Filtration technique enhanced by electro-acoustic methods

Abstract

Results from an experimental study of electric and/or ultrasonic field assisted filtration are presented. Both electric and ultrasonic fields can reduce fouling of the filtration medium and have significant influence on filtration capacity. The extent of filtration improvement is affected mostly by particle size, surface charge, acoustic frequency, and field strengths. Theoretical examinations of the use of electric field and/or ultrasonic field to enhance filtration efficiency were laid out. Some aspects regarding orthokinetic interaction in acoustic agglomeration were considered. Energy consumptions of the filtrations of different suspensions used in experiments were also determined. For pyrite suspension the best results with ultrasound were obtained when filtration was done as follows: 15-s negative pressure filtration, 15-s negative pressure filtration with 22-kHz ultrasonic burst (0.5 s) and 20-s drying with negative pressure. In this case the moisture content of cake was 7% while in the reference cake it was 14%. The cake capacity was fourfold greater than in the reference case. The best results for phosphoric acid were obtained when combined use was made of the ultrasound and the electric field. In this case the filtration capacity increased fifteenfold while the use of ultrasound on its own increased the filtration capacity tenfold.