【作者】 王洪江；

【导师】 吴爱祥；

【作者基本信息】 中南大学 ， 安全技术及工程， 2006， 博士

【摘要】 随着我国经济持续快速发展，矿产资源供需矛盾日益严重，对国外的依存度越来越大，将威胁到国家的资源安全。同时，矿产资源严重短缺与固体废弃物中的有价元素闲置形成鲜明对比，进行排土场等“人工矿床”二次资源开发迫在眉睫。虽然堆浸法是处理低品位矿石、表外矿、废石等贫呆资源的理想方法，但由于排土场堆体厚大、地形复杂、含泥量高、颗粒平均粒径大、矿石品位低等原因，造成浸堆渗透性差、浸出率及浸出液浓度低、细菌活性小等问题，致使浸出周期长、生产成本高，影响了堆浸法在排土场的推广应用。因此，进行排土场强化浸出技术研究对于缓解我国矿产资源供需矛盾、保障国家资源安全具有重要意义。本论文以德兴铜矿排土场细菌浸出为工程实例，结合国家973重点基础研究发展规划项目《微生物浸出体系多因素强关联》(2004CB619205)、国家杰出青年科学基金项目《散体多相介质中多级渗流传质的动力学研究》(50325415)以及国家创新群体项目《硫化矿生物提取的基础研究》(50321402)，对铜矿排土场强化浸出机理及其新工艺进行研究。本论文通过现场调查、室内实验、理论分析等手段，针对铜矿排土场浸出存在的问题，分析其关键因素，以排土场渗流机理以及新的布液收液方式为突破口，兼顾浸堆内温度控制与气体输送，开展溶浸液流动过程中动量传递、热量传递和质量传递规律研究，最终将理论成果集成于排土场浸出新工艺中，该技术应用潜力十分巨大。论文完成的主要工作如下：(1)实验发现，非均质体水平渗流效果明显优于垂直渗流，堆中布液方式极大地改善了浸堆内溶浸液的均匀性。非均质体具有渗流各向异性，其各向异性系数范围为63～155，是均质体的10～100倍；非均质体堆中布液渗流系数大于堆顶布液，两者比值在1．42～3．02之间。这一结论为解决渗透性差问题指明了改进方向，强化浸出新工艺应采用堆中布液方式。(2)首次进行了综合性强化浸出原生矿柱浸实验，为排土场强化浸出提供了技术原型。综合强化浸出同时采用驯化菌种、供气、控温、大流量四项技术措施，柱内温度高于常规浸出平均值5．8℃，细菌浓度始终处于上升趋势，铜浸出率提高了40．5％，浸出速率明显高于供气、控温单一强化浸出措施，浸出动力学控速步骤由界面化学速率转变内扩散。同时，铜浸出率与温度、通气量、布液强度成正比，证明大流量浸出有利提高浸出率；在浸出过程中，散体渗流系数随时间而逐渐下降，化学堵塞的影响大于机械堵塞，铁的沉淀是影响浸出顺利进行的重要因素。(3)基于势函数及其叠加原理，揭示了排土场浸堆中不同渗流状态下的渗流规律，认为直线二点形钻孔布置方式的浸堆单位面积流量最大。提出了浸堆最优布孔网度的三原则，建立了网度参数与钻孔影响半径的关系，推导了不同流态下影响半径、单位面积渗流量公式，在同等条件下推荐采用梅花形布孔方式。借鉴粗粒土渗流的经验公式，阐述了排土场散体渗透性恶化的原因在于散体压实后形成一水平弱透水层，渗流状态属于过渡流，浸堆渗流破坏形式为管涌形式，并得出新工艺有利于提高浸堆边坡稳定性的结论。(4)借助于热力学原理研究细菌浸矿作用机理，阐明了铜矿浸出过程中直接作用占主导地位。当细菌直接作用时，浸矿反应均为放热反应，而间接作用时均为吸热反应；硫化矿与氧作用时自由能较低，在同等条件下，硫化矿优先与氧作用，但温度高对直接作用不利；硫化矿与氧作用时的电位范围比与硫酸铁低，氧作氧化剂要优于硫酸铁。(5)利用多孔介质流体强制对流理论，揭示了浸堆内热量传导规律，为控温强化浸出提供理论指导。根据热流量平衡原理，建立了浸堆内放热量与散热量的守恒公式，为浸堆内流体传热奠定基础。由焓变原理以及主要伴生矿物，推导浸出反应热流量公式，表明黄铁矿浸出和硫氧化产生的热流量远远高于黄铜矿的热量。在自然对流传热理论的基础上，分析了浸堆向大气的散热量，其结果显示其值所占比例较小，可忽略不计。由物质比热容估算矿石吸热量，其值与现场实测数据基本吻合。最后借鉴多颗粒群强制对流传热原理，得出浸堆溶浸液换热关联式，结合德兴铜矿数据，证明了溶浸液作为媒介进行传热是可行的，溶浸液调节的热量占总热量的59.6～67.4％，夏季控温难度大于冬季。(6)探讨了氧气传输途径，借助气体传质理论对氧气传质规律进行了有益的探索。溶浸液中的溶解氧仅能维持细菌自身繁殖，无法满足化学反应需氧量。依靠人工通风于浸堆内，形成大量气泡，空泡发生溃灭出现瞬间高压来促进氧的溶解与传递。黄铁矿是铜矿浸出过程中主要耗氧竞争对象，随着黄铁矿含量的增加，耗氧量急剧增长。通过工程实例估算，证明采用供气强化浸出是可行的，单位体积矿石耗气量仅为0.77m~3／m~3，在现有设备的基础上比较容易实现人工强制供氧。(7)在上述强化浸出机理研究的基础上，提出了排土场强化浸出新工艺。新工艺是地表布液与堆内布液相结合的联合工艺，在高度方向上地表布液方式覆盖范围只能占15％，堆内布液方式承担绝大部分金属回收的任务。而人工供氧、温度控制成为管注法浸出的有机组成，智能化连续培养细菌是强化浸出技术的关键。以德兴铜矿堆浸厂实际生产资料为基础，预测了新工艺的主要经济技术指标，结果表明，新工艺的生产成本虽然较高，但由于提高了浸出率，总利润比旧工艺提高了11％，总体经济效益较好。更多还原

【Abstract】 Along with economy developing continuously and fleetly, the conflict of supply and need of mineral resource is severity increasingly in China, and its depending degress on foreign country is more higher, which will threaten the safety of national resources. Meanwhile the serious shortage of mineal resource and the idling of valuable element in solid waste forming vivid contrast, it is extremely urgent to exploit redeposit resource—"Artificial Deposit", such as dump. Although heap leaching is an ideal method for processing poor resources, example as low grade ore, out-of-list ore, waste rock and tailings, its application and popularization are limited in dump, because the dump has some disadvantages, such as thicker heap, complex topography, higher clay content, bigger average particle of grain and lower grade as well, which cause poor permeability, low leaching rate and lixivium concentration, poor bacterial activity, and long leaching period and higher product cost. So, it has important significant to study the technologies for accelerating leaching in dump for relaxing the conflict of supply and need of mineral resouyrce and ensuring the safety of national resources.This thesis focuses on studying the accelerating leaching mechanism and new technology of copper mine dump, taking the dump leaching plant of Dexing Copper Mine as an engineering example. It is supported by three projects that are 973 Program-National Basic Research Program of China "The Multifactor Strong Relating in Leaching System" (No.2004CB619206), National Science Fund for Distinguished Young Scholars of China "The Study on Dynamics of Multilevel Seepage and Mass Transfer in Multiphase Granular Medium" (No.50321402), and National Fund for Creative Research Groups of China "The Basic Research of Bioleaching Sulphide Ore" (No.50321402).Aimed at the problems existed in copper mine dump, with site investigation, indoor experiments, theoretical analysis, the paper analyzed the key factors. Taking seepage mechanism and new spreading and collecting liquid mode of dump as breakthrough, and compromising temperature control and gas transportation, it carried out the studies about momentum transfer, heat transfer and mass transfer rule in solution flow, and integrated theoretical achievements into the new technology of dump leaching finally, which has great applying potential.The main works that the thesis finished are as follows:(1) It was discoveried that seepage effect of level seeping is superior to vertical one obviously in heterogeneous body, and the spraying inside dump improve largely uniformity of solution in dump. It has anisotropism in heterogeneous body, and its anistotropy factor is between 63 and 155, which is 10 to 100 times of homogeneous body. The seepage factor of spraying inside dump is bigger than that of spraying on surface of heterogeneous body, where the ratio of them is 1.42 to 3.02. The conclusuon designates way to solve poor permeability, and the new technology should adopt the mode of spraying inside dump.(2) It was first to experiment on column leaching of primary copper sulphide ore with all-around accelerating leaching measure, and offered technical prototype for accerlating leaching in dump. It adopted together with four measures in synthetical acclerating leaching, which is domesticated bacterial, air feeding, temperature controlling, mass flow. The temperature inside column is 5.8℃high than one of conventional leaching column, the bacterial concentration is upward trend all along, and Cu leaching efficiency rise 40.5%. The leaching rate of synthetical acclerating leaching is high than one of single accerlating measure, such as air feeding and temperature controlling, which the ratedetermining step transform internal diffusion from surface chemical rate with the study on copper leaching dynamics. In the meanwhile, the leaching efficiency of copper is in direct proportion to temperature, air-flow rate and spraying intensity, which prove the mode of mass flow leaching being favorable for heightening leaching efficiency. In the course of leaching, the granular seepage coefficient drops gradually with time, and the influence of chemical jam is greater than that of mechanical jam, which Fe precipitation is key factor to decide if the leaching is succeed or not.(3) Based on potential function and its superposition principle, It was opened out the seepage law under the different seepage states in dump, and indicated that the flux unit area of two-point mode is maximum. It brought forward the three principle for optimal hole network, and erected the relation of hole network parameter and radius influened, and deduced that the formulas of the radius influenced and solution flux of unit area in different flow states, and it has priority to adopt the mode of cube under the same conditions. Reference for empirical formula of coare grained soil seepage, it was expatiated that the cause of permeablility exasperated is a level aquiard forming after granular compacted, the seepage state belongs to tranition flow, the destructional form of seepage is piping, and educed the conclusion that the new technical is favourable to enhance slope stability in dump.(4) Recur to thermodynamic principle, it studied on mechanism of bacterial leaching, and was clarified that the direct action holds the leading status in copper leaching. The leaching reaction are exothermic if bacterial act directly, and that are endothermic if bacterial act indirectly. The free energy is lower if sulphide ore act with oxygen, and sulphide ore act prioritically with cxygen under the same condition, but higher temperture makes against bacterial direct action. The range of electic potential if sulphide ore act with oxygen is lower than that with ferric sulfate, and oxygen is excelled to ferric sulfate as oxidant.(5) Utilizing the forced convection principle of fluid in porous medium, it opened out the the heat conduct law in dump, which provided theretical guiding to temperature controlling for accelating leaching. Basis on heat flux equilibrium theory, it established the conservation formula of exotherm and heat dissipated, which settles base on fluid transfering heat in dump. By enthalpy principle and the main associated mineral, it derivated heat flow formula of leaching reaction, which indicates heat flux from pyrite leached and sulfur oxygened outclass one from chalpyrite. With natural-convection heat transfer, it analyaed the heat disspating from dump to atomsphere, which is less ratio of totall heat flux and ignore. It estimated ore heat absorption by matter specific heat theory, which fits with observational data in field basically. Use for multiparticle swarm forced converction heat transfer theory, it elicited the heat exchange correlative formular, combining with Dexing Copper Mine data, it was a witness to heat transfer is feasble by solution, which heat adjusted by solution accounts for 59.6%～67.4% of the total heat, and temperature controlling in summer is difficult than in winter.(6) It discussed the oxygen transmitting path, probed into profitably oxygen transmitting theory under gas transferring theory. The dissolve oxygen only maintains bacterial self breeding in solution, but can’t satisfy the oxygen demanded in chemical reaction. Depending on artifical ventilation into dump, forming a great deal of bubble, oxygen dissovlling and transferring is promoted by high press instant as bubble crumble and fall. The pyrite is the main mineral competing for oxygen in leaching copper ore, and oxygen consumption increases sharply with pyrite increasing. By engineer example estimating, it proved air feeding for accelating leaching is feasible, which air constumption unit volume ore is only 0.77 m~3/m~3, and articial forcing oxygen supply realize easily on basis of available facilities.(7) On the basis of the above accelerating leaching mechanism study, it put forward the new craft of dump leaching accelerated. The new technology is coordinating process of spraying on surface and inside dump, which the coverage area of spraying on surface accounts 15% in height and the mode of spraying inside dump undertakes the most part of metal recovered. Air supplying and temperature controlling articially become organic composition of pipe-pouting method, and continuous culture bacterial technology intelligentized is key to accedating leaching technique. Based on actual production data of dump leaching plant in Dexing Copper Mine, it forecasted the main econo-technical indicators of the new technics. Although the new technology needs higher production cost, its gross profit is improved by 11% than that of the old one because leaching rate is enhanced, so the overall economic benefits are better.更多还原