The basic principle of special flotation (4)

(IV) Analysis of special flotation dynamics Some scholars have conducted some research on the ion flotation kinetics, but it is still to be further studied. Only one of them is introduced here.
According to the research, the speed of ion flotation has nothing to do with its mechanism, and can be expressed by the following formula:

Where C—the concentration of the target component;
t———flotation time;
Q———the amount of bubbles;
V—the volume of liquid in the flotation cell;
K———The dimensionless kinetic coefficient.
In general, k is a complex function of c, and the average value k ^{- of the} kinetic coefficients in the time range from 0 to t is obtained by:

Where ε - the recovery of the target component.
Under the condition of special flotation, the recovery rate ε is industrially significant within the range of 90 to 99%. Under this condition, the flotation time required to achieve a given recovery rate can be calculated according to equation (13). Or calculate the k value under various process conditions, and analyze the kinetic conditions of the process with the best value of k as the target.
The kinetic coefficient k is the equilibrium state of the target component on the bubble 10,000 k ₁ (adsorption or adhesion), the kinetic factor k ₂ liquid and the foam layer height k ₃ (the completeness of the separation), the specific surface area of ​​the bubble k The product of the kinetic coefficients of _4, etc. K=K ₁ •K ₂ •K ₃ •K ₄ (14)

K ₂ and k ₃ vary from 0 to 1; As the average diameter of the bubble); as for the k ₁ , in view of the complexity of the problem, it is not currently possible to write a formula for the adsorption or precipitation of the ionic surfactant on the surface of the floating bubble on the surface of the floating bubble, but it can be calculated It corresponds to the limit single layer value (k ₁ ) _m of the particles adsorbed or adhered to the surface of the bubble. For adsorption during ion flotation: [next]

In the case of hydrophobic precipitate flotation (adhesion flotation),

For the equations (15) and (16), the measure of ( k ₁ ) _m is "cm" and the measure of C is "mol/liter".
Under the conditions of industrial mechanical agitated flotation machine and aerated mechanical agitated flotation machine, the kinetic coefficients of different mechanisms of K ₂ = K ₃ =1, d ^- =1 mm and k ₄ = 60 cm ^-1 are respectively :
Adhesion mechanism (k ₁ ) _m =6(10-5~1)/C (17)
Adsorption mechanism k _m =6(10 ^-6 ～10 ^-5 )/C (18)
The range of (K1) M values ​​for the corresponding two flotation processes is shown in Figure (5). Analysis of these data leads to two conclusions:

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(1) According to the kinetic conditions, the adhesion flotation mechanism is more ideal than the adsorption flotation mechanism.
(2) Adsorption mechanism The practical k value can be guaranteed only under the condition of concentration less than 3×(10 ^-4 ～10 ^-5 ) mol/L.
The range 3 in the above figure (5) is the k value calculated according to the experimental results of the flotation speed and other flotation indexes according to the equation (12). This shows that:
(1) When the original concentration of the target component is in the range of 10 ^-5 to 10 ^-2 mol/liter, that is, in the effective concentration range of ion flotation, the adhesion mechanism is better than the adsorption mechanism according to the kinetic conditions.
(2) Kinetics of adhesion mechanism when the original concentration of the target component is 10 ^-5 to 10 ^-2 mol / liter under the aeration condition of a conventional mechanical agitation flotation machine and a pneumatic mechanical agitation flotation machine The coefficient average k is in the range of 1 to 20. This corresponds to a flotation time of only a few minutes when the recovery is 90 to 99%.
From the kinetic analysis, the adhesion mechanism of special flotation has greater industrial significance.

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