Iron recovery from zinc mine tailings by magnetic separation followed by carbothermal reduction of self‐reducing briquettes

Abstract

The volume of tailings produced by the extractive industry has been increasing due to the processing of the low-grade ore. This issue can cause environmental accidents and require significant investment to control the disposal of tailings. Therefore, this study aims to recover iron from zinc mine tailings by wet magnetic separation followed by the carbothermal reduction of self-reducing briquettes. Two magnetic separation routes were investigated to concentrate iron. Zinc mine tailings were processed by route I, in a rougher stage followed by a scavenger stage; and route II, in a rougher stage followed by a cleaner stage. The carbothermal reductions were performed using self-reducing briquettes composed of Fe concentrate from the route with high Fe content and charcoal. The products were analyzed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), x-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), and volumetric chemical analysis. Magnetic separation route II provided the highest-grade Fe concentrate, 52% Fe, while route I provided 33% Fe. In the carbothermal reductions, a metallization degree of 98% in the Fe concentrate briquette, 97% in the briquette with a 10% replacement of its raw material by Fe concentrate, and 99% in the hematite briquette was reached. The replacement of raw material by Fe concentrate showed no significant change in Fe recovery. Considering the whole process, magnetic separation and carbothermal reduction, the recovery of Fe from the zinc mine tailings was 67%. Therefore, the process route suggested in this study will not only reduce tailings disposal and consequently the risk of environmental accidents, but it will also provide profitable raw material for the steel industry.

Optimization of magnetic separation of hematite contained in the depressed product from vazante mine s zinc ore flotation

“…A sample weighing approximately 20 kg was sent to the University of São Paulo's Mineral Processing and Waste Treatment Laboratory (LTM/USP). It should be noted that this is the same sample used by Vinhal et al [1] in their study. For this reason, no detailed mineralogical description was made herein as this material has already been described in detail in the cited reference.…”

“…The mining industry has seen a significant decline in mill feed grade in recent years, resulting in an ongoing build-up of materials not recovered at the mineral processing plants, whose economic value has not yet been determined [1,2]. Tailings dams have been the preferred method of disposal of such materials [3].…”

“…Part of the material contained in the Aroreira dam is reclaimed and fed into the processing plant to recover the remaining zinc content. Several studies on the recovery of different minerals from tailings dams have been conducted; their focus was the recovery of zinc [23], iron [1,24,25] and dolomite [26]. In view of the outlook for higher iron grades in the ROM material, an industrial magnetic concentration test unit has been in operation since 2021.…”

Metallurgical solid waste modified thermoplastic polyurethane composites: The thermal stability and combustion properties

“…Iron tailings are industrial solid waste with excess production in the metallurgical industry at present. As reported by the world steel industry, iron production increased from 1632.5 million tons in 2017 to 1712.1 million tons in 2018, and the production of iron tailings reached 476 million tons in 2018, accounting for 39.31% of the total tailings 7–9 . However, the current comprehensive utilization rate of iron tailings is less than 30%, and the massive accumulation of iron tailings not only occupies valuable land resources, but also triggers pollution of nearby soil and water bodies 10 .…”

Chemical Analysis of Hematite Ore Collected from Pokhari, Nawalparasi, Nepal

“…For instance, iron ores pellets are essential input materials in the manufacture of steel which can be reduced by reducing gas (a mixture of hydrogen and nitrogen gas) [ 17 ]. In the work of Jonathan et al, iron was separated from zinc mine tailings via wet magnetic separation followed by carbothermal reduction of self-reducing briquettes [ 18 ]. Jorge et al developed a self-reducing briquettes using biomass source such as charcoal, palm oil charcoal, eucalyptus bark charcoal, and basic oxygen furnace dust [ 19 ].…”