# US 8,771,619 B2 · Method for treating arsenic containing materials > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,619 B2 - Document ID: US8771619B2 - Status: Granted - Kind: B2 - Application number: 13/880,347 - Filed: 2011-10-19 - Published: 2014-01-16 - Granted: 2014-07-08 - Earliest claimed: 2010-10-20 - Assignees: Xstrata Queensland Limited - Applicants: David Nakon; David Michael Way - Inventors: David Nakon; David Michael Way - Web page: https://patentgrep.com/patent/US8771619B2 ## CPC - C22B 3/12: in inorganic alkaline solutions - C22B 3/44: by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42) - 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)} - Y02P 10/20: Recycling - C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A method for selectively removing arsenic from a sulphide material containing arsenic by conducting a leaching step that includes contacting the material with a leaching solution that leaches arsenic from the material to form a pregnant liquor containing dissolved arsenic and a solid of a sulphide material of reduced arsenic content, and subsequently separating the solid from the pregnant liquor. The fresh leaching solution that is provided to the leaching step is an alkaline solution having a sulphide-containing compound present in an amount of from 0 to 1.0 times the amount of sulphur containing compound required to react with the arsenic present in the material. ## Claims ### Claim 1 A method for selectively removing arsenic from a sulphide material containing arsenic, the method comprising the steps of conducting a leaching step comprising contacting the material with a leaching solution that leaches arsenic from the material to form a pregnant liquor containing dissolved arsenic and a solid comprising a sulphide material of reduced arsenic content, and subsequently separating the solid from the pregnant liquor, wherein a leaching solution that is provided to the leaching step comprises an alkaline solution having a sulphide-containing compound present in an amount that is less than the stoichiometric amount of sulphur containing compound required to react with the arsenic present in the material. ### Claim 2 (depends on 1) A method as claimed in claim 1 wherein a recycle solution is provided to the leaching step. ### Claim 3 (depends on 2) A method as claimed in claim 2 wherein the recycle solution has a sulphide-containing compound present in an amount less than the stoichiometric amount of sulphur containing compound required to react with the arsenic present in the material. ### Claim 4 (depends on 2) A method as claimed in claim 2 wherein the amount of sulphide containing compounds present in the recycle solution results in a molar ratio of S2−/As of 0 to less than 1.5 being obtained. ### Claim 5 (depends on 1) A method as claimed in claim 1 wherein the leach solution contains no sulphide compounds. ### Claim 6 (depends on 1) A method as claimed in claim 1 wherein the leaching solution provided to the contacting step has at least 8 moles of alkaline material (calculated as equivalent OH—) for each mole of As present. ### Claim 7 (depends on 1) A method as claimed in claim 1 wherein the leaching solution includes sodium hydroxide present in a concentration of from 1.75 moles to 6.25 moles per liter. ### Claim 8 (depends on 1) A method as claimed in claim 1 wherein the leaching step is conducted at a temperature of from 30° C. up to the boiling point of the solution or slurry and a slurry of solid material and leaching solution formed in the leaching step has a solid content in the range of 5 to 90% w/w. ### Claim 9 (depends on 8) A method as claimed in claim 8 wherein the leaching step is conducted at a pressure above atmospheric pressure and the temperature utilised in the leaching step is above 100° C. ### Claim 10 (depends on 1) A method as claimed in claim 1 wherein the sulphide material containing arsenic also contains antimony and the method reduces the level of both arsenic and antimony. ### Claim 11 (depends on 1) A method as claimed in claim 1 wherein the leaching step comprises an open circuit leaching process, or the leaching step comprises a leaching circuit that includes leach solution recycling. ### Claim 12 A method for selectively removing arsenic from a sulphide material containing arsenic, the method comprising the steps of conducting a leaching step comprising contacting the material with a leaching solution that leaches arsenic from the material to form a leach solution containing dissolved arsenic and a solid comprising a sulphide material of reduced arsenic content, the leaching solution that is provided to the leaching step comprising an alkaline solution having a sulphide-containing compound present in an amount that is less than the stoichiometric amount of sulphur containing compound required to react with the arsenic present in the material, separating the solid from the pregnant liquor, and recycling at least part of the leach solution to the leaching step. ### Claim 13 (depends on 12) A method as claimed in claim 12 wherein the leach solution that is recycled to the leaching step contains one or more dissolved sulphide-containing compounds. ### Claim 14 (depends on 13) A method as claimed in claim 13 wherein the one or more dissolved sulphide-containing compounds are present in the leach solution that is recycled to the leaching step in an amount less than the stoichiometric amount of sulphur containing compound required to react with the arsenic present in the material. ### Claim 15 (depends on 12) A method as claimed in claim 12 wherein the leaching solution that is fed to the leaching step contains no sulphide containing compounds. ### Claim 16 (depends on 13) A method as claimed in claim 13 wherein the solid material contains antimony and the method also removes antimony from the solid material. ### Claim 17 A method for selectively removing antimony from a sulphide material containing antimony, the method comprising the steps of conducting a leaching step comprising contacting the material with a leaching solution that leaches antimony from the material to form a pregnant liquor containing dissolved antimony and a solid comprising a sulphide material of reduced antimony content, and subsequently separating the solid from the pregnant liquor, wherein a leaching solution that is provided to the leaching step comprises an alkaline solution having a sulphide-containing compound present in an amount less than the stoichiometric amount of sulphur containing compound required to react with the antimony present in the material. ### Claim 18 (depends on 17) The method of claim 17, wherein the leaching solution is a leaching solution which after contacting the material forms a pregnant liquor that includes the leach solution, and the method further comprises separating solids from the pregnant liquor and recycling at least part of the leach solution to the leaching step. ### Claim 19 (depends on 18) The method of claim 18, wherein at least 30 to 80% of the leach solution is recycled to the leaching step.