Depressing effect of fine hydrophilic particles on magnesite reverse flotation

Abstract

The influence of fine particles on the flotation separation of minerals is becoming increasingly important as new, fine grained deposits are exploited. Fine particles float poorly and less selectively under normal flotation conditions, having detrimental effects on recovery of other minerals. The reasons of this interacting effect are complex, which may be entrainment, pH variation, dissolved ions from mineral surfaces, aggregation/dispersion and coating behavior of particles or even the competitive adsorption effect. In this study, the influence of fine magnesite and dolomite on the flotation of quartz was investigated. It was found that at pH=9.2~9.5 and with DDA dosage of 8.6×10 −4 , the recovery of coarse (-100+65µm) quartz was reduced dramatically from 96.66% to 37.15% when the content of quartz was 5% in the flotation with fine (-5µm) magnesite, and when the content of fine dolomite was increased from 2.5% to 20%, the recovery of coarse quartz was reduced from 91.20% to 75.08%. To examine the reasons, zeta potential, zero point of charge and contact angles of magnesite, dolomite and quartz were measured in the absence and presence of dodecylamine (DDA). The interaction energies between particles were then calculated. Results showed that the aggregation behavior of mineral particles was likely to be the reason. Interaction energy calculated based on Extended-DLVO (Derjaguin-Landau-Verwey-Overbeek) theory predicted that in DDA surfactant solution, the interaction forces between magnesite and quartz, dolomite and quartz were attractive, between dolomite and magnesite was repulsive. The experimental results are in excellent agreement with the theoretically predicted results. The aggregation caused by interacting behavior explains the depressing effect of fine hydrophilic particles on magnesite reverse flotation.

Effects of Metal Ions on the Flotation of Apatite, Dolomite and Quartz

“…Figure 8 shows the zeta potential of quartz as a function of pH in the absence and presence of calcium ions. The IEP of quartz in distilled water was observed around pH = 2, which was in good agreement with results reported by other researchers [33][34][35]. It can be seen that the IEP values did not change with the increase of calcium ion concentration, but the quartz surface was less negatively charged in the presence of Ca 2+ above pH 3.4.…”

A Review of Flotation Separation of Mg Carbonates (Dolomite and Magnesite)

“…ZP measurements have revealed that cationic and anionic collectors have pronounced effects on the surface charge of Mg carbonate minerals (Table 2). It has been observed that cationic collector dodecylamine (DDA) shifts the IEP of Mg carbonates to basic pH 9, and exhibits negative ZP up to pH 12 [23]. On the other hand, with anionic collector sodium oleate (NaOl), Mg carbonates experience negative ZP from pH 3 to 11 [34]; it can also be noted that the ZP of Mg carbonates become negative with increased NaOl concentration [31].…”

Elimination of the Adverse Effect of Calcium Ion on the Flotation Separation of Magnesite from Dolomite

“…Magnesite (MgCO 3 ) is the main source of magnesium oxide mineral, and is used in metallurgy, construction, the chemical industry, and other fields [1,2]. As the market demand for magnesium oxide mineral is increasing, the amount of high quality magnesite is gradually decreasing.…”