Journal of Mining and Metallurgy, Section B: Metallurgy

Sb recovery from an As pre-removed lead anode slime using a ZnS-Na2CO3 smelting reduction

2024-12-05T20:33:33+01:00

The lead anode slime is extensively produced in a lead electrolysis process, in which the Sb content was high to 10-50 wt% and well worth to be recycled. However, in its general alkaline pressure leaching for the As pre-removal, Sb was partially changed to Na₃SbO₄ with a high stability. It limited the Sb deep reduction and recovery in the followed Na₂CO₃ smelting reduction. Considering this, ZnS was creatively used as additive to destroy the stable structure of Na₃SbO₄ and increase the Sb reduction in this research, and meanwhile ZnS was reduced to a volatile Zn (g) and recycled. In a certain range, the increase of coke and ZnS amounts increased the Sb yield, and the Pb recycling could be accelerated. However, as an excessive ZnS added, the Sb compounds could be sulfurized and then combined with the generated PbS and Na₂S, producing a sodium matte of Na-Pb-Sb-S. It limited the Sb reduction and decreased the Sb yield. At the optimal condition of coke amount of 13%, ZnS amount of 8%, smelting temperature of 1200 °C and holding time of 90 min, the Sb, Pb and Zn yields achieved up to 97.6%, 95.9% and 98.9% respectively.

Numerical simulation of the casting process of an AZ91D magnesium alloy under a rotating-pulsed combined electromagnetic field

2024-12-05T20:33:33+01:00

Taking an AZ91D magnesium alloy as the research object, a three-dimensional (3D) numerical model was established and simulated by simulation analysis software. The effects of a rotating electromagnetic field (REMF), a pulsed electromagnetic field (PEMF) and a rotating pulsed electromagnetic field (R-PEMF) on the magnetic field and flow field of a metal melt were studied. The simulation results show that a rotational force is generated on the cross section of the melt during the REMF treatment, and the PEMF causes magnetic pressure on the cross section of the melt. Under the combined action of the two, the Lorentz force parallel to the melt axis increases, and a secondary flow pointing to the core of the melt is generated, which helps to homogenize the melt. By analyzing the solidification structure and elemental distribution of the metal, it was shown that R-PEMF effectively improved the solidification structure and macrosegregation of the Al in the AZ91D magnesium alloy.

Pyrometallurgical treatment of jarosite residue with a mixture of CaO, SiO2, and CaSi

2024-12-05T20:33:33+01:00

During the electrolytical production of zinc, iron in solutions is mainly controlled by the precipitation of jarosite. This precipitate also contains valuable metals (Zn, Pb, Cu, Ag) and toxic elements (Hg, Cd, As). This study deals with the pyrometallurgical treatment of jarosite waste to recover metal values and convert the waste into environmentally acceptable slag. Initially, the sample was heated to 100 °C to remove moisture, then roasted at 700 °C to release some OH‒ and sulfate groups by thermal decomposition. The analysis of the ternary diagram SiO2-CaO-Fe2O3 phase diagram showed that a flux with 48% CaO and 52% SiO2 can be used to melt the roasted jarosite at 1400 °C. Subsequently, tests were carried out with the reducing agent (CaSi), resulting in a mixture of slag and two metallic phases, one a Fe-Si alloy and the other a Pb-rich phase with the valuable metal Ag. Both the metallic and slag phases were characterised by chemical analysis, SEM-EDS and XRD. Additionally, the raw jarosite residue and the final slag were leached with an aqueous acetic acid solution to estimate their chemical stability. The obtained results show that the slag produced after the reduction of jarosite residue meets the environmental specifications and could be used as raw material in other industries.

A green approach to recovering lithium and cobalt from spent lithium-ion batteries using dilute HCl solution mixed with H. sabdariffa flower extract as a leaching agent

2024-12-05T20:33:34+01:00

Studies on the recovery of lithium and cobalt from spent lithium-ion batteries have attracted much in recent years. For a sustainable battery industry, processes for the recycling of valuable metals from spent batteries via a "green" approach have been constantly being improved and developed. In this work, an effective process for the recycling of lithium and cobalt from used lithium batteries of mobile phones using HCl solution at low concentrations combined with H. sabdariffa flower extract was studied. The effect of parameters like concentration of the extract and HCl, pulp density, reaction temperature, and time on the leaching percentage of metals was investigated. In these leaching systems, the extract containing organic compounds acts as complexing and reductive agents for dissolved metals. Optimum conditions for the leaching of these metals were 90% (v/v) of the extract, 0.5 mol/L HCl, 10 g/L pulp density, 90^oC, and 2.0 hours and 100% Li(I) and 91.3% Co(II) were leached under the optimum leaching conditions. Li(I) and Co(II) from leachate were fully separated by using AG®50W-X4 resins and the presence of the extract in the leaching solution trivially affected the recovery capacity of these metals. The metal loading capacity of the resin was determined to be 37.4 mg/g Co(II) and 1.2 mg/g Li(I). Thus, the use of plant extracts like H. sabdariffa flower can be considered a promising agent for the recovery of valuable metals from spent batteries.

Purification of amorphous boron powder by using the soluble transformation of acid-insoluble boron magnesium compounds

2024-12-05T20:33:34+01:00

At present, amorphous boron powder is considered to be the best fuel for solid fuel-rich propellants due to its extremely high volume calorific value and mass calorific value. Amorphous boron powder produced by magnesium thermal reduction contains many impurities that are insoluble in acids. In addition to impurities, oversized particles, and limited chemical reactivity, these issues significantly restrict the extensive use of this material in military and aerospace sectors. In this paper, the soluble transformation mechanism of insoluble boron magnesium compounds in amorphous boron powder at calcining and a method to purify boron powder were studied. To remove insoluble boron magnesium compounds in amorphous boron powder, insoluble impurities Mg₂B₂O₅ and MgB₄ were directionally transformed into soluble MgB₄O₇ and MgO at calcining. The samples were subsequently subjected to water or acid leaching to convert the crude amorphous boron powder product to high purity. SEM-EDS, XRD, XPS, and other techniques were used to determine the occurrence states of impurity phases. The transformation of impurity phases after calcining water leaching and acid leaching was monitored. The results showed that the magnesium content in the amorphous boron powder was reduced to 0.96%, and the purity of boron powder was increased to 97.34%.

Effect of chromium and titanium on the microstructure and mechanical properties of cast steel

2024-12-05T20:33:34+01:00

In this work, the influence of chromium and titanium on the microstructure and mechanical properties of cast steel is investigated. The analysis was carried out on a material covered by patent Pat.243157. Advanced techniques were used, including dilatometric analysis, light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The material was examined in various states: as-cast, quenched, and quenched with subsequent tempering at 200 °C, 400 °C, and 600 °C. Important mechanical properties such as hardness, yield strength, percentage elongation, percentage reduction in area after fracture, and impact toughness at temperatures ranging from -40 °C to +20 °C were evaluated. The results were compared with those of a reference cast steel without these alloying elements, allowing a detailed assessment of the influence of chromium and titanium. The investigation begins with a comprehensive literature review of the effects of these elements in iron-based alloys. The results highlight the influence of chromium and titanium on the mechanical properties and microstructural development of cast steel. These elements play a critical role in enhancing mechanical strength, particularly after quenching and tempering, although there are evident trade-offs in ductility and impact toughness. In addition, the study discusses the damage mechanisms, focusing on the role of titanium nitrides in the cracking process.

Iron oxide synergistic vacuum carbothermal extraction of zinc from zinc sulfide

2024-12-05T20:33:35+01:00

To reduce the problems of large pollutant emissions and long process flow in the process of extracting zinc from zinc sulfide ore, the technical idea of iron oxide combined with vacuum carbothermal reduction to extract zinc from zinc sulfide ore is proposed. The source of iron oxide is metal smelting slag with high iron content. In vacuo, iron oxide is reduced to metallic iron by carbon. Iron replaces zinc sulfide to form zinc vapor, and zinc vapor is condensed to obtain metallic zinc. In this paper, zinc in zinc sulfide was extracted under vacuum conditions with iron powder, pure iron oxide powder, and iron oxide in roasting cyanide tailings as iron sources. The effects of reduction temperature and holding time on zinc volatilization rate were studied. The results show that when n_Fe : n_Zn = 1.1 : 1, 1000 °C, the initial pressure in the furnace is 10 Pa, iron powder, pure iron oxide powder, and iron oxide in roasting cyanide tailings can make the zinc volatilization rate in zinc sulfide reach more than 99 %. Different iron sources can react with the sulfur of zinc sulfide to form FeS, and no sulfur-containing gas is generated in the process of zinc extraction.

Prediction of Elastic Modulus, Yield Strength, and Tensile Strength in Biocompatible Titanium Alloys

2024-12-05T20:33:35+01:00

Titanium alloys are key materials in biomedical engineering, thanks to their exceptional mechanical properties and biocompatibility, which makes them indispensable for medical implants. With the increasing demand for such alloys, the integration of machine learning into their design offers a promising path to reduce costs and speed up the process. This study seeks to develop accurate machine learning models to predict the mechanical properties, including modulus of elasticity, tensile strength, and yield strength, of biocompatible titanium alloys. The results emphasized the significance of including heat treatment parameters and Poisson's ratio, which led to enhanced precision in the prediction of elastic modulus. Moreover, the key roles of iron and tin content in titanium alloys emerged as influential parameters for predicting tensile strength and yield strength, respectively.

Experimental Investigation on WAAM-based Functional Wear-Resistant Bimetallic Part

2024-12-05T20:33:35+01:00

Wire Arc Additive Manufacturing (WAAM) coupled with robotic systems enhances the fabrication of large-scale and complex metallic components utilized across various sectors such as aerospace, defense, maritime and automotive. Functional wear-resistant bimetallic parts are among the metallic components which can be produced via this manufacturing technology. Traditionally, manufacturing wear-resistant components involves cladding hard-facing materials onto a base metal, a process that is often complex, costly, and time-intensive. This paper proposes the adoption of the WAAM process for creating functional wear-resistant bimetallic part using hard-facing solid welding wire, aiming to improve wear resistance. The performance of wear-resistant bimetallic parts is significantly influenced by the selected multi-material, hardness distribution, interface morphology, and bond strength at the interface. In this study, the wear-resistant bimetallic part was built through the deposition of hard-facing welding wire onto the deposited 316L Si austenitic stainless steel. After the initial visual inspection and digital radiographic tests, hardness distribution was examined along with the macro and microstructural evaluations. In the subsequent analyses, tensile and Charpy V-notch tests were conducted using the extracted samples from the manufactured bimetallic part. As a result, the characterization and mechanical response of the robotic WAAM-based manufactured functional wear-resistant bimetallic part have been revealed.

Comparative investigation of ultrasonic cavitation erosion for different engineering materials

2024-12-05T20:33:35+01:00

Engineering materials are often exposed to various extremely harsh surroundings such as high temperatures and/or pressure, thermal shocks, aggressive solutions, or cavitation erosion. The phenomenon of cavitation erosion might be expected in conditions of fluid-flowing where the parts of equipment include turbine blades, high-speed propellers, or pump parts. Such conditions usually cause surface degradation with defects in the form of pits and fractures, resulting in strength deterioration with a potential risk of failure, as well as a reduction in the materials' lifespan that requires additional expenses for failure analysis, repair, and/or replacement of parts. This paper will present the main results regarding the study on cavitation erosion resistance of two different engineering materials, austenitic stainless steel 316L and CuAlNi shape memory alloy (SMA). Cavitation erosion testing was carried out using an ultrasonic vibratory method with a stationary sample. The comparison of the behavior between these two materials in cavitation erosion conditions will be shown based on the results of mass loss and analysis of the pits formed over time. Using image analysis tools, the surface damage levels were quantified. Detailed analyses revealed that SMA exhibited superior in terms of resistance and behavior compared to stainless steel.