FLOTATION (Main feature - hydrophobicity)

Flotation

water  gas bubble particle Contact angle

Contact angle of selected materials ( degree)

Methods of measurement

The Young equation g cg sg scg s c  vapor adsorption x x x x x x x x x x x x x x x g cg sg scg s c  vapor adsorption sg = sc+ cgcos s -  = sc+ cgcos liquid drop cieczy

Influence of pH (electrical properties) on flotation

Structure of electrical double layer

(rigid and diffuse layer ) Models of electrical double layer o i j d H+ K+ K+H2O OH- A- A-H2O o Helmholz (flat condenser) Gouy-Chapman (diffuse layer) Stern (rigid and diffuse layer ) Grahame (binding sites) triple layer quadruple i o d ----- H+ OH- o i d----- o -o d o i d---- H+ K+ OH- A- 0 =  0  0 Flat condenser Diffuse condenser

Formation of electrical double layer + n X- or positive surface charge negative place of particle breakage + n Me+      Me  Me  Me  Me  H2O metals ęć    Me Me   Me -  Me  Me  + electrons  Me  O  Me  O   O  Me  O  Me   Me  O  Me  O   O  MeO-  Me  OH  Me  X  Me  X   X  Me  X  Me   Me  X  Me  X   Me  X  X -  X  Me  Me+ + n H+  O  MeOH2+ + n OH- oxides salts particle /water interface

Formation of electrical double layer ½ ¾ Me S H 2 O OH SH + H + + n OH - other lad

Flotation reagents COLLECTORS for hydrophobization FROTHERS for froth creation MODIFIERS for enhancing

COLLECTORS

hydrophobization

Structure of collector CH3CH2CH2CH2 CH2CH2CH2CH2 head (hydrophilic) tail (hydrophobic) COO–

collector renders the surface hydrophobic gas collector particle

Influence of pH and iep on flotation for various collectors

Collectors