Does ore particle size affect flotation in mineral processing effect?

For flotation in mineral processing, ore particle size (also known as grinding fineness) is an important factor affecting the final flotation index. The practice shows that the suitable particle size generally refers to that more than 80% of the useful minerals have been dissociated by monomers. If the ore particles are too coarse or too fine, even if they have reached the state of monomer dissociation, the flotation effect is not ideal.

In the flotation in mineral processing, why is it difficult to float if the ore particles are too coarse or too fine? What measures should we take to solve this problem?

Why is it difficult to float if the ore particle is too coarse? How to solve it?

For some unevenly distributed ores, the grinding cost is high and the ore is easy to over grind, so the coarse grinding flotation process is often used. However, the coarse particles are relatively heavy and are not easy to suspend in the flotation machine, so the chance of collision with bubbles is reduced, and the coarse particles are easy to fall off from bubbles due to large falling force after they are attached to bubbles. Therefore, under general process conditions, the effect of coarse particle flotation is poor.

Solution:
1. Improve pharmaceutical system
The collector with strong collector force is selected and the collector concentration is reasonably increased in order to enhance the adhesion strength between minerals and bubbles and accelerate the flotation speed. In addition, adding non-polar oil, such as diesel oil and kerosene, can “consolidate” the three-phase contact periphery and enhance the fixation density of minerals and bubbles.

2. Correctly select and adjust flotation equipment
Reducing the turbulence intensity of pulp movement in the flotation machine is the key to ensure coarse particle flotation.
On the one hand, the shallow cell flotation machine is used to shorten the flotation distance of mineralized bubbles and reduce the falling off of ore particles from bubbles, or a special flotation machine suitable for coarse particle flotation, such as CLF coarse particle flotation machine. On the other hand, the air volume of the flotation machine should be increased properly to generate larger bubbles and form a “floating cluster” formed by large and small bubbles. This “floating group” has larger buoyancy, which can carry coarse particles to float, or adopt a quick and steady foam scraping device, and timely scrape up the floating floating mineralized foam, so as to reduce the re emergence of ore particles.

3. Properly increase the pulp concentration
Properly increasing the pulp concentration can increase the buoyancy of the pulp. The pulp concentration of general metal mineral roughing is 25-45%, and the upper limit can reach 50-55%; The concentration of selected pulp is 10-20%, and the lower limit can reach 6-8%; The concentration of sweeping pulp is 20-40%.

Why is it difficult to float if the ore particle is too fine? How to solve it?

Flotation separation of fine materials is often difficult for the following reasons:
1. The specific surface area of fine particles is large, and the surface energy increases significantly. Non selective condensation is easy to occur between the surfaces of different minerals. Due to the large surface energy of fine particles, although they have high adsorption capacity for reagents, their selective adsorption is poor, so it is difficult to separate fine particles selectively.
2. The volume of fine particles is small and the possibility of collision with bubbles is small, which reduces the flotation rate. The fine particles are of small quality, and it is difficult to overcome the resistance of the hydration layer between the ore particles and the bubbles when colliding with the bubbles, so it is difficult to adhere to the bubbles.
3. The surface dissolution rate of fine-grained minerals increases, and the “inevitable ions” in the pulp increase.
4. The specific surface area of fine material is large, which increases the consumption of reagent.

Solution:
1. Selective flocculation flotation
Flocculant is used to selectively flocculate target mineral particles or gangue fine mud, which is generally used for fine hematite flotation.
2. Select the flotation reagent
The flotation reagent with chemical adsorption or chelation operation for fine-grained minerals is selected to improve the flotation speed of fine-grained minerals.
3. Carrier flotation
The ore particles suitable for flotation particle size are used as the carrier to float the target fine particles on the carrier. The carrier can use similar minerals or heterogeneous minerals. For example, pyrite is used as carrier to float fine gold; Calcite was used as carrier to float fine iron and titanium impurities from kaolin.
4. Agglomeration flotation (emulsion flotation) is adopted
Finely grained minerals are treated by collector and formed oil bearing foam with neutral oil. The collector can be mixed with neutral oil into the emulsion and added to the pulp. Neutral oil and collector can also be added to the slurry with high concentration (solid content of 70%), and the mixture is strongly stirred to control the time, and then the upper foam is scraped out. This method is suitable for the flotation of fine manganese ore, ilmenite and apatite ore.
5. Micro bubble flotation
That is, reducing the bubble size is conducive to increasing the gas-liquid interface and increasing the collision and adhesion probability between fine particles, mainly including electrolytic flotation and vacuum flotation.

At present, the suitable particle size range for flotation is usually 0.01-0.1mm. The flotation upper limit particle size of sulfide minerals is generally 0.2-0.25mm, and that of oxidized minerals is 0.25-0.3mm. For some non-metallic ores with small density, the upper limit of flotation particle size can be increased to 0.5-1mm. In production, the appropriate particle size shall be determined according to the embedded particle size of useful minerals in beneficiation test, so as to minimize the continuum between useful minerals and gangue minerals, and avoid arbitrary application.

 

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