Extraction of Rare Earths from Red Mud Iron Nugget Slags with Oxalic Acid Precipitation

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Department of Chemical Engineering


Red mud contains large amounts of rare and valuable minerals. Specifically, rare earth elements are present at a concentrated amount in many red mud samples around the world. There is currently only one ore source in the United States that can produce rare earth elements. Pursuing avenues to extract rare earths from red mud is highly advantageous to reduce the amount of red mud being stockpiled, give value to red mud as a waste, and utilize a source for producing rare earths. The iron nugget process effectively increases the concentration of rare earth elements by removing iron. Slag from the iron nugget process upgraded the concentration of rare earth elements by 100%, which makes this a desirable feed for processing. Hydrochloric acid was used to dissolve the rare earth oxides present in the nugget slags, rare earths were then precipitated as a solid using oxalic acid. HCl leach can recover 170 grams of rare earths per ton of red mud nugget slag and oxalic acid precipitation can recover 45 grams per ton.

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Mineral Processing and Extractive Metallurgy Review