Dispersion behaviour of fine collophane particles in the presence of different dispersants and metal ions

ABSTRACT

Recent, studies have shown that selective flocculation flotation is an effective method for enhancing the flotation of a fine mineral. Fine-grained collophane is difficult to disperse naturally, thereby affecting its subsequent flotation separation. Therefore, it is important to study the dispersion behaviour and mechanism of fine-grained cellophane to choose an appropriate method to improve the dispersion effect of the flotation system. The influences of different types of poly-anionic dispersants, such as (sodium silicate (ZSS); sodium carbonate (ZSC); sodium hexametaphosphate, ZSP) and metallic cations with different valences (Al³⁺, Ca²⁺, Na⁺) on the dispersion behaviour effect of fine-grained collophane were investigated in this work using the sedimentation balance method. The zeta potential measurements and the extended-DLVO (Derain-Landau-Verwey-Overbake) theory were used to explain the distinction of dispersion behaviour. In the presence of dispersants, the dispersion of collophane was in the order of ZSP>ZSS>ZSC. Zeta potential analysis indicated that the absolute value of the surface potential followed the order of ZSP>ZSS>ZSC. That is, the collophane particles in the ZSP system had stronger electrostatic repulsion, resulting in a better dispersion zeta potential effect zeta potential. ZSP was adopted as dispersant to study the effects of metal ions on dispersion. In the ZSP dispersant system, metal ions can suppress the dispersion behaviour of fine-grained collophane. The suppression effect followed the order of Al³⁺>Ca²⁺>Na⁺, because of the greater charge and better neutralization ability of trivalent ions for the same concentration. The results of the extended-DLVO calculations showed that the dispersion stability was attributed to the electrostatic repulsion and hydration repulsion, and hydration repulsion had a greater influence on the stability than electrostatic repulsion. This paper provides reference information for adjusting the dispersion behaviour effect of fine-grained collophane, thereby guiding the actual flotation separation.

KEYWORDS:

• Fine particle
• collophane
• metal ions
• dispersant
• dispersion behaviour

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China [51474078] and the Key Foundation of Science and Technology of Guizhou Province, China (Qian Ke He JZ [2014] 2009).