Comparison of possibilities the blast furnace and cupola slag ...

of

ISSN (1897-3310) Volume 10 Special Issue 2/2010 15 – 18

FOUNDRY ENGINEERING

2/2

ARCHIVES

Published quarterly as the organ of the Foundry Commission of the Polish Academy of Sciences

Comparison of possibilities the blast furnace and cupola slag utilization by concrete production a

D. Baricová a,*, A. Pribulová a, P. Demeter a Department of Iron Metallurgy and Foundry, Technical University of Košice, Faculty of Metallurgy, Park Komenského 14, 040 23 Košice, Slovak republic *Corresponding author. E-mail address: [email protected] Received 20.05.2010; accepted in revised form 05.06.2010

Abstract In process of pig iron and cast iron production secondary raw materials and industrial wastes are formed The most abundant secondary product originating in these processes are furnace slag. Blast furnace slag and cupola furnace slag originates from melting of gangue parts of metal bearing materials, slag forming additions and coke ash. In general, slag are compounds of oxides of metallic and non-metallic elements, which form chemical compounds and solutions with each other and also contain small volume of metals, sulfides of metals and gases. Chemical, mineralogical and physical properties of slag determinate their utilisation in different fields of industry. The paper presents results from the research of the blast furnace and cupola furnace slag utilization in the concrete production. Pilot experiments of the concrete production were performed, by that the blast furnace and cupola furnace slag with a fractions of 0–4mm; 4–8mm; 8–16mm were used as a natural substitute. A cupola furnace slag and combination of the blast furnace and cupola furnace slag were used in the experiments. The analysis results show that such concretes are suitable for less demanding applications. Keywords: Environment Protection, Mechanical Properties, Cupola Furnace slag, Blast furnace slag, Concrete Production

1. Introduction In the technological process of the steel plant not only are main products being produced, but simultaneously by-products are created too. They have the characteristics of secondary materials and of industrial waste. Some of the main products of iron and cast making are solid light ash, waste gases, technological fluids and mostly slag. Metallurgical slag represents roughly 80% of by-products, which develop in the process of pig iron and cast iron production. Foundry slag, as opposed to blastfurnace and steel-making slag, are not used in Slovakia at all. In

most cases they are deposited on a dump, where they take useful land. There were experiments made with production of concrete under conditions at the Department of Ferrous Metallurgy and Foundry, where natural aggregate was completely replaced by blast-furnace gravel or demetallized steel-making slag [1]. Favourable results of experiments and at the same time chemical similarity of blast-furnace slag and cupola slag have started a new series of experiments dealing with possibilities of cupola-slag utilization in production of concrete.

ARCHIVES OF FOUNDRY ENGINEERING Volume 10, Special Issue 2/2010, 15-18

15

2. C Comparisson of thee blast furrnace and cup pola furnace slag

nd other knownn wollasstonite (CaO.SiO2), fayalite ((2FeO.SiO2) an structu ural componentts, especially coombinations of SiO2 – Al2O3 – CaO, Fig. 4.

Slag from cupoola furnace (Figg. 1) is mostly resembling blaastfurnnace slag by theeir chemical composition, propperties and natuure (Figg. 2). It results from comparisson of chemicaal composition of cupoola slag and blaast-furnace slagg that cupola sllag is of the sam me basiic oxide componnents as blast-ffurnace slag, Taable 1.

Fig. 1. Cupolaa furnace slag

Fiig. 3. Structure of blast-furnacee slag (magnificcation 200x)

Fig. 2. Blast furnace f slag Table 1. a Rannge of chemicaal composition cupola furnacee slag (CFS) and blasst furnace slag (BFS) ( CaO SiiO2 Al2O3 MgO MnO FeO [%] [% %] [%] [%] [% %] [%] 0,5-30 1-44 1-15 CFS S 20-50 255-55 5-20 36-50 300-42 7-18 2-12 0,44-1,1 0,4-1,11 BFS S Basic, and at the same tim me, one of thee most importaant chem mical properties of slag is basiicity. In the casse of blast-furnaace slagg, basicity is in the region of the level of accid slag (B = 1 to 1,1). In the case off cupola slag, thhe basicity may ranged from accid to basic slag. From mineraloogic point of vieew, blast-furnacce slags consistt of CaO.Al2O3.SiO2 minerals of gehhlenite and akkermanite (2C 2CaaO.MgO.2SiO2), ) and i in additionn, monticelllite (CaO O.MgO.SiO2), merwinite 3CaO.MgO.S SiO2, rankinnite 3CaaO.2SiO2, dicallcium silicate 2CaO.SiO2, psseudowollastonnite CaO O.SiO2 and siliccate glass mayy occur in the structure as weell, Fig. 3. The structural composition off cupola slag iss, as for acid slag, creaated especially by silicates. The T most frequuent minerals are a

16

Fig g. 4. Structure of o cupola furnacce slag (magnifi fication 200x) Fiinal physical prroperties of theese slag are giv ven not only byy their chemical c compposition, but to the great exten nt, by a way inn which h the molten slag is processeed, i.e. cooled down and sett. Accorrding to the way w of coolingg down, reduceed or increasedd crystaallization of paarticular structuural componen nts occurs. The resultiing ratio of cryystalline and gllassy phase is the t major factoor influeencing their grrindability. Theeir mineralogiccal compositionn and siize of crystals influences its reesulting strength h properties andd abrasiion resistance. The porosity iincurred by leaaking gases, the solubiility in slag off which is decreasing during cooling, has a consid derable impactt on resistance against frost as well as the streng gth. It is necessary to t realize that these types of o slag have noo utilizaation in metallurgic cycle annd therefore it is necessary too modiffy and use them m outside the meetallurgic produ uction.


3. D Descriptioon of expeeriments Semi-operationnal experimentts have been performed undder condditions of Deppartment of Feerrous Metallurrgy and Founddry. Initiial requirementt to use 100% % proportion of o cupola slag in prodduction of conccrete mixtures was w not feasiblle, since resultiing strenngth propertiees were not sufficient. Byy this reason, a com mbination of cuppola slag and blast-furnace b slaag was appliedd in folloowing experimeents. Grain sizee proportion of the finest fractiion of bblast-furnace slag 0-4 mm waas replaced by cupola slag with w ratioos of 90:10, 80::20 and 70:30. Chemical com mposition of blaast-furnace slagg and cupola sllag usedd in experimentts is shown in Table T 2. Table 2. Cheemical composition of cupola furnace (CFS) and blast furnaace slagg (BFS) CaO [%]

SiO2 [%]

Al2O3 [% %]

MgO [%]

FeO [%]

Fe mett. [%]]

CFS S

33,68

55,19

7,29

0,49

1,15

1,688

BFS S

40,00

38,00

7,00

9,00

1,1

-

The first step consisted in a determinatioon of a standaard desccribing the roaad concrete. Itss designation is i STN 73 61223: 19966, STN ISO 4103: 1995 [2], [3]. This standaard describes whhat typee and fractions of aggregate arre to be used. At A the same tim me, stanndard describes type of cemennt, plastifying and a air-entrainiing agennts. There are values defined which are to be obtained at quallity evaluation of given concrrete over givenn time of 28 daays, e.g. tensile bendinng of concrete, cylinder strenngth of concreete, conssistence of freshh concrete, etc. Concrete consiists of cement, aggregate, water and additioons. As tthe standard defines, high-strength Portland cement c is used for prodduction of conncretes. The volume v of cem ment used for all preppared mixes was w 7.93 kg. The T ratio of small-grained s a and coarrse-grained agggregate was deteermined by Fulller's curve. Thhus, a peercentage ratio for particular fractions from m total volume of aggrregate was speecified. Blast-fuurnace and cupoola slag were ussed as thhe aggregate. Ratios R and voluumes of slag useed in experiments are sshown in Tablee 3. Drinking waterr was used as mixing water for production of conccrete and as a curing water at setting and hardening of the t conccrete. "Stachement 2000" was used suuperplastifier and a "Microporan" was used as an aeraating agent. Thhe volumes addded into concrete were specified by prroducer of thesee additions. Tootal voluume of mix (aaggregate, cem ment, water) plaaced into stirriing deviice was approxximately 95 kg, from which appproximately 35 l of cconcrete will be b produced. Such volume of concrete will w sufffice for producttion of requesteed number of teest coupons: thrree beam ms with dimensions of 100 x 100 x 400 mm m and three cubbes withh dimensions off 150 x 150 x 1550 mm. The weighing of aggregate and cement were w poured innto stirrring device annd stirred for a minute. After A stirring, the t requuested volume of water, plasttifying and air--entraining agents weree added into thhe mix. Then, all the mix was w stirred for 30

or slump test - a minuttes. After stirrinng, a test samplle was taken fo determ mination of the consistence off fresh concrete. In all preparedd mixess, the height determined d by slump test corrresponded withh standaard values rangging from 50 mm to 90 mm m, Fig 5 and 6. 6 Then, after their fillling-in, mouldss were hardeniing, Fig. No. 7. 7 They hardened 24 hoours in the mouuld and after unmoulding u theyy were submerged intoo water. The saamples hardeneed in water untiil they were w provided for f a test after 228 days. Table 3. position of conccrete mixtures Comp Fractioon of cupola slagg in mm

A (100% %) B (10% %) C (20% %) D (30% %)

Fraction off blast furnace slag in mm

H 2O [1]

0-4 [kg]

4-8 [kg]

8-16 [kg]

0-4 [kg]

4-8 [kg]

8-16 [kg]

33,6

2,9

5,5

-

-

-

6,6

3,4

-

-

30,2

2,9

5,5

6,2

6,7

-

-

26,9

2,9

5,5

5,8

10,1

-

-

23,5

2,9

5,5

6,1

Fig. 5. Slum mp test

Fig. 6. Slum mp test

Fig. 7 Filled testing staandardized mou ulds


17 7

We consider the evaluation of concrete mixtures and hardened concrete to be very important part in suggesting of new types of concretes. The tests of hardened concrete include: the influence of hydrating degree on properties of hardened concrete, the estimation of porosity of cement stone, determination of humidity, absorptivity and capillarity of concrete, determination of volume changes of concrete, shrinking and intumescence, chemical analysis of concrete, compression strength, tensile strength, tensile bending, etc. [4]. Table 4. Resulting compression strength and tensile bending after 28 days

A (100%) B (10%) C (20%) D (30%) STN 73 6123 (roud concrete) STN ENV 206 –C 8/10 (plain concrete) STN ENV 206 –C 12/15 (plain concrete)

compression strength [MPa] 3,2 10 12 13

tensile bending [MPa]

28

4,0

8

-

12

-

1 3,3 4,3 3,8

As for our experiments, tensile bending and compression strength tests were made. The tests were carried out in Engineering and Building Testing Institution. The resulting values of strength are shown in Table 4 which includes standardized values for road concrete as well as the ones of common concrete of lower grades. It results from Table 4 that the concrete mixtures using blastfurnace and cupola slag do not comply with STN 73 6123 for road concretes. However mixtures B, C and D complies with the standard for concretes with lower strength properties, so called

common concretes, STN ENV 206 –C 8/10 and STN ENV 206 – C 12/15.

4. Conclusions Approximately 1,950 tons of cupola slag is annually produced in Slovakia. All the production of the slag is dumped. In semi-operational experiments, the possibilities of utilization of blast-furnace and cupola slag in concrete production as a substitution of natural aggregate were examined. For semioperational experiments, various ratios of these slag were combined. It results from the measured mechanical properties that such concretes do not suit for very stressed road concretes, but they are suitable for common grades of concretes. They are plain concretes with volume mass of 2,000 - 2,400 kg.m-3. It is possible to use these concretes for building of base or levelling layers, foundations of structures, core parts of framed structures, etc.

Acknowledgements This work was supported by the Slovak Research and Development agency under the contract No. APVV-0180-07 (more information: http://web.tuke.sk/hf-kmzaz/apvv/index.html)

References [1] P. Demeter, D. Baricová, Ľ. Mihok, P. Ivanišin, Influence of different factors on cencrete produced from the blast furnance, Iron and Steelmaking: 17. medzinárodná vedecká konferencia: Vysoké Tatry, Štrbské pleso, 17.-19. októbra 2007: Acta Metallurgica Slovaca. roč. 13, č. 5 (2007), s. 120-123. ISSN 1335-1532. [2] STN 73 6123: 1996. [3] STN ISO 4103: 1995. [4] J. Slimák, Príspevok k otázkam navrhovania zloženia betónových zmesí, Zborník prednášok zo seminára Výroba betónu, TU Košice, Stavebná fakulta, 2000, s. 38 – 44.

Porównanie możliwości wykorzystania żużla wielkopiecowego i żeliwiakowego do produkcji betonu Streszczenie W referacie przedstawiono wyniki badań w zakresie wykorzystania żużla żeliwiakowego oraz mieszaniny żużla żeliwiakowego i żużla wielkopiecowego do produkcji betonu. Stosowano trzy frakcje żużli: 0-4 mm, 4-8 mm oraz 8-16 mm jako zamienniki naturalnego kruszywa. Przeprowadzono analizę chemiczną, mineralogiczną oraz ziarnową tych żużli. Stwierdzono, że betony wyprodukowane z udziałem tych żużli, co prawda nie spełniają wymagań stawianych betonom do budowy dróg, ale mogą one być wykorzystywane w mniej odpowiedzialnych konstrukcjach budowlanych.

18
