Chapter 4: Modifying Reagents

4.1 CLASSIFICATION OF MODIFYING REAGENTS

Modifying reagents, commonly known as regulators, can be regarded as the most important chemicals in mineral processing, which control the interaction of collectors between individual minerals. With the use of modifying reagents, selective adsorption of collectors on specific minerals can be increased or can be decreased to achieve the separation of individual minerals. Because of the use of modifying reagents, it is possible to isolate individual mineral sulfides of lead, zinc and copper from complex sulfide ores. Similarly, it is possible to selectively separate calcium-containing minerals, such as fluorite, scheelite, and calcite from each other.

Regulating reagents, under different conditions, can show either activating or depressing action in flotation. Therefore, it is not possible to strictly classify regulating reagents into specific groups. A general classification of the modifying reagents is shown in Figure 4-1. The principal classes include inorganic modifying reagents and organic modifying reagents.

Figure 4.1: Classification of modifying reagents

Acids, alkalis and metal salts represent inorganic modifying reagents. Organic modifiers are chemicals that contain polar groups, such as OH, COOH, CO, NH ₂, NH and SO ₃H. On the basis of the character of the polar group, which influences the action of the polymer, organic polymers can be divided into the following four subgroups:

1. Non-ionic polymers are chemicals that contain hydrolyzing polar groups: OH, CO, COOH, but carry no electrical charge.

2. Anionic polymers contain polar groups: COOH, SO ₃H, OSO ₃H.

3. Cationic polymers contain polar groups: NH ₂,...