The operation of an integrated steel mill such as CSP generates a series of by-products with high value both for internal consumption at the mill and sale to other companies as raw material.
In accordance with its strategic vision, CSP uses state-of-the-art processes and equipment so that these by-products can be managed and used properly, with the least environmental impact possible. As a result, the company is able to reuse, for example, 97% of the solid waste generated, an index higher than the average of 95% in the steel sector in Brazil.
CSP has systems to use 100% of the gases generated in the production processes. The main gases are coke oven gas (COG), blast furnace gas (BFG), and Linz-Donawitz gas (LDG). These consumables are treated (removal of impurities and unwanted substances), stored, and distributed by a pipeline network equipped with pressure control systems.
Part of these by-products is intended for the generation of electricity. CSP, who has a 200 MW/h consumption, is self-sufficient in electricity thanks to its own thermoelectric power plant. The power plant has a capacity of 218 MW/h, which is enough to meet the company’s demand and supply a city with 150,000 people. The electricity surplus is commercialized in the free energy market.
As these gases have high heat potential, they’re also used as fuel in the production areas.
With this, the company contributes to reduce the emission of gases responsible for the greenhouse effect, known as global warming.
Steelmaking Plant and Blast Furnace Slag
The use of new technologies and state-of-the-art equipment is one of CSP’s greatest advantages, which includes the application of Baosteel Slag Short Flow (BSSF), a brand new process to Brazil. In this process, the liquid slag coming from the steelmaking plant is poured into a rotating drum, where it’s cooled down through water jets, with consequent granulation, followed by magnetic separation. The process is clean, fast, safe and generates a slag of higher quality than the one obtained through the traditional way. This adds value to the material, enabling its use as a by-product in the cement industry, much like blast furnace slags.
An important fact is that, for each ton of pig iron produced, an average of 300 kg of blast furnace slag are generated. Furthermore, for each ton of liquid steel processed, approximately 100 to 150 kg of steel plant slag are generated.
Learn more about the main steelmaking process by-products:
These are steel by-products, mainly from the Blast Furnace, with a high content of silicon. Commercialized by CSP as a raw material, they are used for cement production or as a paving base or under base on streets, roads, runways and yards. This by-product reduces the cost of these works by 30%, in addition to requiring less maintenance due to its great resistance and durability.
The Blast Furnace sludge is a residue consisting predominantly of iron oxide and coke breeze. CSP sells this product to the ceramic industry with excellent results. Steel sludge can represent up to 5% in the composition of the products. It brings great advantages for this sector, because it increases the water absorption, ensuring more resistant products. Additionally, it contributes to reduce energy consumption in the ceramic burning process.
The Blast Furnace sludge is a residue consisting predominantly of iron oxide and coke breeze. CSP sells this product to the ceramic industry with excellent results. Manufactured bricks have around 5% steel slag in their composition. It brings great advantages for this sector, because it increases water absorption, ensuring more resistant products. Additionally, it contributes to reduce energy consumption in the ceramic firing process.
CSP makes sure the gases released during its several steel production processes are cleaned, eliminating all particulate matter, which in many cases is also a by-product. Coke breeze is a very fine solid resulting from some of these dedusting processes that will become a by-product to be commercialized as source of energy to different industries, such as the cement and ceramic industries. Its chemical composition contains predominantly carbon and ash.
Crude coal tar
Crude coal tar is one of the by-products that results from processing mineral coal to produce coke, one of CSP’s main raw materials. It consists essentially of aromatic hydrocarbons, such as benzene, phenols, naphthalene, cresol, anthracene and tar. Approximately 30 to 50 kg of tar can be obtained from one ton of coal.
CSP commercializes this consumable to companies that process and sell the derivative to many different segments, such as disinfectants, waterproofing agents, pharmaceuticals, plastics, metallurgical products, among others. The main tar by-product and flagship of the carbon-chemical industry development is pitch, which is used in the manufacture of electrodes for aluminum.
BTX Light Oil:
During the process of transforming coal into coke, the gases are scrubbed and BTX is collected after separating the tar. Therefore, BTX is also a result of the coke oven gas treatment. BTX is a yellowish liquid almost totally composed of benzene, toluene and xylene. It has a distinctive smell, resembling some contact glues (“shoemaker’s glue”). CSP commercializes it to companies that produce derivatives that are used in the solvent, paint and plastics industries.
The last stage of the coke oven gas treatment is able to collect high purity liquid sulfur, a yellow solid at room temperatures, but that is kept at above 127°C temperatures in trucks to become liquid. CSP commercializes the product to be used in the manufacture of linear alkylbenzene sulfonic acid, which is widely used in the chemical industry as the most popular surfactant to make liquid and powder detergents due to its proven environmental compatibility and excellent cost/benefit ratio.
The steel mill consumes many different supplies and materials. Many types of materials are generated during support activities, especially maintenance work. CSP commercializes several of those, seeking a use not only for materials (used oils, containers, packaging, etc.) but for equipment that was once useful in its activities and that can still be useful in other processes. The sales are made by a specialized team that direct these items to various markets.