Researches regarding the obtaining of active slag by using reactive admixtures produced from ferrous and basic scrap SOCALICI ANA, HEPUT TEODOR, ARDELEAN ERIKA, ARDELEAN MARIUS Engineering and Management Department Polytechnic University of Timisoara 5 Revolutiei street, Hunedoara, postal code 331128 ROMANIA {virginia.socalici, heput, erika.ardelean, marius.ardelean}@fih.upt.ro Abstract: - The paper presents the results obtained in laboratory experiments, regarding the obtaining of active slag by using reactive admixtures in briquette form, produced from ferrous and basic scrap. The briquettes produced within the experiments are made of fine and powder scrap, come as waste material from the iron & steel industry, i.e. steel plant dust, dust (sludge) from sintering and blast furnace plants, scale, lime and cement dust. Key-Words: - active slag, ferrous and basic scrap, briquettes, steel-making, lime, steel plant dust, sludge from sintering and blast furnace plants 1 Introduction The briquetting represents the process of transforming fine and powder materials (ores, scrap with less than 8-mm granulation) in pieces with determined geometry (cylindrical, prismatic), through pressing [1]. The briquetting, versus the other procedures used to increase the sizes of the materials (pelletizing and sintering), has the advantage to allow the processing of a various range of scrap with iron content, either from the chemical composition (especially the Fe content) or the granulometric point of view. The installations used to realise the briquetting of materials are either low pressure (up to 75N/mm 2 ) or high pressure (above 75N/mm 2 ) installations. [2,3]. The globally used briquetting methods can be divided in two groups: - Briquetting without addition of binding substances; - Briquetting with addition of binding substances (organic or inorganic binders, i.e. tar, pitch, cement, lime, bentonite, etc.). 2 Experiments regarding the scrap processing Hereinafter, we present the results of the researches performed in order to produce and test cylindrical briquettes with 45mm diameter and 15- 40mm height, along with the results of the resistance tests performed on the briquettes made of recyclable materials [4,5]: - The changing of the briquette resistance according to the weight (in the preparation recipe) of the steel plant dust particles (EAF), rolling-mill scale, sintering-blast furnace sludge, lime, cement; - The influence of some chemical compounds (found in the materials recycled through briquetting) on resistance. To evaluating the resistance qualitative characteristics during handling and transportation of the briquettes, we determined, through experiments, three technological characteristics: - Crack resistance: ] / [ , 2 cm kN A F R f F = (1) where: F f – crack force, [kN]; A – area of the sample (briquette) section, [cm 2 ]. In case of the studied briquettes (cylindrical), the relation (1) becomes: ] / [ , 4 2 2 cm kN d F R f f ⋅ ⋅ = π (2) The crack force F f is considered to be the applied force at which we can see the first cracks. After performing a quite large number of preliminary tests, we consider that this force has the value recorded at τ = 2 seconds. - Crushing resistance: ] / [ , 2 cm kN A F R s S = (3) where: F s – crushing force, [kN]; Selected Topics in Energy, Environment, Sustainable Development and Landscaping ISSN: 1792-5924 / ISSN: 1792-5940 158 ISBN: 978-960-474-237-0
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Researches regarding the obtaining of active slag by using reactive
admixtures produced from ferrous and basic scrap
SOCALICI ANA, HEPUT TEODOR, ARDELEAN ERIKA, ARDELEAN MARIUS
Engineering and Management Department
Polytechnic University of Timisoara
5 Revolutiei street, Hunedoara, postal code 331128
Abstract: - The paper presents the results obtained in laboratory experiments, regarding the obtaining of active
slag by using reactive admixtures in briquette form, produced from ferrous and basic scrap. The briquettes produced within the experiments are made of fine and powder scrap, come as waste material from the iron & steel industry, i.e. steel plant dust, dust (sludge) from sintering and blast furnace plants, scale, lime and cement
dust.
Key-Words: - active slag, ferrous and basic scrap, briquettes, steel-making, lime, steel plant dust, sludge from sintering and blast furnace plants
1 Introduction The briquetting represents the process of transforming fine and powder materials (ores, scrap
with less than 8-mm granulation) in pieces with determined geometry (cylindrical, prismatic),
through pressing [1]. The briquetting, versus the other procedures used to increase the sizes of the materials (pelletizing and
sintering), has the advantage to allow the processing of a various range of scrap with iron content, either
from the chemical composition (especially the Fe content) or the granulometric point of view. The installations used to realise the briquetting
of materials are either low pressure (up to 75N/mm2) or high pressure (above 75N/mm2) installations.
[2,3]. The globally used briquetting methods can be
divided in two groups: - Briquetting without addition of binding
substances;
- Briquetting with addition of binding substances (organic or inorganic binders, i.e. tar, pitch,
cement, lime, bentonite, etc.).
2 Experiments regarding the scrap
processing
Hereinafter, we present the results of the researches performed in order to produce and test cylindrical briquettes with 45mm diameter and 15-
40mm height, along with the results of the resistance tests performed on the briquettes made of recyclable
materials [4,5]:
- The changing of the briquette resistance according to the weight (in the preparation
recipe) of the steel plant dust particles (EAF), rolling-mill scale, sintering-blast furnace sludge, lime, cement;
- The influence of some chemical compounds (found in the materials recycled through
briquetting) on resistance. To evaluating the resistance qualitative
characteristics during handling and transportation of the briquettes, we determined, through experiments, three technological
characteristics: - Crack resistance:
]/[, 2cmkN
A
FR
f
F = (1)
where: Ff – crack force, [kN]; A – area of the sample (briquette) section,
[cm2]. In case of the studied briquettes (cylindrical), the
relation (1) becomes:
]/[,4
2
2cmkN
d
FR
f
f⋅
⋅=π
(2)
The crack force Ff is considered to be the applied
force at which we can see the first cracks. After performing a quite large number of preliminary tests, we consider that this force has the value
recorded at τ = 2 seconds. - Crushing resistance:
]/[, 2cmkN
A
FR s
S = (3)
where: Fs – crushing force, [kN];
Selected Topics in Energy, Environment, Sustainable Development and Landscaping
We obtained 10 recipes to be used in experiments, the chemical composition of the recipes being presented analytically in Table 1 and
graphically in Fig. 1. The scrap chosen for our lab experiments was
processed according to the flow sheet presented in Fig. 2, by using the equipments and installations found in the laboratories of the Engineering Faculty
Fig.1. Chemical composition of experimental recipes
Fig.2. Flow sheet of briquette fabrication
Fig.3. Equipment used for experiments, and the resulting briquettes
3. Results and discussions To determine the quality characteristics, we found the crack and crushing resistance and
calculated the crushing interval of the experimental briquettes. The obtained data were used to determine
the relations that prove the influence of the briquetting charge composition on these parameters.
So, Fig. 4 presents the variation of the crack resistance with the Fe2O3 percentage, resulting that the maximum values of crack resistance are obtained
for contents of 68-72% Fe2O3. Similarly, in case of
Selected Topics in Energy, Environment, Sustainable Development and Landscaping
Fig.6. Rf, Rs, Is versus the percentage of dust from sintering-blast furnace plant
Is = -0,0029(CEA)2 + 0,4146(CEA) - 14,416
R2 = 0,6569
Rf = -0,0061(CEA)2 + 0,8418(CEA)- 28,431
R2 = 0,9188
Rs = -0,009(CEA)2 + 1,2564(CEA) - 42,848
R2 = 0,8913
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
65 66 67 68 69 70 71 72 73 74 75 76
Electric steel plant dust ratio (CEA) , [%]
Rf, Rs, Is, [kN/cm2]
Rf
Rs
Is
Fig.7. Rf, Rs, Is versus the percentage of dust from electric steel plant
Rf = -0,0197(C)2 + 0,347(C) - 0,854
R2 = 0,7827
Rs = 0,0025(C)2 + 0,0598(C) + 0,202
R2 = 0,7816
Is = 0,0221(C)2 - 0,2872(C) + 1,056
R2 = 0,5979
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
5 6 7 8 9
Cement ratio (C) , [%]
Rf, Rs, Is, [kN/cm2]
Rf
Rs
Is
Fig.8. Rf, Rs, Is versus the cement percentage
4. Conclusions Pursuant to researches and their results, we consider important the following conclusions: - The scrap used to produce the briquettes has a
good technological behaviour, the obtained briquettes having the required technical
characteristics to be used in the iron-steel processes; - The briquetting is advantageous because it
allows the processing of a wide range of scrap, either from the chemical composition or granulometric point of view;
- We can obtain briquettes to be used both in the iron and steel making processes;
- In the industrial areas and especially in the iron & steel making areas, which are frequently subject to a strong economical restructuring, we consider
the recovery through the fine scrap briquetting to be
one of the most viable technological solution, suitable to be introduced in the economic circuit. - In case of Hunedoara area, after the strong
restructuring of the former Integrated Steel Plant Hunedoara (currently ArcelorMittal Hunedoara), the
primary flow was completely dismantled: Coke Plant – Sintering Plant – Blast Furnaces – Siemens-Martin Plant. In these conditions, the fine ferrous
scrap (ferrous slag, scale, scale sludge, dust from the Sintering-Blast Furnace Plant) cannot be recycled
through the sintering process anymore. Therefore, the briquetting is the only viable solution. Moreover, the fact that near Hunedoara there is another area
with almost identical problems: OŃelul Roşu – ReşiŃa, represents an additional reason in favour of
the briquetting solution.
Selected Topics in Energy, Environment, Sustainable Development and Landscaping