In order for the flotation process to proceed normally, one of the necessary conditions is the dissociation of useful mineral monomers in the ore. In practice, the mineral dissociation of minerals is achieved by grinding, and the particle size of the grinding has a great relationship with the inlay size of the mineral. If the ore mill is too thick, the minerals are incompletely dissociated, and there are still a large number of continuum in the material, which has an adverse effect on the quality of the concentrate and the recovery of useful minerals. Conversely, the grinding size is too fine to make useful minerals and veins. Stone muddy, affecting the sorting effect. A daily storage box is a type of storage container that is often used to organize and store items that are used on a daily basis. Packaging Box.These boxes can come in a variety of sizes, shapes, and materials, and often have compartments or sections for different types of items.Storage Bin. They are often used in offices, homes, and schools to keep desks or workspaces tidy and organized. Some common items that might be stored in a daily storage box include stationery, makeup, jewelry, craft supplies, and small tools.Plastic Storage Bin Plastic Storage Box,Daily Storage Box,Storage Bin,Plastic Storage Bin Kunshan Muchun Electric Co., LTD , https://www.nbmuchunelectric.com
First, the impact of granularity on sorting
Flotation requires that the useful components in the ore should be dissociated from the monomers and sorted according to the floatability of the different minerals. The undissociated continuum has a floatability between the continuum and depends on the nature of the minerals exposed by the granules and the proportion and state of the different minerals. Although the size of this continuous body is suitable for flotation, the sorting effect is not ideal.
The degree of dissociation of useful minerals is measured by the degree of monomer dissociation of the mineral. Monomer dissociation refers to the percentage of beads in a new product in which the amount of a useful mineral is present in the monomer state and the ratio of the total amount of the mineral. In order to determine the degree of monomer dissociation, a representative sample may be classified by particle size by sieving, water precipitation, etc., and then the monomer dissociation degree of each mineral of each grade may be determined under a microscope.
In addition to the dissociation of minerals, the particle size of the material also has a great impact on the flotation results. The particle size is too coarse, and even if the mineral is already monomerized, it exceeds the load capacity of the bubble, and the ability is usually not easy to float. The particle size is too fine, causing muddying, and the selectivity of sorting is lowered, so that useful minerals and gangue cannot be effectively separated. Different types of mineral flotation size limit is different, according to the actual statistics of a large number of mineral processing plant, the flotation of sulfide ore particle size limit is generally for this purpose. 0.2 ~ 0.25mm; non-sulfide ores is 0.25 ~ 0.3mm; density relatively small for some non-metallic minerals, such as coal, sulfur, etc., the upper limit of the particle size is relatively large, up to 0.5mm; whereas for difficult to float oxide minerals only It reaches about 0.1mm.
The floatability of minerals is closely related to the particle size of minerals.
The figure shows the actual data on the relationship between copper , lead and zinc recovery rates and particle size in two concentrators. It can be seen from the figure that the granules of less than 10 μm or more than 100 μm have a significantly reduced floatability. Therefore, only medium-sized ore particles have the best floatability.
In order to ensure that the flotation process has a suitable particle size, it also provides a basis for the grinding classification operation, and the overflow particle size of the classification equipment must be measured every shift per day. If automatic measurement and adjustment of particle size is not available, a rapid measurement method is generally used to measure the amount of excess particle size in the overflow.
The tools used in this method are concentration pots and a sieve of 100 mesh or 200 mesh. The calculation formula is as follows:
Where in the r sieve - the yield of the product on the sieve, %;
Q1---filled pulp concentration pot weight, g;
Q2---wet sieve, the weight of the product placed on the sieve in the concentration pot after filling with water, g;
a---dry weight pot weight, g;
b --- The volume of the pot, ie the weight of the water contained in the pot, g.
The concentrating plant generally measures once every 1~2h, and judges whether the fineness and requirements are used, and changes the operating conditions of the grinding and grading cycle in time.
The loss of the coarse fraction in the tailings increases, indicating that the graded particle size is too coarse; the quality of the concentrate decreases and the loss in the tailings increases, indicating that there is excessive pulverization in the grinding.
If the mineral monomer dissociates and the particle size is basically in line with the flotation requirements, when the particle size is coarse and fine, appropriate process measures should be taken to ensure the normal selection process.
Second, the coarse particle flotation process measures
Under the condition that the mineral monomer is dissociated, when the material particle size is coarse and the flotation can be treated, coarse grinding flotation should be adopted, which can save the grinding cost and reduce the cost. However, due to the coarse grain size, on the one hand, it is not easy to be suspended in the flotation machine, which reduces the chance of collision between the ore particles and the bubbles; on the other hand, even if the ore particles collide with the bubbles, due to the large particle size, the shedding force is also Large, reducing the chance of entering the foam layer. As a result, the coarse particles are easily lost in the tailings. In the case of coarse flotation, in order to improve its floatability, the following aspects should be noted:
1. Adjust the prescription
The purpose of adjusting the prescription is to increase the fixation strength of minerals and bubbles, and to accelerate the rate of rise and fall of mineralized bubbles. It can be considered in terms of drug selection, dosage, and the like.
(1) Selection of medicaments
According to theoretical calculations, flotation of coarse particles should give the material a large contact angle. When selecting a drug, you should choose a collector with a strong ability to collect . For example, when sorting sulfide minerals, high-grade xanthate is used; when coal is selected, aromatic hydrocarbons and olefins with higher activity are selected. In addition, an auxiliary collector can be added to “consolidate†the three-phase contact perimeter to enhance the anchoring strength of minerals and bubbles. For example, in the case of flotation of fluorite and calcite , in addition to the addition of a fat hand-catching agent, a non-polar oil such as diesel oil or kerosene is added to enhance the collecting effect. When flotation molybdenum ore, in addition to the fat collector, a small amount of sulfated monoglyceride sodium salt can be added; when the coal oxide is selected, the addition of one alcohol can increase the sorting of the coarse material. effect.
(2) Reasonably increase the concentration of the drug
Studies using the rapid film method have shown that a reasonable increase in the concentration of the collector is conducive to the formation and uplift of the float. For example, with butyl sulphate flotation - 0.5mm galena, when the collector concentration is 10mg / L, the ore particles attached to the bubble, mainly - 0.25mm galena, but close to 0.5mm Rarely, almost no floating group is formed; when the concentration is increased to 50 mg/L, the coarse galena adhered to the bubble, which is close to 0.5 mm, is about 40%, and can form a floating group. In addition, when the concentration of the collector is high, the amount of mineralized bubbles floating in a unit time is 3 to 6 times larger than that at a low concentration.
2. Adjust the inflation situation
Adjust the inflation, including adjusting the volume and inflation quality.
(1) Increase the amount of inflation
The amount of aeration is very important for coarse flotation, and a larger amount of inflation is generally required. Increasing the amount of aeration can form more large bubbles, and is conducive to the formation of a collection of bubbles and ore particles, which can increase the buoyancy of the bubbles and lift the ore particles up and up. Fast film studies have shown that when flotation of 0.5 to 1 mm galena, the aeration volume is 0.5 m 3 /(m 2 ·min), which only forms a single bubble of mineralized bubbles, and the number is small, when the charge is increased to 1.5. When m 3 /(m 2 ·min), bubbles of different sizes are formed with floating clusters composed of ore particles, and the number is large. Moreover, it is also possible to increase the flotation speed, reduce the dose, and improve the processing capacity of the flotation machine.
Increasing the amount of inflation can be solved by injecting air into the flotation machine. Increased filling amount of yellow coarse iron ore flotation effect results shown below. However, excessive inflation causes the bubbles to merge, giving the opposite result.
(2) Improve the quality of inflation
The aerated mass mainly refers to the diameter of the bubble, that is, the amount of microbubbles in the slurry is increased. Both theory and practice have proved that the microbubbles formed by the precipitation of air dissolved in the pulp have good activation properties, and can preferentially precipitate on the surface of the hydrophobic mineral and form a floc group. The surface area of ​​the microbubbles is extremely large, so Coarse flotation is very meaningful.
3. Select flotation machine
When selecting the flotation machine, it should be noted that the shallow groove type flotation machine with large aeration volume and strong stirring force and capable of precipitating microbubbles is beneficial to the sorting of coarse material.
(1) Strong stirring force
In the flotation machine, the coarse material is difficult to suspend due to its large weight, which affects the collision probability with the bubble. Therefore, when the coarse-grained material is sorted, the impeller rotation speed can be appropriately increased and the slurry circulation amount in the flotation machine can be increased, that is, the suspension state of the coarse-grained material can be improved, the mineralization effect of the bubble can be enhanced, and the aeration amount can be increased, and the fineness is obviously increased. Mine recovery rate. However, the agitation intensity is too large, which adversely affects the sorting. The use of 0.4-0.6mm galena proved that the flotation machine impeller speed is lower than 2000r/min, the mineral is almost non-floating; the rotation speed is in the range of 2000～2500r/min, the recovery rate rises rapidly; when the rotation speed exceeds 2500r/min The recovery rate has dropped significantly. The high speed also reduces the quality of the concentrate. The reason is that the strong agitation destroys the floatability of the coarse material, but has little effect on the fine material, and increases the entrainment of the fine stone and reduces the selection of the sorting process. Sex, deteriorating the quality of concentrate.
(2) Select shallow groove flotation machine
When sorting coarse particles, attention should be paid to reducing the residence time of the floating particles in the tank and reducing the chance of mineral falling off. It is best to use a shallow trough type flotation machine. The amount of aeration and the effects of microbubbles have been analyzed previously.
Third, fine particle flotation process measures
The main problem with fine particles in the flotation is the poor selectivity of the sorting process. Especially when the fine mud content is relatively high, it is especially obvious. The slime in the beneficiation often refers to a fraction of less than 200 mesh, while the flotation of the flotation refers to a fine fraction of less than 18um or 10um. The sludge can be divided into two types: one for the various shale ore minerals, such as kaolin, sericite, limonite, chlorite, etc. carbonaceous page, called primary sludge; other is broken The slime formed during the process of grinding, transportation, and agitation is called secondary slime.
The quality of the slime is small, larger than the surface, and it is a thermodynamic ring stability system, which produces a series of harmful image sounds for flotation. For example, fine mud is easy to be caught in the foam, pollutes the foam product, reduces the quality of the concentrate; covers the surface of the coarse material, deteriorates the flotation effect of the coarse material, and reduces the recovery rate; the fine particle has a larger specific surface and absorbs a large amount. The flotation agent increases the consumption of students in the medicine; the increase of fine grain and slime content increases the viscosity of the pulp, reduces the aeration condition of the flotation machine, etc., which not only affects the flotation standard, but also destroys the flotation process.
For fine-grained or slime content, effective process measures should be taken to reduce the harmful effects of slime.
1. Adjust the prescription
(1) Selection of medicaments
Fine-grain sorting should pay attention to the selection of surnames in the process. When selecting a drug, a selective agent should be selected. Separation of sulfide ore should be selected as black medicine and low-grade xanthate. These collections have better selectivity; linear hydrocarbons are used for coal preparation. The choice of foaming agent should be selected from fatty alcohols or ethers. The foam formed by these agents is brittle and has a large water content, which is beneficial to the secondary enrichment to improve the quality of the concentrate.
(2) Dosing method
Sub-dosing and dosing should be used to keep the pesticide at the lowest reasonable ability in the pulp at any time. One dose of the drug allows a large amount of the drug to be adsorbed on the slime, reducing the selectivity of the agent and increasing the consumption of the agent.
(3) Adding slime dispersant
Disperse the slime to eliminate the coverage of the slime on other materials and affect the sorting of these materials. Sludge dispersants commonly used water glass, sodium carbonate, sodium hexametaphosphate, sodium phosphate and the like.
2. Operating factors
(1) Concentration adjustment
Usually, the concentration of the slurry is relatively rare. On the one hand, the slime can be prevented from contaminating the concentrate foam; on the other hand, the viscosity of the slurry is lowered and the selectivity of the sorting process is improved.
(2) Spray washing foam products
Appropriate spraying of clean water and washing concentrate on concentrate foam products can strengthen secondary enrichment, reduce fine mud pollution and improve concentrate quality.
3. Pre-de-sludge
Desliming is a method to remove the influence of slime, and the cyclone is used for classification to achieve the purpose of de-sludge. For example, a cyclone is used to divide the material into two fractions before flotation, and the fine mud is treated according to its quality, and the fine fraction and the coarse fraction are separately treated. If the slime can be floated with good sex, a small amount of foaming agent can be added before the flotation, and the slime is removed first to achieve the purpose of deliming. When the nature of the suspended minerals and the slime is quite different, the prescription for removing the slime can be specially formulated for deliming. For example, a copper oxide ore containing a large amount of limonite mud, first using oxidized paraffin soap as a collector, floating the limonite ore, and then flotation of copper oxide, so that the sub-indicators are improved.
4. Other fine particle sorting methods
As the mining of industrial deposits is poor, fine, complicated and difficult to develop, the fine materials need to be recycled. Since the 1960s, many new processes for processing fine particles have been developed. Some of these are used in actual industrial production.
(1) Selective flocculation
The flocculant is used as a component in the floe ore, while the other components are still in a dispersed state, thereby separating the useful mineral from the gangue. The Tierden Concentrator used this method to select fine-grained hematite. This method can also be used selected from bauxite, kaolin, apatite, pyrite, sphalerite. The United States, Germany, the United States, the Soviet Union and other countries have used this method to study the election, but still in the laboratory stage, there is no example of industrial application.
(2) Carrier flotation
The essence of carrier flotation is to use an auxiliary material as a carrier. After adding the flotation agent, the fine particles to be sorted are covered on the carrier, and then the fine particles are floated with the carrier by froth flotation. The carrier can be used with the same kind of apatite; heterogeneous minerals can also be used, and the carrier particle size is the same as the general flotation particle size. For example, as a carrier selected from the fine pyrite gold; with calcite as a carrier, anatase impurities floated kaolin. Carrier flotation can also be used in addition to the capture method. For example, when molybdenum and zinc are separated, the coarse intragranular zinc ore which is treated by the ground can be inhibited to promote the inhibition of the zinc ore in the fine particles.
(3) Reunion flotation
Reunion flotation, also known as milk selection or oil group flotation. The fine-grained mineral or natural hydrophobic fine-grained mineral treated by the collector forms a mineral-like oily foam or oil film by the action of neutral hydrocarbon oil and stirring force, and is recovered by froth flotation or screening. This method has been used for the sorting of fine manganese ore, ilmenite, apatite. There are two types of operation processes: one is to add the emulsion and the neutral oil to prepare the emulsion; the other is to add the neutral oil and the collection in the high-concentration slurry with the solid content of 70%. Agent, stir vigorously, control the time, and then scrape off the upper layer of foam.
(4) Shear flocculation
The fine-grained minerals treated by the collector are stirred under agitation for a long period of time, and the hydrophobic particles collide with each other under high turbulence. Under the action of high shear force, the hydrated membrane gradually changes. The thin, hydrophobic particles are flocculated with each other and then sorted by conventional methods. Because of the strong effect, the dosage of the drug is greatly reduced. The method has been successfully used to sort scheelite and is considered a promising new process.
(5) Microbubble flotation
Early microbubble flotation was a vacuum flotation method that precipitated microbubbles from solution. Flotation-0.01mm barite , fluorite, quartz and other tests have proved that it is an effective method to precipitate microbubble flotation fine particles from water. When the other conditions are the same, with the conventional flotation, the grade of the barite concentrate is 54.4%, and the recovery rate is 30.6%. With vacuum flotation, the grade can be increased to 53.6 to 63.6%, and the corresponding recovery rate is 52.9 to 45.7. %.
In 1971, Sebba invented a method of dispersing microbubbles in a surface active solution for sorting ultrafine-grained slime. Yon et al. further tested the coal slurry of less than 100 mesh in the Eagle mine in the United States. Under the conditions of substantially the same recovery rate, the conventional flotation of the clean coal ash was almost twice as high as that of the microbubble flotation. In general, the recovery rate is slightly higher and the ash content is slightly lower. The stability of the foam has a great impact on the sorting.
Others have also carried out research on various new processes such as electrolytic flotation, electric field flotation, and electromagnetic flotation treatment of pulp to solve the problem of fine particle sorting.
     In order to obtain satisfactory flotation results during the flotation process, a series of process factors affecting flotation must be mastered and controlled. For example: particle size, flotation reagent system, pulp properties, flotation process and structure, etc. According to different mineral properties, different flotation process conditions are formulated to stabilize the flotation process and obtain the best indicators.