# US 9,435,005 B2 · Method for processing slags of non-ferrous metallurgy > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,005 B2 - Document ID: US9435005B2 - Status: Granted - Kind: B2 - Application number: 14/394,697 - Filed: 2013-04-15 - Published: 2015-05-07 - Granted: 2016-09-06 - Earliest claimed: 2012-04-16 - Assignees: Outotec (Finland) Oy - Applicants: Outotec (Finland) Oy - Inventors: Maija-Leena Metsarinta; Jussi Liipo; Pekka Kurki; Madeleine Scheidema - Web page: https://patentgrep.com/patent/US9435005B2 ## CPC - C22B 7/04: Working-up slag - C04B 5/00: Treatment of {metallurgical} slag (manufacture of slag wool C03B; in, or for, the production of metals C21B, C22B); Artificial stone from molten {metallurgical} slag {(other cast stone C04B32/005; mechanical aspects B28B1/54)} - C22B 4/00: Electrothermal treatment of ores or metallurgical products for obtaining metals or alloys (obtaining iron or steel C21B, C21C) - C22B 5/02: Dry methods {smelting of sulfides or formation of mattes} - Y02P 10/20: Recycling - C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A method for processing slags containing iron and non-ferrous metals, to produce clean slag free of detrimental substances and non-ferrous metals and suitable for use as a raw material or construction material. Slag is reduced in a reduction furnace with the help of reducing agents so that at least 5% of the iron of the slag is reduced into metal. Some of the non-ferrous metals, such as zinc, lead, arsenic and cadmium, vaporize. The contents of the reduction furnace are continuously mixed to prevent separation of a metallic phase from the slag. The generated slag-metal mixture is tapped off from the reduction furnace, cooled, crushed and ground to a finer size. Finally, a metal fraction is separated from a clean slag. ## Claims ### Claim 1 A method for processing slag containing iron and non-ferrous metals, the method comprising the steps of: feeding the slag into a reduction furnace; reducing the slag in the reduction furnace by means of a reducing agent to convert at least some of the non-ferrous metals to metallic form, where reduction occurs at least until 5 mass-% of the iron has reduced into metal and at least some of the non-ferrous metals has vaporized; mixing the contents of the reduction furnace during reduction to prevent settling of metal droplets from the slag; tapping a molten slag-metal mixture generated in the reduction furnace; cooling, crushing and grinding the slag-metal mixture; processing the slag-metal mixture to separate a metal fraction from a remaining clean slag, where the remaining clean slag is suitable as raw material in a useful process. ### Claim 2 (depends on 1) A method according to claim 1, wherein processing the slag-metal mixture comprises using at least one of the following methods: magnetic separation, gravitational separation, flotation, and screening. ### Claim 3 (depends on 2) A method according to claim 2, further comprising: feeding an exhaust gas from the reduction furnace to an oxidation process, where vaporized metals contained in the exhaust gas are oxidized to metal oxides; after the oxidation process, feeding the exhaust gas to a cleaning process, where metal oxides and other solids are separated from the gas; delivering the separated metal oxides to a further metallurgical process. ### Claim 4 (depends on 3) A method according to claim 3, wherein the cleaning process comprises at least one of scrubbing, using fabric filters, electric precipitation, and wet electric precipitation. ### Claim 5 (depends on 1) A method according to claim 1, further comprising: feeding an exhaust gas from the reduction furnace to an oxidation process, where vaporized metals contained in the exhaust gas are oxidized to metal oxides; after the oxidation process, feeding the exhaust gas to a cleaning process, where metal oxides and other solids are separated from the gas; delivering the separated metal oxides to a further metallurgical process. ### Claim 6 (depends on 5) A method according to claim 5, wherein the cleaning process comprises at least one of scrubbing, using fabric filters, electric precipitation, and wet electric precipitation. ### Claim 7 (depends on 1) A method according claim 1, wherein the reduction furnace is at least one of an alternating current (AC) electric furnace, a direct current (DC) electric furnace, a top submerged lance (TSL) furnace, a Kaldo furnace, and a settler of a suspension smelting furnace. ### Claim 8 (depends on 1) A method according to claim 1, wherein mixing of the contents of the reduction furnace comprises at least one of injection feeding of the reducing agent, feeding of the reducing agent through a hollow electrode, use of gaseous or gas generating reducing agents, feeding of inert gas through porous plugs mounted at the bottom of the furnace, and electromagnetic stirring. ### Claim 9 (depends on 1) A method according claim 1, wherein reduction in the reduction furnace reduces 5-30% of the iron of the slag into metallic iron. ### Claim 10 (depends on 1) A method according to claim 1, wherein the temperature in the reduction furnace is held between 1400° C. and 1500° C. during the reduction step. ### Claim 11 (depends on 10) The method according to claim 10, wherein the temperature in the reduction furnace is held at about 1450° C. during the reduction step. ### Claim 12 (depends on 1) The method according to claim 1, wherein the retention time in the reduction furnace is 0.5 hours to 2 hours. ### Claim 13 (depends on 1) The method according to claim 1 where the non-ferrous metals includes at least one of copper, nickel, zinc, lead, arsenic, and cadmium. ### Claim 14 (depends on 1) The method according to claim 1 where the non-ferrous metals converted in the reducing furnace to metallic form are different than the non-ferrous metals vaporized in the reducing furnace. ### Claim 15 (depends on 14) The method according to claim 14 where the non-ferrous metals converted in the reducing furnace to metallic form includes at least one of copper and nickel. ### Claim 16 (depends on 14) The method according to claim 14 where the non-ferrous metals vaporized in the reducing furnace includes at least one of zinc, lead, arsenic, and cadmium. ### Claim 17 (depends on 16) The method according to claim 16 where the non-ferrous metals converted in the reducing furnace to metallic form includes at least one of copper and nickel.