1
Yeonuk Choi, Peter Kondos, Mark Graham Aylmore, Jacques McMullen, Gus Van Weert: Thiosulfate generation in situ in precious metal recovery. Barrick Gold Corporation, Senniger Powers, August 11, 2009: US07572317 (2 worldwide citation)

Precious metal recovery by thiosulfate leaching where thiosulfate lixiviant is generated in situ employing elemental sulfur generated from partial oxidation of sulfidic precious metal-bearing feed and/or employing reactants from processing effluent.


2
Yeonuk Choi, Serge Payant, Joo Kim, Anna Maria Giove, Ramachandra Rao, James Andrew Finch: Production of zinc oxide from acid soluble ore using precipitation method. Noranda, Katten Muchin Zavis Rosenman, April 27, 2004: US06726889 (2 worldwide citation)

The present invention relates to an apparatus and a process for producing zinc oxide from an acid soluble zinc-bearing material. The process according to the present invention comprises the steps of leaching the zinc oxide material with sulphuric acid; precipitating iron and silica from the leach so ...


3
Yeonuk Choi, Qiankun Wang, John William Langhans Jr: Method for recovering precious metals and copper from leach solutions. BARRICK GOLD CORPORATION, Sheridan Ross P C, June 9, 2015: US09051625 (1 worldwide citation)

The present disclosure is directed to a process for recovering a precious metal from a pregnant leach solution using a resin extractant. The precious metal is eluted from the loaded resin using an eluant comprising trithionate. The barren resin is contacted with a sulfide, bisulfide, and/or polysulf ...


4
Daniel Hillier, Noelene Ahern, Yeonuk Choi: Process for mercury control during pressure oxidation. Barrick Gold Corporation, Sheridan Ross P C, April 5, 2011: US07918919 (1 worldwide citation)

A method for suppressing mercury dissolution during pressure oxidation of precious metal-containing materials in the presence of halogens and halides is provided. Pressure oxidation is performed under controlled oxidative conditions to maintain the mercury predominantly in the solid residue.


5
Yeonuk Choi, Peter Kondos, Jacques McMullen: Selective precipitation of metal sulfides. Barrick Gold Corporation, Senniger Powers, January 4, 2011: US07862786 (1 worldwide citation)

A method for recovering zinc ions by selective zinc sulfide precipitation from an aqueous solution comprising zinc ions and metal ions of a metal that precipitates as a metal sulfide at a pH lower than a pH at which zinc ions precipitate as a zinc sulfide.


6
Yeonuk Choi, Samir Chefai: Co-current and counter current resin-in-leach in gold leaching processes. Barrick Gold Corporation, Sheridan Ross P C, October 17, 2017: US09790572 (1 worldwide citation)

A method and system are provided in which a gold and/or silver-collecting resin-in-leach circuit comprises both co-current and counter-current sections.


7
Yeonuk Choi, Samir Chefai: Co-current and counter current resin-in-leach in gold leaching processes. Barrick Gold Corporation, Sheridan Ross PC, May 6, 2014: US08715389 (1 worldwide citation)

A method and system are provided in which a gold and/or silver-collecting resin-in-leach circuit comprises both co-current and counter-current sections.


8
Yeonuk Choi, Peter D Kondos, Jacques McMullen: Process for reduced alkali consumption in the recovery of silver. Barrick Gold Corporation, Sheridan Ross P C, August 28, 2012: US08252254

The present invention is directed to a precious metal recovery process in which basic ferric sulphates and/or jarosites are controlled by hot curing of the autoclave discharge slurry followed by decomposition of argentojarosite using strong acid consumers.


9
Yeonuk Choi, Ahmad Ghahremaninezhad Gharelar: Method for pre-treatment of gold-bearing oxide ores. Barrick Gold Corporation, Sheridan Ross P C, December 25, 2018: US10161016

The disclosure relates to pre-treatment of precious metal-bearing oxide ores, prior to precious metal leaching by thiosulfate. The process comprises mixing oxide ore in oxygenated water in the presence of a carbon-based material (e.g., activated carbon or other type of carbon). The carbon-based mate ...


10
Daniel Hillier, Yeonuk Choi, Noelene Ahern: Process for controlling acid in sulfide pressure oxidation processes. Barrick Gold Corporation, Sheridan Ross P C, September 11, 2012: US08262770

The present invention is directed to flotation of refractory gold sulfide ores and to pressure oxidized residue neutralization using flotation tailings that have been contacted with an off gas of pressure oxidation.