Introduction of amine collectors
A class of cationic polar collectors in flotation reagents. The polar group (see collector) of the agent contains a nitrogen (N) atom. It is also called a cationic collector because it is a hydrocarbon-containing cation (RNH}). This collector for the flotation of silicate and aluminosilicate minerals, such as quartz, beryl, spodumene, feldspar, mica, and the like; carbonate minerals, such as zinc ore Ling; soluble salts, such as Potassium salt, etc.
The class of amine collectors are mainly amines and their salts. Including primary amine salt (RNH 3 Cl), secondary amine salt (RR'NH 2 cl), tertiary amine salt (R(R') 2 NHcl) and quaternary ammonium salt (R(R') 3 Ncl); Representing a long chain hydrocarbyl or aromatic hydrocarbon group, generally above c 10 ; R' is usually a short chain hydrocarbyl group, typically cH 3. The commonly used amine salt for flotation is primarily an alkane primary amine of 8 to 18 carbon atoms and salts thereof. For example, the synthesis of dodecylamine (c n H 2n NH 2 , n=10-13), cocoamine (c n H 2n +NH 2 , n=8-18), synthesis of octadecylamine (c n+1 NH 2 , n = 17 to 19), mixed amines (C n H 2n+1 NH 2 , n = 10 to 20), etc.; in addition, there is an etheramine (ROCH 2 CH 2 cH 2 NH 2 ) which is an amine in the amine The introduction of an ether group on the base can change the solid amine into a liquid, and the etheramine is easily dispersed in the slurry, and the flotation effect is better. The amine collector may be present in the molecule or in an ionic state in water. Taking dodecylamine as an example, the following equilibrium relationship exists in the aqueous solution:
RNH 2 +H 2 O⇔RNH 3 + +0H - Dissociation constant at equilibrium (at 25 ° C), so the state of the amine in the aqueous solution depends on the pH of the solution. For the aqueous solution of dodecylamine with a concentration of 1×10—jnol/L, when the concentration of amine molecules is equal to the concentration of amine ions, the pH of the solution is lO. 6. The pK value was 3.4. The pK value of the amine reflects the pH or p0H of the medium when its ion concentration is equal to the molecular concentration. pH
Mechanism of action of an amine collector and minerals, mainly physical adsorption, and chemical adsorption semi micelles, etc., studies of goethite, rutile, corundum, kyanite, quartz and other minerals showed adsorption The role of amine collectors and oxidized minerals is closely related to the surface electrical properties of minerals. The basic rule is that the amine collector adsorbs and collects only on the surface of the negatively charged mineral. It mainly relies on electrostatic force and molecular force, and is physically adsorbed on the mineral. For example, the capture of quartz by dodecylamine occurs only at pH > pZc (pH = 2). When the concentration of the agent is low, RNH 3 + electrostatically adsorbs individual amine ions on the surface of the negatively charged quartz. After the concentration reaches a certain critical value, the amine (RNH 3 + ) will form a half micelle adsorption through the association of the hydrocarbon chains. Flotation of the zinc-zinc ore (ZncO 3 ) with an amine collector mainly involves complex chemisorption on the surface of the mineral by covalent bonding of the amine molecule (RNH 2 ) to form a complex [2 n (RNH 2 ) 4 ] 2+ , the amine forms a complex on the surface of the mineral and is adsorbed to make it hydrophobically floated.
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