david wilson recarburiser product manager
TRANSCRIPT
EST. 1863
David WilsonRecarburiser Product Manager
• Introduction
• History and technical background
• Traditional materials
• Customer environment and requirements
• Market trends and new developments
• Conclusion and predictions
David WilsonRecarburiser Product Manager www.durransgroup.com
What is a Carbon raiser?
A Carbon Raiser, is a any
carbonaceous material
that is added to a
molten ferrous alloy to
adjust its melt
chemistry.
i.e. increase the
percentage of Carbon
Carbon Usage: Iron and Steel
Manufacturer of ferrous material, such as Steel works and Iron
foundries, need to adjust the melt chemistry of their molten ‘iron’
to achieve the required finished products.
Carbon a key alloying element
within iron and steel alloys
and control of this primary
relationship allows the ferrous
metallurgist to dictate the
properties of the finished
material.
It is clearly evident that ancient civilisations had a
good understanding of the metals production and
properties
However it wasn’t until René
Réaumur postulated in 1722
that the amount of carbon is
greatest in cast iron, less in
steel, and least in wrought iron.
In the second half of the 18th Century further work was
carried out by Swedish scientists Scheele, Berman and
Rinmann. They identified that the concentration of a
substance they referred to as ‘Graphite’ varied in wrought iron
(0.05 to 0.2%), Steel (0.2 to 0.8%) and Cast Iron (1.0 to 3.3%)
The French scientist Guyton de Morveau
first conceived of steel as an Iron –
Carbon alloy in 1799. Although the form
of the carbon remained a mystery.
Finally in 1868 D.K. Chernov established the existence of
critical temperature points at which transformations occur in
steel.
This led to the
modern Iron - Carbon
phase diagram
Iron - Carbon Phase Diagram
Iron - Carbon Phase Diagram
Iron – Carbon: Carbon Equivalent
To make matters more complicated other alloying elements
also act as ‘Carbon’ within iron and steel alloys. The are
numerous equations describing the relationship between
various alloying elements. For example, within cast iron the
Silicon and Phosphorus contents are critical:
CE = %C + 0.33(%Si) + 0.33(%P) – 0.027(%Mn) + 0.4(%S)
Or more simplified : CE = %C + 0.33(%Si + %P)
There are many more equations for steel alloys.
However, I will not be focusing on these today.
• So in summary, the Iron – Carbon phase diagram allows metallurgists to predict the properties of a particular Iron (Steel) alloy.
• Control of Carbon is critical in the production of Iron (Steel) alloys
Where do we fit into this industry?
EST. 1863
The James Durrans & Sons Limited was founded in 1863 in the British town of Penistone. The company has never strayed from its manufacture of foundry based, carbon-related products.
Today the group has 10 manufacturing sites. We have 4 in the UK, 2 in Germany and 1 in China. In addition we have joint ventures in France, South Africa and India.
United Kingdom
James Durrans & Sons Ltd.
Carbon International
China
James Durrans (Tianjin) Coatings Ltd.
India (JV)
MPM-Durrans Refracoat Pvt. Ltd.
South Africa (JV)
Durrans RMS.
France (JV)
Carbon International SAS.
Germany
James Durrans GmbH
Since its establishment, James Durrans & Sons Ltd. has been
at the forefront of providing carbon based products to a vast
array of industries, which include:
Steel manufacturers
Iron, Steel and Non-Ferrous foundries
Automotive, Rail and Aerospace Industries
Power Generation, Transmission and Storage
Refractory and Glass manufacturers
Telecommunications, Utilities and Water Treatment
Specialised Chemical Manufacturers
Oil and Gas production
Furnace and High Temperature equipment manufacturers
Finally something that makes
us truly unique, is our Royal
Charter issued by Queen
Victoria
Where are they used?
A tale of two industries
◦ Steel Manufacturing
◦ Iron Foundries
The requirements of the steel
manufacturing industry are quite
different for those of Iron Foundries.
Steel manufacturers are very cost sensitive.
To a large extent they are less concerned over the product’s chemical analysis.
Although cost sensitive, this is not
their prime focus.
Product chemistry and consistency
are critical to Iron foundries.
Although focusing on different aspects of
the carbon raiser they all use the same
standards by which to rate them.
Chemical Analysis
◦% Ash
◦% Volatile matter
◦% Moisture
◦% FIXED CARBON (100 – Ash+Vol+Moist)
◦% Sulphur
◦% Nitrogen
◦% Other trace elements
The concept of Fixed Carbon is an artificial one.
It is purely a calculated approximation of a products purity.
It does not take into account the presence Sulphur or Nitrogen (along with other elements).
◦Anthracite Coal
◦Metallurgical Coke
◦Calcined Petroleum Coke
◦Natural Graphite
◦Synthetic Graphite
Major benefits: Readily Available (i.e. found all around the World) Relatively inexpensive (it’s a raw mined product)
Drawbacks Qualities depend on origins, temperature and
pressure at formation Low solubility
Typical Specification
Ash 3.5 to 20.0 % Volatile. 5.0 to 9.0 % Moisture. 0.5 to 1.0 % Fixed Carbon. 65 to 90 %
Sulphur. 0.5 to 1.0 % Nitrogen 0.3 to 0.8 %
Major benefits: Readily Available (i.e. found all around the World) Inexpensive
Drawbacks Qualities depend on origins
of the coals and coking process quality.
Limited availability due to demand by other industries
Relatively low solubility
Typical Specification
Ash 8.5 to 20.0 % Volatile. 1.0 to 3.5 % Moisture. 0.5 to 1.0 % Fixed Carbon. 65 to 90 %
Sulphur. 0.8 to 1.5 % Nitrogen 1.0 to 2.5 %
Major benefits: Consistency of a manufactured product Low impurities (i.e. high fixed carbon)
Drawbacks Limited supply Qualities depend on origins
of the oils and blend quality Limited availability due to
demand from other applications
Typical Specification
Ash 0.1 to 0.5 % Volatile. 0.2 to 0.5 % Moisture. 0.1 to 0.5 % Fixed Carbon. 98.5 to 99.5%
Sulphur. 0.3 to 1.8 % Nitrogen 0.6 to 2.0 %
Major Benefits Naturally occurring around the World. High solubility
Drawbacks Limited availability due to
demand from other applications
Relatively low Fixed Carbon
Typical Specification
Ash 4.0 to 11.0 % Volatile. 2.0 to 4.0 % Moisture. 0.1 to 0.5 % Fixed Carbon. 85.0 to 92.0%
Sulphur. 2.0 to 3.0 % Nitrogen 1.5 to 2.0 %
Major Benefits Consistency of a manufactured product Very low impurities (i.e. high fixed carbon)
Drawbacks Limited availability due to
demand from other applications
High costs due to lengthy and expensive manufacturing process
Typical Specification
Ash 0.1 to 1.0 % Volatile. 0.1 to 0.5 % Moisture. 0.1 to 0.5 % Fixed Carbon. 98.0 to 99.5%
Sulphur. 0.01 to 0.10 % Nitrogen 0.01 to 0.10%
• Steel manufacturers are extremely cost sensitive (Fixed carbon per unit of currency)
• Volumes are very high, measured in the hundreds of tonnes per month
• Less sensitive to impurities
• Due to the temperatures involved, solubility is less of an issue
◦ Anthracite Coal
◦Metallurgical Coke
◦ Cal. Petroleum Coke
◦Natural Graphite
◦ Synthetic Graphite
Carbon Raisers for Steel works
◦ Ideal for bulk charge
◦ Ideal
◦ Trim additions
◦ Short supply◦ Relatively expensive◦ Trim additions◦ Relatively expensive
• Iron foundries tend to focus of consistency and chemical purity
• Volumes are can be high, measured in the truck loads per month
• Sensitive to impurities
• Solubility can be a major factor
◦ Anthracite Coal
◦Metallurgical Coke
◦ Cal. Petroleum Coke
◦Natural Graphite
◦ Synthetic Graphite
Carbon Raisers for Iron Foundries
◦ Not used
◦ Poor solubility limits use
◦ Ideal
◦ Expensive and in short
supply
◦ Ideal, but relatively
expensive
• Iron foundries fall into two groups
• Ductile (SG) Iron foundries are sensitive to sulphur content
• Grey Iron foundries tend not to be sensitive to sulphur content
Grey Iron foundries
• Tend to be more price sensitive
• Solubility and consistency (performance) is critical in a volume foundry – no time to make corrections
• Sulphur levels not critical
but ideally between 0.5
and 1.2%
Ductile Iron foundries
• Price is important, not critical
• Solubility and consistency (performance) is critical in a volume foundry – no time to make corrections
• Sulphur levels critical,
ideally < 0.1%
◦Anthracite Coal
◦Metallurgical Coke
◦Calcined Petroleum Coke
◦Natural Graphite
◦Synthetic Graphite
Looking back at the list of traditional materials:
◦Calcined Anthracite (gas or electric)
◦Pelletized materials
◦Graphitised Petroleum Coke
◦Pitch Coke
◦Bespoke blends of carbon materials
◦Organic and Reclaimed materials
In recent years additional products have gained
market share from the traditional ones:
Major Benefits Consistency of a manufactured product Readily available Relatively inexpensive Relatively low sulphur (approx. 0.2%) and volatile (<0.8%)
Drawbacks
Limited by Ash content (approx. 4.0%)
Limited by solubility
Uses
In Steelworks
Main use as a blending material
Major Benefits
Consistency of a manufactured product
Inexpensive
Relatively low sulphur & Nitrogen (approx. 0.6% for each)
Drawbacks
Limited by solubility (hard, no porous surface)
Limited available due to suitable feedstock
Uses
Steelworks
Grey Iron foundries
Major Benefits
Consistency of a manufactured product
Relatively inexpensive
Low Sulphur & Nitrogen (approx. 0.1% for each)
Drawbacks Limited by fixed carbon content (i.e. High Ash and Volatile) Limited by solubility (hard, no porous surface) Limited available due to suitable feedstock
Uses Steelworks Large SG producers
Major Benefits
Consistency of a manufactured product
High purity, low Sulphur & Nitrogen (0.05% for each)
High solubility and graphitic nature
Drawbacks Limited availability High energy production costs (2.5 MW per tonne) Environmental concerns – Sulphur emissions
Uses Steelworks SG Iron foundries
Major Benefits
Consistency of a manufactured product
Good Sulphur content (approx. 0.5%)
Good solubility
Drawbacks
Limited but increasing availability
Uses
Steelworks
Iron foundries
Many producers are now providing their customers with bespoke blends of the materials already discussed.
These benefit the customer with a seemingly ideal carbon chemical analysis. However, blends are manufactured with materials of varying solubility.
The resulting ‘jumps’ in Carbon recovery lead to an inconsistent melt practice and constant late trim adjustments.
The sheer availability of waste organic materials has led to them being used as carbon additions to ferrous metals. Crushed coconut shells and spent rice husks being the most commonly encountered.
Although these have relatively low Sulphur contents, and extremely cheap, they have very high ash levels. This translates into large amounts of unwanted furnace slag, which can become inclusions within the finished product.
Finally, reclaimed carbonaceous materials such as spent anodes and reclaimed tyres.
To date, the available materials tested have been shown to contain high volatile contents (>2.0%) and are generally inconsistent. In the case of spent anodes, there also remains concern over the potential of residual salt and heavy metal contamination.
These materials are currently not in significant use.
However, with todays focus on recycling technologies, these manufacturing processes are likely to undergo improvements.
It is difficult to predict whether these materials will have a place in the future. They are certainly not up to the required standard yet.
Carbon Raisers: (approximate values) Index: 1 = Best, 9 = Worst
Type of Carbon Fixed
Carbon
Sulphur Ash Volatile Moist. Solubilty
Index
Avail.
Index
Cost
Index
High Purity Synthetic Graphite 99.70 0.01 0.10 0.10 0.10 1 7 9
Synthetic Graphite 99.20 0.03 0.30 0.20 0.30 2 8 8
Graphitised Pet Coke 99.00 0.05 0.30 0.40 0.30 3 5 6
Low Sulphur Pet. Coke 98.90 0.10 0.40 0.40 0.30 4 6 5
Low Sulphur Pellets 98.00 0.10 0.50 1.30 0.20 6 6 4
Calcined Anthracite 95.00 0.25 4.00 0.50 0.50 6 3 6
Natural Graphite 88.30 0.10 10.00 1.00 0.70 2 7 7
Medium Sulphur Pet. Coke 99.20 1.00 0.30 0.20 0.30 5 3 4
Med. Sulphur Pellets 98.00 0.70 0.50 1.30 0.20 7 6 3
Pitch Coke 98.30 0.50 0.70 0.50 0.50 4 5 5
Metallurgical Coke 83.70 0.90 14.00 1.50 0.80 8 1 2
Anthracite Coal 84.00 0.80 10.00 5.00 1.00 9 2 1
Clearly Steel making has been in the spotlight of the media
recently. With the current excess availability of Steel, the
worlds prices have fallen dramatically.
This has clearly put pressure on all manufacturers and
therefore suppliers. However, most steel manufacturers
already utilise very low cost materials, so this already
competitive market is going to get very congested.
Iron foundries also face a very tough time which will impact
on their usage of materials.
Many are already exploring alternatives to their traditional
materials in a hope of either improving their processes
(reducing scrap), by lowering their overall costs (reduction in
time) or by helping to meet their environmental obligations.
This is good news for some …
However, most iron foundries are so short staffed that they
physically find it difficult to justify changes to the practices or
to carry out trials. This is combined with the reluctance of
their customers to accept process changes (specifically
Automotive) unless there is good reason.
New suppliers must offer the potential of significant
reductions in order to merit the workload of trials.
However, given that so many other materials are reducing in
price, the pressure on carbon (a relatively small spend) is
reduced.
So finally there is some light at the end of the tunnel.
Global oil process continue to remain low, impacting on the
cost of manufacture of carbonaceous product.
There is also increasing environmental pressure on
manufacturers to improve their output.
This will hopefully impact all.
Looking more specifically at Graphite.
Steel manufacturers seem unlikely in the future to look
towards graphite as a Carbon raiser given the price, quality
and availability of the alternative materials.
However, Graphite, or at least Graphitic materials, remain an
important go to material for Iron foundries. The technical
benefits offered by Graphite over the alternatives remain
clear, but they come at a financial cost.
I hope that I have demonstrated that the current market
place for Carbon Raisers is diverse and extremely
competitive.
Looking forward graphite, specifically synthetic graphite, is
likely to retain a small market share of the carbon raiser
sector. However this will most likely be focused on niche
markets where purity and solubility are critical.
David Wilson
Recarburiser Product Manager
James Durrans and Sons Limited
EST. 1863