Reduction of vanadium in recycle petroleum coke

Abstract

An aqueous dispersion of unreacted particulate petroleum coke substantially comprising carbon and containing a small amount of ash substantially comprising vanadium constituents and other materials from a process for the partial oxidation of petroleum coke to produce synthesis gas is mixed with a hydrocarbon alkoxy sulfate and a frothing agent. After pH adjustment, if necessary, the mixture is subjected to aeration with or without mechanical agitation in a froth flotation zone. About 5 to 25 wt. % of the unconverted particulate petroleum coke (basis carbon) particles float in the froth layer that is formed. The remainder of the unconverted petroleum coke comprising coarser particles is suspended in a bottom aqueous dispersion on which the froth layer floats. In addition, selective separation of the vanadium constituents in the unconverted petroleum coke ash takes place. The vanadium content of the ash in the floated portion of unconverted petroleum coke is unexpectedly increased about 10 to 50 weight percent. Simultaneously, the vanadium content of the ash in the unconverted petroleum coke suspended in the bottom layer of aqueous dispersion is unexpectedly decreased about 5 to 50 weight percent. Water may be recovered from this aqueous dispersion and recycled to the gas quench cooling and scrubbing zones. At least a portion of the unconverted particulate petroleum coke from said bottom aqueous dispersion is recycled to the partial oxidation gas generator as a portion of the feed. The froth is removed from the system and may be sent to a vanadium recovery zone. By the subject process, the vanadium content in the recycle stream to the gas generator of unconverted petroleum coke to the gas generator is reduced. The life of the refractory lining of the gas generator is thereby extended.