Obtaining manganese pellets from manganese-containing technogenic waste

Abstract

Recycling manganese-rich industrial residues is a significant technological and environmental challenge in mining regions because it lowers long-term waste accumulation and provides a valuable supplementary feedstock for ferroalloy production. This study thoroughly examined fine-grained manganese sludge from the Ushkatyn-3 deposit (JSC «Zhayremsky GOK») using particle size analysis, X-ray fluorescence spectroscopy, X-ray diffraction, ICP-AES, and differential thermal analysis. Nearly all of the original technogenic material, which contained 15.0-18.3% Mn, was composed of barite, quartz, bixbyite, calcite, and braunite. Based on the identified granulometric and mineralogical properties, a gravity-magnetic beneficiation flowsheet was created. Sequential treatment using jigging, concentration tables, and high-intensity magnetic separation produced a finely dispersed manganese concentrate with a Mn content of 34.9-35.2% and a recovery of roughly 61%. Pelletizing mixtures containing calcium oxide, natural iron-bearing diatomite, and, in certain compositions, coke was made using the resultant concentrate. The formation of green pellets during granulation in an Eirich mixer-granulator has been examined in relation to binder content and particle-size distribution. The thermal behavior of the composite mixture was examined using TGA-DTA/DSC and quadrupole mass spectrometry, which revealed dehydration, carbonate breakdown, and polymorphic transformations of manganese phases over the temperature range of 200-1160°C. Because it offers adequate phase consolidation without partial melting, the sintering process proved that 1170°C is the optimal firing temperature. The formation of ferrobustamite (CaFe₂Si₂O₄), hausmannite (Mn₃O₄), and jacobsite (MnFe₂O₄) was verified by X-ray diffraction analysis of the fired pellets. This is the ferrosilicon calcium binding phase, which strengthens the agglomerates’ structural integrity. The sintered pellets’ high mechanical strength (up to 33.8 kg per pellet), apparent density of 1.45-1.91 g/cm³, and open porosity of 27-35% attest to their suitability as feedstock for ferromanganese alloy production. The developed beneficiation and agglomeration method represent an effective way to convert low-grade manganese sludge into useful metallurgical raw materials. The proposed technology reduces the environmental impact of tailings ponds and opens a viable path to the sustainable use of manganese-containing industrial waste.