Methods for controlling iron via magnetite formation in hydrometallurgical processes

Patent metadata

Field	Value
Publication number	US-10689732-B2
Application number	US-201716465856-A
Country	US
Kind code	B2
Filing date	Nov 30, 2017
Priority date	Dec 1, 2016
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

A method of controlling iron in a hydrometallurgical process is disclosed. The method may comprise the steps of: leaching ( 14, 114 ) a feed slurry ( 2, 102 ); forming a pregnant leach solution ( 12 a, 12 b; 112 a, 112 b ); removing a first leach residue ( 18, 118 ) from the pregnant leach solution ( 12 a, 12 b ); and sending a portion ( 12 b, 112 b ) of the pregnant leach solution ( 12 a, 12 b ) and/or raffinate ( 22, 122 ) produced therefrom, to an iron removal process ( 34, 134 ). According to some preferred embodiments, the iron removal process ( 34, 134 ) may comprise the steps of: sequentially processing the pregnant leach solution ( 12 a, 12 b ) and/or raffinate ( 22, 122 ) produced therefrom in a first reactor (R 1 ) a second reactor (R 2 ), and a third reactor (R 3 ); maintaining a pH level of the first reactor (R 1 ) above 4, by virtue of the addition of a first base; maintaining a pH level of the second (R 2 ) and/or third (R 3 ) reactors above 8.5, by virtue of a second base; and forming solids ( 46 ) comprising magnetite ( 68 ). The method may further comprise the steps of performing a solid liquid separation step ( 36 ) after the iron removal process ( 34, 134 ); and performing a magnetic separation step ( 64 ) to remove magnetite ( 68 ) from said solids comprising magnetite ( 68 ), without limitation. A system for performing the method is also disclosed.

First claim

The invention claimed is:

1. A method of controlling iron in a hydrometallurgical leach process ( 1 ) comprising the steps of:
leaching ( 14 , 114 ) a feed slurry ( 2 , 102 );
forming a pregnant leach solution ( 12 a , 12 b ; 112 a , 112 b );
removing a first leach residue ( 18 , 118 ) from the pregnant leach solution ( 12 a , 12 b ); and
sending a portion ( 12 b , 112 b ) of the pregnant leach solution ( 12 a , 12 b ) and/or raffinate ( 22 , 122 ) produced therefrom, to an iron removal process ( 34 , 134 ); wherein the iron removal process ( 34 , 134 ) comprises:
sequentially processing the pregnant leach solution ( 12 a , 12 b ) and/or raffinate ( 22 , 122 ) produced therefrom in a first reactor (R 1 ) a second reactor (R 2 ), and a third reactor (R 3 );
maintaining a pH level of the first reactor (R 1 ) in the range of 4-5, by virtue of an addition of a first base;
maintaining a pH level of the second (R 2 ) and/or third (R 3 ) reactors above 8.5, by virtue of an addition of a second base; and
forming solids ( 46 ) comprising magnetite ( 68 );

performing a solid liquid separation step ( 36 ) after the iron removal process ( 34 , 134 ); and
performing a magnetic separation step ( 64 ) to remove magnetite ( 68 ) from said solids comprising magnetite ( 68 ).

2. The method of claim 1 , further comprising a step of controlling the step of leaching ( 14 , 114 ) a feed slurry ( 2 , 102 ) such that the molar ratio of copper (Cu) to iron (Fe) is approximately 2:3.

3. The method of claim 1 , further comprising a step of adding oxygen to the first reactor (R 1 ).

4. The method of claim 3 , wherein the feed slurry ( 2 , 102 ) comprises a copper concentrate formed from chalcopyrite.

5. The method of claim 1 , further comprising a step of leaching ( 44 ) a first metal value from the solids ( 46 ) comprising magnetite ( 68 ) to remove a first metal value before the step of performing a magnetic separation step ( 64 ) to remove magnetite ( 68 ).

6. The method of claim 5 , wherein the first metal value comprises zinc, magnesium, and/or manganese.

7. The method of claim 5 , further comprising a step of leaching ( 54 ) a second metal value from the solids ( 46 ) comprising magnetite ( 68 ) to remove a second metal value before the step of performing a magnetic separation step ( 64 ) to remove magnetite ( 68 ), and after the step of leaching ( 44 ) a first metal value.

8. The method of claim 7 , wherein the first metal value comprises zinc, magnesium, and/or manganese in solution, and wherein the second metal value comprises copper in solution.

9. The method according to claim 8 , wherein the copper in solution is combined with a portion ( 12 a , 112 a ) of the pregnant leach solution ( 12 a , 12 b ; 112 a , 112 b ) entering a solvent extraction ( 24 , 124 ) system.

10. The method of claim 7 , wherein the step of leaching ( 44 ) a first metal value is performed at a pH level above 5, and wherein the step of leaching ( 54 ) a second metal value is performed at a pH level below 4 and above 0.5.

Assignees

• Smidth As F L

Inventors

• Chaiko David John
• Baczek Frank
• Rocks Sara (Sally)

Classifications

• Y02P10/20

  Recycling · CPC title

• C22B15/0089 Primary

  by chemical methods · CPC title

• C22B23/0415

  with acids or salt solutions except ammonium salts solutions · CPC title

• C22B23/0461

  by chemical methods · CPC title

• C22B15/0067

  with acids or salts thereof · CPC title