Systems and methods for combined co2 storage and metal extraction from ultramafic rock and mine tailings

A method of extracting products from metal-containing feedstocks, comprising:

• providing an amount of one or more feedstocks, the feedstocks including ultramafic rock, mining tailings, or combinations thereof;
• providing an extraction composition fluid including a concentration of dissolved CO2;
• contacting the feedstocks with an amount of the extraction composition fluid and a concentration of one or more reducing agents to form a first reaction mixture, the first reaction mixture having a fluid:solid ratio by weight of extraction composition fluid to feedstock below 10;
• sequestering at least a portion of the dissolved CO2 in the feedstocks;
• isolating a first target product from the first reaction mixture, the first target product including a concentration of Ni, Co, graphite or combinations thereof;
• contacting the feedstocks with an amount of the extraction composition fluid and a concentration of one or more reducing agents to form at least a second reaction mixture, the second reaction mixture having a fluid:solid ratio by weight of extraction composition fluid to feedstock that is different than the first reaction mixture;
• and
• isolating at least a second target product from the second reaction mixture, the second target product including a concentration of Ni, Co, or combinations thereof.

A system for extracting products from metal-containing feedstocks, the system comprising:

• an extraction reactor;
• a source of one or more feedstocks in communication with the extraction reactor, the feedstocks including ultramafic rock, mining tailings, or combinations thereof;
• a feedstream including an aqueous extraction composition fluid in fluid communication with the extraction reactor, the aqueous extraction composition fluid including a concentration of dissolved CO2;
• a source of one or more reducing agents in communication with the extraction reactor, the reducing agents including iron sulfides, metallic iron, metallic aluminum, or combinations thereof;
• a reaction mixture in the extraction reactor, the reaction mixture including amounts of the one or more feedstocks, the aqueous extraction composition fluid;
• and the one or more reducing agents;
• and
• a target product outlet stream, the target product including a concentration of Ni, Co, graphite or combinations thereof,
• wherein the reaction mixture includes:
• a fluid:solid ratio by weight of aqueous extraction composition fluid to feedstock below 10, and
• metallic iron, metallic aluminum, or combinations thereof at a concentration less than about 10 wt %;
• iron sulfides including pyrite, pyrrhotite, or combinations thereof at a concentration less than about 1 wt %;
• or combinations thereof,
• wherein the target product includes sulfide compounds, iron metal-containing alloy, graphite, or combinations thereof.