Process for recovering ultrafine solids from a hydrocarbon liquid

A process for separating a particulate solid material from a hydrocarbon liquid comprising the following steps:

• a) obtaining a bleed slurry comprising the hydrocarbon liquid and the solid material,
• b) cooling the bleed slurry,
• c) mixing the bleed slurry in a flocculant and to form a first mixture comprising the hydrocarbon liquid, a first solvent and a flocculent containing the solid material,
• d) separating the first mixture in a first centrifuge to form a second mixture and a third mixture, wherein the second mixture contains a low concentration of the flocculent and the third mixture contains a high concentration of the flocculent,
• e) separating the second mixture in at least one second centrifuge to form a fourth mixture comprising the first solvent and the hydrocarbon liquid and a fifth mixture containing a high concentration of the flocculent,
• f) combining the third mixture and the fifth mixture in a feed tank to form a final mixture comprising a high concentration of the flocculent, a low concentration of the first solvent and a low concentration of the hydrocarbon liquid,
• g) drying the final mixture in a drying device to form a hydrocarbon vapor mixture and a coked material wherein the hydrocarbon vapor comprises the solvent, a light fraction of the hydrocarbon liquid and entrained amounts of the solid material and wherein the coked material comprises the solid material and a heavy fraction of the hydrocarbon liquid,
• h) recovering the hydrocarbon vapor mixture from the drying device and separating the entrained amounts of the solid material, the solvent and the light fraction of the hydrocarbon liquid by means of a system of one or more condensers and one or more oil recovery columns,
• i) recovering the coked material from the drying device.