Recycling of Slags and Furnace Bricks in Non-Ferrous Metallurgy

Haver & Boecker Niagara: With a view to optimized process flow for the recycling of non-ferrous metals.

Non-ferrous metals are indispensable for the economy of highly technical industrialized countries. On the one hand, they provide a basis for existing technologies in electronics and electrical engineering, mechanical and automotive engineering, and the construction sector. And on the other hand, they also form the essence of future-focused technologies in many cases. Against this background, non-ferrous metals are an integral part of different options for minimizing climate-damaging greenhouse gases. Nevertheless, the primary and secondary metallurgical processes of non-ferrous metallurgy rank among the most energy- and raw material-intensive processes worldwide, but also offer great potential for improvement along the entire value chain.

Accordingly, Haver & Boecker Niagara is working intensively on optimizing the process flow in the treatment of non-ferrous metals by developing technically sound solutions that meet economic efficiency, sustainability and climate protection.

Resource-saving handling of non-ferrous metals
Based on the statement of the Federal Republic of Germany, represented by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, non-ferrous metals can be remelted and refined repeatedly without affecting the quality of the metals. Every form of recycling, however, is always associated with energy consumption. Therefore, for sustainable resource management, the focus has to be on reducing the total material input.

With that in mind, it is important to know the production of non-ferrous metals also generates different internal waste streams during production, such as slags, drosses, sludges and filter dust. These wastes are often recycled internally or externally as well. Overall, recycling offers major advantages in resource conservation compared with primary production. However, this process is not yet optimally mature at present.

In addition to the issue of material efficiency, energy supply is also a key factor. The energy consumption for melting the raw materials depends on the metal and the type of melting furnace used. Production from secondary raw materials (recycling) is generally associated with much lower energy consumption. That is particularly clear in the case of aluminum, where the saving compared with primary aluminum production is around 95 percent. Optimized processes and heat utilization have already significantly reduced energy consumption in recent years, the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety further note.

The solution for resource-saving melting furnaces
It is often necessary to adjust the granulometry of the non-ferrous metals-containing materials to operate the melting furnaces in a resource-saving manner and close to the process engineering optimum. The Head of Sales and Projects Department at Haver Engineering GmbH, Dr. Jan Lampke, takes a closer look at this process: “In plain language, granulometric adaptation of the materials containing non-ferrous metals means: dust and sludges must be pelletized, bucket excavated material, furnace bricks and slag must be crushed!”

On the other hand, the interplay between environmental protection and economic efficiency should not be ignored: “There is no doubt that the greatest lever for energy and resource savings is tailor-made process engineering that understands the technical requirements and meets the economic benefit”, adds the expert.

Dr. Lampke emphasizes the close cooperation with customers and the expertise of the service and sales staff as decisive factors for the development of efficient processing techniques in the field of non-ferrous metal-containing materials: “Our service and sales staff have kept up an intensive exchange with our customers worldwide for more than 130 years. Thus, our engineers not only have experience in the development of innovative machines for packaging and processing technology but also in the operation of the plants. This know-how has been used in plant engineering for decades. Storage, feeding, mixing, pelletizing, screening, packing, and conveying are our core competencies, which are profitably and forward-looking interlinked by intelligent automation technology. In this context, the processing of raw and residual materials is not rocket science, but only the intelligent linking of different machines and processes, whereby the material properties of the raw materials, as well as the products, always represent the decisive component of the selection process.”

Niagara customized processing plant for the recycling of furnace bricks and slag
The company’s years of experience, in-depth knowledge in the field of processing of non-ferrous materials, and the ability to develop sustainably and, at the same time, economically efficient solutions have led a well-known customer from the non-ferrous metallurgy sector to entrust the team with the realization of its vision, namely the development of a customized processing plant for the recycling of furnace bricks and slag.

The plant, which consists of a three-stage crushing process with an intelligent rejection of non-crushable foreign bodies and various classification stages, will soon be installed at the customer’s site. Up to 100,000 tons of non-ferrous slag and furnace bricks with a feed size of up to 0.5 m will be crushed to 0/2 mm so that the recycle can be pneumatically conveyed to or into the kiln. This is a classic brown-field project, whereby the stationary plant is implemented in the existing recycling process. The limited space available and the connection to the complex plant infrastructure represent an additional limiting component for the compact plant.

The project manager, Mr. Benjamin Gurra, emphasizes the importance of the in-depth research and development analyses in Haver & Boecker Niagara’s new technical center at Haver Engineering GmbH for the success of the project: “As part of a feasibility study, the furnace bricks and slags were first analyzed and the target parameters defined with the client so that the physical and chemical properties of the relevant non-ferrous metal-containing materials were then determined at the HAVER Institute and tests were carried out at the HAVER ENGINEERING GmbH technical center for crushing, classification and analysis of the pneumatic conveyability of the crushed material”, shares Mr. Gurra.

The Haver & Boecker Niagara team further clarifies that these findings allowed the entire plant layout to be modeled and calculated using Niagara NIAflow, a simulation software for all types of mineral process engineering applications. This simulation allowed the comparison and evaluation of different concepts. Thus, the preferred option could be worked out as part of the basic engineering to check how the required plant constellation could fit into the existing infrastructure.

All further steps were also in line with the already preserved Niagara Project Management System, with the client placing great emphasis on the early involvement of all stakeholders. In particular, he took into account the relevant authorities, especially to prove that all resulting restrictions from the German Federal Immission Control Act (BImSchG) regarding harmful environmental effects due to air pollution, noise, vibrations and similar processes were met and even exceeded.

Source: Haver Niagara GmbH

Haver & Boecker Niagara: The heaviest machine in Europe
The Niagara team has achieved another feat in this project: the construction of the heaviest screening machine in Europe. Dr. Metodi Zlatev, Head of Sales and Projects Department, provides additional information: “In a few months, also in the non-ferrous recycling sector, the heaviest screening machine in Europe with a weight of 61 t (including insulating frame to minimize dynamic forces) will be used for screening bucket spoil. However, this dimension is not so much a result of the process engineering aspects, but rather to the high safety requirements of the operation due to the enormous cyclic loads.”

“The high-performance screening machine for efficient dry and wet classification is actually used in typical mining applications but will also be able to demonstrate its advantages in metallurgy,” believes Zlatev. “Last but not least, our machines and plants are also used in iron and steel metallurgy. For example, in the recycling of blast furnace slags, granulated blast furnace slags, and in the very material-specific recycling of individual steel mill residues,” adds Zlatev.

Based on all these innovative solutions and Haver & Boecker Niagara’s diversified product portfolio, Niagara Team is confident that today’s reality, characterized by the enormous impact of environmental, economic and political changes, must be separated from the term “impossible”. Thanks to its unconditional dedication, years of know-how and innovation-promoting collaboration with customers, this project to optimize the process flow of non-ferrous metals processing has been achieved and the impossible has been attempted to reach the possible. As a result, Haver & Boecker Niagara offers the Perfect Flow for every process, plant and customer. Be part of this vision – move the future in its Perfect Flow together with Haver & Boecker Niagara!

(Published in GLOBAL RECYCLING Magazine 1/2022, Page 40, Advertorial, Photo: Haver Niagara GmbH)