Removal of emulsified oil particles by dispersed air flotation.

Abstract

Dilute emulsified particles (C-300 g nr3, Z)P~8 /mi) of heavy oil A were removed in a 65 mm-diameter, 0.32 m-deep column with a solution of pH 4 which minimized double-layer repulsion.Firstly, flotation by bubbling through glass frits of three different pore sizes shows that the removal rate is proportional to the oil concentration to the first order at low gas velocity (0.01Û g£0.05 cm s"1) and to the second order at high gas velocity (0.1^Ug^3 cm s"1), This fact implies that the predominant rate step is oil particle-bubble collision in the former region and particle-particle collision in the latter. Mechanical agitation by a paddle gives the same removal rate as bubbling in the high gas velocity region when the power consumption per unit volume is the same. This fact implies that the role of bubbling there is to give adequate turbulence to the liquid. Secondly, the bubble diameter was changed from 40 //m to 2 mmunder the mechanism of bubbleparticle collision by electrolysis, dissolved and bubbling air flotation. With increasing bubble

A study on recovery of oil from sludge containing oil using froth flotation

“…The added advantage of flotation is selective recovery of valuable species, like gold, silver, palladium, etc. Flotation is also successfully used to clean up oily waste water and it is an active area of research (Rosa and Rubio, 2005;Gu and Chiang, 1999;Al-Shamrani et al, 2002;Medraycka, 1993;Sato et al, 1980). The mechanism involved in this process consists of several steps, namely: (i) approach of an air bubble and oil drop; (ii) thinning of the water film in between the bubble and drop; (iii) rupture of the water film beyond a critical thickness; (iv) attachment of hydrophobic oil to the air bubble; (v) spreading of oil on the bubble surface; and (vi) rise of the conglomerate faster compared to an unattached oil drop due to its reduced density .…”

The Model of Volatile Hydrocarbons Removal from Their Emulsions in the Flotation Process

“…Sato's experiments on oil particle flotation confirmed the theoretical model based on interception, which was used for the calculation of the collision efficiency (6).…”

“…It was found that the collision efficiency is proportional to the d,, /dh value (6,13,15). According to Reay's empirical relation, the collision efficiency may be calculated by E, = a(d, /db)O, where a and fl depend mainly on the kind of particles and the fluid.…”

Separation of oil-water mixture in tank

“…Hoshino et al (1984) confirmed that a glass fiber filter was much superior to cellulose for filtration of oil-water emulsion. Sato et al (1980) emulsion in a batch process. They observed that the performance was strongly affected by the method of air distributor (porous plate, single hole, or multiple hole plate), initial oil concentration (30À600 mg=L), oil drop size distribution in the feed, surfactant type, and gas superficial velocity.…”