Research of application of magnetic separation method for purifying of low-nickel pyrrhotite and its combinations with flotation concentration

The Talnakh Concentrator (TC) processes the charge of rich, cuprous and disseminated ores of the Talnakh and Oktyabrskoye deposits using the collective-selective technology. The predominant mineral in the charge of ores fed to the TC is pyrrhotite. Co-extraction of pyrrhotite into finished copper and nickel-pyrrhotite concentrates leads to an increase in the volume of sulfur dioxide emissions during their further pyrometallurgical processing. Since 2016, the TC has implemented a beneficiation technology that provides for the maximum output of low-nickel pyrrhotite (hereinafter referred to as LNP) into the waste product (the extraction of pyrrhotite into tailings reached 65%). Since 2018, additional beneficiation of the low-nickel pyrrhotite product has been carried out to obtain a reflotation concentrate with a nickel content 2 times higher than the original one (1.0–1.2%), which allows for the extraction of about 20% of pyrrhotite from the operation (~7% of the original ore raw material) and associated isomorphically included platinum group metals, as well as the valuable mineral pentlandite (containing 30–35% nickel), presented in the form of micron flame-shaped inclusions in pyrrhotite grains. At the same time, X-ray phase analysis revealed that a significant part of the pyrrhotite is represented by a monoclinic modification, which created the prerequisites for research into the use of magnetic purification methods for lownickel pyrrhotite and its combinations with flotation concentration. The results of laboratory studies have determined that the most optimal option is the use of magnetic separation on the tailings of the LNP reflotation – the highest efficiency of beneficiation for nickel and the sum of PGMs was achieved: 21.90 and 23.77% against the option of using only flotation additional beneficiation of LNP: 15.12 and 18.42%, respectively.