Coordination leaching of tungsten from scheelite concentrate with phosphorus in nitric acid

A hydrometallurgical process for tungsten extraction and recovery from scheelite is reported.The technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions,extracting tungsten by solvent extraction and reusing leaching agent.In the leaching process,affecting factors,such as temperature,leaching time,nitric acid and dosage of phosphoric acid,were examined on recovery of tungsten.Results show that more than 97%of tungsten could be extracted under conditions of leaching temperature of 80-90°C,HNO3 concentration of 3.0-4.0 mol/L,liquild-to-soild ratio of 10:1,H3PO4 dosage of 3 stoichiometric ratio and leaching time of 3 h.Solvent extraction was then employed for the W recovery from the leachate with a organic system of 40%(v/v)N235,30%(v/v)TBP,and 30%sulfonated kerosene.Approximately 99.93%of W was extracted and ammonium tungstate solution containing 193 g/L W was obtained with a stripping rate of 98.10%under the optimized conditions.

Pressure nitric acid leaching of alkali-pretreated low-grade limonitic laterite

The pressure nitric acid leaching of alkali-pre- treated low-grade limonitic laterite, as well as removing impurity AI（III） and preparing intermediate product of nickel/cobalt sulphide from leaching liquor were investi- gated. After pretreatment, iron exists in the form of amorphous iron oxides, while nickel is adsorbed on the surface of iron oxides in the form of nickel oxide. The preferable pressure leaching conditions are determined as follows： leaching temperature of 458 K, leaching duration of 60 min, initial acidity of nitric acid of 1.90 mol.L-~ and liquid to solid ratio of 3：1 （volume to mass ratio）. Under these conditions, the leaching efficiencies of Ni, Co and A1 are 95 %, 88 % and 55 %, respectively, and that of Fe is less than 1%. The loss rates of Ni and Co are 1.8 % and 1.5 %, respectively, during the step of removing impurity AI（III）. The sulphide precipitation process produces the interim production of nickel/cobalt sulphides, recovering greater than 99 % of Ni and Co in the purified solution. The iron-rich （〉60 %） pressure leaching residue with low Cr, S can be further reclaimed as the raw materials for iron making.

Kinetics of nitric acid leaching of cerium from oxidation roasted Baotou mixed rare earth concentrate

The kinetics of nitric acid leaching of cerium was investigated for the oxidation roasted Baotou mixed rare earth concentrate. The effects of leaching temperature, HNO_3 concentration, liquidesolid ratio(L/S)and stirring rate on rare earth extraction were studied. The XRD and SEM mapping analysis of the samples before and after acid leaching shows that the roasted bastnaesite is completely leached. Besides,the decomposition process of oxidizing roasting was also obtained by TGe MS and XRD. Different kinetics models were applied in this leaching process. The results of dynamic fitting show that the leaching process can be described by a new variant of the shrinking-core model. And the leaching rate is controlled by both the interfacial transfer and diffusion through the product layer. The apparent activation energy is calculated as 76.78 kJ/mol and the reaction orders with respect to HNO_3 concentrations and liquidesolid ratio are determined to be 7.609 and 2.516, respectively. Besides, an empirical rate equation is obtained to describe the process.

Hydrometallurgical Processing of a Nigerian Galena Ore in Nitric Acid: Characterization and Dissolution Kinetics

The physico-chemical characterization and dissolution kinetics study of a Nigerian galena ore in nitric acid has been undertaken. The effects of acid concentration, temperature, particle size, stirring speed and solid/liquid ratio on the leaching of galena were investigated. The X-ray fluorescence data showed that the galena ore used in the study exists mainly as PbS. Lead (Pb) was detected as the major metal for galena with metals such as Na, Ca, Fe, Zn, Al and Mg occurring as minor elements. The XRD analysis also confirmed the originality of the galena ore as it revealed that galena exists mainly as lead sulphide (PbS). The Fourier transform infrared (FTIR) analysis also supported the XRF and XRD analysis by revealing the presence of sulphur in the ore. The scanning electron micrograph (SEM) analysis revealed a high level of crystallinity of the ore. Results of the leaching studies showed that galena dissolution in nitric acid (HNO3) increases with increasing concentration of nitric acid, temperature and stirring rate, and decreases with increasing particle diameter and solid/liquid ratio. In 10 M HNO3 at a temperature of 90°C using 75 μm particle diameter with solid/liquid ratio of 20 g/L and stirring speed of 540 rpm, about 84.5% of galena was dissolved in 150 minutes. The values of activation energy, order of reaction and Arrhenius constant calculated at the conditions above for galena were 27.01 KJ/mol, 0.93, 26.71 s-1 respectively. The mechanism of dissolution of galena was established to follow the shrinking core model for the diffusion controlled mechanism, with surface chemical reaction as the rate controlling step for the leaching process. Finally, the XRD analysis of the post-leaching residue revealed the presence of gahnite and anglesite.

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。

富铼渣氧化浸出试验研究

根据Re等金属赋存状态,采用硫酸+硝酸体系对富铼渣进行氧化浸出,考察各因素对浸出率的影响大小。通过单因素试验得出最优试验条件为:液固比3:1,反应时间2h,浸出温度60℃,硝酸质量浓度5%,硫酸质量浓度15%,Re、Cu的浸出率分别达到94%、95%以上,As、Bi的浸出率分别在50%、2%以下。

THERMODYNAMIC AND STRUCTURAL CHEMISTRY DISCUSSIONS FOR OXIDATIVE LEACHING OF Cu－Ni SULPHIDE ORE UNDER ATMOSPHERIC PRESSURE

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高镁磷尾矿硝酸分解过程研究

在磷尾矿回收利用过程中,酸解是至关重要的一步,而酸解的效率往往并不理想。针对该问题,以湖北某高镁磷尾矿为对象,对其硝酸分解过程的反应热力学进行了分析,研究了不同参数条件对磷尾矿硝酸分解效果的影响,并对酸浸液和酸浸渣进行了成分分析。研究结果表明:在硝酸溶液体系下,高镁磷尾矿的分解反应在常温下可自发进行,液固比为3.8∶1,硝酸浓度为34%的条件下,磷尾矿的分解效率最高,达到了91.84%,此时白云石基本已溶解完全,而部分氟磷灰石未完全溶解。

基于磷酸铁锂提锂渣的电池级磷酸铁制备工艺研究

目前在磷酸铁锂电池正极材料回收时往往仅回收其中经济价值高的锂元素,而产生的提锂渣中大量磷酸铁因杂质中的铝元素脱除困难导致无法回收利用,造成了巨大的资源浪费。为此,提出了一种使用硝酸浸提磷酸铁的方法。首先在浸出液中加入甲醇电解还原浸出液中的铁离子,再向还原液中加入氢氟酸作为沉淀剂脱除酸浸液中的铝离子,脱铝后的酸浸液用过氧化氢将亚铁离子氧化为铁离子,再加入甲醛并加热沉淀出电池级磷酸铁。研究结果表明:在浸取温度70℃、硝酸浓度5 mol/L、酸浸40 min的条件下,Fe的浸出率为92.7%;经电解还原亚铁后脱铝制备出了Al质量分数仅为72 mg/kg的磷酸铁,满足HG/T 4701-2021《电池用磷酸铁》的Ⅱ型标准。该方法为磷酸铁锂提锂渣的回收利用提供了一条新思路。

废旧磷酸铁锂正极粉脱锂后的磷铁渣经硝酸浸出除铝的研究

针对废旧磷酸铁锂正极粉脱锂后的磷铁渣含铝量偏高的问题,开展了无机酸体系浸出磷铁渣除铝的研究,重点考察了酸种类、酸浓度、液固比、浸出温度、浸出时间等参数对Fe、Al浸出规律的影响。结果表明,Fe、Al在硝酸中的浸出率差异,大于在硫酸或磷酸中的浸出率差异。在硝酸体系中,当酸浓度为0.2mol·L^(-1)、液固比为10∶1、浸出温度为70℃、浸出时间为8.0h时,Al、Fe的浸出率分别为96.3%和3.92%。硝酸酸浸法可扩大磷酸铁与铝的浸出率差异,实现铝的选择性溶出,达到深度除铝的目的。

硝酸浸出—沉淀法梯级提取磷精矿中的磷和稀土

采用硝酸浸出—沉淀法梯级提取磷精矿中的磷和稀土。采用硝酸溶液浸出磷精矿,并重点研究硝酸浓度和浸出温度对磷和稀土浸出的影响。针对硝酸浸出液,先后通过加入草酸和氯化钙沉淀剂分步梯级沉淀溶液中的稀土和磷,并重点研究草酸用量对稀土沉淀以及氯化钙用量对沉磷的影响。结果表明:在液固比5、硝酸浓度400 g/L、常温条件下浸出2 h得到硝酸浸出液,硝酸浸出液分步沉淀提取草酸稀土和活性磷酸钙;最终获得P_(2)O_(5)品位为38.54%的活性磷酸钙,P_(2)O_(5)回收率为99.04%,REO品位为1.673%的草酸稀土,REO回收率为95.28%,可实现磷和稀土的有效分离。

双氧水协同硝酸浸出失效银催化剂中银的研究

在传统硝酸浸出含银废催化剂中银的基础上,研究了双氧水浸出银的影响。在2mol/L HNO_(3),浸出温度70℃,浸出时间120min,固液比1:4条件下,通过逐次加入双氧水,银浸出率为99.76%,获得了较好浸出效果。浸出过程中,双氧水将Ag氧化为Ag_(2)O,可有效提高银的浸出率,同时硝酸与银反应产生的氮氧化物被双氧水氧化生成硝酸继续参加反应。采用硝酸-双氧水作为浸出剂保证了银高效浸出,减少了氮氧化物排放,为含银废催化剂绿色高效回收提供了理论基础及技术支撑。

红土镍矿湿法浸出工艺的进展

阐述并分析了处理红土镍矿的传统湿法工艺,总结了近年来湿法处理红土镍矿的新工艺,最后展望了红土镍矿处理工艺未来主要的发展方向,指出加压酸浸—常规浸出(HPAL-AL)工艺、硝酸加压浸出工艺和矿改性后常压水浸工艺具有广阔的应用前景。

黄磷炉渣精制白炭黑的实验研究

以黄磷炉渣为原料,经硝酸浸出,钙元素以硝酸钙的形式分离,浸出渣经洗涤、干燥、煅烧可得到优质的白炭黑产品。白炭黑SiO2含量达到98.80%,Fe含量11mg/kg,比表面积201cm2/g。研究表明,浸出的最佳工艺条件为:搅拌速度360r/min,反应时间4h,反应温度80℃,液固比为10:1,硝酸浓度20%,浸出渣洗涤终点pH=6.0。

硝酸浸出失效催化剂提取银的实验研究

采用硝酸浸出失效催化剂提取其中金属银,研究了失效催化剂粒度、硝酸用量、浸出温度、浸出时间和洗涤次数等因素对银浸出率的影响。结果表明,失效催化剂粒度对银浸出率影响显著,增加洗涤次数有利于提高银的浸出率。通过实验,确定了合理的工艺参数为:硝酸用量为失效催化剂质量的70%、浸出温度65℃、浸出时间3 h、催化剂粒度为0.125～0.18 mm、搅拌洗涤3次。在此条件下,银的浸出率为99.52%,浸出渣含银0.072%。综合实验结果表明,从失效催化剂到海绵银产品,银的直收率达到99.27%。

硝酸浸取黄磷炉渣制沉淀SiO_2的性能研究

以黄磷炉渣为原料,经硝酸浸出,钙元素以硝酸钙的形式分离,浸出渣经洗涤、干燥、煅烧可得到优质的白炭黑产品。白炭黑SiO2含量达到98.50%,Fe含量11.90mg/kg,比表面积249m2/g,白度90.24%,经X射线衍射分析表明产品为无定形SiO2。研究表明,浸出的最佳工艺条件为:浸取反应时间为6h,浸取反应温度100℃,浸取反应硝酸浓度25%。

以含铜硒的粗碲为原料采用化学法制备高纯碲(英文)

以含铜、硒的粗碲为原料,采用硝酸氧化、盐酸浸出、二氧化硫还原、氢气气氛高温处理的化学方法制备高纯碲。在浓硝酸(69%)用量为化学计量的0.96倍、液固比为4:1、反应温度为20°C、反应时间为30min的条件下,用硝酸氧化粗碲,粗碲中铜的去除率达到99%。粗碲氧化后用盐酸浸出,在浓盐酸用量为化学计量的1.67倍、液固比为4:1、反应温度为20°C、反应时间为30min的条件下,碲的浸出率为99%。浸出液中Te(IV)经二氧化硫还原,碲粉纯度达到99.95%。碲粉在反应温度为730K的氢气中处理30min,其纯度由99.95%上升到99.9995%。

含稀土磷灰石精矿中稀土的分离研究

采用硝酸浸出—中和沉淀工艺分离含稀土磷灰石精矿中的稀土和磷。结果表明,精矿磷浸出率98.80%,稀土浸出率65.34%。硝酸浸出液经碳酸铵中和沉淀后,磷沉淀率12.07%,稀土沉淀率为93.78%。简化工艺流程后稀土浸出率为4.35%,磷浸出率为87.34%。实现了稀土和磷的分离。

银阳极泥硝酸浸出液中铂和钯的还原富集

银阳极泥在硝酸浸出时,大部分铂和钯会进入溶液,最终返回熔炼系统,铂钯直收率因此偏低。研究了亚硫酸氢钠还原沉淀硝酸浸出脱银液中铂和钯的工艺条件。结果表明,还原剂用量、硝酸浓度、反应温度和时间均对铂和钯沉淀率有影响。在优化条件下,铂和钯的沉淀率分别可达到99.5%和99.7%,所得精矿中铂和钯含量分别为1.70%和13.59%。

从多金属精矿中湿法综合回收金银铜铅的研究

对于含金、银、铜、铅的浮选精矿，为综合回收其中的金、银、铜、铅，进行了六种湿法方案的对照研究，以氨浸脱铜硝酸脱铅氰化提金银方案为优，金、银、铜、铅的回收率分别可达９５％、８５％、９０％及９８％，并对此方案进行了批料为５ｋｇ规模的全工艺流程验证试验及半工业验证试验，结果与小型实验一致。该工艺氧化氨浸脱铜在８０℃及８０ｋＰａ下操作，操作简单，金属综合回收率高，易于工程实施，氨及硝酸可循环使用，所得产品为氧化铜、氧化铅及金、银。