Ultrasound Assisted Ash and Sulphur Removal from Bitumen Using Column Flotation Technique: Experimental, RSM and ANN Methods in Modelling and Optimization of Process

Abstract

To remove ash and pyritic sulphur from bitumen an experimental study was performed to investigate the use of low frequency ultrasound wave in column flotation. For this purpose, a column flotation rig was equipped with a low frequency 24 kHz ultrasound transducer. The bitumen samples had sulphur content of 9.6 % (6.81 % in the pyritic sulphur form) and 26.4 % ash. All the experiments were carried out under pulp containing 5 % of solid, particle size of 100mesh and aeration rate of 4L/min using pine oil and kerosene as frother and collector agents, respectively. The effects of four parameters including the amounts of collector and frother agents, ultrasound power and ultrasound times were investigated. The optimum conditions for column flotation process with assisted ultrasound were; 1.5 kg/tbitumen of collector, 0.4 ppm of frother, ultrasound power equal to 300 W and ultrasound time of 3 min under flotation time of 5 min. In these conditions, 87.72 % of pyritic sulphur (i.e., 68.03 % of total sulphur) and 83.29 % of ash were removed. Accordingly, the enhancement of column flotation yield with ultrasound mode was approximately 11.9 and 10.3 % more than without ultrasound for ash and pyritic sulphur removal, respectively. The effect of process factors including amounts of collector and frother agents, ultrasound power and ultrasound time on ash and pyritic sulphur removal was investigated by central composite design (CCD) of RSM and multilayer feed forward back propagation neural network with the topology of 4-6-1.