There are many process factors affecting the flotation process, among which the most important ones are: (1) particle size (grinding fineness); (2) pulp concentration; (3) chemical addition and adjustment; (4) adjustment of bubbles and foam; 5) slurry temperature; (6) flotation process; (7) water quality.
Experience has shown that the flotation process factors must be determined and selected according to the characteristics of the ore properties and through experimental research in order to obtain the best technical and economic indicators.
Particle size In order to ensure high process index for flotation, it is of great significance to study the effect of ore size on flotation and to determine the optimum particle size (fineness) and other process conditions according to the nature of the ore.
(I) Effect of Particle Size on Flotation Flotation requires not only the dissociation of minerals, but also the appropriate inclusion size. The ore is too thick, and even if the mineral has been dissociated from the monomer, it often cannot be floated because it exceeds the buoyancy of the bubble. Different flotation size limit for minerals, such as sulphide minerals is usually 0.2 to 0.25 mm, the non-sulfide minerals from 0.25 to 0.3 mm, for some of the less dense non-metallic mineral, such as coal, the upper limit of the particle size can also be improved. However, too fine a fine grain size (e.g., less than 0.01 mm) is also detrimental to flotation. Practice has shown that the flotation behavior of various granularities is different.
The data in the table indicates that different minerals have their optimal flotation particle size range. Too coarse (greater than 0.1 mm) and too fine (greater than 0.006 mm) are not conducive to flotation and the recovery is reduced.
Timely measurement of the change of the graded overflow fineness can provide a basis for the grinding classification operation. In the case of no automatic measurement of particle size and automatic adjustment, rapid screening analysis can be generally used. The site shall be measured every 1~2 hours according to the regulations. If the fineness is not satisfactory, the operating conditions of the grinding and classifying equipment shall be changed in time, for example, adjusting the feeding rate of the mill, the overflow concentration of the classifier, and the grinding concentration.
Timely inspection of the particle size composition of flotation concentrates and tailings, as well as changes in grinding fineness, such as increased coarse-grained loss in tailings, then slipping "running rough", indicating that grinding fineness is not enough; if metal The main loss at the fine-grain level indicates that it has been over-grinded and should be properly coarse-ground and reinforced.
Both coarse and ultrafine (sludge) have many special physical and physicochemical properties, their flotation behavior and general grain size (0.001 (II) Process measures for coarse flotation Under the premise of dissociation of ore particles, coarse grinding flotation can save grinding costs and reduce beneficiation costs. When handling uneven disseminated ore porphyry copper mining and large, to ensure the recovery roughing premise, there is a tendency for the coarse grinding of flotation. However, since the coarser ore is relatively heavy, it is less likely to be suspended in the flotation machine, and the probability of collision with the bubble is reduced, and the adhesion force is large after the bubble is attached, and it is easy to fall off. Therefore, under the general process conditions, the coarse-grained ore particles have a poor flotation effect. In order to improve the flotation of coarse particles, the following special process conditions can be employed.
Selection and adjustment of A flotation machine The practice has proved that the strong turbulent movement of the slurry in the mechanical agitating flotation machine is the main factor that causes the ore particles to fall off the bubble. Therefore, reducing the turbulence intensity of slurry movement is the fundamental measure to ensure coarse flotation. To this end, measures can be taken according to the specific conditions: (1) Select a special flotation machine suitable for flotation coarse particles, such as an annular flotation machine (China), a skinair type flotation machine (Finland) , foam sorting and fluidized flotation machine (former Soviet Union), etc.; (2) improve and adjust the structure and operation of conventional flotation machines, such as: properly reduce the groove depth (using shallow groove type), shorten the mineralized bubbles Lifting distance to avoid the falling off of the ore; adding a sieve above the impeller area to weaken the turbulent intensity of the slurry, keeping the foam area stable; increasing the aeration amount and forming more large bubbles, which is conducive to the formation of floating clusters composed of bubbles and ore particles The coarse grain is “arched up†and floated; the foaming is quick and stable.
B Appropriately increase the concentration of pulp C Improve the chemical system Select a collector with strong harvesting force and increase the concentration of the agent reasonably, in order to enhance the fixation strength of minerals and bubbles, accelerate the rising speed, and add non-polar oil, such as Auxiliary collectors such as diesel oil and kerosene can “consolidate†the three-phase contact perimeter and enhance the anchoring strength of minerals and bubbles.
(III) Process measures for fine particle flotation Fine particles generally refer to slime less than 18 microns or less than 10 microns. Due to the small mass and large specific surface area of ​​the fine-grained ore (mineral mud), a series of special behaviors of the ore during the pulping and flotation process are caused: [next]
From the action of particles and particles, due to the significant enhancement of the surface energy of the particles, under certain conditions, mutual coagulation between different mineral particles is easy to form non-selective aggregation, and the particles tend to adhere to the surface of the coarse particles to form a slime cover;
From the action of the particles and the medium, the particles have a large specific surface area and surface energy, and therefore, have high drug adsorption capacity, poor adsorption selectivity; increased surface solubility, which makes the pulp "inevitable ion" increase; small mass is easy to be water flow Mechanical entrainment and mechanical entrainment of foam;
From the action of particles and bubbles, the contact efficiency of the bubbles decreases due to the decrease in contact efficiency and adhesion efficiency, and the "armor" phenomenon of the mud which generates bubbles at the same time affects the carrying amount of the bubbles.
All of the above-mentioned behaviors are the main reasons leading to slower flotation speed, selective deterioration, lower recovery rate and marked deterioration of flotation index.
In order to reduce and prevent the harmful effects of slime and strengthen fine flotation, the following process measures are often used in modern flotation practice:
(1) Eliminate and prevent the interference of slime on the flotation process. The main measures are:
1) Desliming This is a way to eradicate the effects of slime. Graded desilting is the most commonly used method. For example, a hydrocyclone is used to separate a certain grade of slurry before flotation, or it is discarded or treated separately with coarse mud. For some easy-to-float slime, a small amount of foaming agent can be pre-flotted and removed before flotation.
2) adding the sludge dispersant sludge sufficiently dispersed can eliminate harmful effects generated between "sludge cover" non-selective phenomena and mutual coagulation of particles, conventional sludge dispersants are: sodium silicate, sodium hexametaphosphate Sodium and so on.
3) Adding the pesticide in batches in batches, which can maintain the effective concentration of the agent in the slurry and increase the selectivity.
4) Reducing the concentration of flotation pulp to reduce the concentration of flotation pulp, on the one hand, it can reduce the sludge contamination of concentrate concentrate; on the other hand, it can also reduce the viscosity of the slurry.
(2) Selecting a collector that has chemisorption or chelation of particulate minerals to facilitate the selectivity of the flotation process.
(3) Applying physical or chemical methods to increase the apparent particle size of particulate minerals and increase the flotation rate and selectivity of the minerals to be sorted. The new processes developed according to this principle in recent times include:
1) Select flocculation flotation Use the flocculant to selectively flocculate the target mineral or gangue slime, and then separate by flotation. This method has been used in the flotation of fine-grained hematite (US Tilden processing plant).
2) Carrier flotation The fine particles of the general flotation grade are used as a carrier, and the fine particles are covered on the carrier, and then floated together with the carrier. The carrier may be a similar carrier (mineral) or a heterogeneous carrier (mineral).
3) Agglomeration flotation Also known as emulsification flotation, fine-grained minerals are treated with a collector and form a mineral-like oily foam under the action of a neutral oil. This method has been used for sorting of manganese ore fines, the titanium ore, apatite. The operating process conditions are divided into two categories: one is that the collector and the neutral oil are first formulated into an emulsion, and the second is in a high concentration slurry (70% solids), which is added with a neutral oil and a collector. Stir vigorously.
(4) Reducing the particle size of the bubbles to achieve microbubble flotation Under certain conditions, reducing the particle size of the bubbles not only increases the gas-liquid interface, but also increases the collision probability of the particles. And the probability of adhesion, favoring the flotation of hand particle minerals. The main processes are:
1) Vacuum flotation A vacuum flotation method in which microbubbles are precipitated from a solution by a pressure reducing device, and the particle diameter of the bubbles is generally 0.1 to 0.5 mm. Studies have shown that it is effective to precipitate fine-grained fine-grained barite , fluorite , quartz, etc. from water. When other conditions are the same, the conventional flotation method, the grade of barite concentrate is 54.4%, the recovery rate is 30.6%, and the vacuum flotation grade can be increased to 53.6~63.6%, and the corresponding recovery rate is 52.9~45.7. %.
2) Electrolytic flotation The microbubbles are obtained by the method of electrolyzing water. The general bubble size is 0.02~0.06 mm. When used for flotation of fine cassiterite , the flotation of electrolytic hydrogen bubbles is used alone. The recovery rate of coarse selection is higher than that of conventional flotation. Significantly improved from 35.5% to 79.5%, while the grade increased by 0.8%.
In addition, research on other new processes has been carried out in recent years, such as controlling dispersion flotation, branch flotation, etc. for iron ore and black tungsten fine mud flotation, all of which have achieved good results.
Experience has shown that the flotation process factors must be determined and selected according to the characteristics of the ore properties and through experimental research in order to obtain the best technical and economic indicators.
Particle size In order to ensure high process index for flotation, it is of great significance to study the effect of ore size on flotation and to determine the optimum particle size (fineness) and other process conditions according to the nature of the ore.
(I) Effect of Particle Size on Flotation Flotation requires not only the dissociation of minerals, but also the appropriate inclusion size. The ore is too thick, and even if the mineral has been dissociated from the monomer, it often cannot be floated because it exceeds the buoyancy of the bubble. Different flotation size limit for minerals, such as sulphide minerals is usually 0.2 to 0.25 mm, the non-sulfide minerals from 0.25 to 0.3 mm, for some of the less dense non-metallic mineral, such as coal, the upper limit of the particle size can also be improved. However, too fine a fine grain size (e.g., less than 0.01 mm) is also detrimental to flotation. Practice has shown that the flotation behavior of various granularities is different.
The data in the table indicates that different minerals have their optimal flotation particle size range. Too coarse (greater than 0.1 mm) and too fine (greater than 0.006 mm) are not conducive to flotation and the recovery is reduced.
Timely measurement of the change of the graded overflow fineness can provide a basis for the grinding classification operation. In the case of no automatic measurement of particle size and automatic adjustment, rapid screening analysis can be generally used. The site shall be measured every 1~2 hours according to the regulations. If the fineness is not satisfactory, the operating conditions of the grinding and classifying equipment shall be changed in time, for example, adjusting the feeding rate of the mill, the overflow concentration of the classifier, and the grinding concentration.
Timely inspection of the particle size composition of flotation concentrates and tailings, as well as changes in grinding fineness, such as increased coarse-grained loss in tailings, then slipping "running rough", indicating that grinding fineness is not enough; if metal The main loss at the fine-grain level indicates that it has been over-grinded and should be properly coarse-ground and reinforced.
Both coarse and ultrafine (sludge) have many special physical and physicochemical properties, their flotation behavior and general grain size (0.001
Selection and adjustment of A flotation machine The practice has proved that the strong turbulent movement of the slurry in the mechanical agitating flotation machine is the main factor that causes the ore particles to fall off the bubble. Therefore, reducing the turbulence intensity of slurry movement is the fundamental measure to ensure coarse flotation. To this end, measures can be taken according to the specific conditions: (1) Select a special flotation machine suitable for flotation coarse particles, such as an annular flotation machine (China), a skinair type flotation machine (Finland) , foam sorting and fluidized flotation machine (former Soviet Union), etc.; (2) improve and adjust the structure and operation of conventional flotation machines, such as: properly reduce the groove depth (using shallow groove type), shorten the mineralized bubbles Lifting distance to avoid the falling off of the ore; adding a sieve above the impeller area to weaken the turbulent intensity of the slurry, keeping the foam area stable; increasing the aeration amount and forming more large bubbles, which is conducive to the formation of floating clusters composed of bubbles and ore particles The coarse grain is “arched up†and floated; the foaming is quick and stable.
B Appropriately increase the concentration of pulp C Improve the chemical system Select a collector with strong harvesting force and increase the concentration of the agent reasonably, in order to enhance the fixation strength of minerals and bubbles, accelerate the rising speed, and add non-polar oil, such as Auxiliary collectors such as diesel oil and kerosene can “consolidate†the three-phase contact perimeter and enhance the anchoring strength of minerals and bubbles.
(III) Process measures for fine particle flotation Fine particles generally refer to slime less than 18 microns or less than 10 microns. Due to the small mass and large specific surface area of ​​the fine-grained ore (mineral mud), a series of special behaviors of the ore during the pulping and flotation process are caused: [next]
From the action of particles and particles, due to the significant enhancement of the surface energy of the particles, under certain conditions, mutual coagulation between different mineral particles is easy to form non-selective aggregation, and the particles tend to adhere to the surface of the coarse particles to form a slime cover;
From the action of the particles and the medium, the particles have a large specific surface area and surface energy, and therefore, have high drug adsorption capacity, poor adsorption selectivity; increased surface solubility, which makes the pulp "inevitable ion" increase; small mass is easy to be water flow Mechanical entrainment and mechanical entrainment of foam;
From the action of particles and bubbles, the contact efficiency of the bubbles decreases due to the decrease in contact efficiency and adhesion efficiency, and the "armor" phenomenon of the mud which generates bubbles at the same time affects the carrying amount of the bubbles.
All of the above-mentioned behaviors are the main reasons leading to slower flotation speed, selective deterioration, lower recovery rate and marked deterioration of flotation index.
In order to reduce and prevent the harmful effects of slime and strengthen fine flotation, the following process measures are often used in modern flotation practice:
(1) Eliminate and prevent the interference of slime on the flotation process. The main measures are:
1) Desliming This is a way to eradicate the effects of slime. Graded desilting is the most commonly used method. For example, a hydrocyclone is used to separate a certain grade of slurry before flotation, or it is discarded or treated separately with coarse mud. For some easy-to-float slime, a small amount of foaming agent can be pre-flotted and removed before flotation.
2) adding the sludge dispersant sludge sufficiently dispersed can eliminate harmful effects generated between "sludge cover" non-selective phenomena and mutual coagulation of particles, conventional sludge dispersants are: sodium silicate, sodium hexametaphosphate Sodium and so on.
3) Adding the pesticide in batches in batches, which can maintain the effective concentration of the agent in the slurry and increase the selectivity.
4) Reducing the concentration of flotation pulp to reduce the concentration of flotation pulp, on the one hand, it can reduce the sludge contamination of concentrate concentrate; on the other hand, it can also reduce the viscosity of the slurry.
(2) Selecting a collector that has chemisorption or chelation of particulate minerals to facilitate the selectivity of the flotation process.
(3) Applying physical or chemical methods to increase the apparent particle size of particulate minerals and increase the flotation rate and selectivity of the minerals to be sorted. The new processes developed according to this principle in recent times include:
1) Select flocculation flotation Use the flocculant to selectively flocculate the target mineral or gangue slime, and then separate by flotation. This method has been used in the flotation of fine-grained hematite (US Tilden processing plant).
2) Carrier flotation The fine particles of the general flotation grade are used as a carrier, and the fine particles are covered on the carrier, and then floated together with the carrier. The carrier may be a similar carrier (mineral) or a heterogeneous carrier (mineral).
3) Agglomeration flotation Also known as emulsification flotation, fine-grained minerals are treated with a collector and form a mineral-like oily foam under the action of a neutral oil. This method has been used for sorting of manganese ore fines, the titanium ore, apatite. The operating process conditions are divided into two categories: one is that the collector and the neutral oil are first formulated into an emulsion, and the second is in a high concentration slurry (70% solids), which is added with a neutral oil and a collector. Stir vigorously.
(4) Reducing the particle size of the bubbles to achieve microbubble flotation Under certain conditions, reducing the particle size of the bubbles not only increases the gas-liquid interface, but also increases the collision probability of the particles. And the probability of adhesion, favoring the flotation of hand particle minerals. The main processes are:
1) Vacuum flotation A vacuum flotation method in which microbubbles are precipitated from a solution by a pressure reducing device, and the particle diameter of the bubbles is generally 0.1 to 0.5 mm. Studies have shown that it is effective to precipitate fine-grained fine-grained barite , fluorite , quartz, etc. from water. When other conditions are the same, the conventional flotation method, the grade of barite concentrate is 54.4%, the recovery rate is 30.6%, and the vacuum flotation grade can be increased to 53.6~63.6%, and the corresponding recovery rate is 52.9~45.7. %.
2) Electrolytic flotation The microbubbles are obtained by the method of electrolyzing water. The general bubble size is 0.02~0.06 mm. When used for flotation of fine cassiterite , the flotation of electrolytic hydrogen bubbles is used alone. The recovery rate of coarse selection is higher than that of conventional flotation. Significantly improved from 35.5% to 79.5%, while the grade increased by 0.8%.
In addition, research on other new processes has been carried out in recent years, such as controlling dispersion flotation, branch flotation, etc. for iron ore and black tungsten fine mud flotation, all of which have achieved good results.
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