Concentration at the Minimum Bubble Velocity (CMV) for Various Types of Flotation Frothers
This paper presents the determination of a concentration at the minimum bubble velocity (CMV) for different types of frothers, such as straight and branched alkyl chain aliphatic alcohols, 1,ω-diols, poly(propylene glycol) and poly(ethylene glycol) alkyl ethers, n-alkyltrimethylammonium bromides, commercial frothers and others. The values of terminal rise bubble velocity were reviewed from the experimental data published in the literature for two different types of columns, i.e., a short PAS
... .e., a short PAS (used in Polish Academy of Sciences) of height (35 cm) and a long McGill of height (350 cm). The obtained empirical equation is universal and allows one to rapidly and accurately determine the CMV for all surfactants. The proposed empirical model can also be used to predict the terminal bubble velocity-frother concentration curve by knowing the maximum and minimum terminal velocities, as well as the values of CMV. Assessment and usefulness of frother characterization parameters (i.e., concentration at the minimum bubble velocity (CMV), dynamic frothability index (DFI) and critical coalescence concentration (CCC)) were shown in the flotation of coal. From the practical point of view, it would be very beneficial to determine a methodology, which can be used for the simple characterization and anticipation of frothers' properties in terms of CMV, CCC, CMH and DFI variations, based on basic experimental results, which can be either found in a myriad of published papers or easily determined. In this paper, we show a methodology to obtain an empirical equation allowing the rapid and accurate determination of the value of the CMV for surface active substances commonly used as flotation frothers. In addition, it is shown that the proposed empirical approach can be used to predict the dependence of a rising bubble terminal velocity as a function of frother concentration only by knowing the border velocity values (maximum and minimum) and the CMV for a given system. This approach can also be extended for prediction of the bubble size-concentration curve, where the minimum and maximum bubble sizes, as well as the CCC value, are known.