david wilson recarburiser product manager

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: 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


Ash 8.5 to 20.0 % Volatile. 1.0 to 3.5 % Moisture. 0.5 to 1.0 % Fixed Carbon. 65 to 90 %


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


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%


Major Benefits Naturally occurring around the World. High solubility

Drawbacks Limited availability due to


Relatively low Fixed Carbon

Major Benefits Consistency of a manufactured product Very low impurities (i.e. high fixed carbon)

Drawbacks Limited availability due to


High costs due to lengthy and expensive manufacturing process



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


◦ 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


◦ 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


◦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


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


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


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

david wilson recarburiser product manager

Documents