The mineral processing group of McGill University developed a novel gas holdup probe that consists of two conductivity flow cells: an open cell used to estimate dispersion (slurry + air) conductivity and a syphon cell used to estimate slurry conductivity. These two values are entered into Maxwell's model to calculate gas holdup.; In this work some design criteria for conductivity flow cells and the syphon cell are given. Effect of geometrical cell constant and electrode width on cell behaviour are analyzed. New dimensions for open and syphon cells are proposed. Conditions to prevent bubbles from being entrained into the syphon cell are established.; The new design of the gas holdup probe was tested successfully over a prolonged period at the INCO Matte Separation Plant (Copper Cliff, Ontario). Tests carried out in waste paper de-inking at BOWATER (Gatineau, Quebec) showed the gas holdup values given by the probe agreed with the values obtained from pressure. The noise associated with the gas holdup signal obtained by the probe could be used to diagnose sparger operation.; Gas holdup showed some degree of correlation with flotation efficiency of waste paper de-inking and flotation rate constant. Chemistry and rheology of the feed are other factors to be considered. Estimation of bubble surface area flux should consider rheology properties (liquid viscosity and density).
展开▼
