How to distinguish the quality of the foaming agent

A foaming agent refers to a class of surfactants that reduce the external tension of water to form a foam, such that air bubbles in the aerated flotation slurry can adhere to selectively floating mineral particles. The molecular structure of the foaming agent is similar to that of the collector, and most of them are heteropolar molecular surface active materials composed of polar and non-polar groups. One end of the molecule is a polar group and the other end is a non-polar group. The polar group of the collector is pro-solid (mineral), non-polar based air. The polar group of the foaming agent is hydrophilic, and the non-polar group is air-friendly. Oriented at the water-air interface to reduce the external tension of the water, so there is foaming.

1. The action of the foaming agent avoids the merger of bubbles, so that the bubbles dispersed in the slurry have a smaller diameter and a certain life.

2. Increase the mechanical strength of the bubble to reduce the movement speed of the bubble and increase the residence time of the bubble in the slurry. Ordinary foaming agents have the following common properties

(1) The molecular structure of the coal washing agent is usually an isopolar organic substance, one end is a polar group, and the other end is a non-polar group; the polar group is hydrophilic, and the non-polar group is hydrophilic, so that the foaming agent can be made The molecules create an alignment at the interface between air and water.

(2) The foaming agent is an external active substance which can reduce the external tension of water. The term "surface activity" as used herein refers to a decrease in the surface tension caused by an increase in the concentration of the unit foaming agent in the solution. Generally speaking, the apparent activity of the same series of organic surfactants is increased by "one-third" (also called "Trubey law"), and the solubility is added in the same manner. In the case of alcohols, for example, from ethanol, any alcohol has a surface activity that is three times that of its nearest lower alcohol and one third of its nearest higher alcohol. The solubility is gradually reduced by the same law.

Ordinary collectors have a medium solubility of 0.2 to 5 grams per liter. As described above, the apparent activity in the homologue increases as the molecular weight increases, but at the same time the solubility decreases as the molecular weight increases. Flotation theory proves that due to the effect of these two factors, the common foaming agent has a carbon number of 5 to 11 in the molecule.

There are four basic ways to determine the foaming performance of a foaming agent aqueous solution:

(1) Agitate the foaming agent aqueous solution by hand or mechanically for several minutes, and then measure the volume of the foam layer.

(2) Stir in a foaming agent aqueous solution with a rotating agitator or a porous disk moving up and down, and then measure the volume of the foam.

(3) In a glass tube with a sand core hole bottom plate, a small bubble of air or other gas is bubbled into the aqueous solution to be tested, and then the foam height is measured.

(4) Drop the aqueous foaming agent from a certain height, and then stop measuring the above four basic methods for the foam produced, either by measuring the height of the foam generated within a certain period of time, or measuring the liquid contained in the foam layer. weight.