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Click to add WeChatThe main useful component of phosphate ore is apatite, and the content of phosphorus (P) is a key indicator for measuring the quality of phosphate ore. Apatite has a complex crystal structure and belongs to the hexagonal crystal system. Its crystals are often hexagonal columns or plates. Most phosphate ores in nature have low grades and often coexist with other gangue minerals. These are the main factors affecting the quality of phosphate ores and subsequent processing performance. At present, flotation is one of the commonly used methods in phosphate ore dressing and purification, which can effectively increase the grade of phosphate ore from 10%-15% to more than 30%. In the flotation process, the use and selection of reagents are the key to improving flotation efficiency. This article mainly introduces what reagents are commonly used in phosphate ore flotation?
Fatty acid collectors (such as oleic acid, linoleic acid, etc.) will dissociate in the slurry, and their anion part can react chemically with calcium ions (Ca²⁺) on the surface of apatite to form chemical bonds or chemical adsorption, making the apatite surface hydrophobic.
This type of collector has a good collection ability for apatite, is widely available, and is relatively cheap. However, its selectivity is relatively poor and is easily affected by other ions in the slurry (such as Ca²⁺, Mg²⁺, etc.). When there are a large number of calcium and magnesium ions in the slurry, they may react with the collector to form precipitation or consume the collector, reducing the selectivity and collection effect of the collector on apatite.
Phosphonic acid collectors (such as styrenephosphonic acid, alkylphosphonic acid, etc.) contain phosphonic acid groups (-PO (OH)₂) in their molecules, which can strongly chemically adsorb with calcium ions on the surface of apatite to form stable chemical bonds. This chemical bonding action converts the hydrophilicity of the apatite surface into hydrophobicity, thereby achieving separation from gangue minerals.
Phosphonic acid collectors have high selectivity for apatite and strong collection ability. They can work effectively in a wide pH range and can achieve better flotation effects at lower reagent dosages, reducing reagent costs. However, the synthesis process of phosphonic acid collectors is relatively complex and the cost is high, which limits its large-scale application to a certain extent.
Pine oil, also known as 2# oil, is mainly composed of terpene alcohol, which can reduce the surface tension of water and form stable bubbles in the slurry. When the slurry is stirred and aerated, the bubbles generated by pine oil can carry the apatite particles that have been hydrophobic due to the collector to float to the surface of the slurry to form a foam layer, thereby separating apatite from gangue minerals. Its action process is to make the bubble surface have a certain elasticity and stability through adsorption at the gas-liquid interface, preventing the bubble from bursting prematurely.
Pine oil has the characteristics of strong foaming ability and moderate foam stability. It can adapt to various phosphate ore flotation process conditions and is widely used in different types of phosphate ore flotation. Its price is relatively reasonable and its source is stable. However, it is necessary to control its dosage during use.
Water glass is sodium silicate. It mainly plays the role of inhibiting gangue minerals in phosphate ore flotation. It will hydrolyze in the slurry to form silicate colloid. The silicate colloid can be adsorbed on the surface of gangue minerals to form a hydrophilic protective film, which prevents the adsorption of collectors on the surface of gangue minerals, thereby keeping the gangue minerals hydrophilic and not floating with bubbles.
Water glass is a commonly used inhibitor with the advantages of good inhibitory effect, low price and wide source. It can inhibit a variety of gangue minerals, such as quartz, feldspar, mica, etc., and is widely used in phosphate flotation. However, the inhibitory effect of water glass has a certain selectivity. If the dosage is not properly controlled, it may also have a certain inhibitory effect on apatite, affecting the flotation recovery rate of phosphate ore.
Sodium hexametaphosphate can react with multivalent metal ions in the pulp to form stable complexes. These complexes can eliminate the adverse effects of metal ions on flotation, because metal ions may react with collectors to form precipitation, reduce the effectiveness of collectors, or adsorb on the surface of minerals to change the surface properties of minerals and affect flotation selectivity.
Sodium hexametaphosphate has a strong complexing ability for metal ions, which can effectively improve the flotation environment and improve flotation selectivity. It has a significant effect in inhibiting calcium and magnesium gangue minerals and eliminating the interference of metal ions on flotation reagents. However, the cost of sodium hexametaphosphate is relatively high, and the cost and effect need to be considered comprehensively when using it.
pH regulators (such as sodium carbonate, sulfuric acid, etc.) are used to adjust the pH value of the pulp in phosphate ore flotation to create a suitable flotation environment. Different flotation reagents have different activities and selectivities at different pH values. When using fatty acid collectors, it is usually necessary to adjust the pulp pH value to between 8 and 10. In this alkaline environment, fatty acid collectors can fully dissociate and play a better collection role; when using amine collectors, it may be necessary to adjust the pulp pH value to the acidic range so that the amine collector exists in the form of cations to enhance the capture ability of apatite.
By accurately controlling the pH value of the slurry, the performance of the flotation reagent can be optimized and the separation effect of apatite and gangue minerals can be improved. Sodium carbonate, as an alkaline regulator, has the advantages of good buffering performance and low corrosion to equipment; sulfuric acid, as an acidic regulator, can adjust the pH value quickly, but it is necessary to pay attention to safety when using it to prevent it from causing damage to equipment and operators.
In summary, phosphate ore flotation reagents play a key role in the phosphate ore beneficiation process. By reasonably selecting and using reagents such as collectors, frothers, inhibitors and regulators, it is possible to effectively separate apatite from gangue minerals, improve the grade of phosphate ore, and meet the needs of agriculture and chemical industries for high-grade phosphate ore. In practical applications, it is necessary to optimize the reagent system according to factors such as the specific properties of phosphate ore, flotation process requirements and economic and technical conditions to achieve ideal flotation effects.
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