Influence Of The Interaction Between Inorganic Electrolyte And Surfactant On The Surface Properties And Floatability Of Low Rank Coal

The ability of electrolyte solutions to control the stability of bubbles and the flotation of naturally hydrophobic particles was first documented during 1932-1934. The influence of four kinds of inorganic electrolytes, such as NaCl, CaCl2, MgCl2·6H2O and AlCl3·6H2O, and three surfactants including cationic surfactant lauryl amine, nonionic surfactant Span-80, nonionic surfactant TX-10 on flotation for Pingshuo long-flame coal, Dongpo long-flame coal, Yima long-flame coal and Yima weathered coal were investigated using Hallimond flotation tube. And the interaction mechanism between inorganic salt and surfactant was investigated.Proximate analysis, FTIR and XPS of four coals showed that, Pingshuo long-flame coal, Dongpo long-flame coal and Yima weathered coal are containing more oxygen functional groups and ash. Pingshuo long-flame coal, Dongpo long-flame coal and Yima long-flame coal have obviously -OH,-CH2-,-CH3, aldehyde and ketone groups, but Yima weathered coal basically has no branched alkyl.Foamability research showed that, in solutions and mine slurries, when inorganic electrolyte or both inorganic electrolyte and surfactant were present on solution, average bubble diameter of solutions first became larger and then smaller as the concentration of inorganic electrolyte increased. Bubble diameter have minimum size when concentration of inorganic electrolyte at 0.4mol/L Both inorganic electrolyte and surfactant were present, the air bubbles obtained accumulation on the surface of solution, and bubbles have collecting ability in coal slurries. Surface tension of solutions was decreased by the interaction, in which the interaction NaCl and Span-80, CaCl2 and lauryl amine, MgCl2 and lauryl amine have obviously effects.The change of hydrophobicity of four coals showed that, when concentration of inorganic electrolyte less than 0.2mol/L, the adsorption quantities of surfactant were increased, and the hydrophobicity of raw coal was improved. when concentration of inorganic electrolyte more than 0.2mol/L, the hydrophobicity of raw coal was poor. From the Zeta potential values of four coals found that, the Zeta potential values were removed to positive direction when both inorganic electrolyte and surfactant were present on solutions. The order of influence about Zeta potential is Al3+> Ca2+> Mg2+>Na+, this is caused by the charge and diameter of different ions. For surfactants, cationic surfactants have more obviously effect than nonionic surfactants.Flotation of four coals experiments revealed that the interaction between inorganic electrolytes and surfactant enhanced flotation recovery of coal, compared with traditional flotation agents more suitable for low rank coal flotation, and the interaction of NaCl and Span-80, CaCl2 and lauryl amine, MgCl2 and lauryl amine on flotation have higher recovery. The best flotation recovery of four coals are 51.77%,48.8%,64.01% and 55.65% respectively.