STABILIZATION AND PARTIAL DEASPHALTENING OF THERMAL RESIDUES BY CHEMICAL TREATMENT

Thermal processes can be used to produce fuel oils and bitumens or can be applied to recover oil from shales. Thermal residues and bitumens (visbreaker bitumens) are normally less stable than straight run produ cts and contain more asphaltene. This paper proposes a new way to stab ilize thermal residues and bitumens by chemical treatment. The process is based on the fact that thermal residues contain chemical species w ith unpaired electrons. They are reacted with small percentages of pho sphoric acid (from 0.2 to 5 wt %) in order to produce a carbonaceous i nsoluble matter which is settled or centrifuged. The stabilized produc t has a better resistance to aging and may contain less asphaltene tha n the original sample. Phosphoric acid is recovered from the insoluble matter and recycled to the process. Once free from the entrapped oil and from phosphorus, the insoluble residue ranges from 1 to 16 wt % of the original bitumen, depending on the amount of phosphoric acid adde d and On the quality of the bitumen sample. A ''light'' stabilizing tr eatment or a ''heavy'' deasphaltening process can be applied. The inso luble residue can be used as solid fuel, a component of coal-water emu lsions, carbon black, or active carbon.