Adsorption Of Sodium Silicate Research Articles

Effect of depressants on flotation separation of magnesite from dolomite and calcite

The flotation separation of magnesite from calcium-containing minerals has always been a difficult subject in minerals processing. This work studied the inhibition effects of carboxymethyl cellulose (CMC), sodium lignosulphonate, polyaspartic acid (PASP) and sodium silicate on flotation behaviors of magnesite, dolomite and calcite, providing guidance for the development of reagents in magnesite flotation. The micro-flotation results showed that among these four depressants, sodium silicate presented the strongest selectivity due to the highest recovery difference, and the flotation separation of magnesite from dolomite and calcite could be achieved by using sodium silicate as the depressant. Contact angle measurement indicated that the addition of sodium silicate caused the largest differences in surface wettability of the three minerals, which was in line with micro-flotation tests. Furthermore, zeta potential test, the Fourier transform infrared (FT-IR) spectroscopy and atomic force microscope (AFM) imaging were used to reveal the inhibition mechanism of sodium silicate. The results indicated that the dominated component SiO(OH)3− of sodium silicate could adsorb on minerals surfaces, and the adsorption of sodium silicate hardly affected the adsorption of NaOL on magnesite surface, but caused the reduction of NaOL adsorption on dolomite and calcite surfaces, thereby increasing the flotation selectivity.

An SFG spectroscopy study of the interfacial water structure and the adsorption of sodium silicate at the fluorite and silica surfaces

Sodium silicate (SS) is often used as a depressant or a dispersant to improve the selectivity of froth flotation. The depressing ability of SS changes with its concentration and the solution pH. However, the depressing mechanism is unclear. In this paper, sum frequency generation spectroscopy was used to investigate the water structure at the mineral-water interface to provide a molecular understanding of SS adsorption and its role in flotation. Our study shows that a significant amount of silicate species adsorbs at the fluorite-water and silica-water interfaces in a wide range of pH, independently of the surface potential. The adsorption layer of silicate species on the fluorite surface can be removed at low pH (acidic condition), but its removal becomes difficult at high pH (basic condition). On the contrary, the adsorption of silicate species at the silica surface is so strong that the adsorbed species cannot be removed at the whole pH range. This finding agrees with flotation results showing that SS can be used as a dispersant for fluorite at pH = 6–8, but it behaves like a depressant at higher pH. Also, SS effectively depresses the silica floatability at the whole range of pH due to its strong interaction with the mineral surface. This work provides the molecular details about the SS adsorption onto the mineral surface which is complementary to the previous macroscopic studies such as FTIR, zeta potential, and XPS measurements.

The effect of sodium silicate depressant on the flotation separation of fine wolframite from quartz

ABSTRACTQuartz could be activated by metal ions dissolved from wolframite surfaces, making it difficult to separate wolframite from quartz. In this study, sodium silicate used as depressant was investigated in the flotation of fine wolframite. Sodium silicate showed the selective depression on the activated quartz, and the flotation separation of fine wolframite could be achieved by depressing quartz. It was revealed that the adsorption of sodium silicate on activated quartz surfaces was more obvious than that on wolframite. Si(OH)4 and species of aqueous sodium silicate preferentially reacted with activated quartz surfaces and prevented the octyl hydroxamic acid adsorption, further decreasing its floatability.

Adsorption of sodium metasilicate on calcium minerals

The adsorption characteristics of sodium silicate on scheelite, calcite, and fluorite minerals were investigated. Adsorption equilibrium took about 60 minutes. Adsorption data show that the Maximum amounts of adsorption of sodium silicate occurs at about pH 9.8. The adsorptivity was in the order of calcite > fluorite > scheelite. The amount of adsorption of sodium silicate increased with the increase in temperature of sodium silicate solutions. The amount of adsorption of sodium silicate decreases in the low concentration range of ferrous sulfate, while in the high concentration range of ferrous sulfate, the adsorption of sodium silicate increases.