Position Paper on the Status of Granulated Blast Furnace ...projects.gibb.co.za/Portals/3/OSHO Cement Position Paper.pdf · Position Paper on the Status of Granulated Blast Furnace
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Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
Position Paper on the Status of
Granulated Blast Furnace Slag as a Product
April 2013
Assistant Project Manager
Danielle Welgemoed
www.oshoventures.com
danielle@0shoventures.com
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
Table of Contents
1. Introduction
a. Blast Furnace Slag
i. Production
ii. Granulated Blast Furnace Slag
b. Value
c. Uses
i. Cement
ii. Concrete Aggregate
iii. Road Binder
iv. Soil Improvement
v. Civil work
d. GBFS as a commodity
e. Benefits
i. Environmentally sound
ii. Decreased porosity
iii. Decreased thermal stress cracking
iv. Greater resistance
v. Increased durability
vi. Improved concrete workability
vii. Improved compressive strength
viii. Does not contain carbon
f. Environmental Impact
2. South African Legislation
a. NEMWA
b. Definitions
c. Objectives of NEMWA
d. Interpretation
e. GBFS as a non-hazardous material
3. International Standing
a. The Basel Convention on the Control of Transboundary Movements of
Hazardous Wastes and their Disposal of 1989
b. Europe
c. International Legal Precedent
4. South African Cement Industry Opinion
5. Conclusion
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
Consulted Resources
List of Figures
Figure 1: The production of Blast Furnace Slag (NSA, 2013)
Figure 2: Blast Furnace Slag Production Process (Nippon Slag Association, 2013)
Figure 3: Granulated Blast Furnace Slag (NSA, 2013)
List of Tables
Table 1: Present status of GBFS in European countries.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
1. Introduction Granulated Blast Furnace Slag (GBFS) is a non-metallic product consisting of essentially silicates
and alumina-silicates of calcium and other bases that is developed simultaneously, in the
molten condition, with iron in a blast furnace. The Blast furnace is the primary means for
reducing iron oxides to molten, metallic iron. Once the molten iron collects at the bottom of
the blast furnace and the liquid slag floats on it, both the Iron and the liquid slag are tapped
from the furnace. The slag is then solidified and granulated by means of specialized methods
and used in a variety of markets.
Figure 1: The production of Blast Furnace Slag (NSA, 2013)
The use of slag dates back to more than 2000 years ago when the Romans used it in order to
construct roads, evidence also exists to show that the Germans utilized Blast Furnace Slag as far
back as the late 1580’s in order to make cannon balls. The first slag roads to be built in the UK
and US dated to 1813 and 1830 respectively (NSA, 2013). This illustrates the long standing
demand for the product as well as the multitude of applications for a versatile product like Blast
Furnace Slag.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
There are a variety of slags that are produced in modern times. These include:
� Iron Blast Furnace Slag
• Air Cooled Blast Furnace Slag
• Granulated Blast Furnace Slag
• Pelletized Blast Furnace Slag
� Iron Blast Furnace Slag
• Basic Oxygen Furnace Slag
• Electric Arc Furnace Slag
� Other Slags
• Foundary Slag
• Cupola Slag
• Ladle Metallurgical Furnace Slag
The following chapters will discuss Blast Furnace Slag (BFS) with special focus on Granulated
Blast Furnace Slag due to its importance to the cement industry. The paper aims to illustrate,
through the examination of legislation, as well as national and international precedent and
trends, that Granulated Blast Furnace Slag is a product that is produced in parallel to another
product, Iron.
a. Blast Furnace Slag
As briefly mentioned in the introduction, Blast furnace slag is produced when iron ore or
iron pellets, coke and either limestone or dolomite is melted together in a blast furnace.
The details of production will be further explored in the below.
i. Production
Historically, the steel production process was only designed to produce iron and steel,
the slag generated from the process had to be used as is. However, today the high
demand for BFS has changed this, production of steel is also aimed at the generation of
high quality BFS to be sold on the open market as a variety of products.
In order to produce Iron and BFS, either iron ore or iron pellets are melted together
with a mixture of coke and limestone or dolomite. This is also known as thermo-
chemical reduction. When the smelting is complete the limestone or dolomite has
been chemically combined with the aluminates and silicates of the ore and coke ash to
form a non-metallic product, namely; Blast Furnace Slag, in parallel to the molten Iron.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
This process results in the BFS composition of primarily Calcium, Magnesia, Silica, and
Alumina.
The volume of BFS and Iron produced is dependent on various aspects including the Fe
content of the ore as well as the number of other products added to enhance the iron
and BFS, but is often a ratio of 50% iron and 50% BFS.
As illustrated in Figure 1 in the previous chapter, once the smelting is completed the
molten Iron and liquid BFS collects at the bottom of the furnace. The BFS floats on top
of the molten Iron and is tapped from the furnace in order to extract it.
Figure 2: Blast Furnace Slag Production Process (Nippon Slag Association, 2013)
Once extracted from the furnace in a molten state, the BFS can be cooled in a number
of ways, each of which produces a different type of slag. Granulated Blast Furnace Slag
(GBFS) is produced by utilizing water to rapidly cool down the liquid Blast Furnace Slag,
and is then further processed through a screening and crushing plant.
As can be deducted from the production process, BFS is generated in a parallel route to
the main hot metal production processes, so the intention of the steel producer is to
control and regulate the BFS quality by several measures during production and
processing. BFS producers are consistently aiming to improve the quality of BFS to
meet the requirements of the market.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
Figure 3: Granulated Blast Furnace Slag (NSA, 2013)
Globally most Blast Furnaces have granulation plants to produce a sought after product
- GBFS. After the liquid BFS is tapped off from the Blast Furnace, and rapidly cooled by
the addition of water, it is fed into a granulation plant. During the granulation process
the crystalline structure of the calcium silicates is altered. This enhances the
cementitious properties of the GBFS. This illustrates the continuous integrated
production process followed to produce a high quality product that is in demand.
The consumers of BFS are required to not only use a quality product with the right
composition for the benefit of their own production processes, but also because the
BFS market and specifically the GBFS for cement production is regulated by various
international as well as national pieces of legislation, guidelines and agreements. In
South Africa the relevant standard for GBFS composition, if used in cement production,
is SANS50197 or SABS EN 197-1:2000. SANS50197 stipulates the suitable/acceptable
composition of GBFS to be used in cement manufacturing.
Steel and BFS producers alter the production processes and add various additives in
order to improve the BFS that it produces; furthermore, most steel producers invest in
Granulation Plants in order to produce a high quality product for the cement industry.
The production process measures implemented in order to increase the quality of BFS
include:
• Selection of raw materials to be used in the production process based on the
chemical composition of the final Blast Furnace Slag product.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
• Influencing the production process to achieve special chemical compositions
keeping in mind the requirements of final use of GBFS ( for example in cement
manufacture)
• Specific treatment processes (soft/rapid cooling, addition of materials) are
performed to influence the properties of Blast Furnace Slag in order to adhere to
relevant requirements
• Modification of Blast Furnace Slag physical properties by crushing, sieving and
milling to achieve specific grain sizes
ii. Granulated Blast Furnace Slag
As discussed in the previous section Granulated Blast Furnace Slag (GBFS) is
produced by rapidly cooling the BFS by means of large quantities of water; this
produces a sand-like granule with glass like properties.
The GBFS is used in various applications; these include, but are not limited to:
• Grinding of GBFS to produce slag cement
• Utilisation of GBFS as an aggregate in construction
• Raw material in the production and manufacture of Portland Cement
• Raw material for utilisation in the production of glass
GBFS has proven to be a valuable material addition in the Cement Production
Process. GBFS can be used as a supplementary raw material addition to the
feed that is fed into a kiln to produce cement clinker. GBFS can also be used as
a grinding aid in the cement grinding and finishing process, this produces slag
cement. b. Value
Wide spread research and development, by producers of GBFS in the iron and steel
industry, has managed to transform the product into various modern industrial products
which are effectively and profitably used in a multitude of applications.
GBFS is sold on the international open market and the price of the product fluctuates
according to the international market demand fluctuations. Standard practice in the BFS
industry is to put in place long term commercial off-take contracts. These contracts are
based on the characteristics of the product and the value to the buyer for use in its
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
processes. They are not based on the discard of waste as steel makers are paid for the
product. Steel makers enter into long term commercial contracts with blast furnace slag
processors or consumers with the intention of exploiting the commercial value of blast
furnace slag.
The producers of steel and GBFS take action to modify the GBFS compositions based on
the requirements and offer a very high quality product to their clients (UK Environmental
Agency, 2013). The ever-growing slag market plays a vital role in the steel industry
viability, and it is widely believed that the steel industry would not be as competitive
without the slag sales that contribute to its feasibility. This is illustrated by the fact that in
some countries the proportion of cement that contains granulated blast furnace slag is as
high as 80% (EuroSlag, 2006).
Therefore it is clear that steel producers intend to regulate and control the slag that they
produce in parallel to iron. By producing quality slag products that comply with the
market requirements, producers are able to take advantage of the growing demand for
BFS as well as increase the profitability of the steel industry.
Another indication of the value and extent of the slag industry is the existence of
standards and specifications regarding the chemical and physical characteristics of the
produced product. As mentioned above, slag producers voluntarily control and alter the
chemical and physical characteristics of slag by operations/ treatments executed prior to
or during the parallel production process. Producers employ these measures in order to
fulfil all the national and international legal and buyer specific requirements.
c. Uses
Slag has a wide variety of uses. These depend upon the type and quality of slag in
question. However as the aim of this paper is to focus on the status of Granulated Blast
Furnace Slag (GBFS), the uses of the aforementioned slag will be investigated further.
i. Cement
Globally the major consumer of GBFS is the cement industry. Of the common slag
types, it is only GBFS that is of high enough quality to be used in cement. Relative to
the other types of slag, GBFS is expensive to produce, and cement is the highest value
producer, thus the two complement each other. Due to these factors, GBFS will
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
typically only be used in cement production; however if the steel industry finds itself
in over supply of GBFS it can be used in other processes.
ii. Concrete aggregate.
Aggregate is combined with cement in order to form concrete. Any variety of slag that
does not contain hazardous materials makes excellent aggregate, and this includes
GBFS. Concrete aggregate is the second biggest consumer of GBFS by volume (Lewis,
1992). GBFS has cementitious properties which make it more effective than traditional
aggregates.
iii. Road Binder
As previously mentioned GBFS is a substance with highly Cementitious properties, an
attribute that makes it exceedingly useful in the construction of roads. During
construction, layers of aggregate are laid out prior to the surfacing of the road with
tarmac or concrete. GBFS is added to the aggregate, and serves to bind the layers. This
strengthens the foundation while remaining a relatively low cost.
iv. Soil improvement
GBFS can be used as a stabilisation agent for soil. Soil stabilization involves the
addition of hydraulic binders to weak soil such that it may be improved. GBFS acts as a
binder (Britpave, 2004). Strengthening soil such that it may be used as filler in the
construction industry (Yadu et al, 2013). GBFS is particularly useful with regard to high
sulphate soils in which other stabilisers cannot be used. Stabilising soil is both a cost
effective and environmentally friendly way of allowing soil that would otherwise need
to be disposed of to be used in construction (Britpath, 2004).
v. Civil work
Large scale civil construction projects often require large scale fillers, such as an area
between two dam walls. GBFS can be used as filler and will be poured between the
walls.
Internationally the cement industry dominates the market for GBFS use, followed by the
concrete and civil industry. GBFS is used successfully in cement due to the fact that slag is
of sufficient quality to successfully improve the quality of cement. There are numerous
additional uses for GBFS, including the creation of glass wool (an insulation material), pipe
bedding and rail track ballast.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
d. GBFS as a commodity
Slag can be considered a commodity due to the product being sold on the competitive
open market, the prices and volumes fluctuate over time as the market demand
fluctuates. Demand for the product is so high that it is difficult to procure in some
locations. Currently in Japan, for example, there is no extra availability of GBFS as all that
is being produced has been committed to contracts. This serves as a clear indication of its
value as a product in various applications. In 2010, the market for ferrous slag was
estimated to reach $28 billion by 2020 (Smithers pira, 2010). In comparison; Businessmax
reported that the Oilfield Chemical market 2014 and the global market for sustainable
products was $27 billion in 2012. This clearly indicates the value of the product; and an
assumption can be drawn that the value of the market clearly indicates a high value
product rather than a waste.
e. Benefits
The GBFS product quality is heavily regulated and the requirements of the cement
industry for use of GBFS in their processes are strict; refer to SANS50197. This has
resulted in the steel industry producing uniform products. A global near uniform product
is to the benefit of GBFS consumers; whether the buyer buys GBFS from Turkey or China,
the producer will more often than not produce a product with a very similar composition,
and if not the producer will alter its production process to produce a product that will
fulfil the requirements of the client.
The utilisation of GBFS in the cement production process has shown GBFS to have a
positive impact on the strength of the cement. Strength tests are regularly conducted at
various time intervals. At 28 days slag cement shows a higher strength than conventional
Portland cement in concrete mixtures, therefore the addition of GBFS improves the
quality of the cement product to be offered to consumers (Cramer et al, 2007).
i. Environmentally sound
Environmentally the use of GBFS in the production and manufacturing of cement is
the more sustainable and environmentally responsible choice, and has various
environmental benefits. Utilising GBFS reduces the consumption of natural resources
as the alternative raw materials are virgin materials which need to be mined for the
purpose of cement production; these include limestone and gypsum. Utilising GBFS
also reduces CO2, NOx and SOx greenhouse gasses released into the atmosphere due to
the decrease of reliance on clinker in the process (NSA, 2013).
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
In motivation of the above mentioned environmental benefits The American Iron and
Steel Institute stated that; “The recovery and reuse of slag conserves tens of millions of
tons per year of other natural resources.”
In 2009 the US National Slag Association presented a presentation on Slag as a Green
Product, one of the sections highlights the US Green Building Council (USGBC), a non-
profit organization that is made up of companies and organizations from every sector
of the building industry. The USGBC promote buildings that are environmentally
responsible, healthy and profitable. In 1998 the USGBC established the LEED
(Leadership in Energy and Environmental Design) program. It is a third party
certification program and the US accepted benchmark for the design, construction and
operation of high performance green buildings. The LEED program aims to identify
environmentally friendly products to be utilised during construction. GBFS is a
recognized industrial co-product under the LEED program.
ii. Decreased porosity
GBFS is highly Cementitious due to its crystal structure and chemical composition; the
fines helps improve reactivity and this creates less porous cement. This results in less
seepage into the cement, which in turn increases the durability as the cement is less
susceptible to corrosion.
iii. Decreased thermal stress cracking
As cement heats and cools, it expands and shrinks, which can lead to micro cracks.
Over time, these can expand to damage the structural integrity of the cement. This
process, while lengthy, decreases the lifespan of concrete. The use of GBFS in cement
decreases the occurrence of cracking due to thermal stress, thereby increasing the
lifespan of concrete.
iv. Greater resistance
Blast furnace slag cement has a higher resistance to acid and sulphate attack, as well
as to chloride ingress. This reduces the risk of alkali-silica reactions with aggregates.
This will be particularly useful at the coast and aid in increasing the lifespan of the
cement (SCA, 2002).
v. Increased durability
Concrete has a limited lifespan before it succumbs to decay as a result of ongoing
environmental process. GBFS increases this lifespan due to its greater overall
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
compressive strength and resistance to acid and sulphate attacks. Blast furnace
cement has the additional advantage of being more predictable in its wear patterns in
this regard due to being of a uniform resilient nature (NSA, 2013).
vi. Improved concrete workability
The workability of concrete is based on how easily it can be poured and molded into
the desired form. Concrete with a high degree of workability will not only pour and set
easily, but will also do so without spaces, bubbles or other impediments that would
serve to damage the structural integrity of the concrete. The use of GBFS in
manufacturing of cement improves the workability of concrete (SCA, 2002).
vii. Increased compressive strength
Strength tests conducted at 28 days show that the GBFS Cement has a higher strength
than ordinary Portland cement (Cramer et al, 2007).
viii. Does not contain carbon
Carbon in cement decays, and this releases gas into the environment. In cement,
decaying carbon is responsible for air bubbles in cement. Even though they are
minute, they can damage structural integrity due to cement requiring a uniform
compression structure. GBFS, unlike rival extenders such as fly ash, does not contain
carbon, which leads to greater concrete uniformity and strength.
f. Environmental Impact
GBFS slag cement is considered to be the greenest of cements. The use of GBFS reduces
the pressure on South African resources as it eliminates some of the need to exploit
natural resources and produce new extenders by utilizing an existing product.
One of the most common extenders used in cement is limestone. For limestone to be
utilized, it must first be mined, a process that results in environmental damage through
quarrying. Mining or quarrying has negative impacts on the environment and it is
therefore preferred to use existing materials rather than exploit natural resources.
Quarrying and processing of the limestone also has a detrimental effect on the air quality
as both quarrying and crushing the limestone release limestone dust into the air. The
energy consumed for quarrying and crushing results in indirect environmental damage
through the consumption of fossil fuels. In addition, there are numerous other potential
forms of pollution, such as noise, surface and groundwater pollution. Another potential
problem created by the use of limestone in cement is the consumption and depletion of
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
natural resources. South Africa is not endowed with significant limestone deposits, and
once used these cannot be replenished.
GBFS is a cementitious product; therefore its use in cement does not decrease the final
strength of cement by weight. Rather, as mentioned in previous sections, it has been
demonstrated to actually increase the strength of cement as measured beyond a standard
28 day setting time (SCA, 2013). Higher strength cement requires less usage in concrete,
which will have clear implications for environmental savings. Limestone is not
cementitious, meaning that the volumes of cement required will effectively be raised
(Cramer et al, 2007). Considering the status of cement as a high volume product, the
national replacement of limestone cement by blast furnace cement could translate into
millions of tons of savings of cement per year. The environmental implications of this
would be immense (SCA, 2013).
At the 8th
CANMET/ACI International conference on fly ash, silica fume, slag and natural
pozzolans in concrete Jan R. Prusinski et al (2006) presented a paper on the Life Cycle
Inventory of Slag Cement. They found that the use of slag cement as a partial replacement
for Portland cement significantly reduces energy consumption, CO2 and other emissions
to the air. The report further found that slag cement reduces the energy demand with
between 21.1 and 48.4% when compared to the demands for ordinary Portland cement.
The investigation also found that slag cement results in a CO2 emissions saving of 29.2 –
46.1% as well as a virgin material saving of 4.3 – 14.6%. The findings of the report once
again illustrate the substantially lower impact the use of slag cement will have on the
environment (Prusinski et al, 2006).
Another environmental benefit of GBFS comes through its colour. GBFS is the lightest in
colour of the major cement extenders, being close to white. Most cement is used in cities,
which are subject to the heating effect of created by an urban heat island. Urban
environments have more surfaces that absorb heat (such as buildings and roads). Lighter
buildings and roads will reflect more heat instead of absorbing it. Thus, the lighter the
colour of the concrete involved in the construction of the building, the less the effect of
the urban heat environment will be. Blast furnace cement therefore serves to contribute
to the mitigation of this effect, contributing towards a positive environmental impact.
The following organisations have found evidence in support of the use of GBFS as an
environmentally friendly product:
1. The Cement and Concrete Institute (CnCi) have on numerous occasions promoted
the use of GBFS as a green extender for cement production (CnCi, 2013). The use
of GBFS reduces the pressure on South African resources as it eliminates some of
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
the need to produce new extenders by utilizing an existing product. GBFS also
significantly reduces the energy consumption and greenhouse gasses emitted in
the production of alternative raw materials. Above mentioned benefits results in
huge reductions in carbon emissions and a more sustainable approach to meeting
the demand for cement in a growing economy. As such, slag cement is helping to
fulfil almost every criterion stated in the objectives of the National Environmental
Management: Waste Act of 2008. To consider GBFS a waste product would clearly
be counterproductive to achieving the goals of the act.
2. The US National Slag Association wanted to prove that GBFS is suitable for use in
industrial and construction applications. Through collaboration with governmental
agencies, environmental toxicologists and scientists it was approved for use by
various Environmental Regulatory Agencies. The findings on the environmental
impact are further discussed below.
The production process of GBFS eliminates the presence of organic, semi-volatile
or volatile compounds in the product (NSA, 2013). GBFS contains the same
compounds as found the natural environment, and the metals in GBFS are fused
together and tightly bound. This means that the metals are not easily leached into
the environment as they are not readily liberated from the slag particle (Green &
Wintenborn, 1998).
3. In support of slag as an environmentally friendly product The US National Slag
Institute issued the following statement:
“Using Iron Furnace Slag will help preserve our natural resources. Based on the
numerous environmental tests, studies and reviews by governmental agencies and
the iron and steel industry we know that iron and steel slag is a safe and valuable
resource, and we encourage its use as an environmentally friendly product.”
4. The Army Corps of Engineers in the United States of America conducted an
Environmental Impact Study which investigated the occurrence of leaching from
GBFS as well as the long term environmental impact it would have. The study
found that leaching from GBFS is extremely uncommon and that the long-term
impact of leaching on the environment is minimal, and that little, if any,
environmental damage is to be expected to an eco-system due to the presence of
GBFS in an aquatic environment (NSA, 2013).
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
5. Another organisation which undertook an assessment of the risks associated with
utilisation of slag from the iron and steel making process was the Steel Slag
Coalition (SSC). The SSC is a group of 63 companies that produce steel, slag or
both. Three risk assessments where conducted on behalf of the Steel Slag Coalition
to investigate the potential human health and ecological risks associated with
exposure to slag (NSA, 2013). The following where key findings:
• “Carcinogenic and non carcinogenic risks associated with steelmaking slag are
insignificant for potentially exposed residential populations, farmers, or
maintenance, industrial and construction workers.
• Metals in steelmaking slag will not leach readily in substantial amounts to
groundwater or, surface water and, therefore, pose little or no concern for
drinking water quality.
• Steelmaking slag will not significantly impact animals and other terrestrial life
in or near areas of application. Metals in steelmaking slag do not bio
accumulate in the food web and are not expected to bio concentrate in plant
tissue.
• Steelmaking slag may be applied safely in aquatic environments such as rivers,
lakes and streams without impacting water quality or aquatic life (NSA, 2013).”
6. The Human Health and Ecological Risk Assessment (HERA) was conducted by
environmental scientists and toxicologists from various industries. It found the
following:
• Even in case of worst case exposure, the use of BFS in a variety of industrial
and construction applications, poses no meaningful threat to human health or
the health of the surrounding environment.
• The metals contained in the GBFS are not readily available for uptake by plants,
animals or humans and do also not bio accumulate in the food web, nor do
they bio concentrate in plant tissue (NSA, 2013).
In conclusion, taking into consideration the findings of all of the above assessments and
studies it can be concluded that the use of GBFS is not only environmentally safe, it also
benefits the environment and poses no significant risk to human or environmental
health.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
2. South African Legislation
a. NEMWA
South African Environmental Law is governed by The Constitution as well as The National
Environmental Management Act No 107, 1998 (NEMA) and the associated supporting
pieces of legislation. The National Environmental Management: Waste Act No. 59, 2008
(NEM: WA) is the relevant piece of legislation that, under guidance of the NEMA, governs
the matter of waste in the South Africa.
b. Definitions
Chapter 1 of the NEM: WA act sets out the relevant definitions of the principle terms, the
relevant definitions are listed below:
“by-product” means a substance that is produced as part of a process that is primarily
intended to produce another substance or product and that has the characteristics of an
equivalent virgin product or material
“waste” means any substance, whether or not that substance can be reduced, re-used,
recycled and recovered –
(b) That is surplus, unwanted, rejected, discarded, abandoned or disposed of
(c) Which the generator has no further use of for the purposes of production
(d) That must be treated or disposed of; or
(e) That is identified as a waste by the Minister by notice in the Gazette
And includes waste generated by the mining, medical or other sector, but –
(i) A by-product is not considered waste; and
(ii) Any portion of waste, once re-used, recycled, recycled and recovered ceases to be a
waste”
“recovery” means the controlled extraction of a material or the retrieval of energy from
waste to produce a product
“recycle” means a process where waste is reclaimed for further use, which process involves
the separation of waste from a waste stream and the processing of that separated material
as a product or raw material
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
“re-use” means to utilize articles from the waste stream again for a similar or different
purpose without changing the form or properties of the articles
“hazardous waste” means any waste that contains organic or inorganic elements or
compounds that may, owing to the inherent physical, chemical or toxicological
characteristics of that waste, have a detrimental impact on health and the environment.
c. Objectives of NEMWA
The National Environmental Management: Waste Act of 2008 states in section 1.2 (a) the
objectives of the act, these are listed below.
“2. The objectives of this act are-
(a)to protect health, well-being and the environment by providing reasonable measures
for—
(i) minimising the consumption of natural resources;
(ii) avoiding and minimising the generation of waste;
(iii) reducing, re-using, recycling and recovering waste;
(iv) treating and safely disposing of waste as a last resort;
(vi) preventing pollution and ecological degradation;
(vii) securing ecologically sustainable development while promoting justifiable economic
and social development;
(vii) promoting and ensuring the effective delivery of waste services;
remediating land where contamination presents, or may present, a significant risk of harm
to health or the environment; and
(ix) achieving integrated waste management reporting and planning;
(b) to ensure that people are aware of the impact of waste on their health, wellbeing and
the environment;
(c) to provide for compliance with the measures set out in paragraph (a) and
generally, to give effect to section 24 of the Constitution in order to secure an environment
that is not harmful to health and well-being.
The use of Granulated Blast Furnace Slag meets the objectives of the act in that it;
• Minimises the consumption of natural resources used in the production of cement
by 4.3 – 14.6% (Prudinski et al, 2002)
• It avoids and minimises the generation of waste. Seeing as the producer of GBFS
takes it unto themselves to produce a product that complies with all the relevant
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
regulations and requirements, it minimises the amount of BFS that could possibly
not have been used in the cement production process.
• The use of GBFS encourages the recovery of BFS through various processes
including the rapid cooling and granulation of the BFS to produce GBFS, a product
that is utilised by cement producers and other consumers. Due to the recovering of
the BFS, GBFS is not a waste, but a product
• Prevents the pollution and degradation of the environment. Slag cement, as found
by Prudinski et al, results in energy savings of 21.1 – 48.4% as well as reducing the
Co2 emissions resulting from the production of cement by between 29.2 – 46.1%.
• Encompasses ecologically sustainable development through the use of a greener,
more environmentally friendly, building material that has less of an impact on the
environment.
• The use of GBFS also promotes justifiable economic and social development in that
consumers of cement have the option of utilising a product that has been
responsibly produced. Synergies could also further develop between steel, slag,
cement and concrete manufacturers that would stimulate the local economy.
d. Interpretation
It is the opinion of Osho SA Cement that slag cannot be considered to be a waste product
under the National Environmental Management: Waste Act of 2008. Several clauses in the
definition of the act preclude the classification of GBFS as a waste:
Waste means “Any substance, whether or not that substance can be reduced, re-used,
recycled and recovered”
(a) that is surplus, unwanted, rejected, discarded, abandoned or disposed of;
GBFS cannot be classified as any of the above. As discussed in previous sections GBFS is
a product that is produced based on market demand and requirements. It is a
domestically and internationally traded commodity with many uses and a high
monetary value. Superior quality GBFS will not be disposed of- it will be sold. The
demand for GBFS in Japan is so high that unless the iron and steel producers increase
production, there is no additional GBFS available. All GBFS currently being produced in
Japan has already been sold. On the South African market it is becoming increasingly
difficult to obtain GBFS as most producers have long term contracts for the uptake of all
produced GBFS.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
(b) which the generator has no further use of for the purposes of production;
At a certain phase of the iron and steel production process, the re-introduction of
phosphorus into the steel is particularly dangerous. After further research by the steel
industry it was found that BFS can be processed and applied to remove impurities
(phosphorus) from the production stream. Slag is used to counter the re-introduction of
the phosphorus into the process by extracting the metal globules from slag, by the use
of metallic extraction techniques, and adding the globules to the blast furnace feed
(Ochola, 2009).
Molten slag is also subject to various cooling techniques to form GBFS, and most steel
producers worldwide have invested in Granulation Plants in order to continue with the
integrated production process of GBFS. If the generator had no further use for slag there
would be no need to subject it to this process, or to invest so greatly in technology to
further process the product.
The assumption that the producer will not have further use of slag would be assuming
that the producer will also not have further use of the product produced in parallel to
BFS, steel. Therefore it is clear that the producer does in fact have additional uses for
the product.
(c) that must be treated or disposed of
Slag need not be treated. It is processed in order to create a higher value product in the
form of GBFS, but it can be sold unprocessed as air or water cooled slag for industries
such as concrete making. There is also no requirement that GBFS must be disposed of, it
is a valuable product that in high demand on the international as well as local market
and therefore will be sold to consumers that require a high quality material for their
production processes.
(d) that is identified as a waste by the Minister by notice in the Gazette, and includes
waste generated by the mining, medical or other sector, but
(i) a by-product is not considered waste
GBFS can, at the lowest estimation be considered a by-product, although to call it a co
product is more accurate. Currently no definition exists in the South African waste
legislation for a co-product. GBFS and iron are two distinct products that are created
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
in the process of smelting, each with their own properties, uses, and values. Similarly
to Iron being further processed for various uses, BFS is further processed to form GBFS
to be used in the Cement manufacturing process.
(ii) any portion of waste, once re-used, recycled and recovered, ceases to be waste
Even if Blast Furnace Slag were considered to be a waste product, the processes
undertaken by producers to produce GBFS would preclude it from remaining a waste.
After the creation of Blast Furnace Slag in the furnace, it is water-cooled, crushed and
ground to create GBFS. This process adds a new usage to the slag (that of cement
making) and is sufficient evidence that it has been recovered, and therefore ceases to
be a waste.
e. GBFS as a non-hazardous material
The South African legal definition of hazardous waste is currently undergoing revision as it is
believed to be too stringent in some of its classifications.
However the South African Department of Water Affairs and Forestry’s document
“Minimum Requirements for the Handling, Classification and Disposal of Hazardous Waste”
of 1998 can be referred to for an indication of the current classification criteria.
According to this document, a hazardous waste is defined as follows:
"an inorganic or organic element or compound that, because of its toxicological, physical,
chemical or persistency properties may exercise detrimental acute or chronic impacts on
human health and the environment. It can be generated from a wide range of commercial,
industrial, agricultural and domestic activities and may take the form of liquid, sludge or
solid. These characteristics contribute not only to degree of hazard, but are also of great
importance in the ultimate choice of a safe and environmentally acceptable method of
disposal."
Further to this, a Hazardous Waste can be defined as a waste that directly or indirectly
represents a threat to human health or the environment by introducing one or more of the
following risks:
• Explosion or fire;
• Infections, pathogens, parasites or their vectors;
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
• Chemical instability, reactions or corrosion;
• Acute or chronic toxicity;
• Cancer, mutations or birth defects;
• Toxicity or damage to the ecosystems or natural resources;
• Accumulation in biological food chains, persistence in the environment, or multiple effects
to the extent that it requires special attention and cannot be released into the environment
or be added to sewage or be stored in a situation which is either open to air or from which
aqueous leachate could emanate.
Under such definition, GBFS cannot be considered to be hazardous. GBFS is not explosive or
flammable, nor does it contain any live organic materials so it would not be likely to cause
any infections, pathogens or parasites. GBFS is also a stable substance that possesses a
neutral PH level; it is not acutely or chronically toxic. No cancer, mutations or birth defects
have been reported or even realistically considered to be associated to GBFS. With regards
to the toxicity, or damage to an ecosystem or natural resource; GBFS poses no danger if it is
utilised as a product. Numerous studies have been conducted, as discussed in previous
chapters, on the impact on human health and concluded that GBFS is not regarded as toxic
to humans.
GBFS, due to its glassy nature will not release leachate. As such it is safe to store or dispose
of. A 2000 study by Proctor et al entitled “Physical and Chemical Characteristics of Blast
Furnace, Basic Oxygen Furnace, and Electric Arc Furnace Steel Slags” studied the degrees of
to which leachate is released by the various types of slag produced by the steel industry. It
concluded that GBFS does not exceed TCLP leaching thresholds. While GBFS may have some
metal content higher than those occurring in natural soil, metals in the GBFS are not
released due to tightly bound compounds in the GBFS. In addition, the large particle sizes of
GBFS relative to those of soil reduce the possibility for inhalation, and as such reduce the
possibility for human exposure. The report concluded GBFS to be a safe material (NSA,
2013).
As such, GBFS cannot be classified as a hazardous waste under the conditions South African
Department of Water Affairs and Forestry’s “Minimum Requirements for the Handling,
Classification and Disposal of Hazardous Waste” of 1998. It is a safe material that poses no
significant risks to human health.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
3. International Standing
Historically slag has long been regarded as a waste, this can be contributed to various factors
including; poor past usage of slag, inadequate quality, lack of further processing in order to be
further utilised in other manufacturing processes as well as a lack of understanding of the
applications of a product such as BFS. In the 19th century, it was fair to consider slag as waste as
there was little being used and there were few known usages. Blast Furnace Slag was being
produced at a much lower quality (it was only air-cooled and full of impurities), and as such
could not be used in products like cement. However, as further research has been conducted
and its usage and usefulness has improved, it has become increasingly looked on favourably as
a product, by-product or co-product by various individuals, organizations and countries.
a. The Basel Convention on the Control of Transboundary Movements
of Hazardous Wastes and their Disposal of 1989
The Basel Convention regulates movement of Hazardous Wastes and Wastes. The
convention was first signed in 1992 and in May 1994 South Africa became a signatory. The
Basel Convention contains an in depth classification system for wastes and hazardous
wastes. This classification is relied upon by various nations to steer local classification
systems in order to comply with and form part of the Basel Convention.
The Basel Convention states; “that the transboundary movements of hazardous wastes and
other wastes should be permitted only when the transport and the ultimate disposal of such
waste is environmentally sound”.
The Basel Convention defines the scope of the convention in Article 1:
“1. The following wastes that are subject to transboundary movement shall be “hazardous
wastes” for the purposes of this Convention:
(a) Wastes that belong to any category contained in Annex I, unless they do not
possess any of the characteristics contained in Annex III; and
(b) Wastes that are not covered under paragraph (a) but are defined as, or
considered to be, hazardous wastes by the domestic legislation of the Party
of export, import or transit.”
Under the Basel Convention, Annex I, Granulated Slag arising from the manufacture of Iron
and Steel is not classified as a hazardous waste; it does also not possess any of the
characteristics contained in Annex III.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
The National Waste Management Strategy is currently being realigned to reflect the
classifications of the Basel Convention, therefore it can be assumed that if GBFS is not
classified a hazardous waste under the Basel Convention, by association it will not be
classified as a hazardous waste under NEMWA.
b. Europe
In a position paper on the status of Ferrous Slag published by the European Slag Association
and the European Steel Association in April 2012, it states that in 2010 Europe saw the
production of 23.5 million tonnes of blast furnace slag, about 82% of this slag was
granulated. The rate of utilization of slag was somewhat higher than production and slag
from deposits was also used. 66% of the GBFS was used as a component for the cement
production or as concrete addition. Other uses such as aggregate in road construction
account for 23%.
Most European countries have an utilisation rate of 100%, with only one year, 2010, been
recorded where the utilization rate in Europe fell to about 90%.
• The European Waste Framework Directive defines waste as: “any substance or
object that the holder discards or intends to discard or is required to discard”
i. For the intention to discard: The producer does not intend to discard the
slag because he performs a variety of measures to fulfil the requirements
and sell the slag to a customer as a product to be used
ii. Requirement to discard: No regulations that require slag to be discarded
exist.
• In Europe the Waste Framework Directive allows for a clear definition of criteria
characterising a by-product, as well as a substance or material which shall cease to
be regarded as a waste and finally becomes a useful product or secondary raw
material.
i. By Product:
• 1. A substance or object, resulting from a production process, the
primary aim of which is not the production of that item, may be
regarded as not being waste but as being a by-product only if the
following conditions are met:
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
i. A. Further use of the substance or object is certain;
ii. B. Further use of the substance or object can be used directly
without any further processing other than normal industrial
practice;
Today 90-100% of the blast furnace slag in Europe is used mainly for the production of cement or as an addition for concrete. There are also numerous national standards and specifications that exist in terms of slag quality and composition. Therefore the first criteria fulfilled.
In order to regulate the quality of slag produced different measures are applied during the generation of slag. These measures include:
1. Treatments in the molten state (e.g. addition of stabilisation
substances) to influence the properties of slag and adhere
to requirements of standards and specifications.
2. Specific treatment processes like rapid cooling
3. Separation of iron content through magnetic processes
4. Weathering to achieve volume stability.
Therefore it can be stated that slag has a controlled chemistry and that treatments are done as part of normal industrial practice, in order to improve the slag quality with the objective of fulfilling a specific function. Therefore GBFS complies with the second criterion.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
iii. C. The substance or object is produced as an integral part of a
production process; and
iv. D. Further use is lawful
• 2. “End of Waste Status” defines conditions for materials that fall outside the
definition of by-products but have the potential to cease to be a waste.
• Such materials or substances are initially regarded as waste but may leave the
waste regime and become a product/secondary raw material by fulfilling certain
criteria:
o “Certain specified waste shall cease to be waste when it has undergone a
recovery, including recycling, operation and complies with specific
criteria to be developed in accordance with the following:
� A. The substance or object is commonly used for specific
purposes;
Slag formation is part of the intrinsic process of steel production as it facilitates the reactions needed for the production of steel. GBFS is generated simultaneously with the production of liquid iron. Thus slag generation is definitely an integral part of the iron/steel production processes.
Slag meets the requirements of national and European technical standards in relation to its intended use. Environmental and health standards are also met.
Today 90-100% of the blast furnace slag in Europe is used mainly for the production of cement or as an addition for concrete. There are also numerous national standards and specifications that exist in terms of slag quality and composition. Therefore the first criteria are fulfilled.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
� B. A market or demand exists for such a substance or object;
� C. The substance or object fulfils the technical requirements for
the specific purpose and meets the existing legislation and
standards applicable to products; and
� D. The use of the substance or object will not lead to overall
adverse environmental or human health impacts
Most European countries have a utilization rate of 100%, with only one year, 2010, been recorded where the utilization rate in Europe fell to about 90%. Produced steel slag is used on qualified fields of application and thus is brought onto the market. Subsequently, it can be stated that a market definitely exists for GBFS. Most of the producers service the market continuously within commercial contracts. Also the fact that standards and specifications exists is proof of a market.
GBFS meets the requirements of national and European technical standards in relation to its intended use. Environmental and health standards are also met.
GBFS, that is not discarded but used for a specific application, meets all requirements of national standards concerning environmental aspects. Research conducted by REACH support the conclusion the use of GBFS will not lead to overall adverse environmental or human health impacts.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
Therefore it can be stated that GBFS meets all end of waste criteria leading to a product or
secondary raw material classification.
This exert below is communication from the Commission to the Council and the European
Parliament on the Interpretative Communication on waste and by-products. The commission
highlights various factors that contribute to the classification of BFS outside of waste. Table one
illustrates the classification of GBFS in various European countries (UK Environmental Agency,
2013).
“Blast furnace slag is produced in parallel with hot iron in a blast furnace. The production
process of the iron is adapted to ensure that the slag has the requisite technical qualities. A
technical choice is made at the start of the production process that determines the type of slag
that is produced. Moreover, use of the slag is certain in a number of clearly defined end uses,
and demand is high. Blast furnace slag can be used directly at the end of the production process,
without further processing that is not an integral part of this production process (such as
crushing to get the appropriate particle size). The material can therefore be considered to fall
outside of the definition of waste.”
Table 1: Present status of GBFS in European countries
Country Year Classification
Austria 1991 Non waste
Austria 1999 Product
Germany 2006/2007 Non Waste
Belgium 2007 By-product (as
basic
component for
cement
production)
EU 2007 By product
UK 2007 By product
Finland 2008 Product
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
d. International Legal Precedent
In 2008, during the Palin Granit case, the Supreme Court in Finland brought forward two
criteria to determine if a substance is a waste.
1. The material should not be a production residue but a by-product. The court further clarifies
that; “Goods, material or raw material resulting from a manufacturing or extraction process,
the primary aim of which the undertaking does not wish to discard but intends to exploit or
market on terms which are advantageous to it, in a subsequent process, without any further
processing prior to reuse.”
• Steel and GBFS manufacturers do not intend to discard the GBFS, the intention is to
produce a product that conforms to the requirements and then sell the product to a
consumer that would be able to utilise it as part of their process. Therefore steel
manufacturers introduce various techniques in the blast furnace in order to produce a
high quality blast furnace slag that will be fed into the granulation plant for the final
production step. The GBFS can then be used, as is, in the cement manufacturing process.
2. The material must have a certain reuse with a strong degree of likelihood and must no
longer be regarded as a burden which its holder seeks to discard; “in addition to the criterion
of whether a substance constitutes a production residue, a second relevant criterion for
determining whether or not a substance is a waste is the degree of likelihood that that
substance will be reused, without any further processing prior to its reuse. If there is also a
financial advantage to the holder in so doing, the likelihood of reuse is high. In such
circumstances the substance in question must no longer be regarded as a burden which its
holder seeks to discard, but as a genuine product.”
• The likelihood of use of GBFS is extremely high, as mentioned in previous sections.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
5. South African Cement Industry Opinion
The viewpoint of the major domestic cement producers is unanimous- all regard slag to be a by
product and have stated as such.
PPC: As noted in the Public Participation document published by Aurecon on behalf of PPC on the
15th of February 2011, Slag is stated to be a product.
AfriSam: AfriSam’s website defines GBFS as a “by-product of the steel and iron industry”
http://www.afrisam.co.za/products-services/slagment/
NPC: NPC’s website defines GBFS as “the non metallic mineral by-product that arises from the
reduction of iron ore to metallic iron in a furnace”.
http://www.npc.co.za/pages/20927_products
Lafarge: Lafarge’s website states that GBFS is “a by-product of the steel industry”
http://www.lafarge.ae/wps/portal/ae/2_2-
Detail?WCM_GLOBAL_CONTEXT=/wps/wcm/connectlib_ae/Site_ae/AllProductDataSheet/GGB
S/Product_EN
6. Conclusion
It is the opinion of Osho Cement (Pty) limited that, after studying Granulated Blast Furnace Slag
and the production process, it is a product. BFS is produced in parallel to iron and the
integrated production process is then continued through the cooling, crushing and granulation
of BFS to produce Granulated Blast Furnace Slag. GBFS can be used as is in the Slag Cement
Manufacturing Process, and has various other applications as discussed in the paper, and is in
high demand where in many countries the product is completely sold out. The GBFS needs to
comply with various international and national standards, regulations and legislation for
example SANS50197.
The environmental, economical and social benefits associated with the use of GBFS are
immense and should not be disregarded. GBFS is a product with great value and a number of
applications. Classifying GBFS as a waste is not in support of the objectives of the NEM: WA,
and would be counterproductive to reaching the objectives set out in the aforementioned act.
Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
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development
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Disposal, 5 May 1992.
Britpave, 2004: Britpave Technical Data Sheet: Stabilised soils as subbase or base for roads and
other pavements, http://www.britpave.org.uk
Cement and Concrete Institute, In Perspective,
http://www.cnci.org.za/en/Content/Pages/Sustainability/In-Perspective, 12 April 2013
Cramer et al, 2007: Effects of Ground Granulated Blast Furnace Slag in Portland Cement
Concrete (PCC) – Expanded Study, University of Wisconsin, Department of Civil and
Environmental Engineering.
DWAF, 1998: Minimum Requirements for Handling, Classification and Disposal of Hazardous
Waste.
EuroSlag, 2006: Legal Status of Slags Position Paper,
http://www.euroslag.com/fileadmin/_media/images/Status_of_slag/Position_paper_Jan_2006
EuroSlag & EuroFer, 2012: Position Paper on the status of Ferrous Slag,
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2.pdf
Green, J.J & Wintenborn, J.L. 1998: Steelmaking Slag: a safe and valuable product,
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Directors: V.K.Agrawal, Tushar Agrawal, Sumit Agrawal
Company Registration Number: 2007/032830/07
National Slag Association: Leachate from Blast Furnace Slag, http://www.nationalslag.org,26
March 2013
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2013
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Nippon Slag Association, Iron and Steel Slag Products and Production Process,
http://www.slg.jp/e/slag/process.html, 12 April 2013
Ochola, C. 2009: Utilizing Iron and Steel Slags in Environmental Applications – An overview,
http://www.nationalslag.org/archive/slag_paper_d2.pdf
Prusinski et al, 2006: Life Cycle Inventory of Slag Cement Concrete, Eight CANMET/ACI:
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