Phase equilibria relations in the V_(2)O_(5)-rich part of the Fe_(2)O_(3-)TiO_(2)-V_(2)O_(5) system at 1200℃ related to converter vanadium-bearing slag

The efficient recycling of vanadium from converter vanadium-bearing slag is highly significant for sustainable development and circular economy.The key to developing novel processes and improving traditional routes lies in the thermodynamic data.In this study,the equilibrium phase relations for the Fe_(2)O_(3)-TiO_(2)-V_(2)O_(5)system at 1200℃in air were investigated using a high-temperature equilibrium-quenching technique,followed by analysis using scanning electron microscopy-energy dispersive X-ray spectrometer and X-ray photoelectron spectroscopy.One liquid-phase region,two two-phase regions(liquid-rutile and liquid-ferropseudobrookite),and one three-phase region(liquid-rutile-ferropseudobrookite)were determined.The variation in the TiO_(2)and V_(2)O_(5)contents with the Fe_(2)O_(3)content was examined for rutile and ferropseudobrookite solid solutions.However,on further comparison with the predictions of FactSage 8.1,significant discrepancies were identified,highlighting that greater attention must be paid to updating the current thermodynamic database related to vanadium-bearing slag systems.

Reaction behavior and non-isothermal kinetics of suspension magnetization roasting of limonite and siderite

In order to develop limonite and decrease CO_(2) emissions,siderite is proposed as a clean reductant for suspension magnetization roasting(SMR) of limonite.An iron concentrate(iron grade:65.92wt%,iron recovery:98.54wt%) was obtained by magnetic separation under the optimum SMR conditions:siderite dosage 40wt%,roasting temperature 700℃,roasting time 10 min.According to the magnetic analysis,SMR achieved the conversion of weak magnetic minerals to strong magnetic minerals,thus enabling the recovery of iron via magnetic separation.Based on the phase transformation analysis,during the SMR process,limonite was first dehydrated and converted to hematite,and then siderite decomposed to generate magnetite and CO,where CO reduced the freshly formed hematite to magnetite.The microstructure evolution analysis indicated that the magnetite particles were loose and porous with a destroyed structure,making them easier to be ground.The non-isothermal kinetic results show that the main reaction between limonite and siderite conformed to the two-dimension diffusion mechanism,suggesting that the diffusion of CO controlled the reaction.These results encourage the application of siderite as a reductant in SMR.

Bioleaching and biosorption behavior of vanadium-bearing stone coal by Bacillus mucilaginosus

The recovery of vanadium(V)from stone coal by bioleaching is a promising method.The bioleaching experiments and the biosorption experiments were carried out,aiming to explore the adsorption characteristics of Bacillus mucilaginosus(B.mucilaginosus)on the surface of vanadium-bearing stone coal,and the related mechanisms have been investigated.After bioleaching at 30℃ for 28 d,the cumulative leaching rate of V reached 60.2%.The biosorption of B.mucilaginosus on stone coal was affected by many factors.When the pH value of leaching system is 5.0,strong electrostatic attraction between bacteria and stone coal promoted biosorption.Bacteria in the logarithmic growth phase had mature and excellent biosorption properties.The initial bacterial concentration of 3.5×10^(8) CFU/mL was conducive to adhesion,with 38.9%adsorption rate and 3.6×10^(7) CFU/g adsorption quantity.The adsorption of B.mucilaginosus on the stone coal conformed to the Freundlich model and the pseudo-second-order kinetic model.Bacterial surface carried functional groups(-CH_(2),-CH_(3),-NH_(2),etc.),which were highly correlated with the adsorption behavior.In addition,biosorption changed the surface properties of stone coal,resulting in the isoelectric point(IEP)approaching the bacteria.The results could provide an effective reference for the adsorption laws of bacteria on minerals.

Behaviors of vanadium and chromium in coal-based direct reduction of high-chromium vanadium-bearing titanomagnetite concentrates followed by magnetic separation

The reduction behaviors of FeO·V2O3 and FeO·Cr2O3 during coal-based direct reduction have a decisive impact on the efficient utilization of high-chromium vanadium-bearing titanomagnetite concentrates. The effects of molar ratio of C to Fe n(C)/n(Fe) and temperature on the behaviors of vanadium and chromium during direct reduction and magnetic separation were investigated. The reduced samples were characterized by X-ray diffraction(XRD), scanning election microscopy(SEM) and energy dispersive spectrometry(EDS) techniques. Experimental results indicate that the recoveries of vanadium and chromium rapidly increase from 10.0% and 9.6% to 45.3% and 74.3%, respectively, as the n(C)/n(Fe) increases from 0.8 to 1.4. At n(C)/n(Fe) of 0.8, the recoveries of vanadium and chromium are always lower than 10.0% in the whole temperature range of 1100-1250 °C. However, at n(C)/n(Fe) of 1.2, the recoveries of vanadium and chromium considerably increase from 17.8% and 33.8% to 42.4% and 76.0%, respectively, as the temperature increases from 1100 °C to 1250 °C. At n(C)/n(Fe) lower than 0.8, most of the FeO·V2O3 and FeO·Cr2O3 are not reduced to carbides because of the lack of carbonaceous reductants, and the temperature has little effect on the reduction behaviors of FeO·V2O3 and FeO·Cr2O3, resulting in very low recoveries of vanadium and chromium during magnetic separation. However, at higher n(C)/n(Fe), the reduction rates of FeO·V2O3 and FeO·Cr2O3 increase significatly because of the excess amount of carbonaceous reductants. Moreover, higher temperatures largely induce the reduction of FeO·V2O3 and FeO·Cr2O3 to carbides. The newly formed carbides are then dissolved in the γ(FCC) phase, and recovered accompanied with the metallic iron during magnetic separation.

Basic characteristics of Australian iron ore concentrate and its effects on sinter properties during the high-limonite sintering process

The basic characteristics of Australian iron ore concentrate (Ore-A) and its effects on sinter properties during a high-limonite sintering process were studied using micro-sinter and sinter pot methods. The results show that the Ore-A exhibits good granulation properties, strong liquid flow capability, high bonding phase strength and crystal strength, but poor assimilability. With increasing Ore-A ratio, the tumbler index and the reduction index (RI) of the sinter first increase and then decrease, whereas the softening interval (Delta T) and the softening start temperature (T (10%)) of the sinter exhibit the opposite behavior; the reduction degradation index (RDI+3.15) of the sinter increases linearly, but the sinter yield exhibits no obvious effects. With increasing Ore-A ratio, the distribution and crystallization of the minerals are improved, the main bonding phase first changes from silico-ferrite of calcium and aluminum (SFCA) to kirschsteinite, silicate, and SFCA and then transforms to 2CaO center dot SiO2 and SFCA. Given the utilization of Ore-A and the improvement of the sinter properties, the Ore-A ratio in the high-limonite sintering process is suggested to be controlled at approximately 6wt%.

Synergetic strengthening mechanism of ultrasound combined with calcium fluoride towards vanadium extraction from low-grade vanadium-bearing shale

The effect and mechanism of ultrasound and CaF_(2) on vanadium leaching from vanadium-bearing shale were investigated systematically.In consideration of the enhancement for vanadium recovery,the combination of ultrasound and CaF_(2)(66.28%) exerts more evident effects than ultrasound(26.97%) and CaF_(2)(60.35%) alone,demonstrating the synergetic effect of ultrasound and CaF_(2).Kinetic analysis manifests that the product layer diffusion controls vanadium leaching in ultrasound system without CaF_(2),however product layer diffusion and interfacial reaction is the rate-controlling step for vanadium leaching in other three leaching systems.The combination of ultrasound and CaF_(2) notably decreases the activation energy(E_(a)) from 62.03 to 27.61 kJ/mol,nevertheless individual CaF_(2) only reduces the E_(a) to 50.70 kj/mol.X-ray diffraction and fourier transform infrared spectrometer analyses show that the decomposition degree of the vanadium-bearing mica structure is the most significant in ultrasound and CaF_(2) system,proving the highest release degree of vanadium.Specific surface area and pore distribution combined with scanning electron microscope analyses reveal that the action of ultrasound and CaF_(2) would provide higher specific surface area,more abundant pores structure and cracks for the particles,which further prompts the rapid diffusion of H^(+),F^(-)and HF,and achieves the conspicuous improvement of vanadium leaching recovery.

Effects of reduction on the catalytic performance of limonite ore

The catalytic performance of Ni-containing limonite ore in the dry reforming reaction of methane （CH_4＋CO_2→2H_2＋2CO） was determined before and after hydrogen reduction, and under a flow of hydrogen. After hydrogen reduction, the limonite ore exhibited higher catalytic performance, because of the formation of Fe-Ni. However, the Fe in Fe-Ni was readily oxidized by the input CO_2 gas. resulting in a rapid decrease in the catalytic performance of limonite ore. The performance de- crease was due to a decrease in the Ni surface area; Ni could not dissolve in iron oxides and this caused segregation in the iron oxides. When the reaction was conducted under a hydrogen flow, the Fe-Ni was formed and maintained. Ni was highly dispersed in the Fe-Ni phase, resulting in greater surface area of Ni and higher conversion rate of CH_4 and CO_2. The catalytic performance of the limonite ore was inferior to the Ni/Al_2O_3 catalyst because the effect of catalyst support was small, however, the limonite ore was more stable during catalytic use and much cheaper than the Ni/Al_2O_3.

Recovering limonite from Australia iron ores by flocculation-high intensity magnetic separation

Successful recovery of limonite from iron fines was achieved by using flocculation-high intensity magnetic separation （FIMS） and adding hydrolyzed and causticized flocculants according to the characteristic of iron fines. The separation results of the three iron samples are as follows： iron grade 66.77%- 67.98% and the recovery of iron 69.26%-70.70% by the FIMS process with flocculants. The comparative results show that under the same separation conditions the F1MS process can effectively increase the recovery of iron by 10. 97%- 15.73%. The flowsheet results confirm the reliability of the process in a SHP high intensity magnetic separator. The concentrate product can he used as raw materials for direct reduction iron-smelting. The hydrolyzed and causticized flocculants can selectively flocculate fine feebly-magnetic iron mineral particles to increase their apparent separation sizes. The larger the separation size, the stronger the magnetic force. By comparing the separation results of the three samples it is found that among the three samples the higher the limonite content, the better the separation result. This means that the separation result relates closely to the flocculation process and the adding pattern of the flocculant.

Vanadium extraction from vanadium-bearing titanomagnetite by selective chlorination using chloride wastes (FeClx)

Vanadium extraction of vanadium-bearing titanomagnetite was investigated by selective chlorination. Thermodynamics analyses on the interactive reactions among related species in the system were made before the experiments. Some fundamental experiments for extracting vanadium by FeClx as chlorinating agent were conducted over the temperature range of 900-1300 K under air or oxygen atmosphere. The results show that vanadium can be extracted by the selective chlorination, using FeClx, based on thermodynamic analysis and experiment. Vanadium extraction ratio first increases with the increase of temperature, and then decreases with the increase of temperature over the range of 900-1300 K under air or oxygen atmosphere. The higher molar ratio of FeCI3 to oxides （nchl：noxd） reacting with FeC13, the higher ratio of vanadium extraction. Under oxygen atmosphere, the vanadium extraction ratio is up to 32% at 1100 K for 2 h by using FeCI3 as chlorinating agent.

Suspension roasting process of vanadium-bearing stone coal:Characterization,kinetics and thermodynamics

The thermodynamics,kinetics,phase transformation,and microstructure evolution of vanadium-bearing stone coal during suspension roasting were systematically investigated.Thermodynamic calculations showed that the carbon in the stone coal burned and produced CO_(2) in sufficient oxygen during roasting.The mass loss of stone coal mainly occurred within the temperature range from 600 to 840℃,and the thermal decomposition reaction rate increased to the peak at approximately 700℃.Verified by the Flynn−Wall−Ozawa(FWO)and Kissinger−Akahira−Sunose(KAS)methods,the thermal decomposition reaction of stone coal was described by the Ginstling−Brounshtein equation.The apparent activation energy and pre-exponential factors were 136.09 kJ/mol and 12.40 s^(−1),respectively.The illite in stone coal lost hydroxyl groups and produced dehydrated illite at 650℃,and the structure of sericite was gradually destroyed.The surface of stone coal became rough and irregular as the temperature increased.Severe sintering occurred at the roasting temperature of 850℃.

Leaching behavior of metals from limonitic laterite ore by high pressure acid leaching

The leaching behavior of metals from a nickeliferous limonitic laterite ore was investigated by high pressure acid leaching process for the extraction of nickel and cobalt.The effects of sulfuric acid added,leaching temperature,leaching time and liquid/solid（L/S） ratio on metals extraction were examined.More than 97% Ni,96% Co,93% Mn,95% Mg and less than 1% Fe are extracted under optimum conditions.Analysis of the high pressure acid leaching residue by chemical and XRD analysis indicates that the residual iron and sulfur are mainly present in phases of hematite and alunite,respectively.The high pressure leaching process provides a simple and efficient way for the high recovery of nickel and cobalt from laterite ore,leaving residue as a suitable iron resource.

海南岛新生代火山岩风化型矿产资源特征

海南岛新生代火山岩分布面积广、规模大,在热带条件下形成了风化型矿产资源。褐铁矿、铝土矿、钴土矿等是该区域火山岩风化形成的主要矿种,这些矿种在成矿上受岩性和地形地貌等控制,具有资源丰富、储量大、低品位共(伴)生等特色,在分布上以东西向的王五—文教断裂带为界,北部以褐铁矿为主伴生钴等元素,南部以铝土矿、钴土矿为主常伴生稀土、镓等元素。该区域风化型矿产资源由于受采矿、选矿等因素的限制,大部分尚未得到开发利用,但成矿资源量大、共伴生多种成矿元素、综合利用价值大,在资源开发利用时应予以重视。

钒钛矿烧结生产的研究进展

本文归纳了钒钛矿的烧结特点,分析了钒钛烧结矿强度差、低温还原粉化现象严重的主要原因,介绍了增加铁酸钙黏结相量、控制燃料配比、控制烧结温度、配加褐铁矿、强化制粒、复合造块及烧结矿表面喷洒CaCl_(2)/B_(2)O_(3)溶液等能够改善钒钛矿烧结指标的技术措施,展望了钢铁企业钒钛矿强化烧结面临的问题及解决方案。

某氰化尾渣中磁选回收铁试验研究

为综合回收利用某含金银多金属氧化矿氰化尾渣中的铁,针对氰化尾渣进行了弱磁选和强磁选回收铁的试验研究。试验结果表明:在弱磁粗选磁场强度为238.85 kA/m,弱磁精选磁场强度为159.24 kA/m,弱磁粗选尾矿强磁选磁感应强度为1200 mT的条件下,通过弱磁—强磁分选工艺,获得了全铁品位为64.08%、铁回收率为21.11%的弱磁铁精矿和全铁品位为45.81%、铁回收率为40.31%的强磁铁精矿,综合全铁回收率为61.42%,达到了综合回收利用铁资源的目的。

红土镍矿硝酸加压浸出渣制备电池级磷酸铁

近年来,在我国“碳达峰”和“碳中和”目标的引领下,新能源行业发展迅速,新能源汽车的推广与使用促进了锂离子电池行业的蓬勃发展。作为三元锂电池的关键原材料,镍的需求量不断增加。但由于硫化镍矿日益枯竭,红土镍矿逐渐成为了主要的提镍原料,在镍产量中占比超过70%。褐铁型红土镍矿在红土镍矿中占比超过60%,经硝酸加压浸出(NAPL)提取镍钴后产生的浸出渣中含有丰富的有价金属资源(铁含量>60%),浸出渣的综合利用对资源回收和环境保护具有重要意义。以褐铁型红土镍矿硝酸加压浸出渣为原料,在磷酸单一介质中制备电池级磷酸铁材料。以磷酸为介质,通过预浸、溶解实现浸出渣中铁的高效提取。预浸时磷酸溶液浓度较低,可以使含铁相初步转型为FePO_(4)·2H_(2)O,同时除去浸出渣中Cr、Mg、Al等杂质元素。然后采用高浓度磷酸溶液溶解处理预浸渣,实现Fe的完全溶解。最后稀释调节pH值直接沉淀制备磷酸铁,得到FePO_(4)·2H_(2)O产品,该产品不含杂质元素Mg、Si,Cr、Al的含量为0.019%、0.016%。通过XRD、SEM、EDS等技术手段对预浸渣和磷酸铁产品的物相组成和微观形貌进行了研究,明确了预浸过程可实现铁由Fe_(2)O_(3)向FePO_(4)·2H_(2)O的转变,最终产品的晶体结构与标准磷酸铁相匹配。由磷酸铁合成的磷酸铁锂材料也表现出优异的电化学性能。该研究有望实现对褐铁型红土镍矿硝酸加压浸出渣中宏量组元铁的高值化利用,从而优化磷酸铁制备工艺。

某难选铁矿磁—重—浮联合选矿试验研究

为确定某难选铁矿石的更高效开发利用工艺,基于矿石性质研究开展了详细的选矿工艺试验。结果表明:①矿石中主要有用成分铁品位为47.26%,铁主要分布于赤褐铁矿中,其次分布于磁铁矿中;主要杂质SiO_(2)含量为28.69%,有害成分S、P含量很低。②矿石采用一段磨矿—弱磁选—强磁选—螺旋溜槽重选—二段磨矿—阳离子反浮选流程处理,获得了产率55.26%、铁品位65.32%、铁回收率76.86%的铁精矿,精矿品质达到了业主要求,可作为选厂技术改造的依据。

利用褐铁矿型红土镍矿烧结矿制备Fe-Cr-Ni合金

我国是不锈钢第一生产大国,但作为冶炼不锈钢主要原料的镍矿及铬铁矿资源贫乏,占红土镍矿资源总量60%以上的褐铁矿型红土镍矿与低品位铬铁矿愈发受到关注。同时,不锈钢冶炼通常需先分别生产铬铁和镍铁,工艺流程长,生产成本高。因此,本文基于烧结—高炉工艺,利用褐铁矿型红土镍矿烧结矿低成本地一步制备出了Fe-Cr-Ni合金。通过热力学分析及熔炼参数的优化,重点研究了不同Cr_(2)O_(3)含量的含镍烧结矿(S1:4.84 wt%;S3:7.72 wt%)的熔炼特性。在熔炼时间60 min(S1)/90 min (S3)、熔炼温度1600℃、焦粉用量20 wt%、炉渣碱度1.0的最佳条件下,成功制备出了铬品位5.6 wt%~9.3 wt%、镍品位1.55 wt%~1.70 wt%、铁品位84 wt%~88 wt%的Fe-Cr-Ni合金,其铬、镍和铁的回收率分别在90%、98%和96%以上。研究表明,含镍烧结矿Cr_(2)O_(3)含量的提高会造成熔炼时间的延长,这不利于焦比的降低与不锈钢产量的提高。在后续研究中,将开发出由含镍烧结矿与含铬球团矿构成的综合炉料结构,以更有效地实现高铬镍铁的冶炼。

某红土型镍矿中镍钴的赋存状态对其回收的影响

褐铁矿型红土镍矿是一种富含镍、钴、铁的重要资源,综合利用价值巨大。探究红土型镍矿中镍和钴的赋存状态,以深入了解赋存状态对镍和钴回收利用的影响。通过详细的工艺矿物学研究,明确镍和钴主要赋存于褐铁矿、锰的水合氧化物和锰镍矿中,根据该红土型镍矿特征判断最佳冶炼回收方法为高压酸浸工艺。研究为红土型镍矿的资源高效利用提供了重要参考,为相关工业应用和环境保护提供了有益启示。

高铁低硫型铝土矿的工艺矿物学研究

铝土矿主要由铝的氢氧化物、氧化物和硅酸盐矿物组成,是生产金属铝的主要原料。以某高铁低硫型铝土矿为研究对象,采用元素分析、X射线衍射和扫描电镜等方法,研究铝土矿的化学组成、主要矿物的嵌布关系、矿物表面形貌等。结果表明,矿石中Al_(2)O_(3)含量为44.22%,SiO_(2)含量为5.71%,二者的比值约为7.74。矿石中主要矿物为三水铝石,褐铁矿(水针铁矿)和勃姆石含量较少。它既含有少量石英、高岭石、绿泥石和钛铁矿,又含有微量钠长石、方解石、磷灰石、一水硬铝石、铁素体和金红石等。褐铁矿中分散有微量铝,大多数褐铁矿和石英以极细粒夹杂物的形式包裹在铝矿物集合体中。矿物粒度分析表明,铝矿物集合体嵌布粒度不小于0.074 mm的累计含量为92.50%,较集中于0.015~0.060 mm,嵌布粒度小于0.010 mm的含量为0.5%;铁矿物集合体嵌布粒度不小于0.074 mm的累计含量为34.45%,嵌布粒度小于0.010 mm的含量较高,为43.44%;石英嵌布粒度不小于0.074 mm的累计含量为40.15%,嵌布粒度小于0.010 mm的含量较高,为39.86%。矿石中的大部分铝以独立矿物的形式存在。

某含铁铜尾矿回收微细粒弱磁性铁试验研究

某铜尾矿中含铁29.38%,经工艺矿物学研究发现,这些铁主要赋存在赤铁矿和褐铁矿中,它们粒度细小,磁性较弱,且部分铁矿物嵌布关系复杂。为了经济有效地回收这些铁矿物,并针对该类含铁矿物回收过程中存在的回收率低、精矿品位低的难题,进行了选矿试验研究。试验结果表明:在粗选磁感应强度为1.6 T,粗精矿磨矿细度为-0.074 mm78%,精选磁感应强度为1.0 T的条件下,采用强磁粗选—粗精矿再磨再选工艺流程,可获得铁品位为60.01%,铁回收率为36.10%的铁精矿,实现了该尾矿的资源化再利用。