Mechanism of action of cationic collectors and non-sulfurized ores
The mechanism of action of cationic collectors on non-sulfurized ores, especially silicate minerals, is clearly different from that of anionic collectors:
( 1) The cation collector itself often has foaming properties at the same time;
( 2) sensitive to slime;
( 3) Poor selectivity and strong ability to capture;
( 4) It is mainly physical adsorption of electrostatic force and physical adsorption of molecular force;
( 5) Because of the poor selectivity, the role of the modifier is extremely important.
A commonly used cationic collector for A drug is an amine salt containing 10 to 20 carbon atoms. The main medicinal properties such as dissociation constant, solubility, and critical micelle concentration are listed in Table 1.
Table 1 Â Â Â Important drug properties of dodecylamine Â
Amine salt | Dissociation constant | Solubility of molecular components / mol | Critical micelle concentration ( CMC ) /mol |
Dodecylamine Methyldodecylamine Dimethyldodecylamine Trimethyldodecylamine hydroxide | 4. 3 × 10 -4 1 (strong base) | 2 × 10 -5 1.2 × 10 -5 7.2 × 10 -6 | 0.13 (chlorine salt, 0.016 to 0.02 ( chlorine salt, |
Table 2 Â Properties of different hydrocarbon chain primary amines Â
Chain length | Solubility of molecular components / mol | Critical micelle ( CMC ) /mol |
5 × 10 -4 2 × 10 -4 1 × 10 -6 - - | 3. 2 × 10 -2 1.3 × 10 -2 4.1 × 10 -3 8.3 × 10 -4 4.0 × 10 -4 |
Physical adsorption of B amine ions and molecules The physical adsorption of amine ions and molecules is mainly electrostatic adsorption, including Fan's force adsorption. When dodecylamine ions are adsorbed on the surface of quartz , the effect of dodecyl ester concentration on the dynamic potential of quartz surface, at low concentration, has little effect on the dynamic potential. At this time, there may be adsorption of individual dodecyl cations. When the concentration is increased, it gradually becomes semi-micelle adsorption. When the pH is constant, the potential of the quartz surface is changed to zero. The concentration of the amine salt required is related to the length of the hydrocarbon chain. The longer the hydrocarbon chain, the smaller the concentration of the half micelle, and the pH range suitable for flotation is expanded.
The effect of PH on adsorption and electrical properties: On the one hand, H + and OH - are themselves the localized ions of many minerals; on the other hand, OH - affects the degree of hydrolysis of weakly alkaline collectors. The amine is a weak base, for example, dodecylamine
RNH 2 ( liquid ) + H 2 O ≒ RNH 3 + OH -
K base = | [RNH + 3 ] · [OH - ] | = 4. 3 × 10 -4 |
[RNH 2 ] |
RNH 2 (solid) + H 2 O ≒ RNH 3 + OH -
K solid = [RNH 3 + ][OH - ] = 8. 6 × 10 -9
RNH 2 (solid) ≒ RNH 2 ( liquid )
K solid solution = [RNH 2 ( liquid ) ] = 2 × 10 -5
     According to the above equilibrium formula, the presence of each component of the amine under different pH conditions can be calculated . In the acidic solution, RNH + 3 is the main component. From pH = 7 to 10 , RNH 3 gradually decreases, and RNH 2 (liquid) gradually increases. When pH = 10.65 , the two are equal. PH> 10 .5 due to the occurrence RNH 2 (solid) precipitated, RNH + 3 drastically reduced.
When flotation of quartz with an amine salt, the relationship between the floatable pH of quartz and the pH of the amine molecule precipitate is shown in Table 3 .
Table 3 Â Dodecylamine molecules precipitation relationship PH and PH of quartz flotation
Amine | Molecular precipitation PH | Maximum floatable PH | Maximum contact angle PH |
Total amine concentration / 4 × 10 -4 mol | |||
Primary amine Secondary amine Tertiary amine Quaternary amine | 9.4 9.5 8.0 12.0 | 9.0 8.8 8.0 11.3 | 9.6 9.1 8.0 10.6 |
Total amine concentration / 4 × 10 -5 mol | |||
Primary amine Secondary amine Tertiary amine Quaternary amine | 10.6 10.6 9.1 13.0 | 9.7 - - - | 10.1 10.2 9.0 11.2 |
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