Tin and copper are metals that were discovered and used early in human history, and they have close relationships with human activities. They are widely used in electronics, chemical industry, construction materials, aerospace, and other fields. With the development of mining history and scale, easily accessible tin and copper ore resources have become scarce. The tin and copper ore resources available for exploitation are becoming more complex. Therefore, comprehensive recycling and utilization technologies are increasingly emphasized.
In production practice, commonly used beneficiation methods for tin ore and copper ore are regrinding and floatation. Due to the complex composition of most tin-copper ores in nature, with various valuable components, effective comprehensive recovery of tin, copper, and other valuable components often requires the combined use of physical or chemical beneficiation methods such as regrinding, magnetic separation, electrostatic separation, floatation, leaching, and roasting.
In a certain tin-copper ore, tin and copper exist in the forms of cassiterite and copper sulfide, respectively. A regrinding-floatation combined process was tested for the recovery of tin and copper from the ore.
The main valuable elements tin and copper in the ore have concentrations of 0.59% and 0.18%, respectively, while the harmful impurity arsenic has a concentration of 1.86%. Tin is mainly present in the form of cassiterite, and copper is mainly present in the form of copper sulfide.
Due to the significant density difference between the economically valuable mineral cassiterite and other minerals in the ore, and the easy pulverization of cassiterite during the grinding process, an economically and environmentally friendly regrinding method was first used to recover cassiterite from the ore. Then, floatation was employed to recover copper from the sulfide copper minerals.
(1) Spiral chute regrinding
When the feed particle size to the spiral chute regrinding was -0.9 mm, a tin concentrate with a tin grade of 1.23% and a tin recovery of 89.21% was obtained, achieving the preliminary enrichment of tin minerals. Therefore, the feed particle size to the spiral chute regrinding was determined to be -0.9 mm.
(2) Spiral chute concentrate shaking table classification
The shaking table was used to further enrich the spiral chute concentrate, resulting in a tin concentrate with a tin grade of 24.47% and an overall recovery rate of 81.99%.
(3) Shaking table reprocessed tin concentrate floatation desulfurization and arsenic removal
Analysis of the shaking table reprocessed tin concentrate showed high sulfur and arsenic content. To obtain qualified tin concentrate, floatation desulfurization and arsenic removal experiments were conducted on the shaking table reprocessed tin concentrate.
Through floatation desulfurization and arsenic removal, the sulfur and arsenic content of the tin concentrate decreased from 2.98% and 16.79% to 0.28% and 0.41%, respectively. The tin grade of the tin concentrate increased from 24.10% to 54.29%, with a tin recovery rate as high as 99.02%.
(1) Lime dosage test
Increasing the lime dosage from 1,000 g/t to 2,000 g/t resulted in a significant decrease in arsenic content in the copper rough concentrate from 3.35% to 1.61%. The copper grade increased from 1.11% to 1.68%, and the copper recovery rate decreased slightly from 63.67% to 61.38%. The arsenic recovery rate decreased significantly from 31.06% to 9.22%. Continuing to increase the lime dosage led to a substantial decrease in the copper recovery rate. Therefore, the lime dosage for copper roughing was determined to be 2,000 g/t.
(2) BK302 dosage test
With the increase in BK302 dosage, the copper grade of the copper rough concentrate decreased, and the copper recovery rate increased, while the arsenic index did not change significantly. Considering all factors, the BK302 dosage for copper roughing was determined to be 20 g/t.
(3) Copper floatation closed-circuit test
Through copper ore closed-circuit floatation, a copper concentrate with a copper grade of 23.05% and a copper recovery rate of 53.74% was obtained.
After the above floatation process, a tin concentrate with a tin grade of 53.97% and a tin recovery rate of 80.10%, as well as a copper concentrate with a copper grade of 22.67% and a copper recovery rate of 54.07%, were obtained.
With ore grinding to a particle size of -0.9 mm, the tin concentrate was pre-enriched using a spiral chute to separate high-density cassiterite. After rough removal (+0.5 mm rod mill) and shaking table classification and separation of the pre-enriched concentrate, reverse floatation was used for arsenic desulfurization to obtain a high-quality tin concentrate.
Then, floatation was employed to recover copper from the tailings of tin selection. After grinding the copper rough concentrate to -0.043 mm, accounting for 85% of the cases, a copper concentrate was obtained through three stages of floatation. The first stage of roughing concentrate, two stages of scavenging concentrate, and other middlings were returned in sequence. Finally, a tin concentrate with a tin grade of 53.97% and a tin recovery rate of 80.10%, as well as a copper concentrate with a copper grade of 22.67% and a copper recovery rate of 54.07%, were obtained.
