Kinjiro Aso

Zeta potential of coal fine-particles in aqueous suspension

Abstract The relation between the zeta potential of coal fine-particles and pH value of suspension in aqueous suspension for different kinds of coal samples was determined by using a rectangular micro-electrophoresis cell. The empirical equation of the relation between the zeta potential of the particles and the chemical components of coal samples was determined in aqueous suspension of different pH values. The equation is represented as follows: Z = B C × (C) + B H × (H) + B O × (O) + B N X × (N) + B S × (S) + B A × (A) where Z is the zeta potential of the particles, (C), (H), (O), (N), (S) and (Ash) are weight percent of carbon, hydrogen, oxygen, nitrogen, sulphur and ash, respectively, and B C , B H , B O , B N , B S and B A are coefficients of each of the respective components of coal samples. The above coefficients were calculated numerically by the least-square method in suspensions with different pH values. The values of the coefficients, B C , B H , etc., (mV/%), indicate the zeta potential of each respective single component; viz. carbon, hydrogen, etc., of the coal samples. When the chemical components of a coal sample are known, the zeta potential of the coal fine-particles can be determined by the equation with the coefficients obtained in suspensions with different pH values.

Flocculation and dispersion properties of quartz and fluorite particles in suspension

Abstract An improved sedimentation balance was developed that has a maximum weighing load of 200 g and weight detection sensitivity of 0.1 mg for the particle size distribution analysis of mineral particles in suspension. The sedimentation balance was used to determine the falling velocity distribution curve (which corresponds to the particle size distribution curve) of suspended particles in aqueous suspensions in order to investigate the flocculation and dispersion properties of quartz, fluorite and a mixture of equal weights of both particles in relation to the zeta potential of mineral particles. Whereas quartz and fluorite particles dispersed in separate acid suspensions of about pH 7 or less, a mixture of equal weights of both quartz and fluorite particles flocculated in a third suspension of about pH 10 or less. This phenomenon is possibly explained by the heteroflocculation of quartz and fluorite particles, which are negatively and positively charged, respectively, in the suspension of about pH 10 or less.

Grindability of Limestone by the Modified Hardgrove Method

Grinding tests of limestone were performed using the Hardgroves testing machine. Energy consumed (E kg. m) by grinding was obtained by the measurement of torque of the axis of the machine. Specific surface area increased (ΔSvcm2/cm3) by grinding was calculated by the size analysis of the products. Grindability was shown as the ratio of ΔSv to E.As a result, the grindability indices of 17 samples of limestone from 14 quarries were ranging 8-18(cm2/cm3)/(kg.m). These values of limestone were larger than those of quartz, feldspar, fluorite, kaolin and bentonite, and smaller than that of talc, and two to five times as large as that of quartz.