Products steagran® Production steagran boiler slag is produced from the melt of non-combustible, mineral components of the coal, which is solidified in a water quench. Boiler slag is created as an industrial by-product in coal-fired power plants during the production of steam, heat, and electricity. Mineral coal consists of 80 to 95% carbon and 5 to 20% mineral components (ashes). Accompanying rock, which is non-combustible as well, can also be contained in the coal. For the production of electricity from coal, the coal and its mineral components are pulverized and blown into the boiler of the power plant. In a slag tap boiler (wet bottom boiler), the non-combustible mineral components are melted by the temperatures in the furnace chamber, which are above the ash melting point of 1400 to 1500°C (2650 to 2750°F). The resulting liquid slag collects at the base of the boiler and flows through an orifice into a water quench installed below. The instant cooling causes the melted, non-combustible components to solidify to granulated material, the steagran. In power plants using slag tap boilers, 70 to 100% of all ashes produced are boiler slag. The remaining part is fly ash, which is either returned into the boiler and melted there, or discharged from the process. The utilization rate of steagran boiler slag has been 100% for several years already. The goal of a closed loop recycling management has thus successfully been achieved in this case. The amount of boiler slag produced will decrease in the coming years, though, because slag tap boilers are mainly used in older power plants. Properties Due to the instant cooling of the liquid stream of melted ash in the water quench, the material bursts into granules of up to 10 mm in size, the steagran boiler slag. During the further cooling, the residual stress in the material caused by the temperature stress can lead to fissures and fractures of the particles. This residual stress can be reduced by various processing steps. steagran G is sieved boiler slag with a particle size of up to 8 mm. It has a slightly higher pressure resistance than the raw steagran material. A further increase of pressure resistance can be achieved by crushing the material. The crushing reduces the residual stress so that the resulting material, called steagran P, has a pressure resistance comparable to that of basalt rock. steagran Edelbrechsand is produced from crushed and dried raw boiler slag. After being classed into particle sizes of 1 to 3 mm, it is passed through a magnetic separator. Therefore steagran Edelbrechsand is almost free of oxidizable components. Particle size distribution of steagran Particle density 2.4 - 2.6 kg/dm³ Bulk density 1.05 - 1.4 kg/dm³ Proctor density 1.3 - 1.5 kg/dm³ (independent of water content) Cavity volume 37 - 42 % Shearing resistance 40° - 45° Permeabilityindex kf [1] * 10-3m/s Value range of some exemplary material properties Due to the conditions during its creation, steagran is a glassy, angular, and almost non-porous material. The dark gray or black color is caused by the relatively high content of iron and manganese. Like natural aluminate silicates, steagran mainly consists of compounds of silicon, aluminum, and iron. SiO2 47 - 53 AL2O3 26 - 30 Fe2O3 3.0 - 10 CaO 2.0 - 6.5 MgO 1.1 - 3.0 SO3 < 0.2 K2O 4.0 - 5.0 Na2O 0.9 - 1.5 Cl < 0.04 Value range of some exemplary material analysis results steagran is highly environment-friendly. It does not contain any soluble salts, and the contained trace elements are firmly integrated in the glass matrix and thus cannot leach out. All relevant limits of the German drinking water ordinance are kept. Applications Regarding its composition, shape, and structure, steagran is very similar to mineral construction materials such as sand, gravel, or crushed stones. Due to its chemical and physical properties and its high quality, steagran can be used in many areas of the building industry and the construction material industry. Road and path construction SurfaceBase layersSubgrade Raw steagran® Concrete andconcrete products Ready-mix concreteConcrete productsPre-fabricated concrete partsFloor pavement steagran® G,steagran® PEdelbrechsand steagran® Stonework Sand-lime bricksConcrete bricksChimney bricks steagran® G,steagran® P Landfill construction Filter layersRoot space drainageGas drainage steagran® Rohgranulat Mining Backfilling material steagran® Rohgranulat Others Blasting gritWinter gritPlant-growing granules steagran® is a registered trademark of STEAG Entsorgungs-GmbH
steagran boiler slag is produced from the melt of non-combustible, mineral components of the coal, which is solidified in a water quench.
Boiler slag is created as an industrial by-product in coal-fired power plants during the production of steam, heat, and electricity. Mineral coal consists of 80 to 95% carbon and 5 to 20% mineral components (ashes). Accompanying rock, which is non-combustible as well, can also be contained in the coal. For the production of electricity from coal, the coal and its mineral components are pulverized and blown into the boiler of the power plant.
In a slag tap boiler (wet bottom boiler), the non-combustible mineral components are melted by the temperatures in the furnace chamber, which are above the ash melting point of 1400 to 1500°C (2650 to 2750°F). The resulting liquid slag collects at the base of the boiler and flows through an orifice into a water quench installed below. The instant cooling causes the melted, non-combustible components to solidify to granulated material, the steagran.
In power plants using slag tap boilers, 70 to 100% of all ashes produced are boiler slag. The remaining part is fly ash, which is either returned into the boiler and melted there, or discharged from the process.
The utilization rate of steagran boiler slag has been 100% for several years already. The goal of a closed loop recycling management has thus successfully been achieved in this case.
The amount of boiler slag produced will decrease in the coming years, though, because slag tap boilers are mainly used in older power plants.
Properties
Due to the instant cooling of the liquid stream of melted ash in the water quench, the material bursts into granules of up to 10 mm in size, the steagran boiler slag. During the further cooling, the residual stress in the material caused by the temperature stress can lead to fissures and fractures of the particles. This residual stress can be reduced by various processing steps.
steagran G is sieved boiler slag with a particle size of up to 8 mm. It has a slightly higher pressure resistance than the raw steagran material. A further increase of pressure resistance can be achieved by crushing the material. The crushing reduces the residual stress so that the resulting material, called steagran P, has a pressure resistance comparable to that of basalt rock.
steagran Edelbrechsand is produced from crushed and dried raw boiler slag. After being classed into particle sizes of 1 to 3 mm, it is passed through a magnetic separator. Therefore steagran Edelbrechsand is almost free of oxidizable components.
Value range of some exemplary material properties
steagran is highly environment-friendly. It does not contain any soluble salts, and the contained trace elements are firmly integrated in the glass matrix and thus cannot leach out. All relevant limits of the German drinking water ordinance are kept.
Applications
Regarding its composition, shape, and structure, steagran is very similar to mineral construction materials such as sand, gravel, or crushed stones. Due to its chemical and physical properties and its high quality, steagran can be used in many areas of the building industry and the construction material industry.
steagran® is a registered trademark of STEAG Entsorgungs-GmbH