Float gas phase and its properties

The bubbles formed by air during froth flotation are an alternative vehicle. Some floating mineral slurry particles can adhere to the bubbles float, can not adhere to the remaining air bubbles remaining in the pulp, so that they are separated. After the surface of the ore particle adheres to the bubble, its floatability changes. The bubbles can also be precipitated from the solution due to pressure drop and preferentially adsorbed onto the hydrophobic surface of the mineral to promote adhesion of the ore particles to the large bubbles. The gas phase must form a sufficient amount of gas bubbles in the solution to ensure that the floating mineral has sufficient bubble area for it to adhere. The particle size of the bubble should be compatible with the particle size of the flotation mineral, and there is a certain amount of microbubbles which are precipitated after the air is dissolved, so as to ensure the best flotation effect. The gas phase of the flotation is mainly air, and the air is mainly a mixture of oxygen, nitrogen, carbon dioxide and the like. The different components of the air have different solubility in water, and thus have different effects on minerals and water, and have different effects on sorting.

1. The nature of air and its impact on sorting

Air is a typical non-polar substance with a symmetrical structure. It is easy to combine with non-polar surfaces, and it can preferentially adhere to non-polar hydrophobic surfaces during sorting.

Oxygen in the air is a flotation promoter for sulfide ore. Tests have shown that the non-oxidized, non-oxidized sulfide ore surface is hydrophilic and cannot be directly floated. After adsorption of oxygen on the surface of the sulfide ore, the surface hydration of the mineral is weakened, and the xanthate anion collector is more easily adsorbed and fixed on the surface of the mineral. When the xanthate anion and oxygen are present in the slurry, the oxygen is first adsorbed, and then the xanthate anion is adsorbed. Contact angle measurements indicate that oxygen increases the contact angle of the mineral surface, while nitrogen and carbon dioxide do not. Determination of the sulfide ore, the contact angle of the non-sulfide ore and coal show the same results will be, indicating that the presence of oxygen flotation Advantageously, especially when used in particular xanthate flotation of sulfide ore. Therefore, when separating many non-sulfurized ores, oxygen can be used as an activator and nitrogen as an inhibitor to promote mineral separation by changing the ratio of oxygen to nitrogen in the slurry. But should pay attention to:

1 The amount of oxygen required for different minerals at the time of sorting is different. When the optimum value is exceeded, it will inhibit. At the same time, if the oxygen content is too high, it will promote the oxidation of the mineral surface and reduce the hydrophobicity of the mineral surface, which is not good for flotation.

The role of oxygen in the process of sorting is different from the role of oxygen in the transportation and storage of minerals. The former refers to the flotation of certain minerals activated by oxygen dissolved in the slurry during the sorting process. The latter only oxidizes minerals, turns sulphide ore into oxidized ore, coal into oxidized coal, and increases the hydrophilicity of the mineral surface, making the flotation process difficult. Therefore, the different roles of oxygen in these two processes should be strictly distinguished.

2. The dissolution of air in the slurry

The solubility of various components in the air in the slurry is different. The solubility of each component is related to the partial pressure of the component, the temperature, and the concentration of other substances dissolved in the water: the solubility of air in water decreases as the concentration of other substances dissolved in the water increases; as the partial pressure increases, the solubility increases. Many new flotation machines take advantage of this feature. For example, the jet flotation machine pressurizes the slurry containing a large amount of gas, and when the nozzle is ejected from the nozzle, the flotation effect is enhanced by the microbubbles generated when the dissolved gas is supersaturated and precipitated.

3 Coal oxidation and floatability changes

Coal is easily oxidized, and the surface of the oxidized surface is floatable, which affects the floating. The oxidation of coal is oxidized by the side chain of benzene nucleus or benzene nucleus to form functional groups such as phenol group, carbonyl group and sulfhydryl group, thereby increasing the number of oxygen-containing functional groups of coal and increasing its hydrophilicity. Generally, oxygen, nitrogen and sulfur functional groups on aromatic hydrocarbons promote coal oxidation, while aromatic hydrocarbons that lose side chains are most difficult to oxidize. Therefore, the presence or absence of functional groups on the surface of coal is the main factor determining whether coal can be oxidized. If the number of functional groups is continuously increased during the oxidation process, the oxidation process is faster and proceeds from the surface to the inside. It is worth noting that the oxidation of coal slime in water is longer than in air, which is due to the hydrogen bonding of water and oxygen-containing functional groups, which intensifies the oxidation of coal. Therefore, in the flotation of coal slime and the treatment of slime water, it is necessary to avoid the excessive time of the slime in the water, thus affecting its floatability.

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