A TERM PAPER ON THE LIFE CYCLE ASSESSMENT

A TERM PAPER ON THE
LIFE CYCLE ASSESSMENT (LCA) OF THE CEMENT
INDUSTRY

BY
CHUKWUNENYE, Precious Oganihu
CHE/11/6514

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TO BE SUBMITTED TO
DR. OLUWASINA & DR OGUNJOBI
CHEMISTRY DEPARTMENT,
FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE

APRIL, 2018

LIFE CYCLE ASSESSMENT OF THE CEMENT INDUSTRY

TABLE OF CONTENT
Title page
Table of content
List of figures
Abstract
1.0 INTRODUCTION
1.1 Definition of terms
1.2 Life cycle Assessment
1.3 Cement
1.4 Sustainability
2.0 CEMENT
2.1 Types of Cement
2.2 Raw materials and additives for cement production
2.3 Production of cement
2.3.1 Quarrying
2.3.2 Mixing of raw material
2.3.3 Burning/Clinkering
2.3.4 Grinding
3.0 WASTE
3.1 Sources/types of waste generated
3.1.1 Airborne pollutions
3.1.2 Solid waste
3.2 Waste management practices

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3.2.1 Wastewater treatment
3.2.2 Solid waste treatment
4.0 CONCLUSION
REFERENCES

LIFE CYCLE ASSESSMENT OF THE CEMENT INDUSTRY

LIST OF FIGURES
Figure 1 Cradle to grave ……………………………………………………………………………………………… 7
Figure 2 Simplified flowchart of cement manufacture …………………………………………………….. 9
Figure 3 Flow diagram of dry and wet process of cement manufacture ……………………………. 10

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ABSTRACT
An obvious evidence of increasing population and development is the construction of various
buildings and structures. In Nigeria, recent years have seen an increase in the erection of
diverse buildings (O.O. Akinkurolere, 2013). This increase in construction has led to an
increase in the demand of construction materials, of importance is cement.
This term paper is written with the aim of reviewing the cement industry while giving
particular attention to the sustainable industrial waste practices being used currently.

Keywords: sustainability, cement, waste, wastewater treatment, waste treatment, cement
production, waste treatment, energy recovery

LIFE CYCLE ASSESSMENT OF THE CEMENT INDUSTRY

CHAPTER ONE
1.0 INTRODUCTION
Cement, according to Wictionary, can be defined as a bond of union; that which unites firmly
or any material with strong adhesive properties. However, in this context, an alternate
definition is implied. Cement is defined as the fine grey powder which binds sand and gravel
into a hard substance (concrete) when mixed with water (Michael A. Nisbet, 2002).
This paper seeks to evaluate the production of cement, the sources and types of waste
generated and the sustainability of the waste management practices employed in terms of
cost, continuity and environmental impact.
1.1 Definition of terms
To avoid any sort of ambiguity, major terms and words used in this term paper are explicitly
defined in the context in which they are used.
1.2 Life Cycle Assessment (LCA)
Life Cycle Assessment can be defined, in simple terms as, a general method for evaluating
the inputs and outputs of energy and materials and the environmental impacts that are as a
result of a product or service during the course of its life cycle (Michael A. Nisbet, 2002).
It was developed at a time when the diminishing fossil fuel became a real concern for
researchers and they sought out ways to understand the effects of energy use.
Life cycle Assessment, also called life cycle Analysis, is used to examine the environmental
effect of a product from cradle to grave, i.e. throughout its lifetime.

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Figure 1 Cradle to grave
1.3 Cement
A common error is to assume that concrete means the same as cement as they are usually
interchangeable. However, cement is just a constituent of concrete which usually also
contains sand and gravel.
1.4 Sustainability
It is generally defined as the development of processes which can be maintained in terms of
ecological balance that is, using the available resources while maintaining the balance of that
area. In terms of waste management, it is the utilization of waste produced with the aim of
reducing material resources (Priyanka Pathak, n.d.)

LIFE CYCLE ASSESSMENT OF THE CEMENT INDUSTRY

CHAPTER TWO
2.0 CEMENT
Cement has already been established as a powder that when mixed with water, hardens to
become concrete. The major compositions of cement are lime, silica, alumina, etc. (for
Portland cement).
2.1 Types of cement
There are various types of cements depending on their intended use. Some of them are listed
below:
? Low heat cement
? Rapid hardening cement
? White cement
? Portland cement
? High alumina cement
2.2 Raw materials for cement production
The following are used for Portland cement production:
? Lime (CaO)
? Alumina (Al2O3)
? Silica (SiO2)
? Iron (Fe2O3)
? Gypsum (CaSO4 . 2H2O)

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The pre-treatment given to the raw materials depends on the intended process. If the wet
process is to be used, the chalk (if used) is grounded and dispersed with water in a wash mill.
The limestone is also crushed before being sent to the ball mill (Patel, n.d.).
2.3 Production of cement
The production of cement involves these major steps:
? Quarrying
? Mixing of the raw materials
? Burning/Clinkering
? Grinding
? Packaging and storage

Figure 2 Simplified flowchart of cement manufacture

LIFE CYCLE ASSESSMENT OF THE CEMENT INDUSTRY

2.3.1 Quarrying
This involves mining of the raw materials like limestone and cement rock. These two provide
the lime, silica, iron, and alumina.
2.3.2 Mixing of the raw material
This stage brings together the calcareous (CaCO3) materials and the argillaceous materials
(clay particles). Two processes could be used during this stage: dry or wet process. The dry
process involves mixing the raw materials in the dry, powder form in the required proportions
before sending the mixture to the kiln for burning. A simplified flowchart of the dry process
could be seen in Figure 2 below.

Figure 3 Flow diagram of dry and wet process of cement manufacture

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The wet process, on the other hand, water is added to the clay to wash away organic matter as
shown in the Figure 2 below. The wet clay and the grinded limestone are mixed to form
slurry. The slurry usually has a 38-40% water percentage after mixing.
2.3.3 Burning/Clinkering
This involves heating the raw material at a very high temperature as high as 17500C. This
occurs in a rotating kiln. This step of the production requires a lot of energy. It is at this stage
the clinker is formed consisting of tricalcium silicate, dicalcium silicate, tricalcium aluminate
and tetracalcium aluminoferrate.
2.3.4 Grinding
Since the clinker is in solid form and is of very little usefulness in this form, it is grinded to
powder which is packaged and sold as cement in portable bags.

LIFE CYCLE ASSESSMENT OF THE CEMENT INDUSTRY

CHAPTER THREE
3.0 WASTE
Waste now has several meanings which depends on who is defining. For example, the sludge
in the drinks industry might be classified as waste whereas; the fertilizer industry would
consider it as raw material. The increasing population and shift towards a greener world has
necessitated the development of eco-friendly ways of managing waste. One way this is
achieved is making landfill the last resort in waste management (Cement Sustainability
Initiative, 2014). The cement industry is considered as one of the biggest generators of
pollution in Nigeria among slaughterhouses, fertilizer industry among others (Olajumoke F.
Kayode, 2018).
In previous years, the waste produced by the activities in the production of cement met with
disposals in landfills or a similar fate. However, thanks to the global Green Movement, about
35 years ago, cement industry waste was no longer considered waste but raw material and
energy. Today, in many countries, the cement industry practices very good waste
management because a good amount of the waste produced is used as substitute fuel for the
kilns. This lowers the dependence of the industry on fossil fuel combustion and its impact on
the environment (Cement Sustainability Initiative, 2014). In the cement industry, different
types of waste are produced from several unit operations carried out in the production and
usage.
This chapter seeks to review the types and sources of waste; management and the developing
ways of using waste for energy generation.

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3.1 Sources/types of waste generated
At various stages of the production of cement, different waste could be emitted. During the
crushing of the raw materials, there is the release of airborne emissions. These emissions
usually contain particulate matter which has several environmental effects. Also, during the
blending, water effluents are released and solid waste would be produced during the cooling,
storage and grinding of the clinker. There are other environmental interactions that occur
during the packing, dispatch, use and disposal of cement products.
3.1.1 Airborne pollutions
Several gases are released during the production of cement, of major concern being, carbon
dioxide. During burning, combustion of several organic materials occurs. This happens
because the materials used to supply the heat needed could be waste from other sources, like
used tyres. As the world seeks to protect her environment, many ways to handle the emission
of CO2 is being developed. Examples of such ways are carbon capture and storage, use of
supercritical CO2 for the treatment of lime/concrete, biodiesel production from algae and
electrochemical carbon reduction (Potgieter, 2012).
Other airborne pollutions are SOx and NOx compounds which are also classified as
greenhouse gases because of their effects. They are known to cause acid rain and smog. Ways
by which they are managed include modification of the burner design, reduction of the
temperature used for firing, adsorption of the sulphur compounds in a limestone slurry, etc.
Particulate dust is also classified as air pollution and the cement industry is considered to be
the largest contributor of this pollution. It was reported that the amount of particulate dust
was about 56100g/m3 around a particular cement plant (Asubiojo, 2016). In Nigeria, research

LIFE CYCLE ASSESSMENT OF THE CEMENT INDUSTRY

has shown that this is causing respiratory diseases and other diseases for workers in factories
producing cements.
3.1.2 Solid waste
This refers to wastes usually in solid form which can be secondary products of a certain
process. Under consideration is the industrial solid waste generated in the lifecycle of cement.
Solid waste has been identified as one of the most pressing issues facing developing countries
(Napoleon S. Momodu, 2011).
3.2 Waste management practices
3.2.1 Wastewater treatment
Water is usually used for various processes in cement production. The effluent from the plant
is usually treated before being discharged into water bodies. Sadly, despite the treatment, the
effluent released might still affect the quality of the body it is discharged to. This was the
case of the Onyi river in Kogi state caused by Obajana cement factory (Ipeaiyeda & Obaje,
2017).
3.2.2 Solid waste treatment
A method which is has been developed to aid sustainability in cement production is the use of
municipal solid waste as a raw material during its production (Kikuchi, 2001). It has also
become a common technology in many countries to utilize the wastes from communal and
industrial sources as an alternative fuel for the cement kilns (Nickolaos Chatziaras, 2016).

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CONCLUSION
Thanks to continuous research, the environmental impact of the cement industry is being
reduced as new technologies and methods are being developed. However, a lot is still left to
be desired as cleaner ways and greener methods can be developed which would solve many
of the problems currently associated with the cement industry.
Some alternative ways that have been suggested include the inclusion of preheaters and
precalciner to increase the energy efficiency of the production process (Potgieter, 2012).
Also, more waste from other sources should be used as raw material for the generation of
heat in the kilns (Cement Sustainability Initiative, 2014).
The cement industry could still go further to develop ways that would be both sustainable in
terms of cost and continuity but would also reduce the environmental impact of several
practices currently employed.

LIFE CYCLE ASSESSMENT OF THE CEMENT INDUSTRY

REFERENCES
Asubiojo, O.I., 2016. Pollution sources in the Nigerian environment and their health implications. Ife
Journal of Science, 18(4), pp.973-80.
Cement Sustainability Initiative, 2014. 978-2-940521-18-0 The Cement Industry: Creating solutions
for safe, resource-efficient waste management. WBCSD.
Ipeaiyeda, A.R. & Obaje, G.M., 2017. Impact of cement effluent on water quality of rivers: A case
study of Onyi river at Obajana, Nigeria. Cogent Environmental Science, 3, pp.1-15.
Kikuchi, R., 2001. Recycling of municipal solid waste for cement production: pilot-scale test for
transforming incineration ash of solid waste into cement clinker. Resources, Conservation and
Recycling, 31(2), pp.137-47.
Michael A. Nisbet, M.L.M.M.G.V., 2002. Environmental Life Cycle Inventory of Portland Cement
Concrete. Portland Cement Association.
Napoleon S. Momodu, K.O.D.J.E.D., 2011. Mitigating the Impact of Solid Wastes in Urban Centres
in Nigeria. J Hum Ecol, 34(2), pp.125-33.
Nickolaos Chatziaras, C.S.P., 2016. Use of waste derived fuels in cement industry: a review.
Management of Environmental Quality, 27(2), pp.178-93.
O.O. Akinkurolere, J.O.A.O.L.O.O.M.O., 2013. Construction waste recycling in sustainable
engineering infrastructural development. International Journal of Development and Sustainability,
2(2), pp.1066-74.
Olajumoke F. Kayode, C.L.E.R.R., 2018. Management Recommendations for Improving
Decentralized Wastewater Treatment by the Food and Beverage Industries in Nigeria. environments,
12 March. pp.1-16.
Patel, N.K., n.d. Cement Manufacture. Online Available at:
http://nptel.ac.in/courses/103106108/Lecture%2024.pdf Accessed April 2018.
Potgieter, J.H., 2012. An Overview of Cement production: How “green” and sustainable is the
industry? Environmental Management and Sustainable Development, 1(2), pp.14-37.
Priyanka Pathak, S.G.G.S.D., n.d. Sustainable Waste Management: A Case Study of Cement Industry.
Malaviya National Institute of Technology, Jaipur.
Svoboda, S., 1995. Note on Life Cycle Analysis. Michigan: National Pollution Prevention Center for
Higher Education, University of Michigan.

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