Foaming agent is a kind of surfactant that can reduce the external tension of water and form a foam, so that the air bubbles in the air flotation slurry can be attached to the mineral particles floating on the flotation. The molecular structure of the foaming agent is similar to that of the collector, most of which are heteropolar molecules composed of polar and nonpolar groups. One end of the molecule is a polar group and the other is a nonpolar group. The collector has a polar group which is close to solid (mineral) and a nonpolar group which is close to air. The polar group of the foaming agent is hydrophilic, and the nonpolar group is air friendly. It is arranged in the direction of the water air interface to reduce the external tension of water, so it has the effect of foaming. 1. The function of the foaming agent is to avoid bubble merging, so that the bubbles dispersed in the pulp have a smaller diameter and a certain life. 2. Increasing the mechanical strength of bubbles reduces the movement speed of bubbles and increases the residence time of bubbles in pulp. Common foaming agents have the following common properties (1) The molecular structure of coal washing agent is usually heteropolar organic matter, one end is polar group, the other end is nonpolar group; the polar group is hydrophilic, nonpolar group is hydrophilic, so that the molecules of foaming agent can produce directional arrangement at the interface of air and water. (2) Foaming agent is a kind of surface active substance, which can reduce the surface tension of water. The so-called apparent activity refers to the reduction of the apparent tension caused by the increase of the concentration of the unit foaming agent in the solution. Generally speaking, for the same series of organic surfactants, their apparent activity increases according to “one third probability” (also known as “truebe law”), and their solubility increases according to the same law. Take alcohols as an example. Starting from ethanol, the apparent activity of any alcohol is three times that of its nearest lower alcohol and one third of its nearest higher alcohol. However, the solubility decreases gradually according to the same rule. Ordinary collectors require a medium solubility of 0.2-5g/l. As mentioned above, in homologues, the apparent activity increases with the increase of molecular weight, while the solubility decreases with the increase of molecular weight. Flotation theory proves that due to the effect of these two factors, the number of carbon atoms in the molecule of common foaming agent is generally 5-11, which is more suitable. There are four basic methods to determine the foaming performance of foaming agent aqueous solution: (1) stirring the bubbling solution for several minutes by hand or mechanical means, and then measuring the volume of the foam layer. (2) stirring with a rotating agitator or a moving multi hole tray, and then measuring the volume of the foam. (3) in a glass tube with a sand core, a small bubble of air or other gases is pumped into the tested aqueous solution, and then the height of the foam is measured. (4) drop the foam solution from a certain height, and then stop measuring the above four basic methods. All of them are measured at a certain time or the height of the foam produced, or the weight of the liquid contained in the foam layer.
Post time: Feb-07-2020