It is useful to clarify the mechanism of flocculation and dispersion phenomena of fine particles in aqueous suspension for mineral processing and other fine particle processing technologies. In order to investigate the flocculation and dispersion phenomena relating to the zeta potential of mineral particles, particle size distribution curves of suspended particles in aqueous suspensions of quartz, fluorite and mixtures of various proportions of both particles were determined by using a sedimentation balance. Whereas quartz and fluorite particles dispersed in separate acid suspensions of about pH 7 or less, mixtures of various proportions of quartz and fluorite particles floc-culated in a third suspension of the same pH value. This phenomenon may possibly be explained by the heterofloc-culation of quartz and fluorite particles which are negatively and positively charged respectively in the suspension of the same pH value.
We propose a possible model of heteroflocculation, and illustrate the model schematically (Figs. 5 and 7 in the text). In the case of a suspension composed of uniform particle size DS of quartz and fluorite, the model is represented as follows. Assume the suspension is composed of a mixture particles of quartz Nq and fluorite Nf, where N represents the number of particles. Whereas the total number of particles of the mixture NS is equal to Nq+Nf in the case of simple mixing where there is no interaction between quartz and fluorite, the number Ns is smaller than Nq+Nf in the state of heteroflocculation where there is interaction between quartz and fluorite. This is because some larger particles of size DLN are built up by flocculation of smaller particles of size Ds (Fig. 5 in the text).
In the case of a suspension composed of large and small particles whose respective diameters are DL and DS, the model is represented as follows. Assume the suspension is composed of a mixture of large particles of quartz NqL and fluorite NfL. Whereas the total number of the large particles of the mixture NL and that of small particles Ns are equal to NqL+NfL and NqS+NfS, respectively, in the state of simple mixing where there is no interaction between quartz and fluorite, the numbers NL and NS are larger than NqL+NfL, and smaller than Nfs+Nfs, respectively. In the case of heteroflocculation where there is interaction between quartz and fluorite, some particles of size DL are composed of smaller particles of size DS (Fig. 7 in the text). The phenomena occuring in suspensions of mixtures of various proportions of quartz and fluorite may be explained by modifying the model.
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