Methodology for non-waste recycling of dump nickel slags

The structure and chemical analysis on the structural components of dump converter nickel slags is given on the example slags received from South Ural Nickel Plant OJSC (SUNP) and Rezhsky Nickel Plant (RNP), as well as the chemical process in the reaction container during chemical-thermal treatment using special computer programs, the chemical composition and corrosion resistance of the obtained nickel coat are studied. Presently, slag dumps are exploited for extracting useful elements. The waste slag heap is moved from place to place, mixed, and as a result of crushing and separation, the content of 10 mm fractions in the dumps increases, which greatly complicates further processing. The waste slag was crushed to 0.16 mm fractions to maximize the opening of sulfide inclusions, while the magnetic separation was carried out to obtain magnetic and non-magnetic concentrates. Laboratory-based experiments on high-temperature treatment were carried out using Tamman furnace preheated to 1550-16000 °C. A test charge of dump slag concentrates in a graphite crucible was placed inside and kept at above temperature for 10-15 minutes. As the slag was separated from the metal, metallographic studies were carried out, so the yield ratio and chemical composition of the smelting products were determined. Maps of the element distribution in slag are given. The studies were carried out using a Jeol78M-7001F scanning electron microscope and an Oxford INCA x-mail 80 energy-dispersive spectrometer mounted on it. A Rigaku Ultima IV X-ray diffractometer was used to determine the phase composition. A process flow sheet is being developed for one of the non-waste recycling options for mature and newly formed dump nickel slags. The products of such recycling are metal alloyed with nickel, molybdenum, cobalt, as well as the slag utilisation products i.e. casting, crushed rock, cement additive, etc.