Reduction leaching of rare earth from ion-adsorption type rare earths ore with ferrous sulfate

The practice of in-situ leaching of the ion-adsorption type rare earths ore with ammonium sulfate could only leach most of rare earth in ion-exchangeable phase,but not the colloidal sediment phase.Therefore,the reduction leaching of rare earth from the ion-adsorption type rare earths ore with ferrous sulfate was innovatively put forward.The soak leaching process and the column leaching process were investigated in the present study.It was determined that ion-exchangeable phase could be released,and part of colloidal sediment phase rare earth could be reduction leached by the cations with reduction properties.The mechanism of reduction leaching was discussed with the Eh-pH diagram of cerium.Moreover,the stronger reduction of reductive ions,the greater acidity of leaching agent solution,and the higher reductive ion concentration,could result in the higher rare earth efficiency and the bigger cerium partition in the leaching liquor.In the ferrous sulfate column leaching process,the rare earth leaching rate and the rare earth efficiency were a little higher than with(NH_4)_2SO_4 agent,and the rare earth efficiency and the partitioning of cerium in leaching liquor could be about 102% and 5.31%,respectively.However,the ferrous sulfate leaching process revealed some problems,so compound leaching with magnesium sulfate and a small amount of ferrous sulfate was proposed to an excellent alternative leaching agent for further studies,which may realize efficiency extraction and be environment-friendly.     

Coordination-reduction leaching process of ion-adsorption type rare earth ore with ascorbic acid

The magnesium sulfate(MgSO₄)-ascorbic acid(Vc) compound leaching technique can extract rare earth elements(REEs) existing in ion-exchangeable phase and colloidal phase from ion-adso rption type rare earth ore through the synergy effect of coordination and reduction,but its reaction process and mechanism remain unclear.In this paper,the coordination-reduction leaching mechanism was analyzed from the perspectives of leaching thermodynamics and kinetics,which provide theoretical guidance...     

Mineral properties and leaching characteristics of volcanic weathered crust elution-deposited rare earth ore

Weathered crust elution-deposited rare earth ore is an important resource of rare earths, including grantic weathered crust elution-deposited rare earth ore and volcanic weathered crust elution-deposited rare earth ore. The development condition of the weathered crust, weathering degree and mineral composition of these ores will be different because of the differences between their parent rocks and weathered crust causes of mineralogy path. Therefore, mineral properties and leaching characteristics of volcanic weathered crust elution-deposited rare earth ore from Chongzuo(CZ), Guangxi province were investigated. It was found that the CZ rare earth ore was a typical mid-yttrium and rich-europium ore, with the overall rare earth(REE) grade in ion-exchangeable phase of 0.15%. Partide size classification showed that finer particle had a higher REE grade. Column leaching tests showed that the leaching efficiency of REE was above 94% with leaching agent concentration of 0.20 mol/L, liquid-solid ratio of 4:3, flow rate of 0.60 mL/min, and initial pH value around 5.67. Compared to ammonium sulfate leaching, magnesium sulfate leaching was advantaged by nearly zero ammonia nitrogen emission while their REE leaching was almost equivalent.     

超声波强化浸取离子型稀土矿中稀土

利用超声波的空化作用可有效强化南方离子型稀土矿中稀土的浸出,从而提高稀土浸出率并缩短矿物中稀土总量的分析时间。在20 g/L的硫酸铵浸矿液中超声浸矿30 min,可使离子型稀土的浸出率达99%以上,而传统搅拌法需4 h,甚至浸取过夜。超声法与搅拌法对干扰杂质铁、铝的浸出率相近,加入乙酰丙酮及磺基水杨酸等掩蔽剂后不影响EDTA滴定稀土时的终点判断,且测定结果与电感耦合等离子体发射光谱法测定结果一致性好。     

离子型稀土不同浸出剂柱浸对比试验

针对离子型稀土原地浸出工艺现有氨氮污染问题,考察镁盐、铝盐等非铵浸出剂对稀土浸出过程的影响。以赣州稀土矿样为研究对象,选择硫酸镁与硫酸铵通过柱浸的方式进行对比试验,同时考察铝盐与铵盐、镁盐联合浸出效果的影响,测定浸出液成分,分析不同浸出剂浸出效果的差异。结果表明：相同质量分数的硫酸铵和硫酸镁浸出效率相当,硫酸铵可达91.37%,硫酸镁可达89.22%;添加铝盐后的稀土浸出率仅76%左右,铝盐的添加不能促进稀土浸出效率的提升;铵盐柱浸顶水洗涤后铵根离子可降低至76 mg/L,镁盐柱浸顶水洗涤后镁离子可降低至27 mg/L,镁离子比铵根离子更容易洗涤去除。硫酸镁作为浸出剂能够从根本上解决离子型稀土矿山氨氮污染问题。     

Insight into leaching of rare earth and aluminum from ion adsorption type rare earth ore: Adsorption and desorption

Clay minerals are inferred to be the primary host materials for ion-exchangeable rare earth in ion adsorption type rare earth ore(IAREO).During the rare earth leaching process,the adsorption and desorption reactions of the cations controlling the leaching process continue to occur at the clay minerals-leaching agent solution interface.In order to understand the leaching mechanism and behavior of rare earth and co-leached aluminum,adsorption,competitive adsorption,and desorption experiments were ...     

某离子型稀土矿浸出试验

以中国南方地区某离子型稀土矿为研究对象,采用搅拌浸出和柱浸的方式,研究不同条件下矿样中稀土及杂质元素的浸出情况,为离子型稀土矿产资源的绿色高效开采提供参考。结果表明,浸出液固比对离子相稀土浸出率影响较大,浸出时间影响较小,离子相稀土浸出过程时间短,反应迅速;柱浸过程中离子相稀土流出速率最快,达到平衡时间短,杂质元素前期浸出浓度高,后续拖尾严重;离子相稀土浸出率随着样品深度的增加不断降低,符合南方离子型稀土成矿规律;硫酸铵浸出过程中铵根离子损失量较大,最低损失率超过11.31%,硫酸根不参与金属离子的交换反应过程,回收率最高可达99.22%。     

镁钙铵系浸取剂对离子吸附型稀土矿区土壤生态影响初探

离子吸附型稀土矿富含宝贵的中重稀土战略资源,工业开采过程产生的氨氮污染问题长期备受关注。分别以硫酸镁、氯化钙和硫酸铵柱浸模拟离子吸附型稀土矿浸取尾矿,以中黄13大豆为供试作物,开展了室外盆栽试验,探究其对离子吸附型稀土矿区土壤的生态影响。结果表明,与采用铵浸尾矿种植相比,采用镁浸或钙浸尾矿种植的豆苗株高相当或更高,叶片的叶绿素含量更高或相当,根系生长正常,主根明显,侧根茂盛,且地径明显更粗,这可能与镁、钙等能直接参与叶绿素合成、加速糖分运输、改善土壤板结等有关。与采用硫酸铵浸取剂浸矿相比,采用硫酸镁、氯化钙浸取剂浸矿对离子吸附型稀土矿区土壤的生态影响更小,这也为离子吸附型稀土矿绿色开采和浸矿场地污染防治指明了发展方向。     

离子型稀土矿硫酸镁柱浸过程中水、稀土和硫酸镁的平衡研究

采用柱浸方法研究无氨浸矿剂硫酸镁浸出离子型稀土矿,考察了浸矿过程中H2O、REO、Mg2+、SO2-4走向。结果表明,每千克稀土原矿吸水量约为344mL,稀土元素浸出率在99%以上,全过程损失率仅为0.045%,有0.24%的镁离子残留于矿体中,浸出液中镁离子总量增加4.7%,平衡率为98.76%,硫酸根总体升高0.52%。硫酸镁作为浸取剂,杂质Fe、Si的浸出率分别由硫酸铵浸矿时的0.435%、0.703%降低到0.03%、0.13%,杂质Al的浸出率基本保持不变。     

稀土矿开发过程污染物对土壤生物有效性研究进展

针对稀土矿采用原地浸矿工艺开采稀土过程中大量含有稀土、硫铵以及其他污染物的浸矿残留液进入周边农田土壤环境的现状,总结了国内外不同污染物对土壤生物有效性的研究进展及评价方法,为研究稀土及浸矿剂硫铵对土壤蚯蚓等生物有效性的课题提供理论基础.旨在通过探讨稀土元素及浸矿剂硫铵对土壤生物产生的影响,为稀土矿开发活动破坏周边农田土壤环境的生态评价提供实验依据及参考信息.      

Separation and recovery of associated rare earths from the Zhijin phosphorite using hydrochloric acid

The separation and extraction of associated rare earths from the Zhijin phosphorite mine is of great interest. Based on previous studies, the hydrolysis of phosphate ore using hydrochloric acid was systematically studied through extensive testing. Experiments were conducted to separate and recover the rare earths from the hydrolysis solution. Kinetic studies on the acidolysis of phosphorite using hydrochloric acid show that the use of hydrochloric acid in the acidolysis of phosphorite is mainly controlled by a chemical reaction and is also a diffusion-controlled reaction. When 210 L of HCL per 100 kg of phosphorite was used at 30 ℃ for 360 min, 96.1% of the P_2 O_5 and 95.0% of the rare earths are leached from the phosphorite. After defluorination and purification, the pH of the phosphate-acid solution is adjusted to 2.1 using sodium hydroxide, and a rare earth concentrate with rare earth content of 1.76 wt%is obtained; i.e., 90.1% of the rare earths are recovered. The rare earth content is increased to more than5 wt% through multiple enrichment processes, with a total yield of 59.5%.     

Preparation of crystalline mixed rare earth carbonates by Mg(HCO_3)_2 precipitation method

In acid treatment technology of Baotou mixed rare earth ore,large quantities of ammonia-nitrogen wastewater are produced in the step of ammonium bicarbonate precipitation to transform rare earth sulfate.In this paper,we adopted a green precipitant magnesium bicarbonate(Mg(HCO_3)_2) to substitute ammonium bicarbonate to eliminate ammonia-nitrogen pollution.The effects of n(HCO_3~-):n(RE~(3+)),aging temperature and aging time on the crystallization using Mg(HCO_3)_2 precipitation method were investigated.The results indicate that the rare earths could be completely recovered when n(HCO_3~-):n(RE~(3+)) is higher than 3.15:1.The crystal water content of rare earth carbonates is affected by the aging temperature.The precipitate has a bad filterability when the aging temperature is over 40℃.This can be attributed to the less crystallized water molecules of the hydrated rare earth carbonate precipitation.The mixed rare earth carbonates are prone to be crystalline,and have a good filterability at aging temperatures below 40℃.Meanwhile,the evolution mechanism of crystalline mixed rare earth carbonates is reasonably deduced,the amorphous rare earth carbonates are first dissolute and then recrystallized.Under the optimized aging conditions,the purity of the crystalline precipitate meets the requirements of the fine product standard(GB/T 16479-2008).The filtrated could be used to produce Mg(HCO_3)_2,thus to realize the recycling of magnesium sulfate.     

Study on preparation and application of novel saponification agent for organic phase of rare earths extraction

In view of the problem of ammonia-nitrogen wastewater pollution in rare earths extraction and separation, the novel saponification agent of organic phase, which is magnesium bicarbonate solution, was prepared with the natural rich and cheap dolomite as raw material through carbonation process. The behavior and purification of main impurities ions in the carbonation process as well as the application effect of the novel saponification agent in the extraction and separation was researched. The results showed that the concentration of Fe, Al, Si impurities ions was less than 5 ppm in the saponification agent through the development of effective removal technology, respectively. When the novel saponification agent was used in the extraction and separation, magnesium utilization rate was more than 95%, and rare earths extraction rate above 99.5% has achieved. Therefore, the technology could replace ammonia-water to saponify the organic phase in rare earth extraction and separation process.     

EDTA滴定法测定稀土铝中间合金中稀土总量

准确测定稀土铝中间合金中稀土总量,对于有效控制稀土铝中间合金的生产技术和产品质量具有重要意义。用400g/L氢氧化钠溶液溶解试样,此时,稀土与氢氧化钠反应生成氢氧化稀土沉淀,而铝与氢氧化钠反应后以偏铝酸根的形式留在了试液中,过滤,实现了铝与稀土元素的分离;用盐酸溶解沉淀,加入氢氟酸,此时稀土和氢氟酸反应生成氟化稀土沉淀,而铁与氢氟酸反应形成络合物留在溶液中,过滤,实现了干扰元素铁与稀土元素的分离;加入盐酸和高氯酸溶解沉淀,用抗坏血酸还原残留铁(III),乙酰丙酮溶液掩蔽残留的少量干扰元素铝,控制pH 5.5,以二甲酚橙作指示剂,用EDTA标准溶液滴定至溶液由红紫色变为亮黄色即为终点,建立了EDTA滴定法测定稀土铝中间合金中稀土总量的方法。将实验方法用于稀土铝中间合金(镧铝、钐铝、铒铝、钇铝)试样中稀土总量的测定,并在试样中分别加入不同量的于950℃马弗炉中灼烧过的高纯氧化镧、高纯氧化钐、高纯氧化铒和高纯氧化钇试剂进行加标回收试验,结果的相对标准偏差(RSD,n=11)不大于0.30%,加标回收率为99.6%~100.4%。选取镧铝、钐铝试样,按照实验方法测定其中稀土总量,并采用国标GB/T 31966—2015中的草酸盐重量法进行方法比对试验,测定结果基本一致。     

非离子型表面活性剂对风化壳淋积型稀土矿浸出过程的影响

为了缓解风化壳淋积型稀土矿浸取过程存在的浸取周期长、浸出剂用量大和稀土拖尾等问题,以非离子型表面活性剂为助浸剂,氯化镁为浸出剂,对稀土浸出过程进行研究,研究复配浸出剂溶液性质,分析浸矿前后矿物粒径分布,探讨表面活性剂的促渗机理。研究结果显示,加入表面活性剂后,稀土浸出率提高,渗透速度加快,溶液的表面张力和接触角均减小,黏度增大,矿物颗粒的中值粒径明显减小,矿物表面Zeta电位增大,其中加入吐温40后稀土浸出率提高至86.38%,表面张力减小19.00%,接触角减小53.19%,溶液黏度减小4.29%,溶液性质变化最大。加入表面活性剂后可使溶液更容易润湿矿物,进入孔隙的阻力变小,扩散层厚度减小,黏土矿物的膨胀受到抑制,使得溶液浸出稀土的效果更好,其中吐温40对溶液浸出稀土的渗流效果影响最大,助渗效果最好。     

聚乙二醇对风化壳淋积型稀土矿浸出的影响

针对氯化铵作为浸取剂浸取风化壳淋积型稀土时,稀土浸取速率较低和浸出周期长等问题,使用聚乙二醇(PEG)为添加剂,通过柱浸试验模拟工业生产中的原地浸出工艺,探究不同聚合度的聚乙二醇对稀土矿渗透性和稀土浸出的影响。结果表明,聚乙二醇400、聚乙二醇1000和聚乙二醇4000溶液在稀土浸出过程中表现出较好的渗透效果。采用质量分数2.00%的聚乙二醇400、聚乙二醇1000、聚乙二醇4000分别与0.20mol/L的氯化铵复配,复配浸取剂溶液在稀土矿样中的渗透速率随着水力梯度的增大呈线性增大,符合达西定律。PEG400+NH_4Cl、PEG1000+NH_4Cl、PEG4000+NH_4Cl以及NH_4Cl溶液的稀土浸出率分别为82.61%、89.12%、70.67%和88.06%,且当聚乙二醇1000作为助浸剂时,渗流速率最大,渗透效果最佳。添加了聚乙二醇1000的复配浸取剂溶液,在浸取风化壳淋积型稀土矿中稀土的反应过程符合内扩散动力学模型。研究结果对提升复配浸取剂溶液在稀土矿体中的渗流速率有重要意义。     

Extraction and separation of yttrium from other rare earths in chloride medium by phosphorylcarboxylic acids

Two phosphorylcarboxylic acids, 3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid (PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid (PPPA), were synthesized for separating yttrium from other rare earths in the chloride feed of ion-adsorption type rare earth concentrate. The effect of the factors such as pH_1/2, temperature, saponification degree and phase modifiers was investigated. The separation efficiencies of PPA and PPPA are obviously better than the typical extractants such as sec-octylphenoxy acetic acid (CA-12) and naphthenic acid (NA). The extraction process of rare earths by PPA and PPPA is a cation exchanging reaction, which is similar to those of CA-12 and NA. The loaded rare earths in both PPA and PPPA systems can be effectively back-extracted by 0.5 mol/L HCl or higher concentration. A cascade extraction process for separating yttrium from other rare earths was developed using PPPA as the extractant. The yttrium product with the purity of 97.20 wt% was obtained by 35 stages of extraction and 12 stages of scrubbing.     

离子型稀土矿浸出过程主要物质浸出规律研究

采用柱浸法研究硫酸铵浸取离子型稀土矿过程中水、稀土、硫酸铵及其他杂质离子的浸出规律. 研究表明,离子型稀土矿矿土对水有较强的吸附能力,浸矿后,矿土的含水率由17.74 %增加到33.7 %.浸出过程中,稀土浸出率可达99.98 %,杂质中Al3+浸出量比较大,SiO₃2-浸出量较小,而Fe3+几乎不浸出,各离子的浸出先后顺序为:SiO₃2-、RE3+、Al3+、Fe3+,杂质Al3+的浸出略滞后于稀土的浸出. Al3+、Fe3+浓度达到峰值时,pH值最低,随着浸矿剂和顶水的加入,浸出液的pH值开始上升,直至达到硫酸铵溶液的pH值和顶水的pH值.      

Non-ammonia enrichment of rare earth by magnesium oxide from rare earth leaching liquor in magnesium salt system

In order to solve the problem of ammonia-nitrogen pollution in the enrichment process of the ionadsorption type rare earth ore,the technology of non-ammonia precipitation with magnesium oxide precipitant was carried out.It is determined that the rare earth precipitation efficiency is 99.6% and the purity of rare earth concentrates is only 85.89 wt%under the optimum precipitation conditions.And the contents of MgO,SO_3 and Al_2O_3 in the rare earth concentrates are 5.12 wt%,6.77 wt%and 1.78 wt%,respectively.Furthermore,the thermo-decomposition process of precipitates was investigated by TGDSC,XRD and FI-IR.The thermal decomposition process consists of two stages:the dehydration of rare earth hydroxide and alkaline rare earth sulfate within 900 ℃ and the thermal decomposition of RE_2O_2SO_4 at 900-1300 ℃.Therefore,a high-temperature calcinations method for removing SO_3 from precipitates is proposed.When the precipitates are calcined at 1300 ℃ for 2 h,the rare earth concentrates with a purity of 92.03 wt%can be acquired.Moreover,the content of SO_3 in the concentrate is only 0.46 wt%.In the MgO precipitation and high-temperature calcinations process,the raw material cost is low and the quality of rare earth concentrates is acceptable.It could have great significance for nonammonia enrichment of rare earth from the rare earth leaching liquor,and finally solve the problem of ammonia nitrogen in the extraction process of the ion-adsorption type rare earth ore within magnesium salt system.     

稀土资源收储专项储备量的确定

文中梳理了定性确定稀土资源储备规模的文献资料,利用现实可提供储备量与预测趋势可提供储备量的波动关系以及储备量模拟模型,定量化计算了稀土资源收储储备量,以2000-2011年的稀土资源产、销、存数据为例,设计了稀土资源可提供储备量波动范围分别为0%、5%和10%的3个方案,模拟计算了3个方案的年最大储备量、最小储备量、专项储备量和绝对储备量,初步确定了2012年中国稀土资源收储的专项储备量.国家储备进行储备决策时,可以根据国家财政状况、国内外经济景气状况和稀土产业发展状况,选择实施高度储备、中度储备还是低度储备,并在不同储备思路指导下动态调节专项储备量.