The addition of frother in flotation has two main functions, to help reduce bubble size and help produce a stable froth. A role of frother on bubble behavior in pulp zone is usually not considered. A previous study showed that as frother type was changed the same gas holdup was given by different size bubbles. This implies that bubble rise velocity depends on the nature of the surfactant (frother type). A study using bubble swarms appears to support the frother type effect but bubble interactions are a possible confounding factor.;To investigate, experiments were performed using aliphatic alcohols from 1-butanol (C4) to 1-octanol (C8). It was found there is a minimum concentration for the frother to give terminal velocity close to the Clift et al. contaminated eater result. The concentration decreases as molecular weight (chain length) of alcohol increases. Larger bubbles (1.8 vs. 1.5mm) require higher minimum concentration.;To study the influence of molecular structure, three 6-C alcohols, 1-hexanol, MIBC and 2-hexanol, were used. The results show that molecular structure influences rise velocity through the position of OH group, and whether the alcohol is straight chained or branched. The observation can make a useful link frother to chemistry for understanding frother influence on bubble rise and possibly its function in flotation.;The influence of three industrial frother, MIBC, F150 and DF250, was studied and it was observed that over the practical concentration range all reduce rise velocity similar to contaminated water and their critical concentration are very low compared to the aliphatic alcohols. In addition, the influence of a salt, NaCl, on bubble rise velocity was compared to MIBC and confirms a previous observation that reported the similar capability of NaCl to act like MIBC.;This study resolved the question by measuring terminal rise velocity profile of single bubbles (ca. 1 to 2 mm) as a function of frother type. It is shown that at the concentrations of interest in flotation, 1-pentanol hardly alters the velocity compared to water alone while F150 (a polyglycol) reduces the velocity by up to 50%. The results become in 1-pentanol bubble did not reach terminal velocity. For high concentration of 1-pentanol (>130ppm) the rise velocity is reduced comparable to F150.
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