Rule of oxygen transmission in dump leaching

1 INTRODUCTIONBioleaching the complex,low grade minerals ,submarginal ore and tailings has the advantages ofshort process and low cost , which can make fulluse of resources and i mprove environment . Butbioleaching also has some li mitation such as slowspeed and low rate of leaching due to slow breedvelocity andlowactivity resultingfrombad growthcondition[1 3]. However oxygen under supplying isalso the restriction of leaching reaction.In cyaniding,oxygen supplyis veryi mportantfor leachin…     

Experimental Study of Preferential Solute Transportation During Dump Leaching

1 Introduction Low-grade mineral resources can effectively be recovered by dump leaching techniques. It is useful to extract metals from secondary sources such as dump- ing and waste disposal sites, tailing piles and so on. At present, dump leaching has widely been applied in mining of copper, gold, silver and uranium, because of its many virtues, such as simple and environment friendly techniques, lower investment and higher utilization rates[1–5]. Considerable economic and so- cial benefits…     

铀矿石微生物堆浸技术浅议

铀矿石微生物堆浸是将细菌冶金技术与铀矿石堆浸工艺相融合的一项工艺技术,本文介绍了铀矿石微生物堆浸的发展、原理及影响堆浸效率的因素。     

基于自然电位的充填裂隙溶质运移特征试验研究

为精细描述充填裂隙溶质运移过程及其特征,设计加工了充填裂隙溶质运移试验模型,开展了不同流速条件下溶质运移试验,研究了充填裂隙溶质运移特征,结合不同测点自然电位(SP)实时动态监测数据,详细刻画了充填裂隙内部溶质运移过程。结果表明,在试验流速范围内,水流符合达西定律；随着流速增加,取样口处溶质峰值浓度增加,初始到达和峰值到达时间均减少。不同流速条件下,溶质运移过程中自然电位响应呈现出相似特征,均反映出溶质弥散前锋与溶质弥散峰值浓度区随水流动均呈匀速运移状态。利用峰值自然电位数据计算的水流宏观平均流速与采用溶质峰值浓度计算结果基本一致,但峰值自然电位计算流速值更接近根据流量计算平均流速,且流速越大,二者误差越小；同一流速条件下,随着溶质运移距离增加,自然电位峰值呈对数规律增加。     

高磷赤铁矿两步法生物除磷实验研究

采用嗜酸氧化硫硫杆菌(At.t)直接浸出和两步法浸出,对鄂西高磷鲕状赤铁矿(铁品位43.50%,磷含量0.85%)进行生物除磷的实验研究。结果表明:矿浆浓度为2%时,At.t菌直接浸出除磷率为62.35%,且硫含量高达28.57%;采用两步法摇床培养At.t菌,24d菌液pH值接近0.8,磷含量可降至0.15%,硫含量为1.09%;采用自行设计制作的生物反应器培养At.t菌8d,菌液pH值接近0.98,分离菌液浸出原矿12h磷含量为0.18%。对磁选精矿进行的两步法浸出表明,当矿浆浓度为3%以下时菌液的除磷效果明显。     

Enhancing the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect with sodium dodecyl sulfate surfactant

Ameliorating the problem of low leaching efficiency, long leaching period, and high agent consumption should be studied to efficiently exploit ion-absorbed rare earth ore resources. In this study, the surfactant sodium dodecyl sulfate (SDS) is used to enhance the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect for the first time. The effects of surfactant concentration, leaching agent dosage, solution flow velocity, and solution pH on the leaching rate were explored, and the mechanism of SDS was discussed. Under the optimum conditions, the addition of a small amount of SDS (mass fraction 0.04%) can increase the leaching rate by about 5%, shorten the leaching period, and reduce the consumption of the leaching agent. SDS significantly ameliorates the seepage effect of the ore body by reducing the surface tension of the leaching agent and ameliorating the wettability of the mineral surface. This effect is the main factor that improves the leaching efficiency. DFT (density functional theory) calculation results show that SDS can react with rare earth ions, which reduces the adsorption strength on clay mineral surfaces. Hence, rare earth ions are easily exchanged by ammonium ions, and mass transfer is enhanced.     

Simulation of solute transportation within porous particles during the bioleaching process

A mathematical model,accounting for the sulfuric acid and ferric ions diffusion and the copper sulfide mineral leaching process, was developed for an ore particle by considering its porous structure.It was simulated with the simulation tool COMSOL Multiphysics.The simulation results show that the highest acid and ferric concentrations near the particle surface are apparent,while the concentrations in the central particle increase slightly as the less-porous ore core with low permeability prevents the oxi...     

Heat transfer law in leaching dump

1INTRODUCTION Themethodofmicroorganismleachingcom plicatedmineraliseconomical,effective,andgoodforenvironmenttotreatlowgrademetalsulphideore[1].Since1980s,Dexingcopperminehasbegun toperformexperimentsonbacterialeachingcopperwastedump,whichisatypicalexampleoftheearth ssurfacedumpleaching.Butinthelong termofresearch,thedensityandactivationofthebacteriaarelower,whichisthemainfactorofhin deringthistechnologyfromadvancing[24],andleadstothesituationwithpooroperationeffectanddifficultytomaintain…     

基于通风强化浸出的矿岩散体孔裂隙双重介质结构演化

为解决羊拉铜矿非生物堆浸中铜浸出效果不佳的问题,提出了通风强化浸出的设想,以期从改善浸堆体系渗透特性方面来提高浸出效果。首先,针对现有堆浸多孔介质渗流理论在分析复杂渗流规律中的不足,提出利用堆浸散体的孔裂隙双重介质理论来研究强制通风的影响机制;然后,对该矿浸堆的矿石粒级分布情况进行了分析;最后,开展了不同通风强度下的室内柱浸实验,利用CT扫描技术分析了不同试件孔隙的发育情况,并利用电镜扫描(SEM)与分形几何理论对不同通风强度下散体颗粒表面的分形维数、动态裂隙率及动态渗透系数进行了研究。结果表明：羊拉铜矿浸堆的松散细颗粒较多,矿堆密实度较高,矿石颗粒粒级分布不合理;引入强制通风可以促进堆浸体系的孔裂隙结构发展并会对堵塞的渗流通道形成有效冲破,从而提高浸出反应程度并强化浸出液中溶质的渗流性能,最终提高矿石浸出效果。     

于家沟地下水反应溶质运移规律数值仿真

针对矸石淋滤液对于家沟地区地下水污染的实际情况,分析其在含水层中运移的规律,充分考虑了地 下水变密度对浓度分布的影响,建立了多组分溶质在地下水中运移的耦合动力学数学模型,采用Galerkin有限 元方法和Picard迭代法相结合对耦合模型进行了离散,通过室内土柱实验求得基本参数并对地下水污染的动态 过程进行了仿真模拟,预测了污染浓度的时空分布特征。结果表明:污染面积随时间推移不断向两轴方向扩 大,且纵向显著;不同组分由于各自特征的巨大差异,受到地下水密度影响的程度也有很大差别;渗滤液浓度拟 合误差小于6%,从而验证了模型的可靠性和实用性。     

土体固结与溶质运移三维耦合模型

考虑堆场上覆堆积体自重引起的土体固结与溶质运移的耦合效应已成为环境土工领域中的热点问题。在 Biot 固结理论和溶质运移理论相结合的基础上,以孔隙率作为耦合参量,将固结方程与运移方程相联系,考虑土体固结对溶质运移模型参数的影响,建立了溶质在固结变形土体中运移的三维耦合模型。采用多场耦合有限元软件 COMSOL Multiphysics 对模型进行了数值求解。数值模拟结果表明,土体固结变形对溶质运移过程具有较强和持久的阻滞作用,导致溶质运移深度以及污染羽范围的减小,在模拟运移20 a 时,运移距离减小率已高达27．75％,且随着时间的增加而逐渐增大;溶质在水平方向的迁移距离不可忽略,随着横向水力梯度的增大而增大。     

Insight into the structural evolution of porous and fractured media by forced aeration during heap leaching

Despite lots of techniques in improving the heap leaching performance, many constraints on the industrial applications remain. We proposed a correspondingly effective and new idea of introducing forced aeration to improve the bad permeability and leaching effect of Yangla Copper Mine (YCM) during heap leaching. The dual-media theory was employed to study the impact mechanism of forced aeration on the variations of porous and fractured media during the column leaching experiments. An X-Ray Computed Tomography (CT) set was utilized to perform the pore imaging of the specimens and the fracture morphology of the particles within the columns was analyzed by Scanning Electron Microscope (SEM) as aeration rate (AR) changed. The results show that there exists copious fine particles within the heap of YCM, the particle size distribution of which is not reasonable. The forced aeration can not only promote the development of the porous and fractured structures but effectively break the blocked seepage paths. Then the leaching degree is improved and the seepage performance of the solute within the solution is enhanced. Therefore, the forced aeration is probable of making the leaching performance greatly improved.     

Dynamic experiment and numerical simulation of solute transmission in heap leaching processing

Solute transmission in saturated ore heap was studied numerically and experimentally. The convection-diffusion equation (CDE) used to describe the mass transportation in porous media was solved by characteristic difference method to give the distribution of the concentration of ferrous ion in the ore column. To calibrate the computational model, a column test was performed using infiltration of sulfide ferrous solution (the initial concentration is c0=0.04 mol/L) on a 100 cm high column composed of ore particles smaller than 10 mm for 2.5 h. The numerical analysis shows that the results obtained from numerical modeling under the same operating conditions as used for column test are in good agreement with those from experimental procedure on the whole trend, which indicates that the model, the numerical method, and the parameters chosen can reflect the rule of ferrous ion transmission in ore heap.     

西北某铀矿山铀矿石浸出性能室内试验研究

为了获得西北某铀矿山工业堆浸试验所需试验参数,对该铀矿矿石进行了搅拌浸出条件试验和-5 mm、-10 mm两种不同粒级的柱浸试验.试验结果表明：1）该铀矿石浸出性能较好,酸耗较低,适宜采用酸法浸出;2）氧化剂对酸法浸出的作用不明显,而对碱法浸出有一定的效果;3）铀矿石粒度对铀的浸出影响显著.     

APPLICATION OF MICROBIAL OXIDATION OF PYRITE

Thiobacillus ferrooxidans can be self-cultured in the acidic mine water after nourishing treatment.The mine water containing Thiobacillus ferrooxidans has been used in the heap leaching of pyritic-coal-bearing kaolin ore.The kaolin ore has been purified through the oxidation leaching of pyrite to remove the sulfur and iron impurities.     

Bioleaching of marmatite using moderately thermophilic bacteria

The process of bioleaching marmatite using moderately thermophilic bacteria was studied by comparing marmatite leaching performance of mesophiles and moderate thermophiles and valuating the effect of venting capacity as well as pulp density on marmatite leaching performance of moderate thermophiles. The results show that moderate thermophiles have more advantages over mesophilies in bioleaching marmatite at 45℃ and the pulp density of 50 g/L, and the zinc extraction efficiency reaches 93.1% in 20 d. Aeration agitation can improve the transfer of O2 and CO2 in solution and promote the growth of bacteria and therefore, enhance the leaching efficiency. Under the venting levels of 50, 200 and 800 mL/min, the zinc extraction efficiencies by moderate thermophiles are 57.8%, 92.5% and 96.0%, respectively. With the increase of pulp density, the total leaching amount of valuable metals increases, however, the extraction efficiency decreases due to many reasons, such as increasing shear force leading to poorly growth condition for bacteria, etc. The zinc extraction decreases remarkably to 58.9% while the pulp density mounts up 20%.     

铀矿堆浸中粒度对浸出率的影响

介绍７７１矿进行铀矿地表堆浸试验．在该矿原有小型试验基础上，本次试验进一步得出结论：粒度越小，浸出率越高．     

对流下二元合金凝固过程的相场法研究

采用耦合流场的相场模型,以Ni-Cu二元合金为例模拟金属非等温凝固和等温凝固时的枝晶生长,把两种模拟结果作比较。发现：两种模型得出的结果都与溶质再分配理论相符合;潜热的释放在一定程度上抑制枝晶的生长,使得非等温凝固时的平衡再分配浓度比等温凝固时低;非等温凝固的生长Peclet数与Oseen-Ivantsov理论值吻合得更好。     

Technological conditions and kinetics of leaching copper from complex copper oxide ore

The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H₂SO₄ concentration, particle size of crude ore and agitation rate on the leaching efficiency of copper were also evaluated. And the kinetic equations of the leaching process were obtained. The results show that the leaching process can be described with a reaction model of shrinking core. The reaction can be divided into three stages. The first stage is the dissolution of free copper oxide and copper oxide wrapped by hematite-limonite ore. At this stage, the leaching efficiency is very fast (leaching efficiency is larger than 60%). The second stage is the leaching of diffluent copper oxides, whose apparent activation energy is 43.26 kJ/mol. During this process, the chemical reaction is the control step, and the reaction order of H₂SO₄ is 0.433 84. The third stage is the leaching of copper oxide wrapped by hematite-limonite and silicate ore with apparent activation energy of 16.08 kJ/mol, which belongs to the mixed control.     

PCR-DGGE技术分析浸矿体系细菌群落结构的实验优化

为了研究低品位黄铜矿细菌搅拌浸出的浸矿菌液中的细菌群落结构,对 PCR-DGGE(变性梯度凝胶电泳)技术相关的实验方法进行了优化,主要涉及低丰度基因组 DNA提取方法优化、16SrRNA基因的 PCR扩增条件优化以及变性梯度凝胶电泳条件的优化.结果表明,采用分级离心多次浓缩的方法收集矿浆样品中的菌体,再用试剂盒提取基因组 DNA,有较好效果;使用含特定“GC夹板”的引物5′-CGCCCGCCGCGCCCCGCGCCCGTCCCGCCGCCCCCGCCCG-3′进行热启动降落 PCR,能显著提高目的条带的 PCR扩增效率;当 DGGE电泳设置温度为60℃左右,胶浓度为6%,尿素变性梯度为30%~50%,恒定电压为100V,时间为9h时,可以获得效果较好的 DGGE电泳图谱,该优化方案提高了对浸矿体系中细菌群落结构的检测效果