The testing cycle, described in the paper, included fine-grained coke breeze granulation tests and iron concentrate sintering tests with the use of selected granulate samples. The use of granulated coke breeze in the sintering process results in a higher process efficiency, shorter sintering duration and fuel saving

B. Oleksiak

J. Stecko

L. Blacha

M. Niesler

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37METALURGIJA 53 (2014) 1, 37-39M. NIESLER, J. STECKO, L. BLACHA, B. OLEKSIAKAPPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE SINTERINGReceived – Prispjelo: 2013-04-25Accepted – Prihvaćeno: 2013-06-15Preliminary Note – Prethodno priopćenjeISSN 0543-5846METABK 53(1) 37-39 (2014)UDC – UDK 669.052:662.742.87:66.099=111M. Niesler, J. Stecko - Gliwice, Institute for Ferrous Metallurgy), Gli-wice, PolandL. Blacha, B. Oleksiak - Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, Katowice, PolandThe testing cycle, described in the paper, included fi ne-grained coke breeze granulation tests and iron concentrate sintering tests with the use of selected granulate samples. The use of granulated coke breeze in the sintering proc-ess results in a higher process effi  ciency, shorter sintering duration and fuel saving.Key words: ore sintering, coke breeze, granulation, centrifugal pelletizerINTRODUCTIONAmounts of generated yearly waste fi ne-grained coal materials in coal, coke and chemical industries are relatively high, which considerably intensifi es explora-tion of new methods of their management. These waste materials include coal slurries, fl otation tailings, coal abrasive coke dusts, fi ne-grained fractions of coke breeze and coal soot. A shared property of these materi-als is their grain size, mostly below 2 mm. The most common way of the above material management is their utilisation for production of coal blends, coal concen-trates and energetic fuels. They are also used by other industries – the best example is metallurgy where at-tempts of replacing conventional reducers (e.g. coke or coke breeze) with fi ne-grained coal materials have been observed for several years [1-3].The fuel used in iron ore sintering processes is coke breeze. Its combustion yields enough amounts of heat which is delivered to the sinter mix. One of the factors that signifi cantly affect the course of coke breeze com-bustion is its grain size. Many studies and industrial practices have shown that coarse-grained coke breeze causes delayed combustion, which leads to higher heat energy consumption during the process. On the other hand, fi ne-grained fuel reduces permeability of the sin-ter mix and, therefore, the effi ciency of the process it-self. For this reason, the use of coke breeze fraction with grains sized below 1 mm is avoided on the sinter belt. In the present paper, results of a study on coke breeze undersize grain granulation in the aspect of the produced agglomerate utilisation in the process of iron ore sintering have been discussed. Effects of the ag-glomerate on overall fuel consumption during the proc-ess and sinter output have been determined [4-10].RESEARCH METHODOLOGYThe proposed testing cycle included fi ne-grained coke breeze granulation tests and iron concentrate sin-tering tests with the use of selected granulate samples. For the granulation tests, coke breeze fractions with the grain size below 1 mm were used. The grain analysis is presented in Table 1.Table 1 The grain analysis of investigated coke breezeGrain Class/mmEach class fraction / %Test numberAverage1 2 3 4 51 - 0.5 34,0 32,9 33,8 33,8 33,8 33,70,50-0,25 22,0 21,1 21,0 19,5 20,4 20,8below 0,25 44,0 46,0 45,2 46,8 45,8 45,5Average grain / mm 0,39 0,38 0,39 0,38 0,39 0,39The granulation tests were performed in a GS 106 centrifugal pelletizer (Figure 1). Such devices feature a mobile component (a rotating disc), while its walls re-main stationary. During centrifugation of the disc, the material is frequently rotated, which leads to its granu-lation. For the above granulation tests, burnt lime and hydrated lime were used as binding materials. The gran-ulation process parameters were as follows:• granulation time – 2 min• disc rotation speed – 300 rpm• water content – about 14 – 15 %• binding material addition – 10 %.The iron concentrate sintering tests with the use of produced coke breeze undersize grain granulate were performed on a sinter pan. A schematic diagram of the entire sintering system is presented in Figure 2.The sintering tests were performed with the use of alkaline-stable sinter mix. The alkalinity was adjusted by maintaining a proper fraction of limestone in the sin-tering feed. In Tables 2 and 3, compositions of the in-vestigated sinter mixes are presented.38  METALURGIJA 53 (2014) 1, 37-39M. NIESLER et al.: APPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE...RESULTS AND DISCUSSIONResults of the mix sintering tests are presented in Table 4 which contains basic data regarding the sinter-ing process: its duration, sintering rate, process effi cien-cy and post-stabilisation sintering output. Graphic inter-pretations of the results are shown in Figures 3 - 4.Based on the analysis of results, improvement of the selected parameters of iron concentrate sintering with the use of fi ne-grained coke breeze granulate has been observed, including: improved process effi ciency from 4 to 9 % reduced sintering duration from 5 to 9 %  reduced consumption of basic coke breeze frac-tions.Figure 1 The centrifugal pelletizerFigure 2 The schematic diagram of laboratory sintering system:(1 - Sinter pan, 2 - Sampling points for exhaust gas analysis,3 - Exhaust gas neutralisation system 4 - Orifi ce meters,5 - Choke valves, 6 - Air delivery line, 7 - Air fl ow measurements, 8 - Oxygen delivery line, 9 - The cap of exhaust gas delivery line to the pan, 10 - Exhaust gas temperature measurements, 11 - Funnel - W1, W2 – exhaust gas fans)Table 2  Composition of the mix used for sintering tests with granulated coke breeze fraction and hydrated limeNo. Components H2O Fe SiO2 CaO MgO% % % %1 Concentrate I 10,10 67,94 4,48 0,10 0,312 Concentrate II 9,80 65,03 8,05 0,39 0,543 Concentrate III 10,05 65,53 5,75 0,15 0,124 Fine ore 4,20 60,27 11,02 0,78 0,215 Burnt lime 0,00 0,65 0,82 79,80 18,116 Slag 4,18 18,74 14,77 38,57 7,137 Dusts 0,00 51,21 6,61 10,85 1,458 Mill scale 4,10 72,02 1,80 1,24 0,719 Dolomite 5,62 0.88 1,24 30,90 19,2010 Lime for granulation H 0,00 0,00 0,00 89,00 1,0011 Limestone 0,92 0,25 1,90 53,86 0,4912 Coke breeze (11% ash) 10,00 1,13 4,13 0,72 0,11Table 3  Composition of the mix used for sintering tests with granulated coke breeze and burnt limeNo. Components H2O Fe SiO2 CaO MgO% % % %1 Concentrate I 10,10 67,94 4,48 0,10 0,312 Concentrate II 9,80 65,03 8,05 0,39 0,543 Concentrate III 10,05 65,53 5,75 0,15 0,124 Agloore 4,20 60,27 11,02 0,78 0,215 Burnt lime 0,00 0,65 0,82 79,80 18,116 Slag 0–8 4,18 18.74 14,77 38,57 7,137 Dusts 0,00 51.21 6,61 10,85 1,458 Mill scale 4,10 72,02 1,80 1,24 0,719 Dolomite 5,62 0,88 1,24 30,90 19,2010 Lime for granulation B 0,00 0,65 0,82 79,80 18,1111 Limestone 0,92 0,25 1,90 53,86 0,4912 Coke breeze (11% pop.) 10,00 1,13 4,13 0,72 0,11Table 4  Average results of sintering tests with the use of granulated coke breeze fractionParameter Comp. mixMixes with granulated coke breeze undersize grainHydrated limeBurnt limeI. Mix characteristics1. Humidity / % 7,47 7,33 7,532. Bulk density / kg/m3 1895,6 1887,9 1890,43. Flow resistance / s 5,51 5,47 5,20II. Process parameters1. Sintering duration / min 14,03 13,36 12,832.  Negative pressure (initial and fi nal) / mm H2O1150/9101110/8801060/8703.  Exhaust gas temperature (under the pan) / oC464,7 435,0 473,94. Sintering vertical rate 39,33 41,20 42,865.  Process effi  ciency (charge sinter) / kg/m2·h1221,7 1272,9 1334,66.  Solid fuel consumption (dry) / kg/t of the sinter54,68 54,07 54,017.  Post-stabilisation sinter output / %84,95 85,13 85,6039METALURGIJA 53 (2014) 1, 37-39M. NIESLER et al.: APPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE...Moreover, the other process parameters have not been found deteriorated. The fi ndings are highly con-sistent with the results of studies conducted in the Nip-pon Steel Corporation where for fi ne-grained coke breeze granulation, a centrifugal pelletizer was also ap-plied [11], which is illustrated in Figure 5.CONCLUSIONThe investigations have proved that the fi ne-grained coke breeze fraction can be agglomerated by means of the granulation method using a centrifugal pelletizer. The method yields a coarser-grained coke breeze frac-tion which can be used in ferriferous material sintering processes. Moreover, this application leads to a higher process effi ciency, shorter sintering duration and fuel saving.REFERENCES[1]  J. Łabaj, M. Słowikowski, W. Żymła, J. Lipart: Metalurgi-ja 52 (2013) 1, 68-70.[2]  J. Lipart, T. Matuła, M. Niesler, L. Blacha, J. Filipczyk: Metalurgija 52 (2013) 4, 493-498.[3] M. Niesler, L. Blacha, J. Łabaj, T. Matuła: Metalurgija 52 (2013) 4, 521-524.[4]  B. Beer, W. Beier: Stahl und Eisen (1991) 11, 25-37.[5]  H Beer, K. Kersting, H. Muller: Hut. Swiat. Biul. Inf. 25 (1992) 4, 25-42.[6]  N. Gugus: Izwiestija Vyssz. Uczeb. Zav., Czernaja Mietal-lurgija (1990) 11, 8 - 10.[7]  S.N. Pietruszow, W.L. Bosyj: Metallurg (1982) 5, 9-10.[8]  E.F. Vegman, J.S. Karabasow, W. S. Balawin: Izv. Vyssh. Ucheb. Zav. Czernaja Mietallurgija (1971) 3, 23-26.[9]  B. Boranbaev, M., Poljakova: Stal (1993) 5, 86-91.[10]  C. Mo, C. Teo, I. Hamilton, J. Morrison: ISIJ International (1997) 4, 350-357.[11]  Y. Hosotani, N. Konno, J. Shibata: ISIJ International 35 (1995) 11, 1340 − 1347.Note:  A. Sliwakowska is Responsible for English language, Gliwice, PolandFigure 3  Eff ects of the binding material type of granulated coke breeze undersize grain on the mix permeability (fl ow resistance), sintering duration and sintering vertical rateFigure 4  Eff ects of the binding material type of coke breeze undersize grain on the process effi  ciency, fuel consumption and sinter outputFigure 5  Comparative results of laboratory sintering tests with the use of iron concentrate mix and granulated coke breeze [11]

English

Application of fine-grained coke breeze fractions in the process of iron ore sintering

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37 METALURGIJA 53 (2014) 1, 37-39M. NIESLER, J. STECKO, L. BLACHA, B. OLEKSIAKAPPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE SINTERINGReceived – Prispjelo: 2013-04-25Accepted – Prihvaćeno: 2013-06-15Preliminary Note – Prethodno priopćenjeISSN 0543-5846METABK 53(1) 37-39 (2014)UDC – UDK 669.052:662.742.87:66.099=111M. Niesler, J. Stecko - Gliwice, Institute for Ferrous Metallurgy), Gli-wice, PolandL. Blacha, B. Oleksiak - Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, Katowice, PolandThe testing cycle, described in the paper, included fi  ne-grained coke breeze granulation tests and iron concentrate sintering tests with the use of selected granulate samples. The use of granulated coke breeze in the sintering proc-ess results in a higher process effi   ciency, shorter sintering duration and fuel saving.Key words: ore sintering, coke breeze, granulation, centrifugal pelletizerINTRODUCTIONAmounts of generated yearly waste ﬁ  ne-grained coal materials in coal, coke and chemical industries are relatively high, which considerably intensiﬁ  es explora-tion of new methods of their management. These waste materials include coal slurries, ﬂ  otation tailings, coal abrasive coke dusts, ﬁ   ne-grained fractions of coke breeze and coal soot. A shared property of these materi-als is their grain size, mostly below 2 mm. The most common way of the above material management is their utilisation for production of coal blends, coal concen-trates and energetic fuels. They are also used by other industries – the best example is metallurgy where at-tempts of replacing conventional reducers (e.g. coke or coke breeze) with ﬁ  ne-grained coal materials have been observed for several years [1-3].The fuel used in iron ore sintering processes is coke breeze. Its combustion yields enough amounts of heat which is delivered to the sinter mix. One of the factors that signiﬁ  cantly affect the course of coke breeze com-bustion is its grain size. Many studies and industrial practices have shown that coarse-grained coke breeze causes delayed combustion, which leads to higher heat energy consumption during the process. On the other hand, ﬁ  ne-grained fuel reduces permeability of the sin-ter mix and, therefore, the efﬁ  ciency of the process it-self. For this reason, the use of coke breeze fraction with grains sized below 1 mm is avoided on the sinter belt. In the present paper, results of a study on coke breeze undersize grain granulation in the aspect of the produced agglomerate utilisation in the process of iron ore sintering have been discussed. Effects of the ag-glomerate on overall fuel consumption during the proc-ess and sinter output have been determined [4-10].RESEARCH METHODOLOGYThe proposed testing cycle included ﬁ  ne-grained coke breeze granulation tests and iron concentrate sin-tering tests with the use of selected granulate samples. For the granulation tests, coke breeze fractions with the grain size below 1 mm were used. The grain analysis is presented in Table 1.Table 1 The grain analysis of investigated coke breezeGrain Class/mmEach class fraction / %Test numberAverage1234 51 - 0.5 34,0 32,9 33,8 33,8 33,8 33,70,50-0,25 22,0 21,1 21,0 19,5 20,4 20,8below 0,25 44,0 46,0 45,2 46,8 45,8 45,5Average grain / mm0,39 0,38 0,39 0,38 0,39 0,39The granulation tests were performed in a GS 106 centrifugal pelletizer (Figure 1). Such devices feature a mobile component (a rotating disc), while its walls re-main stationary. During centrifugation of the disc, the material is frequently rotated, which leads to its granu-lation. For the above granulation tests, burnt lime and hydrated lime were used as binding materials. The gran-ulation process parameters were as follows:• granulation time – 2 min• disc rotation speed – 300 rpm• water content – about 14 – 15 %• binding material addition – 10 %.The iron concentrate sintering tests with the use of produced coke breeze undersize grain granulate were performed on a sinter pan. A schematic diagram of the entire sintering system is presented in Figure 2.The sintering tests were performed with the use of alkaline-stable sinter mix. The alkalinity was adjusted by maintaining a proper fraction of limestone in the sin-tering feed. In Tables 2 and 3, compositions of the in-vestigated sinter mixes are presented.38   METALURGIJA 53 (2014) 1, 37-39M. NIESLER et al.: APPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE...RESULTS AND DISCUSSIONResults of the mix sintering tests are presented in Table 4 which contains basic data regarding the sinter-ing process: its duration, sintering rate, process efﬁ  cien-cy and post-stabilisation sintering output. Graphic inter-pretations of the results are shown in Figures 3 - 4.Based on the analysis of results, improvement of the selected parameters of iron concentrate sintering with the use of ﬁ  ne-grained coke breeze granulate has been observed, including:  improved process efﬁ  ciency from 4 to 9 %  reduced sintering duration from 5 to 9 %    reduced consumption of basic coke breeze frac-tions.Figure 1 The centrifugal pelletizerFigure 2 The schematic diagram of laboratory sintering system:(1 - Sinter pan, 2 - Sampling points for exhaust gas analysis,3 - Exhaust gas neutralisation system 4 - Orifi  ce meters,5 - Choke valves, 6 - Air delivery line, 7 - Air fl  ow measurements, 8 - Oxygen delivery line, 9 - The cap of exhaust gas delivery line to the pan, 10 - Exhaust gas temperature measurements, 11 - Funnel - W1, W2 – exhaust gas fans)Table 2   Composition of the mix used for sintering tests with granulated coke breeze fraction and hydrated limeNo. Components H2OF eS i O 2 CaO MgO%%%%1C o n c e n t r a t e  I 1 0 , 1 06 7 , 9 44 , 4 80 , 1 00 , 3 12 Concentrate II 9,80 65,03 8,05 0,39 0,543 Concentrate III 10,05 65,53 5,75 0,15 0,124 Fine ore 4,20 60,27 11,02 0,78 0,215 Burnt lime 0,00 0,65 0,82 79,80 18,116 Slag 4,18 18,74 14,77 38,57 7,137 Dusts 0,00 51,21 6,61 10,85 1,458 Mill scale 4,10 72,02 1,80 1,24 0,719 Dolomite 5,62 0.88 1,24 30,90 19,2010 Lime for granulation H 0,00 0,00 0,00 89,00 1,0011 Limestone 0,92 0,25 1,90 53,86 0,4912 Coke breeze (11% ash) 10,00 1,13 4,13 0,72 0,11Table 3   Composition of the mix used for sintering tests with granulated coke breeze and burnt limeNo. Components H2OF eS i O 2 CaO MgO%%%%1C o n c e n t r a t e  I 1 0 , 1 0 6 7 , 9 44 , 4 80 , 1 0 0 , 3 12 Concentrate II 9,80 65,03 8,05 0,39 0,543 Concentrate III 10,05 65,53 5,75 0,15 0,124 Agloore 4,20 60,27 11,02 0,78 0,215 Burnt lime 0,00 0,65 0,82 79,80 18,116S l a g  0 – 8 4 , 1 81 8 . 7 4 1 4 , 7 7 3 8 , 5 77 , 1 37 Dusts 0,00 51.21 6,61 10,85 1,458 Mill scale 4,10 72,02 1,80 1,24 0,719 Dolomite 5,62 0,88 1,24 30,90 19,2010 Lime for granulation B 0,00 0,65 0,82 79,80 18,1111 Limestone 0,92 0,25 1,90 53,86 0,4912 Coke breeze (11% pop.) 10,00 1,13 4,13 0,72 0,11Table 4   Average results of sintering tests with the use of granulated coke breeze fractionParameter Comp. mixMixes with granulated coke breeze undersize grainHydrated limeBurnt limeI. Mix characteristics1. Humidity / % 7,47 7,33 7,532. Bulk density / kg/m3 1895,6 1887,9 1890,43. Flow resistance / s 5,51 5,47 5,20II. Process parameters1. Sintering duration / min 14,03 13,36 12,832.   Negative pressure (initial and fi  nal) / mm H2O1150/9101110/8801060/8703.   Exhaust gas temperature (under the pan) / oC464,7 435,0 473,94. Sintering vertical rate 39,33 41,20 42,865.   Process effi   ciency (charge sinter) / kg/m2·h1221,7 1272,9 1334,66.   Solid fuel consumption (dry) / kg/t of the sinter54,68 54,07 54,017.   Post-stabilisation sinter output / %84,95 85,13 85,6039 METALURGIJA 53 (2014) 1, 37-39M. NIESLER et al.: APPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE...Moreover, the other process parameters have not been found deteriorated. The ﬁ  ndings are highly con-sistent with the results of studies conducted in the Nip-pon Steel Corporation where for ﬁ  ne-grained  coke breeze granulation, a centrifugal pelletizer was also ap-plied [11], which is illustrated in Figure 5.CONCLUSIONThe investigations have proved that the ﬁ  ne-grained coke breeze fraction can be agglomerated by means of the granulation method using a centrifugal pelletizer. The method yields a coarser-grained coke breeze frac-tion which can be used in ferriferous material sintering processes. Moreover, this application leads to a higher process efﬁ  ciency, shorter sintering duration and fuel saving.REFERENCES[1]   J. Łabaj, M. Słowikowski, W. Żymła, J. Lipart: Metalurgi-ja 52 (2013) 1, 68-70.[2]   J. Lipart, T. Matuła, M. Niesler, L. Blacha, J. Filipczyk: Metalurgija 52 (2013) 4, 493-498.[3]  M. Niesler, L. Blacha, J. Łabaj, T. Matuła: Metalurgija 52 (2013) 4, 521-524.[4]   B. Beer, W. Beier: Stahl und Eisen (1991) 11, 25-37.[5]   H Beer, K. Kersting, H. Muller: Hut. Swiat. Biul. Inf. 25 (1992) 4, 25-42.[6]   N. Gugus: Izwiestija Vyssz. Uczeb. Zav., Czernaja Mietal-lurgija (1990) 11, 8 - 10.[7]   S.N. Pietruszow, W.L. Bosyj: Metallurg (1982) 5, 9-10.[8]   E.F. Vegman, J.S. Karabasow, W. S. Balawin: Izv. Vyssh. Ucheb. Zav. Czernaja Mietallurgija (1971) 3, 23-26.[9]   B. Boranbaev, M., Poljakova: Stal (1993) 5, 86-91.[10]   C. Mo, C. Teo, I. Hamilton, J. Morrison: ISIJ International (1997) 4, 350-357.[11]   Y. Hosotani, N. Konno, J. Shibata: ISIJ International 35 (1995) 11, 1340 − 1347.Note:   A. Sliwakowska is Responsible for English language, Gliwice, PolandFigure 3   Eff  ects of the binding material type of granulated coke breeze undersize grain on the mix permeability (fl  ow resistance), sintering duration and sintering vertical rateFigure 4   Eff  ects of the binding material type of coke breeze undersize grain on the process effi   ciency, fuel consumption and sinter outputFigure 5   Comparative results of laboratory sintering tests with the use of iron concentrate mix and granulated coke breeze [11]

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37METALURGIJA 53 (2014) 1, 37-39M. NIESLER, J. STECKO, L. BLACHA, B. OLEKSIAKAPPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE SINTERINGReceived – Prispjelo: 2013-04-25Accepted – Prihvaćeno: 2013-06-15Preliminary Note – Prethodno priopćenjeISSN 0543-5846METABK 53(1) 37-39 (2014)UDC – UDK 669.052:662.742.87:66.099=111M. Niesler, J. Stecko - Gliwice, Institute for Ferrous Metallurgy), Gli-wice, PolandL. Blacha, B. Oleksiak - Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, Katowice, PolandThe testing cycle, described in the paper, included fi ne-grained coke breeze granulation tests and iron concentrate sintering tests with the use of selected granulate samples. The use of granulated coke breeze in the sintering proc-ess results in a higher process effi  ciency, shorter sintering duration and fuel saving.Key words: ore sintering, coke breeze, granulation, centrifugal pelletizerINTRODUCTIONAmounts of generated yearly waste ﬁ ne-grained coal materials in coal, coke and chemical industries are relatively high, which considerably intensiﬁ es explora-tion of new methods of their management. These waste materials include coal slurries, ﬂ otation tailings, coal abrasive coke dusts, ﬁ ne-grained fractions of coke breeze and coal soot. A shared property of these materi-als is their grain size, mostly below 2 mm. The most common way of the above material management is their utilisation for production of coal blends, coal concen-trates and energetic fuels. They are also used by other industries – the best example is metallurgy where at-tempts of replacing conventional reducers (e.g. coke or coke breeze) with ﬁ ne-grained coal materials have been observed for several years [1-3].The fuel used in iron ore sintering processes is coke breeze. Its combustion yields enough amounts of heat which is delivered to the sinter mix. One of the factors that signiﬁ cantly affect the course of coke breeze com-bustion is its grain size. Many studies and industrial practices have shown that coarse-grained coke breeze causes delayed combustion, which leads to higher heat energy consumption during the process. On the other hand, ﬁ ne-grained fuel reduces permeability of the sin-ter mix and, therefore, the efﬁ ciency of the process it-self. For this reason, the use of coke breeze fraction with grains sized below 1 mm is avoided on the sinter belt. In the present paper, results of a study on coke breeze undersize grain granulation in the aspect of the produced agglomerate utilisation in the process of iron ore sintering have been discussed. Effects of the ag-glomerate on overall fuel consumption during the proc-ess and sinter output have been determined [4-10].RESEARCH METHODOLOGYThe proposed testing cycle included ﬁ ne-grained coke breeze granulation tests and iron concentrate sin-tering tests with the use of selected granulate samples. For the granulation tests, coke breeze fractions with the grain size below 1 mm were used. The grain analysis is presented in Table 1.Table 1 The grain analysis of investigated coke breezeGrain Class/mmEach class fraction / %Test numberAverage1 2 3 4 51 - 0.5 34,0 32,9 33,8 33,8 33,8 33,70,50-0,25 22,0 21,1 21,0 19,5 20,4 20,8below 0,25 44,0 46,0 45,2 46,8 45,8 45,5Average grain / mm 0,39 0,38 0,39 0,38 0,39 0,39The granulation tests were performed in a GS 106 centrifugal pelletizer (Figure 1). Such devices feature a mobile component (a rotating disc), while its walls re-main stationary. During centrifugation of the disc, the material is frequently rotated, which leads to its granu-lation. For the above granulation tests, burnt lime and hydrated lime were used as binding materials. The gran-ulation process parameters were as follows:• granulation time – 2 min• disc rotation speed – 300 rpm• water content – about 14 – 15 %• binding material addition – 10 %.The iron concentrate sintering tests with the use of produced coke breeze undersize grain granulate were performed on a sinter pan. A schematic diagram of the entire sintering system is presented in Figure 2.The sintering tests were performed with the use of alkaline-stable sinter mix. The alkalinity was adjusted by maintaining a proper fraction of limestone in the sin-tering feed. In Tables 2 and 3, compositions of the in-vestigated sinter mixes are presented.38  METALURGIJA 53 (2014) 1, 37-39M. NIESLER et al.: APPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE...RESULTS AND DISCUSSIONResults of the mix sintering tests are presented in Table 4 which contains basic data regarding the sinter-ing process: its duration, sintering rate, process efﬁ cien-cy and post-stabilisation sintering output. Graphic inter-pretations of the results are shown in Figures 3 - 4.Based on the analysis of results, improvement of the selected parameters of iron concentrate sintering with the use of ﬁ ne-grained coke breeze granulate has been observed, including: improved process efﬁ ciency from 4 to 9 % reduced sintering duration from 5 to 9 %  reduced consumption of basic coke breeze frac-tions.Figure 1 The centrifugal pelletizerFigure 2 The schematic diagram of laboratory sintering system:(1 - Sinter pan, 2 - Sampling points for exhaust gas analysis,3 - Exhaust gas neutralisation system 4 - Orifi ce meters,5 - Choke valves, 6 - Air delivery line, 7 - Air fl ow measurements, 8 - Oxygen delivery line, 9 - The cap of exhaust gas delivery line to the pan, 10 - Exhaust gas temperature measurements, 11 - Funnel - W1, W2 – exhaust gas fans)Table 2  Composition of the mix used for sintering tests with granulated coke breeze fraction and hydrated limeNo. Components H2O Fe SiO2 CaO MgO% % % %1 Concentrate I 10,10 67,94 4,48 0,10 0,312 Concentrate II 9,80 65,03 8,05 0,39 0,543 Concentrate III 10,05 65,53 5,75 0,15 0,124 Fine ore 4,20 60,27 11,02 0,78 0,215 Burnt lime 0,00 0,65 0,82 79,80 18,116 Slag 4,18 18,74 14,77 38,57 7,137 Dusts 0,00 51,21 6,61 10,85 1,458 Mill scale 4,10 72,02 1,80 1,24 0,719 Dolomite 5,62 0.88 1,24 30,90 19,2010 Lime for granulation H 0,00 0,00 0,00 89,00 1,0011 Limestone 0,92 0,25 1,90 53,86 0,4912 Coke breeze (11% ash) 10,00 1,13 4,13 0,72 0,11Table 3  Composition of the mix used for sintering tests with granulated coke breeze and burnt limeNo. Components H2O Fe SiO2 CaO MgO% % % %1 Concentrate I 10,10 67,94 4,48 0,10 0,312 Concentrate II 9,80 65,03 8,05 0,39 0,543 Concentrate III 10,05 65,53 5,75 0,15 0,124 Agloore 4,20 60,27 11,02 0,78 0,215 Burnt lime 0,00 0,65 0,82 79,80 18,116 Slag 0–8 4,18 18.74 14,77 38,57 7,137 Dusts 0,00 51.21 6,61 10,85 1,458 Mill scale 4,10 72,02 1,80 1,24 0,719 Dolomite 5,62 0,88 1,24 30,90 19,2010 Lime for granulation B 0,00 0,65 0,82 79,80 18,1111 Limestone 0,92 0,25 1,90 53,86 0,4912 Coke breeze (11% pop.) 10,00 1,13 4,13 0,72 0,11Table 4  Average results of sintering tests with the use of granulated coke breeze fractionParameter Comp. mixMixes with granulated coke breeze undersize grainHydrated limeBurnt limeI. Mix characteristics1. Humidity / % 7,47 7,33 7,532. Bulk density / kg/m3 1895,6 1887,9 1890,43. Flow resistance / s 5,51 5,47 5,20II. Process parameters1. Sintering duration / min 14,03 13,36 12,832.  Negative pressure (initial and fi nal) / mm H2O1150/9101110/8801060/8703.  Exhaust gas temperature (under the pan) / oC464,7 435,0 473,94. Sintering vertical rate 39,33 41,20 42,865.  Process effi  ciency (charge sinter) / kg/m2·h1221,7 1272,9 1334,66.  Solid fuel consumption (dry) / kg/t of the sinter54,68 54,07 54,017.  Post-stabilisation sinter output / %84,95 85,13 85,6039METALURGIJA 53 (2014) 1, 37-39M. NIESLER et al.: APPLICATION OF FINE-GRAINED COKE BREEZE FRACTIONS IN THE PROCESS OF IRON ORE...Moreover, the other process parameters have not been found deteriorated. The ﬁ ndings are highly con-sistent with the results of studies conducted in the Nip-pon Steel Corporation where for ﬁ ne-grained coke breeze granulation, a centrifugal pelletizer was also ap-plied [11], which is illustrated in Figure 5.CONCLUSIONThe investigations have proved that the ﬁ ne-grained coke breeze fraction can be agglomerated by means of the granulation method using a centrifugal pelletizer. The method yields a coarser-grained coke breeze frac-tion which can be used in ferriferous material sintering processes. Moreover, this application leads to a higher process efﬁ ciency, shorter sintering duration and fuel saving.REFERENCES[1]  J. Łabaj, M. Słowikowski, W. Żymła, J. Lipart: Metalurgi-ja 52 (2013) 1, 68-70.[2]  J. Lipart, T. Matuła, M. Niesler, L. Blacha, J. Filipczyk: Metalurgija 52 (2013) 4, 493-498.[3] M. Niesler, L. Blacha, J. Łabaj, T. Matuła: Metalurgija 52 (2013) 4, 521-524.[4]  B. Beer, W. Beier: Stahl und Eisen (1991) 11, 25-37.[5]  H Beer, K. Kersting, H. Muller: Hut. Swiat. Biul. Inf. 25 (1992) 4, 25-42.[6]  N. Gugus: Izwiestija Vyssz. Uczeb. Zav., Czernaja Mietal-lurgija (1990) 11, 8 - 10.[7]  S.N. Pietruszow, W.L. Bosyj: Metallurg (1982) 5, 9-10.[8]  E.F. Vegman, J.S. Karabasow, W. S. Balawin: Izv. Vyssh. Ucheb. Zav. Czernaja Mietallurgija (1971) 3, 23-26.[9]  B. Boranbaev, M., Poljakova: Stal (1993) 5, 86-91.[10]  C. Mo, C. Teo, I. Hamilton, J. Morrison: ISIJ International (1997) 4, 350-357.[11]  Y. Hosotani, N. Konno, J. Shibata: ISIJ International 35 (1995) 11, 1340 − 1347.Note:  A. Sliwakowska is Responsible for English language, Gliwice, PolandFigure 3  Eff ects of the binding material type of granulated coke breeze undersize grain on the mix permeability (fl ow resistance), sintering duration and sintering vertical rateFigure 4  Eff ects of the binding material type of coke breeze undersize grain on the process effi  ciency, fuel consumption and sinter outputFigure 5  Comparative results of laboratory sintering tests with the use of iron concentrate mix and granulated coke breeze [11]

Application of fine-grained coke breeze fractions in the process of iron ore sintering

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