Effect of sodium silicate on the flotation separation of chalcopyrite and galena using sodium sulfite and sulfonated lignin as depressant

Abstract

• Exploring the inhibitory effect of combination depressant for galena . • Exploring the enhancement effect of Na 2 SiO 3 on combination depressant. • Revealing the inhibition mechanism of combination depressant. • Revealing the enhancing mechanism of Na 2 SiO 3 to combination depressant. A combination depressant SHI was composed of sodium sulfite (Na 2 SO 3 ) and sulfonated lignin (SL) in a 5:1 M ratio. In this study, SHI and sodium silicate (Na 2 SiO 3 ) were employed to inhibit the floatability of galena, and the synergies between agents was explored. Micro-flotation results shown that after 2.4 × 10 −4 mol/L SHI was added, the recovery of galena and fine-galena declined by 53% and 36%, respectively. SHI exhibited excellent depressing efficiency toward galena. In the presence of Na 2 SiO 3 , the inhibitory effect of SHI was more obvious. Zeta potential measurements indicates that SHI and Na 2 SiO 3 altered the potential of galena surface through chemical reaction or adsorption action. The X-ray photoelectron spectroscopy results demonstrate that Na 2 SO 3 in the SHI were reacted with Pb ions on the galena surface and formed PbSO 3 , the SL was adsorbed by the galena surface through hydrogen bonding. In parallel, Na 2 SiO 3 interacted with the mineral surface by generating PbSiO 3. The addition of inhibitors increased the oxidation rate of the galena surface, thereby reducing the adsorption of collectors. Density functional theory simulations shown that Na 2 SiO 3 reduced the bonding energy between the galena surfaces and Na 2 SO 3 , and improved the stability of adsorption.