International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This work is devoted to the study of a new technology for processing bar scrap – a precision shaft made of Cf53 structural steel (DIN 17212) that has proven its service life and produces high-quality finished metal products in the form of a screw reinforcement profile. The precision shaft used for recycling of its proven service life included two stages: preliminary deformation of the shaft on a radial shear rolling mill to obtain rods of the required diameter and create initial conditions for the formation of a gradient ultrafine-grained structure in the resulting screw profile; direct production of a screw profile with a gradient ultrafine-grained structure on a combined installation. The conducted research has shown that the new combined technological process of rolling bar scrap is feasible in practice and makes it possible to obtain a high-quality finished product from this scrap in the form of a screw reinforcement profile with a gradient ultrafine-grained structure.

In this study, the design and modeling of a shredding unit intended to fragment nonwoven waste fabrics and prepare them for recycling were carried out. Stress analyses were performed on the shaft attached to the blade, along with motor power and torque analyses required for smooth operation, and mass flow calculations. Mathematical models were developed based on these data. Additionally, structural analyses of the chassis, necessary for stable system operation, were conducted, resulting in a comprehensive mathematical model of the entire system.

This publication analyses the process of transforming the online economy into a circular one. The focus of the analysis is on the progress of the European Union member states in reducing waste. Member States’ progress towards a circular economy is slow. The circular business model should not be seen as wishful thinking, because it will be crucial for companies in the future. The circular economy is at the heart of the European Green Deal and plays a key role in decarbonisation and achieving climate neutrality by 2050 and in the fight against pollution. Circular economy means smarter use of resources. The circular economy is built using sustainable economic models based on innovation and technology to allow the repeated use of the same resources. Achieving a zero carbon footprint on the natural environment by 2050. is the top priority. This would only be possible if the world moves towards a circular economy, and this is one of the highlights of the Green Deal, while also aiming to increase the competitiveness of the economy.

In recent years, much attention has been paid to the recycling of Li-ion batteries (LIBs) [1, 2]. However, there are only few economic assessments on the recycling of LIBs even if, by 2030, it is possible to reach 2 million tons of spent LIBs/year worldwide [3, 4]. In this context, the present work aims to present a viable business model that is feasible and economically efficient and can be framed in a circular economic recycling technology of spent LIBs. The proposed business model uses literature data on the hydrometallurgical processing (HP) of spent LIBs. The business plan contains estimates of costs and revenues, and, also, estimates or projections concerning the state of the relevant markets and industries for the products resulting from spent LIBs.
Our work proposes a feasible and sustainable circular economy solution able to deliver critical materials such as cobalt, lithium, nickel, and copper for the supply chain of the LIBs manufacturing. From our estimate, valorising all recovered materials, the annual profit can reach around 600,000 $ for a commercial recycling plant that processes 125 tons/year of spent LIBs.

This work is devoted to the study of the use of radial-shear rolling mills for recycling bar scrap and some metal products from ferrous and non-ferrous metals that have served their service life to obtain a ready-made commercial product. In particular, the paper presents the results of computer modeling and experimental research of the process of scrap metal rolling in the form of rebar on a radialshear rolling mill into a round cross-section bar, which prove that some metal products that have served their service life after recycling using the proposed technology into finished commercial products in the form of bars can find further use without remelting.

Milliards of dollars are set aside for preserving the life on planet Earth and help climate change. Unfortunately, the advances in technology are incapable to help us sort out this vital problem, because the more advanced the technology nowadays is, more irresponsible we become in taking care about consequences after the expiration date of it. It is not only the plastic pollution of ocean of our planet that stops the formation of oxygen but also the irresponsible disposal of lithium-ion rechargeable batteries for smartphones, tablets, computers, electric smart devices and vehicles that are no longer in use, create ionizing radiation and form a radioactive background that affects living and non-living organisms inhabiting our planet. So, when the technology cannot help us, then perhaps the pure science would come to the rescue of preserving ourselves. There are laboratory researches about recycling lithium-ion batteries and here where we are – we are going to implement mathematics, algorithms, indexed arrays(vectors) for describing the benefit of manufacturing the recycling of lithium-ion batteries.

Regardless of the length of the period of use of the equipment, due to a change in technology, an increase in maintenance costs or the introduction of new requirements with a change in legislation, the machines become obsolete and are disposed of. The main methods for utilization of tractors and self-propelled agricultural machinery are considered. The equipment necessary for the disposal is also described. The methodology for determining the costs for utilization and the value of the equipment for utilization of the whole machine, element-by-element utilization and utilization after defecting has been supplemented.

The state of collection, storage and processing of some main waste in Bulgaria is under consideration. In accordance with the legislation in force in Bulgaria and the EU, separate collection of waste is increasingly necessary. Some examples of different types of waste show what the actual condition is and show good examples of work in this area.

By recycling old products mainly the elements, which are contained in large amounts in the product, are regained. Taking metal coated Waste Electrical and Electronic Equipment (WEEE) as an example, this is the plate of the component cover, which is made of steel or aluminum, the included plastic, the printed circuit board’s material and copper. Those materials, which are contained on the printed circuit board belonging to the area of specialty metals such as tantalum, indium, palladium etc., cannot economically be extracted from a shredder plant’s output mass flow. To solve this problem, a new approach for an automatic decomposition of metal coated components is introduced based on the process principle of the roll crusher. For finding a solution the systematic design approach and a first pilot plant’s results are presented. Based on these results, conclusions for future developments are derived.

The car is prevalently considered as a technical system that produces costs and pollution, also as a source of exhausted parts and recycled raw material. In the course of entire life cycle it seriously deteriorates natural balance to the extent to appear as a threat to overall ecological biodiversity on the Earth. Due to mass production and use what includes building-in vast number of materials and component that yield adverse effects on human health, engine cars has become one of major problems of today.
The management of secondary waste requires an established flow of integrated information as well as an complementary system of knowledge and methods regarding landfill remnants reduction and adequate treatment of useful materials. Global automotive industry incites development of national economies and integrates contemporary achievements in the areas of techniques, technology and other scientific disciplines. Thus, the aspects of energy efficiency, waste recycling and environment protection sustainable development environmental shall be taken into account in car designing and production.

The paper summarizes studies pertaining to an innovative method of polymeric chips and sawdust boards production. RD boards are manufactured from post-production waste in the form of chips. The chips are heated and pressed under small pressure in metal forms. The product is characterized with good sound and thermal insulation, small mass, and low manufacturing cost. As a consequence, it can be applied in several types of products as a filler.