E. Fidancevska,
V. Vassilev,
M. Milosevski,
S. Parvanov,
D. Milosevski,
Aljihmani
Journal
of the University
of Chemical
Technology
and Metallurgy,
42, 3, L.
2007,
285-290
COMPOSITES BASED ON INDUSTRIAL WASTES
III. PRODUCTION OF COMPOSITES OF Fe-Ni SLAG AND WASTE GLASS
E. Fidancevska1, V. Vassilev2, M. Milosevski1, S. Parvanov2, D. Milosevski1, L. Aljihmani2
1
Faculty of Technology and Metallurgy, Rudjer Boskovic
16, Skopje, R. Macedonia
2
University of Chemical Technology and Metallurgy
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: venciv@uctm.edu
Received 05 April 2007
Accepted 12 July 2007
ABSTRACT
Composites are produced from industrial wastes: ferro-nickel slag (slag of the “refining” and “melting” processes)
and waste glass (TV monitor glasses, window and containers glasses). The composites are characterized from the view
point of: glass concentration, sintering temperature, structure, density, porosity, elasticity modulus, bending strength,
relative thermal expansion and temperature coefficient of linear expansion. An optimal combination for porosity, thermodynamical stability and mechanical characteristics (high density and elasticity modulus at low technical coefficient of
thermal linear expansion) in the temperature range 20-600 oC, shows the composite (Slag-M + 20 % TV glass), sintered at
1150 oC/2h. The composite chemical resistance is examined in acid and alkaline media.
Keywords: metallurgical slag, waste glass, utilization of slag and waste glasses, composite mechanical and thermal
properties.
INTRODUCTION
The wastes of industry and households contain
high concentrations of toxic substances, heavy metals,
organic substances and soluble salts [1]. Currently, in
order to prevent the environment contamination by toxic
elements, recycling and encapsulation of the chemical
wastes [2], which are expensive industrial processes [3]
are carried out. That calls for the continuous development of new methods and technologies which require
minimum quantity of energy and time. One of the modern trends is to transform the environmentally detrimental components in inert products, e.g. by the technologies of melting and atomization that encapsulate
the heavy metals while the organic substances completely
decompose. The glass phase which is a component part
of many waste materials plays the role of an encapsulating coating. By mixing the glass with the environmentally detrimental substances and subsequent heat
treatment, products of multi-barrier structures are produced [4]: the crystalline materials in them transform
in a new product and the glass fixes (encapsulates) the
toxic substances or stimulates their decomposition. A
typical example of application of this technology is the
eco-cement developed from metallurgical slag which
does not contain heavy metals [5]. The detoxication is
performed by melting the slag in an electric furnace at
temperature between 1300 - 1500°C. During the ,,melting” process the heavy metals and the non-organic components of the slag are „frozen” in the glass matrix as a
result of which a stable product is obtained that is not
toxic for the environment [6]. The present series of papers concerning utilization of industrial wastes does not
consider the methods and technologies for secondary
extraction of certain metals and chemical compounds
from them [7, 8].
In many parts of Europe the waste window glass
( ≈ 26 %) is recycled and returned for second melting
285
Journal of the University of Chemical Technology and Metallurgy, 42, 3, 2007
[9]. The container glass is recycled as a raw material
and the percent of recycling varies in dependence of the
color: 82 % - for green, 44.5 % - for brown and 43.8 %
for the white glass [10]. From an ecological point of
view window and container glasses are harmless and
can be used as an initial material for blocking the detrimental and dangerous elements in the environment. The
TV monitor glass (TV-glass) contains Pb, Sb, Sr, etc.
and could be detrimental for the environment. The TVglass of the television sets and computer monitors may
also contain heavy metals in its composition in the form
of Fe, Ni, Co, Cu, Mn, V, Ce, etc. oxides. Generally, the
glass is an excellent material for bonding the heavy metal
oxides. They bond with the SiO2 of the glass matrix
which retains them inside the matrix and decreases their
solubility in acid media [11].
With the purpose to protect the environment,
metallurgical and glass wastes (slag, powders, containers, window and TV-glasses as well as others) can be
used as initial raw materials for the manifacture of new
materials useful for other products, as shown in details
in our previous publications [12, 13] that describe individually a number of possibilities for application of
metallurgical slag and waste glass most of all in the
form of components in various composites.
A particular interest presents the simultaneous
utilization of these wastes in the form of composites
with possibilities for various applications. This concept
already finds real confirmation in the publications of
many authors. For instance, methods and technologies
for production of compact and porous glass-ceramic
materials [16] from metallurgical and glass wastes [14 15] at controlled heat treatment are proposed. These
materials are used for the manufacture of electronic
components [46], optical sensors [18], additives for biomedical products [19], catalysts, membranes, sensors
[18], composite materials [20], etc.
The metallurgical slag the composition of which
is dominated by Si- and Al-oxides can be used as a raw
material for production of composites intended for ceramic filters, aerators and diffusers that can be applied
for purification of industrial gases and waste waters [21].
These composites show good chemical, physical, microbiological and mechanical properties as well as resistance to sharp temperature changes [15]. The presence of heavy metals in the slag, such as Sn, Sb, Cd, Ba,
As, Sr, Zn, Pb, Mo, is eliminated by the use of waste
286
glass which fixes them in the matrix of the composite
during the liquid phase synthesis [22].
The presented data does not exhaust all possible
options for utilization of the “stocks” of metallurgical
and glassy wastes (slags, glasses from containers, windows and TVs) but significantly shows that their application depends on their physico-chemical properties and
in the case of their “transformation” in composites –
on the properties of the composite itself.
The aim of the present investigation is obtaining of composites and after the “partial” properties of
the constructing waste components: metallurgical slag
[12] and glasses [13] are known – investigation of their
main physico-chemical characteristics and outlining
on their basis the possibilities for their concrete applications.
EXPERIMENTAL
The powder morphology was studied by scanning electron microscope CEM Leica S 440i at magnification of 50 - 2000 times.
The milling and mechanical activation of the raw
materials was performed with a planetary mill (Al2O3
balls); milling time: 1-3 hours; medium: alcohol+water.
A “Fritsch pulverisette 5” mill was used. For the first
stage of the sintering a uniaxial press (Weber Pressen
KIP 100) with 10 - 400 MPa pressure was used; the
matrices being in the shape of a parallelepiped and dimensions: a = 60 mm, b = c = 4 - 6 mm.
The mechanical tester Netzsch 401/3 was used for
determination of the elasticity modulus and the bending
strength. The samples of a parallelepiped shape are polished in advance with diamond paste (particle size 9 ìm).
The dilatometer Netzsch 402E was used for examination of the thermo mechanical and thermo cyclic
characteristics of the sintered samples in the range of
20 - 600 - 20oC such as: technical coefficient of thermal linear expansion, physical coefficient of thermal
linear expansion, temperature alternation of ÄL/L, as
well as thermodynamic stability of the sintered compact substances by analysis of the hysteresis effect. The
rate of sample heating/cooling was 2°C/min.
The density (real and theoretic) and the porosity of the samples from the different systems were defined by methods described in details in the literature
[12, 13].
E. Fidancevska, V. Vassilev, M. Milosevski, S. Parvanov, D. Milosevski, L. Aljihmani
RESULTS AND DISCUSSION
Table 1. Density, mechanical properties and porosity of the sintered composites (Slag-R + glass).
Metallurgical slag from Kavadarci
Slag-R
T, °C ó, MPa E, GPa ñr, g/cm3 ñth, g/cm3 È, %
(Macedonia) - slag of the process „refinSlag-R + 10% TV-glass
1100 43.5
33.1
3.20
4.80
33
ing” (Slag-R) and slag of the process
Slag-R + 10% TV-glass
1150 47.3
39.0
3.22
4.80
33
„melting” (Slag-M) and waste glass (from
Slag-R + 10% TV-glass
1200 49.8
40.4
3.29
4.80
31
TV monitors, windows and containers)
Slag-R + 20% TV-glass
1100 45.0
37.6
3.33
4.55
27
have been used as initial components for
Slag-R + 20% TV-glass
1150 49.2
42.2
3.60
4.55
21
Slag-R
+
20%
TV-glass
1200
52.1
42.4
3.63
4.55
20
production of the composites. The chemiSlag-R
+
10%
window
glass
1100
42.4
32.9
3.10
4.80
35
cal composition of the Fe-Ni slag shows
Slag-R + 10% window glass 1150 44.1
37.8
3.20
4.80
33
that they are multi-component silicate
Slag-R + 10% window glass 1200 49.3
39.8
3.45
4.80
28
systems of high Fe2O3, FeO, SiO2, CaO
Slag-R + 20% window glass 1100 43.2
34.2
3.13
4.56
31
and MgO content [12]. The chemical Slag-R + 20% window glass 1150 45.3
40.6
3.36
4.56
26
analysis of the TV-glass shows high con- Slag-R + 20% window glass 1200 50.6
41.5
3.61
4.56
21
tent of the ecologically dangerous lead
oxide (PbO=8.18 %) [13]. Before usage,
Table 2. Density, mechanical properties and porosity of sintered at 1000°C
the window and container glasses undergo
composites from Slag-M + glass and Slag-R + glass depending on the
fragmentation and milling. The monitor
type of the slag and the waste glass and also from the percentage of glass.
glass is treated in advance by 12 % solution of HF in order to remove the chemiSlag-M
ó, MPa E, GPa ñ, g/cm3 ñthe,.g/cm3 È, %
cal inclusions accompanying every TV
FE-NI + 10% TV glass
28,40 16,70
2,37
3,59
34
screen [23].
FE-NI + 20% TV glass
35,37 17,05
2,36
3,48
32
The basic physico-chemical propFE-NI
+
30%
TV
glass
43,73
18,40
2,34
3,37
31
erties of the ferro-nickel slag and the
FE-NI + 40% TV glass
59,96 27,53
2,31
3,26
29
waste glass used as initial components for
FE-NI + 50% TV glass
62,73 35,29
2,29
3,16
28
production of composite materials have
FE-NI + 10% window glass 14,15 6,82
2,26
3,60
37
been investigated in our previous work
FE-NI + 20% window glass 19,76 11,65
2,20
3,49
37
[12, 13].
FE-NI + 30% window glass 28,65 16,65
2,12
3,39
37
The composites made from the slag
FE-NI + 40% window glass 36,20 18,12
2,06
3,28
37
and waste glass have been produced by
FE-NI + 50% window glass 49,79 20,76
2.00
3,18
37
mechanical mixing of both components, FE-NI + 10% container glass 23,57 12,18
2,22
3,58
38
the content of the glass being in the range FE-NI + 20% container glass 28,31 15,28
2,14
3,47
38
from 10 to 50 mass. %. The mixing (ho- FE-NI + 30% container glass 29,27 16,26
2,13
3,35
36
mogenization), accompanied by parallel FE-NI + 40% container glass 35,32 17,03
2,12
3,24
35
mechanical activation has been performed in a planetary mill: moist
The composites (Slag-R + 10 or 20 % TV-glass),
(alcohol+water) media for 1 hour.
sintered at 1150 °C/2h, show significant deformation while
The composite aggregation was carried out by
the composites (Slag-R + 20 % window glass) deform at
uniaxial pressing with the use of plasticizer polyvinyl
1200°C/2h, which is a result of the lower melting point
alcohol (PVA) and pressure of 30 ÌPa. The pressed
of the TV-glass compared to the window glass. The comsamples in the shape of a parallelepiped were sintered
posites (Slag-Ì + waste glass) show melting at sinterin a chamber furnace at T = 900 - 1200°C (in air meing temperatures of 1150°C/2h, when in their composidium) at heating rate of 10 °C/min and holding at the
tion participate the three types of waste glass in confinal temperature for 2 hours.
centrations 10, 20, 30, 40 or 50 %mass., respectively.
The bending strength (ó), elasticity modulus (E),
The analysis of the results, presented in Tables 2
density (real ñr and theoretic ñth) and the porosity (è) of
and
3,
shows
that the type and the percentage content of
some of the composites are shown in Tables 1 - 3.
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Journal of the University of Chemical Technology and Metallurgy, 42, 3, 2007
Table 3. Density, mechanical properties and porosity of the sintered composites
from Slag-M + 20 % waste glass depending on the sintering temperature.
itself, since it leads to densification of the
composites. This influences directly the
physico-chemical characteristics of the
Slag-M
T, °C ó, MPa E, GPa ñ, g/cm3 ñthe,.g/cm3 È, % composites: porosity, density, chemical
stability, hardness, strength, etc., as conFE-NI + 20% TV glass
1000 35,37 17,05
2,36
3,48
32
firmed by the results shown in Table 3.
FE-NI + 20% TV glass
1050 53,97 23,06
2,42
3,48
30
FE-NI + 20% TV glass
1100 57,05 40,10
2,75
3,48
21
From the analysis of Tables 1, 2
FE-NI + 20% TV glass
1150 64,82 47,95
3,34
3,48
4
and 3 a very significant for the practice
FE-NI + 20% window glass 1000 19,76 11,65
2,20
3,49
37
conclusion can be made: the properties
FE-NI + 20% window glass 1050 42,34 17,59
2,35
3,49
33
of the composites are in close relation
FE-NI + 20% window glass 1100 53,65 22,41
2,57
3,49
26
with the slag type, the kind and the conFE-NI + 20% window glass 1150 60,98 34,39
2,98
3,49
15
tent of the glass phase, as well as with
2,14
3,47
38
FE-NI + 20% container glass 1000 28,31 15,28
the sintering temperature. This obserFE-NI + 20% container glass 1050 48,73 20,43
2,34
3,47
33
vation allows for obtaining of composFE-NI + 20% container glass 1100 56,92 24,71
2,58
3,47
26
ite materials with pre-set properties
FE-NI + 20% container glass 1150 77,41 39,93
2,92
3,47
16
from these wastes (slag and glass).
If as criteria for the selection of a composite the
the glass, as well as the sintering temperature have sigmechanical properties (ó and E), the density (ñr) and
nificant influence on the mechanical properties of the
the porosity (è) are taken, then the best qualities has
composites. The influence of these indices on the pothe composite (Slag-M + 20 % TV-glass), sintered at
rosity is more particular: the first two have a rather
1150°C/2h. It is characterized by porosity of 4 %, i.e.
weaker influence on it, while the third factor leads to
its density is 96 % of the theoretical one and at the
its considerable decrease (Table 3).
same time it shows also the best mechanical properties.
The metallurgical slag and the waste glasses from
Fig. 1 presents its microstructure.
a chemical point of view are multicomponent and enough
The dark sections in the Figure are slag particles
compositionally complicated systems. It is completely
and the light section is molten glass phase. In the light
logical that at the high-temperature sintering they pass
section there are white zones with size of 5 - 10 % of
through various chemical interactions such as: solid +
the diameter of the slag particles. They are a crystalsolid, solid + liquid and liquid + liquid, as a result of
lized glass phase. Therefore, we can draw the concluwhich low-melting eutectics and/or chemical comsion that the slag grains are surrounded by molten parpounds are formed. This can lead to melting of the comtially crystallized glass phase.
posite at the sintering temperature (observed at comThe composites (Slag + glass) were subjected to
posites sintered at 1150oC, composed by Slag-M + 10
dilatometer measurements in 20 – 600 - 20°C cycle
(20, 30, 40 and 50 mass. %), while the obtained liquid
with the purpose to define their thermo cyclic characphase has a positive influence on the milling process
Table 4. Thermo-cyclic characteristics of the composites Slag + glass.
System
Slag-R + 20 % TV glass
Slag-R + 20 % window glass
Slag-M + 20 % TV glass
Slag-M + 20 % window glass
Slag-M + 20 % container glass
288
∆L/Lo = a+bT+cT 2 +dT 3
αph. = b+2cT+3dT 2
-0.213+0.012T-9.454 10-6 T 2 +1.412 10-8 T 3
α = 0.012 – 1.891 10 -7 T +4.236 10-8 T 2
-0.263+0.019T-2.420 10-5 T 2 +2.505 10-8 T 3
α = 0.019 – 4.840 10 -5 T +7.515 10-8 T 2
-0.221+0.014T-1.729 10-5 T 2 +1.820 10-8 T 3
α = 0.014 – 3.458 10 -5 T + 5.46 10-8 T 2
-0.178+0.011T+3.262 10-6 T 2 -5.174 10-9 T 3
α = 0.011 – 6.524 10 -6 T +1.552 10 -10 T 2
-0.450+0.025T+4.227 10-5 T 2 –3.584 10-8 T 3
α = 0.025 – 8.454 10 -5 T +1.075 10-9 T 2
αt, 10 -6 ,
o -1
C
10.9
11.8
11.1
11.5
11.4
E. Fidancevska, V. Vassilev, M. Milosevski, S. Parvanov, D. Milosevski, L. Aljihmani
=
>
Fig. 1. Microstructure of bulk composite (Slag-M + 20 % TVglass) (1:100).
Fig. 2. Specific thermal expansion curves at heating/cooling of
a composite Slag-M + 20 % TV-glass.
teristics as well as to test their thermodynamic stability.
In case the composite contains micro cracks that are
one of the main reasons for the effect of hysteresis then
we assume a thermodynamical instability of the composites. The dependence ∆L/L = f(T), the physical coefficient of thermal linear expansion and the technical
coefficient of thermal linear expansion (át) at 6 thermal cycles (20 → 600 → 20 °C) of the test are shown in
Table 4.
All examined composites (Slag-M + waste glass)
are thermodynamically stable (there is no effect of hysteresis), i.e. in the studied temperature range there are
no chemical, physical or structure changes. There are
no cracks in the samples whose presence might lead to
severe deterioration of the composite mechanical properties. The values of the physical and technical coefficients of thermal linear expansion are close to the additive value of the partial coefficients of thermal expansion calculated by the parts of the matrix (metallurgical
slag) and the disperse phase (waste glass). The thermo
Fig. 3. Solubility of Slag-M, waste glass and composites on their
base in 0.1mol/dm3 HCl (a) and in 0,1mol/dm3 Na2CO3 (b): 1 - SlagM; 2 - TV-glass; 3 - window glass; 4 - containers glass; 5 - Slag- M
+ 10 % TV-glass; 6 - Slag-M + 20 % TV-glass; 7 - Slag-M + 30 %
TV-glass; 8 - Slag-M + 40 % TV-glass; 9 - Slag-M + 10 % window
glass; 10 - Slag-M + 20 % window glass; 11 - Slag-M + 30 % window
glass; 12 - Slag-M + 40 % window glass; 13 - Slag-M + 10 %
containers glass; 14 - Slag-M + 20 % containers glass; 15 - Slag-M
+ 30 % containers glass; 16 - Slag-M + 40 % containers glass.
cycle curve of heating/cooling of the optimal composite Slag-M + 20 % TV-glass is presented in Fig. 2.
The solubility of the composites (Slag-M + glass)
and the components entering in its composition in 0,1
mol dm-3 HCl and 0,1 mol dm-3 Na2CO3 during 24 h,
168 h and 720 h provide information both for the chemical stability of the samples and for the degree of packing of the slag particles by the glass film. Fig. 3 presents
the obtained results.
CONCLUSIONS
• On the basis of chemical, geometrical, structural and thermo-physical considerations two of the
main environmental polluters are chosen – ferro-nickel
slag (slag of the refining process and slag of the melting
process) and waste glass (TV-monitor glass, window and
containers glasses).
• A method for obtaining of composites
(slag+glass) is developed – with glassy phase content
289
Journal of the University of Chemical Technology and Metallurgy, 42, 3, 2007
form 10 to 50 % at the following conditions: sintering
temperatures – 900 - 1200°C; medium – air; heating
rate - 10 °C/min, duration of the last temperature step –
2 hours. When varying the proportion of the slag and the
waste glass, as well as the sintering conditions, composites with porosity 4 - 42 %; density – 1.90 - 3.63 g cm-3;
bending strength – 7.20 - 77.41 MPa; and elasticity modulus – 4.28 - 47.95 GPa, are obtained;
• The composite (Slag-M + 20 % TV glass), sintered at 1150oC/2h, shows optimal combination between
the porosity, the thermodynamical stability and the mechanical characteristics (high density and elasticity modulus at low technical coefficient of thermal linear expansion) in the temperature range 20 – 600oC,.
• The chemical stability of the waste glasses, slag
and their composites is investigated with of electronic
microscopy and it is proven that the toxic particles in
the composite matrix are capsulated by the glassy phase
and their inertness is minimized, as a result of which
the solubility in 0.1 mol/dm3 HCl (Na2CO3) after 24 h,
168 h and 720 h is lower in the composites with higher
waste glass content.
Acknowledgements
The authors acknowledge thankfully the financial
support for this work from the Ministry of education and
science of R. Bulgaria (contract BM-07/05) and the Ministry of education and science of R. Macedonia.
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