Rare earth ore flotation and flotation equipment

Rare earth ore is an indispensable key raw material for modern industry, and its separation process is crucial. Flotation plays an important role in the field of rare earth ore beneficiation. It cleverly utilizes the difference in physical and chemical properties between the surface of rare earth minerals and gangue minerals. By adding specific flotation agents, rare earth minerals are selectively attached to bubbles and float up, thereby separating from gangue minerals. In-depth exploration of rare earth ore flotation technology and supporting flotation equipment is of far-reaching significance for improving the efficiency of rare earth ore beneficiation and ensuring the high-quality supply of rare earth resources. Let's learn about rare earth ore flotation from the principle characteristics and equipment.

1. Flotation principle of rare earth ore

Rare earth minerals and associated gangue minerals differ in crystal structure, chemical bond type, surface functional groups, etc., which leads to completely different surface wettability. Generally speaking, the surface of rare earth minerals is relatively hydrophobic, while the surface of gangue minerals such as quartz and calcite is hydrophilic. In the flotation system, after adding the collector, one end of the collector molecule can selectively adsorb on the surface of the rare earth mineral, change its surface properties through chemical adsorption or physical adsorption, and enhance its surface hydrophobicity; the other end extends to the water phase, creating conditions for subsequent bubble attachment.

The formation of bubbles is to supply air through an external blower to form tiny bubbles. Since the surface of the rare earth mineral is hydrophobic after the action of the collector, it is easy to attach to the bubbles, and the bubbles float to the surface of the slurry to form a foam layer. The hydrophilic gangue minerals are difficult to attach to bubbles and remain in the slurry, realizing the separation of rare earth minerals and gangue minerals at the gas-liquid-solid three-phase interface. This separation process based on surface properties and bubble action can accurately enrich rare earth minerals from complex ore systems.

2. Characteristics and application scope of rare earth ore flotation

Compared with some mineral processing methods such as gravity separation, flotation can be separated based on the subtle chemical property differences on the surface of minerals. For ores with complex mineral composition and rare earth minerals with fine particle size, it can effectively remove gangue minerals and obtain high-grade rare earth concentrates. In addition, it can process rare earth ores of different types and properties, whether they are primary ores, secondary ores, or various complex paragenetic ores. As long as the appropriate flotation reagent system and process conditions are found, it is expected to achieve efficient separation. At the same time, the flotation process can be flexibly combined with other beneficiation methods such as gravity separation and magnetic separation to construct a multi-stage and composite beneficiation process to cope with various complex ore selection problems.

In the flotation process, by adjusting the reagent system, not only rare earth minerals can be recovered, but also some associated valuable elements in the ore can be recovered simultaneously, improving the overall utilization rate of mineral resources and reducing resource waste.

The flotation method has a good effect on some fine particles (less than 0.5mm or even finer) and complex coexistence of polymetallic ores.

3. Commonly used rare earth flotation equipment

1. Flotation machine

There are various types of flotation machines, including mechanical stirring flotation machines and aeration stirring flotation machines. There are differences between the two in terms of aeration method and agitation intensity control, but the core flotation principle is the same. The mechanical stirring type uses a high-speed rotating impeller to generate a strong stirring effect, so that the slurry and reagents are fully mixed and evenly mixed, and at the same time, air is sucked into the slurry to achieve aeration; then the foam scraping device located on the upper part of the tank is used to regularly scrape the foam on the surface of the slurry to collect the rare earth concentrate.

The ore pulp and flotation reagent are added to the flotation machine tank in a certain order, the stirring device is started, and the impeller rotates at high speed. On the one hand, the ore pulp is stirred into a uniform suspension, which prompts the reagent to disperse quickly and fully contact with the mineral particles, allowing the collector to adsorb on the surface of the rare earth mineral; on the other hand, the rotation of the impeller forms a negative pressure in the central area, sucking in air and cutting it into tiny bubbles. The bubbles collide and adhere with the rare earth minerals that have adsorbed the collector, carrying them to the surface of the ore pulp to form a foam layer, and finally collected by the scraping device. Different types of flotation machines differ in terms of aeration methods, stirring intensity control, etc., but the core flotation principle is the same.

Flotation machine is one of the most commonly used equipment for rare earth ore flotation, and is widely used in all links from roughing to concentrating. In the roughing stage, it can handle a large amount of raw ore pulp, and use strong stirring and aeration capabilities to quickly achieve the initial enrichment of rare earth minerals; in the concentrating stage, by adjusting the amount of reagents added, stirring intensity and other parameters, the rough concentrate is concentrating multiple times, gradually improving the grade of rare earth concentrate to meet industrial production needs.

2. Flotation column

The main body of the flotation column is a slender cylindrical cylinder with closed upper and lower ends. It is generally equipped with a feeding device, a bubble generator, a spray device, a tailings discharge device, etc. The feeding device is located at the top of the cylinder and is used to feed the slurry evenly; the bubble generator is installed at the bottom or lower side of the cylinder and is responsible for generating tiny and uniform bubbles; the spray device is at the top of the cylinder and can spray clean water or adjusters on the surface of the slurry to assist flotation; the tailings discharge device is at the bottom of the cylinder and is used to discharge the gangue mineral tailings that have not floated up.

The slurry is fed from the top of the cylinder and flows slowly downward under the action of gravity. At the same time, the bubbles generated by the bubble generator pass through the slurry from bottom to top. Since the rare earth minerals are hydrophobic after being treated with the collector, they quickly attach to the bubbles and float up with the bubbles during the reverse contact process with the bubbles, forming a foam layer that gathers at the top of the cylinder and is collected by a special collection device; while the gangue minerals continue to flow downward due to hydrophilicity and are eventually discharged from the tailings discharge device at the bottom. The flotation column uses the countercurrent contact principle to extend the contact time between the mineral and the bubble, improve the flotation efficiency, and its structure is relatively simple and has low energy consumption.

Flotation columns are often used in the selection process of rare earth ore beneficiation, especially for some situations where the concentrate grade is extremely high. After the rough concentrate is roughly selected by the flotation machine, it enters the flotation column for further selection. With its efficient sorting performance, it removes a small amount of residual gangue minerals and improves the grade of rare earth concentrate to a higher level to meet the production requirements of high-end rare earth products.

Rare earth ore flotation technology has become an important means to achieve efficient and high-grade selection in the field of rare earth ore beneficiation by accurately controlling the surface properties of minerals and relying on innovative equipment such as flotation machines and flotation columns. With the continuous progress in related fields such as materials science and pharmaceutical research and development, the rare earth ore flotation process and equipment will continue to innovate and optimize, pushing the rare earth industry to a higher level.