The interface phenomena occurring during the flotation process are very complicated. In addition to physical adsorption, wetting, adsorption, and electrical phenomena, various chemical adsorptions and chemical reactions occur on the surface of the ore and inside the slurry. How to distinguish between chemical reaction and chemical adsorption? Since the chemical reaction between the solid and the liquid starts from the surface of the ore particle, it can be considered that the surface adsorption is a prerequisite for the chemical reaction, and the chemical reaction is the continuation of the chemical adsorption, but the chemical adsorption and the chemical reaction are all chemical bonds. Chemical adsorption occurs when the concentration of the agent is low, and no new compounds are formed after adsorption, and the original lattice of the solid phase is not destroyed. The chemical reaction generally occurs when the concentration of the drug is high, and often destroys the original crystal lattice on the surface of the solid phase, resulting in the phenomenon of lattice lattice rearrangement.
S 2- sulfide ion, such as chemical reactions occurring in the surface of the white lead ore:
Interface interface PbCO 3 ]PbCO 3 +S 2- → PbCO 3 ]PbS↓+CO 2 2-
Internal surface internal surface (after reaction)
The film of PbS formed on the surface of the white lead ore is due to the fact that the product of the concentration of S 2- and the concentration of Pb 2+ is greater than the solubility product of PbS in water. During the reaction, the surface compound of PbS which started to be formed was extremely thin, and then CO 3 2- in the crystal lattice near the surface of the white lead ore continued to be replaced by S 2- , and a PbS film having a certain thickness was gradually formed. At this point, the crystal lattice of the white lead ore is destroyed, resulting in a new lattice of lead sulfide.
Of course, the form of the agent acting on the surface of the mineral is many, and under different conditions, it has different forms of action. For example, the effect of oleic acid and iron minerals, if the concentration of the agent is low, when the pH value is favorable for the dissociation of the agent into ions, single particle adsorption occurs, otherwise molecular adsorption occurs. When the concentration of the drug is high, half-micelle adsorption occurs. Due to the non-uniformity of the surface of the ore particles, the residual bond strength at different parts of the surface is also greatly different. Chemical adsorption generally occurs in chemically active active centers, and therefore, the adsorption of the agent on the mineral surface tends to be uneven.
The role of the agent on the surface of the ore particles often has different names. For example, the adsorption of xanthate anions on the surface of galena can be called chemisorption, ion adsorption or single layer adsorption, sometimes called chemical reaction.
In some cases, only chemical adsorption can occur, and chemical reactions cannot be performed. For example, by placing barium sulphate in a dilute sodium laurate solution, since barium laurate is more soluble than barium sulfate, it is virtually impossible to carry out a chemical reaction to form barium laurate, but lauric acid is adsorbed in a chemically adsorbed form. The surface of barium sulfate.
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