Process and apparatus for separating coarse sand particles and recovering bitumen from tar sands

A system for effecting a sharp separation from tar sands of the large weight fraction of coarse materials present therein and for recovering bitumen, or tar, from the remaining product, wherein, as a first step, finely divided particles of a tar sand are added to a liquid hydrocarbon solvent in an agitation zone to form a dilute solution of the bitumen component which is agitated to maintain both the coarse as well as the fine solid particles present in a well dispersed condition. This dispersion flows downwardly from the agitation zone and through a shallow conduit, generally rectangular in cross section and having an opening extending across its bottom portion over which the dispersion passes. During the short residence time of the dispersion over the opening, the coarse sand particles, which under the influence of gravity fall faster than the fines, selectively drop out of the dispersion and pass through the conduit opening into an underlying sand-receiving chamber. The latter is continuously provided with solvent which wells up into the bitumen solution passing overhead which still contains the fines portion of the dispersion.