Hydrogen-based valorisation of metal-containing feed materials to extract metals

A hydrometallurgical process for extraction and recovery, from a feed material or blend of feed materials, of one or more valuable metals or elements comprising or consisting of:

• precious metals selected from a group comprising or consisting of platinum group metals (PGMs) i.e. platinum, palladium, rhodium, iridium, ruthenium, osmium, gold and silver;
• and/or base metals selected from a group comprising or consisting of aluminum, copper, lead, nickel, cobalt, tin, tungsten, zinc, cadmium and manganese;
• and/or optionally rare elements selected from a group comprising or consisting of rare earth elements, lithium, germanium, gallium, indium, scandium, uranium, thorium, molybdenum and vanadium;
• wherein iron-rich waste in the feedstock is converted into “green steel” or a “green steel” precursor, the process comprising or consisting of the following steps:
• (i) generating hydrogen and optionally carbon and/or oxygen products with the use of a hydrogen generator, including by electrolysis of water or hydrocarbon pyrolysis or reforming, including with the use of renewable energy or waste sources;
• (ii) leaching the feed material or the blend of feed materials, selected from a group comprising or consisting of a sulfide or other concentrated ore, an oxide or laterite ore, a leach residue or a pre-conditioned leach residue, or any combination thereof, under pressure and/or atmospheric conditions and oxidative, neutral or reductive conditions with H2SO4 to generate a slurry comprising metal sulfates and other valuable elements in solution and a solid leach residue comprising valuable metals and other valuable elements, including where the feed material or blend of feed materials is in the form of a mineral sulfide concentrate, pressure or atmospheric oxidative leaching with H2SO4 the feed material or blend to generate a slurry comprising metal sulfates and other valuable elements in solution and a solid leach residue comprising valuable metals and other valuable elements;
• (iii) separating using using filtration, thickening, centrifugation/cycloning, particle size separation techniques, gravity separation, electrostatic separation, the solid leach residue from the solution in the leach slurry;
• (iv) in the case where the valuable metal sulfate in solution is copper, after the separation step (iii), purifying and recovery of copper including by solvent extraction, ion exchange, adsorption, precipitation, cementation, electrowinning or reduction;
• (v) neutralising and purifying, by addition of limestone and optionally air enriched with oxygen generated from the hydrogen generator, the valuable metals other than copper in the separated solution, thereby to form a slurry comprising the purified metals, solid gypsum and iron oxide products and releasing carbon dioxide;
• (vi) optionally, capturing released carbon dioxide produced during the neutralising and purifying step, further optionally using scrubbing agents including amines;
• (vii) separating the solid gypsum and iron oxide products from each other and from the purified metals using filtration, thickening, centrifugation/cycloning, particle size separation techniques, gravity separation, or electrostatic separation;
• (viii) recovering the purified metals after separation including by solvent extraction, ion exchange, adsorption, precipitation, cementation, electrowinning or reduction;
• (ix) optionally reacting the carbon dioxide produced or captured in step (vi), including with the use of scrubbing agents, during the neutralising and purifying step with hydrogen generated by the hydrogen generator to form methanol for sale, storage, or recycling into step (i);
• (x) optionally, alternatively or in addition, utilising the carbon dioxide produced or captured, including with the use of scrubbing agents, during the neutralising and purifying step in an algal production system;
• (xi) recovering remaining iron oxide from the solid leach residue of step (iii), including optionally subjecting the solid leach residue to heat treatment under reducing, neutral or oxidising conditions to form a heat-treated calcine residue, followed by an additional separation of the solid iron oxide from the calcine residue using filtration, thickening, centrifugation/cycloning, particle size separation techniques, gravity separation, magnetic, or electrostatic separation, leaving a remaining siliceous residue optionally comprising valuable metals and other elements for further purification;
• (xii) reacting the separated iron oxide products from step (vii) and step (xi) including by a molten salt electrolysis route to produce oxygen, or alternatively by hydrogen reduction using hydrogen generated by the hydrogen generator in step (i), to produce Direct Reduced Iron (DRI) or sponge iron, thereby forming “green steel” or a precursor thereof and optionally oxygen, depending on the “green steel” or precursor thereof production process used;
• and
• (xiii) optionally capturing released oxygen, when produced in step (xii), for reuse in the hydrometallurgical process.