Keeping scrap metal in its purest form possible has long been a problem in the metal recycling industry. With waste streams increasing in value and the market for scrap growing, it is paramount to recycle as effectively as possible in order to make the most profit. ReSteel introduces a technology which is helping things along…
by Petra Smits
It is an age-old discussion between the steel industry and its suppliers: how to keep copper contamination in scrap within acceptable limits. Even after hand-picking, the red metal can be present in unattractively high levels. This is a big problem for the steel industry because excessive contamination of the melt causes new steel to be either too soft or too brittle, making it unsuitable for its intended purpose.
For metal-scrap processing companies, particularly automobile (ELV), electrical and electronic (WEEE) and incineration scrap companies, copper contamination of ferrous scrap is becoming an insurmountable issue because it does not meet the quality standards of the steel mills.
A company called Heros in Sluiskil, Netherlands, had the same problem with contaminated scrap in the past. It solved the problem by using the ReSteel CSM (Clean Scrap Machine). Adrie Voermans, Commercial Manager of Heros, says: ‘We deal with incinerator scrap. Before installing the CSM, we needed five hand-pickers to manually remove the copper from the scrap stream. Now we need only three hand-pickers, because this machine is considerably faster than manual sorting. We are also able to extract much more copper than before, which means higher revenues. And, we are producing scrap that is entirely copper-free. The improvement of the quality we are producing is impressive. This is an investment in the future, because steel mills will increasingly demand scrap that is free of copper.’
According to steel producers, this problem undermines their confidence in scrap as a raw material. ‘The steel industry needs scrap with improved quality’, says N. Prüm of Arcelor Mittal. He pointed out that a further increase in copper concentration would rule out automotive applications for steel. He attributed the high copper content to ‘insufficient sorting’ and stated this could ‘jeopardize the future recovery of steel and the recycling business as a whole.’ Prüm added, ‘Technologies to achieve better quality should be used and further developed.’
This means if steel mills cannot use scrap in their processes anymore, they have to use natural resources (iron-ore). The result is higher costs for the factories, higher steel prices and a bad situation for the environment, because using just one tonne of cleaned scrap for steel-making instead of iron-ore consumes 75% less energy and produces three tonnes less of CO2 per tonne of steel produced. The technology ensures that ferrous scrap continues to be a vital source of raw materials. Which means conserving the world’s precious natural resources, reducing carbon emissions, and contributing to a society built upon the sustainable use of our resources.
A solution for scrap
ReSteel International develops technological solutions for the steel recycling industry. In October 2008, ReSteel was formed when private equite firm Icos Capital, a Dutch Clean-Tech Invester came-up with a funding package. Icos is the major shareholder in the initiative along with Delft University. The supervisory and advisory board members bring additional knowledge, networks and experience and the team at ReSteel includes leading scientists in separation technics from Delft University as well as experienced managers in the field of waste management. The first machine was delivered in the Netherlands in July 2009, and the company is now in contact with several big metal scrap processors globally.
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A ReSteel clean scrap machine operating on site. |
ReSteel aims to offer scrap processing companies in the European market a technological solution to escalating scrap contamination issues. The idea is to deliver clean scrap with a constant and known specification, and a reduction of copper-rich parts of more than 90%. These companies need to meet the quality standards of the steel industry, and hope to maximize the value of their scrap while increasing their processing capacity. ReSteel aims to achieve this using a technology invented by Delft University of Technology.
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Copper rich elements of incineration scrap. |
The technology
Five years ago, at Delft University of Technology’s faculty of Civil Engineering and Geosciences, Professor Peter Rem and his colleagues began extensive research into the specific properties of steel and copper and identified differences which have led to the development of new separation technology. They developed the clean scrap machine (CSM) which can lower the copper content to almost nothing. Rem was recently the recipient of an award for most entrepreneurial scientist for his contribution to the technology behind ReSteel. This technology is different from others in the market because the CSM can separate non ferrous from steel (so it is not an eddy current system) and can separate copper in an effective way.
The technology is applied in the CSM (Clean Scrap Machine), shown in Figure 1 (overleaf). The CSM divides the scrap into two separate streams. One is the so called ‘clean scrap’ which consists of 75%-85% of all the ferrous parts and is ten times cleaner than the input. Two is the so-called ‘remainder’ which is only 15%-25% of the total input and contains a high percentage of non ferrous parts and non liberated copper.
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A ‘clean scrap’ fraction produced from WEEE by the CSM. |
To specify the amount of ferrous scrap collected in the ‘clean scrap basket’ ReSteel defined the ‘clean scrap ratio’. Depending on the sort of scrap a customer needs, the average range for the clean scrap ratio is 75%-85%. To determine how much non liberated copper is collected in the ‘remainder basket’ ReSteel defined the ‘separation efficiency’.
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| The ‘remainder’ of the WEEE fraction after processing. |
Clean scrap machine
The ReSteel Solution aims to offer users:
- Quality scrap – the CSM significantly reduces the copper rate in ferrous scrap. Higher quality means higher scrap prices.
- Increased processing capacity – the CSM has the capacity to process significantly more scrap per hour than many other systems, and reduces the need for manual labour due to a reduced non-ferrous fraction.
- Consistent quality – a mechanical process that has been rigorously tested.
- No need for manual hand-sorting.
- Higher copper revenues – as it has the capacity to extract double the amount of copper rich parts.
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Figure 1: The CSM machine – the average range for ‘separation efficiency’ is typically 90%. |
Common metal recycling problems
Automobiles are the most recycled consumer product in the steel industry, with approximately 9 million tons (8.2 million tonnes) of ELV scrap produced each year in Europe (EU25).
But with an increasing number of vehicle components being built from non ferrous metals, shredder operators are dealing with ever higher levels of contaminants entering their steel fraction. The most troublesome of these is copper. Typically, ELV scrap contains copper levels of between 0.5% and 11%. Even with additional hand-sorting measures, meeting the stipulated less than 0.25% for copper in ferrous scrap is becoming a virtually impossible task.
Waste Electrical and Electronic Equipment (WEEE) is a rapidly growing waste stream that covers everything from computers to washing machines. With their largest constituents being iron and steel, nearly four million ferrous tons are extracted from WEEE scrap in Europe each year. E-scrap is a growth market – rising roughly three times faster than other forms of municipal waste. As it grows, however, so do the quantities of contaminants appearing in the ferrous scrap stream.
In Europe (EU25), approximately 1,150,000 tons (1,043,000 tonnes) of ferrous scrap are sourced from incineration plants each year. With European countries under pressure to achieve EU landfill targets, incineration – and thus incineration scrap – is a major growth market. A growing issue, however, is contamination of the scrap stream by unwanted materials found in the bottom ash of incinerators. The most troublesome of these is copper, which causes new steel to be either softened or brittle. The number of non-liberated copper elements in steel scrap has increased substantially in recent decades. Typical copper levels found in incineration scrap are now around 0.7%, well above steel mill requirements.
The ReSteel system has the capability to reduce the copper levels of ELV, WEEE and incineration scrap by at least 90%. The result is a ferrous fraction of almost pure iron, comprising no less than 75%-85% of the total scrap volume. The invention is based on a process and device for the separation of fragments of liberated ferrous scrap from non-liberated ferrous scrap fragments by means of a static magnet.
Environment
Steel and copper from ferrous scrap are materials that, when clean, can be infinitely recycled. The critical word here, however, is ‘clean’. With ever larger quantities of electrical equipment finding their way into our waste, steel and copper are becoming so interwoven that current techniques can no longer entirely separate them, rendering them increasingly difficult to recycle.
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Figure 2: The CSM divides fractions into the scrap basket and remainder basket. |
A decline in the quality of scrap steel is jeopardizing the entire scrap processing industry. This is where technology such as ReSteel comes into its own. ReSteel can ensure that scrap, as well as its contaminating metals such as copper, are separated, and thus recyclable. It’s a solution that aims for:
- More and cleaner scrap for the steel industry. The CSM makes scrap purer. This ensures that more scrap can be used as raw material for steel making – reducing dependency on iron ore.
- More copper to recycle. Worldwide around 60 million tons (54 million tonnes) of scrap that is rich in copper is produced each year (2008), containing around 400,000 tons (362,000 tonnes) of copper. Only half of this copper can be extracted using existing methods. The CSM would allow an additional 150,000 tons (136,000 tonnes) of this copper to be removed, putting more recycled copper into circulation and reducing our need for copper ore in copper production. Recycled copper produces emissions many times lower than that produced by copper ore – a saving of 1 kg of Sox per 1 kg of recycled copper.
Petra Smits is the Manager of Inside Sales, ReSteel International BV.
e-mail petra.smits@resteel.nl
