田菁胶助浸低品位风化壳淋积型稀土矿研究

针对低品位风化壳淋积型稀土矿渗透性存在的问题,采用田菁胶作助浸剂,利用其促渗性能来提高风化壳淋积型稀土矿浸取效率,通过试验考查了田菁胶浓度、浸取剂浓度、浸取流速、浸取固液比对稀土浸取效果的影响.结果表明,田菁胶助浸使稀土的浸取率由87.05 %提高至94.17 %,同时还减少32.56 %浸取剂用量,有效地提高了风化壳淋积型稀土矿的浸取效率.      

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.     

Leaching hydrodynamics of weathered elution-deposited rare earth ore with ammonium salts solution

In order to reveal the permeability rule of leaching agent solution and the effects of anions in the leaching process of weathered crust elution-deposited rare earth(RE) ores, the effects of ammonium concentration, temperature, particle size and porosity on the permeability were discussed in detail with(NH_4)2_SO_4, NH_4Cl and NH_4NO_3 as the leaching agent. It was found that the permeation velocity of ammonium salts increased linearly with the increase of hydraulic gradient. The seepage of ammonium salts solution in the RE ores followed Darcy's law and displayed a laminar flow. The properties of the leaching agent solution and RE ores were the main factors that affect the permeability of RE ores. With the decrease of ammonium concentration and increase of temperature, the viscosity of solution decreased and the permeability coefficients of RE ores increased. And the effects of temperature on the viscosity and permeability were larger than ammonium concentration. The permeability of RE ores became worse with the decrease of particle size and porosity, and the particle size played a more important role compared with porosity. The permeability coefficient of RE ores increased and the viscosity of ammonium salts solution decreased in the order of(NH_4)_2SO_4, NH_4Cl and NH_4NO_3, implying that the penetrating power of anions increased in the order of SO_4~(2-), Cl~- and NO_3~-. The results may play a vital role in improving the permeability of weathered crust elution-deposited RE ores.     

不同孔隙比下风化壳淋积型稀土矿强度特性

风化壳淋积型稀土开采过程中,孔隙比为影响浸矿效果和矿体稳定性的关键因素.为探索不同孔隙比下风化壳淋积型稀土矿强度特性变化,选取6组重配比的稀土矿样,对不同孔隙比矿样进行了直接剪切实验,探讨孔隙演化对矿体抗剪强度的作用规律,揭示孔隙比对黏聚力和内摩擦角的影响机制.研究表明:不同孔隙比非饱和稀土矿对应着不同的剪切强度,基于试验数据发现剪应力与剪位移呈"类抛物线"变化,并建立了孔隙比与抗剪强度指标的关系模型.机制分析认为,随着孔隙比的增大,结合水膜效应逐渐弱化,粒间接触点数目也随之减少,使矿体抗剪强度减小.      

风化壳淋积型稀土矿原地浸矿负压收液研究

为了探求风化壳淋积型稀土矿原地浸取工艺中负压收液的可能性及其效果,通过浸矿剂渗透规律及负压收液机理的研究,对负压收液影响因素及边界范围、负压收液试验方法、负压值与收液率的关系、负压收液工艺及其抽取方式进行了探究.优化了收液方式和条件,得出了收液率与负压值基本上呈线性关系,最佳的抽液方式为停机时间10 min,开机时间50 min,三孔联抽,负压值维持在2.66×104Pa以上.随后进行了万吨级矿块工业试验,以进一步验证优化条件,获得了理想的试验结果及技术经济指标,其中REO浸取率达77.5%.     

风化壳淋积型稀土矿的基础研究

文章评述了40年来风化壳淋积型稀土矿的基础研究,包括矿床的成因及特征、稀土矿物的组成及性质,稀土与黏土矿物的关系、稀土在黏土矿物中的吸附及迁移理论,论述了风化壳淋积型稀土矿的稀土元素配分的特征及四大效应,并探讨了稀土浸出机理和风化壳淋积型稀土矿稀土浸取的三代工艺,提出了风化壳淋积型稀土矿基础研究和浸出工艺的发展方向及亟待解决的问题.      

风化壳淋积型稀土矿浸取过程中基础理论研究现状

对风化壳淋积型稀土矿浸取过程中的浸取水动力学、原地浸出渗流规律、浸取稀土动力学、浸取铝动力学、浸取传质浸取过程选择性等基础理论现状进行了概括和分析.指出了目前浸取过程中存在的一些问题和面临的挑战,特别指出应在浸铝浸取动力学过程研究、浸取过程强化研究、堆浸、原地浸出基础理论研究方面有待进一步加强.      

复合铵盐浸出风化壳淋积型稀土矿的研究

采用复合铵盐作浸出剂浸出风化壳淋积型稀土矿中的稀土。考察浸出剂的配比、浓度、液固比、流速、pH等因素对稀土浸出率的影响。结果表明,NH4Cl、NH4NO3、(NH4)2SO4质量比为4∶5∶6的复合铵盐浸出剂为最佳组合;液固比越大、流速越慢,浸出率越高;当浸出剂浓度为10g/L、pH=3.5时浸出效果最好。     

风化壳淋积稀土矿浸取动力学基础理论研究

风化壳淋积型稀土开采先后经历了池浸、堆浸和原地浸矿,目前采用原地浸矿法.研究风化壳淋积型稀土浸取动力学有助于从本质上提高浸矿效率和资源回收率,为高效、科学开采风化壳淋积型稀土矿提供理论依据,进一步完善风化壳淋积型稀土的原地浸出理论和技术.为此对风化壳淋积型稀土矿浸取动力学基础理论进行研究,并针对现有浸矿工艺,指出了影响浸取效率的因素,提出了提高风化壳淋积型稀土浸取速度的方法与措施.      

离子型稀土矿抑杂浸出中抑铝剂的研究

研究了在抑杂浸出过程中添加抑铝剂对稀土浸出的影响,筛选出了适宜的抑铝剂．所筛选出的抑铝剂能适应于我国南方不同类型离子型稀土矿,抑铝剂的添加几乎不影响稀土的浸出率．通过抑杂浸出得到的浸出液中铝离子含量小于2mg／L,去除率达到98％以上,铁离子含量小于0．3mg／L,该浸出液无需净化直接用碳酸氢铵沉淀得到的碳酸沉淀稀土符合生产质量要求．稀土产品质量达到国内现行标准,有效地简化了生产流程,并能减少5％-15％的稀土损失．     

风化壳淋积型稀土矿浸出液沉淀浮选溶液化学分析

通过对风化壳淋积型稀土矿浸出液沉淀浮选进行溶液化学研究,探讨了体系pH、沉淀剂及浮选剂对沉淀浮选的影响.结果表明,风化壳淋积型稀土矿浸出液杂质可通过优先沉淀浮选以氢氧化物或焦磷酸盐或聚磷酸沉淀形式全部有效除去,最后将优先沉淀浮选除杂后浸出液中和提高pH值,再用沉淀浮选方法有效提取稀土.     

Anti-swelling mechanism of DMDACC on weathered crust elution-deposited rare earth ore

In order to inhibit the swelling of the clay minerals in the in-situ leaching process of weathered crust elution-deposited rare earth ores (WCE-DREO), diallyl dimethyl ammonium chloride (DMDACC) was introduced as an anti-swelling agent and combined with (NH₄)₂SO₄ as a novel composite leaching agent. It can be found that the novel composite leaching agent exhibits a good anti-swelling performance and leaching capacity of rare earth, and has great potential on the actual exploitation of WCE-DREO. The anti-swelling mechanism of DMDACC was studied by characterization analysis. The results show that DMDACC with positive charges can be adsorbed on the clay particles by the electrostatic attraction and hydrogen bonds, and neutralize the negative charge of the clay particles. The double electrical layers are suppressed and the repulsion force between clay sheets decreases. It causes the clay particles prone to aggregate. Moreover, DMDACC can enter the interlayer and expel out the water molecules in interlayer. The interlayer spacing is decreased and the hydration swelling of the clay particles is weakened. It can provide a theoretical basis for the development of novel anti-swelling agents.     

Leaching kinetics of ionic rare-earth in ammonia-nitrogen wastewater system added with impurity inhibitors

Ammonia-nitrogen wastewater is produced during the dressing and smelting process of rare-earth ores.Such wastewater includes a very high concentration of NH4＋, as well as other ions（e.g., NH4＋, RE3＋, Al3＋, Fe3＋, Ca2＋, Cl–, and Si O32–） with a p H of 5.4–5.6.Its direct discharge will pollute, yet it can be recycled and used as a leaching reagent for ionic rare-earth ores.In this study, leaching kinetics studies of both rare earth ions and impurity ion Al3＋ were conducted in the ammonia-nitrogen wastewater system with the aid of impurity inhibitors.Results showed that the leaching process of rare-earth followed the internal diffusion kinetic model.When the temperature was 298 K and the concentration of NH4＋ was 0.3 mol/L, the leaching reaction rate constant of ionic rare-earth was 1.72 and the apparent activation energy was 9.619 k J/mol.The leaching rate was higher than that of conventional leaching system with ammonium sulfate, which indicated that ammonia-nitrogen wastewater system and the addition of impurity inhibitors could promote ionic rare-earth leaching.The leaching kinetic process of impurity Al3＋ did not follow either internal diffusion kinetic model or chemical reaction control, but the hybrid control model which was affected by a number of process factors.Thus, during the industrial production the leaching of impurity ions could be reduced by increasing the concentration of impurity inhibitors, reducing the leaching temperature to a proper range, accelerating the seepage velocity of leaching solution, or increasing the leaching rate of rare earths.     

A Review of Ammoniacal Thiosulfate Leaching of Gold: An Update Useful for Further Research in Non-cyanide Gold Lixiviants

This literature review provides an update of ammoniacal thiosulfate as a potential lixiviant of gold, the history of thiosulfate leaching and recent progress on thiosulfate leaching of gold, as well as the production, oxidation, and stabilization of thiosulfate. The leaching results of different types of gold ores including oxide, sulfide, carbonaceous, and refractory ores/concentrates and the fundamentals relevant to the oxidation of pure gold are summarized. The factors affecting gold leaching such as pH, temperature, and oxidants in leaching solutions, reagent concentrations, and foreign ions are presented to update the current understanding on gold dissolution in a Cu(II)-NH₃-S₂O₃^2-system.     

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。     

风化壳淋积型稀土矿提取工艺绿色化学内涵与发展

详细评述了风化壳淋积型稀土矿提取工艺绿色化学内涵和发展过程,指出了存在的问题,展望了今后的发展趋势。     

Behavior of leaching and precipitation of weathering crust ion-absorbed type by magnetic field

With weathering crust Ion-Absorbed Type Rare Earth （IATRE） ores in southern Jiangxi as an example, rare earth percolation leaching and leaching solution precipitation process research were carried out under conditions of magnetic field. The effect on the rare earth leaching process such as magnetic field strength, magnetization time, magnetization manner, and other factors were discussed. The effect on the mother rare earth liquor sedimentation rate, purity, and crystallization behavior such as magnetic field strength, magnetization time, and magnetization manner were investigated. Leaching and precipitation mechanism of magnetization on IATRE were analyzed. The results showed that the magnetic treatment can improve leaching rate of weathering crust IATRE and the sedimentation rate, and reduce consumption of reagents.     

风化壳淋积型稀土矿矿石性质及稀土在各粒级上的分布

研究了风化壳淋积型稀土矿矿石性质及稀土在各粒级上的含量。采用热重分析、EDTA容量法、紫外分光光度法、原子吸收分光光度法、甲醛容量法等测试手段,对矿石的多水性、吸附稀土离子的稳定性、原矿的缓冲性、吸附离子的可交换性这四大物理化学性质进行了验证,对稀土在各粒级上的含量进行了测定,为进一步合理利用该矿石资源提供理论指导。     

风化壳淋积型稀土矿开采及分离技术的现状与发展

在查阅大量文献资料的基础上,阐述了风化壳淋积型稀土矿处理技术的现状,分析了目前风化壳淋积型稀土矿各种提取技术的主要特点;针对目前提取工艺中存在的一些问题,在原地溶浸的基础理论研究、新型沉淀剂的研发及除杂提纯技术等方面提出了下一步的发展方向.     

渗流作用下风化壳淋积型稀土矿细观孔隙结构演化特征

为研究风化壳淋积型稀土矿浸出过程中溶液渗流作用对孔隙结构的影响,以去离子水为溶浸液开展浸矿实验。对浸出前后矿样进行显微CT扫描,获取了试样内部结构图像,利用阈值分割算法得到了浸出前后稀土矿样的孔隙结构图像。进而,研究了溶液渗流作用下试样孔隙结构的变化特征,分析了渗流作用对试样孔隙率、孔隙体积、孔隙长度、孔隙宽度和孔隙方位角等参数的影响。结果表明:稀土矿孔隙形状和尺寸在渗流作用下发生显著变化,且在粗细颗粒接触区最为明显;溶液渗流作用使得稀土矿孔隙率增大,孔隙总数量减少,孔隙总体积增大。渗流作用下矿样中小孔隙数量减少,大孔隙数量增多,各尺寸区间的孔隙数量变化率随孔隙尺寸的增大呈现先增大后减小的趋势。溶液渗流作用下孔隙长宽比分布更加集中,孔隙方位角在各角度区间的分布更加均匀,孔隙各向异性增强。