菱マンガン鉱-水溶液系の界面性状と浮遊性に関する研究

抄録

The interfacial characteristics of rhodochrosite, which is one of the salt type minerals, were studied mainly in the view point of electrokinetics.
H⁺ and OH^-demand in a rhodochrosite-aqueous solution system was measured by potentiometric titration method. The pH value at the zero H⁺and OH^-demand was pH 7.8 (Fig. 2), and MnCO₃(chemicals) powder also showed the same pH value (Fig. 3).
Rhodochrosite powder was suspended in an aqueous solution adjusted the initial pH value to 4.6, 5.3 or 9.1. And, while stirring, change in pH with time was measured. The results indicated that in any initial pH, after enough time pH would be converging on an equilibrium pH value between pH 7.5 and 7.7. MnCO₃(chemicals) powder suspensions also showed the same result (Fig. 4).
Isoelectric point, indicated by a pH value, was pH 7.6, which was measured by the streaming potential method (Fig. 5).
On the rhodochrosite-aqueous solution system, activities of chemical species at various pH values were calculated on the basis of thermodynamic data (Fig. 6). In Fig. 6 IEP (aq) denotes the condition at zero point of total electric charge of chemical species concerning constituent ions of the mineral. This IEP (aq) was pH 7.8.
Accordingly, on the rhodochrosite-aqueous solution system it became clear that there was a good agreement among pH values at zero H⁺and OH^-demand, equilibrium pH value of the suspension, isoelectric point indicated by teh pH value and IEP (aq).
In determining the potential of rhodochrosite, chemical species playing an important role are Mn⁺⁺and HCO₃^-, and CO₃^--above pH 10, too. H⁺and 0H^-also make an important contribution to determining the potential.
Using sodium dodecylsulphate (SDS) and dodecyl ammonium chloride (DAC) as collectors, Hallimond tube flotation test of rhodochrosite was carried out (Fig. 7). Since the isoelectric point indicated by pH value is pH 7.6, below pH 7.6 rhodochrosite is positively charged, and as shown in Fig. 7, within this pH range SDS, anionic collector, is effective. On the other hand, above pH 7.6 DAC, cationic collector, is effective. Therefore, the adsorption mechanism of this type of collector on rhodochrosite is mainly electrostatic.