How to Select The Right Pyrite Beneficiation Method?

Do you want to get more pyrite from your ore? Are you looking for the best way to process your pyrite resources? Choosing the right beneficiation method can greatly improve your recovery rate and profits. In this post, I’ll share three common pyrite beneficiation methods. I’ll also explain how to choose the best one for your specific needs.

Pyrite is one of the most widely distributed sulfide ores in the earth’s crust and is the main mineral raw material for extracting sulfur and making sulfuric acid. Pyrite beneficiation aims to separate pyrite from other minerals in the ore. Usually, in the flotation of non-ferrous metal sulfide ores such as copper, lead, and zinc, pyrite is regarded as a by-product sulfur concentrate for recovery. If pyrite contains precious metal elements such as gold and nickel, it can also be recovered as the main product. At present, common pyrite beneficiation methods include gravity separation, flotation, and gravity-flotation combined methods. The best method depends on the specific properties of the pyrite ore, such as the ore grade, pyrite liberation size, and the presence of other minerals. Let’s dive into each method and explore their advantages and disadvantages. This will help you make an informed decision for your mining operation.

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• When to Choose Gravity Separation For Pyrite?
• When to Choose Flotation For Pyrite?
• When to Choose Gravity-Flotation Combined Method For Pyrite?
• Conclusion

When to Choose Gravity Separation For Pyrite?

Gravity separation is a simple and effective method for beneficiating pyrite ores. It works best when the pyrite is significantly denser than the other minerals in the ore. This difference in density allows us to separate the pyrite using gravity.

Gravity separation uses the density difference between pyrite and gangue minerals. Common gravity separation equipment includes jigs, shaking tables, and spirals. This method is cost-effective and environmentally friendly, making it suitable for coarse-grained pyrite ores.

There are several types of gravity separation equipment. Jigs use pulsating water to separate minerals based on density. Shaking tables use a combination of vibration and water flow. Spirals utilize centrifugal force to separate minerals as they flow down a curved path. Choosing the right equipment depends on factors like particle size and the degree of liberation. I once worked on a project where we initially used jigs but later switched to shaking tables for finer particles, resulting in a significant improvement in recovery.

When to Choose Flotation For Pyrite?

Flotation is a widely used method for separating pyrite from other sulfide minerals. This method uses the difference in surface properties of minerals. Certain chemicals are added to the ore pulp to make the pyrite hydrophobic (water-repellent) while the other minerals remain hydrophilic (water-attracting). Air bubbles are then introduced, and the hydrophobic pyrite particles attach to the bubbles and float to the surface, forming a froth layer that can be collected.

Flotation separates pyrite based on surface properties. Chemicals are used to make pyrite hydrophobic, allowing it to attach to air bubbles and float. This method is effective for fine-grained pyrite ores and complex sulfide ores.

In the process of pyrite flotation, short-chain pyrite is commonly used as a collector and sulfuric acid as an activator; the pH value of the flotation medium is an important factor affecting the effect of pyrite flotation. Short-chain pyrite is a traditional pyrite trap, and the hydrophobic product is double pyrite type. In an acidic medium, pyrite is easy to float at a pH of less than 6 due to the action of the yellow drug. As the pH increases, the floatability of pyrite decreases under alkaline conditions. Sulfuric acid is the activator of pyrite, which on the one hand can reduce the solution pH, so that Ca2+, Fe2+, Fe3+, and other ions on the surface of pyrite form complexes or insoluble salts, to restore the fresh surface of pyrite; on the other hand, due to its presence, the surface of pyrite is not easy to oxidize, to make the activation of inhibited pyrite to float. When the surface of pyrite is deeply oxidized, it can be activated by Cu2+. After Cu2+ replaces Fe2+, a copper-containing sulfide film is formed within the pyrite lattice, which improves the adsorption capacity of pyrrhotite.

Flotation is particularly effective for fine-grained ores where gravity separation is less efficient. The process involves several stages, including grinding, conditioning, and flotation. Careful control of parameters like pH, reagent dosage, and airflow is crucial for optimal performance. In my experience, regular monitoring and adjustments are essential to maintain a consistent and high recovery rate.

When to Choose Gravity-Flotation Combined Method For Pyrite?

Sometimes, a combination of gravity separation and flotation provides the best results. This approach is often used for ores with a wide range of particle sizes or complex mineralogy.

The combined method uses gravity separation for coarser particles and flotation for finer particles. This approach maximizes recovery and reduces overall processing costs. 

When pyrite contains vein minerals easy to mud, such as serpentine, chlorite, kaolinite, etc., the flotation process will produce a large number of slime cover on the surface of pyrite, inhibiting its floatability. Because of the above situation, the combined method of gravity separation-flotation can be used for pyrite beneficiation. The “gravity separation – flotation” process is better than the “single flotation” process indicators, with less consumption of chemicals, and flotation speed.

The combined method leverages the advantages of both gravity separation and flotation. The coarser, liberated pyrite is recovered using gravity separation, reducing the load on the flotation circuit. The finer particles, which are often more difficult to separate by gravity, are then processed using flotation. This approach maximizes overall recovery and minimizes reagent consumption in flotation. I remember a project where we implemented this combined method, and it resulted in a 15% increase in overall pyrite recovery compared to using only flotation.

The gravity separation-flotation method is also superior to the single-flotation method in the following aspects:

• Although the process is more complex, but because the grinding capacity is small, can choose a smaller ball mill classification system, so the investment in plant construction will be reduced.
• The spiral chute has removed a large amount of mud in the tailing process, there is no need to use specialized desliming equipment, and also improves the efficiency of the filtration equipment.
• It occupies a small area, has a large processing capacity, and has good environmental benefits.
• The grain size of the obtained product is coarse, which is favorable to the subsequent roasting process.

Conclusion

Choosing the right pyrite beneficiation method is crucial for maximizing recovery and profitability. Gravity separation is suitable for coarse-grained ores with significant density differences. Flotation is effective for fine-grained and complex sulfide ores. A combined approach can be the best solution for ores with a wide range of particle sizes or complex mineralogy. Remember, conducting thorough test work is essential to determine the optimal method for your specific ore.