正交实验法优化高纯氧化钕制备工艺参数

利用草酸作为稀土沉淀剂,制备高纯氧化钕时,工艺条件控制不当,料液中的杂质会发生共沉淀现象,影响产品纯度。利用正交实验法优化草酸沉淀稀土的工艺参数,选择沉淀温度、草酸用量、沉淀pH值及陈化时间作为沉淀工艺的主要影响因素,采用极差和方差分析,发现各因素对稀土收率的影响显著性较小,对铝除杂率的显著性影响由大到小顺序为A(沉淀pH值)C(沉淀温度)B(草酸用量)D(陈化时间),降低沉淀pH值、增加草酸用量、降低沉淀温度、增加陈化时间有利于提高铝除杂率。制备高纯氧化钕的最佳工艺条件为沉淀pH值2.0,沉淀温度30℃,草酸用量1.8倍,陈化时间10 h。     

氢氧化钠焙烧法提取稀土电解渣中稀土的工艺研究

针对目前从氟盐体系稀土熔盐电解渣中回收稀土效率低的问题,提出了一种NaOH焙烧-盐酸优溶浸出法。系统考察了焙烧温度、焙烧时间、NaOH添加量,以及盐酸浓度、液固比、浸出温度、浸出时间对渣中稀土提取效果的影响。结果表明:在焙烧温度600℃、焙烧时间1.5h、NaOH与稀土熔盐电解渣质量比0.8∶1、盐酸浓度2mol/L、液固比8∶1、浸出温度40℃、浸出时间15min的工艺条件下,稀土浸出率为99.22%。     

由含锌烟尘制备高纯硫酸锌溶液的工艺研究

对锌烟尘硫酸浸出提取锌工艺条件进行了研究,分别采用正交试验与单因素试验考察浸出酸浓度、液固比、浸出时间、浸出温度对锌烟尘中锌、铁的浸出率的影响;采用针铁矿-氧化水解联合法深度除铁、过硫酸铵氧化除锰、锌粉置换除杂对浸出液净化.结果表明,较优浸出工艺条件为:硫酸浓度为1.Omol,L、液固比为7:1、浸出时间为2.5 h、浸出温度为60℃,在较优浸出条件下,锌浸出率可达97%以上;浸出液经过净化后得到高纯度的硫酸锌溶液.表明该工艺从锌烟尘中提取锌具有较好的效果.     

浸出条件对稀土和铁浸出率的影响试验

以稀土精矿浓硫酸焙烧工艺中焙烧矿水浸过程为对象,研究了焙烧矿浸出温度、浸出时间、焙烧矿粒度等条件对稀土、铁浸出率的影响,并对水浸渣中稀土赋存状态进行了研究。研究表明,浸出温度和焙烧矿粒度对稀土、铁的浸出速率有较大影响,但对其浸出率没有影响,延长浸出时间,焙烧矿中的可溶性稀土、铁均可被浸出。水浸渣中的稀土主要以磷酸盐和氟氧化稀土形式存在,铁主要以磷酸铁形式存在,并含有少量硫化铁。     

从荧光粉废料中提取稀土工艺研究

采用4种方案从荧光粉废料中提取稀土元素,并考查了盐酸法提取稀土时盐酸和双氧水用量对稀土浸出率的影响,随后采用碳酸钠焙烧法提取渣中较难浸出的铈、铽,最后采用中和法对酸浸出液进行除杂。结果表明,100g物料盐酸最佳用量为150mL,双氧水用量为20mL,钇、铕浸出率可达99%。经碳酸钠焙烧—盐酸浸出后铽浸出率达到55%,除杂后铁、硅、铝含量分别降至11.47mg/L、15.93mg/L和150mg/L。     

碱法从石煤中浸出钒试验研究

采用造球—氧化焙烧—碱浸的方法从石煤中浸出钒,考察了焙烧温度、焙烧时间、浸出温度、浸出剂浓度、浸出时间、浸出液固比对浸出率的影响,获得了88.38%的高浸出率。研究表明,焙烧温度、浸出温度、浸出剂浓度、浸出时间是浸出率的重要影响因素。适宜的工艺条件是:焙烧温度850℃、焙烧时间3 h、浸出温度90℃、浸出剂浓度2 mol/L、浸出时间2 h、浸出液固比3。     

稀土矿硫酸铵焙烧法提取稀土

探究了稀土精矿和稀土尾矿硫酸铵焙烧水浸稀土工艺。研究发现,氟碳铈矿预活化焙烧处理后与硫酸铵混合焙烧,稀土矿物转变为可溶性硫酸稀土盐,预活化焙烧处理有助于提高硫酸铵焙烧过程中稀土矿物向硫酸盐的转变,进而提高稀土浸出率,稀土浸出率最大达到90%。稀土尾矿煤基还原焙烧-磁选铁富集稀土,该过程不仅得到了铁精矿和富稀土渣,尾矿中氟碳铈矿得到活化分解有利于硫酸铵焙烧过程中的物相转变。针对选铁后的富稀土渣分别考虑了硫酸铵配比、焙烧温度和焙烧时间对稀土浸出率的影响。得出富稀土渣最佳硫酸铵焙烧条件:硫酸铵配比为4∶1,焙烧温度350℃,焙烧时间45 min,80℃热水浴浸出时间2 h,浸出液液固比10 m L·g-1,La、Ce、Nd最高浸出率分别为82.83%,76.53%,77.14%。     

从稀土抛光粉废料中回收稀土试验研究

研究了从稀土抛光粉废料中回收稀土,考察了稀土抛光粉预处理方式、焙烧产物粒度、氢氧化钠用量、焙烧温度和焙烧时间对稀土的盐酸浸出率的影响。试验结果表明,稀土抛光粉加NaOH焙烧,NaOH用量与抛光粉质量比为0.18、焙烧温度450℃、焙烧时间2.5h最优条件下,稀土的盐酸浸出率平均高于98%。     

常压硫酸焙烧法提取镍磷铁中的镍

采用硫酸化焙烧再水浸的方法从钙镁磷肥的副产物镍磷铁中提取镍,重点研究了提镍过程中相关因素对镍浸出率的影响。结果表明,在酸料比0.5、焙烧温度300℃、焙烧时间3h、水浸液固比7∶1、水浸温度70℃、水浸时间2.5h的条件下,浸出效果最好,浸出液中镍浸出率达到73.43%。     

从镧系光学玻璃废料中回收氧化镧

探究用盐酸从某种镧系光学玻璃废料中浸出氧化镧,从浸出过程中盐酸的浓度、浸出温度、液固比和浸出时间方面对各元素浸出率的影响进行了研究,并得出了镧的最佳浸出条件;利用水解沉淀法除去浸出液中杂质离子;采用草酸对除杂浸液中的镧进行沉淀分离,得到纯度为99.2%的氧化镧,总回收率达到96.8%。     

Recovery of rare earth and cobalt from Co-based magnetic scraps

The reuse of RE and cobalt in Co-based magnetic scraps was studied.The optimized feat lixiviated condition was:200 mesh,sulfuric acid dosage was of 1.4 times theoretic dosage,temperature was 80 oC and leaching time 1 h.The optimum technology conditions was:Na2S2O8 dosage was of 8 times theoretic dosage,oxidation temperature 80 oC,oxidation time 2 h and pH=4.5.Rare earth was precipitated by saturated(NH4)2C2O4 solution,after roasting of rare earth oxalate,rare earth oxide was received.Cobalt-iron residue was soaked by hydrochloric acid,the Fe(OH)3 was preferential solution,pH was adjusted to 1.4 by hydrochloric acid,Co(OH)3 did not dissolve,cobalt and iron were separated,after roasting of Co(OH)3,cobalt oxide was received.The total recovery of cobalt was found to be 97% and rare earths was 96%.     

Decomposition of mixed rare earth concentrate by NaOH roasting and kinetics of hydrochloric acid leaching process

A new clean extraction technology for the decomposition of Bayan Obo mixed rare earth concentrate by NaOH roasting is proposed.The process mainly includes NaOH roasting to decompose rare earth concentrate and HCl leaching roasted ore.The effects of roasting temperature,roasting time,NaOH addition amount on the extraction of rare earth and factors such as HCl concentration,liquid-solid ratio,leaching temperature and leaching time on the dissolution kinetics of roasted ore were studied.The experimental results show that when the roasting temperature is 550℃ and the roasting time is 60 min,the mass ratio of NaOH:rare earth concentrate is 0.60:1,the concentration of HCl is 6.0 mol/L,the ratio of liquid to solid(L/S) 6.0:1.0,and the leaching temperature 90℃,leaching time 45 min,stirring speed 200 r/min,and the extraction of rare earth can reach 92.5%.The relevant experimental data show that the process of HCl leaching roasted ore conforms to the shrinking core model,but the control mechanism of the che mical reaction process is different when the leaching temperature is different.When the leaching temperature is between 40 and 70℃,the chemical reaction process is controlled by the diffusion of the product through the residual layer of the inert material.The average surface activation energy of the rare earth element is E_a=9.96 kJ/mol.When the leaching temperature is 75-90℃,the chemical reaction process is controlled by the interface transfer across the product layer(product layer interface mass transfer) and diffusion.The average surface activation energy of rare earth elements is E_a=41.65 kJ/mol.The results of this study have certain significance for the green extraction of mixed rare earth ore.     

硫酸焙烧分解包头混合稀土精矿添加铁泥的研究

在硫酸焙烧分解包头混合稀土精矿工艺中,利用处理钕铁硼废料所产生铁泥替代铁粉,通过焙烧分解、P204转型得到氯化稀土溶液,并与原工艺得到的的溶液进行对比,结果表明,使用铁泥和使用铁粉达到了相同的工艺效果,铁泥中的稀土得到了很好的回收。     

Oxidative Roasting–Selective Pressure Leaching Process for Rare Earth Recovery from NdFeB Magnet Scrap

To recover rare earths (RE) with low acid consumption and low environmental pollution, selective pressure leaching with hydrochloric acid from roasted NdFeB scrap was explored. The phase evolution of NdFeB scrap during roasting at 800 °C as a function of time was confirmed, and after complete oxidation, its phase components consisted of Fe2O3, NdFeO3, and NdBO3. In the selective pressure leaching procedure, the optimal leaching was achieved at 110 °C for 30 min, in which the leaching rate of rare earth was 96.27% along with 13.33% of Fe. Subsequently, the effects of the hydrochloric acid dosage, the hydrochloric acid concentration and the particle size of the roasted NdFeB powder on the leaching rate of rare earth were investigated. For leaching at 110 °C for 30 min, the leaching of 13.33% Fe2O3 was derived from the Fe2O3 and NdFeO3 phases in the fully oxidized NdFeB scrap. This phenomenon was verified by the leaching of Fe from Fe2O3 of analytical purity and synthetic NdFeO3. Moreover, the leaching of Nd and Fe from the NdFeO3 phase was found to occur simultaneously. The advantages of the selective pressure leaching process using hydrochloric acid for the oxidized NdFeB scrap were comprehensively evaluated.     

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, HNO₃ concentration, liquid–solid 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 TG–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 HNO₃ concentrations and liquid–solid ratio are determined to be 7.609 and 2.516, respectively. Besides, an empirical rate equation is obtained to describe the process.     

High-efficiency simultaneous extraction of rare earth elements and iron from NdFeB waste by oxalic acid leaching

Iron can not be recovered at high value because only rare earth elements are effectively recovered from NdFeB waste via oxidation roasting-hydrochloric acid leaching process.In this study,a new method for leaching NdFeB waste with oxalic acid was developed.The high-efficiency,simultaneous and high-value recovery of rare earth elements and iron was realized to simplify the process and improve the economic benefit.Results of the oxalic acid leaching experiments show that under the optimum leaching conditions at 90℃ for 6 h in the aqueous solution of oxalic acid(2 mol/L) with a liquid-solid ratio of60 mL/g,the iron leaching efficiency and precipitation rate of rare earth oxalate reach 93.89% and 93.17%,respectively.Rare earth oxalate and Fe(C₂O₄)3^3- were left in the residue and the leaching solution,respectively.The leaching mechanism was further analyzed by characterising the leach residues obtained through X-ray powder diffraction(XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS).Results of the leaching kinetics study indicate that the process of oxalic acid leaching follows the shrinking nucleus model,and the leaching kinetics model is controlled by the mixed factors of diffusion and chemical reaction.The leaching residue was calcined at 850℃ for 3 h and then decomposed into rare earth oxide,which can be directly used to prepare rare earth alloy via molten salt electrolysis.For the leaching solution,ferric oxalate solution was reduced using Fe powder to prepare the ferrous oxalate(FeC₂O₄-2H₂O).     

钕铁硼磁材二次废料制备高纯硫酸亚铁

钕铁硼磁材废料经回收稀土后产生大量的二次废料,针对该废料含铁量高的特点,对废料中的铁元素提取进行了相关研究,铁元素以硫酸亚铁产品形式回收。酸浸提铁阶段考察了酸浓度、浸提温度、反应时间、液固比（酸体积/废渣质量）、浸取次数等因素对铁离子浸出效果的影响,通过单因素实验得到较优的酸浸工艺参数:硫酸浓度6 mol/L、浸提温度80 ℃、反应时间120 min、液固比4∶1（mL/g）和浸取次数2次,在此条件下铁的浸出率约为97.8%。还原阶段考察了温度、反应时间及废铁屑过量系数等因素对Fe3+转化为Fe2+效果的影响,得到较优的还原工艺参数:还原温度为80 ℃、反应时间为120 min和废铁屑过量系数为1.2,在此优化条件下,Fe3+转化为Fe2+的转化率约为97.69%。最终采用浓缩、冷却结晶、重结晶的方法制得硫酸亚铁产品,产品纯度99.92%。      

铝土矿盐酸浸出过程研究

以澳大利亚难处理三水铝土矿为对象、盐酸为浸出剂进行无焙烧浸出试验,考察浸出温度、矿物粒度以及浸出时间对氧化铝浸出率的影响。结果表明,优化工艺条件为:矿物粒度-55μm、浸出温度100~110℃、浸出时间120 min、盐酸浓度10%、浸出液固比100∶7。此条件下氧化铝的浸出率为95.49%,氧化铁的浸出率为96.72%。以该酸浸液为原料,使用TBP-苯体系进行铝铁分离萃取试验,在萃取温度25℃、相比O/A=1∶1、盐酸浓度1.5 mol/L,萃取时间10 min的条件下,经单级萃取,溶液中铁元素的萃取率可达95%,铝元素损失率为6%,铁铝萃取分离系数为408,经3级以上逆流萃取,铁铝分离系数可达800以上。以纯水作为反萃剂,在温度25℃、相比O/A=1∶1、反萃时间5 min、单级反萃,铁的反萃率达95%。     

某低品位稀土复合矿综合利用试验研究

对西南某地低品位稀土复合矿采用焙烧-酸浸工艺,稀土的浸出率大于81%,Nb的浸出率大于88%,Ga的浸出率可达99.08%,较好地实现了该稀土复合矿的综合利用。