Effect of Sulfur Content in Sulfate-Rich Copper Tailings on the Properties of MgO-Activated Slag Materials

Abstract

The high-value utilization of sulfate-rich tailings (SRCTs) can accelerate their mass consumption, so the many problems caused by the massive accumulation of SRCTs can be alleviated, such as environmental pollution, land occupation, security risk, etc. This study proposes using SRCTs to replace fine natural aggregates in MgO-activated slag materials (MASMs) and investigate the influence of the sulfur content in SRCTs on the properties of MASMs. The experimental results showed that the 28 d compressive strength of MASM mortars was increased by up to 83% using SRCT composites. Two major mechanisms were discovered: additional hydration product formation and pore structure refinement. The results of XRD suggested that incorporating SRCT composite into MASMs increased the production of expansive sulfate-containing hydration products, such as ettringite, gypsum, and hydroxyl-Afm. The results of element mapping showed that the oxidation of pyrite in SRCTs could release sulfates into the surrounding area and participate in the hydration of MASM, indicating that SRCTs can work as an auxiliary activator for MASMs. Furthermore, the addition of SRCT significantly refined the pore structure of MASMs, leading to the reduction in porosity by up to 37.77%. These findings confirm a synergistic effect on activating the slag between SRCTs and MgO, promoting the mass utilization of SRCTs. As a result, the additional expansive hydration products contribute to the enhanced compressive strength and refined pore structure.

Effects of Pyrrhotite on the Combustion Behavior and the Kinetic Mechanism of Pyrite-Pyrrhotite Mixture Powders in the Air

“…Moreover, pyrite and pyrrhotite, as minerals associated with coal and chalcopyrite, are among the main sources of sulfur dioxide emissions during the combustion of coal and chalcopyrite leaching, which is a signifcant cause of environmental pollution [12][13][14]. Accidents caused by combustion and explosion, as well as pollution in iron sulfde mines, have resulted in signifcant damage and loss of life in several countries in the past decades [15,16]. Terefore, to address the challenges associated with the use of iron sulfde minerals, it is essential to study the phase transition behavior of iron sulfde combustion in an air atmosphere.…”