REMOVAL OF CYANIDE FROM AQUEOUS STREAMS
First Claim
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1. A method for removing cyanide from an aqueous stream, wherein:
- the aqueous stream is contacted with carbon under conditions wherein the Eh (oxygen reduction potential (ORP) measured in mV) of the aqueous stream is 0 or above, to remove cyanide from the stream;
orthe aqueous stream is treated to control the Eh to 0 or above, and thereafter the aqueous stream is contacted with carbon, to remove cyanide from the stream.
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Abstract
This invention relates to a method of removing cyanide in the form of free cyanide (cyanide ions i.e. CN′) and weak acid dissociable cyanide (WAD) from an aqueous stream. WAD is cyanide complexed with metals such as Cu. The method finds particular application in removing cyanide from a tail stream from a carbon in leach (CIL) mining operation. The method of the invention is carried out by contacting an aqueous stream containing cyanide with carbon, under conditions wherein the Eh (oxygen reduction potential (ORP) measured in mV) of the aqueous stream is O or above. Advantageously the pH of the solution is buffered to from 7-9.
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Citations
63 Claims
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1. A method for removing cyanide from an aqueous stream, wherein:
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the aqueous stream is contacted with carbon under conditions wherein the Eh (oxygen reduction potential (ORP) measured in mV) of the aqueous stream is 0 or above, to remove cyanide from the stream;
orthe aqueous stream is treated to control the Eh to 0 or above, and thereafter the aqueous stream is contacted with carbon, to remove cyanide from the stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 48, 49, 50, 55, 56, 57, 59, 60, 61, 62, 63)
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33-47. -47. (canceled)
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51. A method for treating an aqueous stream containing metal values comprising the following the steps:
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treating the stream in a pre-oxidation stage; and subjecting the stream to a CIL process; wherein the pre-oxidation stage is conducted under conditions to provide an Eh (oxygen reduction potential (ORP) measured in mV) of the aqueous stream in the CIL process of 0 or above. - View Dependent Claims (52, 53, 54, 58)
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Specification