Effects of impeller speed and aeration rate on flotation performance of sulphide ore

1 Introduction Aeration rate and impeller speed are important operational variables in flotation and controlling of them is significant for improving the flotation performance. LAPLANTE et al[1, 2] studied the effect of aeration rate on the flotation rate…     

SIMULATION OF AN IMMOBILIZED ENZYME PARTICLE USING β-GALACTOSIDASE ADSORBED TO A PHENOL-FORMALDEHYDE RESIN

The mass transfer and kinetic properties of both soluble and immobilized β-galactosidase were investigated. A reversible enzyme kinetic model was found to best fit the soluble and immobilized enzymatic lactose hydrolysis. A finite difference model was used to simulate the steady state and unsteady state behavior of an immobilized enzyme particle. The performance of the catalyst in a stirred tank reactor was simulated by using the physical properties of the support with the kinetic model and varying the effective substrate diffusivity to fit the data. A sensitivity analysis was performed to evaluate the effect of particle size, diffusivity, external mass transfer coefficient and enzyme loading.     

INFLUENCE OF PULP PULSATION ON THE BATCH FLOTATION OF GALENA

An experimental investigation into the effect of pulp pulsation on the flotation of an artificial mixture of galena and quartz has been conducted. Laboratory experiments have shown that the recovery and kinetics of lead flotation can be improved significantly by pulsating the pulp, while the grade and selectivity of the lead remained virtually unchanged. Pulsation of the pulp led to structural change of bubbles. An increase in the number of bubbles and a decrease in the bubble size resulted in an increase in the gas holdup in the pulp and a likely increase in the bubble-particle collision rate. Likewise, the viscosity of the slurry could be decreased by means of pulp vibration, enhancing mass transfer between the slurry phase and froth phase. At the same time, the energy input by pulp pulsation could help to lower the energy barrier for bubble-particle attachment by lowering the induction time of the attachment. In addition, non-selectively attached particles could be stripped off the bubble surface by the inertial forces acting on the particles during pulsation of the pulp. Image analysis of the froth showed that pulsation resulted in a more stable froth, with more numerous, smaller bubbles with higher loadings.     

CLUSTER ANALYSIS OF MINERAL PROCESS DATA WITH AUTOASSOCIATIVE NEURAL NETWORKS

Experimental results indicate that autoassociative neural networks provide a robust method for the identification of clusters in process data. Cluster identification is accomplished by extracting a single feature from each multivariate data vector. The ranked features can be used to construct a feature curve, which is subsequently used as a basis for partitioning of the data space. In three case studies, involving two sets of ore samples, and a set of flotation froth features, with 11, 13 and 5 variables respectively, the clusters identified with the neural network appeared to be better than those obtained by conventional means.     

Nanowatt operation of monolithic operational amplifiers†

A study was made of two micropowered operational amplifiers to determine degradation of unity gain frequency response, open-loop gain, and slow rate in amplifier circuits and maximum frequency of oscillation in Colpitts and Wein bridge oscillators as programmed. Quiescent current was reduced below specified operating levels into the nanoampere region.