In order to prevent sphalerite particles from aggregating in leaching solution, and to reduce the loss of organic solvent, the surface modification of sphalerite with sodium alginate was investigated. The modified sphalerite particles were characterized by dispersion experiments, determination of adsorption rate of oil, FT-IR spectra and X-ray photoelectron spectra. The results showed that the modified sphalerite particles exhibited good dispersibility in water. The contact angle between sphalerite particles and water changed from 86.9 degrees before modification to 0 degrees after modification with sodium alginate. The sedimentation volume reduced from 0.85 ml/g to 0.70 ml/g. The adsorption rate of oil reduced from 0.15 ml/g to 0.07 ml/g. The checking results of FT-IR and XPS spectra indicated that some modification reagents were coated on the particle surface. The modifier combined to sphalerite particle surface through the chemical bond, resulting in the comprehensive stability action of static and steric effect. (c) 2005 Elsevier B.V. All rights reserved.