# US 5,700,308 A · Method for enhancing reaction rates in metals refining extraction, and recycling operations involving melts containing ionic species such as slags, mattes, fluxes > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,700,308 A - Document ID: US5700308A - Status: Granted - Kind: A - Application number: 08/375,866 - Filed: 1995-01-20 - Granted: 1997-12-23 - Earliest claimed: 1995-01-20 - Assignees: Massachusetts Institute of Technology - Inventors: Uday B. Pal; Julian Szekely - Web page: https://patentgrep.com/patent/US5700308A ## CPC - C22B 4/005: {using plasma jets (smelting, remelting, refining of metals using a plasma as heat source C22B9/22; generating or handling plasma in general H05H1/00; gas-filled discharge tubes for processing materials in general H01J37/32)} - C21C 5/52: Manufacture of steel in electric furnaces {(C21C5/005 takes precedence)} - C21C 5/56: Manufacture of steel by other methods (making liquid steel by direct processes C21B13/00 {; C21C5/005 takes precedence}) - Y02P 10/20: Recycling - C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS - C21C: PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A method and apparatus for enhancing reaction rates between ionic species such as slags, mattes, fluxes and the like with at least another component such as similar melts, metals, chemical compounds, gases or any combination thereof during metal processing operations is provided. A dispersion of the ionic species and the other component or components is formed and contacted with a plasma or electric arc such that migration of the ionic species is facilitated and space charges in the ionic species are discharged. Reactions for decarburization, dephosphorization, desulfurization, deoxidation, alloy additions, refining, extractions and recycling processes on an industrial scale are thereby enhanced. ## Claims ### Claim 1 A process for enhancing reactions between a molten metal and a slag comprising: contacting the slag and the molten metal such that at least a portion of the metal is dispersed in the slag, thereby generating a slag-metal dispersion; discharging space charge within the slag-metal dispersion by contacting the slag-metal dispersion with arc means; and maintaining and regenerating the slag-metal dispersion such that additional space charges in the slag-metal dispersion are discharged. ### Claim 2 (depends on 1) The process of claim 1, wherein the arc means comprises a plasma arc. ### Claim 3 (depends on 1) The process of claim 1, wherein the arc means does not penetrate the molten metal. ### Claim 4 (depends on 1) The process of claim 1, wherein the arc means comprises an electric arc. ### Claim 5 (depends on 1) The process of claim 1, wherein the arc means penetrates the molten metal. ### Claim 6 (depends on 1) The process of claim 1, wherein the dispersed metal is in the form of droplets. ### Claim 7 (depends on 6) The process of claim 6, wherein the space charges in the dispersion surround the metal droplets. ### Claim 8 (depends on 1) The process of claim 1, wherein the dispersion contains at least 5-50% by weight metal dispersed in the slag. ### Claim 9 (depends on 1) The process of claim 1, wherein the process is steelmaking and the dispersion is maintained at a temperature of about 1500.degree.-1700.degree. C. ### Claim 10 (depends on 9) The process of claim 9, wherein the temperature of the dispersion is maintained at about 1600.degree. C. ### Claim 11 (depends on 1) The process of claim 1, wherein the metal contains iron. ### Claim 12 (depends on 1) The process of claim 1, further including adding variable valency cations to the slag such that electrons in the slag are consumed or generated and the discharges of the space charges are thereby enhanced. ### Claim 13 (depends on 12) The process of claim 12, wherein the variable valency cations are selected from the group consisting of iron, titanium, niobium, vanadium, cobalt and copper. ### Claim 14 (depends on 1) The process of claim 1, wherein the slag-metal reaction is decarburization. ### Claim 15 (depends on 1) The process of claim 1, wherein the slag-metal reaction is dephosphorization. ### Claim 16 (depends on 1) The process of claim 1, wherein the slag-metal reaction is desulfurization. ### Claim 17 (depends on 1) The process of claim 1, wherein the slag-metal reaction is deoxidation. ### Claim 18 (depends on 1) The process of claim 1, wherein the slag-metal reaction is alloy addition. ### Claim 19 (depends on 1) The process of claim 1, wherein the process is smelting. ### Claim 20 (depends on 19) The process of claim 19, wherein the smelting is iron carbide smelting. ### Claim 21 (depends on 1) The process of claim 1, wherein the dispersion is generated and maintained by gas agitation. ### Claim 22 A process for enhancing reactions during metals recycling operations, comprising: (a) combining metal scrap and slag forming fluxes, the metal scrap having at least one component to be refined therein; (b) introducing at least one additive into the metal scrap and the slag forming fluxes; (c) generating a slag-metal dispersion with the slag forming fluxes, the metal scrap and the at least one additive; (d) contacting the dispersion with arc means such that space charges within the slag-metal dispersion are discharged and such that the at least one additive reacts with the at least one component in the metal scrap to form a compound which is absorbed into the slag, thereby removing the at least one component from the metal scrap; and (e) maintaining and regenerating the slag-metal dispersion such that additional space charges in the slag-metal dispersion are discharged. ### Claim 23 (depends on 21) The process of claim 21, wherein the gas is selected from the group consisting of oxygen, argon, carbon dioxide, nitrogen and mixtures thereof. ### Claim 24 (depends on 23) The process of claim 23, wherein the gas is injected at a rate of about 2.2N liters/kg metal-minute. ### Claim 25 (depends on 21) The process of claim 21, wherein the gas is substituted with a second gas during the process. ### Claim 26 (depends on 25) The process of claim 25, wherein the second gas is selected from the group consisting of argon, carbon dioxide, nitrogen and mixtures thereof. ### Claim 27 (depends on 23) The process of claim 23, wherein the oxygen flow rate is decreased at a preselected rate during the process. ### Claim 28 (depends on 27) The process of claim 27, further including providing substitute gas sufficient to maintain the dispersion as the oxygen flow is decreased. ### Claim 29 (depends on 28) The process of claim 28, wherein the substitute gas is selected from the group consisting of: argon, carbon dioxide, nitrogen and mixtures thereof. ### Claim 30 (depends on 29) The process of claim 29, wherein the substitute gas is argon. ### Claim 31 A process for increasing carbon oxidation in a metal melt, comprising: contacting a slag having iron oxides therein and the metal melt such that at least a portion of the metal is dispersed in the slag, thereby forming a slag-metal dispersion containing metal droplets suspended in the slag; discharging space charge within the slag-metal dispersion by contacting the slag-metal dispersion with arc means such that carbon is oxidized and removed from the metal melt; and maintaining and regenerating the slag-metal dispersion such that additional space charges in the slag-metal dispersion are discharged. ### Claim 32 (depends on 31) The process of claim 31, wherein the arc means comprises a plasma arc. ### Claim 33 (depends on 31) The process of claim 31, wherein the arc means comprises an electric arc. ### Claim 34 (depends on 31) The process of claim 31, wherein the dispersion is formed and maintained by gas agitation. ### Claim 35 (depends on 34) The process of claim 34, wherein the gas agitation is injected through at least one tuyere. ### Claim 36 (depends on 34) The process of claim 34, wherein the gas is injected through a plug. ### Claim 37 (depends on 34) The process of claim 34, wherein the gas is injected through at least one lance. ### Claim 38 (depends on 31) The process of claim 31, wherein the metal contains iron. ### Claim 39 (depends on 31) The process of claim 31, further including injecting iron oxide into the slag. ### Claim 40 (depends on 39) The process of claim 39, wherein the iron oxide is injected through a submerged lance. ### Claim 41 (depends on 31) The process of claim 31, further including injecting oxygen into the system such that the oxygen facilitates the generation and maintenance of the dispersion and reacts with the metal. ### Claim 42 (depends on 41) The process of claim 41, wherein the oxygen is injected through a submerged lance. ### Claim 43 (depends on 39) The process of claim 39, further including injecting oxygen into the system such that the oxygen facilitates the generation and maintenance of the dispersion and reacts with the metal. ### Claim 44 (depends on 43) The process of claim 43, wherein the oxygen is injected through a submerged lance. ### Claim 45 (depends on 31) The process of claim 31, wherein the process is an argon-oxygen decarburization (AOD) process. ### Claim 46 (depends on 45) The process of claim 45, further including injecting iron oxide into the slag. ### Claim 47 (depends on 46) The process of claim 46, wherein the iron oxide is injected through a submerged lance. ### Claim 48 (depends on 31) The process of claim 31, wherein the process is a vacuum oxidation decarburization (VOD) process. ### Claim 49 (depends on 48) The process of claim 48, further including injecting iron oxide into the slag. ### Claim 50 (depends on 31) The process of claim 31, wherein the process is a vacuum degassing process. ### Claim 51 (depends on 50) The process of claim 50, further including injecting iron oxide into the slag. ### Claim 52 (depends on 31) The process of claim 31, wherein the process is a basic oxygen process (BOP). ### Claim 53 (depends on 52) The process of claim 52, further including injecting iron oxide into the slag. ### Claim 54 (depends on 53) The process of claim 53, wherein the iron oxide is injected through a submerged lance. ### Claim 55 (depends on 52) The process of claim 52, further including injecting oxygen into the system at a preselected flow rate such that the oxygen facilitates the generation and maintenance of the dispersion and reacts with the metal. ### Claim 56 (depends on 55) The process of claim 55, wherein the oxygen flow rate is decreased at a preselected rate during the process. ### Claim 57 (depends on 55) The process of claim 55, further including injecting iron oxide into the slag. ### Claim 58 (depends on 57) The process of claim 57, wherein the iron oxide is injected through a submerged lance. ### Claim 59 (depends on 31) The process of claim 31, further including adding variable valency cations to the slag such that electrons in the slag are consumed or generated and the discharges of the space charges are thereby enhanced. ### Claim 60 (depends on 59) The process of claim 59, wherein the variable valency cations are selected from the group consisting of iron, titanium, niobium, cobalt and copper. ### Claim 61 A process for enhancing reactions during copper smelting processes, comprising: (a) combining a matte having sulfides of copper and iron with slag forming fluxes to form a matte-flux system; (b) contacting the matte-flux system with an oxidizing agent and arc means such that the iron sulfide is oxidized and forms a slag with the flux; (c) oxidizing the copper sulfide into copper and sulfur containing gases; (d) substantially simultaneous with steps (a)-(c), generating a dispersion with the matte, the slag and a metal and contacting the dispersion with arc means such that space charges within the dispersion are discharged; and (e) maintaining and regenerating the slag-metal dispersion such that additional space charges in the slag-metal dispersion are discharged. ### Claim 62 (depends on 61) The process of claim 61, wherein the oxidizing agent is oxygen. ### Claim 63 A process for enhancing reactions during metals extraction processes, comprising: (a) combining a matte having metal sulfides with slag forming fluxes to form a matte-flux system; (b) contacting the matte-flux system with an oxidizing agent and arc means such that the metal sulfide forms a metal oxide in a slag; (c) reducing the metal oxide into the corresponding metal; (d) substantially simultaneous with steps (a)-(c), generating a dispersion with the matte and the slag and contacting the dispersion with arc means such that space charges within the dispersion are discharged; and (e) maintaining and regenerating the slag-metal dispersion such that additional space charges in the slag-metal dispersion are discharged. ### Claim 64 (depends on 63) The process of claim 63, wherein the metal sulfide is selected from the group consisting of sulfides of: zinc, lead and nickel. ### Claim 65 (depends on 63, 64) The process of claim 63 or 64, wherein the reducing agent is selected from the group consisting of carbon containing compounds and hydrogen containing compounds. ### Claim 66 (depends on 22) The process of claim 22, wherein the arc means comprises an electric arc. ### Claim 67 (depends on 22) The process of claim 22, wherein the at least one component in the metal scrap is selected from the group consisting of copper, zinc, lead and nickel. ### Claim 68 (depends on 22, 67) The process of claim 22 or 67, wherein the metal scrap comprises iron scrap. ### Claim 69 (depends on 22, 23) The process of claim 22 or 23, wherein the at least one additive is a sulfur additive. ### Claim 70 (depends on 22) The process of claim 22, wherein the dispersion is generated by gas agitation. ### Claim 71 (depends on 61) The process of claim 61, wherein the arc means comprises a plasma arc. ### Claim 72 (depends on 61) The process of claim 61, wherein the arc means comprises an electric arc. ### Claim 73 (depends on 63) The process of claim 63, wherein the arc means comprises a plasma arc. ### Claim 74 (depends on 63) The process of claim 63, wherein the arc means comprises an electric arc. ### Claim 75 (depends on 22) The process of claim 22, wherein the arc means comprises a plasma arc.