First, the foam layer Transmission Synchronizer Assembly Gear Synchronizer,Transmission Synchronizer,Automobile Synchronizer,Customized Synchronizer ShaoXing Change Auto Synchronizer Ring Co.,Ltd , https://www.sxcjautoparts.com
The foam layer is related to the nature of the ore, the type of flotation machine, and the pharmaceutical system. When the flotation machine has a large amount of aeration and a reasonable pharmaceutical system, a large number of foams with suitable stability can be formed to form a thick foam layer. For stable operation, the foam layer should be kept to a certain thickness. The thickness of the foam layer can be adjusted by controlling the slurry level. Generally, a thicker foam layer can improve the concentrate grade, and a too thin foam layer will deteriorate the quality of the concentrate. This is due to the foam layer foam, the upper layer is continuously broken, the water flow of the water film returns to the flotation machine slurry after the bubble bursts, the hydrophobic mineral remains on the surface of the foam layer, and the gangue particles also return to the slurry with the water flow, and the thick foam layer It is conducive to the progress of secondary enrichment, which is conducive to the improvement of concentrate quality; the foam layer is too thin, there is no secondary enrichment, and the unmineralized particles are often brought into the concentrate, which affects the quality of the concentrate.
Spraying water onto the foam layer enhances the secondary enrichment. In the stellite ore flotation, the foam layer is sprayed with water to wash, and the fine-grained slime is washed away to improve the quality of the concentrate. The enrichment ratio is increased from an average of 22.12 to 50.88. In addition, when rinsing, the diameter of the surface layer bubble is reduced, and the total surface area of ​​the bubble is increased, which is favorable for the recovery of the coarse material and the recovery rate. As a result, in the same concentrate quality, such as rinsing, the number of selections can be reduced, and the amount of medication can be saved.
Generally, in the case of sweeping and rough selection, in order to improve the recovery rate, a thinner foam layer can be used, and in order to ensure the quality of the concentrate, a thicker foam layer should be used.
Second, the quality of foam
Foam quality refers to the bubble diameter composition and the number of microbubbles.
Bubble diameter
The size and composition of the bubble have a direct impact on the flotation results. The diameter of the bubble should not be too large. When the amount of inflation is constant, the diameter of the bubble is too large, which will reduce the total surface area of ​​the bubble, which is not conducive to the collision of the useful mineral. The foaming agent is added to reduce the diameter of the bubble. The bubble is reduced, and the larger the surface area is, it is favorable to form a mineralized foam, but the buoyancy of carrying the ore particles is small. Therefore, in order to ensure that the mineralized bubbles have sufficient buoyancy and a certain floating speed, the bubbles should have a certain diameter composition, and have bubbles of different sizes and proportions.
The diameter of the bubble is related to the particle size of the flotation material. To ensure that the bubbles with the ore particles can rise in the slurry, the minimum diameter of the bubble should be:
Where Dmin is the smallest diameter of the bubble, cm;
D---mineral diameter, cm;
Δm---the density of the ore particles, g/cm 3 ;
Δp---the density of the pulp, g/cm 3 ;
The bubble diameter can be controlled by the amount of aeration and the type and amount of foaming agent selected.
2. Microbubbles
In order to improve the flotation effect, especially the coarse-grained flotation, there should be a certain amount of microbubbles in the bubbles, which is favorable for forming the floc cluster and improving the recovery rate of the coarse fraction. As mentioned above, the gas dissolved in the slurry will precipitate out of the solution as the pressure decreases, forming microbubbles. This microbubble is selective and therefore preferentially precipitates on the surface of the hydrophobic mineral. The mineral surface with microbubbles is easy to adhere to large bubbles, forming a floc composed of large and small bubbles and ore particles, which is advantageous for coarse flotation.
Microbubbles can be formed by:
(1) The aeration amount of the agitation flotation machine increases the negative pressure in the slurry, which contributes to the precipitation of the microbubbles. The amount of air released under different vacuum degrees was measured for vacuum flotation. The results are shown in the figure:
As the degree of vacuum increases, the amount of microbubbles precipitated from the solution increases, so it is advantageous to increase the negative pressure in the flotation machine for the precipitation of microbubbles. Others such as slurry agitation strength, slurry concentration, and the circulation of the slurry in the vertical direction of the machine have a certain influence on the amount of microbubble precipitation.
(2) Use different aerators. Such as jet, cyclone and vacuum decompression flotation machines, these flotation machines are given a certain pressure due to the different forms of the inflator, the pressure in the flotation machine is drastically reduced or due to vacuum pumping, floating A high negative pressure is generated in the machine to promote the precipitation of microbubbles.
(3) Electrolytic foaming. Electrolytic foaming relies on an external electric field to make the flotation medium, water electrolysis, generate microbubbles of oxygen on the anode; microbubbles which generate hydrogen on the cathode, and the electrolysis process is as follows:
The particle size of the microbubbles produced by electrolysis is extremely small. When the current intensity is 100-400 A/m 2 , the particle size of the hydrogen microbubbles is 15-20 μm, and the particle size of the oxygen microbubbles is 45-60 μm. The size of the bubbles can be passed through the electrolysis current. The electrode material, the geometry of the electrode, and the pH of the medium are controlled. In addition to the generation of microbubbles, the electrolysis gas itself is an active regulator. They are in an atomic state when they are deposited from the surface of the electrode. Although the time is short, it can have a significant effect on the mineral surface and the flotation agent, sometimes it can be greatly Improve selectivity. For example, electrolysis of oxygen can lower the pH of the slurry from 7.2 to 4.95; hydrogen can increase the pH from 7.2 to 11.45. Oxygen can improve the flotation of sulfide ores activity mineral brass, pyrite and the like; cassiterite flotation for hydrogen activation, but that the sulfide ore flotation of quartz and deterioration. Therefore, for different minerals, different types of electrolytic gas generators should be selected.
There are more than ten types of electrolyzed gas generators, which are classified into three types:
(1) generating a mixed gas of hydrogen and oxygen for sorting;
(2) using only the hydrogen produced;
(3) Use only the oxygen produced.
The effect of flotation foam on flotation
     The flotation process is carried out in three phases of solid-gas liquid. The amount of foam, the stability of the foam layer, the thickness of the foam layer, the size of the bubble, and the bubble structure are all directly affecting the flotation index.