Forgot password?
 
  Search thousands of documents on OneMine - the online global mining and minerals library:
 
  Find the industry products
and services you need.
 
   
   
 
 

Minerals & Metallurgical Processing Journal  


Identification of sodium silicate species used as flotation depressants

Minerals & Metallurgical Processing, 2012, Vol. 29, No. 4, pp. 207-210

Silva, J.P.P.; Baltar, C.A.M.; Gonzaga, R.S.G.; Peres, A.E.C.; Leite, J.Y.P.

ABSTRACT:

Sodium silicate (water glass) is a modifier reagent widely used in flotation with the function of a depressant or dispersant. The interaction between sodium silicate and mineral surfaces is still not well understood. This investigation aimed to illuminate the sodium silicate action mechanism as a depressant in the flotation of the minerals quartz and calcite. The experiments were done with high-purity mineral samples in the particle size range below 147 µm. The microflotation tests in a modified Hallimond tube showed that, in all systems tested, the efficiency of sodium silicate increased with the concentration. At concentrations above 1,500 g/t, almost total depression (96% for calcite and 97% for quartz) was achieved. The variation of sodium silicate modulus did not alter the quartz flotation performance in the presence of amine (150 g/t). The most efficient depression pH range was observed between 5 and 8. Above pH 10, the depressant action of sodium silicate was negligible. The infrared spectra obtained at pH 7 after silicate contact showed the presence of the groups OH and Si-OH, both suggesting that the adsorption of the neutral species Si(OH)4, as well as siloxane groups (Si-O-Si), attributed to adsorption of polymeric species. Sharing electron pairs is the proposed adsorption mechanism between Si(OH)4 and polymeric species and the surface sites (Si-O on quartz and Ca-O on calcite). At pH 11, the electrostatic repulsion prevents the species adsorption, impairing the sodium silicate action.
 






 
 
© SME · PH: 303-948-4200 and 800-763-3132 · FAX: 303-973-3845
12999 E. Adam Aircraft Circle, Englewood, CO 80112 - Sitemap
SME is a member society of OneMine, the SME Foundation, and the
American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME).