Extraction of Rare Earth Elements as Oxides from a Neodymium Magnetic Sludge

We propose a simple method for separating rare earth elements as oxides from a neodymium magnetic sludge by focusing on the affinity of oxygen for the rare earth elements (Nd, Dy, and Pr) and Fe. We have conducted separation experiments with a carbon crucible as contact material to confirm that carbon maintains the oxygen potential in the coexistence region of rare earth oxides and metallic Fe. In this work, the oxide phase of the rare earth elements and the alloy phase that primarily consists of Fe were separated clearly when the magnetic sludge in the carbon crucible was kept at 1823?K (1550?°C) under an Ar atmosphere. The purity of the rare earth oxide phase was high and only a small amount of rare earth elements were contained in the alloy phase. We found that the melting temperature of the rare earth oxides is a crucial factor for separation efficiency in our proposed method.     

Influence of Lanthanum on Tribological Properties and Microstructure of Laser Clad B ＋ Fe ＋ Si Composite Coatings

The effects of rare earth ferrosilicon on the microstructure and anti-wear properties of laser-clad Fe-based alloy coating were investigated. The composition of Fe, B4C and rare earth ferrosillcon powders with different contents of lanthanum were clad onto a 45 # carbon steel substrate. Microstructural features, chemical compositions, phase structure,hardness, friction and wear properties by scanning electron microscopy (SEM), X-ray photoelectron microscopy (XPS),hardness tester, block-on-ring friction and wear tester of the clad coating were determined. Experimental results show that the friction coefficient of the clad coating doped with rare earth ferrosilicon is reduced while the wear resistance of clad coating doped with rare earth ferrosilicon is enhanced. When the content of lanthanum increases to 1.92%, the clad coating shows the best anti-wear ability, and as the content of lanthanum exceeds 1.92%, the wear weight loss increases quickly. The rare earth ferrosilicon to be doped in the clad coatings helps to disperse the boride phase (Fe2B, FeB, B4C)particles and refine the grain of boride phase. The enhancement of clad coating‘s wear resistance is due to the existence of dispersed boride phases.     

晶界扩散中Tb对烧结NdFeB磁体微观组织和磁性能的影响

通过晶界扩散技术提升烧结钕铁硼(NdFeB)磁体矫顽力的方法已获得广泛应用,为了研究重稀土磁粉对磁体综合磁性能的影响,本文采用喷涂扩散的方法将重稀土Tb含量为6.0%(质量分数)的磁粉作为复合扩散源的一部分进行晶界扩散并制备了高性能烧结NdFeB磁体。结果表明,当主扩散源占比为60%(质量分数)时,Nd₄₀Tb₆₀对应扩散磁体的矫顽力最高达到21.52 kOe,矫顽力增幅明显。经过微观组织结构和XRD表征分析,重稀土元素Tb沿晶界相扩散进入磁体内部的同时发生了晶格取代反应,可在晶粒表层生成磁晶各向异性场更强的(Nd,Dy/Tb)₂Fe₁₄B硬磁相,显著增强了磁体矫顽力。当主扩散源占比为20%、40%和80%(质量分数)时,Nd₈₀Tb₂₀,Nd₆₀Tb₄₀和Nd₂₀Tb₈₀对应扩散磁体的矫顽力增幅较小,其中Nd₈₀Tb₂₀扩散...     

ICP-AES分析轻稀土元素干扰校正研究

采用电感耦合等离子体原子发射光谱法定量分析轻稀土元素La、Ce、Pr、Nd、Sm,研究了轻稀土元素谱线干扰的校正,同时用正交设计实验对仪器工作条件进行了优化。在实验波长下,测得轻稀土元素的标准曲线、回归方程和相关系数,线性范围最大可达4个数量级。分别利用K矩阵校正测定稀土富渣、稀土混合物和铝合金样品,确定了稀土样品中轻稀土元素的含量。该方法无需对稀土元素进行分离。实现了稀土元素的快速、准确测定。     

Examination of Plasma Nitriding Microstructure with Addition of Rare Earths

Medium-carbon alloy steel was plasma nitrided with rare earths I_a, Ce and Nd into the nitriding chamber respectively. The nitriding layer microstructures with and without rare earths were compared using optical microscope, normal SEM and high resolution SEM, as well as TEM. It was found that the extent of the influence on plasma nitriding varies with different contents of rare earth. The effect of plasma nitriding is benefit from adding of Ce or Nd. The formation of hard and brittle phase Fe2-3N can be prevented and the butterfly-like structure can be improved by adding Ce or Nd. However, pure La may prevent the diffusion of nitrogen and the formation of iron nitride, and reduce the depth of diffusion layer.     

NdFeB-CeFeB互扩散对其组织和磁性能的影响

近年来由于Ce元素的价格优势和特殊性能,Ce掺杂NdFeB永磁体受到越来越广泛的关注。通过900℃均匀化处理、真空扩散焊接和900℃扩散处理制备了NdFeB-CeFeB扩散偶,探究了NdFeB和CeFeB互扩散对各自微观结构和磁性能的影响。扫描电子显微镜(SEM)和能谱分析(EDS)结果发现,随着900℃保温处理时间增长,组织中的第二相和孔洞逐渐消失。互扩散后Ce原子不能置换Nd2Fe14B中的Nd原子,而是主要被富Nd相捕获。而Nd原子扩散后置换Ce2Fe14B中的Ce原子,形成了(Nd0.615Ce0.385)2Fe14B和(Nd0.165Ce0.835)2Fe14B两相,证明(Nd1-xCex)2Fe14B化合物存在溶解间隙。两相区(Ce,Nd)FeB样品中Ce平均原子数约占总稀土原子数的69%,饱和磁化强度μ0MS约为1.46T,各向异性场μ0HA约为7.37T,其磁性能未因高Ce含量而大幅下降主要归功于两相组织的"核壳"结构和Nd对Ce价态的影响。     

有机次膦酸在硝酸体系下提取稀土研究

本文采用溶剂萃取法,用有机次磷酸萃取剂从富含稀土元素镧(La）、钕(Nd）、钇(Y)、铈(Ce）的硝酸溶液中提取稀土。选择盐酸为反萃剂。考察了酸度、萃取剂浓度、相比和萃取时间对萃取率和反萃率的影响,结果表明,二异丁基膦酸萃取稀土的最佳条件为：室温,酸度0.2mol/l,萃取剂浓度40%,A/O比1:5,萃取时间15min,镧（La）、钕（Nd）,铈（Ce）和钇（Y）分别为41.68%、81.30%、81.29%和100%。当利用盐酸作为反萃实验的反萃剂时其最佳条件为：室温,初始水相稀土溶液为0.3 mol/L,反萃剂盐酸为6 mol/L,负载有机相与反萃剂盐酸溶液的体积比为1:6,将反萃的震荡时间改变为5min,应用上述条件的镧(La）、钕(Nd）、铈(Ce）、钇(Y)的反萃率分别为92.45%、94.88%、95.76%、93.34%。有机次膦酸对稀土元素（La）、钕（Nd）、铈（Ce）和钇（Y）的萃取效率不同。钇的提取率高于镧、钕和铈。它是一种有机次膦酸,对轻稀土元素亲和力低,对重稀土元素亲和力强。     

织金含稀土磷矿酸法浸出性能及预处理优化工艺试验

硫酸、盐酸、磷酸和硝酸对原生织金磷矿的稀土组分浸出效率不理想,总稀土浸出效率不到36%。采用焙烧活化—硝酸氨水混合预浸出处理织金磷矿,最适宜条件下,CaO和MgO的浸出率分别为24.55%和19.75%,相应的P_2O_5和稀土元素(Y、La、Nd、Ce)损失率为11.25%和3.61%。所得精矿中,Y、La、Nd、Ce和P_2O_5实现了不同程度的富集。预处理精矿的浸出性能较原矿显著改善,硝酸体系下P_2O_5和稀土元素(Y、La、Nd、Ce)浸出效率提高了近40个百分点。     

Inversion Solidification Cladding of H90-Steel

The variation law of cladding thickness as well as the structures and properties of H90-steel clad strip produced by inversion solidification was studied. The interface bonding mechanisms were approached. It is found that the thickness of H90 cladding goes sequentially through the solidification growth stage, holding stage, and remelting stage, with an increase in immersion time. The higher the preheating temperature of the steel coil, the thicker is the maximum cladding thickness. Observation by using optical microscopy （OM） and the electron probe microanalyzer （EPMA） shows that the microstructure of H90 cladding is composed of equiaxed grains, and that interdiffusion between Cu and Fe at interface occurs but obvious diffusion of Zn and the intermetallic layer are not observed. The diffusion layer is thin and about 4 μm. Multipass small reduction cold rolling and repeated bending tests show that the interface is firmly bonded. Tensile test shows that the mechanical properties of the as-clad strips can meet the requirements of GB5213-2001 for the F-grade deep-drawing steel plate though there is a slight difference in the mechanical properties among the clad strips with different cladding thickness.     

Rare earth double sulfates from pre-concentrated bastnasite

A mixture of rare earth double sulfates was produced from a Turkish bastnasite-containing pre-concentrate (low grade concentrate) by sulfuric acid baking, subsequent water leaching and precipitation with sodium sulfate. The results of acid baking and leaching indicated that recoveries of rare earth elements up to 90% were readily obtained and the recovery of hydrofluoric acid as a by-product was also possible. Reasonable decontamination of the rare earth double sulfate salt from impurities such as Th, Fe, Al and Mg was possible by rapid precipitation at 50 °C using 1.25 times the stoichiometric amount of Na₂SO_4. The total rare earth double sulfate content (TREDS) was > 90% and analysed 17.3% La, 15.6% Ce, 3.2% Nd, 1.1% Pr, 0.3% Sm, 0.03% Eu, 0.01% Yb and 0.02% Y together with about 0.7% Ca, Fe, Al and other impurities.     

添加混合稀土的廉价Nd-Fe-B的研究

Nd-Fe-B永磁材料不仅具有很高的磁性能 ,而且不含资源紧缺的战略物资钴 ,因而其应用前景非常广阔。但人们希望其价格再降低 ,所以开发廉价磁体非常必要。可以通过降低原材料的成本 ,达到降低磁体成本的目的。实验对以混合稀土取代Nd Fe B合金中的钕的廉价铁基稀土永磁进行了研究 ,结果表明 :随着混合稀土的增加 ,磁性能有所下降 ,但在合金中添加少量的Al,Co,Nb ,可使磁体的磁感矫顽力 BHC上升 ,剩余磁感应强度Br、磁能积 (BH) m稍有下降。     

氧化铝赤泥盐酸浸出稀土元素研究

在用盐酸浸出氧化铝赤泥提取氧化钪的过程中,稀土元素镧,铈,钕也一同浸出,进入到浸出液中。研究了拜耳法赤泥盐酸浸出稀土元素镧,铈,钕的过程。研究了浸出温度、酸度、液固比和浸出时间对稀土元素浸出率的影响。研究结果表明,影响稀土浸出率的因素依次是浸出温度,盐酸浓度,配料液固比,和浸出时间。当接近沸点109℃浸出时,镧、铈、钕浸出率提高最快。盐酸酸度在4～5 mol.L-1时,浸出率升高较快,5～7 mol.L-1时,缓慢提高,当超过7 mol.L-1时,镧、铈、钕的浸出率基本不变化。当液固比为4.0时,镧、铈、钕元素的浸出率较低,仅为60%～75%之间,当液固比提高到5.0时,稀土元素的浸出率升高较快。随着浸出时间的延长,氧化稀土的浸出率从60～180 min时,缓慢提高,在180 min时达到最大值,超过180 min后,变化不大。在温度为沸点(109℃),液固比6.0,时间180 min。盐酸浓度7 mol.L-1的条件下浸出,赤泥中La,Ce,Nd的浸出率能达到95%以上。     

氮,氮,氮′,氮′-四辛基-3-氧戊二酰胺色谱柱分离-电感耦合等离子体质谱法测定混合稀土氧化物中重稀土

电感耦合等离子体质谱法(ICP-MS)测定稀土元素时,轻稀土元素Ce、Nd、Sm的氧化物等复合离子严重干扰重稀土元素Tb、Dy、Ho、Er的测定,因此对混合稀土中重稀土元素进行测定前一般需要先对其分离富集。实验在样品溶解后,将N,N,N′,N′-四辛基-3-氧戊二酰胺(TODGA)用硅藻土吸附后装柱,以0.1 mol/L HNO₃为样品溶液介质上柱,通过控制洗脱液的种类、酸度以及洗脱液流速,实现了轻稀土元素La、Ce、Pr、Nd与重稀土元素Tb、Dy、Ho、Er、Tm、Yb、Lu的分离和富集,建立了ICP-MS测定混合稀土氧化物中重稀土元素的方法。实验表明:控制洗脱流速为2.0 mL/min,用pH 2.0的HNO₃淋洗至淋洗体积约为500 mL,继续收集洗脱液,并用ICP-MS检测其中Nd₂O₃含量,直至洗脱液中Nd₂O₃的质量浓度小于200 ng/mL,可将轻稀土元素La、Ce、Pr、Nd及少量Y、Sm、Gd洗脱;再改用350 mL 1 mol/L HCl洗脱重稀土元素,可实现重稀土元素与La、Ce、Pr、Nd及部分Y、Sm、Gd的分离;通过选择¹⁵⁹Tb、¹⁶³Dy、¹⁶⁵Ho、¹⁶⁷Er、¹⁶⁹Tm、¹⁷²Yb、¹⁷⁵Lu为测定同位素可消除质谱干扰。将实验方法应用于混合稀土氧化物中重稀土元素的测定,加标回收率在93%～110%之间,相对标准偏差(RSD,n=8)在1.1%～10%之间。     

Extraction kinetics of neodymium from chloride medium using HEH/EHP saponified with magnesium bicarbonate solution

Magnesium bicarbonate solution is considered as an environmentally friendly extractant saponification agent for the solvent extraction of rare earth elements due to its advantage of minimum water pollution.In order to reveal the extraction regularity, optimize production-process and guide the use of this new extraction system, the extraction of Nd(Ⅲ) in chloride medium with HEH/EHP saponified by magnesium bicarbonate solution was investigated with the self-designed constant interfacial area cell. Besides, the effects of stirring rate, temperature, specific interfacial area and concentration of Mg-HEH/EHP on the extraction rate of Nd(Ⅲ) were systematically investigated. Results show that, the rate of extraction is governed by both diffusion and chemical reaction, and the extraction reaction takes place at the interface. The apparent activation energy of the extraction reaction is 16.88 kJ/mol. The corresponding rate equation is deduced. The mechanisms and rate-determining step are speculated based on interfacial reaction models, which is consistent with the experimental results.     

电感耦合等离子体原子发射光谱法测定镝铁电解粉尘中15种稀土元素

用硝酸和氢氟酸溶解试样,高氯酸冒烟除氟,在硝酸介质中用电感耦合等离子体原子发射光谱法(ICP-AES)测定了镝铁电解粉尘中La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y 15种稀土元素。为了提高高含量元素的测定准确度,在测定基体元素Dy时,采用铟作内标;为了消除基体效应对稀土杂质元素测定的影响,采用基体匹配的校准曲线。镝铁电解粉尘中铁含量很低(铁的质量分数不超过1%),对测定没有影响。实验方法测定了一镝铁电解粉尘样品,结果表明,La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Ho、Er、Tm、Yb、Lu和Y 14个稀土杂质元素测定值与ICP-MS的测定值基本一致,镝和14个稀土元素的合量与重量法测得的稀土总量吻合。     

Recycled Nd-Fe-B sintered magnets prepared from sludges by calcium reduction-diffusion process

Environmental friendly recycling process for Nd-Fe-B sintered magnet sludges generated in the manufacturing process, which contain large amount of rare earth, including Nd, Pr and Dy, is badly needed so far. In present study, we have developed an effective route to obtain recycled sintered magnets from Nd-Fe-B sintered magnet sludges by calcium reduction-diffusion (RD) process. Compared to conventional recycling process, our research is focused on recovering most of the useful elements, including Nd, Pr, Dy, Co, and Fe together instead of just rare earth elements. To improve the recycling efficiency and reduce pollution, the co-precipitating parameters were simulated and calculated using MATLAB software. Most of useful elements were recovered by a co-precipitation method, and the obtained composite powders were then directly fabricated as recycled Nd-Fe-B powders by a calcium reduction-diffusion (RD) method. The recovery rates are 98%, 99%, 99%, 93%, and 99%, for Nd, Pr, Dy, Co, and Fe, respectively. The amount of useful elements contained in the recovered composite powders is greater than 99.71 wt%. The process of RD for synthesizing Nd₂Fe₁₄B and subsequently removing CaO was thoroughly investigated. Furthermore, the recycled Nd-Fe-B magnet exhibits a remanence of 1.1 T, a coercivity of 1053 kA/m, and an energy product of 235.6 kJ/m³, respectively, indicating that recycled Nd-Fe-B sintered magnet was successfully recovered from the severely contaminated sludges via an effective recycling route.     

氧化铁复合颜料表面包覆层结构的X射线光电子能谱研究

表面包覆无机膜是改善粒子性能的重要方式,实验在铁红超细微粒子中掺杂稀土元素Nd和SiO₂,形成氧化铁复合颜料,采用X射线光电子能谱(XPS)研究表面无机膜的成分、化学状态及其含量,推测Fe₂O₃复合颜料表面包覆无机膜及稀土掺杂涂层的情况。结果表明,根据O 1s和Fe 2p谱图分析Fe-O键反应弱,推知Fe₂O₃粒子表面包覆情况良好,根据Si 2p和Nd 3d、Nd 4d化学位移,推测Nd、Si原子可能进入Fe₂O₃晶格,取代了O、Fe原子,降低了Fe-O的比例,重新结合形成新键,使复合粒子表面形成Nd-O-Si键,稀土原子成功掺杂在Fe₂O₃粒子表面包覆的SiO₂无机膜中。因稀土元素且有丰富的谱线特征,使制备的颜料色彩效果更佳,提高了粒子的性能。     

稀土对方坯连铸保护渣理化性能影响的研究

通过实验室和现场试验研究，得出对结晶器喂稀土丝后，稀土对高碳钢、低碳钢保护渣使用性能有一定影响。建议尽快进行稀土处理方坯低碳钢专用保护渣的研究开发工作。     

Nd(III)在NaF-KF熔盐钨电极上电化学行为

钕铁硼磁体中稀土元素钕占据较大比重,从钕铁硼废料回收稀土有重大意义。为进一步了解钕在高温下氟化物熔盐的行为,本文在1 063 K采用NaF-KF(摩尔比2:3)电解质体系,加入质量分数为1%的NdF₃,以Pt为参比电极,钨棒为对电极,用循环伏安法等电化学暂态测试研究了Nd(III)在惰性钨电极上的电化学过程,探究Nd(III)的还原机理。结果显示:Nd(III)于NaF-KF-NdF₃熔盐中在惰性钨电极上的电化学还原过程是受扩散控制的不可逆的一步反应:Nd(III)+3e-=Nd,1 063 K时循环伏安法得到Nd(III)的扩散系数为2.107×10-5 cm2/s,钕的成核机制为瞬时成核。      

Synthesis mechanism of Sm₂Fe₁₇ alloy produced in reduction-diffusion process

Sm2Fe17 alloy was the precursor of Sm2Fe17Nx magnetic materials.Reduction-diffusion(R/D) method was a new preparation process for the Sm2Fe17 alloy,and had been widely employed as a new preparation method for rare earth-transition metal intermetallic compounds.In this text,thermodynamics and kinetics for the synthesis of the Sm2Fe17 alloy by reduction-diffusion(R/D) method in the Ca-Sm2O3-Fe system were analyzed.The related synthesis mechanism of this reaction was investigated in detail by means of scanning electron microscope(SEM).The results showed that the thickness of the Sm2Fe17 alloy layer versus the reaction time could be fit by the parabola law,and its growth model was determined to be:(L0-L)2=43.848 t,the diffusion of Sm into Fe proceeded with the formation of the Sm2Fe17 phase from the very beginning of the reaction,and rich samarium phases,such as SmFe2 and SmFe3,were not formed,and the rate-determining step of the R/D reaction was found to be the peritectic reaction between liquid samarium and solid iron.