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MODIFIERS

AUXILIARY FLOTATION REAGENT. MODIFIERS. 1. Activating reagents 2. Depressants 3. Others (t hey modify: pH, coagulation, redox, rheology, etc. ). ACTIVATING REAGENTS. Activating action of hydrolyzing cations. Flotation of quartz in the presence

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MODIFIERS

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  1. AUXILIARY FLOTATION REAGENT MODIFIERS 1. Activating reagents 2. Depressants 3. Others (they modify: pH, coagulation, redox, rheology, etc.)

  2. ACTIVATING REAGENTS Activating action of hydrolyzing cations. Flotation of quartz in the presence of 10–4 M sulfonate (no flotation in the absence of those cations)

  3. Fluoric ions may activate and depress flotation of silicates: a – area of depressed flotation in presence of oleate b) area of activation in the presence of dodecylamine as collector (Manser, 1975)

  4. Depressing reagents Depressants acting through adsorption Depressants acting through redox reactions Depressants acting through reactions with flotation reagents

  5. Depressors acting through adsorption –MC + D = –MD + C D – depressant ion C – collector ion –MC – collector adsorbed or forming surface compound with mineral –MD – depressant adsorbed or forming surface compound with mineral equilibrium const. for bulk reactions Barski’sconstant (relation) equilibrium const. for surface reactions general form of Barski’ relation

  6. [ ] - X » k [ ] y - OH Depressants acting through adsorption pH modifiers (acids and bases) too high and low pH depress flotation of minerals based on attachment of partcles to bubble

  7. Values of parametery for selected mineral-collector system (here pH regulator determines concentration of OH- ions (after Chander, 1988) Mineral – collector y pH range Galena/KEX 0.65 9 – 12 Galena/KDEDTP 0.53 6 – 9 Sphalerite/DEDTC 0.56 6 – 8 Sphalerite/DBDTC 0.72 7.5 – 10 Sphalerite/DADTC 0.75 8 – 11 Chalcopyrite/NaDEDTP 0.71 8.5 – 11 Chalcopyrite/KEX - 11 – 13 Pyrite/NaDEDTP 0.62 4 – 6 Pyrite/KEX - 10 – 12 E - ethyl, D – di, T tio, A- amyl , B- butyl, X- xanthate , P - phosphate , C – carbonate, K- potassium, Na - sodium In highly alkaline environment not working [ ] - X » k [ ] y - OH

  8. Redox depressants

  9. Relationship between flotation recovery of sulfides and potential applied to a platinum wire immersed in aqueous suspension of a sulfide containing ethyl xanthate at 1.44·10–5 kmol/m3. After Richardson and Walker, 1985

  10. Depressants acting through reactions with flotation reagents 2C2H5OC(S)SK + 2K2SO3 + 2KHSO3 + 2O2 2C2H5OC(S)SOK  2C2H5OH + 4K2S2O3 + 2CO2 Removal of xathates from sulfides

  11. Dispersion modifiers Acids, bases, large organic ions iep

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