1. Hydration: Orientation of water molecules to form a hydration layer. 5. The effect of hydration on the floatability: 2. Solid-liquid interface charge (electrical cause) Shaft Assembly,Customized Shaft,Input Shaft,Output Shaft,Counter Shaft ShaoXing Change Auto Synchronizer Ring Co.,Ltd , https://www.sxcjautoparts.com
Ionic hydration: the directional arrangement of water molecules on the ionic surface.
Hydration of mineral surfaces: the orientation of water molecules on the mineral surface.
2. Principle of hydration:
(1) Properties of unsaturated bonds on mineral surfaces: ions, covalent, molecular bonds.
(2) The bond energy of the unsaturated surface of the mineral surface: the polarity of the mineral surface.
(3) The surface of the polar mineral has strong hydration, the hydration layer is thick, and the water molecules are closely arranged;
The surface of non-polar minerals is weak in hydration, the hydration layer is thin, and the water molecules are sparsely arranged.
3. Structure of the hydration layer:
Diffusion structure: The degree of orientation of water molecules in the hydration layer gradually decreases as the distance from the mineral surface increases.
The hydration layer is a transitional zone between the mineral surface and normal water, similar to the continuation of a solid surface.
4. Properties of the hydration layer:
(1) The viscosity is larger than ordinary water;
(2) high stability;
(3) has a certain amount of energy;
(4) The solubility is lowered. 
(1) Hydration is consistent with the wettability of the mineral surface, as opposed to buoyancy.
(2) The hydration of the mineral surface depends not only on the characteristics of the surface of the mineral surface itself, but also on the nature of the molecules or ions adsorbed on the surface of the mineral.
Second, the interface electrical phenomenon 1. The charge of the liquid-gas interface The surface of the liquid-gas interface adsorbs the surface active ions, so that the positive and negative concentrations of the adsorption at the liquid-gas interface are different, thus carrying the charge, and most of them are negatively charged.
In the flotation process, the adsorption of surface active ions at the gas-liquid interface is the most common phenomenon. example:
(1) Selective adsorption of ions:
The new synergy between the mineral surface and water on different ions causes the mineral surface to adsorb unequal amounts of positive and negative ions in the electrolyte solution, which promotes the charging of the mineral surface.
A. In the solution, the amount of positive and negative ions, excess ions are easily adsorbed.
B. The electrical properties of the mineral surface itself are easy to adsorb.
C. The hydration of positive and negative ions is different, and the tendency to be adsorbed is different.
(2) Selective dissociation of mineral surface components:
A. The positive and negative ions that make up a solid often have different solvency in the medium.
B. After some minerals and water, new substances are formed at the interface of the two phases, and the interface electrical properties are closely related to the new products produced.
For example: Quartz is negatively charged.
Lattice rupture:
Hydrolysis produces silicic acid-like products:
Dissociation negatively charged:
(3) Mineral lattice defects Due to mineral rupture, lack of certain ions, or non-equal substitution of the same type of image, it also promotes the imbalance of the charge on the surface of the mineral, which in turn charges the surface of the mineral.
Third, the double electric layer 1. The structure of the double electron layer After the mineral surface is charged in the solution, due to the action of the electrostatic force, the opposite water is absorbed in the aqueous solution, and an electric double layer is formed on the mineral surface.
The evolution history of the model:
(1) Model electric double layer plate: Stability of ion stressed environment, considered plate capacitors, or applied to a high concentration of metal salts.
(2) Diffusion electric double layer model: excessive emphasis on the mobility of ions, divided into inner layer and diffusion layer.
(3) Electronic layer model (Stern): inner layer, Stern layer, diffusion layer.
2. Double electron horizon (1) Total surface potential ψ0.
The potential of the charged surface is the total potential difference between the mineral surface and the solution. For conductors or semiconductor minerals, the electrode can be made to measure ψ0.
Non-conducting minerals can be calculated using the activity of the positioned ions in the solution.
General oxide, with H+ or OH- ions as the localization ion, n=1, the total potential of the oxidized mineral surface:
(2) Motorized potential ξ--Zete potential and Stern potential ψδ.
The potential on the sliding surface and the potential difference inside the solution are called the zeta potential.
The potential difference between the Stern interface and the solution is called the Stern potential. The motor potential has great practical significance in the theory of flotation.
3. Zero point and isoelectric point (1) Zero point PZC or ZPC:
The negative logarithm of the concentration of the ion in the solution when the static charge on the surface of the mineral is zero. If the positioning ion is H+ or OH-, the pH value at ψ0=0 is zero electric point.
(2) The isoelectric point PZr or IEP:
The negative logarithmic value of the electrolyte concentration in the solution when the motor potential is zero. Or the pH of the solution. PZr is related to the pH of the solution and also to the concentration of ions that produce the characteristic adsorption. In the system, when the characteristic adsorption is not used, ξ=0, the charge density is also zero, PZC=PZr.
4. Influencing factors and potential curves of the electric double layer 1) Influencing factors of the electric double layer (1) Characteristic adsorption of impurity elements:
Impurity elements: mainly refers to inorganic salts, which mainly affect the zeta potential.
law:
A. The higher the valence of the cation, the more obvious the decrease in the motor potential.
B. The price is the same, the larger the volume, the more obvious the impact.
C. In most cases, the cation can increase the zero point; the anion can reduce the zero point.
D. Organic polar molecules can make PZC drift, its properties determine the drift direction, and the concentration determines the drift size.
(2) The effect of temperature:
Most minerals can decrease PZC with increasing temperature.
(3) The effect of solid content increases with increasing temperature.
2) Potential curve:
The relationship between the potential in the electric double layer and the distance of the mineral surface.
(1) The inner layer is positioned to adsorb ions, changing ψ0 and ξ.
(2) Ion adsorption in the solution, changing the enthalpy, does not change ψ0.
(3) Excessive adsorption of anti-ion ions, changing ψ0 and ξ, ψ0 is opposite to ξ symbol.
(4) When the positioning ion is H+ or OH-, the pH value of the solution changes while changing ψ0 and ξ.
5. Interface electrical properties and mineral floatability (1) The relationship between mineral surface properties and wettability.
When the zero point is PZC, the contact angle is the largest, the surface of the mineral is charged, θ becomes smaller, the wettability becomes better, and the floatability deteriorates.
(2) Effect of electric double layer and motor potential on flotation (zero electric point electric potential and mineral flotation effect)
A. The effect of the electric double layer on the physical adsorption of the agent on the mineral surface:
Physical adsorption is electrostatic adsorption.
B. Effect of double layer of mineral surface on flocculation and dispersion of mineral suspension:
Reduce and compress the potential to flocculate the mineral suspension - instability.
Raise and expand the electric double layer to make the mineral suspension dispersed--stable.
C. The effect of double electric layer on the coverage of fine mud on the ore particles:
The fine mud is usually negatively charged, and the ore particles are positively charged, that is, they can be covered.
D. Relationship between motor potential and flotation activity:
As the mineral electric potential decreases, the floatability of the mineral increases, and the flotation effect becomes better. The forward motorized potential difference is used to evaluate the change in mineral flotation activity. The larger the coma, the better the effect of the agent and the greater the increase in flotation activity.
1. Hydration of mineral surfaces