Demineralization and upgrading of petroleum cokes

A method of processing petroleum cokes, comprising:

• providing a solid green petroleum coke comprising a carbonaceous component and a transition metal component, the carbonaceous component comprising polycyclic aromatic hydrocarbons, wherein the solid green petroleum coke has an elemental composition in wt % of:
• ≥80 carbon ≤98;
• ≥1 hydrogen ≤8;
• ≥2.5 oxygen ≤10;
• nitrogen ≥0.5;
• ≥1 sulfur ≤10;
• ≥0.001 vanadium ≤0.8;
• ≥0.001 iron ≤0.5;
• ≥0.001 nickel ≤0.5;
• ≥0.001 molybdenum ≤0.1;
• and, ≥0.01 cobalt ≤1;
• solubilizing a soluble portion of the solid green petroleum coke in a basic subcritical aqueous solubilization liquid under solubilization conditions that comprise a solubilization pressure of at least 500 psi, a solubilization temperature of from 220° C. to 240° C., and an added solubilization base concentration effective to maintain a solubilization pH≥8, for an effective solubilization time of not more than 2 hours, in the presence of an oxidizing atmosphere comprising more than 21% oxygen, with agitation to generate a stirred reaction region in the solubilization liquid having a Reynolds number of ≥10,000, so as to solubilize at least 75% of the solid green petroleum coke leaving a leached solid residue and producing a pregnant solubilization solution comprising a solubilized organics fraction, wherein the solubilization conditions and effective solubilization time are selected so that the solubilization reaction has a selectivity for production of the solubilized organics fraction over a carbon dioxide gas fraction of at least 80%, and at least 25% of the sulfur in the solid green petroleum coke reports to the leached solid residue, and no more than 60% of the transition metal component of the solid green petroleum coke reports to the pregnant solubilization solution as a dissolved transition metallic component;
• and,
• precipitating a recovered solids fraction from the pregnant solubilization solution by lowering the pH to ≤6, wherein the recovered solids fraction comprises ≥80% of total organic carbon (TOC) present in the pregnant solubilization solution as the solubilized organics fraction, and the recovered solids fraction comprises an acid precipitated transition metal component, wherein the precipitated transition metal component makes up a smaller weight percent fraction of the recovered solids fraction than the weight percent fraction of the transition metal component in the solid green petroleum coke.