# US 8,465,723 B2 · Arsenic-containing solid and method for producing it > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,465,723 B2 - Document ID: US8465723B2 - Status: Granted - Kind: B2 - Application number: 12/531,132 - Filed: 2008-03-13 - Published: 2010-02-25 - Granted: 2013-06-18 - Earliest claimed: 2007-03-15 - Assignees: Dowa Metals & Mining Co., Ltd. - Applicants: Tetsuo Fujita; Ryoichi Taguchi; Hisashi Kubo - Inventors: Tetsuo Fujita; Ryoichi Taguchi; Hisashi Kubo - Web page: https://patentgrep.com/patent/US8465723B2 ## CPC - C01G 49/0018: {Mixed oxides or hydroxides, (C01G49/0009 takes precedence)} - C01G 28/02: Arsenates; Arsenites {(C01G28/001 takes precedence)} - C01G 49/02: Oxides; Hydroxides {(C01G49/0018 takes precedence)} - C01G 49/06: Ferric oxide [Fe2O3] - C22B 3/20: Treatment or purification of solutions, e.g. obtained by leaching (C22B3/18 takes precedence) - C22B 3/44: by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42) - C22B 7/006: {Wet processes} - C22B 30/04: Obtaining arsenic {(extraction of metal compounds by leaching in organic solutions C22B3/16; treatment or purification of solutions by adsorption on solids C22B3/24, by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42)} - C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer - C01P 2006/12: Surface area - Y02P 10/20: Recycling - C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20) - C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS - C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract Provided is an arsenic-containing solid comprising 100 parts by mass of a scorodite-type iron-arsenic compound and at least 1 part by mass of an iron oxide compound added thereto, in which the scorodite-type iron-arsenic compound is produced by adding an oxidizing agent to an aqueous acidic solution that contains a 5-valent arsenic (V) ion and a 2-valent iron (II) ion, then promoting the precipitation of an iron-arsenic compound with stirring the liquid, and finishing the precipitation thereof within a range where the pH of the liquid is at most 1.2. The iron oxide compound includes goethite, hematite and their mixture, preferably having a BET specific surface area of at least 3 m2/g, more preferably at least 20 m2/g. ## Claims ### Claim 1 An arsenic-containing solid comprising 100 parts by mass of a scorodite-type iron-arsenic compound and at least 0.5 parts by mass of an iron oxide compound added thereto. ### Claim 2 (depends on 1) The arsenic-containing solid according to claim 1, wherein the iron oxide compound has a BET specific surface area of at least 20 m2/g. ### Claim 3 (depends on 1) The arsenic-containing solid according to claim 1, wherein the iron oxide compound has a BET specific surface area of at least 3 m2/g and is added to the scorodite-type iron-arsenic compound in an amount of at least 5 parts by mass. ### Claim 4 (depends on 1) The arsenic-containing solid as claimed in claim 1, wherein the scorodite-type iron-arsenic compound is produced by adding an oxidizing agent to an aqueous acidic solution that contains a 5-valent arsenic (V) ion and a 2-valent iron (II) ion, then promoting the precipitation of an iron-arsenic compound with stirring the liquid, and finishing the precipitation thereof within a range where the pH of the liquid is at most 1.2. ### Claim 5 (depends on 1) The arsenic-containing solid as claimed in claim 1, wherein the iron oxide compound is at least one of iron on/hydroxide (FeOOH) and diiron trioxide (Fe2O3). ### Claim 6 (depends on 1) A method for producing an arsenic-containing solid of claim 1, comprising using a scorodite-type iron-arsenic compound having been processed in at least one solid-liquid separation step after its synthesis, preparing a slurry or a wet cake where the scorodite-type iron-arsenic compound particles and iron oxide compound particles coexist together, and collecting the solid fraction that constitutes the slurry or the wet cake. ### Claim 7 (depends on 2) The arsenic-containing solid as claimed in claim 2, wherein the scorodite-type iron-arsenic compound is produced by adding an oxidizing agent to an aqueous acidic solution that contains a 5-valent arsenic (V) ion and a 2-valent iron (II) ion, then promoting the precipitation of an iron-arsenic compound with stirring the liquid, and finishing the precipitation thereof within a range where the pH of the liquid is at most 1.2. ### Claim 8 (depends on 3) The arsenic-containing solid as claimed in claim 3, wherein the scorodite-type iron-arsenic compound is produced by adding an oxidizing agent to an aqueous acidic solution that contains a 5-valent arsenic (V) ion and a 2-valent iron (II) ion, then promoting the precipitation of an iron-arsenic compound with stirring the liquid, and finishing the precipitation thereof within a range where the pH of the liquid is at most 1.2. ### Claim 9 (depends on 2) The arsenic-containing solid as claimed in claim 2, wherein the iron oxide compound is at least one of iron oxyhydroxide (FeOOH) and diiron trioxide (Fe2O3). ### Claim 10 (depends on 3) The arsenic-containing solid as claimed in claim 3, wherein the iron oxide compound is at least one of iron oxyhydroxide (FeOOH) and diiron trioxide (Fe2O3). ### Claim 11 (depends on 4) The arsenic-containing solid as claimed in claim 4, wherein the iron oxide compound is at least one of iron oxyhydroxide (FeOOH) and diiron trioxide (Fe2O3). ### Claim 12 (depends on 2) A method for producing an arsenic-containing solid of claim 2, comprising using a scorodite-type iron-arsenic compound having been processed in at least one solid-liquid separation step after its synthesis, preparing a slurry or a wet cake where the scorodite-type iron-arsenic compound particles and iron oxide compound particles coexist together, and collecting the solid fraction that constitutes the slurry or the wet cake. ### Claim 13 (depends on 3) A method for producing an arsenic-containing solid of claim 3, comprising using a scorodite-type iron-arsenic compound having been processed in at least one solid-liquid separation step after its synthesis, preparing a slurry or a wet cake where the scorodite-type iron-arsenic compound particles and iron oxide compound particles coexist together, and collecting the solid fraction that constitutes the slurry or the wet cake. ### Claim 14 (depends on 4) A method for producing an arsenic-containing solid of claim 4, comprising using a scorodite-type iron-arsenic compound having been processed in at least one solid-liquid separation step after its synthesis, preparing a slurry or a wet cake where the scorodite-type iron-arsenic compound particles and iron oxide compound particles coexist together, and collecting the solid fraction that constitutes the slurry or the wet cake. ### Claim 15 (depends on 5) A method for producing an arsenic-containing solid of claim 5, comprising using a scorodite-type iron-arsenic compound having been processed in at least one solid-liquid separation step after its synthesis, preparing a slurry or a wet cake where the scorodite-type iron-arsenic compound particles and iron oxide compound particles coexist together, and collecting the solid fraction that constitutes the slurry or the wet cake.