浸矿过程离子型稀土矿体渗透特性演化机制研究

发布时间：2018-06-26 20:22

本文选题：离子型稀土 + 稀土离子含量　；参考：《江西理工大学》2017年硕士论文

【摘要】：目前,离子型稀土矿山浸取稀土所用的原地浸矿法已相当成熟,其具有工艺简单、出矿快、成本低等优点,然而在长期实际运用中,浸注过程引发的环境、事故问题时有报道,如滑坡、水土流失等,严重影响了该方法的推广。浸矿液浸注过程,矿体内部结构受化学-渗流耦合持续作用,微观孔隙结构发生变化,致使矿体渗透性发生改变,影响浸矿效果,甚至诱发矿体滑坡。本文为了研究矿体浸矿过程微观结构变化与试样宏观渗透性之间的关系,利用浸矿过程渗透系数测定装置,完成了浸矿过程稀土矿渗透系数测定实验,研究了离子交换条件下试样渗透系数变化规律及形成机理,分析了初始渗透性对渗流规律的影响。获得以下主要结论:(1)浸矿液为纯水时(0-17h),稀土离子含量(REO)在6.5*10-4g/t波动,根据公式(3.1)分析,表明此阶段重塑土样内部不发生化学交换反应;浸矿液为硫酸铵时(7-17h),根据离子含量的变化可将化学反应过程分为三个阶段:初始反应阶段(7-9h)、强烈反应阶段(9-14h)、结束反应阶段(14-17h),整体呈现先强后弱的变化规律。(2)浸矿过程中,稀土矿体内部微观孔隙结构受控于溶液渗流和离子交换两个过程的耦合影响,其中溶液渗流诱发矿体内部孔隙增多,孔径增大,微观结构趋于松散;而离子交换引起颗粒移动重组,导致孔径变小,孔隙数量减少,微观结构趋于紧密。(3)浸矿过程的离子交换反应在矿体中随溶液渗流逐层向下进行,符合渗流理论的层流规律;浸矿过程的化学置换和溶液渗流双重作用下,浸矿液渗流对矿体微观结构具有破坏作用,而化学置换对微观结构具有一定的修复作用。(4)纯水浸矿过程颗粒运移,渗流场稳定前有效渗流孔径增大,试样渗透系数逐步增加,渗流场稳定后试样渗透系数保持不变;硫酸铵溶液浸矿,在初始反应阶段和强烈反应阶段试样渗透系数呈现下降趋势,随着化学反应强度减弱渗透系数开始增大。(5)纯水浸矿过程在稳定渗流场形成前各试样渗透系数呈现上升的变化趋势且增加的幅度基本相当;硫酸铵溶液浸矿过程渗透系数变化趋势呈现先下降-后上升,变化幅度随试样初始渗透性降低而逐步减弱。因此,建议初始渗透性较差的稀土矿体可采用“先水后硫酸铵溶液”顺序浸矿,可达到最优浸矿效果。
[Abstract]:At present, the in-situ leaching method used for leaching rare earths in ion rare earth mines is quite mature. It has the advantages of simple process, quick ore drawing and low cost. However, in long-term practical application, the environment caused by leaching process and accident problems have been reported. Such as landslide, soil erosion and so on, seriously affected the popularization of this method. In the process of leaching, the internal structure of ore body is continuously influenced by the coupling of chemical and percolation, and the microscopic pore structure changes, which results in the change of the permeability of ore body, which affects the leaching effect and even induces the landslide of ore body. In order to study the relationship between the microstructure change of ore body leaching process and the macroscopic permeability of the sample, the experiment of determining the permeability coefficient of rare earth ore during leaching process was carried out by using the apparatus for determining the permeability coefficient of the ore leaching process. The variation law and formation mechanism of the permeability coefficient of the sample under ion exchange conditions were studied and the influence of initial permeability on the seepage law was analyzed. The main conclusions are as follows: (1) when the leaching solution is pure water (0-17 h), the rare earth ion content (REO) fluctuates in 6.5*10-4g/t, according to the formula (3.1) analysis, it shows that there is no chemical exchange reaction in the remolded soil at this stage; When the leaching solution is ammonium sulfate (7-17 h), the chemical reaction process can be divided into three stages according to the change of ion content: initial reaction stage (7-9 h), strong reaction stage (9-14 h), end reaction stage (14-17 h). The micropore structure of rare earth ore body is controlled by the coupling effect of solution percolation and ion exchange, in which the pore size increases and the pore size increases, and the microstructure tends to be loose. However, ion exchange leads to particle movement and recombination, resulting in the decrease of pore size, the decrease of the number of pores and the close microstructure. (3) the ion exchange reaction in the leaching process is carried out layer by layer with the solution percolation, which accords with the laminar flow law of seepage theory. Under the dual action of chemical replacement and solution seepage in leaching process, leaching fluid seepage can destroy the microstructure of ore body, while chemical replacement can repair the microstructure to some extent. (4) the particle migration in pure water leaching process. Before the seepage field stabilizes, the effective percolation pore size increases, the sample permeability coefficient increases gradually, the sample permeability coefficient remains unchanged after the seepage field stabilization, the ammonium sulfate solution leaching ore, At the initial reaction stage and the strong reaction stage, the permeability coefficient of the sample decreased, As the chemical reaction intensity weakens the permeability coefficient begins to increase. (5) the permeability coefficient of each sample increases before the steady seepage field is formed and the increase range is basically the same; The change trend of permeability coefficient in ammonium sulfate solution leaching process is first decreasing and then increasing, and the change range decreases gradually with the decrease of the initial permeability of the sample. Therefore, it is suggested that the rare-earth ore bodies with poor initial permeability can be leached in the order of "first water and then ammonium sulfate solution", and the optimum leaching effect can be achieved.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD865

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