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In the pursuit of achieving zero emissions, exploring the concept of recycling metal waste from industries and workshops (i.e., waste-free) is essential. This is because metal recycling not only helps conserve natural resources but also requires less energy as compared to the production of new products from virgin raw materials. The use of metal scrap in rapid tooling (RT) for injection molding is an interesting and viable approach. Recycling methods enable the recovery of valuable metal powders from various sources, such as electronic, industrial, and automobile scrap. Mechanical alloying is a potential opportunity for sustainable powder production as it has the capability to convert various starting materials with different initial sizes into powder particles through the ball milling process. Nevertheless, parameter factors, such as the type of ball milling, ball-to-powder ratio (BPR), rotation speed, grinding period, size and shape of the milling media, and process control agent (PCA), can influence the quality and characteristics of the metal powders produced. Despite potential drawbacks and environmental impacts, this process can still be a valuable method for recycling metals into powders. Further research is required to optimize the process. Furthermore, ball milling has been widely used in various industries, including recycling and metal mold production, to improve product properties in an environmentally friendly way. This review found that ball milling is the best tool for reducing the particle size of recycled metal chips and creating new metal powders to enhance mechanical properties and novelty for mold additive manufacturing (MAM) applications. Therefore, it is necessary to conduct further research on various parameters associated with ball milling to optimize the process of converting recycled copper chips into powder. This research will assist in attaining the highest level of efficiency and effectiveness in particle size reduction and powder quality. Lastly, this review also presents potential avenues for future research by exploring the application of RT in the ball milling technique.

Purpose Industries and businesses are pursuing Industry 4.0 technologies as well as adopting a circular approach focused on improving manufacturing processes through the reduction of wastes, CO2 emissions and mineral exploration to mitigate the impact of climate change. In this sense, additive manufacturing (AM), often referred to as 3D printing, can play a key role in the closed-loop of operations. However, academics and practitioners have scarcely discussed the feasibility of implementing AM alongside circular economy (CE) practices, the techniques and methods that this would require, or how AM could benefit sustainability and circularity. To address these gaps, this paper proposes a novel circular sustainable 3D printing model for scrap recycling in the automotive industry.Design/methodology/approach The methodology uses a literature review-based approach followed by empirical research using metal scraps as the raw material for fabricating a powder to input a metal 3D printer for generating sustainable automotive components. A conceptual sustainable circular model for the automotive industry is proposed. Next, is conducted a focus group comprises AM and automotive industry experts for evaluations.Findings The results indicate that the proposed model can be used to reintroduce waste back into the manufacturing chain as raw material for the on-demand manufacture and supply of automotive components and that it may also have social and environmental implications.Originality/value This paper’s contributions are threefold: it explores the combined use of Industry 4.0 (I4.0), CE and sustainability in the automotive industry, develops a new model to support the circularity and sustainability of the scrap chain and proposes the use of AM as a catalyst of CE practices by reproducing recycled components with a 3D printer for prototypes or fully functioning components.

In this study, the electrochemical deoxidation of Ti scrap metal was performed at 800, 850, 900, and 950 °C using graphite and Pt as the electrodes and molten MgCl 2 as the electrolyte. These temperatures were selected to investigate how the efficacy of deoxidation was affected by the Ti crystallographic structure, as the body-centered cubic β-Ti phase occurs above 882 °C. The results revealed that temperature significantly influences the oxygen diffusion rate and kinetics of deoxidation reactions. A corresponding kinetic model was developed to gain insights into the deoxidation mechanism. The measured oxygen content after deoxidation at 800, 850, 900, and 950 °C was 2100, 1900, 1500, and 3494 ppm, respectively. Furthermore, the effect of MgO activity on the Ti deoxidation rate was experimentally proven to be a function of temperature. These findings indicate that the best deoxidation performance is achieved at 900 °C, compared to the other tested temperatures.

Background From 2006 to 2011, the City of Houston received nearly 200 community complaints about air pollution coming from some metal recycling facilities. The investigation by the Houston Health Department (HHD) found that while operating within legal limits, emissions from facilities that use torch cutting, a technique generating metal aerosols, may increase health risks for neighboring residents. Choosing to use collaborative problem solving over legislative rulemaking, HHD reached out to The University of Texas Health Science Center at Houston (UTHealth) to further evaluate and develop plans to mitigate, if necessary, health risks associated with metal emissions from these facilities. Methods Utilizing a community-based participatory research approach, we constituted a research team from academia, HHD and an air quality advocacy group and a Community Advisory Board (CAB) to draw diverse stakeholders (i.e., frustrated and concerned residents and wary facility managers acting within their legal rights) into an equitable, trusting and respectful space to work together. Next, we investigated metal air pollution and inhalation health risks of adults living near metal recyclers and ascertained community views about environmental health using key informant interviews, focus groups and surveys. Finally, working collaboratively with the CAB, we developed neighborhood-specific public health action plans to address research findings. Results After overcoming challenges , the CAB evolved into an effective partnership with greater trust, goodwill, representation and power among members. Working together to translate and share health risk assessment results increased accessibility of the information. These results, coupled to community survey findings, set the groundwork for developing and implementing a stakeholder-informed action plan, which included a voluntary framework to reduce metal emissions in the scrap yard, improved lines of communication and environmental health leadership training. Tangible outcomes of enhanced capacity of our community and governmental partners included trained residents to conduct door-to-door surveys, adaptation of our field training protocol and survey by our community partner and development of a successful HHD program to engage residents to improve environmental health in their neighborhood. Conclusions Academic-government-community-industry partnerships can reduce environmental health disparities in underserved neighborhoods near industrial facilities.

The production of synthetic iron castings in Russia comprises 50% of all alloys produced; therefore, increasing their smelting efficiency is an urgent task in the industry. This process depends primarily on the efficiency of industrial frequency induction crucible furnaces using acid lining. In the present study, the properties of quartzite, which forms the basis of such a lining, were investigated. An analysis of the proposed variants for changing the composition of the acid lining for use at temperatures of 1550–1600 °C was conducted. Following the preliminary temperature treatment of raw quartzite, which was then subjected to a sintering regime, we determined the conditions under which it was possible to obtain a phase state, allowing for the operation of the lining at temperatures above 1450 °C. We determined the use of an electrocorundum of two fractions as an additive to the traditional composition of the acid lining. The industrial testing of a new liner composition for the smelting of synthetic cast iron in an induction crucible melting furnace with a single steel scrap-metal filling was assessed, which required the use of an increased amount of carburizing agent. The positive results obtained can be explained by the study of the spent lining, which withstood 345 smelting methods of genophasic rent analysis. The results of the test are based on the results obtained in a study conducted on the finished coating of the product.

Ferrochrome (FeCr) is the main source of virgin chromium (Cr) units used in modern-day chromium (Cr) containing alloys. The vast majority of produced Cr is used during the production of stainless steel, which owes its corrosion resistance mainly to the presence of Cr. In turn, stainless steel is mainly produced from Cr-containing scrap metal and FeCr, which is a relatively crude alloy between iron (Fe) and Cr. The production of FeCr is an energy and material-intensive process, and a relatively wide variety of by-products, typically classified as waste materials by the FeCr industry, are created during FeCr production. The type and extent of waste generation are dictated by the smelting route used and the management practices thereof employed by a specific smelter. In some cases, waste management of hazardous and non-hazardous materials may be classified as insufficient. Hazardous materials, such as hexavalent Cr, i.e., Cr(VI), -containing wastes, are only partially mitigated. Additionally, energy-containing wastes, such as carbon monoxide (CO)-rich off-gas, are typically discarded, and energy-invested materials, such as fine oxidative sintered chromite, are either stockpiled or sold as ordinary chromite. In cases where low-value containing wastes are generated, such as rejects from ore beneficiation processes, consistent and efficient processes are either difficult to employ or the return on investment of such processes is not economically viable. More so, the development of less carbon (C)-intensive (e.g., partial replacement of C reductants) and low-temperature pellet curing processes are currently not considered by the South African FeCr smelting industry. The reasoning for this is mainly due to increased operation costs (if improved waste management were to be implemented/higher cost reductants were used) and a lack of research initiatives. These reasons result in the stagnation of technologies. From an environmental point of view, smelting industries are pressured to reduce C emissions. An attractive approach for removing oxygen from the target metal oxides, and the mitigation of gaseous C, is by using hydrogen as a reductant. By doing so, water vapor is the only by-product. It is however expected that stable metal oxides, such as the Cr-oxide present in chromite, will be significantly more resistive to gaseous hydrogen-based reduction when compared to Fe-oxides. In this review, the various processes currently used by the South African FeCr industry are summarized in detail, and the waste materials per process step are identified. The limitations of current waste management regimes and possible alternative routes are discussed where applicable. Various management regimes are identified that could be improved, i.e., by utilizing the energy associated with CO-rich off-gas combustion, employing a low-temperature alternative chromite pelletization process, and considering the potential of hydrogen as a chromite reductant. These identified regimes are discussed in further detail, and alterative processes/approaches to waste management are proposed.

The aim of this research was to assess the distribution, sources, contamination status, ecological risk, and human health risk of heavy metals (HMs) in soil and sediments of a used-automobile spare part market in Nigeria. Forty-three (43) soil samples were collected within a spare part market section (SPMS-17 samples), market-residential section (MRES-10 samples), traffic section (TRAS-10 samples), and non-market residential section (NMRS- 6 samples). Fifteen (15) stream sediments were collected within and around SPMS. Based on average concentrations, HMs (As, Cd, Cr, Cu, Fe, Mo, Pb, and Zn) had their highest values in SPMS, and their minimum values were observed in NMRS. The high concentration was as a result of contributions from anthropogenic activities such as the direct discharge of used-lubricant oil, scrap metals, tire wear, and traffic emission in the environment. However, Al, Co, and Mn were derived from the geology of the area. The same trend was observed in the stream sediment section (STSS), except that in addition to Al, Co and Mn in soils, Cr was also sourced from geogenic activity. There were moderate to high enrichment/contamination factors of the anthropogenically sourced HMs, especially in the soil of SPMS, MRES, TRAS and stream sediments (STSS). Similarly, high potential ecological risk (Eri) and ecological risks (RI) were observed for As, Pb, and Cd in SPMS and STSS, while these were moderate in MRES and TRAS. Assessment of health risks was within acceptable limit for most of the HMs in the different sections for both adults and children, except As, Cd, and Pb in SPMS and STSS, which were beyond the acceptable limit for children. The carcinogenic risk was within the acceptable limit.

In this investigation, composite materials were manufactured of mixed scrap of Mg-based alloys and low melting point Sn–Pb eutectic by high energy ball milling, and their hydrogen generation performance was tested in NaCl solution. The effects of the ball milling duration and additive content on their microstructure and reactivity were investigated. Scanning electron microscopy (SEM) analysis indicated notable structural transformations of the particles during ball milling, and X-ray diffraction analysis (XRD) proved the formation of new intermetallic phases Mg2Sn and Mg2Pb, which were aimed to augment galvanic corrosion of the base metal. The dependency of the material’s reactivity on the activation time and additive content occurred to be non-monotonic. For all tested samples ball milling during the 1 h provided, the highest hydrogen generation rates and yields as compared to 0.5 and 2 h and compositions with 5 wt.% of the Sn–Pb alloy, demonstrated higher reactivity than those with 0, 2.5, and 10 wt.%.

The purpose of the foundry is to provide the consumer with blanks for general machine-building (special) purposes which are as close as possible to the size of the future part in full compliance with the requirements. The competitiveness of these products is primarily dependent on the use of efficient and reliable smelting equipment which meets the necessary cost. The replacement of high-value ironworks and ironworks iron with steel scrap using induction melting furnaces (ICFs) reduces the cost of producing synthetic cast iron. However, this results in temperatures greater than 1500 °C, reduced lining stability and increased downtime of the smelter. As a result of the research carried out, a technology for the use of quartzite is proposed. Thereby, the purpose of this work is to establish temperature regimes for the smelting of synthetic pig iron, allowing the use in metal filling up to 70–90% of steel scrap; this leads to a reduction in the cost of purchasing bulk materials (depending on the brand of cast iron) up to 50% and, thus, increases the efficiency of synthetic cast iron smelting and castings production in general. After removal of the original moisture and the subsequent sintering of the manufactured lining, it provides the possibility of melting using the melting temperatures 1550–1600 °C. It increases the efficiency of the operation of the melting furnaces and eliminates the consumption of the ironworks and the melting of the cast iron in the blast furnace, as well as the cost of the lost alloy. As a result, metallurgical production will be able to reduce the volume of production and supply of cast iron for ironworks, which will improve their environmental situation during the production and processing of necessary raw materials.