1. What effect does grinding grain size have on flotation?
The coarse ore particles (greater than 0.1 mm) and the extremely fine ore particles (less than 0.006 mm) at the time of flotation are not well floated and the recovery rate is low.
In the case of flotation coarse particles, the exfoliation force of the ore particles is increased due to the large weight. Then it is necessary to: (1) use a sufficient amount of the most effective collector ; (2) increase the aeration of the slurry, cause larger bubbles, and increase the amount of microbubbles precipitated in the water; (3) the mixing strength of the slurry should be appropriate; (4) It is necessary to increase the concentration of the slurry properly; (5) The scraper should be quickly and smoothly scraped.
In the flotation of very fine particles (usually referred to as less than 5 to 10 μm of slime), (1) due to the small mass of the slime, it is easy to adhere to the surface of the coarse particles, so that the floatability of the coarse particles is reduced, and the selectivity is changed. (2) Because the slime is larger than the surface, they will adsorb a large amount of flotation agent in the slurry, which will reduce the concentration of the agent in the slurry, destroy the normal flotation process and reduce the flotation index; (3) The slime has a very fine surface area, so that the surface activity is increased, it is easy to work with various chemicals, it is difficult to sort, and it has strong hydration, so that the foam is excessively stable, and the selection will cause difficulty and reduce the fineness. The quality of the ore and the foam product flow and concentration efficiency are reduced.
2. How to prevent and reduce the excessive amount of slime in the grinding ore slurry?
Common ways to prevent and mitigate slime are:
(1) Reduce and prevent the formation of slime: multi-stage grinding process and stage mineral processing . To properly select grinding and grading equipment to improve the efficiency of the classifier;
(2) Adding agents to eliminate the harmful effects of slime: commonly used water glass, soda, caustic soda, etc.; can reduce the flocculation and cover function of the slime. In order to alleviate the harmful effects of a large amount of adsorbent on the slime, a segmented dosing method may be considered;
(3) Desliming the ground ore before flotation, and discarding it as tailings. If the content of useful components in the slime is high, the removed slime can also be floated separately or sent to water and metallurgy.
Commonly used desliming methods: 1 classifier de-sludge; 2 hydrocyclone de-sludge; 3 under special circumstances, a small amount of foaming agent can be added before flotation, and the easy-floating mud can be removed by flotation.
3. Why is the coarse grain difficult to float, what process should be taken?
Rough grinding saves grinding costs and reduces costs. In the flotation plant that processes unevenly embedded ore, under the premise of ensuring the crude recovery rate, there is a tendency to put coarse grinding fineness. However, since the coarse particles are relatively heavy, they are not easily suspended in the flotation machine, and the chance of collision with the bubbles is reduced. Further, after the coarse particles adhere to the air bubbles, they are easily detached from the air bubbles due to the large peeling force. Therefore, the coarse particles have a poor flotation effect under the general process conditions. In order to improve the effect of coarse flotation, the following technological measures can be taken:
(1) a strong force collector collector may also be supplemented with kerosene, diesel oil and other auxiliary collector, to strengthen the coarse collectors, the ability to increase the adhesion of the mineral particles with the bubbles and adhesion, reduced Fall off.
(2) Appropriately increase the mass fraction of the slurry and increase the buoyancy of the slurry. Under the premise of ensuring the stability of the foam layer, the mixture is appropriately stirred to promote the suspension of the coarse particles, and the chance of adhesion to the bubbles is increased.
(3) Appropriately increase the aeration volume of the flotation machine, causing large bubbles and forming a "floating group" composed of large and small bubbles. This "floating group" has a large buoyancy and can carry coarse particles. Going up.
(4) Using a shallow trough flotation machine to shorten the distance of mineralized bubbles and reduce the loss of ore particles from the bubbles. Or use a special flotation machine suitable for coarse flotation, such as an annular flotation machine and a Skennaer flotation machine.
(5) Adopt a rapid and smooth foaming device to scrape the floating mineralized foam in time to reduce the re-shedting of the ore.
4. What are the reasons for the difficulty in fine flotation and the technical measures taken?
Flotation separation of fine-grained materials is difficult, mainly for the following reasons:
(1) The specific surface area of ​​the fine particles is large, and the surface energy is remarkably increased. Under certain conditions, non-selective mutual condensation between the surfaces of different minerals is prone to occur. On the other hand, it is also because the surface energy of the fine particles is large, and although the adsorbing power is high for the agent, the poor adsorption property is selected, which makes it difficult for the fine particles to be selectively separated.
(2) The fine particles are small in volume and are less likely to collide with bubbles. The fine particles have a small mass, and when they collide with the bubbles, it is difficult to overcome the resistance of the hydration layer between the ore particles and the bubbles, and it is difficult to adhere to the bubbles.
The technical measures to solve the fine flotation are as follows:
(1) Selective flocculation flotation. The flocculant is used to selectively flocculate the target mineral particles or gangue fines, and then separated by flotation.
(2) Carrier flotation. The target mineral fine particle cover is floated on the carrier by using the general flotation granular grade ore as a carrier. The carrier may be of the same type or a heterogeneous mineral. For example, it can be used as a carrier pyrite flotation of fine gold. The calcite is used as a carrier to float the fine iron and titanium impurities in the kaolin .
(3) Agglomeration flotation, also known as emulsification flotation. After the fine-grained mineral is treated by the collector, it forms an oily foam with ore under the action of a neutral oil. The collector and neutral oil can be first formulated into an emulsion and then added to the slurry. Neutral oil and collector can also be added to the high quality fraction (70% solids) pulp, stirred vigorously, controlled for time, and then scraped off the upper layer of foam. This method has been used to fine manganese ore, ilmenite and apatite and the like.
5. How does the slime affect the flotation?
If the flotation slurry contains more slime, it will bring a series of adverse effects on flotation. The main influences are as follows: 1 It is easy to be mixed in the foam product, which makes the concentrate grade drop. 2 easy to cover the coarse grain surface, affecting the flotation of coarse particles. 3 adsorption of a large number of agents, increase drug consumption. 4 The pulp is sticky and the aeration conditions are deteriorated.
The technical measures to solve this problem are as follows: (1) The use of a relatively thin pulp to reduce the viscosity of the slurry can reduce the inclusion of the slime in the foam product. 2 Add dispersant to disperse the slime and eliminate the harmful effects of the cover on other mineral surfaces. 3 sections are added in batches to reduce the consumption of chemicals by the slime. 4 The flotation material is preliminarily delimed and then floated. A commonly used desliming method is a cyclone degrading.
6. What is the main impact of air on flotation?
In addition to oxygen, nitrogen and inert gases, there are carbon dioxide and water vapor in the air.
Air has an effect on the floatability of minerals:
(1) When the mineral breaks out to reveal a fresh surface, it undergoes hydration in the presence of water and is hydrophilic. However, when the gas is adsorbed to the surface of the mineral, the hydration is weakened, resulting in a preliminary hydrophobicity of the surface.
(2) Gas and mineral surface applications are selective. Among them, oxygen is a major influence on the mineral surface.
(3) The role of oxygen is beneficial to the hydrophobicity of the cut-off of the sulfide ore. However, if the action time is too long, the mineral surface will return to hydrophilicity. When the gas adsorption conditions are appropriate, it will cause the hydrophobicity of the mineral surface, even if it is not added to the flotation agent (for example, dry coal powder). And galena also only after preliminary action of oxygen can occur with xanthate and floating effect.
7. What is the role of pulp mixing?
The agitation of the slurry can promote the suspension of the ore particles and evenly disperse in the tank; it can promote the good dispersion of the air and make it evenly distributed in the tank; it can promote the enhanced dissolution of air in the high pressure area of ​​the tank, and strengthen the precipitation in the low pressure area. To cause a large amount of active microbubbles.
Intensification of aeration and agitation is advantageous for flotation, but not excessive, because excessive aeration and agitation will have the following disadvantages: (1) promote the merger of bubbles, (2) reduce the quality of concentrate, and (3) increase the power consumption. (4) increased the wear of various parts of the flotation machine, (5) the volume of the slurry in the tank is reduced (this is because the volume of the tank is increased by the portion occupied by the bubble), and (6) excessive stirring can also adhere to the bubble. The mineral particles fall off.
The optimum amount of aeration and agitation in production should be determined by experimentation depending on the type and structural characteristics of the flotation machine.
8. What effect does the slurry concentration have on the flotation index?
The slurry concentration can affect the following technical and economic indicators: (1) affecting the recovery rate. When the slurry concentration is small, the recovery rate is low. As the concentration of the slurry increases, the recovery rate also increases, but the recovery rate exceeds the limit. The main reason is that the concentration is too high, which destroys the aeration condition of the flotation machine.
(2) Affect the quality of concentrates. The general rule is that the quality of the concentrate is higher when flotation is carried out in a leaner slurry, while the quality of the concentrate is reduced when it is floated in a thicker slurry.
(3) affecting the consumption of pharmaceuticals. When the slurry is thicker, the amount of treatment per t ore is less, and when the concentration of the slurry is thinner, the amount of treatment per t ore is increased.
(4) Affect the production capacity of the flotation machine. As the concentration of the slurry increases, the production capacity of the flotation machine calculated according to the treatment amount also increases.
(5) Affecting water and electricity consumption. The thicker the pulp, the smaller the water and electricity consumption per t ore.
(6) When affecting flotation. When the flotation slurry is thicker, the flotation time is slightly increased.
In short, when the concentration of the slurry is rich, it is beneficial to the flotation process. However, if the slurry and bubbles do not flow freely, the aeration will deteriorate, thereby reducing the quality and recovery. In this case, the various ore sections of the flotation should determine the appropriate concentration of the slurry according to the nature of the ore and relevant technical requirements.
9. What is the relationship between pulp concentration and flotation conditions and ore properties?
The optimum slurry concentration during flotation is determined by the ore properties and flotation conditions. The general rule is:
(1) The mineral with large flotation density uses a thicker slurry, while the mineral with a small flotation density uses a thinner slurry;
(2) Flotation of coarse-grained materials with thicker slurry, flotation of fine-grained and muddy materials with thinner ore.
(3) The use of coarser slurry for rough selection and sweeping can reduce the consumption of chemicals and the number of flotation machines, while the selection uses thinner pulp to obtain higher quality Taige concentrate.
When the ore is coarsely selected, the slurry concentration is 25% to 35%, and the flotation fine particles and the ore containing high mud are 10% to 20%.
10. What is the impact of pulp quality score on flotation?
The pulp mass fraction is an important process factor for flotation and has a significant impact on flotation. There are two ways to express the mass fraction of pulp: 1 liquid-solid ratio, which represents the ratio of liquid to solid mass (or volume) in the slurry. This method of representation is very convenient when calculating the slurry flow. 2 Percentage (%) of solid content, which represents the percentage of solid mass (or volume) in the slurry. This method of representation is widely used in mineral processing experiments and production.
The main effects of pulp quality score on flotation have the following aspects:
(1) Recovery rate. Within a certain range, when the pulp mass fraction is low, the recovery rate is low; the pulp mass fraction increases, and the recovery rate increases accordingly. However, the mass fraction of the slurry should not be too large. If it is too large, the flotation machine is difficult to inflate normally in the slurry, which in turn reduces the recovery rate.
(2) Concentrate grade. The general rule is that the concentrate grade is higher when flotation is carried out in a leaner slurry, while the concentrate grade is reduced when it is floated in a thicker slurry.
(3) dosage of the agent. The flotation agent should maintain a certain mass fraction in the pulp to have a good flotation effect. When the pulp is thicker, the mass fraction of the medicament is correspondingly increased, that is, the required medicament mass fraction can be achieved with a smaller amount of the medicament, and the amount of the medicament per t ore is correspondingly reduced. On the other hand, when the pulp is thinner, the amount of the agent increases.
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