直接还原法在铌提取上的应用

利用直接还原法开辟从含铌铁矿中提铌的新途径：用ＣＯ／ＣＯ２混合气体选择性还原含铌铁矿，９０％以上的铁氧化物被还原为金属铁，而铌氧化物不被还原；磁选分离还原产物，去除金属铁，得到含铌矿物。其铌品位较原矿提高了近３倍。     

含铌尾矿的直接还原研究

为开发一种新的铌铁冶炼工艺,实现综合利用国内包头白云鄂博特殊矿的铁-铌-稀土资源,进行了含铌尾矿冶炼新工艺的基础性研究。由热力学分析可知,标准状态下,C直接还原NbO的温度(1 489℃)比还原FeO的温度(705℃)高得多,所以可以通过罐式法直接还原含铌尾矿,先还原铁,分离铁与铌氧化物,使铌富集在渣中,达到铌铁分离的目的,然后再还原铌氧化物。并在此基础上,将含铌尾矿的还原效果与铁精矿的进行对比与分析,确定最佳的还原工艺和操作参数。综合各种因素,通过对3种不同装料方式罐式法还原试验的比较分析,认为最适合的还原工艺参数为:950℃饼状罐式法还原,还原时间4 h。     

包头含铌铁精矿选择性还原试验

 采用兰炭为还原剂,利用罐式选择性还原的方法处理铌铁精矿,研究不同还原条件时金属化率的变化规律,利用扫描电镜观察铌的赋存形式,利用电炉熔分脱铁的方法处理还原后的铌铁精矿,考察铌氧化物的富集程度。研究结果表明,当温度为940～970 ℃时,还原2.5 h时铌铁精矿中铁氧化物金属化率可达85%以上,在还原过程中,铌氧化物不被还原成金属铌;铌主要以含钛、铁硅酸盐形式存在于还原后团块中;熔分获得金属铁和富铌渣,富铌渣中铌氧化物是原矿的1.55倍。     

提高高炉冶炼含铌铁矿铌回收率的研究

本文论述了有关高炉中铌富集的实验室和生产实践的研究结果。已得证实,渣铁界面存在的 NbC 滞留带,阻碍了铌还原进入铁相。搅拌虽能使之有所改善,但不能有效的消除。而提高炉缸温度和活跃炉缸,以及提高炉渣碱度和维持铁水一定含硅量均有利于提高铌收率。     

喷射铌精矿在转炉钢包中直接合金化

在铌氧化物直接合金化的热力学和动力学研究的基础上,采用喷射法在100kg感应炉和10t转炉钢包中进行了铌精矿代替铌铁冶炼含铌低合金钢的试验。试验结果表明:在喷射条件下,粉剂中的Nb_2O_5可在上浮至钢液之前被迅速还原进入钢液;在喷粉过程中,(Nb_2O_5)/[Nb]接近平衡状态;在不同喷粉速度下,[Nb]的收得率主要取决于[Si],a[O]和∑FeO。控制[Si]>0.4％,∑FeO<2％,[Nb]收得率可大于80％。     

用超声波预处理含铌原料的尝试

包头富铌炉料还原冶炼时,铌的还原回收率偏低(仅50％左右)。为了提高铌的还原回收率,在炉料入炉前,我们采用简单的超声波发生器对其进行预处理,取得了明显的效果。 (一)炉料成分、试验设备及试验方法 1,炉料成分 试验用原料为富铌低铁精矿的烧结矿,其成分列于表1。还     

含铌尾矿中铁与铌的分离与回收

在热力学分析的基础上,通过碳热还原和磁选分离对白云鄂博含铌尾矿中铁的回收与铌的富集进行探索性研究。结果表明,在1 000~1 100℃下,以碳为还原剂进行焙烧可以对含铌尾矿中的铁氧化物进行选择性还原。1 100℃焙烧0.5h并经湿磨后在50mT的磁场强度下磁选,可实现铁精粉与含铌矿物的分离。磁选所得铁精粉中铁品位为84.82%,铁收得率为81.95%,磁选尾矿中铌品位为1.98%,铌回收率达到95%以上。     

含铌铁水直接冶炼含铌微合金钢的试验

 含铌铁水通过脱碳保铌探索作为合金化元素回收铁水中铌并直接冶炼为含铌微合金钢的方法。试验在真空碳管炉内进行,铁水温度为1 500 ℃,氧化剂为Fe2O3,真空度为10 Pa,分别进行有SiO2-CaO-Al2O3系造渣剂、无渣真空氧化冶炼研究。结果表明：在无渣条件下,加入Fe2O3铁水中硅、铌和碳同时氧化,不能脱碳保铌;加入造渣剂时,造渣剂的碱度越低,铁水中的硅氧化量越低,碳氧化量越高,碳质量分数最低下降到0.032%,铌质量分数最低值从0.09%下降到0.082%;碱度越高,铁水中硅氧化量越高,铌的氧化量也越高;真空氧化冶炼能够促进碳氧化,减少硅的氧化,抑止铌氧化。在50 kg级真空感应电炉内成功进行了回收铁水中铌直接冶炼为含铌钢试验,为回收含铌铁水中的铌提供新方法,也为工业化直接冶炼含铌钢提供试验依据。     

包头铌铁矿冶炼实验研究

针对包头矿高铁低铌的特点提出了选择性还原-熔分-铌铁冶炼的处理方案,并对方案的三个关键步骤进行了实验研究。结果表明,熔分阶段铌回收率在95%以上,冶炼阶段铌回收率在85%以上,全流程铌回收率>80%,铌磷Nb/P>15。本流程完全可综合回收包头矿中的铌、铁、锰等元素。     

含铌钢用铌铁矿 微合金化试验

用铌铁矿代替铌铁合金,在电炉冶炼20MnSiNb钢时进行微合金化,在冶炼操作工艺只作小的调整情况下,铌的回收率可达70～90％,比用铌铁合金费用降低近20％。本试验尚属初步探索,还有一些技术工艺问题,有待今后研究解决。     

Separation of Nb from Nb‐bearing iron ore by selective reduction

A new approach for extraction of Nb from Nb‐bearing complex iron ore, found in North‐West China, is proposed. Selective reduction of the complex iron oxides by CO‐CO₂ gas mixture was conducted, and the reduced metallic Fe was magnetically separated from the Nb‐bearing gangue residue. The Nb‐rich product was leached with HCl to remove P. A highly concentrated Nb‐bearing product with Nb/Fe = 6, Nb/P = 12 might be possible to make commercial grade of 60–65 % Nb ferroniobium.     

高铝铁矿和高锰铁矿共还原行为的研究

高铝铁矿和高锰铁矿是两种储量丰富但又极难分选的铁矿资源,实现铁、锰、铝的高效综合利用具有重要意义.本文研究了这两种铁矿石工艺矿物学,考查了单矿种及两者的混合矿种的直接还原行为及还原过程中的矿物组成演变,揭示了相应的还原机理.结果表明:高铝铁矿难还原,其机理为经还原后仅部分铁氧化物转化为金属铁,其余的铁与铝、硅矿物形成难还原的铁橄榄石和铁尖晶石;高锰铁矿易还原,其中的铁氧化物大部分被还原成金属铁,锰氧化物与铝、硅矿物结合形成锰尖晶石和锰橄榄石,促进了铁氧化物的还原.而且在相同还原条件下,高锰铁矿球团金属化率比高铝铁矿高30个百分点,前者还原性明显优于后者.两种矿进行共还原,当高锰铁矿配比达到60%时,球团金属化率就可大于90%.锰氧化物的存在对高铝铁矿石中铁氧化物的还原具有显著的促进作用.     

Influence of Na2 CO3 as Additive on Direct Reduction of Boron-bearing Magnetite Concentrate

Boron-bearing magnetite concentrate is typically characterized by low grade of iron and boron (wTFe=51%-54%,wB2 O3=6%-8%),as well as the close intergrowth of ascharite phase and magnetite phase.A promising technology was proposed to separate iron and boron by coupling the direct reduction of iron oxides and Na activation of boron minerals together.The influence of Na2 CO3 as additive on the direct reduction of boron-bearing magnetite was studied by chemical analysis,kinetic analysis,XRD analysis and SEM analysis.The results showed that the ad-dition of Na2 CO3 not only activated boron minerals,but also reduced the activation energy of the reaction and pro-moted the reduction of iron oxides.Besides,the addition of Na2 CO3 changed the composition and melting point of non-ferrous phase,and then promoted the growth and aggregation of iron grains,which was conducive to the subse-quent magnetic separation.Thus,the coupling of the two processes is advantageous.     

钾长石对CO还原铁氧化物过程还原膨胀性的影响

摘要：包钢巴润矿具有粒度细、品位高、价格低廉、适合球团生产等特点,但该矿是一种典型的高碱负荷磁铁矿,其中碱金属含量较高。以揭示含钾脉石对铁氧化物还原膨胀性的影响为出发点,采用分阶段还原法,通过在线检测的方法研究了不同天然钾长石添加量对CO的Fe2O3→Fe3O4,Fe3O4→FeO以及FeO→Fe分阶段还原过程试样的线膨胀率进行了检测,并对各阶段还原产物的物相组成和显微结构采用XRD和SEM进行了分析。结果表明,试样在氧化焙烧过程中,天然钾长石中的钾长石熔化后形成玻璃相,SiO2以石英的形式析出。试样中天然钾长石质量分数从0增加到12%,在Fe2O3→Fe3O4还原阶段,其线性膨胀率从2.19%下降到2.11%,试样在焙烧过程中钾长石形成的渣相对Fe2O3还原膨胀性起到抑制作用;在Fe3O4→FeO还原阶段,其线性膨胀率从-0.51%增加到0.46%,钾长石引起Fe3O4晶格畸变,造成Fe3O4还原膨胀加剧;在FeO→Fe还原阶段,其线性膨胀率从-6.26%增加到-1.68%,天然钾长石中的SiO2与FeO结合形成铁橄榄石对FeO还原过程的铁相收缩起到抑制作用。因此,钾长石主要对CO还原Fe2O3的第Ⅰ和第Ⅱ阶段作用明显,SiO2主要对还原第Ⅲ阶段产生影响。     

高钛渣碳热还原—浮选法提取Ti_2CO

通过高温碳热还原分别将高钛渣中的钛和铁还原至富钛相物质Ti2CO和金属铁,并使其中的熔渣相MOx不被还原,然后选用油酸作为捕收剂对Ti2CO/MOx模拟混合原料开展了浮选研究。结果表明,采用该工艺从还原产物中得到了产率79.88%、Ti2CO回收率87.74%的浮选效果。     

Microstructure Characteristic and Phase Evolution of Refractory Siderite Ore during Sodium-carbonate-added Catalyzing Carbothermic Reduction

Thermodynamic analysis of refractory siderite ore during carbothermic reduction was conducted.Microstructure characteristics and phase transformation of siderite ore during sodium-carbonate-added catalyzing carbothermic reduction were investigated.X-ray diffraction(XRD),scanning electron microscopy and energy-dispersive analysis of X-rays were used to characterize the reduced samples.Results indicate that the solid reaction between FeO and SiO_2 is inevitable during carbothermic reduction and the formation of fayalite is the main hindrance to the rapid reduction of siderite.The phase transformation of present siderite ore can be described as:siderite-magnetite-metallic iron,complying with the formation of abundant fayalite.Improving the reduction temperature(≤1 050 ℃)and duration is helpful for the formation and aggregation of metallic iron.The iron particle size in the reduced ore was below 20μm,and fayalite was abundant in the absence of sodium carbonate.With 5% Na_2CO_3 addition,the iron particle size in the reduced ore was generally above 50 μm,and the diffraction intensity associated with metallic iron in the XRD pattern increased.The Na_2O formed from the dissociation of Na_2CO_3 can catalyze the carbothermic reduction of the siderite.This catalytic activity may be mainly caused by an increase in the reducing reaction activity of FeO.     

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%.     

Enrichment of phosphorus in reduced iron during coal based reduction of high phosphorus-containing oolitic hematite ore

With the objective of phosphorus enrichment in the metallic iron during coal based reduction, high phosphorus oolitic hematite ore was reduced in the presence of coal with the coal/ore molar ratio (C/O, the molar ratio of fixed carbon in coal to oxygen in iron oxides of ore) varying from 1·0 to 2·5 at temperatures ranging from 1473 to 1548 K. The metallic iron was beneficiated from reduction products by magnetic separation. The results showed that the enrichment of phosphorus in the metallic iron improved with increasing temperature and C/O molar ratio. The phosphorus content and the phosphorus enrichment could reach 2·5 and 77·5%, respectively, with a C/O molar ratio of 2·5 at 1548 K and after 60 min reduction. The high phosphorus-containing metallic iron so obtained could then be converted to steel and high phosphorus steelmaking slag that can be used as a phosphate fertiliser. Kinetic analysis demonstrated that the process of phosphorus enrichment in the metallic iron could be divided into two stages, early and late, described by phase boundary controlled reaction and diffusion controlled, respectively. At the early stage, the apparent activation energy and pre-exponential factor of phosphorus enrichment decreased from 182·12 kJ mol^?1 and 9509·06 min^?1 to 132·60 kJ mol^?1 and 395·44 min^?1, respectively, when the C/O molar ratio was increased from 1·0 to 2·5. At the later stage, the apparent activation energy and pre-exponential factor were 245·87 kJ mol^?1 and 172?818·99 min^?1 at a C/O molar ratio of 1·0, respectively, whilst those were reduced to 210·73 kJ mol^?1 and 13?930·28 min^?1 at a C/O molar ratio of 2·5.     

Direct Reduction Experiment on Iron-Bearing Waste Slag

 A lot of iron-bearing slags were produced, and whose grade is much more than that of industrial iron ore grade. Chemical analysis and phase identification shows that the iron-bearing slag is amorphous, has fayalite main phase, iron grade is 36. 10%, and is difficult to recover iron from the slag. Thermodynamic calculation indicates that CO cannot reduce fayalite at high temperature and carbon direct reduction can be effective. Moreover, the reaction begins at 770 ℃ and the temperature can be reduced down to 500℃ when CaO is added. On this basis, a method is put forward to making direct enrichment of iron by taking carbon contained pellets to realize the rapid reduction of fayalite, and the direct reduction process were studied in this paper. Experiments show that xC/xO should be less than 1. 5 for the need of reduction and carburization, and CaO and Al2O3 can spur the reduction of fayalite. On conditions that xC/xO is 1. 2, metallization rate can be 77% when temperature is 1250 ℃ and only carbon is added, and metallization rate can be 74% when temperature is 1200 ℃ and only CaO is added. Moreover the addition of Al2O3 can get a higher metallization rate (10% or so) than usual as R is between 0. 4 and 1. 0. Under the optimized condition of R equals to 0. 6, temperature of 1250 ℃, slag melting point of 1320 ℃, and time of 30 min, the metallization rate can reach 88. 43%.     

铁矿粉配比对铁焦性能影响的试验研究

 高反应性铁焦是一种能够改善高炉内铁矿石还原反应效率,大幅削减CO2发生量,提高弱黏结煤和低品位矿石使用率的新型高炉原料。系统地研究了铁矿粉种类及配比对铁焦灰分、硫分、相对密度、气孔率、机械强度、热性质、铁矿粉的还原程度等性能的影响。试验结果表明,随着铁矿粉配比的增加,铁焦的硫分有所增加,灰分线性增加,真、假相对密度均提高,总、显气孔率均降低,抗碎强度和耐磨强度均降低,反应性提高、反应后强度降低,金属铁含量增加,加矿和鄂矿的还原程度提高、澳矿有所降低。当铁矿粉配比为15%时,加矿或鄂矿铁焦中金属铁（MFe）的质量分数为6%~9%,铁矿粉中的氧化铁有55%~70%还原成铁。