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Use of alternative fuels in cement industry

  • University of West Attica, Greece

Abstract and Figures

Cement production has advanced greatly in the last few decades. The traditional fuels used in traditional kilns include coal, oil, petroleum coke, and natural gas. The substitution of fossil fuels by alternative fuels (AF) in the production of cement clinker is of great importance both for cement producers and for society because it conserves fossil fuel reserves and, in the case of biogenic wastes, reduces greenhouse gas emissions. In addition, the use of alternative fuels can help to reduce the costs of cement production. Energy costs and environmental concerns have encouraged cement companies worldwide to evaluate to what extent conventional fuels can be replaced by waste materials, such as waste oils, mixtures of non-recycled plastics and paper, used tires, biomass wastes, and even wastewater sludge. The clinker firing process is well suited for various alternative fuels; the goal is to optimise process control and alternative fuel consumption while maintaining clinker product quality. The potential is enormous since the global cement industry produces about 3.5 billion tons that consume nearly 350 million tons of coal-equivalent fossil and alternative fuels. This study has shown that several cement plants have replaced part of the fossil fuel used by alternative fuels, such waste recovered fuels. Many years of industrial experience have shown that the use of wastes as alternative fuels by cement plants is both ecologically and economically justified.
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Proceedings of the 12th International Conference on Protection and Restoration of the Environment
Editors: A. Liakopoulos, A. Kungolos, C. Christodoulatos, A. Koutsopsyros
ISBN 978-960-88490-6-8
Use of alternative fuels in cement industry
N. Chatziaras1, C.S. Psomopoulos 1, 2*, N.J. Themelis2
1T.E.I. Piraeus, Dept. of Electrical Engineering, 250 Thivon str & P. Rali Ave, GR-12244, Egaleo, Greece
2Global WTERT Council and Earth Engineering Center, Columbia University, 500 West 120th St., #925,
New York, NY 10027, U.S.A.
*Corresponding author: E-mail:, Tel +302105381182, Fax: +302105381321
Cement production has advanced greatly in the last few decades. The traditional fuels used in
traditional kilns include coal, oil, petroleum coke, and natural gas. The substitution of fossil fuels by
alternative fuels (AF) in the production of cement clinker is of great importance both for cement
producers and for society because it conserves fossil fuel reserves and, in the case of biogenic
wastes, reduces greenhouse gas emissions. In addition, the use of alternative fuels can help to
reduce the costs of cement production. Energy costs and environmental concerns have encouraged
cement companies worldwide to evaluate to what extent conventional fuels can be replaced by
waste materials, such as waste oils, mixtures of non-recycled plastics and paper, used tires, biomass
wastes, and even wastewater sludge. The clinker firing process is well suited for various alternative
fuels; the goal is to optimise process control and alternative fuel consumption while maintaining
clinker product quality. The potential is enormous since the global cement industry produces about
3.5 billion tons that consume nearly 350 million tons of coal-equivalent fossil and alternative fuels.
This study has shown that several cement plants have replaced part of the fossil fuel used by
alternative fuels, such waste recovered fuels. Many years of industrial experience have shown that
the use of wastes as alternative fuels by cement plants is both ecologically and economically
Keywords: alternative fuels, municipal and industrial waste, cement industry, cement production, raw
Cement is the key construction material for global housing and infrastructure needs. The cement
industry worldwide is facing growing challenges in conserving material and energy resources, as
well as reducing its CO2 emissions. Cement producers are striving to increase energy efficiency and
also the use of alternative raw materials and fuels. Therefore the use of alternative fuels has already
increased significantly, but potential for further increases still exists [1].
The role of the cement industry in resource conservation and environmental protection has
increased in recent years because of the rapid economic growth of large regions, such as China,
India and Southeast Asia [2]. The cement industry is an energy-intensive industry with energy
typically accounting for 30–40% of production costs. Figure 1 presents the distribution of electricity
demand in each stage of the cement production process. The energy consumption is estimated at
approximately 2% of world total, and 5% of industry total. The fuel mix in the industry is carbon
intensive, and the calcination process itself produces CO2, so that in total the cement industry
contributes 5% of the global CO2 emissions [1,3].
The 2008 production of cement in the European Union was 200 Mt, approximately 7% of the world
production. In Europe, 158 Mt of CO2 were emitted in 2008 from cement plants which corresponds
to 38.5% of all industrial emissions in Europe or 3.2% of the total European CO2 emissions. In a
modern cement plant, 60% of the CO2 emitted by a cement plant results from the calcinations of
limestone, 30% from combustion of fuels in the kiln and 10% from other downstream plant
operations [4].
Figure 1 Use of electrical energy in cement production [1,4]
Energy efficiency improvements (use of energy efficient equipment, process modifications, etc.),
fuel switching to waste as alternative fuel, and, cement blending using industrial by-products have
helped decrease the CO2 emissions associated with energy conversion [1-4]. This paper presents a
review of the basic alternative fuels used in cement industry.
2.1 Classification of alternative fuels
Cement kilns use different sources of energy to produce the high temperatures necessary for the
formation of clinker. The most common sources of fuel for the cement industry are: coal, fuel oil,
petroleum coke, and natural gas [5].
Alternative fuels are another source of energy used by cement producers around the world. These
fuels are usually derived from the mixtures of industrial, municipal and hazardous wastes [6].
Alternative fuels used in cement industries can be solid or liquid. They are required to have an
appropriate chemical content depending on the type of components and their organic contents.
There are four groups of solid alternative fuels [3].
These fuels generally include:
Agricultural biomass residues
Non-agricultural biomass residues
Petroleum based wastes
Miscellaneous wastes and
Chemical and hazardous wastes
The main part of fuel consumption, and consequently CO2 generation, takes place in the calciner
and clinker forming kiln. The utilization of low-carbon content fuel with high hydrogen-to-carbon
(H/C) ratio instead of conventional fossil fuels can remarkably diminish the rate of CO2 emissions
in the process. In addition to producing a smaller amount of CO2, the use of alternative fuels has
been shown to improve refractory life and also reduce pressure drop in preheater tower [7].
Various types of alternative fuels can be used in a cement plant, with the adequate equipment
installed for the utiliszation. The use of alternative fuels in cement plants also reduces emissions
from landfills [8]. Therefore, it has been estimated that the utilization of this type of fuel will
increase at the rate of 1% per year worldwide [1,6,7,9].
2.2 Alternative fuels
Alternative fuel utilization in the cement industry started in the 1980s. Starting in calciner lines, up
to almost 100% alternative fuel firing at the pre-calciner stage was very quickly achieved.
Alternative fuels are mainly used tires, animal residues, sewage sludges, and waste oil, as can be
seen in Table 1. The last are solid recovered fuels retrieved from industry waste streams, and to a
growing extent also from municipal sources. These refuse-derived fuels are pre-treated light
fractions processed by mechanical or air separation. Waste-derived fuels consist of shredded paper,
plastics, foils, textiles and rubber and also contain metal or mineral impurities. Alternative fuel
utilization in cement kilns is still progressing. While in some kilns up to 100% substitution rates
have been achieved, in others, local waste markets and permitting conditions do not allow for
higher rates of AFR. In any case, AFR utilization requires the adaptation of the combustion process.
Modern multi-channel burners designed for the use of alternative fuels and thermograph systems
allow control of the flame shape to optimize the burning behavior of the fuels and the burning
conditions for the clinker. Table 2 presents the calorific values of varius fuels used in cement
industry, while figure 2 presents a comparison with fossil fuels [9-12].
Table 1 Alternative fuels options for the cement industry [1, 9-12]
Liquid waste fuels Solid waste fuels Gaseous waste
petrochemical waste battery c ases Landfill gas
asphalt slurry plastic residues pyrolysis gas
paint waste wood waste
Petroleum coke rubber residues
Table 2 Wastes used for alternative fuel sources and their energy content [11, 12]
Wastes Energy (MJ/kg)
Used tir e 23.03
Husk 19.93
Industrial plastic 18.21
Waste oil 14.65
Scrap paper 14.23
Contaminated wast e 14.23
RDF plastic 11.72
Sewage s ludge 8.37
Figure 2 Comparison of the calorific values of various alternative fuels [3, 9, 10]
2.2.1. Refuse derived fuel (RDF)
The product of municipal solid waste (MSW) processing is typically referred to as “refuse derived
fuel” (RDF), and is a common fuel alternative in many European countries. Italy, Belgium,
Denmark and The Netherlands are among the countries that have at least one cement kiln
processing RDF. MSW must be sorted to remove there cyclable and inert, and sometimes wet
fractions before it is input into cement kilns. The remaining material accounts for about 20–50% of
the original MSW weight can be incinerated directly or pelletized. Using RDF as a supplemental
fuel in cement production is an economically viable option to minimize fuel costs and landfill
disposals. The effect of using RDF on economy is changing with the cost of capital, coal and
landfill disposal prices [12-14].
There are many advantages of RDF such as minimizing CO2 emission and ash residue, producing
more homogeneous fuel, having higher calorific value content and a lower moisture content. It is
reported that for a net carbon offset through the replacement of coal with RDF, water content must
be less than 15% and in this case net reduction in emissions is obtained as 0.4 tons CO2/ton coal
[15].The basic issue regarding the use of RDF by cement kilns is the chlorine content since chlorine
weakens the cement and increase the risk of corrosion of steel bars in reinforced concrete structures.
Alternative fuels that have high amount of chloride like PVC should be used in limited amounts and
fuel mix optimization is very critical in terms of sufficient heat value in kiln and cement quality [16,
The utilisation of RDF in cement industry is common practice since 1993 in EU while in Austria,
Belgium, Denmark, Italy and Netherlands are some of the indicative countries. According to
literature [18] around 115,000 tpa of MSW were co-incinerated in cement kilns in Europe in 1997
and more than 300,000 tpa of RDF in 2003 [18]. Also in Turkey according to a recent publication
[19] the target for a single cement plant is 35000t/y the usage of RDF [18, 19].
2.2.2. Tire derived fuel (TDF)
Tires are one of the most promising alternatives to the traditional fuels used in the incineration
process in the cement industry. The high temperature in a cement kiln ensures the complete
destruction of end-of-life tires (ELT). Moreover, tires are one of the most powerful alternative fuels
because of their high energy content (above 30 MJ/kg), low degree of material diversification, and
low moisture levels. The technical, environmental and economic viability of using tires in cement
manufacturing processes has been analysed in recent years [17, 20]. Consequently, it is
demonstrated that the amount of coal or petcoke required is reduced and thus the costs associated
with their use is also reduced. In regards to atmospheric emissions of GHGs and pollutants, it is
observed that the CO and total hydrocarbon emissions from the combustion of ELT-fuel mixtures
are slightly higher compared to those from non-ELT firing kilns. [17, 20].
The environmental benefits of utilizing scrap tires as a supplemental fuel in the Portland cement
manufacturing process are multifold. When whole tires are combusted in cement kilns, the steel
belting which is the wire mesh supporting the rubber tire becomes a component of the clinker,
replacing some or all of the iron required by the manufacturing process [15]. Since tires contain no
component deleterious to the quality of cement and, as proven from long experience in checking the
quality of the product, there is no change in the quality of cement caused by feeding tires.
Combustion residues of both tire and steel are not found in the finished cement [15]. None of the
differences in the emission data sets between tire derived fuel (TDF) versus non-TDF firing kilns
for sulfur dioxide, nitrogen oxides, total hydrocarbons, carbon monoxide, and metals were
statistically significant [12, 15, 22].
Many studies conducted by the U.S. governmental agencies and engineering consulting firms have
also indicated that TDF firing either reduces or does not significantly affect emissions of various
contaminants from cement kilns [22]. Tires have some limitations when they are introduced into the
kiln directly because of the large quantity of Zn that remains in the ashes, which can modify the
cement composition dramatically. To avoid this problem, replacement ratios under 30% are
suggested for the kiln fuel [23].
TDF is one of the most commonly used AF in the cement industry in Europe with regular utilisation
in 10 countries across EU. In Finland, Luxembourg and Portugal, TDF is the only AF utilised in
cement kilns. According to literature [18] around 550,000 tpa of TDF is co-incinerated in cement
kilns in Europe. Also in Turkey according to a recent publication [19] a single cement company
have disposed 12.2 millions of scrap tires within last 7 years in three kilns [18, 19].
2.2.3 Sewage sludge
The disposal of sewage sludge generated for sewage treatment plants is causing an important waste
management problem. Cement companies are able to use sewage sludge with calorific energy
potential as one of the alternative fuel sources. Therefore, dried sludge is also used as an alternative
fuel in its rotary kilns.The use of sewage sludge does not generate additional emissions also of all
proven technologies the co-processing of sewage sludge in a cement kiln offers the largest reduction
of CO2 equivalents per ton of dry sludge [24].
Sewage sludge (SS) has high water content. This is an important aspect to be considered when SS is
used in gasification and, especially, in combustion processes. The SS is dried before being used as
an alternative fuel or raw material and the cost of this process is important. Normally, SS is dried
using the waste heat from the cement kiln. It is placed in the main furnace of the cement kiln and
burned as a fuel, or it is gasified beforehand and the gas produced is used as an alternative fuel in
cement kilns, heaters, or pre-calciners. In both cases, the residual non-combustible components of
the sludge are used as raw materials in cement production. If utilized properly, sewage sludge
creates very little to zero environmental impacts [11, 24].
Dewatered SS is utilised in the Europe’s cement industry in 3 countries at least. According to
literature [18] around 50,000 tpa of SS is co-incinerated in cement kilns in Europe. Also in Turkey
according to a recent publication [19] a single cement company is using 45000 tons of SS annually.
[18, 19].
2.2.4. Municipal solid waste (MSW)
MSW production is increasing notably in Europe, and MSW has become a common alternative fuel
in the cement industry. However, most cement plants do not directly burn unsorted MSW due the
heterogeneous nature of the waste and the presence of components that could pose quality and
environmental concerns. Istead they use RDFs like the ones mentioned above. The RDFs from
MSW have different physical and chemical properties depending on their sources, especially with
respect to their ash, chlorine, sulphur, and water contents. There are notable differences among
RDFs, and certain physical and chemical properties can cause difficulties in the kiln combustion
process in cases where the RDF is introduced directly [6, 10, 12, 18].
2.2.5. Waste Derived Fuel PASr
Waste Derived Fuel named PASr is a product used in Malogoszcz Cement Plant, located in Poland.
This fuel is produced by shedding the following types of waste to a grain size of 0-70 mm or 0-40
mm: paper, cardboard, foil, cloth, textile, plastic containers, tapes, cables and cleaning agent. The
waste may be contaminated with oil, fat, lubricants, paint, etc. The fuel is characterised by the
following quality parameters:
1. average heating value—24 MJ/kg (value dependent on fuel composition)
2. average humidity content—3.19%
3. average ash content—7.98%
4. average chlorine content—0.42%
5. average sulphur content—0.23%
PASr fuel was fed to the furnace inlet and through the main burner of the furnace. The tests had
positive results despite the technical and technological problems which occurred. After the tests
were conducted, the following was noted:
1. An increased CO2 content in emissions when the fuel is fed to the furnace inlet, hence the fuel
must be fed to the main burner of the furnace
2. The content of the main oxide components and the phase composition of clinker produced
during the tests of PASr fuel is similar to clinkers produced without the addition of the fuel.
3. Emissions to air, meeting the requirements of the approval decision
After the appropriate installations have been constructed, the fuel will be fed to the furnace through
the main burner (since June 2002). The target combustion will amount to ca.45 thousand tonnes of
fuel annually [6, 25].
2.2.6. Waste Derived Fuel PASi
Waste Derived Fuel named PASr is a product used in Malogoszcz Cement Plant, located in Poland.
The fuel is the result of mixing the sorbent, in the form of sawdust or tobacco dust, with waste
originating from paint, varnish, heavy post-distillation fractions, diatomaceous earth contaminated
with petroleum-based waste, etc. The fuel is characterised by the following quality parameters:
1. average heating value —9.1 MJ/kg (value dependent on fuel composition)
2. average humidity content—30.45%
3. average ash content—24.13%
4. average chlorine content—0.24%
5. average sulphur content —0.28%
The PASi alternative fuel was fed to the lift chamber of the furnace. The tests had positive results
despite, as in the case of the PASr fuel, the technological problems. As in the case of PASr, it was
stated that the content of the main oxide components and the phase composition of the clinker
produced during the tests on the combustion of PASr fuels are similar to those for clinkers produced
without the addition of the fuel. The target is to burn ca. 35 thousand tones of the alternative fuel
(PASi) annually [6, 25].
3.1 Adaptability of alternative fuels
The burning of various types of wastes requires the detailed control and adaptation of technological
processes to each type of waste. For this reason, alternative fuels are derived from wastes having
similar composition and properties. Following properties should be examined before the burning of
alternative fuels is undertaken:
physical state of the fuel (solid, liquid, gaseous),
content of circulating elements,
toxicity (organic compounds, heavy metals),
composition and content of ash,
volatile content ,
calorific value,
physical properties (scrap size, density, homogeneity),
grinding properties,
humidity content,
Proportioning technology.
As a mixture of various wastes, alternative fuels must be produced in conformity with certain rules.
The chemical quality of the fuel must meet regulatory standards assuring environmental protection,
is the first rule. The calorific value must be stable enough to allow the control of the energy supply
to the kiln, the objective being to arrive at a fairly homogeneous composition, and the physical form
must allow easy handling of the material for transportation and a stable, adjustable flow of material
in the cement plant [12, 26, 27].
3.2 Benefits of burning alternative fuels
3.2.1. Ecological benefits
Several years of experience with the use of waste as alternative fuels by the cement industry have
shown that their application is justified both from an economic and an ecological point-of-view.
Firstly, the reduction of the use of non-renewable fossil fuels such as coal as well as the
environmental impacts associated with coal mining. Furthermore, the contribution towards a
lowering of emissions such as greenhouse gases by replacing the use of fossil fuels with materials
that would otherwise have to be incinerated with corresponding emissions and final residues. All
the energy is used directly in the kiln for clinker production [1, 14, 18, 26].
The use of alternative fuels in cement furnaces is also dictated by the broadly understood term
environmental protection, as not only primary sources of energy are spared, but also waste is used,
which would otherwise have to be disposed of on waste disposal sites, or burnt in specially
constructed incineration plants. Application of alternative fuels made from waste may allow one to
reduce the amount of waste to be disposed of by up to 50%. Both incineration plants and waste
disposal sites may have significant negative impacts on components of the environment. One must
be aware that the acquisition of primary sources of energy also negatively influences the
environment [1, 14, 18, 22, 26].
3.2.2. Technological benefits
Flame temperature at 2000C and material temperature at around 1400C which together with
residence time of 4–5 seconds in an oxygen rich atmosphere ensures destruction of organic
components in any residues .The neutralization of any acid gaseous formed during combustion by
the alkaline nature of raw material and subsequent incorporation in the clinker. Interaction of flue
gases and the raw material present in the kiln ensures that the non-combustible part, if any is
reduced. On total life cycle concept, it is superior in comparison with the specialized incinerator or
any other mode. There are many social benefits such as the implementation in rural area would
contribute to overall development of the area and employment. In addition generates additional
revenue for economically backward and frequent drought affected farmers of the region and aids
rural upliftment & ameliorating their economic status [1, 18, 22, 26].
3.2.3. Economic benefits
The use of alternative fuels by the cement industry is related to the energy-consuming process of
clinker production. On average, the energy required for the production of one tonne of cement
amounts to some 3.3 GJ, which corresponds to about 120 kg of coal. The costs of energy consist
about 30–40% of the total costs of cement production. Applications of alternative fuels will
therefore allow one to reduce the production costs. The use of fuels made from waste in cement
plants results not only in financial benefits for the industry, but also for society. Owing to such
waste management, smaller quantities of waste will be disposed of in, or directed to, incineration
plants. This will lead to a reduced number of new disposal sites, a limitation of the expansion of
existing sites and will avoid the necessity to build incineration plants [1, 2, 18, 26].
Many years of experience have shown that the use of wastes as alternative fuels by cement plants is
both ecologically and economically justified. The use of alternative fuels will help reduce the costs
of cement production. The average energy demand for the production of 1 ton of cement is about
3.3. GJ, which corresponds to 120 kg of coal with a calorific value of 27.5 MJ per kg. Energy costs
account for 30–40% of the total costs of cement production. The substitution of alternative fuels for
fossil fuels will help reduce energy costs, providing a competitive edge for a cement plant using this
source of energy. Furthermore, less waste will have to be dumped or burnt, which will mean less
dumping sites. Therefore, the use of waste-derived alternative fuels by cement plants will be also
beneficial to the environment. The conditions in rotary kilns, such as high temperature, the high
speed of the gas stream and the long particle-storage period, guarantee that the use of alternative
fuels is ecologically safe. Co-processing in the cement industry is the optimum way of recovering
energy and material from waste. It offers a safe and sound solution for society, the environment and
the cement industry, by substituting non renewable resources with societal waste under strictly
controlled conditions. The desired waste material, to be used as a fuel, is available within the state.
The cost of waste being used as fuel does not exceed the cost of fossil fuels.
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... increase of the energy efficiency in OPC production process due to the implementation of modern technologies for preparing raw materials for clinker burning while using the dry method and the resignation from the more energy-consuming and outdated wet method, e.g., [56], • improvement of energy efficiency in the context of a significant reduction of thermal energy consumption in OPC production process, e.g., [18][19][20][21][22], • capturing and storage of CO 2 , e.g., [49,56,57], • increase in the share of alternative fuels to replace coal and coke in the cement kiln firing process, e.g., [9,40,[58][59][60][61][62], and • replacing clinker in cement by other mineral or non-mineral components (e.g., fly ash, furnace slag, silica fume, and others), referred to as supplementary cementitious materials (SCMs), e.g., [63][64][65][66][67][68][69][70][71][72][73][74]. ...
... Alternative fuels are another source of energy used by cement producers around the world. They can replace the basic sources of energy used by cement kilns to produce the high temperatures that are necessary for the formation of clinker, such as: coal, fuel oil, petroleum coke, and natural gas [61]. These fuels are usually derived from the mixtures of industrial, municipal and hazardous wastes [53]. ...
... Alternative fuels used in cement industries can be solid or liquid. They are required to have an appropriate chemical content, depending on the type of components and their organic contents [61]. ...
Full-text available
The paper presented herein investigates the effects of using supplementary cementitious materials (SCMs) in quaternary mixtures on the compressive strength and splitting tensile strength of plain concrete. In addition, environmental benefits resulting from the proposed solutions were analysed. A total of four concrete mixtures were designed, having a constant water/binder ratio of 0.4 and total binder content of 352 kg/m3. The control mixture only contained ordinary Portland cement (OPC) as binder, whereas others incorporated quaternary mixtures of: OPC, fly ash (FA), silica fume (SF), and nanosilica (nS). Based on the obtained test results, it was found that concretes made on quaternary binders containing nanoadditives have very favorable mechanical parameters. The quaternary concrete containing: 80% OPC, 5% FA, 10% SF, and 5% nS have shown the best results in terms of good compressive strength and splitting tensile strength, whereas the worst mechanical parameters were characterized by concrete with more content of FA additive in the concrete mix, i.e., 15%. Moreover, the results of compressive strength and splitting tensile strength are qualitatively convergent. Furthermore, reducing the amount of OPC in the composition of the concrete mix in quaternary concretes causes environmental benefits associated with the reduction of: raw materials that are required for burning clinker, electricity, and heat energy in the production of cement.
... Cement production depends mainly on coal as an energy source, however, alternative fuels such as biomass and hazardous wastes are being used in increasing utilization ratios since the 1980s [9][10][11]. Co-combustion of Graphic abstract alternative fuels for cement production in Europe by 2021 represents 43% of total energy input compared to 15% in North America and 8% in China [12]. ...
... Biomass and RDF (Refuse Derived Fuel) are the main alternative fuels used by cement producers globally [11,13]. Biomass is a common definition for the organic, carbon-based, material and waste from pets and plants that reacts with oxygen in combustion and natural metabolic processes to release heat [14][15][16]. ...
... According to Chatziaras [11], there was a net reduction of the carbon dioxide emissions (~0.4 tons CO 2 /ton of coal substitution) where the moisture content of RDF was less than 15% when using in clinker production. Zhang [29] reported that traditional RDF chlorine content is between 0.36% and 1.29% which limits the total substitution ratio to 54% of thermal energy. ...
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Cement clinker production in Egypt till 2013 relied mainly on fossil fuel as a primary energy source. However, with multiple fossil fuel shortages, the utilization of biomass wastes was initiated by multiple cement producers. In the current work, and to present an industrial-scale biomass and coal co-combustion study, the utilization of multiple biomass fuels to substitute a portion of bituminous coal was studied in an Egyptian clinker production plant. Mixtures of biomass fuels were used to reduce the consumption of bituminous coal and to investigate the diminishing of the environmental impact of the clinker production process. The current study was conducted during 8 days of the stable clinker production process by replacing 14% of bituminous coal with biomass mixtures while monitoring the major process control parameters and resulting emissions. Emission results were compared to the nation’s regulations. A conclusion can be made that using biomass mixtures as alternative fuels minimized the dependency on coal as the main fuel and reduced the CO2 burden of the cement production process. In addition, NOx and SO2 emissions were declined while CO emissions were increased by utilizing biomass mixtures as alternative fuels; all emissions, however, were below the allowable limits stated by the Egyptian environmental authority. Noticeably, the heavy elements, dioxins, and furans were not changed significantly compared to those produced using coal only.
... The heavy use of traditional fuels (coal) in the South African cement kiln can be replaced with alternative fuels, for example, waste-derived fuels. Using waste-derived fuels instead of traditional fuel reduces emissions and fossil resources used in the cement industry, making it a sustainable method for recycling various waste materials [111,112]. Hence, it could be agreed that the choice of materials and fuels directly influence the relationship between the cement plant and the environment. ...
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The cement industry confronts significant challenges in raw materials, energy demands, and CO2 emissions reduction, which are global and local environmental concerns. Life cycle assessment (LCA) has been used in many studies to assess the environmental impact of cement production and investigate ways to improve environmental performance. This study aims to analyse the environmental impact of Portland cement (CEM I) on the South African cement industry using the life cycle impact assessment (LCIA), based on the Recipe 2016 v 1.04 midpoint method. The study was conducted using data modeled after the South African cement plant, considered a cradle-to-gate system boundary, starting from the extraction of the raw material to the cement production process that produces cement as the main product. The data were obtained from the Ecoinvent database v3.7.1, integrated with SimaPro 9.1.1. software, used to assess the impact categories. For simplicity, the study merged the entire production process into five processes, i.e., raw materials usage, fuel consumption, clinker production, transportation and electricity. The impact categories of the five production stages were assessed using the LCA methodology. The impact categories investigated were classified into three categories: atmospheric, resource depletion and toxicity categories. According to the results, clinker production and electricity usage stages contribute the most to atmospheric impact (global warming, which causes climatic change due to high CO2 emissions), followed by raw materials and fuel consumption, contributing to the toxicity and resource depletion impact category. These stages contribute more than 76% of CO2 eq. and 93% of CFC-11 eq. In the midpoint method, CO2 is the most significant pollutant released. Therefore, replacing fossil fuels with alternative fuels can reduce fossil fuel use and the atmospheric impact of cement kilns.
... Caranya dengan menggunakan alternatif bahan bakar lainnya yang lebih murah dari batubara, ramah lingkungan dan terbarukan. Industri semen di seluruh dunia menghadapi tantangan yang semakin besar dalam melestarikan sumber daya material dan energi, serta mengurangi emisi CO2 [29] [30]. Peran industri semen dalam konservasi sumber daya dan perlindungan lingkungan telah meningkat dalam beberapa tahun terakhir karena pertumbuhan ekonomi yang cepat di kawasan besar, seperti Cina, India, dan Asia Tenggara. ...
Conference Paper
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Present, it is important to limit using and burning of fossil fuels (biodiesel) such as coal because it is not renewable and expensive, then switch to biomass. Indonesia potential to produce abundant biomass as renewable energy and can be used to replace coal due to favorable geography and climate. Biomass used is coffee grounds waste.It comes from one of a company wastes engaged in the processing of coffee drinks (Arabica and Robusta types) located in Tangerang, Indonesia. The research purpose is to obtain the utilization of coffee grounds waste as a cheap and potential alternative fuel for industry, and reduce coffee grounds waste itself. Coffee grounds waste is spread out and monitored for several days in an open area but under the roof so that water content is maintained (water content & calories are tested). The results show that the calorie content of coffee grounds waste can reach 4840 kcal/kg, total water content reaches 11.86%, ash content reaches 2.01% and sulfur content reaches 0.27%. Calorific value of coffee grounds waste is higher than that of husks and almost the same as coal. Thus, coffee grounds waste is ready to be used as fuel either directly or mixed with coal. Abstrak Saat ini penting untuk membatasi penggunaan dan pembakaran bahan bakar fosil (biodiesel) seperti batu bara karena bukan energi terbarukan dan mahal, lalu beralih ke biomassa. Indonesia memiliki potensi untuk menghasilkan biomassa yang melimpah sebagai energi terbarukan dan dapat dimanfaatkan untuk menggantikan batubara karena geografis dan iklim yang mendukung. Biomassa yang digunakan adalah limbah ampas kopi. Tujuan dari penelitian ini adalah untuk memperoleh pemanfaatan limbah ampas kopi sebagai bahan bakar alternatif yang murah dan potensial untuk industri, serta mengurangi limbah ampas kopi itu sendiri. Limbah ampas kopi berasal dari salah satu limbah perusahaan yang bergerak di bidang pengolahan minuman kopi (jenis Arabika dan Robusta) yang berada di Tangerang, Indonesia. Limbah ampas kopi dihampar dan dimonitor selama beberapa hari di area terbuka tetapi di bawah atap agar kadar air tetap terjaga (kadar air serta kalornya di tes). Hasil penelitian menunjukkan bahwa kandungan kalor limbah ampas kopi bisa mencapai 2840 kcal/kg, total kadar air bisa mencapai 11.86%, kadar ash mencapai 2.01% serta kadar sulfur mencapai 0.27%. Nilai kalor limbah ampas kopi lebih tinggi dari sekam dan hampir sama dengan batubara. Dengan demikian limbah ampas kopi ini siap dijadikan bahan bakar baik langsung maupun di campur dengan batubara. Kata kunci : ampas kopi, bahan bakar alternative, biomassa, energi terbarukan, kalor
... Conventional fuels, such as coal, pet coke, natural gas, used in the cement kiln can be substituted by alternative fuels such as waste-derived fuels. Examples of the waste materials commonly used as alternative fuels include used tyres, animal residues, sewage sludges, waste oils and other types of waste derived from industrial and municipal sources ( Chatziaras et al., 2014 ). Though several types of waste can be used as alternative fuels, such wastes need to be pretreated before being used in the cement industry. ...
Cement manufacturing is an energy-intensive industry which uses a large amount of resources and contributes environmental impacts at both small and large scales. The growth of key world economies has led to an increase in the use of construction materials and therefore in the demand for cement, particularly in the Asian region. With increasing interest on sustainability issues, environmental concerns posed by the cement industry in Myanmar were investigated in order to explore options to mitigate emissions and subsequent environmental impacts. Comparative life cycle assessments were conducted including a base scenario (existing cement production scheme) and five alternative scenarios developed mostly with a focus on energy efficiency and the use of alternative fuels and materials. A cradle-to-gate system boundary was considered, limiting the scope of the study to raw material extraction, transportation and manufacturing. The impact assessment was performed based on the ReCiPe (2016) method. The results showed that the mitigation options employed in specific scenarios led to a significant reduction in major emissions and consequent environmental impacts in comparison with the base scenario. Above all, the ideal scenario (combination of all possible mitigation options) showed the best results enabling a decrease in emissions of CO2 by 10-50%, NOx by 5-23%, SO2 by 4-20% and PM2.5 by 6-22% compared to a base scenario. This resulted in a reduction of major environmental impacts by 10-50% for climate change, 6-27% for photochemical oxidant formation: ecosystem quality, 7-22% for particulate matter formation, 6-22% for terrestrial acidification and 8-64% for fossil resource scarcity.
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Carbide residue activated blast furnace slag is a relatively new kind of eco-friendly construction materials. This work addresses the design of foamed lightweight concrete as road embankment material using such material. A statistical mixture design approach was adopted to assess the influence of each ingredient as well as the interaction between these on the spreadability and compressive strength and thus allowing mixture design. The fitted models were validated using analysis of variance, residual analysis and confirmed by the experiments. Afterwards, the proposed models were used to optimize the mixture. The mixture with the highest compressive strength and the maximum content of carbide residue that allows the mixture to meet the required properties were obtained, respectively.
This experimental study investigated the use of combined industry by-products, carbide sludge (CS) and ground granulated blast-furnace slag (GGBS), to replace ordinary Portland cement (OPC) for the stabilization of clay slurry, aiming to increase the stabilization efficacy, reduce the cost, and mitigate the environmental impacts associated with OPC production and disposal of industrial by-products. To better understand the stabilization mechanisms, properties of CS-GGBS and OPC stabilized clay slurry are systematically evaluated and compared. Test results indicate that the unconfined compressive strength (UCS) of the optimum CS-GGBS-stabilized clay slurry is 2–4 times that of the corresponding OPC-stabilized clay slurry. However, the strength of OPC paste is 1.3–1.4 times that of the optimum CS-GGBS paste. Due to the ultra-high water content and the active clay minerals, larger amounts of Ca(OH)2 are required to reach the same pH of pore water in stabilized clay slurry specimens than in the paste. This is responsible for the greater optimum CS/(CS + GGBS) ratio in the stabilized clay slurry than in the paste. OPC hydrates much faster and consumes more water than CS-GGBS during specimen preparation, resulting in a much lower void ratio and higher strength of OPC paste. For the stabilized clay slurry, the binder contents are very low and the water-to-binder ratio is hence very high, and thus the effect of binder hydration rate on the void ratio is insignificant. The remarkably different strength discrepancy between both types of stabilized clay slurry is not attributed to the slightly different void ratio, but due to the significantly different microstructures formed in the stabilized materials. The findings in this study contribute to a deep insight into the strength development of stabilized clay-slurry type dredged material.
Portland cement clinker is a very important compound of modern cements. CO2 emission during the calcination of calcium carbonate as raw material takes place in cement plants. Reduction of CO2 emission, the anthropologically caused climate change, is the focus of international initiatives, and hence, finding and development of strong alternatives are the key areas of researchers, policy makers, and plant operators.
This study investigates the use of carbide slag (CS), an industrial by-product generated in acetylene production, as a potential alternative to hydrated lime (HL) for activation of ground granulated blast-furnace slag (GGBS), another industrial by-product generated during the process of iron production. Specimens of CS-GGBS and HL-GGBS pastes with different CS or HL contents were prepared and cured for different periods, and then tested for compressive strength. X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were also used to investigate the hydration characteristics of CS-GGBS. The results indicated that CS-GGBS yielded similar compressive strength as HL-GGBS with the same CS/HL content at the same curing periods of 28 and 56 days, i.e. CS could replace HL to activate GGBS, which would result in both environmental and economic benefits. The Ca(OH)2 in CS accelerated the hydration of GGBS, and hence more hydration products were produced. However, excessive CS addition would decrease the GGBS content and increase crystal calcium hydroxide in the matrix, causing strength decrease. Hence, there was an optimum CS/HL content to achieve the highest compressive strength, which was 10% for 7 days and 5% for 28 and 56 days.
Conference Paper
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Cement is the most manufactured product on earth. Unfortunately, the manufacture of cement is accompanied by the emission of carbon dioxide gas. Among all manufacturing industry sectors in the UK, the cement industry is the largest CO 2 emitter and these emissions are damaging our planet. The sustainable development of cement will allow future generations to develop without being compromised by the cement industry. This work identifies some of the routes to reducing the environmental burden of the cement industry.
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The end of life tyres (ELT) management generates CO 2 -eq emissions due to the involved processes. Therefore, this research has been conducted with the aim of quantifying the environmental performance of an ELT management system, in terms of CO 2 -eq emissions, which includes the recycling operation through the ELT treatment plant, the transport system and the secondary raw material de-rived from ELT processing; apart from other different ELT recovery methods. To this end, the environmental performance method based on life cycle assessment and complemented with the Clarke and Wright's saving algorithm has been de-veloped in order to evaluate and optimise the location of the ELT treatment plants. To validate the proposed method, the Autonomous Community of Aragon in Spain is shown as a case study. Different ELT management scenarios have been analysed for the Aragon's ELT treatment plant and the optimisation of transportation of the baseline scenario is carried out by means of the Clarke and Wright algorithm. By applying the proposed methodology it has been identified that the current location of the Aragonese treatment plant has benefits in net CO 2 -eq emissions for the different radii studied with a maximum of 200 km. On the other hand, The Clarke and Wright method has been applied in order to ob-tain the transportation optimisation of the total travelled distance from the 42 collection/sorting centres to the treatment plant. As a result, the travelled dis-tance can be reduced about 15%.
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The effect of the increasing concentration of CO2 in the atmosphere on climate change is a major driving force for the development of advanced energy cycles incorporating CO2 management options. Growing interest in the technical and economic feasibility of CO2 capture from large coal-based power plants has led to increased efforts worldwide to develop new concepts for greater CO2 reductions in the future. Greenhouse gas emissions, especially CO2, have to be reduced by 50–80% by 2050, according to the IPCC [1].The type of fuel used in cement manufacture directly impacts on CO2 emissions, with coal accounting for around 60–70% of CO2 emissions from cement installations. Therefore, the large amount of carbon dioxide emitted during cement manufacturing process - 5% of the total emissions of CO2 from stationary sources worldwide - is a cause of great concern and has to be tack led in order to comply with current legislation.Several technologies are available and have been proposed for the separation of CO2 from the flue gases from new and existing plants with retrofit capture units. Few studies have been undertaken on CO2 capture in cement plants to assess the suitable technologies, with oxy-combustion and amine scrubbing as the possible options (pre-combustion capture not being viable). This paper summarises the different CO2 capture technologies suitable for cement industry and assesses the potential of the calcium looping cycle [2,3] as a new route for CO2 capture in the cement industry. The potential advantage of this system is the very low efficiency penalty expected (
The production of Portland blast-furnace cement is a process that requires an extraordinary amount of energy. The total energy costs for cement represent around 40% of the total production costs. In many areas such as Germany, there is constant effort among suppliers to reduce the electrical energy consumption of the various machines. On the other hand, the cement producers, are trying on their part, to reduce the absolute costs and specific costs of thermal energy through the use of alternative fuels.
Plant operators are confronted with the need for substitute fossil-based fuels by co-firing alternative fuel in rotary kiln firing systems. A fast development in burner technology has been taking place concerning the firing of multiple fuels with different combustion characteristics. A new burner generation fulfils the requirements of clinker processing with regard to the respective fuels. Alternative fuel co-firing changes the flame shape and temperature profiles in rotary kilns. Thermography systems help to compensate negative effects of alternative fuels by adopting burner setting and possibly increasing the utilisation of alternative fuels.
One of the keys to achieve the sustainable construction goals in green projects is to select appropriate building materials for construction. Such projects aim to use eco-friendly materials that encourage the consumption of recycled and renewable materials, locally manufactured with less harmful gas emis- sions with long and durable profiles. Using these eco-friendly materials is also helpful for obtaining higher rates during the application processes of green building certificates. As the demand for sustain- able materials increases globally, the construction material producers need to supply materials that can be used in environmentally responsible buildings without compromising ecological conditions. In par- ticular, cement production has a huge impact on the environment because of releasing high amount of CO2 during production processes. This paper aims to express the sustainability of building materi- als in Turkish construction industry through analyzing cement production of a Turkish cement company where alternative fuels, raw materials, by-products and energy efficient methods are used for sustainable development.