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A component of the sustainable circular economy

Steel production generates by-products that have been contributing to a sustainable circular economy and to resource conservation in important ways for over a century. Ferrous slags from blast furnaces as well as slags from steel plants and coal recyclables from coking plants are valuable, quality-controlled by-products. They offer a wide range of applications in a variety of sectors, including as raw materials for the cement, chemical and pharmaceutical industries or as starting materials and finished products for the construction materials industry and the processing industry, including agriculture.

Iron slag is used not only for the construction of buildings, roads and bridges, but also as a fertilizer for plants. Crude benzene is used to produce plastics and medical products. Electrode binding agents, which            are required for aluminum production, are made from raw materials such as tar.

By using these by-products, we are significantly helping conserve natural resources and actively helping protect the environment.

Stahl-Holding-Saar and its affiliated subsidiaries primarily offer iron and steel slags (blast furnace slag and steelworks slag) and by-products from coking plants.

Production and use of by-products

Granulated blast furnace slag

Blast furnace slag is smelted during the production of hot metal. It is then quickly cooled with water in a downstream granulation plant to form glassy, solidified granulate with latent hydraulic properties. Due to its hydraulic properties, granulated blast furnace slag is primarily used in the cement industry as an alternative raw material for production of various cements. Granulated blast furnace slag is also used in the glass industry for producing flat glass (e.g. window panes) and hollow glass (e.g. bottles).

Blast furnace lump slag (HOS)

During the hot metal production process in the blast furnace, blast furnace slag is also produced, which slowly solidifies in crystalline form in slag beds. After processing by crushing and screening, this slag can be used for various applications.

In road construction, blast furnace slag (HOS) is used in various grain sizes, both in unbound frost protection and in gravel base courses as well as in asphalt base courses.

Blast furnace lump slag is not exclusively produced as a pure construction material mixture for road construction. Construction material mixtures have been developed for special customer requirements, particularly in French road construction, by adding granulated blast furnace slag (under the brand name LAROGRAVE) or converter slag (under the brand name COMBIDILL).

HOS is used as a raw material in the cement industry to manufacture clinker.

Blast furnace lump slag is also used in the production of rock wool, which features numerous possible applications such as exterior wall, roof, floor and ceiling insulation, especially as sound and heat insulation.

LD slag (converter slag)

LD slag is produced in the converter during crude steel production using the Linz-Donauwitz process. Construction materials produced from it and marketed with the trade name SCODILL are used in various grain sizes for open road construction (e.g. forest roads, agricultural roads) and road verges.

Ladle slag

Ladle slag is produced as molten rock during secondary metallurgy and during continuous casting as part of steel production. Because of its composition, our ladle slag is also used in the production of cement clinker. Through targeted processing of LD slag and ladle slag, siliceous lime fertilizers are produced from the lime-containing by-products in accordance with the German Fertilizer Ordinance and the European Fertilizer Product Ordinance.

Other possible applications for ferrous slags

  • Use as an abrasive
  • Use as a precipitating and neutralizing agent
  • Use as a component of metallurgical processes, for example as a slag former
  • Use as a pH regulator in chemical processes

By-products from the coking plant for the chemical, pharmaceutical and other industries

Coal derivatives

Hard coal is heated during the coking process to over 1,200 °C under airtight conditions. During this process, volatile components escape and form coke oven crude gas. The coal recyclables tar, benzene and sulfur are extracted in various cooling and purification steps.

Coal tar

Formation: During cooling of the raw coke oven gas produced during the coking process.
Use: Extraction of aromatics and carbon black oils for the chemical industry and tire production, electrode pitch for the aluminum industry.

Crude benzene

Formation: Separated from the coke oven gas during a scrubbing process.
Use: Benzene is an important starting material for various products in the chemical industry, such as for the production of styrene.


Formation: Obtained in a Claus plant during desulfurization of the coke oven gas.
Use: Used in the chemical and pharmaceutical industries for production of such things as sulfuric acid, dyes and fertilizers.


We work together with our customers to develop products that are perfectly tailored to their requirements.

We will be happy to provide you with further information on request.
We look forward to hearing from you.


Product descriptions



Daniel Leidinger
General Manager Sales by-products

Phone: +49 6831 472425


Antoine Zimmer

Phone: +49 6831 475360