researches regarding the obtaining of active slag by using

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/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

ISSN: 1792-5924 / ISSN: 1792-5940 158 ISBN: 978-960-474-237-0

A – area of the sample (briquette) section, [cm2].

In case of the studied briquettes, the relation (3) becomes:

]/[,4 2

2cmkN

d

FR s

s⋅

⋅=π

(4)

Based on the preliminary observations, we

considered that the crushing force has the value recorded at τ = 12 seconds.

- Crushing interval:

]/[, 2cmkNRRR fsfs −=∆ (5)

Regarding the possibility to apply the results in the practical recycling, we took into account the fact

that any research should comply with the permissible values for the above-mentioned resistances [6,7]. So, we can affirm that, in order to

resist during handling and transportation, the

briquettes should meet the following resistance values:

Rf > 0.2, [kN/cm2] (6) Rs = (1.2-1.35) Rf , [kN/cm2] (7)

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

of Hunedoara: vibratory screening installation, Sartorius analytical balance, mixing drums, scrap

briquetting experiment installation and compression test machine (used to determine the crack and

crushing resistance, respectively). In Fig. 3, we present some pictures taken during the experiments.

Table.1. Recipes chemical composition

Recipe

no.

Recipes chemical composition, [%]

SiO2 FeO Fe2O3 P2O5 S C Al2O3 CaO MgO MnO others

oxide

R1 4,15 2,69 68,53 0,22 0,20 3,19 3,56 8,82 0,51 3,20 4,94

R2 4,07 2,63 69,16 0,22 0,19 3,01 3,49 8,74 0,50 3,24 4,75

R3 4,00 2,58 69,80 0,22 0,18 2,83 3,43 8,66 0,48 3,28 4,55

R4 4,17 2,52 70,43 0,22 0,17 2,66 3,65 8,06 0,45 3,31 4,35

R5 4,10 2,46 71,07 0,23 0,16 2,48 3,58 7,98 0,43 3,35 4,16

R6 4,03 2,41 71,70 0,23 0,14 2,30 3,52 7,90 0,41 3,39 3,97

R7 3,47 2,35 72,35 0,23 0,13 2,12 2,86 8,85 0,42 3,44 3,78

R8 3,40 2,30 72,98 0,23 0,12 1,95 2,79 8,77 0,40 3,48 3,58

R9 3,33 2,24 73,62 0,23 0,11 1,77 2,72 8,69 0,38 3,51 3,39

R10 3,26 2,19 74,25 0,23 0,10 1,59 2,65 8,61 0,36 3,55 3,20

0,00 20,00 40,00 60,00 80,00

SiO2

FeO

Fe2O3

P

S

C

Al2O3

CaO

MgO

MnO

others oxide

Recipes chemical composition

Element (oxide) quantity, [%]

R10

R9

R8

R7

R6

R5

R4

R3

R2

R1


ISSN: 1792-5924 / ISSN: 1792-5940 159 ISBN: 978-960-474-237-0

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


ISSN: 1792-5924 / ISSN: 1792-5940 160 ISBN: 978-960-474-237-0

the Al2O3 content, we recommend values of 3.3-3.7% Al2O3 (Fig.5), because the briquettes need

higher crack and crushing resistances, due to the binding role of alumina.

When analysing the global influence of the main components of the experimental recipes on the crack resistance and interval (Fig. 6-8), we found a

maximisation of the resistance characteristics of the briquettes in the following conditions:

- 13-15% dust from sintering-blast furnace plant; - 69-71% dust from electric steel plant;

- approx. 8% cement.

y = -0,0151x2 + 2,1247x - 74,243

R2 = 0,9194

y = -0,0268x + 2,5043

R2 = 0,5065

0,4

0,45

0,5

0,55

0,6

0,65

0,7

68 70 72 74 76

Fe2O3 quantity, [%]

Crack strengh, [kN/cm2]]

Fig.4. Influence of the Fe2O3 percentage on the crack resistance

y = 0,1745x + 0,0383

R2 = 0,8552

y = -0,1455x2 + 1,0898x - 1,382

R2 = 0,8843

0,4

0,45

0,5

0,55

0,6

0,65

0,7

2,5 3 3,5 4

Al2O3 quantity, [%]

Crack strengh, [kN/cm2]

Fig.5. Influence of the Al2O3 percentage on the crack resistance

Rf = -0,0061(AF)2 + 0,1815(AF) - 0,6995

R2 = 0,9188

Rs = -0,009(AF)2 + 0,262(AF) - 1,0816

R2 = 0,8913

Is= -0,0029(AF)2 + 0,0805(AF) - 0,3821

R2 = 0,6569

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

8 9 10 11 12 13 14 15 16 17 18 19

Agglomerat-blowing furnace dust ratio (AF) , [%]

Rf, Rs, Is, [kN/cm2]

Rf

Rs

Is


ISSN: 1792-5924 / ISSN: 1792-5940 161 ISBN: 978-960-474-237-0

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

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

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.


ISSN: 1792-5924 / ISSN: 1792-5940 162 ISBN: 978-960-474-237-0

References:

[1] Project no. 31-098/2007: Prevention and

fighting pollution in the steel making, energetic

and mining industrial areas through the

recycling of small-size and powdering wastes,

Program PN2 – Consortium – CO. Responsable:

Prof. dr. eng. Teodor HepuŃ, Beneficiary: CNMP, Romania.

[2] Buzea, O., Blowing furnace guide, vol.I, Lithography of “Dunărea de Jos” University, Galati, 2000.

[3] Ilie, A., Research on materials high recovery from steel powder, PhD thesis, Scientific

supervisor: Prof.dr.eng. Dragomir I., University Politehnica Bucureşti, 1999.

[4] Socalici, A., Heput, T., Ardelean, E., Ardelean, M., Research regarding using the wastea with

carbon content in siderurgical industry, Journal of Environmental Protection end Ecology, book

2, 2010, pp. 465-470. [5] Constantin, C., Engineered to produce pig iron

in blast furnace, PRINTECH Publishing House, Bucuresti, 2002.

[6] Nicolae, M., Todor, P., Licurici, M., Mândru, C.,

Ioana, A., Semenescu, M., Predescu, C., Şerban, V., Calea, G., Sohaciu, M., Parpala, D., Nicolae,

A., Sustainable development in steel by

secondary material recovery, PRINTECH Publishing House, Bucureşti, 2004.

[7] Nicolae, M., Melinte, I., Bălănescu, M., HriŃac, M., Savin, D., Popescu, L., Florea, R., Sohaciu,

M., Matei, E., Nicolae, A., Review procedures in ecometalurgic management, Fair Partners

Publishing House, Bucureşti, 2002.


ISSN: 1792-5924 / ISSN: 1792-5940 163 ISBN: 978-960-474-237-0

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