The depletion of sulfide zinc ore reserves and the environmental challenges associated with pyrometallurgical processing have necessitated the development of viable hydrometallurgical techniques for zinc extraction from low-grade oxide ores. This research delves into the feasibility of zinc recovery from the low-grade oxide ore of Mehdi Abad mine, Yazd, Iran, employing both tank leaching and heap leaching methods.Sampling was conducted from the low-grade oxide section of Mehdi Abad mine. Following sample preparation, XRD and XRF analyses were performed to characterize the ore's mineralogical and elemental composition. To enhance the ore grade, high-intensity magnetic separation, gravity separation, and magnetic roasting methods were investigated. Bottle roll tests were employed to determine acid consumption, while column leaching experiments were conducted to eva‎luate the efficacy of heap leaching. In tank leaching, the effects of pH, temperature, pulp density, and particle size were examined to establish optimal operating conditions. XRD analysis revealed barite, hematite, quartz, and goethite as the primary mineral phases, with chlorite and hemimorphite as secondary phases. The zinc and lead grades were determined to be 4.46 ppm and 3.81 ppm, respectively. In order to increase the grade of zinc oxide ore, the methods of high intensity magnetic grading, gravity separation and magnetite reduction purification were investigated. Magnetic roasting demonstrated superior performance compared to high-intensity magnetic separation and gravity separation, But respectively The results showed that pre-concentration methods are not effective in increasing zinc recovery, in the magnetic product.Acid consumption was quantified at 179.3 kg/t ore. Heap leaching experiments indicated zinc recoveries of 26.21% for 20 mm particles after 83 days and 31.07% for 10 mm particles after 69 days of operation. In tank leaching, the highest zinc recovery (61.21%) was attained under conditions of pH 0.5, 20% pulp density, 450 rpm agitation speed, 75 µm particle size, and ambient temperature with a residence time of 3 hours. Increasing the pH to 1.5 to minimize acid consumption resulted in a decreased recovery of 56.23%. The presence of chalcophenite mineral in the ore necessitates the use of sodium sulfite as a reducing agent to increase zinc recovery. The leaching test was performed with sodium sulfite in 280ml of water, pH = 1.5, solid percentage 20%, stirring speed 450 rpm, particle size 75 microns and temperature 60 degrees Celsius with a retention time of 3 hours and the results showed that the recovery of zinc was 70. 03% increased, which shows the positive effect of the regeneration agent. Based on the findings of this research, the mixing leaching method with sodium sulfite reducing agent is more efficient than the column leaching method for extracting zinc from Mahdi Abad oxide ore. Therefore, the mixing leaching method is suggested for this purpose.

علي احمدي عامله

ابراهيم عظيمي , كيومرث زرگوش