In the slurry, the foaming agent molecules are adsorbed at an air-liquid interface in an irregular orientation, and the non-polar groups are directed toward the air, that is, toward the inside of the bubble. The polar group faces the water and attracts water molecules (the polar ends are hydrated). Therefore, the foaming agent molecules can reduce the flow velocity and evaporation speed of the water layer between the cells, thus preventing the cracking of the cell walls. After the foaming agent molecules are aligned on the surface of the bubble, when the two bubbles contact and collide, two layers of foaming agent molecules and a hydration layer of their polar groups are interposed in the middle, so that the bubbles are difficult to merge, and the small bubbles are easily preserved. Small bubbles are more resistant to external vibrations than large bubbles, and their stability is stronger. Another major reason for the foaming agent to stabilize the bubble is that the foaming agent imparts elasticity to the surface of the bubble, as does a flexible rubber film. When the bubble is subjected to vibration or is subjected to an external force, the bubble suddenly deforms. If there is no foaming agent molecule on the surface of the bubble, the wall of the bubble is thinned to cause cracking. However, when there are foaming agent molecules on the surface of the bubble, the orientation of the foaming agent molecules reduces the surface tension, and when the bubble is deformed by an external force, the interface of the bubble wall also increases, causing the concentration of the bubble layer on the surface of the bubble to decrease, such as Figure 6-22 shows. The surface tension of the gas-liquid interface is significantly increased. On the one hand, the increase of the surface tension is beneficial to restrain the gas molecules in the bubble from rushing outward, and on the other hand, the bubble generates a large contraction force, which overcomes the bubble generation. Cracked external force. The size of the bubbles due to the adsorption of the foamer molecules depends on the activity, solubility and concentration of the foaming agent molecules. When the concentration of the solution and the concentration of the gas-liquid interface are unbalanced due to the expansion of the interface, the adsorption of the molecules from the solution to the interface is too fast or too slow, and the elasticity of the bubbles is weakened. Therefore, it is necessary to use a foaming agent having an appropriate activity and solubility, and the amount thereof is appropriately controlled. From the above, it is known that the action of the foaming agent contributes to the formation of bubbles and enhances the stability of the foam. In the flotation beneficiation process, since the mineral particles attached to air bubbles, the bubbles formed bubble mineralization. The three-phase foam formed by the mineralization of the two-phase foam is more stable. This is because the mineral particles have the following effects on the bubbles: 1 can reduce the flow velocity of the water layer in the foam, because the mineral particles adsorb on the bubbles to form a capillary tube for water absorption; 2 The ore particles are adsorbed on the bubble wall, which hinders the mutual merger of the bubbles; 3 The collector interaction on the surface of the ore particles can increase the mechanical strength of the bubbles. In addition, the stability of the foam is also related to other factors. In general, the content of the slime will also make the foam more stable. In addition, the pH value of the pulp, soluble salt content, etc. also have an effect on the stability of the foam. The commonly used foaming agents are shown in Table 6-5. Etherol and phenylethyl ester oils are novel foaming agents used in recent years. In addition, it is also a widely used foaming agent for foreign countries, such as glyceryl oil, neosinol oil and butyl ether oil methylpentanol. Filter Housing,Water Filter Housing,Housing Filter,Bag Filter Housing ANPING HANKE FILTER TECHNOLOGY CO , https://www.anpinghankefilter.com
Flotation - the mechanism of action of foaming agent and common foaming agent
Commonly used foaming agents are heteropolar surface active substances. One end of the molecule is a non-polar hydrocarbon group, and the other end is a hydrophilic group with strong hydrophilicity, as shown in Figure 6-21.