【作者】 黄颖；

【导师】 罗嗣海；

【作者基本信息】 江西理工大学 ， 矿业工程， 2025， 博士

【摘要】 离子型稀土矿地质条件复杂,采用原地浸矿工艺开采时,仅依赖于工程经验确定浸矿剂用量和注液孔间距,容易出现浸矿剂过量、浸矿剂不足和注液盲区等问题。离子型稀土浸矿包含了离子交换和离子迁移两个过程,基于溶质运移理论,构建稀土浸出过程的离子交换模型和数值模拟方法,是因地制宜设计注液方案,高效提取稀土资源的有效手段。然而,目前缺乏适用于离子型稀土浸矿的离子交换模型和高精度、高效率的模拟方法。为了解决该问题,本文主要的研究内容和研究结论如下:(1)研究了铝离子、钙离子和钾离子杂质与稀土离子的竞争交换特性,并建立了多离子竞争交换模型。结果表明,浸矿剂溶液的氢离子浓度会影响交换前固相稀土离子和铝离子的浓度;当浸矿剂溶液中硫酸根离子浓度小于0.20 mol/L时,浸出的钙离子与硫酸根离子基本不会形成硫酸钙沉淀,即在本文的实验条件下,硫酸镁交换钙离子的过程与钾离子类似,均为可逆的离子交换反应。采用建立的多离子竞争交换模型分析实验数据,模型计算值与试验值的决定系数基本在0.800以上,验证了模型的合理性。(2)以建立的多离子竞争交换模型为源汇项,结合对流-弥散方程,构建了一维浸矿过程的基本方程。针对解对流占优溶质运移方程容易出现振荡和弥散的问题,引入加权基本无振荡格式,提出一维离子型稀土浸矿过程的高精度模拟方法。对比分析数值模拟结果与室内柱浸试验数据,穿透曲线的决定系数均在0.930以上,浸矿后稀土离子残留分布的决定系数均大于0.900,验证了模拟方法的合理性。与上游加权法进行对比,提出的方法能完全解决对流占优溶质运移方程解的振荡问题。对于稳定流,误差小于2.00%。同时,该方法容易推广至非饱和流,兼顾了精度高与易推广的优点。(3)采用时间算子分裂思想将离子型稀土三维浸矿过程的基本方程解耦为多个一维方程,构建三维浸矿过程的解耦模拟方法。通过该方法分析矿体土壤类型和初始含水率对水流和离子运移的影响规律,结果发现,水流运动的湿润体呈现椭球状,其水平和垂直入渗距离随时间的变化规律可以采用Kostiakov模型量化,湿润体的中心坐标随时间的变化可采用多项式描述。在此基础上,构建了湿润体前锋面的数学模型,其决定系数大于0.980,具有较高的精度。浸矿区域同样呈椭球状,但滞后于水流运动区域。随着矿体渗透性的增加,水平方向上浸矿区域越小,适当增加矿体的含水率可以增加水平浸矿距离,浸矿区域水平方向的最大距离可以为注液孔间距的设计提供依据。更多还原

【Abstract】 Ion-adsorption type rare earth ores(IATREOs)are characterized by complex geological conditions.During in-situ leaching of IATREOs,the dosage of leaching agents and the separation between injection holes are designed only by engineering experience,leading to problems such as excessive leaching agents,insufficient leaching agents,and blind areas of injection.The leaching technology of(IATREOs)involves two fundamental processes:ion exchange and solute migration.Based on the solute transport theory,a numerical simulation method was constructed for the leaching process of IATREOs,which could provide a valid approach for designing liquid injection schemes according to local conditions and achieving efficient extraction of ion-adsorption type rare earth resources.However,there was currently a lack of ion exchange models and high-precision,high-efficiency simulation methods suitable for the leaching process of IATREOs.To address these issues,the main research and conclusions of this article are as follows:(1)The competitive exchange characteristics of impurities,including aluminum,calcium,and potassium ions,with rare earth ions were investigated,and a multi-ion competitive exchange model was subsequently developed.The results indicated that the hydrogen ion concentration in leaching agents significantly affected the concentrations of solid-phase rare earth ions and aluminum ions before the exchange process.When the sulfate ion concentration in leaching agents was less than 0.20 mol/L,the leached calcium ions and sulfate ions hardly formed calcium sulfate precipitation.Thus,under the experimental conditions of this study,the process of magnesium sulfate exchanging calcium ions was similar to that of potassium ions,both being reversible ion exchange reactions.Analyzing the experimental data with the established multi-ion competitive exchange model,the determination coefficients between the calculated values and the experimental values were generally above 0.800,validating the rationality and reliability of the model.(2)Taking the established multi-ion competitive exchange model as the source-sink term and integrating it with the convection dispersion equation,a fundamental equation for the one-dimensional leaching process was constructed.To resolve the oscillation and dispersion problems encountered when solving the convection-dominated solute transport equation,a weighted essentially non-oscillatory(WENO)scheme was introduced to propose a high-precision simulation method for the one-dimensional leaching process of IATREOs.Comparing the numerical simulation results with the indoor column leaching test data,the determination coefficients of the breakthrough curves were all above 0.930,and those of the residual distribution of rare earth ions after leaching were all greater than 0.900.The results verified the rationality of the simulation method.In contrast to the upstream weighting method,the proposed method can completely solve the oscillation problem of convection-dominated solute transport equation.For stable flow,the error was less than 2.00%.Meanwhile,the proposed method could be readily extended to unsaturated flows,possessing the advantages of high accuracy and ease of generalization.(3)By applying the time operator splitting concept,the governing equations for the three-dimensional leaching process of IATREOs were decoupled into a system of one-dimensional equations,thereby a decoupling simulation method for the three-dimensional leaching process was constructed.The simulation method was employed to analyze the influence of soil type and initial moisture content on water flow and ion transport in the ore body.It was found that the wetted body of water flow movement exhibited an ellipsoidal shape,and the variation of horizontal and vertical infiltration distances with time could be quantified by the Kostiakov model.Additionally,the center coordinates of the wetted body over time were described by polynomial functions.Based on these results,a mathematical model for the wetted body front was constructed,with a determination coefficient greater than 0.980,indicating high accuracy.The leaching zone similarly displayed ellipsoidal but lagged behind the water flow movement.As the permeability coefficient of the ore body increased,the horizontal direction of the leaching zone became smaller.With the water content of the ore body increasing appropriately,the horizontal direction of the leaching zone increased.The maximum horizontal distance of the leaching area could serve as a reference for designing the separation between injection holes.更多还原