Solvent extraction is an effective technique for treating oily sludge with multiple sediments, small particles and oil content of 10%-20%. The process utilizes an extractant to dissolve the oily sludge. After being stirred and centrifuged, most of the organic matter and oil are extracted from the mud by the extractant; then the extract is recovered for distillation, the solvent is separated from the mixture for recycling, and the oil is used for refining.
 
Solvent extraction is generally carried out at room temperature. The larger the solvent ratio, the better the extraction effect, but when the solvent ratio is large, the extraction equipment will have a larger load and a relatively larger energy consumption. After the extracted oily sludge is distilled, the heavy oil in the oily sludge can be effectively removed, and the oil removal rate can reach above 90%. Due to the high cost, the extraction method has not been applied to oily sludge treatment in refineries, and an extractant of a high performance-price ratio has become the key to the development of this technology.


 
The process experiment uses chloroform solvent to extract and steam to distill oily sludge. The dewatered oily sludge is naturally dried, from which sundries are removed, and then is pulverized. The sludge is dissolved with chloroform, and then use steam to distill and deoil at 320-480°C under a pressure of 0.2MPa. The experimental results show that when the oily sludge is extracted by adding 3 times of extraction solvent, and then is distilled for 45min as per the ratio of 1g oily sludge to 0.5ml water at 400°C, the deoiling rate is up to 80-90%.