白云石强化含氟铁精矿球团的研究

 研究了配加白云石粉提高MgO含量对含氟铁精矿球团质量的影响。试验结果表明：提高球团矿中MgO含量对生球质量的影响不大。当球团MgO含量从0.83%增加到2.0%时,成品球抗压强度显著提高,强度从3555 N/个提高到了5050 N/个。但由于白云石的分解产生CO2增加了球团的孔隙率,使得提高球团矿中MgO含量会降低预热球抗压强度,通过延长预热时间来完成Fe3O4的氧化即可以提高预热球抗压强度也可以提高成品球抗压强度。在较高的焙烧温度下,MgO大多赋存于铁相中稳定了磁铁矿和含镁矿物的晶格,这些矿物与Fe2O3、铁酸钙等互连和紧密胶结,相互熔蚀,有利于球团抗压强度的提高。     

MgO含量对高铝铁矿球团强度的影响

以高铝赤铁矿为主原料、菱镁矿为含镁添加剂制备镁质球团，探究MgO含量对高铝铁矿球团强度的影响。结果表明，生球落下强度随着MgO含量的增加会小幅下降，但仍然可以满足生产要求；焙烧球抗压强度随着MgO含量的增加呈现先降低再增高后又降低的趋势，当MgO质量分数约为1.80%时有助于降低MgO对焙烧球强度的不利影响；菱镁矿直接进入球团会大幅降低焙烧球抗压强度，需要经煅烧处理后才能用于镁质球团生产。采用FactSage热力学软件计算了MgO含量在不同焙烧温度下对球团液相生成量的影响规律，结合球团微观结构观察、孔隙度检测等多种手段，探究了MgO含量影响球团强度的作用机理。通过球团焙烧热力学、微观结构分析结果可知，焙烧球强度与焙烧时液相生成量密切相关，液相生成量在MgO质量分数为1.80%附近达到峰值，适量的液相加快了结晶质点的扩散，填充了球团中的孔隙，有利于焙烧球强度的提升。在适量的范围内添加镁质熔剂有助于降低其对高铝铁矿球团焙烧球强度的不利影响，该结论可为高铝镁质球团研究提供重要参考。     

含镁添加剂用于铁矿球团的试验研究

应用含镁添加剂,并配以膨润土,对铁矿球团进行了实验室试验。试验研究表明:添加轻烧白云石和镁砂对提高生球质量能起到一定的促进作用,而镁橄榄石的影响较小;随着添加剂用量的增加,三种球团矿的抗压强度均显著降低,其下降幅度由大到小依次为镁砂球团、轻烧白云石球团和镁橄榄石球团;适当提高焙烧温度,延长焙烧时间,有利于提高球团的抗压强度。另外,冶金性能研究也表明:随着添加剂用量的增加,球团还原度和软熔性能有一定提高,低温还原粉化和还原膨胀性能显著改善。     

MgO质量分数对氧化球团性能的影响

 为了改善澳洲某磁铁矿氧化球团的冶金性能,研究了MgO质量分数对其质量的影响。研究结果表明,随着MgO质量分数的提高,生球落下强度和爆裂温度提高,MgO质量分数对生球抗压强度影响较小。随着MgO质量分数提高,预热球团和焙烧球团抗压强度降低,还原度有所改善;提高MgO质量分数可以有效抑制球团的低温还原粉化和球团的还原膨胀,软化开始温度、软化结束温度和滴落温度均有所提高,软熔性能得以改善。这主要是由于提高MgO质量分数,渣相中铁酸镁和钙镁橄榄石质量分数升高,在还原过程中Mg2+与Fe2+发生晶格取代,生成FeO与MgO的固溶体,具有稳定晶格的作用,从而抑制还原膨胀和低温还原粉化。     

高效镁质添加剂用于铁矿球团的试验研究

高效镁质添加剂是一种由高活性氧化镁粉和植物蛋白胶体构成的球团复合粘结剂。针对该高效镁质添加剂完全取代膨润土进行了造球、预热、焙烧、抗压强度及成品球团的冶金性能试验研究。结果表明:配加高效镁质添加剂可降低球团还原膨胀率1.54%~4.34%,初始软熔温度提高25℃,滴落温度提高250℃以上,其使用比例为3%。     

球团配加镁质熔剂及新型皂土试验

为生产含MgO的镁质球团用来替代烧结矿中MgO,确保高炉造渣所需的适宜的MgO质量分数,考察了在球团生产中添加一种新型球团黏结剂(新型皂土)和一种氧化镁质熔剂(镁石粉)时,对造球焙烧及球团矿冶金性能的影响。试验结果表明,镁质球团生球落下强度有所提高,350℃时未发生爆裂。配加新型皂土可提高球团品位,降低Si O2质量分数。镁质球团的低温还原粉化指标和体积膨胀率指标均有所改善。而且,软化温度升高,软化温度区间变窄,有利于软熔带由高炉上部往下部移动,改善高炉透气性。在保证综合入炉铁料MgO质量分数不变的条件下,当烧结矿自然带入的MgO质量分数为1.2%时,球团矿中的MgO质量分数大于1.90%,可满足高炉要求。     

高镁铁精矿制备球团试验研究

目前,镁质球团制备主要是添加镁质熔剂,对高镁精矿直接制备镁质球团研究较少。以国外某高镁铁精粉为原料,系统研究了造球参数、预热参数及焙烧参数对球团性能的影响,并进行了投笼工业试验。结果表明,在膨润土用量1.2%,生球水分8.0%,造球时间15min的条件下,生球落下强度4.2次/(0.5m),抗压强度18 N/P,爆裂温度425℃;在预热温度1050℃,预热时间15min,焙烧温度1250℃,焙烧时间15 min的条件下,预热球团抗压强度524N/P,焙烧球团抗压强度2589N/P;成品球团的全铁品位63.35%,MgO含量1.70%,有害元素含量低,冶金性能优良,是一种优质的高炉炉料。     

低硅含镁球团矿抗压强度及冶金性能

提高入炉原料品位降低硅含量,改善冶金性能是高炉精料的主要方向。研究了低硅球团矿的还原膨胀率及MgO对低硅球团矿抗压强度和冶金性能的影响。研究结果显示,低硅球团矿虽然具有品位高,脉石含量低等优点,但随着SiO2含量的降低球团矿还原膨胀率恶化,影响高炉冶炼。低硅球团配加含镁添加剂可以有效控制还原膨胀率,同时改善球团矿的还原度和熔滴性能。球团矿SiO2的质量分数低于2%时,还原膨胀率在60%以上;当MgO的质量分数提高到2.15%以上时,还原膨胀率能降到20%以下,但随着MgO含量的增加低硅球团矿抗压强度下降,需要提高焙烧温度,才能形成稳定的铁酸镁,改善抗压强度。MgO的质量分数为2.15%时,焙烧温度要提高到1 270℃,MgO的质量分数超过2.8%以上时,焙烧温度需要提高到1 300℃。     

不同含镁添加剂对球团矿工艺参数及质量的影响

 MgO对高铁低硅烧结中烧结矿的质量有不利影响,但其可以改善球团矿的冶金性能。因此,不在烧结矿而在球团矿中添加MgO,可在改善烧结矿质量的同时提高球团矿的冶金性能。不同的含镁熔剂对球团工艺参数和性能影响不同。通过试验研究了在高铁低硅条件下,白云石、蛇纹石、硼泥和镁质添加剂等4种含镁添加剂对球团造球,焙烧工艺及对球团矿物化性能和冶金性能的影响。试验结果显示,镁质添加剂对提高球团矿MgO含量、控制低硅球团矿还原膨胀率、改善球团矿还原度和熔滴性效果最好。     

高镁球团改善炉料结构理化性能的实验研究

实验发现,添加MgO能很好地改善球团矿的高温冶金性能。随着MgO的增加,球团矿的高温还原度和软熔滴落性能得到改善,且低温还原粉化率和膨胀率均有明显下降。但与此同时,当球团矿镁含量上升时,其抗压强度、落下强度下降得比较明显。因此在高炉中配加含MgO球团时,需要综合考虑高MgO球团的理化性能对炉料结构影响。该结果实际运用于某厂的球团生产,为其高炉炉料中添加高镁球团提供了理论基础和技术支持。     

Utilization of High Sulfur Raw Materials in Iron Ore Pellets

Pyrite cinder and high sulfur magnetite were used as raw materials to produce iron ore pellets. Good qualities of green balls and fired pellets were obtained from the feed comprising 50% pyrite cinder and 50% high sulfur magnetite concentrate at a small scale. Small-scale tests were proven by pilot-scale tests. The high grade fired pellets, assaying 63.22% Fe, were analyzed, and the compressive strength of fired pellets was over 2500 N/pellet. The fired pellets possessed excellent metallurgical performances, such as reducibility index higher than 67%, reduction swelling index lower than 15% and low temperature reduction degradation index (+ 3.15 mm) higher than 1%, which can be used as the burden for blast furnace.     

SG带式焙烧机镁质球团矿的生产应用

为满足高炉对镁质熔剂球团矿的质量要求,SG带式焙烧机进行轻烧镁粉、轻烧白云石及二者混合(按一定配比)添加的3种镁质熔剂添加方案工业试验。试验结果表明,添加轻烧白云石可以提高生球强度。采用轻烧镁粉和轻烧白云石按1∶3的添加方案,当该方案球团矿MgO质量分数为1.58%时,平均抗压强度为2 245 N/个,还原度为75.36%,还原膨胀率为14.37%及低温还原粉化率(RDI_+3.15)为96.79%,其综合冶金性能优于其他方案球团矿,并符合高炉对镁质熔剂球团矿的抗压强度和冶金性能要求。     

MgO、F、碱金属对球团矿相组织的影响

因为白云鄂博铁精矿球团含有较多的碱金属和氟,从而产生异常还原膨胀,而添加MgO可以有效抑制其还原膨胀,但是MgO的添加势必影响球团的矿相组成.目前研究多注重MgO、F、碱金属中某一单因素对球团物相的影响,而对3者共同作用于球团物相的影响还缺乏深入研究.采用正交试验的方法研究了(K2O+Na2O)、CaF2和MgO对赤铁...     

转炉用溅渣镁球造渣技术

针对转炉炉渣MgO含量偏低的现象,对转炉使用溅渣镁球代替轻烧白云石造渣技术,合理控制溅渣镁球的加入量,达到降低终渣FeO、提高渣中MgO来迅速降低炉渣过热度等目的,从而可以缩短溅渣时间,提高溅渣层的抗侵蚀能力,最大限度发挥溅渣护炉效果,延长补炉间隔时间,节约耐火材料,提高生产作业率,并降低炼钢的冶炼成本。     

优化配矿强化西澳超细粒磁铁精矿球团焙烧研究

进行了西澳超细粒磁铁精矿分别配加国产磁铁精矿和巴西赤铁精矿制备氧化球团矿的实验研究.结果表明,以100%西澳超细磁铁精矿为原料制备氧化球团矿时,球团预热及焙烧性能较差,在预热温度为1050℃、预热时间20 min及焙烧温度1300℃、焙烧时间40 min的条件下,预热球团和焙烧球团矿抗压强度分别为每个502和2313 N.西澳超细粒磁铁精矿配加40%国产磁铁精矿或20%巴西赤铁精矿时,球团适宜预热温度由1050℃分别降低到950和975℃,适宜的焙烧温度由1300℃分别降低到1250和1280℃;而且焙烧球团矿的抗压强度分别提高到每个2746 N和每个2630 N.焙烧球团矿的微观结构研究表明：配加国产磁铁精矿后,焙烧球团矿中Fe₂O₃晶粒发育优良,晶粒间互联程度提高,晶粒粗大,孔隙率低,固结更加紧密.配加20%巴西赤铁精矿时,焙烧球团矿中Fe₂O₃晶粒基本连接成片,Fe₂O₃晶体发育良好.优化配矿是改善西澳超细粒磁铁精矿球团矿预热及焙烧性能的有效途径.     

Effect of the firing temperature and the added MgO on the reduction swelling index of the pellet with low SiO2 content

The use of pellet with low SiO₂ content in blast furnace (BF) will reduce the slag amount as well as fuel rate and increase the productivity. In this paper, the effect of the firing temperature and the added MgO on the reduction swelling index (RSI) and the compressive strength of the reduced pellet with low SiO₂ content was investigated, and the microstructure of the fired and reduced pellets was analysed by means of the electron microscopy. It was found that the decrease of SiO₂ content will raise the RSI and reduce the compressive strength of reduced pellet. When the SiO₂ content of pellet is 4.8%, the RSI is 16.5% and compressive strength of reduced pellet is 423 N/P. When the SiO₂ content is 2.8 and 1.8% fired at 1280°C, the RSI of the reduced pellet will increase to 34.5 and 55.8% and the compressive strength is reduced to less than 200 and 80 N/P. However, if some MgO was added, the RSI and the compressive strength of the reduced pellet could be improved significantly. When pellet’s MgO content was over 1.7% and SiO₂ content was 2.8% or MgO content was 2.5% and SiO₂ content was 1.8% fired at 1280°C, the RSI of the two pellets could drop to less than 20% and the compressive strength could increase to more than 300 N/P. Then, the technical index of pellet will meet the requirement of the charging in large BF. The added MgO pellet with low SiO₂ content have been used in 5500?m³ BF in Shougang Jingtang Corporation and delivered sustainable improvement of cost reduction.     

MgO对高碱度高铝烧结矿的影响

 随着钢铁企业高铝铁矿粉使用比例的提高,带来了高炉炉渣黏度增大、渣铁分离困难等一系列问题。采用烧结杯试验,研究了MgO含量增加对高碱度高铝烧结矿经济技术指标、冷强度和冶金性能的影响,采用Nova400 NanoSEM型场发射扫描电子显微镜分析了烧结矿微观结构。试验结果表明,高碱度高铝烧结矿中MgO质量分数从1.72%提高到2.49%时,垂直烧结速度降低4.38 mm/min,利用系数降低0.51 t/(m2·h),低温还原粉化指数增加6.7%;当烧结矿中MgO质量分数为2.11%时,转鼓指数和还原度最高,分别达到61.93%和86.39%;Mg2+主要固溶在磁铁矿晶格中并替代Fe2+,替代的质量分数最高达3.64%,生成的含镁磁铁矿抑制烧结矿降温过程中由Fe₃O₄→Fe₂O₃氧化过程的相变,减少了二次赤铁矿的生成,有利于改善烧结矿的低温还原粉化性能。研究结果可以为改善高碱度高铝烧结矿性能和提高炉渣流动性提供理论指导和参考依据。     

Chemistry,microstructure, and reduction characteristics of dolomite-fluxed magnetite pellets

The addition of dolomite to iron ore pellets improves high temperature reduction properties, primarily by increasing their softening point and reducibility. This study was made to ascertain the compositional ranges within which dolomite fluxed magnetite pellets show such an improvement over good acid pellets. A variety of compositions with MgO levels from 1 to 2 wt pct and CaO/SiO₂ ratios of 0.6 to 1.8 were prepared using Hibbing magnetic concentrate. These compositions were balled and then pot-grate fired to various temperatures. Petrographic examination and electron microprobe analyses were used to characterize the phase assemblages. Reduction characteristics were also evaluated. As evidenced by the following petrographically observed relationships, the CaO/SiO₂ ratio (c/S) was found to be the controlling factor for pellet microstructure: a) The low c/S (< 0.8) pellets were predominantly oxide-bonded, b) the intermediate c/S (0.8 to 1.3) pellets were slag- and oxide-bonded, and c) the high C/S (> 1.3) pellets were mostly calcium ferrite-bonded. Intermediate c/S compositions contain more magnesioferrite than do either low or high basicity compositions. Pellets must be fired to a high enough temperature to generate sufficient liquid for ion transport but not so high as to cause pellets to stick together. Well-fired pellets with a c/S of 1.3 or less performed adequately in low temperature degradation tests. Pellets with a c/S of 0.8 or greater displayed satisfactory swelling behavior. Therefore, we determined that pellets within a c/S range of 0.8 to 1.3 are technically acceptable. Pellets containing 1.5 wt pct MgO had the best reduction characteristics, but all fluxed compositions reduced faster and more completely than did acid pellets. Increasing MgO content up to 2.0 pct increased the softening temperature by 165‡C over acid pellets. On the basis of pellet test results and taking into consideration the auxiliary influence of economic and operating considerations, we determined the optimum composition of dolomite fluxed Hibbing pellets to be 1.5 pct MgO and a C/S of 0.8.