Pig iron skulls from desulphurization

(EWC 19.12.02, B10 10)

Pig iron skulls, commonly named as Skim Iron, is a rich by-product derived from the desulphurisation process of pig iron, after its production in a blast furnace. The skimming process removes the excess waste components, such as the sulphur, silica, and phosphorous contained in the foam floating on top of the desulphurization ladle. However, a ferrous slag, highly rich in iron (Fe) content, is also harvested and can be recycled to produce fresh steel.

Physical Description
The Skim Iron is a ferrous by-product, which has a reasonably stable chemistry and is particularly rich in Fe (from 70% to 90% Fe content). As such, the iron has different levels of contaminants (S, P, Mg, Si).

To enhance its usability, the material is processed and screened through various steps of dry screening, crushing, and magnetic separation, aimed at selecting the different fractions.
Once this process is completed, we obtain three main qualities:

• 1. >85% Fe on average – over 350 mm Fraction, (Max Size 800mm)
• 2. >75% Fe on average – 80-350 mm Fraction
• 3. >70% Fe on average – 20-80 mm Fraction

Its Fe content can be estimated by the water displacement test.

Chemical Description
The Pig Iron slag/Skim Iron has a high carbon content, which can be as much as 4.5% carbon (C), as highlighted by the chemical analysis below:

Tab.1. Average chemical composition. Please note that these data are believed to be accurate and representative of the average composition.

The skim iron may offer competitive advantages in comparison with other ferrous scrap, such as:

• High Fe and carbon content, compared to similar raw materials;
• Controlled levels of sulphur and phosphorus, compared to similar raw materials;
• Homogeneous chemical and physical composition;
• A lower price than HMS1 & 2: this allows our customers to reduce their production costs while increasing their competitiveness.

Method of Manufacture
The desulphurisation process is carried out in a ladle or a torpedo-car. After the desulphurisation process, the torpedo-car is moved to a dedicated area for tapping. After tapping from the torpedo-car, the slag skimming occurs. The most common method for removing the sulphur-rich slag is to tilt the transport ladle and rake the slag with a skimmer. The slag is transported, for cooling, to a separate area where it is ready for processing. After the skimming process, the hot metal is ready for charging into a BOF to produce crude steel.

Conversion of Skim Iron/Pig Iron Slag Into Valuable Products
The material can be recovered in different processes and recycling plants, for example in the production of Pig Iron (R4).

Packing and Loading
Once cooled, the skim iron can be processed and delivered in 20’ containers or in bulk vessels. We act in strict compliance with the Basel Convention and with the European laws, that regulate the trans-boundary shipments of waste materials. The information above can be, by no means, an exhaustive listing of our iron and steel skulls characteristics. Please note that according to the end-user requirements, we can select and process a bespoke raw material, aimed at matching our customers’ criteria.