Low-waste process for purification of recycled and natural graphite
OwnerRakan Ashour, Karthik Venkataraman +1inventors
InventorsRakan Ashour, Karthik Venkataraman, Suresh Sriramulu
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Abstract
A process for purifying graphite while minimizing chemical waste. The first step involves a reaction with an alkaline solution (e.g., NaOH) under pressure to remove insoluble oxides such as silica (SiO2) and alumina (Al2O3). The second step involves a leaching reaction with an acid bath to further remove impurities. Each step results in a treated graphite and a filtrate. The filtrate is recovered and regenerated with deionized water or minimal amount of fresh alkali or acid, and repeatedly reused for the purification until the solubility limit of one of the impurities is reached, or the kinetics of the reaction becomes prohibitively slow.
Claims20
A method of producing purified graphite, the method comprising:
- (a) treating a graphite-containing material with an alkaline solution at a temperature above 20° C. and pressure above ambient atmospheric pressure to yield an alkaline-treated graphite and an alkaline filtrate;
- (b) treating the alkaline-treated graphite of step (a) with an acidic solution to yield a purified graphite and an acidic filtrate;
- (c) recovering the alkaline filtrate of step (a) and using at least a portion of the recovered alkaline filtrate to form at least a portion of the alkaline solution used in step (a), and
- (d) recovering the acidic filtrate of step (b) and using at least a portion of the recovered acidic filtrate to form at least a portion of the acidic solution used in step (b).
A method of producing purified graphite, the method comprising:
- (a) treating a graphite-containing material with an aqueous hydroxide solution at a temperature above 20° C. and pressure above ambient atmospheric pressure to yield a hydroxide-treated graphite and a hydroxide filtrate;
- (b) treating the hydroxide-treated graphite of step (a) with an acidic solution to yield a purified graphite and an acidic filtrate;
- (c) recovering the hydroxide filtrate of step (a) and using at least a portion of the recovered hydroxide filtrate to form at least a portion of the aqueous hydroxide solution used in step (a), and
- (d) recovering the acidic filtrate of step (b) and using at least a portion of the recovered acidic filtrate to form at least a portion of the acidic solution used in step (b).
Dependencies are inferred from the claim text.