Phosphate ore beneficiation methods

Phosphate ore beneficiation methods are diverse, with the globally prevalent techniques currently including flotation, scrubbing and desliming processes, gravity separation, and calcination-digestion processes. With technological advancements, electrostatic separation, bioleaching, chemical beneficiation, and combined applications of multiple processes are also becoming increasingly widespread.

Flotation remains the dominant method due to its excellent separation efficiency and broad applicability. This process exploits differences in mineral surface properties, using reagents to selectively adsorb target minerals onto froth for separation. It can be categorized into positive flotation and reverse flotation.

The scrubbing and desliming process is a purely physical beneficiation method, primarily suited for weathered or high-clay-content phosphate ores. It features simple operation, suitability for open-pit mining, chemical-free processing, and environmental friendliness. The core process involves removing clay and fine silt from mineral surfaces through hydraulic scrubbing, followed by screening to obtain high-quality phosphate concentrate.

Another common method is gravity separation, also known as gravity beneficiation. It utilizes density differences between minerals to achieve stratification or separation in water, air, or heavy media. This method features a simple process flow, low cost, and no pollution, making it frequently used for pre-sorting gangue and phosphate minerals with significant density variations.

The calcination-digestion process falls under chemical beneficiation. It decomposes carbonates in phosphate ore into oxides and releases carbon dioxide through high-temperature calcination, simultaneously removing organic matter to enhance phosphorus grade. Subsequent leaching with water or acid further removes impurities, achieving ore purification.

Chemical leaching processes also rely on chemical reactions to dissolve and separate impurities from phosphate ore. Compared to traditional physical methods, they can process a wider range of ore types, particularly those with complex compositions that are difficult to separate physically.

Within physical separation, methods exist based on differences in mineral optical, electrical, and magnetic properties. For instance, optical sorting utilizes variations in light absorption, reflection, and transmission characteristics; electrostatic separation exploits conductivity differences between phosphate minerals and gangue, separating them through force and trajectory differences in an electric field. As a dry process, it features no wastewater, minimal pollution, simple equipment, and low operating costs.

Biological leaching represents a more environmentally friendly technological direction. It leverages the metabolic activity of specific microorganisms to decompose harmful components within ore under suitable conditions, converting insoluble phosphorus into soluble forms and thereby enhancing resource availability.

Additionally, technological advancements continue to yield new separation methods such as gas-solid separation, magnetic hooding, electron beam sorting, and selective flocculation. In practice, combining multiple mineral processing techniques often leverages their respective strengths, improving overall separation efficiency and resource utilization. Nevertheless, flotation remains the most widely applied process globally for phosphate ore beneficiation due to its comprehensive advantages.