Apparatus-technological scheme of tin cans scrap recycling with obtaining technical products

The article is devoted to the study of reducing the technogenic load on the environment due to the integrated processing of household metal scrap. A waste-free, resource-saving, and environmentally safe method is proposed for extracting technical products from tin cans scrap - iron (III) oxide, tin (II) complex, suitable for further use, as well as fertilizer for agricultural crops. As a result of theoretical and experimental studies, the direction of cans scrap recycling was selected with an assessment of the parameters and factors affecting the reagent process of scrap disposal. To verify the proposed method for can scrap processing in experimental studies, the reagent method and physical modeling were used together. The processes of the reagent can scrap recycling were studied in a laboratory-scale plant. The results of studies on the reagent can scrap processing with the individual component allocation in the form of their derivatives are presented. A block diagram and a hardware-technological scheme for scrap processing with the receipt of technical products have been developed. The possibility of processing other metal-containing wastes according to the proposed scheme, for example, electrical production, is shown.

Microstructure and Properties of As-Cast and Heat-Treated 2017A Aluminium Alloy Obtained from Scrap Recycling

The continuous increase in the consumption of aluminium and its alloys has led to an increase in the amount of aluminium scrap. Due to environmental protection, and to reduce the costs of manufacturing aluminum in recent years, a lot of research is devoted to recycling of aluminum alloys. The paper presents the results of research concerning the possibility of manufacturing standardized alloy 2017A from commercial and post-production scrap by continuous casting. Obtained from recycling process ingots were subjected to analysis of chemical composition and intermetallic phase composition. Based on the results of light microscopy (LM), scanning electron microscopy + electron dispersive spectroscopy (SEM + EDS), and X-ray diffraction (XRD) the following phases in the as-cast state were identified: θ-Al2Cu, β-Mg2Si, Al7Cu2Fe, Q-Al4Cu2Mg8Si7, and α-Al15(FeMn)3(SiCu)2. During solution heat treatment most of the primary precipitates of intermetallic phases, like θ-Al2Cu, β-Mg2Si, and Q-Al4Cu2Mg8Si7, were dissolved in the solid solution α-Al, and during natural and artificial aging they precipitate as strengthening phases θ-Al2Cu and Q-Al4Cu2Mg8Si7 with high dispersion. The highest hardness—150.3 HB—of 2017A alloy was obtained after solution heat treatment from 510 °C and aging at 175 °C. In the static tensile test the mechanical (Rm and Rp0.2) and plastic (A5) properties were determined for 2017A alloy in the cast state and after T4 heat treatment. The highest strength properties—tensile strength Rm = 450.5 MPa and yield strength R0.2 = 268.7 MPa with good relative elongation A5 = 14.65%, were obtained after solution heat treatment at 510 °C/6 h/water quenching and natural aging at 25 °C for 70 h. The alloy manufactured from recycled scrap is characterized by relatively high mechanical properties.

Environmental impact of high-value gold scrap recycling

Purpose The gold routes satisfying the global gold supply are mining (74%), recycling of high-value gold (23%), and electronic scraps (3%). Besides its applications in the investment, jewelry, and industrial sector, gold also has a bad image. The gold production in industrial as well as artisanal and small-scale mines creates negative impacts such as resource depletion, extensive chemical use, toxic emissions, high energy consumption, and social concerns that are of great importance. On the other hand, almost all gold is recycled and has historically always been. In common life cycle assessment (LCA) databases, there is no data on recycling of high-value gold available. This article attempts to answer the question what the ecological benefits of this recycling are. Method In this study, we were able to collect process data on the most commonly used high-value gold scrap recycling process, the aqua regia method, from several state-of-the-art German refineries. With this data, life cycle inventories were created and a life cycle model was produced to finally generate life cycle impacts of high-value gold scrap recycling. Results This study contains the corresponding inventories and thus enables other interested parties to use these processes for their own LCA studies. The results show that high-value gold scrap recycling has a considerably lower environmental impact than electronic gold scrap recycling and mining. For example, high-value gold scrap recycling in Germany results in a cumulative energy demand (CED) of 820 MJ and a global warming potential (GWP) of 53 kg-CO2-Eq. per kg gold. In comparison, common datasets indicate CED and GWP levels of nearly 8 GJ and 1 t-CO2-Eq. per kg gold, respectively, for electronic scrap recycling and levels of 240 GJ and 16 t-CO2-Eq. per kg gold, respectively, for mining. Conclusion The results show that buying gold from precious metal recycling facilities with high technological standards and a reliable origin of the recycling material is about 300 times better than primary production.

Integrated Battery Scrap Recycling and Nickel Slag Cleaning with Methane Reduction

Innovative recycling routes are needed to fulfill the increasing demand for battery raw materials to ensure sufficiency in the future. The integration of battery scrap recycling and nickel slag cleaning by reduction with methane was experimentally researched for the first time in this study. Industrial nickel slag from the direct Outotec nickel flash smelting (DON) process was mixed with both synthetic and industrial battery scrap. The end products of the slag-scrap mixtures after reduction at 1400 °C in a CH4 (5 vol %)-N2 atmosphere were an Ni–Co–Cu–Fe metal alloy and FeOx–SiO2 slag. It was noted that a higher initial amount of cobalt in the feed mixture increased the recovery of cobalt to the metal alloy. Increasing the reduction time decreased the fraction of sulfur in the metal alloy and magnetite in the slag. After reduction, manganese was deported in the slag and most of the zinc volatilized. This study confirmed the possibility of replacing coke with methane as a non-fossil reductant in nickel slag cleaning on a laboratory scale, and the recovery of battery metals cobalt and nickel in the slag cleaning process with good yields.

A Study of Porosity of Products Sintered from BrS30 Alloy Electro-Erosion Powders

The article discusses a topical issue of scrap metal recycling, in particular BrS30 alloy scrap recycling, into powders for their repeated use to fabricate and harden machine parts. Nowadays, one of the most promising method of processing any conductive material is electro-erosion dispersion, which is non-waste, eco-friendly and energy-efficient. The paper presents the findings of a research of porosity of products, sintered from leaded bronze pressed powders, obtained by electro-erosion dispersion in distilled water. It was determined that in uniaxial pressing of the powder using a desktop hydraulic press, and in isostatic pressing of the powder using an isostatic press, and further sintering of the obtained samples in a folding tube furnace, the porosity was 0.61% and 1.44%, respectively.

The beginning and the end of the aluminium value chain

Metallic aluminium does not naturally occur in nature, and it was largely unknown, virtually a mystery, until 200 years ago. The modern aluminium production using a hydrometallurgical refining process for making alumina followed by electrolysis of this mineral was first developed in 1886 and, in principle, the same technology is still used to this day. About 90% of alumina refineries in the world use the Bayer process for refining Bauxite ore. It is very efficient, but it can only be used on high quality bauxite with low content of admixtures, especially silicon. The Bayer process also generates a Bauxite Residue (BR), maybe better known as Red Mud (RM) which is a thick red-brown, high-basicity paste consisting of silicon, iron, aluminium, titanium and others. The International Institute of Aluminium estimates that since 1886 almost a billion tonnes of aluminium were produced around the world with three fourths of this amount still being in use today, of which about 35% is located in buildings and structures, 30% in electric cables and equipment and 30% in transport. Aluminium scrap is collected all over the world. In the home, it mostly consists of aluminium beverage cans. It is claimed that 1 ton of recycled empty beverage cans save 8 tons of bauxite, 4 kg of various fluorides and 14 kWh of electricity. Additionally, recycling aluminium significantly reduces the negative environmental impact of ever-expanding RM landfills. As the idea of environmental responsibility is gaining more and more traction, separate household scrap recycling is becoming more and more popular around the world. How challenges related to such activity can be met will be the main topic of this paper alongside discussing new developments for alumina production without RM generation.