Methods for treating carbon materials including carbonaceous ores

Abstract

Methods described herein generally relate to the treatment of carbonaceous materials with ozone to facilitate the subsequent recovery of metal species (e.g., precious metals) from the carbonaceous material. In some cases, the method may involve exposure of a carbonaceous material to a relatively low amount of ozone. In some cases, the carbonaceous material may be subjected to oxidizing conditions, e.g. by autoclaving or bio-oxidation, prior to ozone treatment. Such embodiments may allow for more simplified and cost-effective methods for metal recovery.

What is claimed: 
     
         1 . A method, comprising:
 exposing a carbonaceous feed material comprising at least one metal species to oxidizing conditions selected to produce an oxidized carbonaceous material, wherein the preg-robbing index of the oxidized carbonaceous material is substantially the same as the preg-robbing index of the carbonaceous feed material; and   treating the oxidized carbonaceous material with ozone to produce an ozone-treated carbonaceous material, wherein the preg-robbing index of the ozone-treated carbonaceous material is lower than the preg-robbing index of the oxidized carbonaceous material.   
     
     
         2 . A method, comprising:
 exposing a carbonaceous feed material comprising a carbonaceous preg-robbing component and at least one metal species to oxidizing conditions selected to produce an oxidized carbonaceous material, wherein the amount of the carbonaceous preg-robbing component of the oxidized carbonaceous material is substantially the same as the amount of the carbonaceous preg-robbing component of the carbonaceous feed material; and   treating the oxidized carbonaceous material with ozone to produce an ozone-treated carbonaceous material, wherein the amount of the carbonaceous preg-robbing component of the ozone-treated carbonaceous material is lower than the amount of the carbonaceous preg-robbing component of the oxidized carbonaceous material.   
     
     
         3 . A method as in any preceding claim, further comprising:
 treating the ozone-treated carbonaceous material with a chemical reagent to recover the at least one metal species from the ozone-treated carbonaceous material.   
     
     
         4 . A method as in  claim 3 , wherein the chemical reagent comprises a cyanide species. 
     
     
         5 . A method as in any preceding claim, wherein the ozone-treated carbonaceous material is subjected to carbon-in-leach conditions to recover the at least one metal species from the ozone-treated carbonaceous material. 
     
     
         6 . A method as in any preceding claim, wherein the ozone-treated carbonaceous material is subjected to carbon-in-pulp conditions to recover the at least one metal species from the ozone-treated carbonaceous material. 
     
     
         7 . A method as in claim any preceding claim, wherein the carbonaceous material is a carbonaceous ore or carbonaceous ore concentrate. 
     
     
         8 . A method as in any preceding claim, wherein the carbonaceous material is a carbonaceous sulfide ore or carbonaceous ore concentrate. 
     
     
         9 . A method as in any preceding claim, wherein the at least one metal species is a precious metal. 
     
     
         10 . A method as in any preceding claim, wherein the at least one metal species is gold, silver, or copper. 
     
     
         11 . A method as in any preceding claim, wherein the at least one metal species is gold. 
     
     
         12 . A method as in any preceding claim, wherein about 70% or more of the at least one metal species is recovered. 
     
     
         13 . A method as in any preceding claim, wherein about 80% or more of the at least one metal species is recovered. 
     
     
         14 . A method as in any preceding claim, wherein about 90% or more of the at least one metal species is recovered. 
     
     
         15 . A method as in any preceding claim, wherein about 95% or more of the at least one metal species is recovered. 
     
     
         16 . A method as in any preceding claim, wherein, upon treatment with ozone, at least a portion of the carbonaceous preg-robbing component is chemically converted to a carboxylic acid species or an oxide species. 
     
     
         17 . A method as in any preceding claim, wherein the oxidized carbonaceous material is treated with ozone in a continuously stirred tank reactor, a fluidized bed reactor, a plug flow reactor, a pipe reactor, or a slurry bubble column reactor. 
     
     
         18 . A method as in any preceding claim, wherein the oxidized carbonaceous material is treated with ozone in a fluidized bed reactor. 
     
     
         19 . A method as in any preceding claim, wherein, prior to ozone treatment, the oxidized carbonaceous material has a preg-robbing index greater than 20, and, after treatment with ozone, has a preg-robbing index less than 20. 
     
     
         20 . A method as in any preceding claim, wherein the steps of treating and/or exposing are performed under ambient conditions. 
     
     
         21 . A method as in any preceding claim, wherein a slurry comprising the oxidized carbonaceous material is treated with the ozone. 
     
     
         22 . A method as in any preceding claim, wherein the slurry is maintained at a pH range of about 2 to about 10 during treatment with ozone. 
     
     
         23 . A method as in any preceding claim, wherein the slurry is maintained at a pH range of about 5 to about 8 during treatment with ozone. 
     
     
         24 . A method as in any preceding claim, wherein the slurry is maintained at a temperature between about 25° C. to about 150° C. during treatment with ozone. 
     
     
         25 . A method as in any preceding claim, wherein the temperature of the slurry is maintained during treatment with ozone without an external source of energy. 
     
     
         26 . A method as in any preceding claim, wherein the set of oxidizing conditions involves autoclaving or biooxidative leaching. 
     
     
         27 . A method as in any preceding claim, wherein oxygen produced during treatment of the oxidized carbonaceous material with ozone is recovered and/or used for autoclaving or biooxidative leaching of the carbonaceous feed material. 
     
     
         28 . A method as in any preceding claim, wherein the set of oxidizing conditions in the exposing step does not involve exposing the carbonaceous feed material to ozone. 
     
     
         29 . A method, comprising:
 treating a carbonaceous material comprising at least one metal species with about 0.10 grams of ozone per gram carbonaceous material or less to produce an ozone-treated carbonaceous material;   treating the ozone-treated carbonaceous material with a chemical reagent to recover the at least one metal species from the ozone-treated carbonaceous material.   
     
     
         30 . A method as in  claim 29 , wherein the carbonaceous material is a carbonaceous ore or carbonaceous ore concentrate. 
     
     
         31 . A method as in any preceding claim, wherein the carbonaceous material is a carbonaceous sulfide ore or carbonaceous ore concentrate. 
     
     
         32 . A method as in any preceding claim, wherein the at least one metal species is a precious metal. 
     
     
         33 . A method as in  claims 29 - 31 , wherein the at least one metal species is gold, silver, or copper. 
     
     
         34 . A method as in any preceding claim, wherein the at least one metal species is gold. 
     
     
         35 . A method as in any preceding claim, wherein about 70% or more of the at least one metal species is recovered. 
     
     
         36 . A method as in any preceding claim, wherein about 80% or more of the at least one metal species is recovered. 
     
     
         37 . A method as in any preceding claim, wherein about 90% or more of the at least one metal species is recovered. 
     
     
         38 . A method as in any preceding claim, wherein about 95% or more of the at least one metal species is recovered. 
     
     
         39 . A method as in any preceding claim, wherein the carbonaceous material comprises a carbonaceous preg-robbing component and, upon treatment with ozone, the amount of the carbonaceous preg-robbing component is decreased relative to the amount prior to treatment with ozone. 
     
     
         40 . A method as in any preceding claim, wherein, upon treatment with ozone, at least a portion of the carbonaceous preg-robbing component is chemically converted to a carboxylic acid species or an oxide species. 
     
     
         41 . A method as in any preceding claim, wherein the carbonaceous material is treated with ozone in a continuously stirred tank reactor, a fluidized bed reactor, a plug flow reactor, a pipe reactor, or a slurry bubble column reactor. 
     
     
         42 . A method as in any preceding claim, wherein the carbonaceous material is treated with ozone in a fluidized bed reactor. 
     
     
         43 . A method as in any preceding claim, wherein, prior to ozone treatment, the carbonaceous material has a preg-robbing index greater than 20, and, after treatment with ozone, has a preg-robbing index less than 20. 
     
     
         44 . A method as in any preceding claim, wherein the steps of treating and/or exposing are performed under ambient conditions. 
     
     
         45 . A method as in any preceding claim, wherein a slurry comprising the carbonaceous material is treated with ozone. 
     
     
         46 . A method as in any preceding claim, wherein the slurry is maintained at a pH range of about 2 to about 10 during treatment with ozone. 
     
     
         47 . A method as in any preceding claim, wherein the slurry is maintained at a pH range of about 5 to about 8 during treatment with ozone. 
     
     
         48 . A method as in any preceding claim, wherein the slurry is maintained at a temperature between about 25° C. to about 150° C. during treatment with ozone. 
     
     
         49 . A method as in any preceding claim, wherein the temperature of the slurry is maintained during treatment with ozone without an external source of energy. 
     
     
         50 . A method as in any preceding claim, wherein the chemical reagent comprises a cyanide species. 
     
     
         51 . A method as in any preceding claim, wherein the ozone-treated carbonaceous material is subjected to carbon-in-leach conditions to recover the at least one metal species from the ozone-treated carbonaceous material. 
     
     
         52 . A method as in any preceding claim, wherein the ozone-treated carbonaceous material is subjected to carbon-in-pulp conditions to recover the at least one metal species from the ozone-treated carbonaceous material. 
     
     
         53 . A method as in any preceding claim, wherein the carbonaceous material has been exposed to a set of oxidizing conditions prior to treatment with ozone. 
     
     
         54 . A method as in any preceding claim, wherein the set of oxidizing conditions involves autoclaving or biooxidative leaching. 
     
     
         55 . A method as in any preceding claim, wherein the set of oxidizing conditions does not include exposure to ozone. 
     
     
         56 . A method as in any preceding claim, wherein oxygen produced during treatment of the carbonaceous material with ozone is recovered and/or used for autoclaving or biooxidative leaching of the carbonaceous feed material.