In order to improve the refractoriness of low grade Amakusa pottery clay which is composedof quartz, feldspar (albite) and clay minerals, we have investigated the possibility of the application of flotation process for the removal of feldspar from the clay. The resultsobtained from batch flotation tests and particle size analysis on the flotation products are summarized as follows:
1) In the first stage, clay minerals are separated from quartz and albite by clay flotation in acid circuit. In the second stage, albite in non-float of the clay flotation is separated from quartz in the presence of hydrofluoric acid by feldspar flotatio Ann.d pottercy layp roducti n whicha lbities r emovedt o some extenct an be producedb y mixingt Hef loaotf clay flotation with non-float of feldspar flotation. Especially, it was effective to add the small amount of COAC (Coco amine hydrochloride) as collector stepwise.
2) Following optimum flotation conditions were determined. i) Clay flotation; pulp density 10%, flotation pH 2.7 (adjusted with H2SO4), COACas collector 50×4g/t (a 50g/t of COAC is stepwise added four times.), pine oil as frother 170g/t, ii) Feldspar flotation; pulp density 10%, flotation pH 2.1 (HF 20kg/t), COAC 200×4g/t, pine oil 170g/t.
3) In the early stage of clay flotation, coarse particles tend to float, however, in that of feldspar flotation, fine particles tend to float.
4) In clay flotation, quartz and albite of fine particles (-5μm) have a tendency to be incorporated into float in comparison with those of coarse particles. But in feldspar flotation, quartz of coarse particles (+10μm) have a tendency to be incorporated into floatin comparison with those of fine particles.
5) The refractoriness of pottery clay product by two stage flotation was improved from SK 15 to SK 18.
