US 11,732,325 B2
Acid balance in a chloride heap leach
Damaso Barrios Ormeno, Antofagasta (CL); Clement Chilowa Chibwana, Antofagasta (CL); Johannes Mattheus Strauss, Antofagasta (CL); and Gary Vernon Rorke, Christchurch (NZ)
Assigned to BHP Chile Inc, Santiago (CL)
Appl. No. 16/955,936
Filed by BHP CHILE INC, Santiago (CL)
PCT Filed Dec. 20, 2018, PCT No. PCT/IB2018/060418
§ 371(c)(1), (2) Date Jun. 19, 2020,
PCT Pub. No. WO2019/123362, PCT Pub. Date Jun. 27, 2019.
Claims priority of application No. 2017/08731 (ZA), filed on Dec. 21, 2017; and application No. 2018/00345 (ZA), filed on Jan. 18, 2018.
Prior Publication US 2021/0207245 A1, Jul. 8, 2021
Int. Cl. C22B 15/00 (2006.01)
CPC C22B 15/0084 (2013.01) [C22B 15/0008 (2013.01); C22B 15/0069 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method of controlling acid balance in a high chloride heap leach process carried out at ambient temperature, wherein a chloride concentration is between 100 g/L and 180 g/L to ensure that copper dissolution in an agglomeration stage is not limited by acid to maximize the copper dissolution in a cure phase and thereby increase an overall copper recovery, wherein the method comprises:
an agglomeration stage in which acid and process solutions are combined with an ore prior to stacking to form a heap;
an aerated, but non-irrigated, cure phase to leach a portion of copper in the ore in the heap, wherein the copper dissolution in the aerated, but non-irrigated, cure phase is at least 30% by mass; and
an irrigated leach phase during which remaining copper minerals are leached and copper is recovered from a pregnant leach solution by a solvent extraction process followed by an electrowinning process, and
wherein the heap comprises a plurality of heap sections in which excess acid in the irrigated leach phase is reduced by circulating leach-liquor to the plurality of heap sections counter-current to the ore loading onto the plurality of heap sections and removal of ore from the plurality of heap sections, thereby increasing acid consumption by gangue mineral dissolution in proportion to a number of the plurality of heap sections irrigated during the irrigated leach phase and acid concentration in the pregnant leach solution, which reports to the solvent extraction process, is less than 10 g/L, to allow effective copper recovery from the pregnant leach solution in the solvent extraction process.