Recovery and hydropyrolysis of oil from Utah's tar sands

During the past five years, new technology has been developed for fast flotation of Tar Sand with an air-sparged hydrocyclone. Conventional flotation in a stirred, aerated tank requires retention times on the order of minutes, whereas intrinsic bubble attachment times are on the order of milliseconds. This rate limitation for conventional flotation is due to the low probability of collison events, insufficient particle inertia to penetrate the bubble film and instability of bubble/particle aggregates. The design of the air-sparged hydrocyclone was envisioned to establish a controlled, high force field by swirl flow of the slurry to increase the inertia of fine particles and to produce, by introducing air through a porous cyclindrical wall, a high density of fine bubbles with directed motion orthogonal to the particles to improve collision efficiency. The net result is a flotation rate with retention time approaching intrinsic bubble attachment times. This corresponds to a capacity on the order of 1-2 tpd/ft of cyclone volume, at least 50 times the capacity of conventional flotation cell of comparable volume. In this regard, research was initiated to test the effectiveness of air-sparged hydrocyclone in the flotation of bitumen from digested tar sand slurry prepared according to the conditions and procedures that had been established from previous DOE sponsored research on the hot water processing of the Utah tar sands.