Application of Pneumatic Flotation Columns in Copper Mining

Copper is one of the earliest metals discovered and used by humans. It is a metal with a purplish-red luster, slightly hard, extremely tough, wear-resistant, with good ductility, thermal conductivity, electrical conductivity, and corrosion resistance. Copper and its alloys are stable in dry air, but in moist air, a greenish layer of basic copper carbonate (Cu₂(OH)₂CO₃), commonly known as copper patina, forms on its surface. Copper in nature is classified into native copper, copper oxide ore, and copper sulfide ore. Common compounds include cupric hydroxide, cupric oxide, and cupric sulfate. Due to its abundant reserves, excellent properties, and convenient processing, copper is widely used in fields such as electrical, mechanical manufacturing, construction, and transportation, ranking second only to aluminum in the consumption of non-ferrous metal materials inChina.

Flotation columns are mainly used in the scavenging stage of copper ore flotation recovery, usually replacing the 2-3 stages of flotation machines with a single-stage flotation column. From successful mining case studies around the world, it is generally observed that after replacing the flotation machines with flotation columns, the concentrate grade and recovery rate are improved to varying degrees. Below are some typical application cases to illustrate the application of flotation columns in copper mining.

1.      Dashan Concentrator of Jiangxi Dexing Copper Mine

The original design of Dashan Concentrator used a mixed and separated flotation process. In order to further improve the concentrate grade of copper, experimental research on new reagents and new process for improving the concentrate grade of copper was carried out in Dashan Concentrator from 2000 to 2001, and the original mixed and separated flotation process was changed to a priority mixed and step-by-step flotation process.

After using the priority mixed and step-by-step flotation process, the problem of insufficient flotation time due to inadequate equipment became prominent. The yield of priority flotation concentrate was about 4%, and 15 flotation machines were used for two-stage flotation, resulting in severe shortage of flotation time. Although the grade of the first-stage copper concentrate could reach 27.5%, the recovery rate was only 80%, increasing the pressure of mixed flotation. Due to the low grade (about 1.5%) and fine particle size (75%~80% of -38μm grade) of the mixed flotation concentrate, the grade of the final concentrate after two-stage flotation was only about 18%.

Because the particles of copper in the mixed flotation stage are fine, the upward speed in the flotation machine is slow, resulting in increased flotation times and low recovery rate. To solve this problem, inflatable flotation columns were used to replace the priority mixed flotation in the scavenging stage. The production results after the transformation are shown in the table below:

From the production indicators, it can be seen that the use of flotation columns instead of the original flotation machines for scavenging operations effectively improves the flotation speed, and the recovery effect on fine particles is better, resulting in varying degrees of improvement in concentrate grade and recovery rate, and good economic benefits were achieved.

Through energy consumption statistics, it was found that after using flotation columns instead of flotation machines for scavenging operations, energy savings of 39% were achieved, saving about 1200 kW per hour.

2.      Xianglin Copper Concentrate Column Flotation Modification in Jiangxi

The original flotation process involved three stages of concentration, with the grade of the concentrate fluctuating frequently and being unstable. By replacing the original three-stage concentration process with a column flotation for one-stage concentration, the flotation process becomes more stable, and both the grade of the concentrate and the recovery rate are improved. Additionally, energy consumption is reduced by around 30%, resulting in significant economic benefits. The production results are shown in the table below:

3.      Copper Slag Flotation Recovery at Daye Nonferrous in Huangshi

The copper slag beneficiation plant of Daye Nonferrous in Huangshi collects copper from the copper slag produced during the smelting process. Due to the high density of the ore, coarse particle flotation machines were used for flotation, but it was difficult to further improve the recovery rate after reaching 63%. Through tailings analysis, it was found that the lost copper minerals were mainly distributed in fine particles. Due to limitations in the plant layout, it was decided to add a column flotation directly outside the plant in order to increase the recovery rate of fine particle copper.

The original flotation process was as follows: two-stage continuous grinding (fineness -200 mesh, 85-90%); one roughing, one cleaning, and three scavenging; rough concentrate concentration of 45%. Technical indicators were as follows: original ore grade: 0.8%; concentrate grade: 16%; tailings grade: 0.3%; recovery rate: 63.69%.

The modified flotation process with the addition of the column flotation is as follows: two-stage continuous grinding (fineness -200 mesh, 85-90%); one roughing, two cleaning, and three scavenging; rough concentrate concentration of 45%, with the column flotation used in the final scavenging. Technical indicators were as follows: original ore grade: 0.8%; concentrate grade: 16%; tailings grade: 0.25%; recovery rate: 69.84%. After the modification, under the same conditions of copper concentrate grade, the copper recovery rate increased by 6.15 percentage points.

In conclusion, when column flotation is used for fine particle mineral flotation, it can capture finer mineral particles than flotation machines, resulting in better flotation performance.

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