1. European Union

For over 25 years, despite the general use of slag products in construction, there has been an on-going argument about whether slag is a waste or a by-product. Still today, the situation concerning the classification of slag is not uniform within European member states. In various countries some of the slag types are considered as by-products; however in others they have a waste status.

Before the revision of the Waste Framework Directive – WFD – (Directive 2008/98/EC) in 2008, there was no definition of by-products in European legislation. The WFD now allows for a clear definition of criteria characterising a by-product as well as a material that shall cease to be regarded as waste and finally becomes a useful product.

Ferrous slag placed on the market meets the requirements of national as well as European harmonised standards and specifications related to both technical and environmental aspects with regard to the intended use. For this reason, the European steel and slag industry considers slag to be a by-product.

In order to support the standardisation work of the EU Commission and in this respect to express the opinions of the European steel industry, its affiliates and downstream users, EUROSLAG (the European Slag Association, a body for the promotion of slag producers’ interests in the EU and member countries) frequently elaborates position papers. In 2006, a position paper “The legal status of slag” was written, where arguments and applied measures were summarised to demonstrate that slag is produced parallel to steel as a product (and not as waste.) It was stressed that slag that is intentionally generated by controlling and modifying its composition, its cooling conditions, its physical properties, etc., has to be accepted as a product.

The European Regulation No. 1907/2006 for Registration, Evaluation, Authorisation and Restriction of Chemicals (REACh) was adopted by the European Parliament and the European Council in December 2006 and came into force on 01 June 2007. The European Chemicals Agency (ECHA) manages the technical, scientific and administrative aspects of the REACH system.

The REACH regulation replaces a number of national regulations and directives with a single system. Just after implementation of the REACH regulation, the members of the FEhS-Institute (monitors and tests industrial by-products, e.g. ferrous slag, and other construction products and certifies their manufacturers) and EUROSLAG initiated – in agreement with EUROFER (the European Steel Association) – the registration of iron and steel slags as substances. Assuming that slag in general is not a waste but a by-product or product/secondary raw material, in 2009 the REACH Ferrous Slag Consortium (RFSC) was founded to prepare the registration of ferrous slag before 01 December 2010.

During the registration process the available data on slag compositions and corresponding production processes from all European countries were evaluated and intensively discussed. It was agreed to register all slag types as UVCB substances (Substances of Unknown and Variable composition, Complex reaction products or Biological materials) that are best described by their production processes. Other identifiers are the most frequently found mineral components and, as additional information, the chemical composition.

At the end of 2010, the registration was successfully filed by RFSC members, which altogether represented 97% of the European steel production at the time.

Key EU Statistics

Production of blast furnace slag in 2010: 23.5 million tons (Data from A, B, FIN, F, D, I, L, PL, E, SK, S, NL, UK)

Use of blast furnace slag in 2010: 25,6 million tons (Data from: A, B, FIN, F, D, I, L, PL, E, SK, S, NL, UK)

Production of Steel slag in 2010: 21.8 million tons (Data from: A, B, DK, FIN, F, D, GR, I, L, PL, RO, E, SK, SLO, S, NL, UK)

Use of Steel slag in 2010: 22.3 million tons (Data from: A, B, DK, FIN, F, D, GR, I, L, PL, RO, E, SK, SLO, S, NL, UK)

2. United States

For decades the principal use of slag in the US was as rail track ballast. AS quantities grew new applications were sought, and one that proved immediately valuable was in the building of military roads in WWI. By 1918, the year the US National Association of Slag was founded, the annual production of slag had grown to 20 million tons.

The Association was formed with the objective of promoting the use of slag, and today millions of tons of slag aggregates are used in the country. The Association and its members are constantly researching new applications for slag.

Slag has been successfully used in various projects, including the Detroit Metro Airport parking garage constructed in 2000-01; “white-topping” thin concrete road overlays in Southeast Michigan; the I-70 through Colorado’s Glenwood Canyon, where the asphalt mix had to withstand harsh conditions of weather and traffic; the Chicagoland Speedway, where slag was specified because it does not shine, giving the track skid-resistance and grip that are so important when drivers are travelling at over 300 km/h; in farming as a liming agent for adjusting the pH balance in the soil.

The Federal Highway Administration, Transportation Research Board and the various state departments of transport publish technical guidance reports on the use of slag as a road aggregate.

According to the US Geological Survey, data on US slag production are unavailable, but it is estimated to have been in the range of 18 to 25 million tons in 2013. Domestic US sales in the same period amounted to an estimated 17 million tons, valued at about US$290 million (fob plant). Blast furnace slag accounted for about 45% of the tonnage sold and had a value of about US$225 million; nearly 85% of this value was from sales of granulated slag. BOS and EAF slag accounted for the remainder.

Slag was processed by nearly 30 companies servicing active iron and/or steel facilities or reprocessing old slag piles at about 120 sites in 32 states; included in this tally are a number of facilities that grind and sell ground granulated blast furnace slag (GGBFS) based on imported unground feed. Prices per ton ranged widely in 2013 from a few cents for some steel slags at a few locations to about US$100 for some GGBFS

Air-cooled iron slag and steel slag are mainly used aggregates in concrete (air-cooled iron slag only), asphaltic paving, fill, and road bases; both slag types also are used as a feed for cement kilns. Almost all GGBFS is used as a partial substitute for Portland cement in concrete mixes or in blended cements.

Pelletized slag is generally used for lightweight aggregate but can be ground into material similar to GGBFS. Owing to their low unit values, most slag types can be shipped by truck only over short distances, but rail and waterborne transportation can be longer. The much higher unit value of GGBFS allows this slag to be shipped economically over longer distances.

Slag is commonly returned to the blast furnaces as ferrous and flux feed, but data on these returns are incomplete. Entrained metal, particularly in steel slag, is routinely recovered during slag processing for return to the furnaces, but data on metal returns are unavailable.

Recent data indicate that GBFS (mostly unground) is the dominant type of ferrous slag imported, but official import data include significant tonnages of non-slag materials (such as fly-ash and silica fume) and slags or other residues of various metallurgical industries (such as copper slag). Based on official data, the principal country sources for GBFS were Canada (40%), Japan (40%), Italy (7%) and South Africa (7%).

The availability of blast furnace slag is becoming problematic because of the decline in the number of active blast furnaces in recent years, the lack of construction of new furnaces, and the depletion of old slag piles. Recent draft regulations to restrict emissions (especially of mercury) from US cement plants and to potentially reclassify fly-ash as a hazardous waste for disposal purposes have the potential to limit the supply of these cementitious materials to the market and could lead to an increase in demand for GGBFS.

Although world slag data are unavailable, the USGS estimates that world iron slag output in 2013 was of the order of 260-320 million tons and steel slag about 170-250 million tons, based on typical ratios of slag to crude iron and steel output.

3. Australasia

The Australasian (iron and steel) Slag Association was formed in 1990, with a model similar to the US National Slag Association. The ASA represents producers, processors, marketers, customers and suppliers of iron and steel slags across Australia, New Zealand, Indonesia and Malaysia.

The ASA conducted a benchmarking study in 2010 into the energy use associated with EAF S, potential end-use applications and attitudes and issues impacting on the effective utilisation of EAF S in Victoria. Key details to emerge from this report were:

• Limited volumes were effectively utilised at the commencement of the program;
• EAF S was poorly understood; moreover, Vic Roads held negative perceptions initially. EAF S were not addressed or specifically allowed for in key material specifications;
• There were insufficient projects and case studies demonstrating the environmental and performance characteristics of EAF S to provide confidence to Vic Roads;
• Local government were identified to be technically risk-averse to new products, they default to Vic Roads specifications and approved products;
• For the period, 3.4 million tons of iron and steel slag products were produced within Australasia (Australia and New Zealand) Of this 80% was effectively utilised (sold or reused for some beneficial use)
• 20% was used in cementitious applications (high value add, i.e. more than A$100/ton)
• 48% was used in non-cementitious or road construction applications (medium value add, i.e. A$10-100/ton)
• 12% was used in general civil or fill applications (low value add, i.e. less than A$10/ton)

4. Japan

The Nippon Slag Association (which was founded in 1978 by 20 steel manufacturers and manufacturers and sellers of iron and steels slag products) carries out business activities for the purpose of promoting a broad understanding of iron and steel slag products among consumer industries, governments, and academic associations, and for purposes of effective use of these products. This involves

• Conducting investigations and research concerning iron and steel slag product quality and technologies; and
• Collecting information related to production, supply, and demand of iron and steel slag products and promoting the use of these products.

Manufacture and quality management of iron and steel slag products are carried out according to their application. The majority of these products are provided to the market either as JIS (Japan Industrial Standard) equivalent products or as designated procurement items under the Green Purchasing Law.

Many iron and steel slag products have been highly rated for their superior environmental performance and record of use over many years, and have been included as “designated procurement items” (products that contribute to reducing environmental impact) for public works under the Law Concerning the Promotion of Procurement of Eco-Friendly Goods and Services by the State and Other Entities (Green Purchasing Law) which took effect in 2001.

Based on Law on Promoting Green Purchasing, national and local governments are actively working for procurement of these materials, and they are being utilised effectively as materials for civil engineering works in all parts of Japan. As a result, approximately 70% of all iron and steel slag products sold domestically in fiscal year 2007 were used in products that are designated procurement items.

The national government organises, analyses, and provides information related to environmental products. It also establishes types of environmental products and standards, and designates products that meet these standards as designated procurement items:

• Green purchasing is mandatory for the national government and independent administrative corporations;
• Basic policies related to procurement of environmental products must be formulated by the national government and other bodies;
• The creation of objectives for purchasing of environmental products is also mandatory;
• Public disclosure of the general procurement results is required;
• Local public agencies are also required to make efforts to promote the procurement of environmental products (formulation of policies, establishment of objectives, etc.)

For companies, the requirements of the ISO 14001 environmental management system include matters related to green purchasing, and are promoting green purchasing among organisations that have acquired ISO 14001.

In 2013 Japan produced 25.2 million tons of Blast Furnace slag. Of this, 3.8 million went into roads, 18.6 million into cement, 88 000 into soil improvement, 466 000 into civil engineering and 186 000 into concrete aggregate.

In the same period 14.4 million tons of steel slag was produced. Of this, 2.5 million went into recycling, 5.2 million into roads, 566 000 into cement, 879 000 into soil improvement, 5.4 million into civil engineering and 147 000 into outside recycling.

Over the weekend encouraging news emerged from the South African department of energy regarding increasing investment in renewable energy projects spanning wind, solar and photovoltaic. Better late than never.

One hopes that these projects will have an accelerated time-frame so that they can sooner contribute to the energy shortfall and reduce the country’s climate impact.

There seems also to be a firm resolve to forge ahead with fracking in the Karoo and with the massive nuclear build programme. As much as I think both have merit, I hope the decisions to move forward in both cases are based on solid research and that the cost-benefit analyses are sound. The country can ill afford any mucking around.