Electrochemical metallurgical slag recycling
AssigneeElectrasteel, Inc.
InventorsAi Quoc PHAM, Steven FATUR, Philip WAGNER, Adolfredo ALVAREZ
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Abstract
Described herein are various aspects of systems and methods for extracting and isolating re-usable materials from a metallurgical slags such as iron slag, steel slag, blast furnace slag, BOF slag, and/or EAF slag using aqueous acid and base solutions. In some aspects, the acid and base solutions or materials may be produced electrochemically in a salt-splitting acid-base generation (ABG) cell or cell-stack.
Claims106
A method of recycling a first slag, comprising:
- dissolving the first slag with a first acid to form a starting leachate solution;
- wherein the starting leachate solution comprises at least dissolved aluminum ions, dissolved iron ions, dissolved magnesium ions, and dissolved manganese ions;
- first precipitating one or more first precipitated products from the starting leachate solution by combining a first base with the starting leachate solution to increase its pH thereby forming a first pre-plating leachate fraction;
- wherein the one or more first precipitated products comprise one or more precipitated aluminum-containing products;
- wherein the first pre-plating leachate fraction comprises dissolved iron ions, magnesium ions, and manganese ions;
- first electroplating metallic iron from the first pre-plating leachate fraction using a first electrochemical cell, forming electroplated metallic iron and a first post-plating leachate fraction;
- wherein the first post-plating leachate fraction has a reduced concentration of said iron ions compared to the first pre-plating leachate fraction;
- second precipitating one or more second precipitated products from the first post-plating leachate fraction by combining a second base with the first post-plating leachate fraction to increase its pH thereby forming a second leachate fraction;
- wherein the one or more second precipitated products comprise one or more precipitated manganese-containing products;
- and
- third precipitating one or more third precipitated products from the second leachate fraction by combining a third base with the second leachate fraction to increase its pH thereby forming a third leachate fraction;
- wherein the one or more third precipitated products comprise one or more precipitated magnesium-containing products.
The method of any one of the preceding claims, wherein the step of first electroplating metallic iron is performed against an electrochemical oxygen evolution reaction at a first anode.
The method of any one of the preceding claims further comprising:
- producing a produced acid and a produced base in an electrochemical acid-base generator;
- wherein the first acid comprises the produced acid;
- and
- wherein each of the first base, the second base, and the third base comprises a portion of the produced base.
The method of any one of the preceding claims further comprising first providing at least a portion of the first, second, and/or third precipitated products, with or without further processing thereof, to a steelmaking furnace.
The method of any one of the preceding claims, wherein the third precipitated products comprise magnesium hydroxide and/or calcium hydroxide;
- and wherein the method comprises converting the magnesium hydroxide and/or calcium hydroxide to magnesium oxide and/or calcium oxide, respectfully, and providing the magnesium oxide and/or calcium oxide as a flux in a steelmaking furnace.
The method any of the preceding claims, comprising providing at least a portion of the electroplated metallic iron to a steelmaking furnace.
The method of any one the preceding claims, comprising producing at least a portion of each of the first acid, the second acid, the first base, the second base, and the third base using an electrochemical acid-base generator.
The method of any one of the preceding claims, comprising first collecting at least a portion of a spent catholyte from the step of first electroplating and concentrating the collected spent catholyte.
The method of any one of the preceding claims, comprising:
- removing a bleed stream from the first electroplating catholyte.
The method of any one of the preceding claims, wherein a concentration of the dissolved magnesium ions in the first pre-plating leachate fraction is selected from the range of 0.01 M to 1 M.
The method of any one of the preceding claims, wherein a concentration of the dissolved manganese ions in the first pre-plating leachate fraction is selected from the range of 0.01 M to 1 M.
A method of recycling a first slag, comprising:
- dissolving the first slag with a first acid to form a starting leachate solution;
- wherein the starting leachate solution comprises at least one or more dissolved aluminum ions, dissolved iron ions, and dissolved calcium ions and/or magnesium ions;
- first precipitating one or more first precipitated products from the starting leachate solution by combining a first base with the starting leachate solution to increase its pH thereby forming a first leachate fraction;
- wherein the one or more first precipitated products comprise one or more precipitated aluminum-containing products;
- second precipitating one or more second precipitated products from the first leachate fraction by combining a second base with the first leachate fraction to increase its pH thereby forming a second leachate fraction;
- wherein the one or more second precipitated products comprise one or more precipitated iron-containing products;
- and
- third precipitating one or more third precipitated products from the second leachate fraction by combining a third base with the second leachate fraction to increase its pH thereby forming a third leachate fraction;
- wherein the one or more third precipitated products comprise one or more precipitated calcium-containing products and/or one or more precipitated magnesium-containing products;
- wherein the method further comprises:
- producing a produced acid and a produced base in an electrochemical acid-base generator;
- wherein the first acid comprises the produced acid;
- and
- wherein each of the first base, the second base, and the third base comprises a portion of the produced base.
A method of recycling a first slag, comprising:
- dissolving the first slag with a first acid to form a starting leachate solution;
- wherein the starting leachate solution comprises at least one or more dissolved aluminum ions, dissolved iron ions, and one or more dissolved calcium ions and/or magnesium ions;
- first precipitating one or more first precipitated products from the starting leachate solution by combining a first base with the starting leachate solution to increase its pH thereby forming a first leachate fraction;
- wherein the one or more first precipitated products comprise one or more precipitated aluminum-containing products;
- second precipitating one or more second precipitated products from the first leachate fraction by combining a second base with the first leachate fraction to increase its pH thereby forming a second leachate fraction;
- wherein the one or more second precipitated products comprise one or more precipitated iron-containing products;
- and
- third precipitating one or more third precipitated products from the second leachate fraction by combining a third base with the second leachate fraction to increase its pH thereby forming a third leachate fraction;
- wherein the one or more third precipitated products comprise one or more precipitated calcium-containing products and/or one or more precipitated magnesium-containing products;
- wherein the method further comprises:
- providing at least a portion of the one or more third precipitated products as a flux to a steelmaking furnace and/or reducing at least a portion of the precipitated iron-containing products to metallic iron and using said metallic iron in the steelmaking furnace;
- collecting a new steel slag from the steelmaking furnace;
- and
- repeating the method using the new steel slag.
The method of any one of the preceding claims, wherein the step of dissolving comprises separating undissolved solids from the starting leachate solution;
- wherein the undissolved solids comprise silica, titania, and/or calcium sulfate.
The method of any one of the preceding claims comprising milling the first slag to decrease its particle size prior to the step of dissolving said first slag.
The method of any one of the preceding claims, wherein the first acid comprises one or more weak acids.
The method of any one of the preceding claims, wherein the first acid comprises an aqueous bisulfate acid.
The method of any one of the preceding claims, wherein the first acid comprises sulfuric acid.
The method of any one of the preceding claims, wherein the first acid comprises hydrochloric acid.
The method of any one of the preceding claims comprising reducing ferric ions to ferrous ions in the starting leachate solution prior to the step of first precipitating.
The method of any one of the preceding claims, wherein the first base, the second base, the third base, or any combination thereof comprises calcium hydroxide, ferric hydroxide, ferrous hydroxide, metallic iron, and/or magnesium hydroxide.
The method of any one of the preceding claims, where each step of first precipitating, second precipitating, third precipitating, or any combination thereof is performed at liquid temperature selected from the range of 50° C. to 90° C.
The method of any one of the preceding claims, wherein:
- the one or more precipitated aluminum-containing products comprise aluminum hydroxide,
- the one or more precipitated iron-containing products comprise iron(II) hydroxide (ferrous hydroxide),
- the one or more precipitated calcium-containing products comprise calcium hydroxide, and
- the one or more precipitated magnesium-containing products comprise magnesium hydroxide.
The method of any one of the preceding claims, wherein the one or more first precipitated products also comprise one or more precipitated chromium-containing products.
The method of any one of the preceding claims, wherein the one or more first precipitated products also comprise one or more precipitated phosphorous-containing products or one or more precipitate phosphate-containing products.
The method of any one of the preceding claims, wherein the one or more second precipitated products also comprise one or more precipitated manganese-containing products.
The method of any one of the preceding claims, wherein the starting leachate solution has a pH less than 2.5.
The method of any one of the preceding claims, wherein the first leachate fraction has a pH selected from the range of 2.5 to 4.5.
The method of any one of the preceding claims, wherein the second leachate fraction has a pH selected from the range of 6.5 to 9.
The method of any one of the preceding claims, wherein the third leachate fraction has a pH selected from the range of 9.5 to 13.
The method of any one of the preceding claims, wherein the one or more first, second, and/or third precipitated products comprise metal hydroxide products;
- and
- wherein the method further comprises:
- dehydrating at least a portion of the metal hydroxides to form respective metal oxide products.
The method of any one of the preceding claims, wherein the one or more precipitated aluminum-containing products comprise aluminum hydroxide;
- the method further comprising dehydrating precipitated aluminum hydroxide to form alumina (Al2O3) and refining the alumina to aluminum metal in an aluminum smelting process.
The method of any one of the preceding claims, wherein the one or more magnesium-containing products comprise Mg(OH)2 and the one or more calcium-containing products comprise Ca(OH)2;
- and wherein the method comprises contacting the precipitated Mg(OH)2 and/or Ca(OH)2 with a CO2-containing gas to form MgCO3 and/or CaCO3, respectively.
The method of any one of the preceding claims, wherein the steelmaking furnace is an electric arc furnace.
The method of any one of the preceding claims, wherein the first slag is a steel slag or an iron slag.
The method of any one of the preceding claims, wherein the first slag is a ladle slag.
The method of any one of the preceding claims, wherein the one or more the one or more precipitated calcium-containing products comprise Ca(OH)2;
- and wherein the method comprising combining the Ca(OH)2 with silica, alumina, and iron in a kiln and heating to make clinker.
A method of electrochemically making metallic iron in the presence of dissolved magnesium and dissolved manganese, the method comprising:
- first electroplating metallic iron from a first catholyte at a first cathode against an oxygen evolution reaction at a first anode in the presence of a first anolyte;
- wherein the first catholyte comprises dissolved iron ions, dissolved magnesium ions, and dissolved manganese ions;
- wherein the first catholyte and the first anolyte are separated by an anion exchange membrane;
- and
- wherein a first electrochemical cell comprises the first cathode, the first catholyte, the first anode, and the first anolyte.
A method of electrochemically making metallic iron, the method comprising:
- first electroplating metallic iron from a first catholyte at a first cathode against an oxygen evolution reaction at a first anode in the presence of a first anolyte;
- and
- dosing the first catholyte with iron hydroxide during the step of first electroplating;
- wherein the first catholyte comprises dissolved iron ions;
- wherein the first catholyte and the first anolyte are separated by an anion exchange membrane;
- and
- wherein a first electrochemical cell comprises the first cathode, the first catholyte, the first anode, and the first anolyte.
A method of producing a bisulfate solution, the method comprising:
- driving a first sulfate salt solution into an acidifying chamber of an electrochemical acid base generation cell, the first sulfate salt solution having a known concentration of a cations that are counter-ions to sulfate anions in the first sulfate salt solution;
- driving a second sulfate salt solution into a basifying chamber of an electrochemical acid base generation cell, the basifying chamber containing a cathode electrode;
- and
- applying an electric current with an applied magnitude across the cathode and an anode of the cell, wherein applying the electric current drives protons into the acidifying chamber at a rate directly proportional to the applied magnitude of the current;
- wherein the magnitude of the applied current drives protons into the acidifying chamber at a rate that does not exceed a rate of the cations flowing into the acidifying chamber;
- whereby a bisulfate acid solution is formed in the acidifying chamber.
A method of extracting alumina from bauxite ore, comprising:
- dissolving the bauxite ore with a first acid to form a starting leachate solution;
- wherein the starting leachate solution comprises at least one or more dissolved aluminum ions, dissolved iron ions, and one or both of calcium ions and magnesium ions;
- first precipitating one or more first precipitated products from the starting leachate solution by combining a first base with the starting leachate solution to increase its pH thereby forming a first leachate fraction;
- wherein the one or more first precipitated products comprise precipitated aluminum hydroxide;
- second precipitating one or more second precipitated products from the first leachate fraction by combining a second base with the first leachate fraction to increase its pH thereby forming a second leachate fraction;
- wherein the one or more second precipitated products comprise one or more precipitated iron-containing products;
- and
- third precipitating one or more third precipitated products from the second leachate fraction by combining a third base with the second leachate fraction to increase its pH thereby forming a third leachate fraction;
- wherein the one or more third precipitated products comprise one or more precipitated calcium-containing products and/or one or more precipitated magnesium-containing products;
- and
- dehydrating the precipitated aluminum hydroxide to form alumina (Al2O3).
Dependencies are inferred from the claim text.