Reduction of Pyrite Cinder Pellets Mixed with Coal Powder

Direct reduction of pyrite cinder in a rotary hearth furnace(RHF)was studied under the condition of laboratory simulation.Effects of reduction temperature,reduction time,molar ratio of carbon to oxygen,and CaO addition on metallization rate as well as compressive strength of the pellets after reduction were discussed.The results showed that the metallization rate and compressive strength were 93.9% and 2160Nper pellet respectively under the conditions of the reduction temperature of 1200℃,the reduction time of 16min,and the molar ratio of carbon to oxygen(xC/xO)of 1.0;adding 2.5% CaO was beneficial to sulfur enrichment in slag phase of pellet,and metallization rate increased slightly while compressive strength decreased.     

赤泥预还原球团的熔分

为了实现赤泥资源高附加值化综合利用,通过高温模拟试验对赤泥含碳球团还原焙烧-熔分过程进行研究。将赤泥含碳球团在1 200℃下进行还原焙烧,并结合相图分析,向粉碎后的焙烧球团中添加一定比例的CaO、Al_2O_3进行调质和熔分。结果表明,赤泥含碳球团在1 200℃下还原12min后金属化率可达91.3%,还原效果良好;在1 450℃下进行还原熔分,可实现渣铁的有效分离,金属铁收得率可达到90%以上,所得铁水质量符合炼钢要求;熔分渣中w(TFe)可降至0.5%以下,渣中主要物相为12CaO·7Al_2O_3、CaTiO_3和2CaO·Al_2O_3·SiO_2,通过熔点性能测试试验,熔化性能符合钢液脱硫条件。     

铜渣煤基直接还原过程中的铁物相转变

摘要：采用直接还原工艺回收铜冶炼渣中的铁，对不同温度下铁物相的转化以及金属铁颗粒的长大规律进行分析。通过对铜渣进行配料造球 煤基直接还原焙烧 弱磁选处理，得到了直接还原铁精矿指标随时间及温度的变化。结果表明，在焙烧温度1300℃，焙烧时间30min的条件下得到了TFe质量分数为91.55％、金属化率为92.99％及回收率为82.99％的铁精矿。对不同还原温度下铁精矿分析表明：1050、1100、1150℃均生成了金属铁，但还原度及TFe含量较低。1200℃时发现有Fe2C5及SiC相的生成，形成的CaSiO3·FeSiO3液相影响了还原过程。1250℃时生成了Fe3C，但Fe2SiO4会与CaO形成低熔点矿物。1300℃时精矿中含有大量金属铁，但也形成了低熔点化合物，增加了后续处理的难度。金属铁颗粒首先出现在矿物颗粒失氧而产生的裂纹及孔洞的边缘，金属铁小颗粒被大颗粒吸收并聚结长大，金属铁经过斑点状 蠕虫状 仙人掌状的转变最后形成致密的金属铁层。     

Reduction Characteristics and Kinetics of Bayanobo Complex Iron Ore Carbon Bearing Pellets

 The kinetics of isothermal reduction of the carbon bearing pellets, which were mainly composed of Bayanobo complex iron ore and pulverized coal, was investigated by thermogravimetry at the temperature of 1273-1673 K. The effects of xC/xO and the atmospheres on the extent of reduction also were investigated. The results indicate that the fractional reaction increased proportionally with temperature increasing and heating temperature is the significant influence factor to the reaction of carbon bearing pellets. The optimum xC/xO is 1. 2 and the effect of atmosphere on the reduction of iron oxides is almost negligible. The results can be interpreted that the reaction was initially controlled by a mixed controlled mechanism of carbon gasification and interface chemical reaction, and in the later stage, interface chemical reaction became the rate-controlling step. Apparent activation energy values of reduction at different levels of fractional reaction were calculated. Before F (fraction of reaction)=0. 5, the apparent activation energy ranges from 66. 39 to 75. 64 kJ/mol, while after F=0. 5, the apparent activation energy is 80. 98 to 85. 37 kJ/mol.     

Nuggets Production by Direct Reduction of High Iron Red Mud

 In order to utilize the iron resource effectively in red mud, a laboratory experiment based on the orthogonal method was carried out. Nuggets were gotten by directly reducing the carbon-bearing pellets of red mud and coal. The results showed that the strongest influencing factor is temperature, and the separation between liquid iron and slag is thoroughly. The nuggets can be gotten when the pellets, in which xC/xO is 1. 6 and the basicity is 1. 0, were maintained in 30 min at 1400 ℃. The nuggets have a high TFe content which is higher than that in the hot metal produced in BF. It also has a low content of Si and Mn, but a high content of S and P. The main compositions of the slag are amorphous phase mainly containing SiO2 and unreduced Fe2SiO4. Of course, a little reduced iron retains in it.     

镍渣煤基直接还原过程中金属铁颗粒的生长特性

 镍渣煤基直接还原可有效利用其中的二次资源。定量描述不同条件下镍渣煤基直接还原过程中金属铁颗粒的生长特性及规律,为后续磨矿及磁选工艺的制定提供理论支撑,以此来达到镍渣资源化利用的目的。采用扫描电镜获得还原产物中金属铁颗粒的微观形貌,通过Image-Pro Plus图像分析软件对扫描图片进行金属铁颗粒尺寸测量统计,并对还原后样品进行金属化率检测。结果表明,煤基直接还原技术能够有效还原镍渣中的铁氧化物,产物的金属化率呈先增长后稳定的变化趋势,温度为1 250 ℃、时间为60 min时,金属化率最终可达91.89%;随着还原时间的延长及还原温度的升高,镍渣还原产物中金属铁颗粒的聚集和生长加快,颗粒的平均直径逐渐变大;还原温度为1 250 ℃,还原时间为60 min时,金属铁颗粒的平均直径可增长到10.3 μm。     

Direct Reduction of High-phosphorus Oolitic Hematite Ore Based on Biomass Pyrolysis

Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases(CO,H_2,and CH_4),tar,and char was conducted to investigate the effects of reduction temperature,iron ore-biomass mass ratio,and reduction time on the metallization rate.In addition,the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation.It was determined that the metallization rate of the hematite ore could reach 99.35% at iron ore-biomass mass ratio of 1∶0.6,reduction temperature of 1 100℃,and reduction time of 55 min.The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature.The particle size of direct reduced iron(DRI) has a great influence on the quality of the iron concentrate during magnetic separation.The separation degree of slag and iron was improved by the addition of 15 mass% sodium carbonate.DRI with iron grade of 89.11%,iron recovery rate of 83.47%,and phosphorus content of 0.28% can be obtained when ore fines with particle size of-10 μm account for 78.15%.     

红土镍矿选择性还原-熔分制备镍铁合金

以硅镁型红土镍矿为原料,采用金属化焙烧-熔分工艺,通过正交试验制备金属化球团,将所得金属化球团在1500℃条件下熔融分离30 min提取镍铁合金,考察影响因素对实验结果的影响.结果表明:在选择性还原制备金属化球团过程中,对金属化率的影响程度从大到小的因素依次是C/O摩尔比、焙烧温度、焙烧时间和碱度;实验可获得镍品位19%的镍铁合金;在碱度为0.8-1.2范围内,S和P分配比随着碱度的升高而增大.利用X射线衍射和扫描电镜对金属化球团及熔融分离出的渣进行微观分析,发现加入的石灰石与复杂矿相反应可释放出简单镍氧化物和铁氧化物,促进还原反应的进行,当石灰石不足时,少量铁以Fe3+的形式存在于铁金属化率70%的金属化球团中.      

转底炉直接还原铜渣回收铁、锌技术

采用转底炉直接还原工艺,将铜渣含碳球团在高温条件下直接还原得到金属化球团和高品位氧化锌粉尘,再通过熔分或磨矿磁选方式将铁回收,得到的铁产品可作为冶炼含铜钢的原料.转底炉中试结果表明:采用"转底炉直接还原—燃气熔分"流程处理铜渣,可获得TFe品位94%以上、铁回收率93%以上的熔分铁水;采用"转底炉直接还原—磨矿磁选"流程处理铜渣,可获得TFe品位90%以上、铁回收率85%以上的金属铁粉;采用两种流程处理铜渣,均可获得锌品位60.02%的ZnO粉尘.结果表明,经过转底炉直接还原,铜渣中的铁橄榄石Fe_2SiO_4和磁铁矿Fe_3O_4相转变为含有金属铁Fe、二氧化硅SiO_2和少量辉石相Ca(Fe,Mg)Si_2O_6的金属化球团,具备通过磨选或熔分进行进一步富集的条件.     

低配碳含碳球团组分对低温熔分性能的影响

根据低配碳直接还原—低温熔分工艺制备粒铁的技术思想,考察了渣相成分对熔分开始时间及熔分后铁收得率的影响.试验结果表明,随着CaO添加量的增加,球团熔分开始时间先减小后增加.当CaO添加量为2.0％时,熔分开始时间最短.n(C)/n(O)为0.8时,渣相熔点较低,流动性较好,有利于渣铁分离.综合考虑熔分时间、铁收得率及能耗等,实验室条件下的最佳工艺参数为n(C)/n(O) =0.8,CaO添加量为2.0％,反应时间40 min(熔分开始时间30 min+熔分时间10 min).该条件下铁收得率约为85％,铁粒中铁含量约为94％,金属化率达95％以上,可作为优质的电炉炼钢原料.     

含铁硅酸盐矿物重构与选择性回收

回收含铁硅酸盐矿物是实现鞍山式贫磁铁矿再选中矿综合利用的关键之一,但这一回收过程应有选择性:一段磁选尾渣TFe仅为3.92%,不予以回收;而二段尾渣TFe为34.51%,可将其返回直接还原配料,予以间接回收。还原温度1150℃、还原时间45 min、石灰石用量16%以及还原煤用量12%时,闭路实验获得的最优粉末铁TFe为92.69%,εFe为91.17%。含铁硅酸盐中铁元素被还原为单质铁,硅元素最终重构为硅灰石。      

Pulverized Coal Combustion of Nitrogen Free Blast Furnace

 The efficiency of coal combustion is an important factor for the blast furnace process. The influence of low xO/xC on coal combustion performance under nitrogen free blast furnace condition was researched through the self-developed pulverized coal burning device. The results show that the coal combustion rate reduces with xO/xC decreasing, and the combustion rate of bituminous coal is higher than that of anthracite. The coal combustion rate ascends with the rise of volatile matter, but when volatile matter of pulverized coal is more than 18%, the combustion rates will not increase correspondingly. Small amount of CaCO3 and CO2 additions can promote coal combustion, and the effect of CaCO3 is more apparent, which can increase the pulverized coal combustion rate by 15%-18% or so.     

温度对高磷鲕状赤铁矿含碳球团直接还原影响

对高磷鲕状赤铁矿含碳球团直接还原进行了研究。结果表明,1100℃以下时,提高温度可以显著提高球团金属化率;1100℃以上时,继续提高温度对球团金属化率影响不大。球团金属化率越高,磁选精矿铁品位越高。还原温度不仅显著影响球团的金属化率,还影响金属铁相的长大及磁选效果。因此,控制适宜的温度对高磷鲕状赤铁矿含碳球团直接还原至关重要。     

循环钢渣与铜渣搭配利用的碳热还原

 通过理论分析,提出了铜渣与钢渣搭配利用的新工艺,并通过试验考察了含碳球团的还原和熔分情况,探讨了该工艺的可行性。铜渣和钢渣互为熔剂,促进了相互的还原过程,碱度为2.0时最有利于磷的还原,1 400 ℃还原30 min时磷的气化脱除率约为75%;碱度为1.0时最有利于铁氧化物的还原,1 200 ℃还原20 min时试样的金属化率达到92%。铜渣与钢渣的质量之比高于1.32时可以实现渣、铁分离,碱度为1.0时粒铁的收得率超过90%,磷在粒铁中的分布率接近45%。     

高磷鲕状赤铁矿铁磷分离试验研究

对高磷鲕状赤铁矿进行了显微结构研究,采用添加脱磷剂直接还原焙烧-磁选工艺进行了铁和磷分离试验,研究了焙烧温度、内配碳量、添加剂配比对铁、磷分离主要技术指标的影响。结果表明:磷主要以磷灰石的形态嵌布在鲕状结构中,部分与赤铁矿形成环状间层,层间的厚度变化范围在3~15μm之间;在焙烧温度1 000℃、内配碳量6%、添加剂配比10%的优化工艺条件下,通过球磨-磁选试验可得到含铁品位大于85%、含磷量在0.15%~0.20%之间的优质还原铁粉和含磷为3.5%~4%的富磷渣。     

镍渣直接还原磁选提铁试验

 通过试验对镍渣和煤粉制备含碳球团的直接还原和磁选进行了研究,考察了不同温度、碳氧比、碱度等参数随时间的金属化率变化情况,以及不同磨矿细度下的磁选结果。结果表明：碳氧比为1.2,碱度为0.5的镍渣含碳球团,在1300℃下直接还原20min后可以获得98.34%的金属化率,在该条件下还原后所得金属化球团磨矿时间从10min增加到90min,粒度小于0.074mm所占比例从46.9%增加到95.6%,磁选后精矿TFe质量分数从78.82%降低到74.01%,而磁选产率与铁回收率则分别从51.77%和79.02%增加到70.92%和89.80%。实验室结果表明,镍渣通过含碳球团直接还原磁选的方式利用其中的铁资源在工艺上是可行的。     

贵州鲕状赤铁矿的氢气还原行为

在800～1100℃范围内、H2体积分数为99.99％的气氛条件下,采用气基直接还原工艺对贵州鲕状赤铁矿进行了恒温还原研究,使用X射线衍射仪和光学显微镜对还原产物进行了表征,通过阿伦尼乌斯公式计算了还原反应的表观活化能,并采用未反应核模型判断了还原反应的限制性环节.结果表明:当还原温度为1100℃,还原时间为150 min,二元碱度为1.0时,可以获得金属化率为91.15％的直接还原产物,原矿中加入CaO促进了FeAl2O4和Fe2SiO4的还原,是还原产物金属化率提高的主要原因.动力学结果表明:原矿在900～1 100℃的还原过程中受气体内扩散控制,其表观活化能为18.95 kJ/mol,并且在典型气体内扩散范围内.     

CaO对海滨钛磁铁矿精矿直接还原?磁选工艺中还原气氛的影响

以铁品位为58.58%、TiO₂品位为12.04%的海滨钛磁铁矿精矿为试样,进行煤基直接还原–磁选试验。从反应产生的CO和CO₂气体组成、总反应的气化速率、CO分压值、金属化率、矿物组成等角度进行分析,查明了CaO在海滨钛磁铁矿精矿直接还原?磁选工艺中的作用机理。研究结果表明,CaO可以提高还原剂的气化速率,促进钛磁铁矿的还原,增加CO₂气体的产生量,从而降低CO分压值。同时发现CaO可以参与固固反应,降低含钛矿物中的FeO含量,也有利于钛、铁组分的迁移和富集,促进金属铁颗粒的聚集长大。因此,添加CaO有利于通过磨矿?磁选促进钛铁分离与回收。      

Carbothermic Reduction of Zinc and Iron Oxides in Electric Arc Furnace Dust

The reduction of zinc and iron oxides from electric arc furnace dust(EAFD)by carbon was investigated at temperatures between 800and 1 300℃.The analytic technique employed includes chemical analysis,X-ray fluorescence spectroscopy(XRF),X-ray powder diffraction(XRD),scanning electron microscopy(SEM)equipped with X-ray energy dispersive spectrometry(EDS),and thermodynamic database FactSage 6.2.It was found that the reduction of zinc and iron oxides depends largely on Boudouad reaction.At 900 ℃,zinc exists in tested samples as ZnO,which is reduced in the temperature range of 1 000-1 100℃.At 1 100℃,99.11% of the zinc is evaporated.The metallization ratio of Fe is 79.19% at 1 300℃,as the content of Fe2+ is still 9.40%.A higher temperature is thus required for a higher reduction degree of Fe oxides by solid or gaseous carbon.     

高硅铁废渣直接还原铁晶粒形成与长大

 冶金工业每年会产生大量的高硅铁废渣,铜渣作为一种典型的高硅铁废渣,目前主要以露天堆积方式处理,为了提取铜渣中有价元素,并进行资源化利用,以某厂铜渣为例进行煤基直接还原试验,采用XRD衍射、扫描电镜等分析手段,探究铜渣在直接还原过程中不同阶段以及加入形核剂条件下铁晶粒的形成、长大及分布规律。结果表明,还原时间为30 min时,金属化率最高为78.40%,铁晶粒生长情况最为良好,铁元素分布最集中;还原过程中加入磁铁矿能明显提高金属化率,有利于铁晶粒的生长,当磁铁矿配比为20%时,金属化率最高,为87.59%;磁铁矿作为形核剂加入可降低形核位垒,促进铁晶粒的长大与铁元素的集中分布。