Jarosite precipitation process (JPP) is the most frequently used procedure for iron removal in the hydrometallurgical zinc extraction process. However, there is a gap in the knowledge of the relationship between operational parameters and the low contaminant JPP on the industrial scale. This study will address these issues by investigating the behavior of zinc calcine (ZC) as a neutralizing agent, exploring the source of zinc and iron through leaching experiments, and simulating the Jarosite process of the Bafgh Zinc Smelting Company (BZSC). The results showed that the zinc dissolution efficiency was 90.3% at 90 °C, and 73% of the iron present in the calcine can be solubilized. The main outcome was the iron removal of about 85% by alkaline ions present in ZC without the addition of any precipitating agent. The second target was to evaluate the effect of operational parameters on jarosite precipitation. Results revealed that increasing the temperature to 90 °C and the stirring rate to 500 RPM as well as adjusting the ZC’s pH during the jarosite precipitation remarkably improved iron removal. Considering all these factors in the plant could improve Fe precipitation to around 80% on average.

Bubble loading is the ratio of the weight of the solid particles to the bubble’s surface, and it has an effective role in the flotation efficiency. This paper investigates bubble loading an industrial processing circuit through considering the important role of the bubble diameter in calculating bubble loading, and the effect of the aeration rate and frother dosage on the bubble diameter. The ratio of the weight of solid particles to the bubble volume was estimated to be in the range of 8 to 24 g/L. Although increasing the aeration could result in increasing the weight of the particles attached to the bubbles, the bubble loading was reduced by increasing the aeration rate due to its impact on the bubble diameter and the percentage of bubble surface coverage. For example, when the aeration rate was increased from 45 to 146 m³/h, the bubble loading decreased from 23 to 12 g/L. By increasing the frother dosage from 70 to 150 mL/min, the bubble loading increased from 16 to 19 g/L.

The effects of flotation operation parameters, including froth depth, air flowrate, and frother dosage, on the froth and collection zone recovery and the flowrate of particles into the froth phase were investigated in a 10 m³ industrial cell. The results showed that froth recovery increases upon increasing air flowrate and frother dosage, as well as reducing froth depth. While all tested parameters affected the particles that entered into the froth phase, air flowrate and frother dosage showed the most and least significance, respectively. When the air flowrate, frother dosage, and froth depth were 146 m³/h, 150 mL/min, and 5 cm, respectively, froth recovery was found to be above 84%. Also, the effect of the parameters studied on collection zone recovery was different from their effect on the froth zone, with air flowrate having the greatest impact on the former.

Iron ore beneficiation is crucial for sustainable utilization of low-grade iron ores. Conventional separation methods often fail to efficiently upgrade the iron ores containing complex mineral phases, such as hematite, goethite, ankerite, and limonite. This study evaluated an integrated roasting–leaching–magnetic separation approach applied to an iron ore. Roasting at 800 °C for 90 min significantly enhanced the Fe(II) content and improved magnetic susceptibility, facilitating superior iron-containing minerals separation efficiency. Furthermore, sulfuric acid leaching effectively eliminated non-magnetic impurities such as calcite, improving iron recovery. Davis tube recovery experiments confirmed that this combination markedly enhanced weight recovery (R_w) and iron recovery (R_g), outperforming traditional methods. The findings highlight the synergistic effect of roasting and leaching for refining iron ores and propose an optimized beneficiation strategy. This approach offers an effective method for processing complex iron ores, particularly those with low Fe grade and challenging impurities, improving beneficiation efficiency and mineral extraction.