Reaction mechanism and application of sodium hydroxide and sodium carbonate

Adjuster is one of the flotation agents. Agents used to change the surface properties of minerals and characteristics of slurry (such as liquid phase composition, foaming performance, foam properties, etc.), improve the selectivity of the flotation process, and improve flotation conditions. According to its main role in the flotation process, it can be divided into inhibitors, activators, acid-base regulators, flocculants, etc.
Sodium hydroxide and sodium carbonate are one of the important adjusters

Adjuster-Reaction Mechanism and Application of Sodium Hydroxide
Sodium hydroxide is a strong alkaline medium regulator. Only when high-alkali medium flotation must be used and lime cannot be used as a medium regulator, sodium hydroxide can be used as a high-alkali medium regulator. For example, when carboxylic acid collectors are used for forward flotation of hematite and limonite or reverse flotation of quartz, in order to avoid the harmful effects of Ca(2+), sodium hydroxide is often used as a high-alkali medium regulator.

Regulator-Reaction Mechanism and Application of Sodium Carbonate
Sodium carbonate (soda ash) is a medium alkaline medium adjuster that can adjust the pH value of the slurry to 8 to 10 or activate pyrite that is inhibited by stone reaction ash. It can precipitate Ca(2+) and Mg(2+) plasma in the slurry and eliminate its harmful effects, which can be expressed as: Na2CO3+2H2O→2Na(+)+2OH(-)+H2CO3H2CO3→H(+)+ HCO3(+) K=4.2×10-7HCO3(-)→H(+)+CO3(2-) K2=4.8×10-1Ca(2+)+CO3(2-)→CaCO3↓Mg(2+)+CO3 (2-)→MgCO3↓Sodium carbonate is mainly used as a medium alkaline medium regulator for non-sulfide mineral flotation. When flotation separation of polymetallic sulfide minerals, if sodium carbonate is used as a medium alkaline medium regulator, more carbonate precipitates will be generated in the slurry, and the mineralized foam will entrain a large amount of mud and become sticky, which can greatly reduce the concentration of the concentrate. To improve the grade and improve the moisture content of the filtered concentrate, sodium carbonate should be used as a medium alkaline medium adjuster as little as possible.