基于原位剪切实验的稀土矿矿体力学特性分析

为了分析风化壳淋积型稀土矿不同高程矿体的力学特性,选取江西省某矿山边坡处不同高程矿体的原状土为研究对象,通过原位剪切实验,揭示不同高程原状土的抗剪性能,并研究了含石量对粘聚力和内摩擦角的作用机理。实验结果表明,稀土矿矿体的剪应力-剪切位移表现出应力-应变软化特性;随着所取矿体高程的增加,剪切面上纵坐标的剪应力值随横坐标剪位移的发展而出现上升变化趋势,但剪应力峰值呈现下降的趋势;矿体的强度与土体含石量有关,稀土矿矿体粘聚力和内摩擦角随着含石量的增大,而呈现增大趋势,最佳土石比为48%。原位剪切实验的结果可以为稀土矿矿山的稳定性计算提供合理的设计参考。     

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.      

风化壳淋积型稀土矿浸出渗流和传质过程研究现状及展望

风化壳淋积型稀土矿富含中重稀土,主要分布在中国的南方七省,目前主要用硫酸铵作为浸取剂的化学浸出法回收稀土。浸取剂在矿体中的渗流、传质过程直接影响着稀土浸出效率,强化其渗流、传质过程可以提高稀土浸出的有效渗流速度,加快稀土离子交换速率,降低浸取剂用量,缩短生产周期,实现稀土绿色高效回收。本文分析了风化壳淋积型稀土矿渗流、传质过程的研究现状,总结了风化壳淋积型稀土矿渗流、传质过程的强化方法。结果表明,继续探索浸取液在风化壳淋积型稀土矿矿体中的有效渗流扩散规律和找寻促进稀土传质的高效传质规律,并以此为指导筛选浸取剂和助浸剂、改进注液方式、增加外力场将是强化风化壳淋积型稀土矿渗流、传质过程的主要研究方向。     

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.      

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.      

风化壳淋积型稀土矿浸取分形动力学研究

风化壳淋积型稀土矿粒径分布特征是影响浸取性能的主要因素之一。以五种重组江西风化壳淋积型稀土矿为研究对象,通过柱浸实验和分形理论相结合的研究手段,探究稀土矿的粒径分布特征与分形维数的关系,以及其对浸取动力学性能的影响规律。结果表明,随着分形维数增大,小粒径颗粒质量含量随之增大,而大粒径颗粒质量含量随之减少,尤其是小于0.150 mm和大于1.400 mm粒径颗粒质量占比变化幅度较大,其余粒径颗粒变化幅度较小。随着分形维数增加,浸出的稀土浓度峰值逐渐增大,浸矿中稀土浓度峰值出现的时间变晚,稀土浸取率达到平衡所需要的时间变长。基于分形理论,构建了风化壳淋积型稀土矿浸取分形动力学模型,并证实了新模型具有较高的准确性,能够较好的定量描述浸矿中不同分形维数的稀土矿样的浸取动力学特性。     

风化壳淋积型稀土矿原地浸出微观渗流机制

为了揭示风化壳淋积型稀土矿原地浸出微观渗流机制,通过扫描电镜实验和图像处理技术,定量分析浸矿后四种稀土矿样的上、中、下部的微观孔隙结构特征(孔隙尺度、孔隙分布、孔隙形状)的变化规律,探讨宏观渗透系数与其的关系。研究结果表明,矿石颗粒的孔隙率由大、超大孔隙比例和与总孔隙数共同决定,随矿样深度增加而减小;下部矿样的孔隙尺度均匀程度最高,而中部矿样的最低;随着矿样深度增加,孔隙分布越来越分散,平均孔隙形状系数逐渐增大,孔隙形状特征变得越来越复杂;浸矿中-0.075 mm粒径矿石颗粒迁移导致微观孔隙结构特征和有效颗粒粒径改变,这是影响稀土矿石渗透性能变化的主要因素。研究成果有望为实现高效回收中重稀土资源提供理论依据。     

风化壳淋积型稀土矿浸取技术发展现状

对风化壳淋积型稀土矿的浸取技术进行了综述。根据该矿的浸出机理,分析了三种传统浸出工艺的利弊,结合最新研究成果,总结出4种新型浸出方式并指出了浸出工艺的发展趋势。在沉淀稀土工艺方面,重点论述了碳酸氢铵沉淀工艺及镁/钙盐体系下风化壳淋积型稀土沉淀的最新成果,最后提出了风化壳淋积型稀土矿浸取工艺的发展方向。     

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.     

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。      

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.     

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。     

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.     

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%.     

Local concentration of middle and heavy rare earth elements in the col on the weathered crust elution-deposited rare earth ores

This present study focused on investigating the content and relative enrichment multiple of rare earth elements(REEs) in different terrain of weathered ore body, and the value of light rare earth elements/middle and heavy rare earth elements(LREEs/HREEs), in order to understand the mobilization and redistribution of HREEs, Furthermore, the abrasion pH was investigated as well, The results show that the average contents of HREEs in the knap, ridge and col are 37.26, 61.71, and 271.3 μg/g, respectively. The value of LREEs/HREEs is decreased from 16.78 to 7.914 between knap and col and the relative enrichment multiple of HREEs is as follows: C_(Col-HREEs) C_(Ridge-HREEs) 0. It is indicated the HREEs is concentrated in the col and the enrichment degree of HREEs is stronger than the ridge and the knap. Rare earth elements fractionation is exhibited in the different terrain of weathered ore body. Based on this study, the finding that HREEs concentrate in the lower terrain of weathered crust elution-deposited rare earth ores, such as in the col, would become a marker or indicator to search for middle and heavy rare earth enriched zone.     

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。     

Enhanced Leachability of a Lean Weathered Crust Elution-Deposited Rare-Earth Ore: Effects of Sesbania Gum Filter-Aid Reagent

The enhanced leachability of rare-earth ore from the lean weathered crust elution-deposited rare-earth ores with ammonium sulfate solution as lixiviant and sesbania gum as a filter-aid reagent was elucidated and optimized with chromatographic plate theory. The effects of the flow rate, the concentration of lixiviant, the sesbania gum filter-aid reagent, and the lixiviant consumption on the leaching process were examined with column elution. The results show that the sesbania gum has a positive effect on the leaching process; the relationship between the height equivalent to a theoretical plate (HETP) and the leaching flow rate can be described by the van Deemter equation. There is an optimum flow rate in the leaching process. The optimum concentration of the sesbania gum in lixiviant was discovered. Moreover, sesbania gum added in lixiviant also reduces lixiviant consumption and promotes the optimum leaching flow rate. It provides a new approach to leaching the lean weathered crust elution-deposited rare-earth ores with high efficiency and low reagent consumption. The approach also can reduce the NH₄ ⁺-N pollution.