Recylcing and Recyclability
Recent initiatives by New Zealand Steel and by Pacific Coil Coaters, our primary suppliers of metallic coated and painted steel, will improve the sustainability of their operations, as reported in Scope 58 and in this issue 59, and we thought it worth revisiting an article published originally in 2008 and again in February 2015 and updating the content.
New Zealand Metal Roofing Manufacturers Inc (NZMRM), as does every industry that wants to survive, is continuously looking at the sustainability of their products and member companies. We have been operating a Sustainability Subcommittee since 2006, which looks at issues affecting the sustainability of our products and industry. It has been proactive in promoting the sustainability benefits of MRM to various external bodies, including Metals NZ and the NZ Green Building Council. We are founder members of the Sustainable Steel Council Inc.
RECYCLING and RECYCLABILITY
New Zealand Steel, in the last issue of Scope, discussed the proposed electric arc furnace (EAF) project, co-funded by the NZ Government, which will reduce their “carbon footprint” and at the same time use locally a significant percentage of the steel scrap which is currently exported. Pacific Coil Coaters, in this issue, will talk about their new electric ovens which as well as offering a more flexible manufacturing process, are already reducing markedly their own carbon emissions.
Both projects use and will use more of sustainably produced NZ electricity instead of fossil fuels and so contribute to New Zealand’s efforts to reduce our overall carbon emissions (minute though they may be by world standards).
These projects are both at the front end of the very long life of steel.
What is not always so well known about is the other end of the life of steel and indeed all metal – its ability to be recycled and its actual method and level of recycling. In fact metal used in cladding (and elsewhere of course) is able to be recycled indefinitely with no loss of quality (unlike any other material), and actually is recycled to a very high degree, not least because the processing energy cost of recycling is significantly less than that of making virgin metal. Steel scrap is worth money, not just something to be got rid of like most materials.
Steel is effectively immortal. Once made from iron ore, or in NZ, ironsand, it actually lasts forever, unchanged, and can be remade into any number of products, with its properties unchanged. While this is true of some other metals, (in the building sector of aluminium), no other material can legitimately claim this. In spite of “recycled” or “recyclable” plastic, glass, concrete and so on, all of these lose quality during the process and only exist as lower quality materials for one or two cycles before being uselessly degraded and turning into pollution.
At the end of its long life, used steel is eagerly sought after on the world market and then melted down, using much less energy than the original process, and emerges in whatever form required just like new. Since there is a world shortage of steel, as well as making new steel, the global industry consumes all the scrap it can get. Because of its long life, recycling can’t make enough to fill the demand. Such is the process that the majority of all steel ever made (since the 1820s) still exists somewhere, and will continue to live forever. Your imported steel knife may contain a very small fraction of steel made somewhere in 1850 (which of course may only have been scrapped recently).
In this article, we provide information from world sources and specifically New Zealand sources to discuss the generic recyclability and recycling of metal, in particular steel, and about the unique system and cycles operating in New Zealand. What follows has been taken from a number of sources and so is only as accurate as the sources. We deal here only with steel, which is by far the main material used for metal building cladding, but many of the comments about recycling apply equally to aluminium, certainly at world level, even though it has quite different processes. And indeed other metal cladding materials such as zinc and copper have such high value as to always be recycled.
Recycling, recyclability and reusability
It is important to separate these similar sounding operations.
As above, steel is the ultimate recyclable material. Its quality is unaffected by reprocessing and recycled steel is as good as new, but has much less embodied energy. All steel products have the ability to be recycled, but the degree to which they are recycled and the ease of doing so does depend on how much they are mixed with other materials and the difficulty of recovery from the other materials. Reuse of material similarly depends on its quality at the end of the life of whatever contains it. Structural steel is very reusable and can be recycled. Steel cladding can be reused depending on its condition (and may end up on a lower quality building) but is more easily recycled (and is much easier to melt than structural steel). Steel used as reinforcing in concrete is fairly easy to recycle although as this requires the destruction of the concrete it is difficult to recover. Steel used in motor car bodies is highly contaminated with other materials. In spite of this variability steel for recycling is a valuable resource and 85-90% of steel used in construction is recycled globally. Over 60% of all steel used globally is subsequently recycled. One source (The World Counts – very interesting) says over 1 billion tonnes of steel is recycled annually; even in NZ we are talking of up to 500,000 tonnes of scrap p.a.
The ability to be recycled
A number of common materials can be recycled in the sense of being taken in a form which is no longer needed or able to be used and then converted into something else. A number of products themselves are able to be reused once the item into which they are incorporated is no longer required.
Metals in various forms, glass, plastics, paper, timber, fabrics and others are able to be reused in some way, and we are all familiar with the recycling programmes of local councils – unheard of 20 years ago but now common – in which various materials are left outside to be “recycled”. We have the idea that they are reused in some way without being very aware of what this might be. For a number of materials collected in this way recycling is actually not possible currently. In fact, to varying degrees nearly all these – apart from metals – are either not actually reused in a recognisable way or are degraded during reprocessing from the original form or quality (often referred to as “down cycling”). Nearly all non-metals even if reused as part of a new or similar product are in a product of lower quality or value with reduced physical or aesthetic properties. The current term “Recyclable” often seen on plastic packaging is really a rather cynical marketing ploy to make you think that the product will actually be recycled as is. While much packaging could actually be reused the cost of cleaning it means this never happens. Remember glass milk bottles (maybe many of you can’t!) but these were a valued product, washed and put out daily in order to get a new one. These were then machine washed and refilled with milk. No longer. Much “recyclable” product ends up in land-fill or on a beach in Malaysia.
Metal and specifically steel cladding (which after all is what we (NZMRM) make and sell) can both often be reused in the original form but more importantly it can be recycled into product indistinguishable from the original, totally undegraded and capable of being recycled indefinitely. Steel cladding is generally unmixed with anything other than metal coating and paint and has thin sections and so is one of the most easy to recycle steel products, compared with e.g. reinforcing steel buried in concrete.
Throughout its history steel has always been recycled and all steel contains a proportion of recycled material from 10 – 100%, so that any steel currently in use actually has some content that may have been used a number of times.
Recycling levels
Because of the factors discussed above - and below – (no loss of quality, scrap required for efficient function of steel mills, much lower energy content), steel has a very high level of recycling – typically up to 90% of all steel embodied in buildings and in artefacts which have ended their useful life ends up being recycled into fresh steel ready to start as good as new, into a long new useful life.
In the case of building cladding, quite a lot can actually get reused (rather than recycled as material) although generally in a lower value role – e.g. steel roofing from an office might end up in a fence or a farm shed. The actual percentage of steel which is recycled obviously depends on the application, so that steel which can be reused when a building is taken down is different to steel in a crushed motorcar body or an old fridge, but overall it is very high. According to one source this is 60% of steel globally.
Steel manufacture and recycling
Today, steel is nearly all made by one of two processes world-wide.
The Basic Oxygen Furnace (BOF) is the main method for converting iron made from iron ore into steel. It needs to use some recycled steel for efficient running and will use from 10-25% of recycled material.
This may be in-plant scrap (“pre-consumer recycle” or “home scrap”) or bought-in scrap metal that is derived from steel items past their usefulness (“post-consumer recycle”). Typically a BOF unit will use all its own in-house scrap and some bought-in material.
The Electric Arc Furnace (EAF) can also convert iron into steel but is the main way of consuming scrap steel materials (post-consumer), and the process requires a minimum level of at least 30% scrap to function. EAF units can run from 30 to 100% scrap. A number of mills with EAF only use scrap steel as a raw material. About 30% of all steel comes from an EAF, limited by supply.
Because steel is a durable material and is used mainly in quite long-life products (unlike packaging materials) and is also in increasing demand, the amount of scrap available (even at very high recycling rates) is not sufficient to feed the demand and so virgin steel continues to be made from iron ore (or ironsand). Many global steel companies have both types of furnace and are able to take in and reuse large amounts of scrap steel – typically as much as they can get, because reprocessing scrap steel requires less energy than making new steel.
Globally then, steel mills making all sorts of steel products use both recycled (pre- and post-consumer scrap) and virgin iron made from iron ore. The proportion varies from mill to mill; some only use scrap and others use smaller amounts of it in their mix. Overall a very high level of recycling is achieved (60% apparently).
The New Zealand scene
New Zealand Steel (now part of Bluescope Steel, an Australian manufacturer) started manufacturing steel at Glenbrook (approximately 60km south of Auckland, the biggest market) in 1963. After many decades of research, a process had been developed to process the local ironsand in a unique process that has a small ecological footprint compared with transporting rocks for sometimes thousands of kilometres, and the Glenbrook plant was built to use this process.
When this author first visited Glenbrook in 1984 they had two EAFs used to make steel from iron. After various changes in technology (and ownership) New Zealand Steel now uses the BOF process and makes all new steel from iron with only about 12% in-plant waste (pre-consumer scrap) added.
Now work is in hand to convert NZ Steel back to EAF for steel production, which will allow (indeed require) greater percentages of steel scrap from local external sources and allow significant reduction in export of scrap, which is a waste of a valuable resource.
Use of scrap steel in New Zealand
Home scrap (also known as circulating or internal scrap) is the residue left from the steelmaking, rolling and finishing operations and includes croppings, offcuts and material rejected by quality inspection procedures. This internal scrap usually accounts for about 10% of total crude steel production in an integrated steelworks. Currently NZ Steel uses the BOF process which can use a maximum 20% of scrap in its metallic charge. Thus NZ Steel uses only its own “home scrap” in its steelmaking process. No post-consumer recycle (PCR) is currently used at Glenbrook as is this not needed in the current steel-making process.
The Pacific Steel company was founded by what became the Fletcher Group about the same time as NZ Steel to produce steel reinforcing, wire, and other products primarily from steel scrap. In 2015 it was acquired by NZ Steel and started using virgin steel from NZ Steel to make higher quality products.
So from then on until now, no significant amount of scrap steel was processed in New Zealand, and all steel products were made from new steel made from ironsand, and all scrap was exported.
This will change (Back to the Future) when NZ Steel again uses an Electric Arc Furnace to produce steel from both ironsand and much of New Zealand’s currently exported scrap steel. Our sustainable credentials will be greatly improved when this happens.