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Analysis of defects in the cooling system and in grey cast iron staves of No. 3-Ph blast furnace

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EU fl f3¿ñ
Commission of the European Communities
technical steel research
Reduction of ores
DEVELOPMENT OF IMPROVED PLATE COOLERS
(STAVES) FOR BLAST FURNACES
Parti
Analysis of defects in the cooling system and in grey cast iron
staves of l\lo.3-Ph blast furnace
Report
EUR 9327/1 EN
Blow-up from microfiche original Commission of the European Communities
technical steel research
Reduction of ores
DEVELOPMENT OF IMPROVED PLATE COOLERS
(STAVES) FOR BLAST FURNACES
Parti
Analysis of defects in the cooling system and in grey cast iron
staves of No.3-Ph blast furnace
U. PÜCKOFF, CH. KNOCHE
HOESCH HÜTTENWERKE A.G.
Eberhardtstraße, 12
D-4600 DORTMUND
Contract No 7210-AA/113
(1.4.1980 - 31.3.1985)
FINAL REPORT
PARL HP"?. rUi'ioth.
Directorate-General
Science, Research and Development
NX
1986 CL EUR 9327/I EN Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
L-2920 LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting
on behalf of the Commission is responsible for the use which might be made of
the following information
© ECSC-EEC-EAEC, Brussels • Luxembourg, 1986 III-
CONTENTS.
1. Introduction
2. Aims of the project
3. General data for No.3-Ph blast furnace
4. Description of furnace condition
4.1 Intermediate inspection of stave cooling after 2.8
mill, t of iron production
4.2n of furnace condition after blowing out
4.2.1 Bottom,hearth
4.2.2 Stave cooling region (bosh,belly,stack)
4.2.2.1 Circular row 1 2r row 2
4.2.2.3 Circular row 3 4r row 4
4.2.2.5 Circular row 5 6r row 6
4.2.2.7 Circular rows 7 and 8
5. Description of preparatory work in connection with the
research project after shut down of No.3-Ph furnace.
5.1- Photographic documentation
5.1.1 Staves in furnace
5.1.2s removed for investigation purposes
5.1.3 Staves of circular rows 1,7 and 8 ..
5.2 Preparation of staves for metallographic investigations
5.3 Residual thickness measurements -IV-
6. Investigations on samples from gap between staves
and shell
6.1 Results of visual observations
6.2s of chemical investigations on samples from
gap between staves and shell
6.3 Mineralogical observations
7. No.3-Ph blast furnace cooling system
7.1 Description of evaporative cooling
7.2 Behaviour of cooling system during furnace campaign
7.2.1 Pulsations
7.2.2 Thermal loading of plate coolers
7.2.3 Leakage location
7.3 Condition of evaporative cooling system after blowing
out of No.3-Ph furnace
7.3.1 Time related pattern of cooling pipe failure and
installation of cooling boxes
7.3.2 Effectiveness and life of pipe restoration
7.3.3 Origin of cooling pipe defects
8. Macroscopic investigations
8.1 Sample preparation
8.2 Crack formation
8.2.1kn in region of cooling pipe and stave edge
resion
8.2.2 Crack formation in rib region e
8.2.2.1kn in cast ribs 2 Crack, formation between cast ribs
8.2.2.3 Crackn in transition region between ribs and
main casting
8.3 Gap formation in cooling pipe region
8.3.1 Possibilities of gap formation
8.3.2 ' Gap formation in cooling pipe region of extracted staves
8.3.2.1 Cooling pipes still completely covered with cast material 2 Partially exposed cooling pipes or cracks in main casting
8.4 Pipe wall thicknesses; deformation of cooling pipes
8.5 Thermal zone formation V-
8.6 Defects in stave manufacture
8.6.1 Cooling pipe location
8.6.2 Core supports for cooling pipe fixing
8.6.3 Shrinkage,defective areas
9. Microscopic investigations
9.1 Structure formation of casting under influence of heat
9.2 Adherent iron/slag layers
9.3 Cooling pipes
9.3.1 Structure
9.3.2 Deposits on interior surfaces of pipes
9.4 Core supports
10 Investigations on materials of castings,cooling pipes
and fixing screws
10.1 Grey iron cast material,delivery condition
10.2 Analysis of grey cast material'after furnace campaign
10.3 Chemical and mechanical investigations on cooling pipe
material after furnace campaign
10.3.1l analyses of cooling pipe material
10.3.2 Mechanical investigations on cooling pipe material
10.4 Fixing screws for securing staves to shell
10.4.1g screw material analyses
10.4.2 Macroscopic and microscopic investigations
11 Interpretation of causes of stave wear at No 3-Ph furnace
11.1 Melting off processes
11.2 Abrasion due to descending burden and dust-laden furnace
gases
11.2.1n due to descending burden
11.2.2 Abrasion due to dust-laden furnace gases
11.3 Changes in the mechanical properties of cast material
due to temperature effect
11.4 Crack formation
11.5 Cooling pipe failures and restoration
11.6 Evaporative cooling -VI
12. Final observations
12.1 Stave construction
12.2e arrangement in furnace,stave fixing
12.3 Plate cooler material
12.4 Furnace operation
12.5 Miscellaneous
13 Summary
Bibliography
Tables
Illustrations. VII
List of Tables«
Table 1 Constructional details of No.3-Ph blast furnace
(Furnace campaign from Feb.1976 to April 1980)
Table 2 Characteristic values(yearly averages) for No.3-Ph
blast furnace for furnace campaign Feb. 1976 to April
1980
Table 3 Properties of refractory insulating concrete between
staves and furnace shell.
Table 4 Chemical analyses of scabs between back of staves
and furnace shell at No.3'-Ph furnace
m
Table 5 Converted chemical analyses from able 4 (Fe-compon-
ents.C, C0_, H^O eliminated)
Table 6 Technical details of evaporative cooling,No.3-Ph furnace
Table 7 Deposits on cooling pipe interiors from No.3-Ph furnace
staves.
Table 8 Summary of results of investigations on No.3-Ph furnace
staves from foundry/wDrks reports (campaign 02/1976 to
04/1980)
Table 9 Chemical analyses of cast material
Table 10 Chemical analyses of pipe material(St; 35.8 Material No.1.0305)
Table 11 Mechanical-technological tests on sections of cooling
pipes from No.3-Ph furnace staves (St 35.8/II DIN 17175)
Table 12 Material analyses of stave fixing screws from No,3-Ph
furnace.