静電選鉱法による水晶の分離に関する研究

抄録

Separation of rock crystal from silicate sands which is a mixture of feldspar, augite, hornblende and andesite by using a inductive singleroll type electrostatic separator has not been made public, because of many difficulties with respect to their electric properties, e. g. the lack of their surface electric conductivity and the similarity in dielectric constant.
The author has developed the idea of preconditioning the surface of sand particles with a solution of electrolytes, and the following results were obtained.
1) The separation of rock crystal from other silicate sands can be accomplished by preconditioning tnem with dilute water solution (2-4%) of electrolyte such as NaCl, KCl, MgCl₂, or an artificial sea-water. In preconditioning sands are immersed in electrolyte solution for a while, filtered, washed by pure water softly and then dried. As a result of this procedure an electro-conductive tiim is rerainea seiectiveiy on the surface of gangue particles, . while such a film is hardly held on the surface of rock crystal particles owing to their smoothness.
2) Quantity of electrolyte abstracted by unit weight of sands increases with the concentration or eiectrulyte solution, being constant in mol with the same kind of sand constituents.
3) As an example, in treating the sands of 1.2-1.6 mm in size, preconditioned by 2 percent NaCl solution, the 50-70 percent of rock crystal was recovered with the purity of 99.69 percent SiO₂, by keeping negative pole at 16, 800 volts and 22.5mm apart from grounded charging roll.