Copper-Nickel Sulfide Ore Flotation Process

In copper-nickel sulfide ores, copper exists in the form of chalcopyrite. Nickel exists in the form of free nickel sulfide, such as pentlandite, pentlandite, and purple sulfur nickelite. A considerable part of nickel exists in pyrrhotite in the form of isomorphism. There are many beneficiation methods for this type of nickel ore, such as flotation, magnetic separation, gravity separation, etc., but flotation is the main separation method.

1. priority flotation process

The process is mainly for ores with high copper content and low nickel content and simple properties. The priority flotation process of copper-nickel sulfide ore usually adopts the process of "floating copper and suppressing nickel". The separation of copper and nickel is achieved by adding inhibitors of nickel sulfide minerals and high-efficiency collectors of copper. It is suitable for processing copper-nickel minerals with higher copper content than nickel, and the copper concentrate is preferentially flotation.

• Advantages: Copper concentrate with low nickel content and qualified nickel concentrate can be obtained directly, and the cost is low.
• Disadvantages: The suppressed pentlandite and purple sulfur nickel ore during copper flotation are difficult to activate in subsequent flotation, resulting in low nickel recovery rate and waste of nickel resources.

2. Mixed flotation of copper-nickel sulfide ore

Mixed flotation of copper-nickel sulfide ores is mostly suitable for sorting copper-nickel ores with lower copper than nickel content. The process method is to extract copper and nickel minerals by mixing and flotation from the ore, and then separately select copper concentrate (containing low nickel) ore and nickel (containing low copper) concentrate from the mixed concentrate. The obtained nickel concentrate can be directly smelted.

(1). Copper-nickel mixed flotation re-separation process
Copper-nickel mixed flotation-the flotation process of mixed concentrate to suppress nickel and float copper is the most commonly used copper-nickel beneficiation process in copper-nickel sulfide ore beneficiation plants. The process is to first obtain copper-nickel mixed concentrate through copper-nickel mixed flotation. After the mixed concentrate is grinded to remove chemicals, the method of suppressing nickel and floating copper is used to separate copper concentrate and nickel concentrate.

(2). High nickel matte regrinding flotation separation process
The high-nickel matte regrinding flotation separation process refers to first adopting copper-nickel mixed flotation to obtain copper-nickel mixed concentrate, then mixing the concentrate to form low-nickel matte through electric furnace smelting. Then it is transformed into artificial high-nickel matte ore through converter blowing, and finally, the high-nickel matte ore is re-grinded and flotation-separated.

This process is mainly aimed at the ore whose copper-nickel associated relationship is complex and the particle size is extremely fine. The direct flotation copper-nickel separation method cannot complete the copper-nickel separation. High-nickel matte is mainly composed of Ni3S2, Cu2S, copper-nickel-iron alloy and a small number of platinum group elements. The iron content, sulfur content and copper-nickel ratio of high-nickel matte are important factors affecting the subsequent flotation separation process.

• Advantages: Compared with the layered smelting method, electrolysis method and leaching method, the flotation separation process of high-nickel matte has the advantages of short process and low energy consumption.
• Disadvantages: The flotation separation of high nickel matte usually suppresses nickel and floats copper under high alkali conditions. When the pH value of the slurry is too high, it will also have a certain inhibitory effect on Cu2S, and it is during the preparation of high nickel matte. Ni3S2 and Cu2S wrap each other, and xanthate is mostly used as collector. The selectivity to the two minerals is poor, and the inner containment of copper and nickel in the obtained concentrate is still not ideal.

3. Electrochemical control flotation process of copper-nickel sulfide ore

(1) Electrochemical control flotation is to change the electrochemical characteristics of flotation pulp by chemical agent control, adjust the buoyancy of minerals, and realize the flotation separation of minerals. In the flotation of copper-nickel sulfide ore, the potential regulation methods are as follows:
i. Controlling the oxidation process on the surface of copper-nickel sulfide minerals during grinding and flotation by oxidizing agents;
ii. By adjusting the pH value of the pulp, controlling the electrochemical characteristics of the copper-nickel sulfide mineral surface, and providing a reasonable flotation pulp environment;
iii Add chemicals to prevent excessive oxidation of copper-nickel sulfide minerals during flotation.

(2) Potential-regulated flotation can be divided into two types from the means of realization: chemical agent regulation and external electrode regulation. These two control methods are relatively mature, but each has its own advantages and disadvantages.
i. Chemical agent control method
This method does not require major modification of the original flotation equipment, and the control effect is better. However, a large amount of oxygen will enter the slurry system during aerated flotation, making it difficult to maintain the slurry potential within an appropriate range. Increased the amount of redox agent, which is unfavorable to the subsequent flotation.

ii. External electrode control method
The method has the advantages of simple and fast operation, and will not increase the unavoidable ions in the pulp. However, the original flotation machine must be modified and electrodes must be installed, resulting in higher installation and maintenance costs.