STUDY OF LIGNOSULFONATE, ANIONIC SURFACTANTS AND THEIR MIXTURE EFFECT ON ZINC CONCENTRATE PRESSURE LEACHING

PURPOSE. Formation of elemental sulfur under sulfide concentrate pressure leaching leads to the emergence of sulfur-sulfide granules which significantly reduce the rate of zinc dissolution. This problem can be solved through the application of surfactants preventing the negative effect of molten sulfur, and allowing to avoid granule formation under leaching. Lignosulfonates (woodworking industry waste) are the surfactants most widely used for sulfide concentrate pressure leaching. This paper studies the effect of the additives of anionic surfactants and their mixtures with lignosulfonate on the surface tension of aqueous solutions, zinc extraction and grain size distribution of cakes after sulfide zinc concentrate pressure leaching. METHODS. Surface tension of aqueous solutions was determied by a stalagmometric method. Leaching was performed in a titanium autoclave in the presence of lignosulfonate, sodium dodecyl benzene sulfonate and sodium dodecyl sulfate. After leaching the solutions were analyzed on zinc content using an atomic absorption spectroscopy. Grain size analysis of cakes was carried out by a laser diffraction particle size analyzer. RESULTS. The work has shown a synergetic influence of anionic surfactants and lignosulfonate on the decrease of aqueous solution surface tension. The greatest effect has the mixture of lignosulfonate and dodecyl benzene sulfonate (LS-DBS), namely in the range of sodium dodecyl benzene sulfonate (SDBS) concentrations of 400-600 mg/dm³. The use of composite surfactants has allowed to obtain high indices of zinc extraction and optimal particle size of cakes after leaching. When lignosulfonate (LS) and SDBS are used in combination the extraction of zinc increases from 77.2% up to 82.8%, whereas the bulk of the cake (96.7%) has a particle size of -150 μm. CONCLUSION. The composite surfactants (lignosulfonate and sodium dodecyl benzene sulfonate) can be recommended for use at pressure leaching of sulfide zinc concentrates.

zinc concentrates, pressure leaching, surfactants, composite surfactants, gain size distribution analysis, surface tension

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