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Flotation is one of the commonly used methods for silica sand beneficiation. It is mainly used to remove mica and feldspar minerals that are symbiotic with silica sand. However, in the actual production process, the flotation process will be affected by many factors, including:
feed size
slurry temperature
slurry liquid chemical composition
flotation reagents
other flotation conditions
This article will introduce the impact of these 5 factors on silica sand flotation and their solutions.
Usually, crushing and grinding operations are carried out before the silica sand flotation operation, one is to make the ore to achieve monomer separation, and the other is to prepare the particle size suitable for flotation. Too large silica sand particles will result in insufficient capacity of the bubbles generated by the flotation reagent to carry silica sand particles, which will affect the flotation effect.
For the flotation of coarser silica sand, the following methods can be used:
(1) Use powerful collectors to improve the hydrophobicity of silica sand particles;
(2) Add water-insoluble oily flotation chemical as auxiliary collector to increase the adhesion strength of mineral particles and bubbles;
(3) Using the combined flotation method, several small bubbles are combined with each other to complete the coarse silica sand flotation;
(4) Removal of fine mud;
(5) Shorten the path of rising bubbles;
(6) Create a stable bubble layer, and use a flotation machine with a meticulous operation and a rapid bubble scraping mechanism.
The above is the case when processing coarse-grained silica sand. On the contrary, when processing fine-grained silica sand, it is necessary to remove the fine mud in advance. Because commonly, fine mud can reduce the flotation recovery rate, lower the concentrate grade and the flotation speed, and also increase the consumption of flotation reagents.
In order to solve the influence of fine mud on silica sand flotation, the following methods can be used to remove the fine mud:
(1) Fully desliming;
(2) Add fine mud dispersant to the slurry to prevent the mud from covering the selected silica sand minerals and bubbles;
(3) Dilute the slurry concentration to reduce the chance of mixing fine mud in the foam;
(4) In the whole process of flotation, add collectors in batches to keep the concentration of reagent in the slurry unchanged and reduce the adsorption of fine mud;
(5) The ultrafine particle flotation method is adopted, and the carrier minerals are used to make the fine mud attached to the carrier and actively float the white mud.
In addition to the feed size that affects the flotation effect, the slurry temperature also has a significant effect on the flotation effect. Usually when the temperature of the slurry rises, the floatation rate will increase, but the selectivity will become worse. But there is one exception. When fatty acids and soap are used as flotation reagents, increasing the slurry temperature can improve selectivity and increase floatation rate.
Normally, the silica sand flotation effect is best when the maintained slurry temperature is 40～45℃.
Silica sand flotation operations also have certain requirements for the water used. Hard water contains more dissolved minerals (such as Ca2+, Mg2+, Fe3+, etc.). These metal ions will destroy or consume some flotation reagents. Therefore, deionized water and soft water are generally better. When flotation is carried out under the same conditions, if one time goes well, but the other time is not good, it is necessary to study the influence of water.
In order to adjust the influence of the liquid phase composition of the slurry, here are some feasible methods:
(1) Minimize the contact time between water and crushed ore
(2) Choose the appropriate flotation reagent and flotation machine to increase the flotation speed
(3) Reduce the amount of medium ore circulation
(4) Use EDTA(Ethylenediaminetetraacetic acid chemical) to remove harmful ions
(5) Use pH adjuster
(6) Using ion flotation
The collector can make the surface of the target mineral or the mineral to be removed hydrophobic, thereby increasing its floatability, so that the selected material is attached by bubbles and floats out of the slurry. The regulator mainly adjusts the conditions of the slurry medium and enhances the strength of the collector. The foaming agent mainly promotes the generation of bubbles in the pulp, thereby enhancing the bearing capacity of the foam on minerals, and better floating minerals from the pulp.
In the neutral slurry, anion and cation mixed collectors, feldspar activators and silica sand inhibitors can be used to preferentially flotate impurities such as feldspar to achieve effective separation of impurities such as silica sand and feldspar.
In the alkaline slurry, the silica sand can be activated by metal ions as the activator, and then the anion collector is preferably used to flotate the silica sand to achieve effective separation of impurities such as silica sand and feldspar.
In addition to the several influencing factors mentioned above, the influence of weathering is also a big factor that influence the silica sand flotation. Since the surface of the silica sand particles separated from the monomer is sometimes polluted by metamorphic substances, it is required to carry out sufficient friction grinding or ore washing to purify the surface before being used for flotation.
In addition to the influencing factor of silica sand weathering, the mixing time will also affect the flotation effect, because when the mixing time is too long, sometimes the collector adsorbed on the mineral surface will be removed due to physical action, resulting in the collector Increase in dosage. If the mixing time is too short, the pulp and the flotation chemical will not be fully mixed. Therefore, when processing silica sand, generally reduce the mixing time in the order of fatty acid, sulfonate and amine.
The 5 factors that affect the silica sand flotation process are introduced above: feed size, pulp temperature, chemical composition of the pulp liquid phase, flotation reagents and other flotation conditions. Before putting it into production, it is necessary to make a good flotation plant design under the premise of fully considering these factors.
If you want to know more about the silica sand flotation process and equipment, please leave a message or consult online customer service for more information.
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