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。     

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.     

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．     

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.     

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.      

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。     

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.     

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.      

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.      

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。     

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.      

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。      

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.     

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.      

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.     

生物表面活性剂对原矿中稀土淋洗效果的影响

为实现我国南方离子型稀土矿的无铵浸析,以生物表面活性剂-皂角苷为浸矿剂,通过淋洗实验探讨了皂角苷浓度、溶液pH、原矿粒径、固液比对稀土淋洗效果的影响,结果表明:在原矿粒径为0.25 mm,皂角苷浓度50 g/L、pH=5.5和固液比(g/mL, 下同)1:15条件下,振荡24 h后,皂角苷对稀土的淋洗效率可达76.78 %.而在柱淋洗实验中,累积淋洗效率为43.16 %,仅不到硫酸铵的1/2;原因在于皂角苷对稀土的淋洗效率会受溶液和原矿的性质、流速等因素的影响,导致淋洗反应迟缓,拖尾期长.      

Solution-chemistry analysis of ammonium bicarbonate consumption in rare-earth-element precipitation

A solution-chemistry analysis is applied to estimating the consumption of ammonium bicarbonate in the recovery of rare-earth (RE) elements from leachates of weathered clays. The theoretical analysis shows that a two-step process is needed for recovering RE from the leachates of the weathered clays by precipitation using ammonium bicarbonate. The first step is a precipitation at solution pH 5 to remove impurities such as Fe and Al. The second step is to precipitate RE by adjusting the solution pH above 8. The consumption of ammonium bicarbonate was found to depend on the concentration of RE elements and impurities in the leachates. The total amount of ammonium bicarbonate consumption for the entire process was determined experimentally, and the results showed an excellent agreement with that calculated based on solution-chemistry analysis. The decomposition of H₂CO₃ was identified as one of the main causes of ammonium bicarbonate overdose, accounting for up to 41 pct in comparison to 20 pct consumption for the removal of impurities. The amount of ammonium bicarbonate required in terms of the NH₄HCO₃: RE₂O₃ (RE oxides) molar ratio was found to be 4:1 for maximal RE recovery. An overall RE recovery around 90 pct was achieved with a product purity being about 90 pct.