Partial oxidation of petroleum coke

Claim 1

In a process for the partial oxidation of particulate petroleum coke substantially comprising carbon and containing a small amount of ash comprising vanadium constituents and other materials to produce in a gas generating zone a raw gaseous stream comprising hydrogen and carbon monoxide and containing entrained unconverted particulate petroleum coke comprising carbon and vanadium containing ash, and said gaseous stream is cooled and scrubbed with water in gas cooling and scrubbing zones to produce a cooled and scrubbed clean gas stream and an aqueous dispersion of unconverted particulate petroleum coke; the improvement comprising: (1) mixing said aqueous dispersion of unconverted particulate petroleum coke having a solids concentration in the range of about 0.5 to 20.0 weight percent and a particle size so that 100% passes through ASTM E11-70 Standard Sieve Designation in the range of about 37 microns to less than about 1700 microns with about 0.10 to 0.50 weight percent (basis weight of said aqueous dispersion of unreacted petroleum coke) of a vanadium collection agent to selectively change the amount of vanadium constituents in the unconverted petroleum coke fractions in the froth and bottom layers in step (2); said collection agent being selected from the group consisting of K + amyl xanthate, K + sec-amyl xanthate, and mixtures thereof, and about 0.5 to 5.0 weight percent of a frothing agent to produce froth and selected from the group consisting of pine oil, cresylic acid, C 5 to C 8 carbon aliphatic alcohols, polypropylene glycol, and mixtures thereof; and adjusting the pH of said mixture to a value in the range of about 3 to 10, providing the mixture is not already at said pH; (2) aerating the mixed aqueous dispersion from (1) in a froth flotation zone with a gaseous material from the group consisting of air, nitrogen, carbon monoxide, steam, gaseous mixtures of H 2 and CO, and mixtures thereof, and with or without mechanical agitation, forming a layer of froth which floats on a bottom layer of aqueous dispersion, wherein; (a) said aeration is continued until no more solid particles are visible in the foam and from about 70 to 95 weight percent of the unconverted particulate petroleum coke particles (basis carbon) have floated off in the froth, and said unconverted particulate petroleum coke substantially comprises carbon and also contains a small amount of ash with a decreased amount of vanadium constituents; and (b) the remainder of the unconverted particulate petroleum coke is suspended in the bottom layer of aqueous dispersion and substantially comprises carbon and also contains a small amount of ash with an increased amount of vanadium constituents; where in comparison with the vanadium content of the ash in the unconverted particulate petroleum coke prior to the froth flotation treatment the vanadium content of the ash in the floated portion of unconverted particulate petroleum coke has been decreased about 50 to 85 weight percent; and (3) concentrating the froth layer from (2) (a) in a solids-liquid separation zone to produce a concentrated aqueous slurry of unconverted particulate petroleum coke having a solids concentration in the range of about 10 to 70 weight percent, or alternatively 100 weight percent solids, and said concentrated aqueous slurry or alternatively 100 weight percent solids is mixed with either, (1) dry fresh particulate petroleum coke substantially comprising carbon and a small amount of ash comprising vanadium constituents, or (2) slurries of said fresh particulate petroleum coke in water or in a liquid hydrocarbon fuel, or mixtures thereof; (4) recycling to said partial oxidation gas generating zone at least a portion of the mixture from (3) either with or without a carrier; and (5) separating at least a portion of the water from the bottom layer of aqueous dispersion in a solids-liquid separation zone, and introducing the unconverted particulate petroleum coke substantially comprising carbon and also containing a small amount of ash with an increasing amount of vanadium to a conventional metals recovery zone to recover vanadium.