Journal of Mining and Metallurgy, Section B: Metallurgy

Gold recovery and migration mechanism in the copper smelting and converting

Shengli QU, Lin ZOU, Zhunqin DONG, Lei Li — Thu, 31 Jul 2025 00:00:00 +0200

The gold embedded in the copper concentrate is enriched in the matte phase during copper smelting and transferred into blister copper during subsequent processing, via which the gold was recycled. In the copper smelting, gold dissolved and appeared as Au (Ⅲ) in the formed gold-matte solid solution. This solid solution could be formed in two ways: by exchanging Au atoms for Cu atoms in the Cu5FeS4 (matte) crystal lattice and by doping Au atoms in Cu5FeS4. In the matte converting, the transfer of gold from the matte phase to blister copper occurred spontaneously due to a fact that the surface tension between the gold and matte phases was considerably higher than that between the gold and copper phases. Gold capture by blister copper occurred by Au atoms replacing Cu atoms in the Cu cell.

Studying the structure and properties of quasi high-entropy alloys of the Fe-Co-Cr-Ni-Mn-Nb system with Mo additives

Sv.S. Kvon, V.Yu. Kulikov, A.Z. Issagulov, Saniya Arinova, A.R. Abildina — Thu, 31 Jul 2025 00:00:00 +0200

The paper presents the results of studying the structure, hardness and wear resistance of quasi high-entropy alloys of the Fe-Co-Cr-Ni-Mn-Nb system with Mo additives. As a result of the study, it was shown that quasi high-entropy alloys of the Fe-Cr-Mn-Ni-Co-Nb system smelted with partial use of ferroalloys and additionally alloyed with Mo in the amount of 5-15% by weight, demonstrated very system alloys without Mo additives. The structure of the studied samples is represented by a mixture of solid solutions of Mn, Fe, Co, Ni of the face-centered cubic typе (FCC), Nb and Mo of the body centered cubic type (BCC), as well as interstitial phases: a carbide phase, a Laves phase and a σ-phase.

Effect of adsorption of surfactant mixtures on wettability of sintering dust

Jiantao Ju, Liule Wei, Qiang Bi, Yongwei Hu — Mon, 24 Nov 2025 12:42:02 +0100

In order to improve the wettability of sintering dust, we investigated the action mechanism of Triton X-100 (TX-100), which synergizes with Dodecyl Trimethyl Ammonium Bromide (DTAB). The settling times of nine different types of surfactants were measured, and the optimal ratio of cationic and nonionic surfactants to synergistically improve the wettability of sintering dust was determined from these measurements. The adsorption performance of the surfactants in the mixed solution and their effect on the wetting properties of sintering dust were investigated by sedimentation test, adsorption amount, Fourier transform infrared spectroscopy, and zeta potential determination. The results showed that a synergistic effect could be obtained when DTAB and TX-100 were mixed, and the DTAB: TX-100=2:2 composite solution with a concentration of 0.3% had a good wetting effect on the sintering dust. As the concentration of the surfactant mixtures increased, the content of hydrophilic functional groups and the absolute potential value of the surface of the sintering dust increased accordingly. Among them, DTAB was affected by alkyl interactions and had a greater adsorption affinity, and the hydrophobic tail of TX-100 was entangled with that of DTAB due to hydrophobic interactions and shared an adsorption site. This study contributes to the selection of surfactants for the efficient wetting of sintering dust and provides a theoretical basis for hydrometallurgy and dust control.

Microstructure changes in welded duplex stainless steel and their effects on hardness and corrosion resistance

Mon, 24 Nov 2025 12:44:33 +0100

Duplex stainless steel (DSS) is extensively employed in a range of applications because it contains equal proportions of the two phases, ferrite and austenite, as well as a specific percentage of alloying elements. These combined benefits provide the material with superior strength, corrosion resistance, and good welding capacity. During the welding process of DSS, equal amounts of both phases are disrupted, resulting in precipitation. To investigate this phenomenon, this study aims to analyze the effect of changes in welding current by adding 10% N₂ with Ar (as a shielding gas) on microstructure changes of DSS weldment. The changes were evaluated through the hardness and corrosion resistance. The study found that by increasing welding current, the Cr₂N precipitates disappear in the WZ, with a small amount appearing only in the HAZ. However, the very low welding current causes the formation of Cr₂N precipitates in both the WZ and HAZ. The results indicate a direct relationship between the volume fraction of austenite and the welding current. Reducing the welding current increases the hardness of DSS welds due to a higher ferrite volume fraction. Moreover, the corrosion resistance of DSS weldment improves with an increase in the welding current due to the increase in the amount of austenite phase.

Enhancing Corrosion Resistance and Structural Properties of Ni-TiO2 Composite Coatings: The Impact of SDS Surfactant

Mon, 24 Nov 2025 12:45:03 +0100

Ni-TiO₂ composite coatings are promising materials for enhancing the corrosion resistance and structural properties of steel substrates in various industrial applications. Corrosion remains a major issue for steel components, prompting the need for effective protective coatings. This study investigates the influence of sodium dodecyl sulfate (SDS) surfactant on the structural, electrochemical, mechanical, and morphological properties of Ni-TiO₂ composite coatings electrodeposited on BS2 steel. The coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), microhardness testing, and electrochemical techniques, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results show that SDS incorporation led to an increase in the crystallite size of the coatings, from 35.92 nm to 80.82 nm, and a significant enhancement in the relative texture coefficient (RTC) along the (200) plane (88.09%). SEM analysis revealed a more compact and uniform surface morphology, with SDS reducing surface porosity from 8.23 × 10^-3% to 2.20 × 10^-6%. Electrochemical measurements demonstrated a substantial improvement in corrosion resistance, with charge transfer resistance (R_ct) increasing from 5.17 kΩ.cm² to 312.65 kΩ.cm² and polarization resistance (R_p) rising from 2.5 kΩ.cm² to 176.38 kΩ.cm². The microhardness of the coatings decreased slightly from 256.26 kgf.mm^-2 to 217.22 kgf.mm⁻², indicating a trade-off between mechanical strength and enhanced corrosion protection. These findings highlight the potential of SDS as a valuable additive for optimizing Ni-TiO₂ composite coatings, although further research is needed to explore the impact of SDS concentration, long-term durability, and the performance of these coatings in more aggressive environments.

Microstructure and hardness of Bi-modified magnesium AZ31 alloys subjected to severe plastic deformation

Javad Yazdi, Mohammad Hassan Farshidi, Gholamreza Ebrahimi — Mon, 24 Nov 2025 12:45:20 +0100

Magnesium alloys are known as attractive materials because of their low density and good thermal conductivity. However, compared to competing metallic materials such as aluminum alloys, magnesium alloys have lower strength. Among different methods introduced for strengthening metallic materials, severe plastic deformation is notable for its efficiency and relative simplicity. This study investigates the effect of bismuth content on the microstructure evolution and hardness of magnesium AZ31 alloy subjected to severe plastic deformation through equal channel angular pressing. For this purpose, AZ31 alloys with nominal bismuth contents of 0%, 1%, and 3% were processed by up to four passes of equal channel angular pressing at 300 °C. The microstructure evolution of these alloys was then examined using optical and scanning electron microscopy. The hardness of the specimens was measured using the Vickers method. Results show that bismuth-enriched second-phase particles are fragmented during severe plastic deformation. Additionally, increasing the bismuth content leads to more rapid grain refinement during severe plastic deformation due to the pinning effect of these second-phase particles on the grain boundaries. Faster hardening rates during severe plastic deformation were observed for the bismuth-containing AZ31 alloys. This effect is attributed to the more rapid grain refinement and the increase in the Hall-Petch coefficient resulting from the presence of fine bismuth-enriched particles.

Constitutive analysis of Cu-DHP alloy during hot compression

Mon, 24 Nov 2025 12:45:35 +0100

The hot deformation behavior of the deoxidized high-phosphorus copper (Cu-DHP) was investigated during compressive deformation at a wide deformation temperature range of 200 to 1000 °C and strain rates ranging from 0.0005 to 0.4 s^-1. The flow curves related to the hot working regime (500 to 1000 °C) generally showed distinct peak stresses with the fall of flow stress after the peak point, revealing the occurrence of dynamic recrystallization (DRX). By increasing the Zener-Hollomon parameter, the cyclic flow curves were replaced by the single-peak ones, and finally by the characteristic dynamic recovery (DRV) curves. At temperatures lower than half of the melting point, only DRV-type curves were observed. Based on the constitutive analysis, the apparent activation energy of 274.1 kJ/mol, hyperbolic sine power of 4.88, and power law stress exponent of 5.27 were obtained, resulting in the flow stress equations to describe material flow in the hot working regime. The power law breakdown and the importance of deformation temperature were also critically discussed based on mathematical fitting, strain rate sensitivity index, and microstructural analysis.

Effect of reduction ratio on die fill-out and hardness profile of cold-drawn polygonal rods made of acid resistant steel X6CrNiTi18-10

Maciej Rumiński, Piotr Skubisz, Piotr Micek — Mon, 24 Nov 2025 12:45:48 +0100

The study investigates the effect of the reduction ratio on strain hardening efficiency and load during the drawing process of austenitic acid-resistant steel X6CrNiTi18-10. The focus is on optimizing geometry-related process conditions to achieve the highest quality and productivity when drawing special-purpose rods with polygonal shapes, specifically square and hexagonal cross-sections. The research addresses how increasing the reduction ratio can enhance strain hardening while reducing the number of drawing passes, ultimately affecting quality and load. Numerical modeling was used to analyze the relationship between strain hardening and load versus the reduction ratio. Proper models and assumptions were formulated and subsequently verified through experiments, which confirmed the validity of the mathematical and numerical models for load estimation. The study quantified the effect of strain on strength properties by mapping of measured hardness along the strain gradient. The application of variable billet diameters produced a similar hardness profiles for both analyzed rod geometries and reversed the effect on underfilling of the corners. The findings indicate a threshold reduction ratio for producing sound rods with square or hexagonal cross-sections. Exceeding this threshold can cause excessive strain hardening, leading to increased hardness that impedes corner fill-out and/or results in failure.

Optimizing calcium additions for a strength–corrosion resistance balance in squeeze-cast Zn–Al–Cu–Mg alloys

THIYAGESAN G, SankaraRaman Sankaranarayanan, S.P. Kumaresh Babu — Mon, 24 Nov 2025 12:46:18 +0100

In this study, squeeze-cast Zn–Al–Cu–Mg alloys with varying Ca additions (0, 0.5, 1.0, and 1.5 wt.%) were investigated to evaluate the combined effects of microstructural evolution on mechanical and corrosion performance. Microstructural analysis showed a transition from coarse Zn-rich dendrites in the base alloy to a refined and uniform morphology with Ca additions up to 1.0 wt.%, followed by coarsening and increased porosity at 1.5 wt.% Ca due to excessive intermetallic formation. Mechanical testing indicated that the alloy with 1.0 wt.% Ca had the highest hardness (141 HV0.1) and tensile strength (359 MPa), attributed to grain refinement and dispersion strengthening, though with reduced ductility due to intermetallic brittleness. Electrochemical corrosion tests in 3.5 wt.% NaCl solution showed that the corrosion rate decreased from the base alloy to 1.0 wt.% Ca, confirming enhanced corrosion resistance due to microstructural refinement and protective film formation. However, excessive Ca addition (1.5 wt.%) increased the corrosion rate to 0.8109 mpy due to coarse intermetallics and porosity, which promoted localized attack. The results highlight that optimal Ca addition (1.0 wt.%) achieves a balance between strength, hardness, and corrosion resistance, making Ca-modified Zn–Al–Cu–Mg alloys promising candidates for structural and functional applications.

Antimony obtaining by hydrometallurgy - Emphasis on recovery from leach solutions

Marinela Panayotova, Vladko Panayotov — Mon, 24 Nov 2025 12:46:04 +0100

Antimony (Sb) is listed as a critical raw material in both Europe and the USA. Pyrometallurgical and hydrometallurgical methods are used for its recovery from raw sources. Hydrometallurgy is considered a suitable technology when Sb sources are low-grade ores or technogenic waste. After a brief introduction to the Sb species present in pregnant leach solutions (PLS) obtained by using different leaching reagents, this paper presents various methods for recovering Sb from PLS produced in the leaching hydrometallurgical stage. The discussion covers antimony recovery by hydrolysis and conversion, selective precipitation, crystallization, electrowinning, replacement, liquid-liquid extraction and ion exchange. Factors affecting the effectiveness of these processes and the recent attempts to improve these technologies are presented. Finally, possible future research directions are outlined.