The experimental study of the granulation process

Baosteel Techrical ResearchVolune 6 ,Number 2 ,June 2012 ,Page 3The experimental study of the granulation processXIONG LinIronmaking and Sustainability Division, Research Institute, Baoshan Iron & Stcel Co, Ltd, Shanghai 201900, ChinaAbstract: This paper deals with a comparative research between two processes of granulation, namely mini-pelletizedsintering ( MPS ) and hybrid pelletized sintering ( HPS)，focusing on aspects such as the balling effect, production,quality , and mineralography and meallurgical performance of sinter. The results indicate that both methods can result ina satisfying capability in balling effect and metallurgical performance of sinter, qualified to meet the plant productionrequirements, but when the granulation time and granulating moisture are set to around 6 minutes and 7. 0% respectively,MPS is better than HPS.Key words: granulation methods; balling efet; production an quality of sinterdoi: 10. 3969/j issn. 1674 - 3458.2012.02. 001through a pelletizing disk, and then proceeds to theoperation of solid fuel coating, where the quasi-particles1 Introductionroll and get covered with a layer of powdered coke orGood granulation helps to result in an improvedcoal. Granulation effect of the HPS is quite satisfactory ,but the handling capacity is relatively small, puttingpemneability of the material layer and increase thproduction and quality of the sinter. Enhancingconstraints on sintering plants to increase the production.granulation in the mixing prvcess can improve theIn contrast, MPS is characterized by large handlingadhesion of fine material to the nuclear particles. As acapacity and good granulation effect， and it alsoresult, particles with evenly dispersed particle size willfacilitates powdered fuel coating. In this paper, thform, the sintering bed permeability will be improved,two granulation processes were compared by studyingand higher sintering productivity will be achieved.he balling effect, the production， quality, miner-Therefore , rescarchers from all over the world have beenalograpby and metallurgical propertics of sinter indedicated to the study on the mixing and granulatingdifferent granulation time lengths and moistures.technologies of sintering raw material， and havedeveloped two kinds of processes; one-mixing2 Materials and Methodsgranulation process and two mixing granulation process.2.1 Raw materialCurently the most widely used pelltized sinteringgranulation processes are China's MPS ( three sectionsThe chemical compositions of raw materials anof cylinder granulating) and Japan ' s HPS (two sectionsshown in Table 1. Table 1 shows that the iron contentof cylinder and a section of disc granulating)02]. HPSof the two kinds of iron ores reaches 64. 90% andwas developed by Japan's NKK， who in 198866. 36% respectively , and the SiO2 content is relativelyimplemented the process in the 530 m2 sintering machinelow, only 3. 75% and 3. 02% respectively. The twoin Fukuyama 3). The HPS process first produces quasi-iron ores are both typical high iron and low-silicon rawparticles with an average particle size of 45mm frommaterials. The quality of limestone and quicklime ismixed raw materials that don ’t contain solid fuevery good, with a higher content of CaO.Table 1 Raw material chermical compositionName .Wr.PeWcoWMDO2LOIIron Ore A .64.900.043.751.120.060.2300.0351.70lron Ore B66.360.033.020.630.1000.0301.04Manganese Ore45.018.471.130. 1414. 2300.079.05Return Fines55. 8611.30.6.111.050.990.4700.042Coke powder1. 190.215.392.520.100.012).05088.44Anthracite1.020.23 .4.662.13中国煤化工0289.91Limestone0.1654.771.180.23602238. 88Serpentione7.680.9637.351.16MHCNMHG016.13.46Quicklime0.1992. 382.250.300.020.0140.070Corresponding author: XIONG Lin; E mail: xionglin@ basteel. com4Baosteel Tchnical Research, Vol.6, No. 2, Jun.20122.2 Research methodThe test flow charts of the two kinds of sinteringSintering raw L__。 JOnce artificial IDiscmaterials mixinggranulation processes are shown in Fig. 1. The moistureof the mixture was 7. 0% when the impact of granulationtime was studied. In the HPS process, after 5 min ofSinteringRoll fuel powderin the cylinderdisc granulating, the quasi- particles roll with 50% coalpowder in the cylinder and the cylinder granulation lasts(sintering test flow chart of HPS process)for1 min. While in the MPS process, after 5 min ofSintering raw_ Once artificial_ +[ Cylindercylindar granulating, 50% coal powder is added into thematerials厂mixing granulatingcylinder to roll with the quasi-particles and then thegranulation continues for 1 minRoll fucl powderAccording to the sintering production situation andthe requirements of the chemical composition of sinter(sintering test flow chart of MPS process)ore，the ingredients of the samples are shown inTable 2 and the process parameters of sintering anFig. 1 Sintering test flow charts of HPS and MPS processesshown in Table 3.Table 2 Ingredients of sintering mixtureIronIron Manganese ReturnFuelMineralsLimestone Serpentinite QuicklimeOre AOre BOreFines Coke powder AnthraciteRatio/ mass%23. 3435.022.6223. 081.782.686.251.383.85Table 3 Process parameters of sinteringBed heightIgnition temperatureIgnition timeHolding timeIgnition suctionSintering suction/mm/C/min6401150士5015 00010000shown in Fig. 2. When the granulation time is less than8 minutes， the average particle size of the MPSmixture is significantly greater than that of the HPS3 Experimental results and discussionmixtrure and the corresponding differential pressure is3.1 Effect of granulation timelower than that of the HPS mixture. However, whenthe granulation time is more than 8 minutes， th3.1.1 Influence of granulation time on balling effectaverage particle size of the MPS mixture is less thaThe influence of granulation time on the averagethat of the HPS mixture，while the differential pressureparticle size and differential pressure of the mixture areis higher than that of the HPS mixture.6.0;5 「,.5 t: :HPS50 t: HPS.0 t45个40 t.035 t告0L2.3456789102410Granulation time , minGranulation time min(间)(bFig.2 Effecet of granulation time on average particle size and differential pressure of the mixtureprodu中国煤化工lengh of lesss than3.1.2 Effeet of granulation time on the quality of8 mi: clearly display anotablTH.C N M H GIPS process than ofsinterthe Hro pluucss. INCVCIWICICSS， wuen the granulationThe influence of granulation time on the productiontime is equal to or more than 8 minutes， theand quality of sinter is shown in Fig. 3. The MPS isperformance of MPS is significantly decreased, evenbetter than HPS in sintering speed，drop strength andlower than HPS.XIONG Lin, et al. The experimental study of the granulation proess5、2.8 [.信25息1.6爸1.5第231.4 t名22-g13.2 423Granulation time 1 minGranulation time / mina)(b79n2「HPS71 t。”, 7569 t号73豈6g265 71|66 t69654210Granulation tine 1 minc)(dFig.3 Effect of granulation time on the quality of sinteron the granulation effect and the quality of sinter wasstudied. Fig. 4 shows the effect of granulation moisture3.2 The impact of granulation moistureon the average particle size and differential pressure ofthe mixture. It can be seen that the average particle3.2. 1 Influence of granulation moisture on ballingsize of the MPS mixture is slightly bigger than that ofeffectthe HPS mixture in the same granulation moisture.In this study, the granulation time of MPS and HPSWhen the granulation moisture stays around 6. 5% orwas selected as five minutes and six minutes7.5%，the MPS mixture also holds a relatively highseparately，and the influence of granulation moisturedifferential pressure.3r- HPS+ HIPS- MPS19 tt41 t746.57.07.56.0Granulation moisture/%6)Fig.4 Effect of granulation moisture on average particle size and differential pressure of the mixtureMPS sinter has a drop strength significantly lower than3.2.2 Effect of granulation moisture on the quality ofthe H中国煤化工t the tumble indexsinterof theYH二t of the HPS sinterAs shown in Fig.5， the sintering speed andwhenCNMHG6.5% or 7%.productivity rate of MPS are significantly higher thanThough getting slightly lower than HPS in some otherthose of HPS in the same granulation moisture. Butgranulation moisture, MPS still succeeds to meet thewhen the granulation moisture is greater than 7%, threquirements on the tumble index of sintering plants.6Baosteel Technical Research, Vol.6, No.2, Jun.201224-.MPS.直221.6 t1.2 t.0 t.8 t6.06.57.7.s.646.2.0Granulation time 1 mina)(b72MPS76974g7577:666..5d)Fig.5 Effect of granulation moisture on the quality of sintergranulation moisture 7% ) were studied. The chemical3.3 Mineralogical compositioncompositions of the two kinds of sinter are shown inThe mineralogy and microstructure of the MPS sinterTable 4. Because the same ingredients and conditions( granulation time 5 minutes， granulation moistureof mixture were employed, the chemical compositions7% ) and HPS sinter ( granulation time 6 minutes,of the sinter produced by the two methods are similar.Table 4 The chemical composition of the sinter%Scheme :Wr.FeWeo，WsiorWaoWmoWA_O,WpwHPS57.915.669.400.711.210.0490.0150.451.6657.396.525.909.920.761.220.052 0.0086 0. 561.68Table 5 shows the mineral compositions of the twoThe calcium ferrite content of the MPS and HPS sintersinter samples identified by optical microscopy. It canwas 30. 25% and 28. 13% respectively and thebe seen from Table 5 that the mineral is mainlyrelationship of the calcium ferrite content in the twocomposed of calcium ferrite (CaO●Fe2O3 ), hematitekinds of sinter with the tumble index is the same. This(Fe2O3), magnetite (Fe;O,), fayaite (2FeO●SiO2/shows that MPS is better than HPS, in upholding theCaO. FeO●SiO2), silicon calcium (CaO●SiO2),formation of calcium fermrite , and thus helps to improvemagnesium ferrite ( MgO●Fe2O3) and vitreous, etc.sinter tumble index.Table 5 Sinter mineral compositionSchemeWCalcium fenteWHermatieWMageieWCactum iaie_ WNegneium fene___ w ViruWobe28. 1325. 2632.217.651.560.573.44 .1.1830. 2523.4132. 157.631.530.553.321.16stnterate，which reaches93. 69中国煤化Irate.3.4 Metallurgical propertiesThe test results in Table 6 show the matallurgicalTYHCNMHG.performance of the two kinds of sinter. The reduction(1 ) Given the granulation time of less thanand RDI properties of both the two kinds of sinter are8 minutes, the granulation of the MPS process is bettergood. In comparison with the HPS sinter, the MPSthan that of the HPS process， and the correspondingXIONG Lin, et al. The experimental study of the granulation processTable 6 Metallurgical performance of sinterMetallurgical performanceSchemeRRDI463 RDI,RDISoftening Soft meltingPmax/%1+3.150.srange/C range 心/kPaHPS89.1585.9992.752.631 1771 2661 460891949.99MPS93.6984.09 .90.52.3.041 1931 2761 4808320413.92sintering speed, productivity rate and drop strength are2] FuJ Y ,Jiang T and Zhu D Q. Sintering and pelletizingalso better. Given the granulation moisture of 7. 0%，[M]. Changsha: Central South University of TechnologyMPS exceeds HPS in performance.Press, 1996: 176-219.(2) Both MPS and HPS work in fostering the[3] Borges W and Sun Y F. HPS process application inMonlevade plant of Beierge-Mineila Black Metallurgicalformation of calcium ferrite, however, the calciumCompany[J]. Angang Technology , 2005(4) :52 -55.ferrite content in the MPS sinter is relatively high, and[4] HucQ, Zhang Y z andLi zG. A study on the fueln addition, its crystal is perfect with a satisfyingaddition in MPS process [ J]. Journal of Hebei Institutestrength and reduction property.of Technology, 2003, 25(1): 11 -15.(3) We can use MPS instead of HPS in the practicalproduction，because the MPS sinter generally hasbetter performance than the HPS sinter and is capableof meeting the production requirements.References[11 HeJ F and Huang X Y. A new technique of granulationmade from sintered mixture [ J ]. Shandong Metallurgy ，2000, 22(4): 65 -67.XIONG Lin中国煤化工MHCNMHG