location and depth of the ore body. In this study, standard lithogeochemical zonality indicators that are used to identify the position of the world's porphyry copper deposits were compared with each other in the Daralu porphyry copper deposit. Among these indicators, the Cu/Mo zonality index and then the (Zn*Pb)/(Cu*Mo) show legal behavior Compared to other indicators, and their trend is steadily declining from surface to depth. Based on the numerical values of the zonality index (Zn*Pb)/(Cu*Mo) for the standard porphyry copper deposits, the ore body in Daralu deposit is located at an absolute height of 2950 to 2750 meters and the depth of the sub ore primary lithogeochemical haloes of the deposit were determined from 2750 to 2550 m. However, based on the numerical values of the Cu/Mo index, the final depth of the sub ore primary lithogeochemical haloes was estimated at 2425m, although the results of both indicators confirmed each other and overlapped. Also, by using the linear lithogeochemical productivity of the elements in different horizons, the lithogeochemical zonality sequence of the elements was calculated in the form of Mo-(V,Co)-Au-Ag-Ni-Pb-As-Sb-Cu-(Zn,Cd,Mn) from the depth to surface. The highest molybdenum value belonging to the absolute height of 2550 meters (the deepest part of the deposit) and the highest amount of lead were recorded at absolute height of 2950 meters (deposit surface). Indices and sequence of elements was determined that the supra ore is washed away and mineral mass is close to the surface.

Summary: In this research, the efficiency of electrical sounding method in recognizing the mineral layer in karstic bauxite deposits having coarse topography is investigated. For this purpose, 21 electrical sounding locations beside drilled points along a survey line in one of Jajarm bauxite deposit have been designed and surveyed. First, the acquired data have been interpreted using standard curves, and then, the obtained results have been modelled by IXID software. Because of enough resistivity contrast between the bauxite and dolomite bed rock, the recognition of basement is possible. Despite this, due to low resistivity contrast between the bauxite and upper layers, the recognition of upper layers, and thus, determination of the bauxite layer thickness is difficult. In order to investigate the accuracy of the results of the geoelectrical surveys in the mineralized area, these results were compared with the results of exploration drilling in the study area. After comparison, it was identified that estimation error of the results of 5 sounding locations were above 50%,, estimation error of the results of 10 sounding points were between 10% and 30%, and estimation error of the results of 6sounding locations was less than 10%. Kendall rank correlation coefficient between estimated depth of basement by geoelectrical method and the achieved depth of drilling results was 0.486 that revealed a good correlation between contact of recognized dolomite depth and bauxite from the interpretation of sounding results and from the results of drilling data in the study area.

Introduction: Bauxite exploration methods like exploration of most of minerals have divided into direct and indirect methods. Different drilling methods such as borehole drilling, core drilling and trench drilling are different kinds of direct methods, which are expensive and taking very much time. Among indirect exploration methods, we can refer to geophysical methods, which their applications are spreading because they are cheaper and faster, i.e. have higher operation speed. The major question of this research is whether electrical resistivity method is effective in bauxite exploration or not? and also, how much is the accuracy of modeling results and interpretation of electrical sounding surveys in determination of the depth and thickness of bauxite layer in the study area?

Methodology and Approaches: In this research, resistivity method has been used for recognition of bauxite layer in Jajarm bauxite mine. After preliminary studies and inspection of Jajarm bauxite mine, one part of that area has been selected as an area for planning and acquisition of geoelctrical surveys. This area has coarse topography that limits the planning of survey network. Finding the depth and thickness of the bauxite layer is the purpose of this research. As the resistivity in vertical direction changes more than resistivity in horizontal direction in the area, vertical changes in resistivity represent the properties of bauxite layer in the vertical direction, and thus, the Schlumberger electrode array was used for geoelectrical sounding surveys. The distance between successive sounding points in survey lines according to exploration boreholes was considered 25 meters. Geological and exploration reports as well as the positions of the bauxite outcrops show the dip of bauxite layers. Considering this point, 21 electrical sounding points having 25 m distances from each other were surveyed. In this research, first, electrical sounding data were interpreted by standard curves, and then, the achieved results as the primary model were modeled by IXID software. Kendall rank correlation coefficient between estimated depth of basement as a result of modeling electrical sounding data and the achieved depth of drilling results was 0.486 that revealed a good correlation between the basement depth from the interpretation of sounding results and from the results of drilling data in the study area.

Results and Conclusions: Five geoelectrical layers have generally been recognized in the study area as a result of the interpretation of all the acquired electrical sounding data, and also, the geological evidences from the area. Insufficient resistivity contrast between the bauxite unit and its overlying layer cause that these two units cannot be separable, and thus, determination of the thickness of the bauxite layer using geoelectrical method seems to be difficult. Although there is sufficient resistivity contrast between the bauxite unit and its underlying karstic dolomite basement, the estimated contact depths between these two layers from the interpretation of sounding data in 5 sounding locations, based on the drilling results in these locations, are not acceptable because of artificial noises from different human factors such as drilling equipment, drilling debris and other human installation, and also, because of geological noises such as varying thickness and dip of soil and rock layers and the existence of coarse topography in the study area. In general, based on the obtained results from the interpretation of the electrical sounding data, we can say that the accuracy of the geophysical method in estimation of subsurface information in this research is acceptable. We can also conclude that the geoelectrical method in the estimation of bauxite and basement layers has high accuracy.

Deralu Copper Mine in 120 Km of south of city Kerman and 35 Km of north Eastern Baft in mountain area, are rested between Hezar with high of 4465 meters and Lalehzar by high 4351 m mountains. Tailings dam for the processing plant, is a required facility for mining operation. Site selection of tailings dams has a great impact on the initial and final investment of the mining operations. The dam site selection process was based on economic issues and of ease of operation criteria in the past, but for now, due to the importance of the environmental issues, tailings dam site selection is a complicated process. In this study, determination of location of the copper mine tailings dam Deralu using GIS software as a decision support software is used. Many parameters affect the localization of tailings dam, which these parameters cause complexity in choice of localization of tailings dam. In this research, the Analytic Hierarchy Process (AHP) - based on weighting parameters by the experts, will attempt to locate - is used. The opinions of experts, consisting of five layers of geological, environmental, hydrological, and economic and morphology was classified. Then, paired comparisons were performed between the layers to weight. Simultaneously the weighted sets analyzes were inconsistent judgments. Finally, By field control operations, the four proposed areas for further research were identified. The four regions were compared using TOPSIS method and preferred option was chosen.