عطاالله بهرامی

Considering the consumption of more than 25% of energy by raw mill materials in cement plants, providing a suitable plan for blending different mining zones can be an effective approach in reducing the energy consumption. The purpose of this paper is optimizing the plan of blending limestone mining zones to reduce milling energy consumption raw mills (ball mill and HPGR). The geomechanical properties of different mine zones have been identified by performing the bond work index, drop weight, and uniaxial compressive strength (UCS) tests. Also, to comply with cement production standards, cementing modules including S.I.M, A.L.M, and L.S.F have been calculated for different mine zones. Mining production planning with the aim of achieving the minimum comminution energy and transportation costs has been developed by the Goal programming method. Planning constraint equations are also considered to regulate cement modules. Finally, utilizing windows Quantitative System for Business software, the necessary calculations have been carried out. Based on the results, the extraction order and blending values of different mine zones are adjusted regarding cement modules and minimizing transportation costs, leading to a reduction in energy consumption of raw mills.

The reprocessing tailings of iron ore processing plants is important from economic (as a secondary source of iron) and environmental points of view. The aim of the present study is to determine the appropriate method for recovery iron from the tailings of Balestan iron ore processing plant (located in the northwest of Iran). For this purpose, after taking samples from the tail piles of this plant, a representative sample was selected, and chemical, mineralogical, size distribution, and bond’s work index analyses were performed on it. The total iron grade in the tailings was measured to be about 10%, of which 8.5% was identified as magnetite mineral (with a degree of liberation less than 40%). The d80 value of the sample was 7 mm, and the bond index was measured as 11.84 (kWh/ton). To determine the appropriate method for iron recovery, pre-processing with magnetic drum, grinding, and Davis tube tests were performed. With the magnetic pre-processing of tailings with a particle size of 0-10 mm, under a field of 2000 G and in a dry method, about 80% of the load entering the drum with a total iron grade of 5% was transferred to the tailings. 20% of the input load with an iron grade of approximately 24% was recovered to the concentrate. In order to remove the gangue minerals and enrich the pre-processed concentrate, stepwise grinding and separation had the best results. Comminution was done in two stages to produce products with smaller dimensions of 250 and 45 microns, respectively. Magnetic separation was also done in three stages with 3000 G, and two stages of separation with 1000 G, which finally resulted in a concentrate with a total iron grade of more than 66% and iron recovery of 44.88%.

Dewatering and water recycling operations in mineral concentration processes lead to not only cost-effective water use, but also less waste disposal to the environment. In this study, optimization of dewatering process in Zareshouran gold processing plant is carried out using hydrocyclone containing circuit. For this purpose, 12 experiments using 4 spigots with 2, 3, 6, 9 mm diameter, and in 3 operation state of spray discharge, transition state and rope discharge have been conducted. Dewatering capability of hydrocyclone is evaluated based on solid weight percent and solid recovery of underflow stream. The results indicate that in the same operation state, increase in spigot diameter leads to an increase in solid recovery and a decrease in solid weight percent of underflow stream. On the other hand, as the operation state tends to rope discharge solid weight percent and solid recovery of underflow increases simultaneously. Therefore, it can be stated that spray discharge pattern has a higher dewatering capability. Using a spigot with 6mm diameter in the operation state of spray discharge, solid recovery and solid weight percent reaches 75 and 61%, respectively. In this condition, if hydrocyclone is considered as the first step of dewatering process, 75% of the feed solid content can be directly transferred to tailings dam at a lower cost. On the other hand, the overflow stream carries only 25% of feed solid content. If pressure filter present in current dewatering system are considered as the second step of dewatering process, their feed slurry will be reduced by 75%. This means an overall increase in dewatering system capacity by hydrocyclone.

Mines and mining industries are an important way to reach the sustainable development and investing in these sectors creates the suitable economics value added. Therefore, prioritization of the mineral activities are helpful for persuasion of future investments. The main aim of this research is to rank the mining activities of the Azerbaijan-e-Gharbi Province in Iran with considering five main criteria including economic, cultural and social, environmental, technical and also political criteria.

In this study, the main in-operation mines are considered. The technique for order of preference by similarity to ideal solution and also the analytical hierarchy process are used to prioritize the mining activities. To reduce the uncertainties, all calculations are done under the fuzzy environment. Results and

Results of this study show that, the cultural, social and environmental criteria have the highest importance degree in comparison to the other criteria. The iron and gold mines are in the first priority, while the chromic and manganese mines and lead and zinc mines are respectively in the second and third priority. The quarry and gypsum mineral types, the barite, red and yellow soil, kaolin, fireclay and dolomite, salt and silica, sand, rubble, mica, limestone and ballast mines are respectively ranked.

Contamination caused by tailing dams of mineral processing plants is one of the most important problems facing the mineral industry and that causes many environmental problems. Among these, we can point out to the contamination caused by the tailing dams of gold processing plants. This wastewater contains significant amounts of cyanide and its compounds. So far, various biological and chemical methods have been investigated for eliminating cyanide in gold processing waste. One of the methods used by researchers is the use of natural absorbents such as activated charcoal, due to the ease of use and the its reusability. In this research, the adsorption of cyanide of the tailing dam wastewater of the Zarshuran gold processing plant (35 km from Takab, West Azarbaijan Province) using Shahin Dezh coal mine (about 100 km from the plant) was investigated. Cyanide adsorption experiments were performed on a laboratory scale under two modes of using crude charcoal and processed charcoal. First, the charcoal sample was poured into the cylinder up to the height of 75 mm. In the next step, the effluent containing cyanide was added to the cylinder (up to 100 mm) and the cyanide output flow rate was measured. After the experiments, charcoal samples were dried in open air, and ash percentage analysis was performed for each of them. The resultant solution of each test was filtered with Whatman paper No. 75 and analyzed for cyanide content. According to the results of the experiments, the granulation fraction of -2±1 mm had the highest output flow rate of 8.16 mL.min-1 and the lowest flow rate was related to particles less than 1 mm in size. The highest output flow rate for processed charcoal was obtained at 10.61 mL.min-1 in the granulation fraction of -2±1 mm. Based on analysis of the amount of ash, after the cyanide adsorption operation, the amount of ash in fractions of –4.75 and +4.75 ± 2 mm decreased by 0.7 and 3.7%, but, after cyanidation, the amount of fractions + 1 mm increased by 11.8%. In all experiments, cyanide adsorption using crude charcoal has the highest absorbance value for grain size in the range of -2±1 mm. The amount of cyanide adsorbed in this fraction for crude coal, processed coal and coal mixed with cyanide using a mechanical stirrer is 42.3, 31.78 and 21.88%, respectively. In this study, isotherm adsorption models of cyanide on charcoal were also studied based on Langmuir and Freundlich. The absorption process in all granulation fractions matched most closely the Freundlich model, indicating that that adsorption of cyanide follows a multi-layer adsorption onto the heterogeneous surface of the charcoal. The adsorption phenomenon occurs in different absorbent intake regions as a result of various forces, both physical and chemical. The results of this study indicate that processing the charcoal does not have any effect on the absorption of cyanide, and physical properties such as particle size and the specific surface area of coal are the most important factors in the absorption of cyanide. The results of this study indicate that the use of coal from the Gozlu mine Shahin Dezh, located a few kilometers from the tailing dam, with a grain size of -2±1 mm, in the form of crude in the bed and bottom of the dam, can significantly reduce the cyanide contamination of underground water resources.