This paper is closely connected with the complex problem of degradation relating to the refractories of rotary furnace linings in the production of zinc oxide. Zinc oxide can be produced by variety of ways, but the most common method of production which is used in Europe is indirect, i.e. pyrolytic combustion of zinc. This method is also called "French process" of manufacturing ZnO. But this mentioned method of preparation leads to the creation of the enormous amount of zinc slag including chemical complexes of elements Fe, Zn and Al. The mechanism of degradation of the lining leads to slag rests and it is closely connected with the mutual interaction of the aggressive agents with the components of the lining. This process creates a new undesired surface layer which increased the overall thickness of zinc slag. Stuck slag has the influence on rapid degradation of the linings and moreover it also decreases the production quality of ZnO. Analysis results introduced in this paper are significant information for minimizing of degradation of rotary furnaces. 

Anisimov, Evgeniy

Luptáková, Natália

Pešlová, Františka

English

Materials Engineering - Materiálové inžinierstvo (MEMI - E-Journal)

N. Luptáková, E. Anisimov, F. Pešlová: The degradation of lining of rotary furnaces  
in the production of zinc oxide 
Materials Engineering - Materiálové inžinierstvo 21 (2014) 116-121 
116 
THE DEGRADATION OF LINING OF ROTARY 
FURNACES IN THE PRODUCTION OF ZINC OXIDE 
Natália Luptáková1,*, Evgeniy Anisimov2, Františka Pešlová3 
 
1 Institute of Physics of Materials Academy of Science of the Czech Republic, v. v. i., Žižkova 22, 616 62 Brno,  
  Czech Republic 
2
 Department of Materials Engineering, Faculty of Mechanical Engineering, Czech Technical University in  
   Prague, Karlovo nam. 13, 121 32 Prague 2, Czech Republic 
3 
Department of Materials Engineering, Faculty of Industrial Technologies in Púchov, University of Alexander  
  Dubček in Trenčín, I. Krasku 1809/34, 020 01 Púchov, Slovak Republic 
 
*
corresponding author: e-mail: luptakova@ipm.cz  
 
 
Resume 
This paper is closely connected with the complex problem of degradation 
relating to the refractories of rotary furnace linings in the production of zinc 
oxide. Zinc oxide can be produced by variety of ways, but the most common 
method of production which is used in Europe is indirect, i.e. pyrolytic 
combustion of zinc. This method is also called "French process" of 
manufacturing ZnO. But this mentioned method of preparation leads to the 
creation of the enormous amount of zinc slag including chemical complexes of 
elements Fe, Zn and Al. The mechanism of degradation of the lining leads to 
slag rests and it is closely connected with the mutual interaction of the aggressive 
agents with the components of the lining. This process creates a new undesired 
surface layer which increased the overall thickness of zinc slag. Stuck slag has 
the influence on rapid degradation of the linings and moreover it also decreases 
the production quality of ZnO. Analysis results introduced in this paper are 
significant information for minimizing of degradation of rotary furnaces. 
 
Available online: http://fstroj.uniza.sk/journal-mi/PDF/2014/17-2014.pdf 
Article info 
Article history: 
Received 11 October 2013 
Accepted 04 March 2014 
Online 15 September 2014 
 
Keywords: 
Zinc oxide; 
The production of zinc 
oxide; 
Zinc slag; 
Refractories; 
The degradation of rotary 
furnace linings. 
 
ISSN 1335-0803 (print version) 
ISSN 1338-6174 (online version) 
 
1. Introduction 
Zinc oxide (ZnO) has been an important 
industrial material for centuries and is currently 
the subject of considerable new interest [1, 2]. 
ZnO is used by several 100 000 tons per year 
[2]. Zinc oxide is a white solid inorganic 
powder, non-flammable, stable and insoluble in 
water. Size can vary between 0.5 and 5µm, but 
typical size is around 1µm. Zinc oxide occurs 
in nature as mineral zincite. However, in most 
cases zinc oxide is obtained through a technical 
process from zinc [1, 3, 4]. Recent 
investigations reveal that zinc oxide convert 
sun’s is rays into chemical energy in a manner 
similar that of chlorophyll. Zinc oxide is the 
only inorganic material known to act in that 
manner [5]. 
Zinc oxide powder has traditionally been 
used as a white pigment and as an additive to 
rubber. While it has largely been displaced as 
a pigment in paints, its usage in rubber remains 
very important [1]. Everyday items zinc or zinc 
compounds are used in paint pigments and 
coating, plastics, rubbers, cosmetics, medical 
etc. [3]. Indirect production of ZnO starts by 
melting of zinc and following oxidation with 
oxygen from the air in rotary furnaces [1]. 
French process is considered to be the fastest 
and most productive method for industrial 
production of ZnO [6], but according to the 
practical experience, this type of production 
ZnO is not optimal for utilization of the product 
in all technological applications. The 
production of ZnO is based on high speed of 
zinc vapour at speeds 0.1 Mach (30 m.s
-1
) or 
higher and temperature is in the range from 
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N. Luptáková, E. Anisimov, F. Pešlová: The degradation of lining of rotary furnaces  
in the production of zinc oxide 
Materials Engineering - Materiálové inžinierstvo 21 (2014) 116-121 
117 
1300 °C to 1400 °C. Sublimation temperature 
of ZnO is 1p725 °C [3]. The work is also 
focused on the enormous amount of slag 
material. It is closely connected with the 
previous work [7, 8], in which the primary 
material has been studied. Detailed 
investigation of waste material of zinc slag was 
studied in previous work [9].  
The degradation of rotary linings (Fig. 1) 
can be caused different temperature gradients, 
aggressive action of zinc vapour and especially 
incorrect selection of refractory ceramics. The 
given problem is closely connected with the 
systematic approach to the assessment and 
proposal of suitable the ceramics refractories of 
lining for rotary furnaces during the production 
of zinc oxide. 
 
 
Fig. 1. Cracks on the connecting channel in the 
manufacture of zinc oxide. 
(full colour vesrion available online) 
2. Experiment 
Study refractories have been chosen on 
the base of chemical composition (Tab. 1), 
physical and mechanical properties as well as 
technological process for the given materials. 
Static (primary and secondary) corrosion 
tests have been used for analysis and evaluation 
of degradation measurement. Corrosion tests 
were performed at the high-temperature furnace 
(CEKSaSM, TnUAD in Trencin, Slovakia). 
A holes (Ø 10 mm and depth about 
50 mm) was bored into the sample of 
refractories and then the metallic zinc with the 
strictly specified amount (2.0 ± 0.001 g Zn) and 
the given chemical composition 
(Zn = 96.73 wt. %, Fe = 2.2 wt. %, 
Al = 0.5 wt. %, Ni = 0. 29 wt. %, 
Pb = 0.0044 wt. %, Cu = 0.0096 wt. %, 
Cd = 0.0004 wt. %) was inserted and left to act. 
The tests were performed under static 
conditions without the influence of convection 
[10 - 12]. Prepared materials were heated 
gradually (10 °C.min-1) up to temperature 
1400 °C and the whole process of heating took 
120 and following 420 minutes.  
The measurements were performed using 
the stereomicroscopic device NIKON SMZ 
1500 (CVUT in Prague, Czech Republic), SEM 
- JSM 7600F (CVUT in Prague, Czech 
Republic) and X- Ray diffraction Brűcker 8, 
KalfaCo with Co-lamp (SAV Bratislava, 
Slovakia). Setting the measurement - time to 
step is set up in different cps (counts per 
second). 
 
 
Table 1 
Chemical composition of selected refractories (wt. %). 
Refractories CaO Fe2O3 Al2O3 SiO2 SiC MgO 
Chamotte 
MgO 
Silicon Carbide 
- 
1.6 
- 
1.6 
0.5 
- 
41.0 
0.2 
18.0 
53.5 
0.6 
1.7 
- 
- 
75.0 
- 
97.0 
- 
 
 
N. Luptáková, E. Anisimov, F. Pešlová: The degradation of lining of rotary furnaces  
in the production of zinc oxide 
Materials Engineering - Materiálové inžinierstvo 21 (2014) 116-121 
118 
3. Experimental results 
The zinc slag was gradually fed by 
products from reactions with refractory 
materials. During the primary test (at 
a temperature of 909 °C), the sudden reaction 
was observed - the sublimation of zinc was 
followed by oxidation with oxygen from the air. 
There was the conical arrangement of the zinc 
oxide on the surface of material based on MgO 
and chamotte fireclay (Fig. 2). It is important to 
point out that there was the zinc burning in the 
middle of the formed ZnO cone at temperature 
1000 °C. Material based on SiC absorbed the 
ZnO powder. 
Using  X-ray diffraction (Fig. 3) for ZnO 
powder which was formed in a volcanic way, it 
has been found that the resulting compound 
contains only crystalline substances (Fig. 4), 
such as zinkit - ZnO (94 wt. %) and gahnit - 
ZnAl2O4 (6 wt. %). In the case of the samples of 
SiC and MgO, there was not the penetration by 
molten zinc but the given investigated area 
contained the zinc which was burned out (XRD 
analysis determined). In relation to chamotte 
sample, irreversible damage (infiltration) of 
material was occurred and it was caused by 
chemical reactions of chamotte with molten 
zinc. 
 
Fig. 2. Formed zinc oxide on the surface of chamotte. 
(full colour vesrion available online) 
The difference between primary and 
secondary corrosion test is connected with the 
different construction of samples of refractories 
(samples representing the substrate were 
covered by a layer of the same material as the 
substrate). The purpose of the structural changes 
of the previous measurements was to prevent 
the creation of zinc oxide by the volcanic effect. 
Prepared materials were heated gradually up to 
temperature 1400 °C and the whole process of 
heating took 420 minutes (Fig. 5).  
There was a change of refractory material 
based on silicon carbide. Sintered cristobalite 
(β-SiO2) was occurred on the surface of refractories 
 
0 10 20 30 40 50 60 70 80
0
2000
4000
6000
8000
10000
12000
14000
16000
 
 
 ZnO
I/
a
.u
2  
 
Fig. 3. The difractogram of selected samples for formed zinc oxide. 
(full colour vesrion available online) 
 
N. Luptáková, E. Anisimov, F. Pešlová: The degradation of lining of rotary furnaces  
in the production of zinc oxide 
Materials Engineering - Materiálové inžinierstvo 21 (2014) 116-121 
119 
 
 
Fig. 4. Zincit, LOM. 
(full colour vesrion available online) 
Fig. 5. Selected refractories in the elevator furnace 
with temperature 1,400 °C;a) chamotte, b) MgO, 
c) SiC. 
(full colour vesrion available online) 
 
 
 
Fig. 6. The surface of refractory material (SiC-based) 
wit created cristobalite after the secondary corrosion 
test, LOM. 
(full colour vesrion available online) 
Fig. 7. The interface of refractory material (SiC-
based) between a) original material before test and 
b) after test, SEM. 
(full colour vesrion available online) 
 
 
Fig. 8. EDX analysis of selected surface (SiC-based material), 
SEM. 
(full colour vesrion available online) 
N. Luptáková, E. Anisimov, F. Pešlová: The degradation of lining of rotary furnaces  
in the production of zinc oxide 
Materials Engineering - Materiálové inžinierstvo 21 (2014) 116-121 
120 
(SiC-based) (Fig. 6). The interaction of zinc 
with the refractory led to occurrence of willemit 
(Zn2SiO4) which was identified by XRD 
analysis. In Fig. 7 is detail of view interface 
refractory on the based SiC before and after the 
secondary corrosion test. 
Not occurred to mutual influence 
refractory (based on MgO) with zinc in corrosion 
testing of refractory samples. During the 
corrosion tests, the influence of zinc on 
refractory material (based on SiC) was 
recognized. The mentioned fact was also proven 
by help of LOM, SEM investigations of the 
structures (Fig. 8). EXD analysis was also used 
for the investigation of surfaces (Tab. 2) and it 
also showed that there is the influence by zinc.  
 
4. Conclusions  
From the study, the following 
conclusions can be drawn: 
- Temperature is important critical factor 
affecting the corrosion processes in the system 
refractory - melted zinc - atmosphere. 
Penetration rate of elements into matrix of 
refractory is increased exponentially with 
increasing temperature; 
- Primary factor for selecting the most 
suitable refractory materials is a basic 
character of ceramic components compatible 
with the aggressive components of slag 
materials (for example molten zinc). In 
relation to material properties are primary 
knowledge of porosity, the phase interface, 
morphology and the grain size of the 
investigated material; 
- Open porosity of refractories 
contributed to absorption of Zn into the matrix 
of given material; 
- On the reaction surface of sample of 
MgO and SiC, there was the occurrence of 
minority physico-chemical reactions. Zinc in the 
form of dendrites was detected at the interface 
zinc/refractory. There was not the penetration of 
the slag into matrix of refractory materials as 
well as adhesive action on the microscopic level 
was not observed. 
- Depending on the chemical 
composition, we can conclude that there is not 
influence of MgO materials on the quality of the 
produced ZnO. Zinc oxide was produced in the 
range of chemical concentrations which are 
suitable for its usage. 
- Present Zn, ZnO and Fe not penetrated 
into the matrix of SiC-based refractories when 
they are in the contact with the surface of 
refractory material. The liquid slag is not 
penetrated into the study material; 
- It can be pointed out that the used SiC-
based refractories (75.0 wt. % SiC and the rest 
representing the 25 or 15 % can be oxides, such 
as Al2O3, SiO2) have impact on the mutual 
interaction between the alkaline and acids 
constituents. 
- In case of application of MgO 
refractories, we recommend to keep conditions 
relating to the gradual  temperature increase 
(200 °C.h-1) in the furnace and the finishing of  
the production cycle  should be completed  by 
gradual cooling; 
- We recommend reducing the overall 
open porosity of the selected materials based on 
alkaline magnesium oxide while the maximum 
total value should be 12%. This is a sufficient 
level of porosity which is required to maintain 
resistance to thermal shocks as well as suitable 
insulation properties. 
 
Table 2  
EDX analysis of contains of elements (SiC-based sample is show in fig. 5) (wt. %). 
Selected Spectrum Ca Zn Al O Si 
Spectrum 1 
Spectrum 2 
Spectrum 3 
Sum. Spectrum  
2.27 
4.15 
0.01 
1.71 
2.57 
13.83 
0.12 
1.76 
12.85 
21.58 
0.07 
5.76 
48.64 
39.85 
1.80 
23.22 
24.25 
11.50 
69.61 
37.99 
 
N. Luptáková, E. Anisimov, F. Pešlová: The degradation of lining of rotary furnaces  
in the production of zinc oxide 
Materials Engineering - Materiálové inžinierstvo 21 (2014) 116-121 
121 
Acknowledgment 
This work has been supported by TAČR No. 
TA02011121. 
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[2] C. Klingshirn et al: 65 years of ZnO research – 
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[3] D. Galusek, K. Ghillányová: Zinc Oxide, In: 
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The degradation of lining of rotary furnaces in the production of zinc oxide

This paper is closely connected with the complex problem of degradation relating to the refractories of rotary furnace linings in the production of zinc oxide. Zinc oxide can be produced by variety of ways, but the most common method of production which is used in Europe is indirect, i.e. pyrolytic combustion of zinc. This method is also called "French process" of manufacturing ZnO. But this mentioned method of preparation leads to the creation of the enormous amount of zinc slag including chemical complexes of elements Fe, Zn and Al. The mechanism of degradation of the lining leads to slag rests and it is closely connected with the mutual interaction of the aggressive agents with the components of the lining. This process creates a new undesired surface layer which increased the overall thickness of zinc slag. Stuck slag has the influence on rapid degradation of the linings and moreover it also decreases the production quality of ZnO. Analysis results introduced in this paper are significant information for minimizing of degradation of rotary furnaces.  </p

The degradation of lining of rotary furnaces in the production of zinc oxide

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