Researches regarding the obtaining of active slag by using reactive admixtures produced from ferrous and basic scrap

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1 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 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 ) or high pressure (above 75N/mm ) installations. [,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.). 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: Ff RF =, [ kn / cm ] (1) A where: F f crack force, [kn]; A area of the sample (briquette) section, [cm ]. In case of the studied briquettes (cylindrical), the relation (1) becomes: 4 F f R, [ kn / cm f = ] () π d 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 = seconds. - Crushing resistance: Fs RS =, [ kn / cm ] (3) A where: F s crushing force, [kn]; ISSN: / ISSN: ISBN:

2 A area of the sample (briquette) section, [cm ]. In case of the studied briquettes, the relation (3) becomes: 4 Fs R, [ kn / cm s = ] (4) π d Based on the preliminary observations, we considered that the crushing force has the value recorded at τ = 1 seconds. - Crushing interval: R = R R, [ kn / cm ] (5) fs s f 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: R f > 0., [kn/cm ] (6) R s = ( ) R f, [kn/cm ] (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., 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. Recipe no. Table.1. Recipes chemical composition Recipes chemical composition, [%] SiO FeO Fe O 3 P O 5 S C Al O 3 CaO MgO MnO others oxide R1 4,15,69 68,53 0, 0,0 3,19 3,56 8,8 1 3,0 4,94 R 4,07,63 69,16 0, 0,19 3,01 3,49 8,74 0 3,4 4,75 R3 4,00,58 69,80 0, 0,18,83 3,43 8,66 8 3,8 4,55 R4 4,17,5 73 0, 0,17,66 3,65 8,06 5 3,31 4,35 R5 4,10,46 71,07 0,3 0,16,48 3,58 7,98 3 3,35 4,16 R6 4,03,41 71,70 0,3 0,14,30 3,5 7,90 1 3,39 3,97 R7 3,47,35 7,35 0,3 0,13,1,86 8,85 3,44 3,78 R8 3,40,30 7,98 0,3 0,1 1,95,79 8,77 0 3,48 3,58 R9 3,33,4 73,6 0,3 0,11 1,77,7 8,69 0,38 3,51 3,39 R10 3,6,19 74,5 0,3 0,10 1,59,65 8,61 0,36 3,55 3,0 others oxide Recipes chemical composition R10 R9 R8 R7 R6 R5 R4 R3 R R1 MnO MgO CaO AlO3 C S P FeO3 FeO SiO 0,00 0,00 40,00 60,00 80,00 Element (oxide) quantity, [%] ISSN: / ISSN: ISBN:

3 Selected Topics in Energy, Environment, Sustainable Development and Landscaping Fig.1. Chemical composition of experimental recipes Fig.. Flow sheet of briquette fabrication Fig.3. Equipment used for experiments, and the resulting briquettes 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 FeO3 percentage, resulting that the maximum values of crack resistance are obtained for contents of 68-7% FeO3. Similarly, in case of 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 ISSN: / ISSN: ISBN:

4 the Al O 3 content, we recommend values of % Al O 3 (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: % dust from sintering-blast furnace plant; % dust from electric steel plant; - approx. 8% cement. Crack strengh, [kn/cm ]] y = -0,068x +,5043 R = 065 y = -0,0151x +,147x - 74,43 R = 0, Fe O 3 quantity, [%] Fig.4. Influence of the Fe O 3 percentage on the crack resistance 5 Crack strengh, [kn/cm ] 5 5 y = 0,1745x + 0,0383 R = 0,855 y = -0,1455x + 1,0898x - 1,38 R = 0,8843,5 3 3,5 4 Al O 3 quantity, [%] Fig.5. Influence of the Al O 3 percentage on the crack resistance 0,9 0,8 Rs = -0,009(AF) + (AF) - 1,0816 R = 0,8913 Rf, Rs, Is, [kn/cm ] Rf Rs Is 0,3 0, 0,1 0 Rf = -0,0061(AF) + 0,1815(AF) R = 0,9188 Is= -0,009(AF) + 0,0805(AF) - 0,381 R = Agglomerat-blowing furnace dust ratio (AF), [%] ISSN: / ISSN: ISBN:

5 Fig.6. R f, R s, I s versus the percentage of dust from sintering-blast furnace plant 0,9 0,8 Rs = -0,009(CEA) + 1,564(CEA) - 4,848 R = 0,8913 Rf, Rs, Is, [kn/cm ] 0,3 0, 0,1 Rf = -0,0061(CEA) + 0,8418(CEA)- 8,431 R = 0,9188 Is = -0,009(CEA) + 146(CEA) - 14,416 R = 569 Rf Rs Is Electric steel plant dust ratio (CEA), [%] Fig.7. R f, R s, I s versus the percentage of dust from electric steel plant 0,9 0,8 Rs = 0,005(C) + 0,0598(C) + 0,0 R = 816 Rf, Rs, Is, [kn/cm] 0,3 0, 0,1 Is = 0,01(C) - 0,87(C) + 1,056 R = 979 Rf = -0,0197(C) + 0,347(C) - 0,854 R = 87 Rf 0 Rs Is Cement ratio (C), [%] Fig.8. R f, R s, I s 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: / ISSN: ISBN:

6 References: [1] Project no /007: Prevention and fighting pollution in the steel making, energetic and mining industrial areas through the recycling of small-size and powdering wastes, Program PN Consortium CO. Responsable: Prof. dr. eng. Teodor HepuŃ, Beneficiary: CNMP, Romania. [] Buzea, O., Blowing furnace guide, vol.i, Lithography of Dunărea de Jos University, Galati, 000. [3] Ilie, A., Research on materials high recovery from steel powder, PhD thesis, Scientific supervisor: Prof.dr.eng. Dragomir I., University Politehnica Bucureşti, [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, 010, pp [5] Constantin, C., Engineered to produce pig iron in blast furnace, PRINTECH Publishing House, Bucuresti, 00. [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, 004. [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, 00. ISSN: / ISSN: ISBN: