position paper on the status of granulated blast furnace ...projects.gibb.co.za/portals/3/osho...

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

[email protected]



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



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.



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.



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.



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.



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.



• 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



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



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.



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).



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



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



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



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).



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.



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



“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



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.



(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



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;



• 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.



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.



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:



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.



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.



� 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.



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



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.



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.



Consulted Resources

Aynsley, D. 2005: Material Classification of Iron and Steel Slag By-product Investigation,

Australasian (Iron and Steel) Slag Association Inc. http://www.asa-inc.org.au/research-and-

development

Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their

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

.pdf

EuroSlag & EuroFer, 2012: Position Paper on the status of Ferrous Slag,

http://www.euroslag.com/fileadmin/_media/images/Status_of_slag/Position_Paper_April_201

2.pdf

Green, J.J & Wintenborn, J.L. 1998: Steelmaking Slag: a safe and valuable product,

http://nationalslag.org

Lewis, D. 1980: Iron and Steel Slag – A non Hazard, http://www.nationalslag.org

National Slag Association, Blast Furnace Slag, http://www.nationalslag.org/blastfurnace.htm ,

11 April 2013.



National Slag Association: Leachate from Blast Furnace Slag, http://www.nationalslag.org,26

March 2013

National Slag Association: Slag a Green Product in its own right, http://www.nationalslag.org,26

March 2013

National Slag Association – Environmental Committee: Iron and Steel making slag –

Environmentally Responsible Construction Aggregates, http://www.nationalslag.org,26 March

2013

National Environmental Management: Waste Act, Act No. 59 of 2008

National Environmental Management: Waste Act: Waste Classification and Management

Regulations, 10 August 2012

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:

International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete

SCA, 2013: Reducing Portland cement in concrete,

http://slagcement.org/sustainability/reducing.html

Slag Cement Association, 2002: Slag Cement and Fly Ash, http://www.slagment.org

Smithers, P. 2010: Global Ferrous Slag Market poised to reach almost $28 billion by 2020,

https://www.smitherspira.com/global-ferrous-slag-market-poised-to-reach-almost-usd28-

billion-by-2020.aspx, 12 April 2013

The American Iron and Steel Association, The Environmentally Preferred Material,

http://www.steel.org/~/media/Files/AISI/Fact%20Sheets/environmentbrochure.pdf , 12 April

2013.

UK Environmental Agency: Regulatory position statement: Blas Furnace Slag as a by-product,

http://www.environment-agency.gov.uk 27 March 2013



Yadu et al, 2013: Stabilization of soft soil with granulated blast furnace slag and fly ash,

http://www.ijret.org/

position paper on the status of granulated blast furnace ...projects.gibb.co.za/portals/3/osho...

Documents