Selective Extraction of Metals From Complex Inorganic Sources
Compositions and methods are provided that permit both recovery of at least two metals from industrial waste materials and control of the degree of relative recovery between the two metals. Industrial waste is initially treated with an acid and mixed for a defined period of time, and the extracted metals recovered from the resulting supernatant in subsequent steps. Surprisingly, the duration of this initial stirring period has been found to impact the relative degree of recovery of the two metals in a non-linear fashion.
1 - 12 . (canceled)
13 . A method of controlling distribution of metal recovery from a complex inorganic source between a first metal and a second metal, comprising:
contacting the complex inorganic source comprising the first metal and the second metal with an acid to form a first suspension;
mixing the first suspension for a period of time;
upon completion of the period of time, separating the first suspension into a first filtrate and a first solid residue, wherein the first filtrate comprises the first metal and the second metal;
contacting the first filtrate with a first precipitating agent to form a second suspension;
separating the second suspension into a second filtrate and a second solid residue, wherein the second solid residue comprises a portion of the first metal;
contacting the second filtrate with a second precipitating agent to form a third suspension; and
separating the third suspension into a third filtrate and a third solid residue comprising a portion of the second metal,
wherein the period of time is selected to provide a desired recovery distribution between the first metal and the second metal, and
wherein the first precipitating agent is selected from the group consisting of an organic acid, oxalic acid, an organic amine, ethanolamine, an ethanolamine salt, ammonia, and an ammonium salt, and wherein the second solid residue comprises an alumina-containing gel.
14 . The method of claim 13 , wherein the first metal is aluminum and the second metal is calcium.
15 . The method of claim 13 , wherein the acid has a pKa below 5.
16 . The method of claim 13 , wherein the period of time is from 1 minute to 2 hours, and wherein the desired recovery distribution is skewed towards the first metal.
17 . The method of claim 13 , wherein the period of time exceeds 25 minutes, and wherein the desired recovery distribution is skewed towards the second metal.
18 . The method of claim 13 , wherein the second precipitating agent is selected from the group consisting of CO 2 , carbonic acid, a carbonate salt, a bicarbonate salt, a phosphate salt, a sulfate salt, and oxalic acid.
19 . The method of claim 13 , wherein separation is performed by at least one of settling, decanting, centrifugation, use of a cyclone separator, and filtration.
20 . The method of claim 13 , wherein the steps of contacting, mixing, and separating are performed sequentially in a single reaction enclosure.
21 . The method of claim 13 , wherein the steps of contacting, mixing, and separating are performed sequentially in two or more reaction enclosures.
22 . The method of claim 13 , wherein the first solid residue is additionally processed to recover additional metals that are different from the first and second metals.
23 . The method of claim 13 , wherein the complex inorganic source is an industrial waste.
24 . The method of claim 23 , wherein the industrial waste is selected from the group consisting of blast furnace slag, ladle slag, basic oxygen furnace slag, desulfurization slag, and aluminum-rich ores and wastes.