Mill scale

Mill scale is formed on the outer surface of plates, rolls, sheets or profiles when iron and steel are heated for rolling, forging, or other processing.

Being produced during the reheating, conditioning and hot rolling operation, mill scale initially adheres to the steel surface and protects it from atmospheric corrosion, provided no break occurs in this coating. It can be removed from the steel surface by flame cleaning, pickling or abrasive blasting according to the steel mill technology.

From the chemical and physical analysis performed on the scrap, and according to the European Environmental rules, the material has been classified as a special non dangerous waste, listed in green list.

In particular the Mill Scale can be classified as follows:

Physical properties

At a visual inspection it appears as hard brittle sand that is mainly composed of iron oxides, mostly ferric, and it is bluish black in colour. Its physical state is solid and powdered. The material is stable and it is insoluble in water.

Density (g/cm3) 5.7
Melting Point (°C) 1369°
Specific Gravity (g/cc) 6.02

Tab.1 This data is believed to be accurate and was obtained from recognized technical sources, but cannot be warranted as to its accuracy or sufficiency.

Chemical properties

Mill Scale has been classified has an UVCB Substance since it is made of a large number of constituents and its composition can change according to the metallurgical plant production (reinforcement bar, special steel etc.)
The average chemical composition is detailed in Tab.2:

Parameter Value(%)
Fe 71.1
Cr 0.071
Si 0.61
SiO2 1.32
Al 0.15
Al2O3 0.29
Ca 0.44
CaO 0.62
Mg 0.12
MgO 0.205
Ti 0.007
TiO2 0.012
P 0.059
P2O5 0.137
Na 0.28
Na2O 0.38
K 0.02
K2O 0.025
Mn 0.568

Tab.2. Average Chemical Composition. Please note that these data are believed to be accurate and representative of an average composition, but these details cannot be warranted as sufficient since the chemical composition can vary sensibly according to the production plant.

The iron detected in the material is present in different chemical forms, and is composed by high-purity iron oxidized such as:

The hard blue-black scales also contain valuable alloy materials such as wolfram, vanadium and molybdenum.
It is stable and insoluble in water and alkalis and soluble in most strong acids.
As highlighted by the chemical analysis above, our mill scale does not contain any dangerous, inflammable, radioactive or explosive substances. The material is free of dirt, nonferrous metals, or foreign material of any kind, and excessive rust and corrosion.

Conversion of mill scale waste into valuable products

The material can be recovered in different processes and recycling plant, such as:

Packing and loading

The information above can be by no means an exhaustive listing of our mill scale characteristics. Please note that according the end user requirements we can select and process a bespoke source that meets your criteria. The material can be processed and delivered in container or in bulk vessel, but in strict compliance with the European laws regulating the trans-boundary shipment of waste materials.

For further technical details, please feel free to contact us.

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REA No: UD - 266995

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