| 摘要 |
Oil, water and sand are separated from soil by screening and separation of coarse particles, agitating the soil in a solution of non-ionic biodegradable detergent to promote emulsification of the oil, separating sand from the emulsion, separating the oil in the emulsion from the detergent solution in a coalescing filter (66), and recycling the detergent solution. Preferably the soil and detergent solution is agitated first at low speed (14) to separate any aggregate from the soil, and to provide a homogenized mixture of the soil and the detergent solution, and then agitating the homogenized mixture of the soil and the detergent at high speed (16) to transfer the oil from the soil into an emulsion with the detergent solution. For reduced maintenance of the coalescing filter (66), the emulsion is passed through a hydrocyclone (61) for removing fines before the emulsion is passed to the coalescing filter (66). In a preferred arrangement having one additional washing stage (146), the sand removed from the settling tank (18) is fed along with fines from the hydrocyclone (61) to the additional washing stage (146), where the sand is washed with secondary stage wash liquid. The sand is removed from the wash liquid, and the wash liquid is fed to a flocculation tank (147), where contaminated fines settle and are removed from the wash liquid. The secondary stage wash liquid is recycled from the flocculation tank (147). |
