A novel process for the recovery of iron,titanium,and vanadium from vanadium-bearing titanomagnetite:sodium modification–direct reduction coupled process

A sodium modification–direct reduction coupled process was proposed for the simultaneous extraction of V and Fe from vanadium- bearing titanomagnetite. The sodium oxidation of vanadium oxides to water-soluble sodium vanadate and the transformation of iron oxides to metallic iron were accomplished in a single-step high-temperature process. The increase in roasting temperature favors the reduction of iron oxides but disfavors the oxidation of vanadium oxides. The recoveries of vanadium, iron, and titanium reached 84.52%, 89.37%, and 95.59%, respectively. Moreover, the acid decomposition efficiency of titanium slag reached 96.45%. Compared with traditional processes, the novel process provides several advantages, including a shorter flow, a lower energy consumption, and a higher utilization efficiency of vanadium-bearing titanomagnetite resources. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Recovery of vanadium from vanadium slag by composite roasting with CaO/MgO and leaching

A novel process of composite roasting with CaO/MgO and subsequent acid leaching was proposed to improve the recovery rate of vanadium from Linz–Donawiz(LD)converter vanadium slag.The effects of the MgO/(CaO+MgO)molar ratio and the roasting and leaching parameters on the recovery of vanadium were studied.The results showed that the leaching efficiency of vanadium decreased from 88%to 81%when CaO was replaced completely by MgO;however,it could be improved by roasting with the composite of CaO/MgO.The maximum vanadium leaching efficiency of 94%was achieved under the optimum MgO/(CaO+MgO)mole ratio of 0.5:1.The results from X-ray diffractometry(XRD)and scanning electron microscopy with energy-dispersive X-ray spectroscopy(SEM−EDS)confirm that the formation rate of acid-soluble vanadates can be enhanced during roasting with the composite of CaO/MgO and that the leaching kinetics can be accelerated owing to the suppression of calcium sulfate precipitation.

Extraction of vanadium from molten vanadium bearing slag by oxidation with pure oxygen in the presence of CaO

A novel process of vanadium extraction from vanadium slag in its molten state was conducted at the laboratory scale by oxidation with pure oxygen in the presence of CaO. The effect of mass ratio of CaO to V2O5 on the recovery of vanadium was studied. The sintered samples were leached by H2SO4 solution and characterized by XRD, XPS, SEM and EDS techniques. Compared with the roasting process, the energy saving effect of the proposed process was also discussed. The results showed that vanadium-rich phases were formed and vanadium mainly existed in the forms of CaV2O5 and Ca2V2O7. The formation mechanism of calcium vanadates in the molten vanadium bearing slag was explained. The XRD and XPS results implied that there was a limit to the oxidation reaction of V(IV) to V(V) under the high temperatures even though oxygen-supply was sufficient. An increase in the CaO content led to an increase in the formation of Ca2V2O7. About 90%of the vanadium recovery was obtained under optimal experiment conditions (mass ratio of CaO to V2O5 of 0.6, particle size 120 to 150μm, leaching temperature 90 °C, leaching time 2 h, H2SO4 concentration 20%, liquid to solid ratio 5:1 mL/g, stirring speed 500 r/min). The energy of 1.85×106 kJ could be saved in every 1000 kg of vanadium bearing slag using the proposed process from the theoretical calculation results. Recovery of vanadium from the molten vanadium bearing slag and utilisation of its heat energy are important not only for saving metal resources, but also for energy saving and emission reduction.

Separation and Recovery of Phosphorus from P-bearing Steelmaking Slag

In order to recycle the phosphorus from P-bearing steelmaking slag, the influences of magnetic field inten- sities, slag particle sizes and slag compositions were investigated by magnetic separation experiments. SiO2, A1203 and TiO2 melting modification of converter slag was made respectively and phosphorus-rich phase was extracted by magnetic separation. The results show that MgO, MnO, Na2 0 and CaF2 have little effect on the phosphorus recovery, whereas the addition of SiO2, Al2 03, and TiO2 has great effect on phosphorus enrichment in slag and magnetic separation. With adding the reagent of SiO2 Al2 03 and TiO2, recycled non-magnetic substances are increased obviously and P2 05 content in nowmagnetic substances and phosphorus recovery rate are also increased. The phosphorus recovery rates of modified slag No. 8 （SiO2 modification）, slag No. 10 （AI2 03 modification） and slag No. 11 （TiO2 modification） are 84.75 %, 82.16 % and 74.46 %, respectively. Then, most of phosphorus was recycled.

Recovery of vanadium from vanadium slag by composite additive roasting-acid leaching process

To minimize the vanadium content in the vanadium extraction tailings, composite additive roasting with (CaO + MgO) and subsequent acid leaching process was carried out dealing with vanadium-bearing converter slag. The effect of additive with different MgO/(CaO + MgO) molar ratios on the roasting and leaching behaviours of vanadium slag was investigated, and the optimum process conditions were obtained. The results show that in the roasting experiment, under the conditions of roasting temperature of 850 ℃ and roasting time of 2 h, the main kinds of vanadate transformed from Ca_(2)V_(2)O_(7) to Ca_(5)Mg_(4)V_(6)O_(2)4 and then to Mg_(2)V_(2)O_(7) with the increase in the MgO/(CaO + MgO) molar ratio. In the leaching experiment, under the conditions of particle size less than 75 μm, leaching temperature of 50 ℃, pH of 2.5, liquid–solid ratio of 20:1, and MgO/(CaO + MgO) molar ratio of 1:3, the leaching efficiency of vanadium is increased by about 5%, but the substitution of MgO for most or all of CaO will significantly reduce the leaching efficiency of vanadium. Furthermore, the leaching efficiency of impurities (P and Cr) can also be decreased by a composite addictive (CaO + MgO) roasting process. The X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, and X-ray photoelectron spectroscopy of the original vanadium slag and solid products of both roasting and leaching processes were also evaluated.

钒磷铁渣在酸性氧化体系中的浸钒工艺研究

以钒磷铁渣为研究对象,采用盐酸-过硫酸钠为浸出体系,研究酸浸提钒工艺技术。探索浸出温度、浸出时间、盐酸浓度、过硫酸钠用量、样品粒度和液固比等对钒浸出的影响。结果表明:在浸出温度95℃、浸出时间22 h、盐酸浓度25%、过硫酸钠用量6.4 g/g、样品粒度200目、液固比10∶1、搅拌速度400 r/min的较佳条件下,钒浸出率达到87.36%。

钠化焙烧提钒工艺过滤系统的优化

针对钒渣钠化焙烧提钒工艺过滤系统钒回收率低、运行成本高等问题,结合产线现有流程装备,对球磨浸出和板框过滤系统进行了升级改造。为避免在输送过程中杂物堵塞、提高料浆输送和过滤洗涤效率,球磨浸出系统加装滚筒筛去除浆液中大颗粒物料及杂物,使用水力旋流器将胶体及细小颗粒分离。研究了回转窑出料量对水力旋流器设备匹配的影响,经过优化调整试验,沿过滤带运动的垂直方向两侧各布置3台水力旋流器,出口直径分别为25 mm和35 mm。板框过滤机被真空带式过滤器替换后,设备维护费用降低83.65%,同时研究了工艺参数对过滤效率和钒收率的影响,在真空带15 mm料层厚度和梯度洗涤最优工艺条件下,尾渣中钒平均含量从0.1%降至0.087%,钒收率提高0.53%,实现了浆料过滤过程高效率运行。

铁矾渣熔化-烟化过程中铅元素的挥发性质研究

采用火法中的熔化-烟化法回收铁钒渣中的有色金属铅,并通过热力学计算在还原焙烧过程中金属铅所需的反应条件。探究回收铅过程中不同工艺参数对铅回收率的影响,并确定回收的较优工艺条件。用扫描电子显微镜、能谱仪和X射线衍射技术对收集到烟尘的形貌、成分和结构进行表征。结果表明:铁钒渣中的铅物相在熔化-烟化过程中,当温度高于1 000℃时,PbS最先开始挥发进入烟尘中;烟尘中回收的铅主要以PbO和PbS形式富集,其中PbO是单质铅挥发后被氧化的产物,呈四棱柱形状;在较优反应温度1 242℃下铅的回收率达99.70%。

含钛高炉渣浸出液中钛的协同萃取分离工艺及机理研究

钒钛磁铁矿在高炉冶炼过程中产生大量的冶炼渣,该冶炼渣的钛含量达20%~30%,对钒钛磁铁矿或冶炼渣中的钛资源进行资源化利用一直是重要的研究课题。本文借鉴浸出-萃取提钛工艺,针对已有的萃取体系萃取平衡时间长、钛萃取率低、设备易腐蚀、水相和有机相分相困难等问题,先将机械活化后钒钛磁铁矿高炉渣进行盐酸浸出,然后采用磷酸三丁酯(TBP)与二(2-乙基己基)磷酸(P204)组成的协同萃取体系(稀释剂为磺化煤油)对浸出液中的钛进行萃取试验。试验考察了萃取剂总浓度、萃取温度、萃取相比(O/A)、萃取剂TBP和P204的物质的量的比、氯离子浓度等因素对钛萃取率的影响,同时采用斜率法对萃取机理进行了初步的探究,得到如下结论:在萃取剂物质的量比TBP∶P204=1∶4、萃取时间20 min、萃取温度30℃、萃取相比(O/A)1∶1、氯离子浓度8 mol/L等较佳萃取条件下,钛萃取率可达到98%以上;斜率法研究萃取机理表明,萃合物组成可能为(TiOCl_(2))(HA)_(2)(HB)_(2),其萃取化学反应式可以改写为:TiO^(2+)+2HA+2HB+2Cl-→(TiOCl_(2))(HA)_(2)(HB)_(2)。

自还原钒渣压块的直接合金化行为

提出了一种钒渣在线还原直接合金化冶炼含钒钢的工艺,并通过热力学分析及实验研究,阐明了钒渣中氧化物的选择性还原趋势、钒回收率的影响因素以及合金化过程的反应机理.结果表明:在合金化20 min后,钢液中钒的质量分数快速上升至0.56%;随着合金化温度从1520℃升高到1600℃,钒的回收率从70.23%增至84.54%,并且在温度1600℃、压块碱度0.5、合金化时间25 min的最佳实验条件下,钒的回收率最高可达90.04%.此外,为保证钒渣快速合金化和钒的高回收率,可将钒渣与还原剂混合制成较小尺寸的钒渣压块,以实现在工业生产中提高钒回收率的目的.

含钒转炉钢渣中钒的提取与回收

针对攀钢目前含钒铁水的工艺流程和含钒转炉钢渣中V2O5 含量,提出了从含钒钢渣提钒的新的技术思路和工艺,并对新工艺的关键环节———含钒钢渣冶炼和高钒铁水提钒进行了试验研究。结果表明:采用矿热炉冶炼含钒钢渣,生铁中钒的质量分数达7 45%,对含钒生铁进行提钒,钒渣中V2O5 的质量分数达35 06%,实现了钒资源的有效提取和综合回收。

用碳热还原法从含钒钢渣回收含钒生铁

实验研究表明对于含钒2.65%钢渣,钒元素主要分布在RO相和Ca3SiO5相中;调节渣中(CaO/SiO2)=2,含V2O53.4%的合成渣,熔化缓冷后,钒主要固溶于Ca3SiO5相中;对于V2O5含量在4.7%～7.0%之间的钢渣,钒是以CaV2O6还是Fe-Nn-V-O固溶体形式存在主要取决于渣中铁氧化物的含量.在钒含量较低的钢渣中,由于含钒相的晶粒较小,很难将钒从其它组分中分离出来,但在1550～1600℃条件下,用碳热还原法可以有效地回收钢渣中的钒,得到被碳饱和的钒铁合金,利用渣在冷却过程中自动粉化现象,很容易实现渣和合金的分离.

半钢炼钢条件下的溅渣护炉技术

介绍了攀钢 12 0t转炉溅渣护炉研究中所进行的钒钛钢渣性质、钒钛钢渣成分选择、造渣工艺优化、降低终渣TFe含量。

Al2O3对含钒钢渣中钒富集行为的影响

为能有效富集含钒钢渣中的钒,针对Al_2O_3作用于钒富集过程的行为进行了相关热力学研究.结果表明,用Al_2O_3高温改性后的含钒钢渣在缓冷过程中,固溶有钒和磷的硅酸二钙相会先期析出.在1623 K附近,该矿物与熔渣中Al_2O_3反应生成富钒矿物—钒磷酸钙(固溶有Ca和Si组分)和钙铝黄长石.平衡体系中的硅酸二钙会随渣中Al_2O_3的增加而减少直至消失,剩下钒磷酸钙和钙铝黄长石与熔渣平衡共存.其中,钙铝黄长石的生成趋势更为占优,如渣中Al_2O_3足量,已生成的钒磷酸钙中的部分Ca和Si组分,还会继续与渣中Al_2O_3结合,再次生成钙铝黄长石,使磷酸钙中的钒品位进一步提高,这也是渣中钒和磷结合后含有较少杂质而生成高品位富钒相的最本质原因.

多膛炉焙烧转炉钒渣工艺研究

对转炉钒渣进行了物理化学分析，并根据转炉钒渣和多膛炉的特点，在实验室进行了系统的实验。根据小试结果，对多膛炉的焙烧工艺进行了改进，使多膛炉焙烧转炉钒渣的转化率达86．6％，浸出残渣的TV下降到1．2％左右．

含钒钢渣添加SiO_2后的钒富集相与钒富集行为

为含钒钢渣设计富钒相,使钢渣中的钒主要富集于所设计的富钒相中.中国马钢的钢渣和瑞典SSAB的钢渣是本研究使用的样本.尽管炉渣的来源和化学组成各不相同,但是可以发现其矿物组成大致相似,而且无法仅仅通过对炉渣的热处理来实现钒的富集.本文根据钒和炉渣的基本物理化学性质设计了两种适合于作为富钒相的矿物:溶有w(S i)<3%的3CaO.V2O5和3CaO.P2O5的固溶体以及另外一种w(S i)约10%的由3CaO.2S iO2,3CaO.V2O5和3CaO.P2O5的组成的矿物.通过添加S iO2对炉渣的化学成分进行调整,在炉渣中得到了所设计的富钒相,且炉渣中超过2/3的钒富集于其中.本研究为钢渣中的钒提出了一种新的回收利用途径.

含钒钢渣中负组元钙的净化与回收

含钒钢渣产自钒钛磁铁矿的炼钢过程,是很有价值的冶金二次资源,可作为提钒的重要原料。然而,含钒钢渣中负组元钙含量极高,高含量的钙会极大地降低提钒的指标、增加提钒的成本,因此对负组元钙进行净化与回收,是必要的提钒预处理手段。基于含钒钢渣中负组元钙的特点,分析了其净化与回收的研究进展,指出了存在的问题,提出了相应的建议:摇床重选净化率不高,并会损失一定的正组元钒,且净化后的钙无法回收,今后可尝试处理能力大的重选设备,并强化重选过程,提高重选精度与选择性;高温焙烧成本高、污染重,基本不具推广应用价值;一些其它技术,具有借鉴作用,能否移植尚不明确,有待进一步完善和发展;氯铵浸出法选择性好,净化率高,不会造成钒的损失,同时可将净化后的钙富集于浸出液中进而实现沉钙回收,是一种有前途的方法;氯铵浸出法优势明显,其回收、循环方面需进一步研究完善。

钙对钒渣提钒的影响

分析了攀钢钒渣的物理、化学性质,研究了钒渣焙烧、浸出过程的工艺参数对钒回收率的影响规律,优化工艺条件用于钒氧化物生产。

高硅高钙钒渣钠化焙烧工艺的优化研究

针对某钒厂钒渣精粉中SiO_2、CaO含量增加的情况,在实验室以现有工艺参数进行了钠化焙烧,在获得实验室试验基准参数条件下进行了正交和单因素优化试验,较全面考察了焙烧高温区间、碱比、全钒含量和保温时间对钒渣钒焙烧转化率的影响,同时以优化参数进行了验证试验。结果表明,以钒硅比V_2O_5/Si0_2=0.8,钒钙比为V_2O_5/CaO=4.6的高硅高钙钒渣精粉进行钠化焙烧,最优焙烧工艺为:焙烧高温区间:550～820℃,碱比:1.8～2.0;全钒含量:4.8%～5.2%;保温时间:120～140 min,可以使钒焙烧转化率达到85%以上。

攀钢炼钢系统部分技术热点透视

通过试验结果和计算分析，对攀钢炼钢系统技术热点进行了剖析，并提出了进一步理顺工艺的措施和建议。