ArticlePDF Available

Abstract and Figures

Cement production is characterized by extremely high energy consumption per unit of product. Energy costs and environmental standards encouraged cement manufacturers worldwide to evaluate to what extent conventional fuels can be replaced by alternative fuels, i.e., processed waste materials, such as scrap tires. The decisive factors promoting the use of cement kilns for the utilization of scrap tires are: the high incineration temperature, the large area of the furnace, the significant length of the kiln, the long period of time the fuel stays inside the kiln, and the alkaline environment inside the kiln. The use of scrap tires in cement kilns is one of the best technologies for a complete and safe destruction of these wastes, due to the fact that there is a simultaneous benefit of destroying wastes and getting the energy. Thus, the use of scrap tires as alternative fuel in cement kilns has energy and economic justifiability, and it is environmentally friendly. In this article, monitoring results of nitrogen and sulfur oxides emissions from cement kilns in a cement factory in Serbia are given, depending on the ratio of scrap tires in total fuel quantity. Research was carried out for 0 to 15% share of scrap tires in total heat production. Nitrogen and sulfur oxides emission measurements from cement kilns were done during a trial use of scrap tires as a secondary fuel in a cement factory. During nitrogen and sulfur oxides emissions monitoring from the cement kiln, coal and petroleum coke were used as primary fuel, and whole or shredded tires were used as secondary fuel. Experimental results have shown the encouraging results: in particular, clinker characteristics were unmodified, and stack emissions of NOx and SO2 were, in the case of tires, slightly decreased, in some cases were incremented, but remaining always below the law imposed limits.
Content may be subject to copyright.
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=ueso20
Download by: [Zoran Cepic] Date: 10 February 2016, At: 01:04
Energy Sources, Part A: Recovery, Utilization, and
Environmental Effects
ISSN: 1556-7036 (Print) 1556-7230 (Online) Journal homepage: http://www.tandfonline.com/loi/ueso20
Use of scrap tires in cement production and their
impact on nitrogen and sulfur oxides emissions
B. Nakomcic-Smaragdakis, Z. Cepic, N. Senk, J. Doric & Lj. Radovanovic
To cite this article: B. Nakomcic-Smaragdakis, Z. Cepic, N. Senk, J. Doric & Lj. Radovanovic
(2016) Use of scrap tires in cement production and their impact on nitrogen and sulfur oxides
emissions, Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 38:4,
485-493, DOI: 10.1080/15567036.2013.787473
To link to this article: http://dx.doi.org/10.1080/15567036.2013.787473
Published online: 08 Feb 2016.
Submit your article to this journal
View related articles
View Crossmark data
Use of scrap tires in cement production and their impact on
nitrogen and sulfur oxides emissions
B. Nakomcic-Smaragdakis
a
, Z. Cepic
a
, N. Senk
a
, J. Doric
a
, and Lj. Radovanovic
b
a
University of Novi Sad, Faculty of Technical Sciences, Novi Sad, Serbia;
b
University of Novi Sad, Technical Faculty
Mihajlo Pupin, Zrenjanin, Serbia
ABSTRACT
Cement production is characterized by extremely high energy consumption
per unit of product. Energy costs and environmental standards encouraged
cement manufacturers worldwide to evaluate to what extent conventional
fuels can be replaced by alternative fuels, i.e., processed waste materials,
such as scrap tires. The decisive factors promoting the use of cement kilns
for the utilization of scrap tires are: the high incineration temperature, the
large area of the furnace, the significant length of the kiln, the long period
of time the fuel stays inside the kiln, and the alkaline environment inside
the kiln. The use of scrap tires in cement kilns is one of the best technol-
ogies for a complete and safe destruction of these wastes, due to the fact
that there is a simultaneous benefit of destroying wastes and getting the
energy. Thus, the use of scrap tires as alternative fuel in cement kilns has
energy and economic justifiability, and it is environmentally friendly. In this
article, monitoring results of nitrogen and sulfur oxides emissions from
cement kilns in a cement factory in Serbia are given, depending on the
ratio of scrap tires in total fuel quantity. Research was carried out for 0 to
15% share of scrap tires in total heat production. Nitrogen and sulfur oxides
emission measurements from cement kilns were done during a trial use of
scrap tires as a secondary fuel in a cement factory. During nitrogen and
sulfur oxides emissions monitoring from the cement kiln, coal and petro-
leum coke were used as primary fuel, and whole or shredded tires were
used as secondary fuel. Experimental results have shown the encouraging
results: in particular, clinker characteristics were unmodified, and stack
emissions of NOx and SO
2
were, in the case of tires, slightly decreased, in
some cases were incremented, but remaining always below the law
imposed limits.
KEYWORDS
Alternative fuel; cement
industry; nitrogen oxides
emission; scrap tires; sulfur
oxides emissions
1. Introduction
Cement is the main component of concrete, which is, in turn, the second most consumed material
on earth; in addition, the cement industry has one of the most intensive energy consumptions. The
modern plants often have nominal production capacity exceeding one million tons per year (Lamas
et al., 2013). The worldwide production of cement has more than quadrupled over the last 25 years,
reaching 3 million tons in 2009. Production is expected to further increase because of the exponen-
tial growth rates in developing countries, such as China and India, which are the major cement
producersintheworld(Oggionietal.,2011).
It is estimated that the cement industry is responsible for approximately 2% of the worlds
primary energy consumption (Nielsen, 2012). Fossil fuels, such as coal and petroleum coke, have
CONTACT Lj. Radovanovic ljiljap@tfzr.uns.ac.rs University of Novi Sad, Technical faculty Mihajlo Pupin, Djure Djakovic
bb, 23000 Zrenjanin, Serbia.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ueso.
© 2016 Taylor & Francis
ENERGY SOURCES, PART A: RECOVERY, UTILIZATION, AND ENVIRONMENTAL EFFECTS
2016, VOL. 38, NO. 4, 485493
http://dx.doi.org/10.1080/15567036.2013.787473
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
traditionally been used as energy sources in the cement manufacturing industry; however, in recent
decades, these fuels are increasingly being substituted with alternative, typically residue-based sources
(e.g., sorted municipal solid waste, tires, and waste wood) (Albino et al., 2011; Zabaniotou et al.,
2002).
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 main end-markets for scrap tires are tire-derived fuel (TDF); civil engineering applications;
ground rubber applications; and cut, punched, and stamped rubber products.
While tire-derived fuel is the major end-market in most countries at the moment, growth in civil
engineering applications is likely to be much stronger over the long term as the latter is more
profitable. However, in Europe, tire-derived fuel could benefit in the short term. This is because the
demand from civil engineering market takes more time to get established than tire-derived fuel. As
supply takes off the civil engineering market might not be able to absorb the excess supply, some of
which could be diverted for use as fuel.
The average energy demand for the production of one ton of cement is about 3.3 GJ thermal
energy, which corresponds to 120 kg of coal with a calorific value of 27.5 MJ/kg and approximately
110 kWh/t of electrical energy (with 40% directed to clinker grinding) (Mokrzycki and Uliasz-
Bocheńczyk, 2003;Jankovicetal.,2004). Thermal energy accounts for about 2025% of the cement
production cost (Madlool et al., 2011). The main thermal energy is used by burning processes, while
cement grinding consumes electrical energy (Madlool et al., 2013). On average, energy costs, in the
form of fuel and electricity, represent 40% of the total production costs for one ton of cement
(Oggioni et al., 2011). The substitution of fossil fuels with alternative fuels will help reduce energy
costs and therefore production costs, providing a competitive edge for a cement plant using this
source of energy.
The capital costs associated with modifying feed and emission control equipment for TDF
burning in cement kilns are minor in most cases. Therefore, the cost savings from TDF is essentially
equal to the savings in fuel cost by using TDF in the kiln. This fuel cost advantage is attractive to
cement plants because the process is so energy intensive. However, cement kilns can accommodate
many alternate fuels, so that regional availability and price of alternatives may affect the cost
advantage. Because of their consumption, cement plants are able to buy conventional fuels in bulk
and at somewhat lower prices in general.
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. The
energy-intensiveness of cement production processes and increasing fuel prices, combined with fuel
deficit, force the cement industry to search for technologies based on waste-derived and alternative
fuels (Mokrzycki and Uliasz-Bocheńczyk, 2003; Mokrzycki et al., 2003).
The use of fuels made from waste in cement plants results not only in financial benefits for the
industry, but also for society (Mokrzycki et al., 2003). The cement industry may give a significant
contribution to the resolution of a problem, which seriously affects most of the industrialized
countries, namely the continuous growth of wastes that have to be adequately disposed of, e.g.,
scrap tires.
Worldwide, almost one billion tires for passenger cars, utility vehicles, trucks, and off-road
vehicles are manufactured each year, and almost an equal number of tires is permanently removed
from vehicles and defined as waste. On average, approximately one scrap tire per person per year is
accumulated in industrialized countries. Over the years, new amounts are added to the billions of
tires already stored or buried in landfills, as well as at some illegal sites, warehouses, and other fields
around the world.
In the EU alone, approximately 3.5 million tones of passenger car, utility vehicle, and truck tires
become waste each year. Their use as an alternative fuel could provide 112 million GJ of energy and
save 18.5 million barrels of crude oil (ETRA, 2013).
486 B. NAKOMCIC-SMARAGDAKIS ET AL.
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
In Serbia considering that the average lifespan for car tires is about 8 years and that annual
production is approximately 1.1 million pieces or around 15,00018,000 tons and with the additional
value of technical products from rubber industry production there is approximately 30,000 tons of
scrap tires annually. The use of tires as alternative fuels in Serbia could provide one million GJ of
energy and save 160 thousand barrels of crude oil (Djekic et al., 2010).
In fact, the European Directive (directive of the European Union, En 197/1) makes it possible to
use alternative fuels in the clinker kilns. Actually, due to very high temperatures reached (1400°C)
by clinker kiln, the cement industries provide a means to reuse both waste tires and oils, whose
utilization is recommended by the European Union (directive of the European Union, 91/156/CEE,
91/689/CEE, and 94/62) (Prisciandaro et al., 2003).
Utilizing tires as alternative fuel has the following advantages for the cement manufacturing
process:
(1) The cement burning process is a closed system where the dust removed from the exhaust gas
by an electrical precipitator is recycled into charge material. Thus, the ash in tires is not
discharged from the system. Moreover, sulfur contained in tires will be absorbed by the raw
materials of cement and will not create harmful sulphur oxides.
(2) The temperatures within the process will reach a maximum of 1800°C in the burning gas
and about 1500°C in the clinker. Therefore, tires fed to the kiln will burn completely within
a short time.
(3) Tire is composed of rubber, carbon-black, sulfur, and steel. Steel, which is not a combustible
component, will be oxidized and will be transformed into one of the cement components
(Nakajima and Matsuyuki, 1981).
Worn tires, although a particular residual material, are excellent sources of energy, especially
when used as secondary fuels. Tires can be completely destroyed in the rotary kiln due to the
characteristics of these devices that combine extremely high temperatures with an oxidizing atmo-
sphere and a residence time of material relatively long. The complete combustion prevents the
formation of soot or odors.
Tires are composed of about 88% of carbon and oxygen, which have a very low heating value
of about 32 MJ/kg, and burn quickly. The high calorific value of the tires contribute to lower
consumption of non-renewable fuels (coal and oil), thus saving natural resources (Lamas et al.,
2013).Buttheuseoftireasafuelislimitedtoamaximumof30%forcementindustrydueto
the presence of heavy metals in their composition, mainly zinc. This has the effect of lowering the
initial resistance, but ensures higher final strength of the cement (Bhatty, 1995; Pipilikaki et al.,
2005).
In this article, monitoring results of nitrogen and sulfur oxide emissions from cement kilns are
given, depending on the tires share in total amount of fuel. Research was carried out in the cement
industry in Serbia with a dry method of clinker production with tires heat ratio in fuel from 0
to 15%.
2. Dosage of scrap tires as a secondary fuel in cement production
Fuel dosage in rotary kilns with pre-heater is done through the main burner at the front of a rotary
kiln (primary dosage) and at the transition between pre-heater and rotary kiln (secondary dosage).
Primary dosage involves inserting fuel into the sintering zone through the main burner, and this
area is also called the primary combustion zone. For optimal adjustment of the flame from the
standpoint of using coal as a primary fuel and different requirements from the standpoint of raw
material quality, burners with adjustable flame are used. These burners have the option of separate
or simultaneous injection of fuel, such as pulverized coal; petroleum coke; fuel oil; natural gas; and
so-called alternative fuels, such as pulverized plastics, waste oil, etc.
ENERGY SOURCES, PART A: RECOVERY, UTILIZATION, AND ENVIRONMENTAL EFFECTS 487
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
Secondary fuel dosage in a rotary kiln is implied to be fuel injection that is not done through the
main burner. A secondary dosage system is usually used for alternative fuel dosage, such as tires.
Tires are dosed into the flue gas chamber where flue gas temperatures are around 1000°C, and
material temperatures are up to 800°C. After insertion into the flue gas chamber, tires go to the
rotary kiln where they start to burn, and then carried with material leave to the zones with higher
temperatures where they are completely burned. Organic components are entirely burned in the
calcinations zone, i.e., in areas where the temperature of flue gases is between 1100 and 1200°C, and
for material around 900°C. Oxidation of inorganic components occurs in the transition and sinter
zone of the kiln. In these zones oxides are incorporated into the clinker structure.
Figure 1 shows the simplified scheme of rotary kiln with marked movement directions and
temperatures of materials and hot gases, and the place of introducing secondary fuel into the flue
gas chamber.
In Table 1 some basic technical parameters of rotary kilns for cement production are given.
Figure 1. Simplified scheme of rotary kiln with marked place for tire dosage. © Svetlana Pavić. Reproduced by permission of
Svetlana Pavić. Permission to reuse must be obtained from the rightsholder.
Table 1. Basic technical parameters of rotary kiln (Arhitekt AD, 2007).
Characteristic Unit Value
Nominal length m 60.0
Diameter of the combustion zone m 4.8
Diameter of the calcination zone m 4.8
Diameter at the junction with the flue gas chamber m 5.0
Slope % 3.5
Capacity t/dan 4,000
Installed operating power kW 2 × 450
Maximum rotation speed min
1
4
Specific electricity consumption kW/t 3
© Svetlana Pavić. Reproduced by permission of Svetlana Pavić. Permission to reuse must be obtained from the rightsholder.
488 B. NAKOMCIC-SMARAGDAKIS ET AL.
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
3. Experiment description and selection of measuring points
It is foreseen that, during experimental study, dosage of tires is conducted by two trailer channels
with dual movable partitions. Movable partitions are placed one below the other on the same side of
the channel. They are opened and closed pneumatically by four cylinders. One connection channel is
for the whole, and the other one for shredded tires. Capacity of connection channels is 5 t/h of tires.
Measuring nitrogen and sulfur oxides emissions from a rotary kiln occurred throughout the trial
(limited) use of tires as secondary fuels in a cement factory, while referential measurement of
emission was conducted without the use of the tire. Position of measurement points was determined
in accordance with the standards and methods anticipated for this type of measurements and
working conditions in the facility, i.e., in accordance with ISO 9096:2003. Measurement points
were chosen so that they could realistically reflect the actual state of nitrogen and sulfur oxides
emissions in the air.
Measurement points for nitrogen and sulfur oxides emission measuring during the combustion of
coal, petroleum coke, and scrap tires in a rotary kiln are the following:
Chimney of the kiln after bag filter (measuring point 1: MP1);
Chimney after electrofilter of raw material drier (measuring point 2: MP2).
At the emitter (chimney) measuring point with circular cross-section, laminar air flow was
provided, which is in accordance with ISO 9096:2003. Key features of the bag filter after rotary
kiln and also emitter characteristics are shown in Table 2. The main characteristics of an electrofilter
of raw material drier and emitter are shown in Table 3.
Nitrogen and sulfur oxides emission measurement at point 1 was performed at the vertical section
of flue gas duct at a height of approximately 30 m, and emission measurements at point 2 were
carried out at the vertical section of flue gas duct at a height of approximately 42 m. At both
sampling points, nitrogen and sulfur emission measurements were conducted in accordance with
Table 2. Characteristics of rotary kilns bag filter and emitter (measuring point 1).
Bag filter
1. Filter type Bag
2. Ventilator type Radial
3. Number of chambers 10 (300 bags in every chamber)
4. Rotation speed (possibility of regulation) 740 min
1
5. Under pressure Constant
6. Ventilator capacity 450,000 m
3
/h
Emitter (measuring point 1)
1. Emitter height 40.3 m
2. Diameter 4.002 m
© Svetlana Pavić. Reproduced by permission of Svetlana Pavić. Permission to reuse must be
obtained from the rightsholder.
Table 3. Characteristics of electrofilter of raw material drier and emitter (measuring point 2).
Electrofilter
1. Filter type Electro
2. Number of fields 4
3. Capacity 450,000 m
3
/h
4. Ventilator type Radial (M-02-01)
5. Ventilator capacity 430,000 m
3
/h
Emitter (measuring point 2)
1. Emitter height 50.9 m
2. Diameter 3.2 m
© Svetlana Pavić. Reproduced by permission of Svetlana Pavić. Permission to reuse must be
obtained from the rightsholder.
ENERGY SOURCES, PART A: RECOVERY, UTILIZATION, AND ENVIRONMENTAL EFFECTS 489
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
ISO 9096:2003. The coal sampling point is not shown because the standard measuring point and
procedure regularly conducted in the cement factory were used.
4. Results and discussion
During monitoring of nitrogen and sulfur oxides emission from the cement kiln, coal and petroleum
coke were used as primary fuel, and whole or shredded tires as secondary fuel. Lower heating value
of coal was 26.5 MJ/kg and 31.9 MJ/kg for petroleum coke, while its value for scrap tires was around
27 MJ/kg. Coal and petroleum coke consumption varied depending on the heat ratio of scrap tires.
With the increase of heat ratio of tires, proportionally decreased the required amount of coal and
petroleum coke.
Relevant parameters, depending on the heat ratio of scrap tires, are shown in Table 4 and
Figure 2, as well as concentrations and mass flows of nitrogen and sulfur oxides measured after
bag filter (MP1), i.e., electrofilter of raw material drier (MP2) of cement production rotary kiln.
According to Ali et al. (2011), in the cement industry the typical values for NOx concentration is
<2003,000 mg/Nm
3
and for SO
2
concentration is <103,500 mg/Nm
3
.
A cement production rotary kiln, as well as devices for reducing emissions, were not specifically
prepared for the research, i.e., they were in the usual operating mode. The choice of plant load was
done so that it could realistically reflect the actual state of nitrogen and sulfur oxides emission.
During experimental research, it was observed that nitrogen and sulfur oxides emissions from the
cement production kiln mostly depends on the composition of raw material mixture; also, it depends
to a considerable extent on the composition of the fuel, and almost does not depend on the fuel
dosage method.
Table 4. Relevant parameters values for MP1 and MP2, depending on the heat ratio of scrap tires.
Measured Quantity Unit Measured Value
Heat ratio of scrap tires % 0.0 3.3 6.0 9.9 15.3
MP1 Volume fraction of O
2
% 11.88 12.53 11.60 11.65 11.92
Volume fraction of CO
2
% 14.64 12.72 14.89 14.04 13.84
Gases volume flow m
3
/h 438,773 436,938 427,450 429,923 446,205
Gas temperature °C 140 166 140 146 140
MP2 Volume fraction of O
2
% 12.11 12.30 12.66 12.81 12.74
Volume fraction of CO
2
% 13.88 12.83 12.93 12.07 12.67
Gases volume flow m
3
/h 235,016 202,880 253,222 240,725 236,352
Gas temperature °C 89.5 87.9 89.3 89.7 88.6
Figure 2. Influence of heat ratio of scrap tires on the concentration (a) and mass flow (b) of nitrogen and sulfur oxides.
490 B. NAKOMCIC-SMARAGDAKIS ET AL.
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
Experimental studies have shown that nitrogen oxides form during fuel combustion (coal,
petroleum coke, scrap tires) partially as a consequence of reaction of oxygen and nitrogen in the
air at high temperatures in a rotary kiln, and partially as a result of oxidation of nitrogen compounds
in the fuel. Amount of formed NOx is influenced by several factors, such as temperature of
combustion, flow velocity in combustion space, combustion space design, burner design, fuel
composition, ratio of fuel and air dosage, heat removal rate from combustion space, etc. (Dvořák
et al., 2010). During experimental tests, content of secondary fuels (scrap tires) was increased, and
primary fuels (coal, petroleum coke) were decreased, while other process parameters have not been
changed significantly. Thus, nitrogen oxides emission from a cement production kiln depended on
the content of nitrogen compounds in the used fuel. Since the nitrogen content in scrap tires is lower
than in coal and petroleum coke, the assumption is that nitrogen oxides emission is primarily
influenced by the quantity of scrap tires in the fuel mixture. Although with the increase of tiresshare
in total fuel quantity, at some point there is a reduction of NOx emissions; it cannot be concluded
that there is a direct dependence, because with 1015% of tires content NOx emissions is increasing
but still it stays below law-imposed limits.
Experimental studies also show that during the cement clinker production process release of
sulfur dioxide (SO
2
) depends on sulfur content in organic substance and pyrite present in the raw
material mixture, while scrap tires share in fuel mixture and fuel dosage method (primary or
secondary) had no significant impact on SO
2
emission. SO
2
emission did not significantly depend
on the used fuel type, because during experimental studies the difference between primary and
secondary fuel sulfur content was almost negligible. Raw material mixture content had the greatest
impact on SO
2
concentration in flue gases. However, after conducted research there could not be
defined a specific dependence between raw material mixture content and SO
2
emission from cement
production kiln. For further study of this dependence, there is a need to monitor SO
2
emission from
the rotary kiln for different sulfur content in raw material mixture, with other process parameters
unchanged.
In the literature exists different results for NOx and SO
2
emissions from the cement industry.
Prisciandaro et al. (2003) analyzed the emissions from an Italian cement plant using petroleum coke
and less than 20% tires. Through statistical analysis, the study asserted that, as compared with using
100% petroleum coke, the combustion of tires with petroleum coke in cement kilns increases SO
2
and NOx emissions. The study found that the increase of NOx emissions could be linked to the
burning conditions of the kiln, and in particular to excess air. Increased emissions of SO
2
are
supposedly caused by the incomplete combustion of tires, even though the amount of sulfur in the
mix of petroleum coke and tires is lower than for petroleum coke alone.
Carrasco et al. (2002) studied a Canadian cement factory that used coal as well as a combination
of coal and scrap tires. That study found a decrease in NOx emissions but an increase in SO
2
and
particulate emissions. They did not cite the percentage of scrap tires used as fuel; however, they
mentioned that the combustion efficiency was one of the main causes of pollutant emissions.
The UK Environment Agency (2008) conducted a study on a cement manufacturing plant in
Dunbar (using 25% tires), which showed an impact reduction, calculated through an environmental
quotient, for NOx. For SO
2
and particulate emissions, the situation was uncertain and case specific,
as findings showed both increases and decreases. The report suggested that this was due to the
pyritic sulfur content of raw materials, which has a substantial influence on emissions. The report
also cited the same behavior in four other UK cement factories.
A U.S. Environmental Protection Agency report (2006) stated that NOx emissions depend mainly
on the combustion process, while SO
2
emissions depend on the sulfur content of the fuel. The report
found that, although the use of tire-derived fuel did not decrease NOx emissions, it did not provide
further explanation about the methodology of the research. Another U.S. Environmental Protection
Agency report (2008), however, found that the use of scrap tires in cement kilns decreases NOx
emissions.
ENERGY SOURCES, PART A: RECOVERY, UTILIZATION, AND ENVIRONMENTAL EFFECTS 491
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
An International Energy Agency report (2009) stated that burning tire-derived fuel in cement
kilns, instead of fossil fuels, decreased both NOx and SO
2
emissions but the report did not provide
additional insights into this finding.
A LaFarge document (2003) contained a case study about the use of scrap tires in cement kilns. In
that case, a cement plant in Atlanta that used 20% scrap tires as fuel decreased NOx emissions
by 4.6%.
Two Portland Cement Association reports (2008,2009) found that nitrogen oxide, sulfur oxide,
and particulate emissions were lower when scrap tires substituted a portion of the fossil fuels. They
also found no statistically significant differences in those emissions.
5. Conclusions
Characteristics of the cement production process presented in this article show that this is an
environmentally acceptable way of disposing of scrap tires, either whole, shredded, or granulated.
Besides the fact that use of scrap tires as an alternative fuel in the cement industry is environmentally
friendly, it is also energy and economically justified.
Dry method technology of clinker roasting in a rotary kiln with a multilevel preheater and
precalcinator is the best available technique in cement production.
Nitrogen and sulfur oxide emissions measurement was carried out for different shares of scrap
tires in fuel, and it was done after the bag filter, as well as after the electrofilter of raw material drier
of cement production kiln. The measurements have shown that the nitrogen oxides emissions are
higher at the chimney after electrofilter of a raw material drier, and that sulfur oxides emissions are
higher at the kiln chimney after the bag filter. The mass flow of nitrogen oxides and sulfur is higher
through the kiln chimney after the bag filter, than through the chimney after electrofilter of raw
material drier.
According to the experimental results, influence of heat ratio of scrap tires on the concentration
and mass flow of nitrogen and sulfur oxides have shown that NOx and SO
2
emissions were in the
case of tires slightly decreased, in some cases were incremented, but remaining always below the
local law imposed limits and it is in accordance with the European Waste Incineration Directive and
the Integrated Pollution Prevention and Control Directive.
Differing results exist for SO
2
and NOx emissions when partial replacement of primary fuel with
scrap tires in the cement industry is in place, suggesting that the issues are case specific and it has to
be further researched.
Funding
This article is partly financed within III-46009, III-42004, III-42006, and No. 69-00-102/210-02 Projects of the
Ministry of Education and Science of Republic of Serbia.
References
Albino, V., Dangelico, R. M., Natalicchio, A., and Yazan, D. M. 2011. Alternative energy sources in cement manu-
facturingA systematic review of the body of knowledge. Department of Mechanical and Management Engineering,
Politecnico di Bari, Italy.
Ali, M. B., Saidur, R., and Hossain, M. S. 2011. A review on emission analysis in cement industries. Renewable
Sustainable Energy Rev. 15:22522261.
Bhatty, J. I. 1995. Role of minor elements in cement manufacture and use. Research and development bulletin RD109T.
Skokie, IL: Portland Cement Association.
Carrasco, F., Bredin, N., and Heitz, M. 2002. Gaseous contaminant emissions as affected by burning scrap tires in
cement manufacturing. J. Environ. Qual. 31:14841490.
Djekic, P., Temeljkovski, D., and Stojance, N. 2010. Selection of an optimal process for scrap tires recycling. Research
Des. Ind. 8:6572 (in Serbian).
492 B. NAKOMCIC-SMARAGDAKIS ET AL.
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
Dvořák, R., Chlápek, P., Jecha, D., Puchýř, R., and Stehlík, P. 2010. New approach to common removal of dioxins and
NOx as a contribution to environmental protection. J. Cleaner Prod. 18:881888.
ETRA. 2013. European Tire Recycling Association. Available at: http://www.etra-eu.org/.
International Energy Agency. 2009. Cement Technology Roadmap 2009. Available at: https://www.iea.org/publications/
freepublications/publication/Cement.pdf.
Jankovic, A., Valery, W., and Davis, E. 2004. Cement grinding optimisation. Min. Eng. 17:10751081.
LaFarge. 2003. LaFarge and the Environment 2003. Available at: http://www.lafarge.com/sites/default/files/import/
publication/09212004-publication_sustainability-Environment_brochure_2003-uk.pdf.
Lamas, W. Q., Palau, J. C. F., and Camargo, J. R. 2013. Waste materials co-processing in cement industry: Ecological
efficiency of waste reuse. Renewable Sustainable Energy Rev. 19:200207
Madlool, N. A., Saidur, R., Hossain, M. S., and Rahim, N. A. 2011. A critical review on energy use and savings in the
cement industries. Renewable Sustainable Energy Rev. 15:20422060.
Madlool, N. A., Saidur, R., Rahim, N. A., and Kamalisarvestani, M. 2013. An overview of energy savings measures for
cement industries. Renewable Sustainable Energy Rev. 19:1829.
Mokrzycki, E., and Uliasz-Bocheńczyk, A. 2003. Alternative fuels for the cement industry. Appl. Energy 74:95100.
Mokrzycki, E., Uliasz-Bocheńczyk, A., and Sarna, M. 2003. Use of alternative fuels in the Polish cement industry. Appl.
Energy 74:101111.
Nakajima, Y., and Matsuyuki, M. 1981. Utilization of waste tires as fuel for cement production. Conserv. Recycl. 4:145
152.
Nielsen, A. R. 2012. Combustion of large solid fuels in cement rotary kilns. Ph.D. Thesis, Department of Chemical and
Biochemical Engineering Technical University of Denmark, Kongens Lyngby, Denmark.
Oggioni, G., Riccardi, R., and Toninelli, R. 2011. Eco-efficiency of the world cement industry: A data envelopment
analysis. Energy Pol. 39:28422854.
Pavić, S. 2011. Comparative analysis of the flue gases composition during the transition from fossil to alternative fuels
in Lafarge Beocin cement factory. MSc Thesis, University of Novi Sad, Faculty of Technical Sciences. Novi Sad,
Serbia. [in Serbian]
Pipilikaki, P., Katsioti, M., Papageorgiou, D., Fragoulis, D., and Chaniotakis, E. 2005. Use of tire derived fuel in clinker
burning. Cement Concrete Compos. 27:843847.
Prisciandaro, M., Mazziotti, G., and Veglió, F. 2003. Effect of burning supplementary waste fuels on the pollutant
emissions by cement plants: A statistical analysis of process data. Resourc. Conserv. Recycl. 39:161184.
Portland Cement Association. 2008. Tire-derived Fuels. Available at: http://cement.org/Briefingkit/pdf_files/
TDFBrochure.pdf.
Portland Cement Association. 2009. Report On Sustainable Manufacturing. Available at: http://cement.org/smre
port09/images/shared_images/sustainreport08.pdf.
UK Environment Agency. 2008. The Use of Substitute Fuels in the UK Cement and Lime Industry. Available at: https://
www.gov.uk/government/uploads/system/uploads/attachment_data/file/291698/scho1207bnna-e-e.pdf.
U.S. Environmental Protection Agency. 2006. Controlling Fine Particulate Matter Under the Clean Air Act: A Menu of
Options. Available at: http://www.4cleanair.org/PM25Menu-Final.pdf.
U.S. Environmental Protection Agency. 2008. Trends in Beneficial Use of Alternative Fuels and Raw Materials
Cement Sector. Available at: http://archive.epa.gov/sectors/web/pdf/cement-sector-report.pdf.
Zabaniotou, A., Lagoudakis, J., Toumanidou, E., and Stavropoulos, G. 2002. Energetic utilization of used tires. Energy
Sources Part A 24:843854.
ENERGY SOURCES, PART A: RECOVERY, UTILIZATION, AND ENVIRONMENTAL EFFECTS 493
Downloaded by [Zoran Cepic] at 01:04 10 February 2016
... Of the 280 million used tires in the UK, more than 100 million tires are used as fuel, and most of these are burnt to supplement fuel in cement and other rotary kiln operations (Boateng, 2016). The use of tires as a raw material in kilns provides 112 million GJ of energy for the technology, where the waste disposal and energy recovery take place at the same time (Nakomcic-Smaragdakis et al., 2016), which is a costeffective technology for replacing fossil fuels. The steel belts in tires may be used to replace a portion of the iron required in the raw materials. ...
Article
Full-text available
Consumer society requires the continuous evolution of products, thus generating a lot of waste. The automotive industry has also undergone significant development, generating 1.5 billion used tires worldwide every year. Landfilling of tires is prohibited and their disposal is therefore a major issue. Although many studies deal with the utilization of tire as a fuel, there is limited research that would specifically describe the relationship between pollutant emissions from tire combustion and the relationship between emitted pollutants and firebox temperature. Based on this, this work aims to investigate flue gas concentrations (CO, CO2, NOx, and SO2) and solid pollutants from tire burned in a lab-scale electrical furnace at firebox temperature from 650 to 900 °C. The decomposition of the CaCO3 filler during the combustion of the tire has been detected with thermal analytical investigation and combustion experiments. In the case of the CO flue gas pollutant, a second maximum concentration is observed due to the presence of CaCO3. With the increasing firebox temperature, the size of solid particles decreases, and the mesh structure formed becomes denser. At the same time, the concentration of emitted solid PAHs decreases, dominated by aromatic compounds with smaller number of rings. However, the variation of firebox temperature does not affect the amount of benzo(b)fluoranthene and fluoranthene relative to the total concentration.
... Previous studies have shown that it is feasible to replace existing fuels with waste tires. The calorific value of waste tires in cement kilns is 270 MJ·kg −1 , which is 26.5 MJ·kg −1 higher than existing fuels such as coal [36]. In the previous studies, it was found that only 20 lb of shredded waste rubber tires can replace 25 lb of coal [37]. ...
Article
Full-text available
In the construction industry, fibers have been added to concrete to improve the mechanical properties of concrete for decades. Steel fiber has been widely used as an additive fiber owing to the unique properties; it provides reinforced concrete. However, the large-scale production of steel fibers generates a large amount of CO2 and aggravates the depletion of natural resources. In response to the requirements of green environmental protection, some scholars have focused their attention on replacing industrial steel fibers with recycled steel fibers from waste tires (WTSF). It is found that WTSF can be used to reinforce the mechanical properties of concrete and even replace industrial steel fiber (ISF) in some engineering applications. The existing research results are summarized and discussed, with emphasis on the process of recycling WTSFs. This review not only has a great impact on the environment but also has fiber characteristics as well as the mechanical properties (compressive strength, tensile strength, and flexural strength) and durability of the concrete with WTSF. The purpose of this article is to review the existing literature with a critical attitude and summarize the existing related literature, which determines the research gap for those who are committed to this direction.
... Therefore, considering the high environmental impacts and GHG emissions potential of both cement and construction industries, it is essential to take steps and develop mitigation strategies to control and reduce CO 2 emissions in the sector. In the past few years, several mitigation strategies have been implemented to reduce the negative impact of the construction industry on climate change, in general, which are (1) increasing energy efficiency in both cement and construction industries; and (2) using alternative fuels (e.g., biofuels, municipal wastes, scrap tiers [92] in cement kiln); clinker substitution/blended cement; reuse of C&D waste using circular economy concept [93]. ...
Article
Full-text available
Conventionally, in a linear economy, C&D (Construction and Demolition) waste was considered as zero value materials, and, as a result of that, most C&D waste materials ended up in landfills. In recent years, with the increase in the awareness around sustainability and resource management, various countries have started to explore new models to minimize the use of limited resources which are currently overused, mismanaged, or quickly depleting. In this regard, the implementation of CE (Circular Economy) has emerged as a potential model to minimize the negative impact of C&D wastes on the environment. However, there are some challenges hindering a full transition to CE in the construction and demolition sectors. Therefore, this review paper aims to critically scrutinize different aspects of C&D waste and how CE can be integrated into construction projects. Reviewing of the literature revealed that the barriers in the implementation of CE in C&D waste sectors fall in five main domains, namely legal, technical, social, behavioral, and economic aspects. In this context, it was found that policy and governance, permits and specifications, technological limitation, quality and performance, knowledge and information, and, finally, the costs associated with the implementation of CE model at the early stage are the main barriers. In addition to these, from the contractors’ perspective, C&D waste dismantling, segregation, and on-site sorting, transportation, and local recovery processes are the main challenges at the start point for small-scale companies. To address the abovementioned challenges, and also to minimize the ambiguity of resulting outcomes by implementing CE in C&D waste sectors, there is an urgent need to introduce a global framework and a practicable pathway to allow companies to implement such models, regardless of their scale and location. Additionally, in this paper, recommendations on the direction for areas of future studies for a reduction in the environmental impacts have been provided. To structure an effective model approach, the future direction should be more focused on dismantling practices, hazardous material handling, quality control on waste acceptance, and material recovery processes, as well as a incentivization mechanism to promote ecological, economic, and social benefits of the CE for C&D sectors.
Article
This work investigates the combustion analysis of coal, petroleum coke and their blends. Coal and petroleum coke were characterized by proximate analysis, ultimate analysis, gross calorific value determination and ash analysis. Combustion performance of parent fuels and their blends were evaluated by thermogravimetric analysis followed by the analysis of different characteristics parameters, namely ignition temperature, peak temperature, burnout temperature and combustion efficiency. Results signify that petroleum coke has poor combustion characteristics compared to coal. After the rise in petroleum coke from 10 to 50 mass %, ignition temperature reduced from 413 to 385 °C, while insignificant variations occurred in peak temperature and burnout temperature. Such observations show natural reduction in ignition characteristics without significant modification in coal's burning profile. Combustion efficiency at 450 °C reduced from 46.18 to 34.77 % as petroleum coke increased from 10 to 50 mass %, signifying decline in the combustion properties of coal. Kinetic analysis shows that petroleum coke has the maximum activation energy (182.11 kJ/mol) than coal (84.84 kJ/mol). Analysis of changes in enthalpy, Gibbs free energy and entropy inferred that individual combustion of both coal and petroleum coke is difficult, while blends have improved combustion characteristics than petroleum coke.
Article
Full-text available
In this paper, low-temperature extrusion of ground tire rubber was performed as a pro-ecological waste tires recycling method. During this process, ground tire rubber was modified with constant content of dicumyl peroxide and a variable amount of elastomer (in the range: 2.5–15 phr). During the studies, three types of elastomers were used: styrene-butadiene rubber, styrene-ethylene/butylene-styrene grafted with maleic anhydride and ethylene-octene copolymer. Energy consumption measurements, curing characteristics, physico-mechanical properties and volatile organic compounds emitted from modified reclaimed GTR were determined. The VOCs emission profile was investigated using a passive sampling technique, miniature emission chambers system and static headspace analysis and subsequently quantitative or qualitative analysis by gas chromatography. The VOCs analysis showed that in the studied conditions the most emitted volatile compounds are dicumyl peroxide decomposition by-products, such as: α-methylstyrene, acetophenone, α-cumyl alcohol, methyl cumyl ether, while the detection level of benzothiazole (devulcanization “marker”) was very low. Moreover, it was found that the mechanical properties of the obtained materials significantly improved with a higher content of styrene-butadiene rubber and styrene-ethylene/butylene-styrene grafted with maleic anhydride while the opposite trend was observed for ethylene-octene copolymer content.
Article
Full-text available
Alternative fuels (AFs) have a number of benefits in the cement industry, including lower greenhouse gas emissions and reduced use of non– renewable fossil fuels are replaced with materials that would otherwise be degraded or incinerated, leading to emissions and final residues. As a result, identifying the most significant environmental impacts involved with clinker processing, and using the best available production techniques are essential for environmental sustainability. The life cycle evaluation of clinker production using traditional fuels (tire derived fuel) was also developed, as well as a comparative life cycle assessment (LCA) analysis also developed.
Article
Full-text available
In this study, we conducted full life-cycle studies on pollutants in a cement plant co-processing hazardous waste (HW) via the combined use of thermodynamic equilibrium calculations and the American Meteorological Society/Environmental Protection Regulatory Model.
Chapter
Generally, fly ash (FA) and bottom ash (BA) are produced by the process of combustion in coal-fired power plants that considered as waste which includes heavy metals in its composition. Moreover, these metals are harmful to both the atmosphere and human health. Apparently, for these ashes, treatment methods are available, and one of them is the replacement of FA and BA as concrete materials. Therefore, the primary purposed of this paper was to investigate the properties and characteristics of self-compacted concrete (SCC) incorporated with fly ash and bottom ash. SCC was developed with different percentages of FA and BA as a replacement for cement and sand with ratios of 10, 20 and 30% respectively. The properties tested were slump flow and t500 test, sieve segregation, and J-ring test for physical characteristic. Next, density, compressive power, and water absorption were examined to determine its mechanical characteristic. The results revealed that both physical and mechanical characteristics with 20% of FA and BA in SCC were suitable to be defined as SCC. A comparable set of data in compressive strength were observed, and densities have been established as standard weight concrete. In conclusion, this research demonstrates that FA and BA material are possibly be used as a new material for concrete production.
Chapter
Researchers are trying to find a suitable method to treat petroleum sludge (PS) waste and they proposed different methods. In this study, PS was characterized to understand their suitability to be treated in cement plants. Therefore, PS was analyzed for their physical, chemical and gas emission properties. The results revealed that PS is a hazardous waste that could pose serious problems to the environment and living things if it is disposed of in the environment without treatment. In addition, the treatment of PS is limited to incineration method in closed space in order to ensure the complete burning of this waste, which could be executed within the cement kiln. Thus, one of the alternative methods is to treat PS within the cement production plants, which may provide the advantages of using this waste as ingredient to decrease the consumption of raw materials and fuel within the cement plants.
Article
This paper is based on the latest data from the field of processing and recycling of waste tires. The paper explained most common methods of recycling in world and in our contry. We have analyzed the processes of milling and process waste tires pirolize. U paper presents data on the possibility of applying the product obtained by recycling process. Method weights were analyzed recycling process and was chosen the most optimal method of recycling. Evaluation was conducted based on multiple criteria, and all the perceived advantages and disadvantages of the given processing waste tires, that would eventually come to the process of "pyrolysis". At the end of the listed advantages of the most optimal process compared to other methods.
Article
Due the advances in the industrial processes, in which the cement industry is a major contributor, energy consumption and greenhouse gas emission has increased significantly. This paper reviews previous studies on energy saving, carbon dioxide emission reductions and the various technologies used to improve the energy efficiency in the cement industry. Energy efficiency measures for raw materials preparation, clinker production, products and feedstock changes, general energy efficiency measures, and finish grinding have been surveyed. It was found that the largest recorded amounts of thermal energy savings, electrical energy savings and emission reductions to date are 3.4 GJ/t, 35 kW h/t and 212.54 kgCO(2)/t, respectively.
Article
The prerequisites for using of tire derived fuel (TDF) as a supplement fuel for the clinker production are stated. Measurements were carried out by using different qualitative analytical techniques such as, X-ray diffraction (XRD), X-ray fluorescence (XRF), optical microscopy in two series of raw mill, clinker and fuel samples with and without the use of TDF. Furthermore, the compressive strength of CEM I-52.5 cement produced was measured. In this specific study 6% of the total fuel used was TDF. It was concluded that no apparent problems occurred from the use of TDF as a supplemental fuel in the clinker burning.
Article
The current world consumption of cement is about 1.5 billion tonnes per annum and it is increasing at about 1% per annum. The electrical energy consumed in cement production is approximately 110kWh/tonne, and around 40% of this energy is consumed for clinker grinding. There is potential to optimise conventional cement clinker grinding circuits and in the last decade significant progress has been achieved. The increasing demand for “finer cement” products, and the need for reduction in energy consumption and green house gas emissions, reinforces the need for grinding optimisation.This paper describes the tools available for the analysis and optimisation of cement grinding circuits. The application of the Bond based methodology as well as Population Balance Models (PBM) is presented using a case study. The throughput of current conventional closed grinding circuit can be increased by 10–20% by pre-crushing the clinker using the Barmac crusher. A potential for application of stirred milling technology for fine cement grinding was also discussed.
Article
Meeting environmental limits represents the most important issue in the field of waste processing. Our primary effort consists either in eliminating hazardous emissions or in prevention of their production. However, this is not feasible in most cases therefore the so called secondary methods have to be applied. Technologies based on adsorption of hazardous compounds using activated carbon, deNOx/deDiox technologies as well as technology of catalytic filtration using a special material REMEDIA® proved itself to be very efficient. The latter technology consists in using a baghouse with bags manufactured from a special material (two layers – membrane from ePTFE and felt with bound in catalyst) called REMEDIA® which has successfully been used for removal of PCDD/F during recent period. However, it has been found that this technology can partially remove NOx as well. Based on our experience from operation industrial incineration plants it has been proved that even after more than three years' operation the activity of filtration material was not decreased and efficiency of dioxins removal from flue gas ranges from 97 to 99% (Pařízek et al., 2008).
Article
The cement subsector consumes approximately 12-15% of the total industrial energy use. Therefore, this subsector releases CO 2 emissions to the atmosphere as a result of burning fossil fuels to produce energy needed for the cement manufacturing process. The cement industry contributes about 7% of the total worldwide CO 2 emissions. This study complied a comprehensive literature in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites for emission generation and mitigation technique. Emission released associated with the burning of fuels have been presented in this paper. Different sources of emissions in a cement industry has been identified and presented in this study. Different techniques to reduce CO 2 emissions from the cement manufacturing industries are reviewed and presented in this paper. The major techniques are: capture and storage CO 2 emissions, reducing clinker/cement ratio by replacing clinker with different of additives and using alternative fuels instead of fossil fuels. Apart from these techniques, various energy savings measures in cement industries expected to reduce indirect emissions released to the atmosphere. Based on review results it was found that sizeable amount of emission can be mitigated using different techniques and energy savings measures.
Article
The cement sub-sector consumes approximately 12-15% of total industrial energy use. Therefore, a state of art review on the energy use and savings is necessary to identify energy wastage so that necessary measures could be implemented to reduce energy consumption in this sub-sector. In this paper energy use at different sections of cement industries, specific energy consumption, types of energy use, details of cement manufacturing processes, various energy savings measures were reviewed and presented. Various energy savings measures were critically analyzed considering amount of energy that can be saved along with the implementation cost. Amount of CO(2) reduction has been presented along with the payback period for different energy savings measures as well. This study complied a comprehensive literature on the cement industries in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites. It has been observed that China producing major share of global cement production. Coal contribute major share of fuel used in cement industries. However, along with conventional fuels, industries are moving towards the use of alternative fuels to reduce environmental pollution. It was reported that cement industries are moving from wet process to dry process as it consume less energy compared to wet process.
Article
In this study, used tire pyrolysis experiments were performed in a captive sample reactor, at atmospheric pressure, under a helium atmosphere. The effects of temperature on the yields and composition of the pyrolysis products were investigated. Char yield decreased with the temperature of pyrolysis, while total gas yield increased. Tar and liquid hydrocarbons increased slightly with temperature. Experiments combined with a first-order kinetic model allowed the estimation of the kinetic parameters for total weight loss. The char produced by pyrolysis was burned and its reactivity was measured as a function of pyrolysis temperature. It was found that there was a decline in reactivity for charring temperatures above 650°C and that char produced at low pyrolysis temperature is preferable for medium heating value solid fuel uses.