Copper–cobalt　sulfide　flotation　concentrate　received　from　Comika　Mining　Kamoya　project　in　Congo　contains　around　24.2%　copper,　7.1%　cobalt,　22.9%　sulfur,　13%　iron,　and　a　small　amount　of　other　metals.　Under　the　condition　of　temperature　190 °C,　oxygen　partial　pressure　6 atm,　leaching　time　2 h,　liquid-to-solid　ratio　5:1,　and　initial　acidity　0 g/L,　metal　recovery　rates　of　over　98%　can　be　achieved　for　both　copper　and　cobalt.　Copper　that　exists　in　chalcocite,　bornite,　chalcopyrite,　and　carrollite　was　almost　completely　leached,　while　most　of　copper　in　limonite　remains　in　the　residue.　Cobalt　that　exists　in　carrollite　can　be　completely　leached,　while　the　unleached　cobalt　remains　in　the　pyrite　and　limonite　phases.　During　pressure　leaching,　sulfur　was　oxidized　into　sulfate.　Meanwhile,　iron　undergoes　a　dissolution　reaction　and　generates　high-valent　iron　ions,　which　can　be　partially　oxidized　into　metal　sulfides　and　partially　precipitated　under　low　acidity　conditions.　The　hematite　encapsulation　is　the　main　reason　for　the　incomplete　leaching　of　copper　and　cobalt.　©　2023,　Institute　of　Chemistry,　Slovak　Academy　of　Sciences.