Sustainable Steel Making through Improved Phosphorous Control
in the Basic Oxygen Furnace
This PhD is a 3 year CASE award studentship between WMG and our industrial partner
Tata Steel.
Supervisor:
The project will be co-supervised by Prof Seetharaman, Royal Academy of Engineering /
Tata Steel Research Chair in Low Carbon Materials Technologies, and an Industrial
Scientist from TATA R&D.
Background:
Sustainable iron manufacturing requires flexibility with regards to raw materials. In the
past five years the price of iron ore has risen by 400% and it is therefore of vital
importance to enable flexibility with regards to the source of iron-ore.
An impediment to achieving this is the phosphorous present in ores. Low phosphorus
content in the final steel product is essential for steel applications where high ductility is
required, such as thin sheets, deep drawn, pipelines and automobile exteriors.
Unfortunately there is a great variation between ores. The iron ores available in the
USA have phosphorus contents from 0.030% to 0.060%P. In South America, Brazilian
ores have 0.035% to 0.055%P while Venezuela and Peru both have contents around
0.090%P. Russia, Kazakhstan and China have phosphorus content varying from 0.040%
to 0.150%P.
To enable manufacturing in such a way that ore flexibility can be implemented it is
important to be able to control the amount of phosphorous. In the United States and
Europe, phosphorus control is achieved in the Basic Oxygen Furnace where
phosphorous dissolved in the molten metal phase is transferred to the molten oxide
slag phase. Over 90% of the initial phosphorus in the melt can be removed in the BOF.
The refining capacity of the slag depends on many variables such as slag and metal
compositions, temperature, time and intensity of slag/metal stirring. Most fundamental
studies on the phosphorous transfer reaction have been limited to thermodynamic
studies assuming a flat interface between the slag and steel which does not accurately
reflect the conditions in the reactor. Slag/metal reactions are limited to 2-phase
interfaces and it is therefore important to understand the role of a non-sharp interface
including drops. It is moreover important to understand the transient path of the
reaction represented by the chemistry changes in the slag and metal phases.
Project:
This project intends to study the effects of drop-formation and evaluate the extent of
refining that is carried out from metal drops as compared to the bulk slag. The IMPHOS
project carried out by TATA-steel Europe was the first experimental study which
captured samples in the bulk and emulsified phases as a function of time for different
slag and metal compositions and temperatures. In this project a range of samples,
collected by TATA-steel, will be characterized and the importance of drops will be
elucidated. The working hypothesis to be tested will be:
 Refining occurs primarily through droplets as opposed to the bulk
slag/metal interface.
 There is a critical flight time and size beyond which droplets will not
completely equilibrate.
The work-plan would be as follows:
1. Selection of a range(s) of samples to be characterized. This would have similar
characteristics apart from the parameter to be investigated, e.g. time or height.
2. Characterization in terms of bulk and metal chemistries and droplet size(s) and
chemistries
3. Comparison to P transfer models in literature. This would involve empirical
correlations (e.g. Suito) and thermodynamic packages such as FACTSAGE.
4. Identification of the cause of disagreement in and development of kinetic equations.
With the anticipated installment of a new high temperature scanning confocal laser
microscope at WMG, real time experiment to follow a drop of given size immersed in a
slag phase can be carried out to support and validate the developed equations.
Entry Requirements
Due to funding regulations application is restricted to UK students only.
Applicants should possess a first degree of at least a second class honours standard or
the equivalent.