农作物废弃物-铁精矿球团性能研究

采用农作物废弃物自制炭粉与铁精矿粉制备含碳球团,对含碳球团的造球特性进行了试验研究。结果表明：含碳球团的强度与造球物料的粒度、水分含量、膨润土加入量、焙烧还原温度等有关。物料粒度细、膨润土含量增加能提高球团的强度,适宜的碳氧比为1.0,水分和黏结剂配比分别为8.0%和6.5%;随着焙烧还原温度的提高,球团强度相应提高,当温度达到1 200 ℃时,随着金属铁快速还原与连晶的形成,球团落下强度为15次/个,抗压强度为1 650 N/个,能满足高炉入炉料的要求。     

白云鄂博铁精矿内配碳球团还原动力学研究

为降低CO2排放量,发展以H2为还原剂的炼铁生产方式势在必行.针对富氢气固还原工艺中存在着气体利用率低和还原供热不足等问题,利用热重法研究了温度、碳氧比、煤粉粒度对白云鄂博铁精矿含碳球团还原速度的影响.结果表明,在碳氧摩尔比为1.1时,还原温度越高,煤粉越小,含碳球团还原速度越大.基于碳气化反应、气相扩散和界面反应的含碳球团还原速度方程能较好地处理本研究的数据.在850℃下,由未反应核模型得出气体内扩散活化能和界面反应活化能分别为87.3 kJ/mol和306 kJ/mol,还原温度越高,扩散阻力越大,化学反应阻力越小.在950℃下,还原反应过程速度由气体内扩散控制.     

白云鄂博铁精矿含碳球团直接还原实验研究

对于白云鄂博铁精矿进行了内配碳直接还原的研究,通过正交实验考察C/O、焙烧温度和H2/CO 3个因素对金属化率的影响.得出最优的实验方案:C/O为1.1,焙烧温度为950℃,H2/CO为3:2.在最优实验方案下,球团金属化率可达89.24%,还原度为91.96%.     

含碳球团强度及金属化率的影响因素

在1000～1200 ℃条件下研究了不同的矿粉粒度、配碳比、粘结剂、还原温度等对含碳球团强度及金属化率的影响.结果表明,以水玻璃为粘结剂的含碳球团具有较好的强度和金属化率.     

高磷铁矿碳热还原同步脱磷的实验研究

为探索高磷铁矿的有效利用途径,对高磷鲕状赤铁矿进行碳热还原同步脱磷实验研究,在含碳球团中添加CaO和Na2C O3作为脱磷剂,采用D T A-T G- M S综合热分析、X R D、SE M、E DS等方法分别对高磷鲕状赤铁矿的碳热还原过程以及还原产物进行分析. 结果表明,添加适量的CaO和Na2C O3可以显著提高脱磷率;在1 573 K、Na2C O3添加量为2 %、含碳球团碱度为1 .2的条件下,高磷鲕状赤铁矿能够被快速还原成含磷0 .09 %、含碳4 .6 %的碳饱和铁,脱磷率达到95 %;生铁中碳过饱和后以片状石墨的形态析出,生铁中的磷以夹杂物Ca3（P O4）2和Na2Ca4（P O4）2SiO4的形式存在     

农作物废弃物含碳球团还原行为研究

将农作物废弃物炭化产品与铁精矿粉制成含碳球团,进行直接还原试验研究。试验结果表明,含碳球团在1 200~1 300 ℃范围内,铁氧化物能在15~20 min内迅速被还原,高温保持时间以15~20 min为宜;随温度的升高球团的还原度逐渐增大,球团还原适宜温度为1 200 ℃;球团的失重率和还原度随球团配炭比的增加呈上升趋势,较合理的球团碳氧比为0.9;生物炭较高的含碳量和适当的挥发分含量均有利于球团的还原;含碳球团在空气中能快速还原,但存在部分再氧化现象。     

提高尘泥含碳球团烘干后强度的实验研究

针对尘泥含碳球团烘干后强度降低进行实验研究,通过改变原料配比、粘结剂种类、球团烘干制度和造球方法提高含碳球团烘干后强度.结果表明:使用钙基含碳球团粘结剂配合复式法造球,钙基含碳球团粘结剂加入量为原料总质量的1.8％,造球时间30 min,球团烘干风温180℃,风速1.0m/s.该实验条件下烘干后球团平均抗压强度为152...     

不同种类生物质对工业硅球团性能影响的研究

实验以洗精煤、木炭粉、石油焦、微硅粉为原料,并与改性后的稻壳、玉米秸秆、小麦秸秆或水稻秸秆混合,制备生物质工业硅球团.研究了不同种类生物质含量对湿球抗压强度、干球抗压强度、抗碎率、热强度与孔隙率的影响,并与市购的R粘结剂制备的球团性能进行比较.实验结果表明:当以水稻秸秆为生物质时,制备的生物质球团湿球抗压强度为1 215.6 N,干球抗压强度为5 230.8 N,抗碎率为80.36%,热强度为94.40%,孔隙率为24.39%.与R制备的球团相比,湿球抗压强度提高74.47%,干球抗压强度降低25.11%,抗碎率降低13.32%,热强度提高39.15%,孔隙率提高9.20%,在工业硅生产中可以考虑与木质素磺酸钠、淀粉等粘结剂复合使用.     

转炉细灰对转底炉直接还原含碳球团性能的影响

将转炉细灰用于转底炉直接还原含碳球团造球试验.结果表明,转炉细灰对提高球团抗压强度和落下强度有一定效果,但要想获得理想的球团强度,须达到一定的添加量;添加一定量的转炉细灰,可以提高含碳球团的还原速率和金属化球团的TFe、MFe含量;用转炉细灰调节渣相碱度,在还原温度为1450 ℃时可实现渣铁良好分离,其脱硫效果好于同碱度下的石灰石.     

印尼红土镍矿粉成球机理及其利用

为探讨红土矿粉造球并直接入炉的可行性,通过对红土矿粉粒度、化学成分的分析,采用造球的方法使其成为具有一定形状的球团,实验研究不同粘接剂的成球性能,并模拟回转窑温度和还原性气氛对球团进行预还原实验和高温强度测试。结果表明:红土镍矿粉配入3%的新型粘接剂进行造球,成球率达到70%以上,球团干燥后落下强度达到30次以上。在还原性气氛、1 100℃预还原焙烧后球团都能保持颗粒的完整性,无破裂粘接现象,抗压强度为472 N个,完全可以作为冶炼原料进入电炉进行生产,达到了工业生产入炉要求。     

不同骨料级配透水混凝土的性能研究及其孔隙识别

依据体积堆积理论采用5~10、10~15、15~20 mm单粒级的碎石骨料设计和配制孔隙率分别为15%、20%、25%的透水混凝土,利用相关数学模型探究实测孔隙率与透水混凝土性能相关性,通过平面孔隙二值化识别透水混凝土内部孔隙结构特征。结果表明:透水混凝土的实测孔隙率能达到设计孔隙率的90%以上,与表观密度呈现良好的线性关系,与透水系数和抗压强度均呈现良好的幂函数关系。设计孔隙率的变化对骨料粒径较小的透水混凝土的透水性能影响较大,较小的骨料粒径有利于增加透水混凝土的28 d抗压强度,较大的骨料粒径有利于增加透水混凝土的透水系数。设计孔隙率与骨料粒径的增大均能使透水混凝土内部孔隙等效直径增大,降低孔隙曲折度,改变骨料级配,但骨料粒径的影响作用更为明显,二者的作用机理不同。     

Influence of sulfur content in raw materials on oxidized pellets

The influence of sulfur content in raw materials on oxidized pellets was studied. The results show that most sulfur exists in the form of elementary sulfur in pyrite cinder, and over 95% sulfur is removed in producing pyrite cinder oxidized pellets. The compressive strength of fired pellets drops from 3 186 N to 2 405 N when the ratio of pyrite cinder increases from 40% to 70% under the conditions of preheating at 900 °C for 9 min and firing at 1 230 °C for 15 min. The porosity and microstructures of fired pellets prove that the higher ratio of pyrite cinder is given, and the more holes and cracks are achieved, leading to the better reducibility index (RI) and reduction swelling index (RSI), and the lower compressive strength of fired pellets and the worse reduction degradation index (RDI).     

Effect of coal gangue with different kaolin contents on compressive strength and pore size of blended cement paste

The effects of activated coal gangue on compressive strength, porosity and pore size distribution of hardened cement pastes were investigated. Activated coal gangue with two different kaolin contents, one higher and one lower, were used to partially replace Portland cement at 0%, 10%, and 30% by weight. The water to binder ratio（w/b） of 0.5 was used for all the blended cement paste mixes. Experimental results indicate that the blended cement of activated coal gangue mortar with higher kaolin mineral content has a higher compressive strength than that with lower kaolin mineral content. The porosity and pore size of blended cement mortar were significantly affected by the replacement of activated coal gangue.     

透水性砼配合比正交试验方法

基于混凝土强度和透水性要求,根据现有实验室条件,运用相似原理和正交实验原理对C15透水性混凝土的配合比进行试验方法研究.采用3因素3水平均值相似正交法提出了研究水灰比、骨灰比、骨料粒径对混凝土空隙率、透水率和抗压强度影响的试验方法,根据透水性混凝土性能要求确定了试配强度、水泥用量、水灰比、粗集料用量.最后提出根据所建立的正交试验表,利用极差分析、方差分析和线性回归分析确定最优配合比和各因素显著性的方法.研究表明,该方法同样适合于分析不同因素、基于不同性质和目的的透水性混凝土配合比的设计.     

骨料对透水混凝土性能的影响

试验研究了骨料品种、骨料粒径对透水混凝土主要性能的影响。试验结果表明：在相同骨料粒径的情况下,由碎石骨料配置的透水混凝土总孔隙率和透水系数明显大于卵石骨料配置的透水混凝土,碎石的强度变化幅度比卵石的变化幅度明显;随着骨料粒径的增大两种骨料配置的透水混凝土的孔隙率、透水系数均有所增大,在同一配合比情况下,随着骨料粒径的增大透水混凝土的强度呈非线性变化,且存在最佳粒径尺寸。     

生物质型焦的生产工艺及性能研究

研究了用生物质作粘结剂并采用干法冷压成型工艺将烟煤和无烟煤冷压成型,然后炭化制取生物质型焦的工艺,分析了生物质添加量、烟煤种类和配入量以及成型压强对型焦的抗压强度、光学组织、气孔结构、微观强度和以应性的影响,结果表明,随着生物质添加量的增大,型煤的抗压强度随之增大,但型焦的抗压强度降低;配入肥煤和焦煤所产型焦的光学各向异性强,大气孔少,孔隙率低、反应性人氏、反应后强度高;烟煤与无烟煤之间成焦后为非熔融粘结,导致型焦反应后强度明显降低,生物质、烟煤、无烟煤三者的配比以１８：５５：２７为最佳。     

Pore Size Distribution of High Performance Metakaolin Concrete

The Compressive strength, porosity and pore size distribution of high performance metakaolin (MK) concrete were investigated. Concretes containing 0,5%,10% and 20% metakaolin were prepared at a water/cementitious material ratio (W/C) of 0.30.In parallel, concrete mixtures with the replacement of cement by 20% fly ash or 5 and 10% silica fume were prepared for comparison.The specimens were cured in water at 27℃ for 3 to 90 days .The results show that at the early age of curing(3 days and 7 days),metakaolin re-placements increase the compressine strength ,but silica fume replacement slightly reduces the compressine strength.At the age of and after 28 days ,the compressive strength of the concrete with metakaolin and silica fume replace-ment increases.A strong reduction in the total porosity and average pore diameter were observed in the conctete with MK 20% and 10% in the first 7 days.     

烧胀助剂对高强粉煤灰陶粒性能的影响

在粉煤灰中掺入不同比例的助胀剂和助熔剂,利用可控武电热炉对高强粉煤灰烧胀陶粒进行了试验研究。结果表明:在焙烧温度为1250～1280℃,焙烧时间为25～30 min时,随着助胀剂掺量的增加,粉煤灰烧胀陶粒的体积密度、表观密度和24 h吸水率逐渐减小;助熔剂掺入后可显著提高陶粒的颗粒强度,降低其吸水率,改善陶粒内部的孔形结构;易烧系数与粉煤灰陶粒的孔隙率、颗粒强度呈较好的线性关系。     

程潮铁精矿球团质量影响因素分析

以程潮铁精矿为原料进行造球试验,考察铁精矿粒度、膨润土种类及配比、造球水分和造球时间对球团质量的影响。结果表明,这几种因素对生球的落下强度、抗压强度和爆裂温度均有很大的影响;当程潮铁精矿中-0．074 m m粒级含量为85．10％、膨润土A配比为1．5％、造球水分为8％、造球时间为12 m in时,能得到生球落下强度为9．8次/（0．5m）、抗压强度为20．5N/个、生球爆裂温度为467℃的优质球团矿。     

Coal and gas outburst prevention using new high water content cement slurry for injection into the coal seam

As coal and gas outburst is one of the most serious mine disasters, it is very important to at least control it if not prevent it from occurring. Injecting cement slurry or grouting into the coal seam can strengthen the seam, increase its rigidity coefficient(f), and reduce the volumetric expansion due to gas energy release.This paper reports the results of laboratory experiments on cement-based high water content slurry having different water-cement ratios(W/C) to be used for coal injection. The results show that as the W/C increases, the mobility of the slurry and its setting time increase. The compressive strength and rupture strength, however, are reduced. Furthermore, high W/C grout shows early strength after 7 days, which can be 80% of its 14-day compressive strength. To achieve rapid setting and early strength, the addition of Na_2SiO_3has proven to give the best result, when the concentration of the additive is 3%. The initial and final setting times are 13 and 21 min shorter than samples without Na_2SiO_3, while the compressive strength is more than double. As a retarder, the initial setting time can be extended to 83 min when tartaric acid of 0.4% concentration is added. Through the orthogonal experiment, the optimum recipe of the new high water content slurry has been determined to be: W/C = 2, tartaric acid = 0.2%, Na_2SiO_3= 3%, and12% bentonite. Reinforcement by injection simulation experiments show that the grouting radius of the new slurry mix is 250 mm when the applied grouting pressure is 60 k Pa, 7-day rupture strength and compressive strength are 5.2 and 6.4 MPa, respectively, and are 37% and 88% higher than ordinary cement grout. It can be concluded that the newly developed slurry mix is more effective than the ordinary mix for reinforcing coal and controlling gas outburst.