Simulation of coupled flowing-reaction-deformation with mass transfer in heap leaching processes

Governing equations for a fully coupled flowing-reaction-deformation behavior with mass transfer in heap leaching are developed. The model equations are solved using an explicit finite difference method under the conditions of invariable application rate and constant hydraulic head. The distribution of the degree of the saturation, as well as the distributions of the concentration of the reagent and the solute is given. A cubic relationship between the mineral recovery and the leaching duration is obtained based on the numerical results. The relationship can be used to predict the recovery percentage of the valuable metal.

Analysis of coupled flow-reaction with heat transfer in heap bioleaching processes

A mathematical model for heap bioleaching is developed to analyze heat transfer, oxygen flow, target ion distribution and oxidation leaching rate in the heap. The model equations are solved with Comsol Multiphysics software. Numerical simulation results show the following facts： Concentration of oxygen is relatively high along the boundary of the slope, and low in the center part where leaching rate is slow. Temper- ature is relatively low along the slope and reaches the highest along the bottom region near the slope, with difference being more than 6℃. Concentration of target mental ions is the highest in the bottom region near the slope. Oxidation leaching rate is relatively large in the bottom and slope part with a fast reaction rate, and small in the other part with low oxygen concentration.

Pretreatment of copper-bearing refractory gold ores by bio-heap leaching

The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique （all-sliming cyanidation）, the gold recovery rate is only 51.78%. To eliminate the negative effects of copper and pyrite on cyanidation and increase the gold recovery rate, the investigation on bio-heap leaching pretreatment was made, by which Cu would be dissolved and gold would be liberated from pyrite. The experiment adopted mixed bacteria, mainly ThiobaciUus ferrooxidan （named T.fl ）, as the bacterial catalyst for bio-preconditioning and was carried out in a PVC column with a diameter of 20 cm and a height of 1.3 m loaded with gold ores. The temperature was controlled between 28 and 30℃, the pH value was kept between 2.0-2.5, and the flux of sprinkling bacterial liquid was maintained 0.80 L/h. After 45-day＇s bio-oxidization, among the samples sizing from 0 to 5 mm, the oxidation rates of Cu, Fe and S were respectively 44.62%, 28.16% and 25.46%, and the gold recovery rate by cyaniding increased to 80.35%. The bio-heap leaching pretreatment can therefore effectively dissolve Cu and liberate gold from pyrite and lead to the increase of gold extraction.

Mathematical model for coupled reactive flow and solute transport during heap bioleaching of copper sulfide

Based on the momentum and mass conservation equations,a comprehensive model of heap bioleaching process is developed to investigate the interaction between chemical reactions,solution flow,gas flow,and solute transport within the leaching system.The governing equations are solved numerically using the COMSOL Multiphysics software for the coupled reactive flow and solute transport at micro-scale,meso-scale and macro-scale levels.At or near the surface of ore particle,the acid concentration is relatively higher than that in the central area,while the concentration gradient decreases after 72 d of leaching.The flow simulation between ore particles by combining X-ray CT technology shows that the highest velocity in narrow pore reaches 0.375 m/s.The air velocity within the dump shows that the velocity near the top and side surface is relatively high,which leads to the high oxygen concentration in that area.The coupled heat transfer and liquid flow process shows that the solution can act as an effective remover from the heap,dropping the highest temperature from 60 to 38 °C.The reagent transfer coupled with solution flow is also analyzed.The results obtained allow us to obtain a better understanding of the fundamental physical phenomenon of the bioleaching process.

Evolvement of permeability of ore granular media during heap leaching based on image analysis

The column leaching experiment of ore granular media was carried out with the home-made multi-functional experimental apparatus and the pore structure of ore granular media was scanned by the X-ray computed tomography machine before and after leaching.The porosities of each section before and after leaching were calculated based on CT images processing,and the permeability of each zone before and after leaching were also calculated with Carman-Kozeny equation.The permeability evolvement law was disclosed.The results indicate that before leaching the permeability of the ore granular media in different height has not much difference and the value ranges from 5.70×10-4mm 2to 1.11×10 -3mm 2,where the lowest one locates in the bottom zone.After leaching the permeability distributes inhomogeneously along the height of the column and the value ranges from 3.44×10 -4 mm 2 to 2.25×10 -2 mm 2 ,where the lowest one is in the same place.Except for the bottom zone,the permeability of other zones increases after leaching,especially the top zone.Through comparison of the permeability at bottom zone before and after leaching,the whole permeability after leaching decreases by 39.65%that coincides with the measured experimental data.

Simulation of pore scale fluid flow of granular ore media in heap leaching based on realistic model

Two-dimensional images of the granular ore media with different grain sizes were obtained from the X-ray computed tomography.Combined with the digital image processing and finite element techniques,the original grayscale images were transformed into the finite element models directly.By using these models,the simulations of pore scale fluid flow among particles were conducted with the COMSOL Multiphysics,and the distribution characteristics of fluid flow velocity and pressure were analyzed.The simulation results show that there exist obvious preferential flow and leaching blind zone in each granular medium.The flow velocity at pore throat is larger than that of pore body and the largest velocity reaches 0.22 m/s.The velocity decreases gradually from the center of pore throat and body to the surface of particles.The flow paths of granular media with larger grain size distribute equally,while the fluid flow velocities in most of areas of granular media with smaller grain size are lower,and some of them approach to zero,so the permeability is very low.There exist some pore clusters with different pressures,which is the basic reason for the uneven flow velocity distribution.

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.

Research progress in enhanced bioleaching of copper sulfides under the intervention of microbial communities

Compared with the traditional pyrometallurgical process, copper bioleaching has distinctive advantages of high efficiency and lower cost, enabling efficiently extracts of valuable metal resources from copper sulfides. Moreover, during long-term industrial applications of bioleaching, many regulatory enhancements and technological methods are used to accelerate the interfacial reactions. With advances in microbial genetic and sequencing technologies, bacterial communities and their mechanisms in bioleaching systems have been revealed gradually. The bacterial proliferation and dissolution of sulfide ores by a bacterial community depends on the pH, temperature, oxygen, reaction product regulation, additives, and passivation substances, among other factors. The internal relationship among the influencing factors and the succession of microorganism diversity are discussed and reviewed in this paper. This paper is intended to provide a good reference for studies related to enhanced bioleaching.

Lime Assisted Cyanide Leaching of Refractory Gold Ores from Ajialongwa Mine

Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the effectiveness of lime for enhancing gold leaching rates of gold ores from ajialongwa gold mine in china. Column and heaping experiments were performed using cyanide leaching solutions at pH=10, with and without lime (CaO). The presence of lime greatly increased gold leaching rates. Column leaching experiments showed without the addition of lime, there was 35.2% of gold leached. The addition of lime resulted in the release of 50.56% gold. Lime assisted cyanide of refractory gold was proved by heap leaching experiments.

基于形态学开运算的浸矿体系孔隙结构及其演化特征

立足堆浸体系的偏析分层复杂结构,结合X-ray CT无损探测、形态学开运算处理、MATLAB和OsiriX可视化软件等手段,引入颗粒间孔隙的当量孔隙尺寸、面积、数量等关键表征参量,如从二维量化和三维可视化层面揭示浸矿体系中颗粒间孔隙结构特征及其演化规律.研究发现,细颗粒夹层呈“包裹体”状且均位于粗矿石颗粒的内部,分析认为其是造成堆浸体系颗粒偏析和分层的重要致因;浸矿作用下微细颗粒迁移导致矿堆内部发生沉积压实作用,由197 mm降至180 mm以下;浸矿21 d后,矿堆上部孔隙呈增大趋势,下部孔隙率呈减小趋势,此外,纵向当量孔隙的直径由2.81 mm减小至2.18 mm,其变化趋势和程度要显著大于横向颗粒间孔隙的当量直径;对比浸矿0 d和21 d的柱浸体系三维颗粒间孔隙结构,证实了细颗粒夹层所处区域的粘结聚集以及细颗粒夹层周边区域形成溶液绕流、溶液优势流动路径.

高含泥氧化铜矿水洗-分级堆浸工艺

通过室内实验分析高泥矿堆渗透性影响因素,探明入堆颗粒粒径、颗粒结构、泥质对浸堆渗透性的影响规律。结果表明:-1 mm的粒级的物料对浸堆渗透性具有恶化作用,去除后浸堆的渗透系数可增加19~47倍;入堆颗粒粒径与矿堆渗透系数呈二阶指数函数关系,当粒径小于10 mm时,渗透系数随粒径增大而缓慢增加;当粒径大于10 mm时,渗透系数随着粒径的增大而迅速增加。最后,提出采用水洗-分级工艺将-1 mm粒级物料进行槽浸和搅拌浸出,将+1^-5 mm和+5^-25 mm的物料进行分级筑堆、分区喷淋的堆浸方式。采用此工艺后,浸堆的渗透系数增加为原矿的8~50倍,综合浸出率由不到10%提高到63.98%,使高含泥氧化铜矿得到成功堆浸。

堆浸工艺中流动-反应-变形-传质耦合过程数值模拟及应用

基于堆浸过程中的孔隙变形,发展了一孔隙发育模型,并建立了堆浸工艺中流动-反应-变形-传质全耦合模型控制方程组,在喷淋强度不变和常水头的的情况下,给出了方程的数值解.数值结果描述了浸出过程矿堆中溶浸液饱和度的分布、溶浸剂浓度和浸出矿石浓度的分布,拟合结果表明:有用矿物浸出百分比与浸出时间之间呈3次关系,这一关系可用来预测堆浸中的有用金属的浸出回收率.

堆浸体系内微细颗粒在孔隙内迁移和附着规律

在堆浸过程中,堆浸体系内游离的颗粒会随着溶液的流动而移动,从而对浸出的速度和效率产生影响.对于粒径较小的微细颗粒,虽然难以对矿石颗粒间孔隙产生堵塞,但其在孔隙壁表面的大量附着也会影响溶液对矿石的内渗从而降低浸出效率.本文基于真实的孔隙结构使用Fluent软件开展仿真模拟实验,从粒径、颗粒密度和流体流速三个方面探究它们对微细颗粒在孔隙内迁移和附着行为的影响.模拟结果表明,当颗粒粒径为1×10^(-6) m时几乎没有颗粒会沉积附着在孔隙内.而随着粒径的增大,在1×10^(-6)~1×10^(-4) m的粒径范围内,附着在孔隙壁表面的颗粒数量会呈现先增多后减少的趋势,且对于不同密度的颗粒,其附着数量在峰值处的占比均超过了90%.观察发现颗粒的主要附着部位为弯孔隙的外壁以及流速较小、坡度较缓的小孔隙内.分析认为粒径和密度越大的颗粒,其重力和惯性对其运动轨迹的影响越大,而流体对其轨迹运动的影响越小,在迁移过程中更容易靠近孔隙壁从而导致颗粒附着.且大粒径、大密度的颗粒主要在大孔隙内迁移,轨迹较为集中.而小粒径、低密度的颗粒,在高流速流体内迁移时,其水平运动幅度更大,迁移轨迹分布更加分散,更容易进入小孔隙内迁移.

细菌堆浸中流动-反应-传热耦合过程数值模拟分析

针对辉铜矿微生物浸出过程进行数学建模,利用Comsol Multiphysics软件对浸堆中热量传递、氧气流动、目的金属离子分布以及氧化转化率等进行数值模拟分析.结果表明:沿堆体斜坡边界处氧的浓度较大,而在堆的中央部分,氧气的浓度非常小,导致这部分区域浸出反应缓慢;沿浸堆边坡处的温度偏低,温度最高的部分在底部区域附近靠近边坡位置处,且温度升高值超过6℃;矿堆底部靠近边坡区域目的金属离子浓度最高;靠近底部和斜坡部分,浸出反应速率快、氧化转化率高.矿堆的其余部分,因氧浓度低,导致浸出反应速率缓慢、氧化转化率低.

预处理-堆浸-萃取石煤湿法提钒室内扩大试验研究

本文是在进行预处理-堆浸-萃取室内小试的基础上又进行了吨级的室内扩大试验,主要对小试相关相关参数进行验证和确定,室内扩大试验对小试中难以测定的相关重要参数进行确定,同时还介绍了预处理工艺和设备,堆浸工艺和设备,萃取工艺和设备,对最终产品V_2O_5进行了检验,产品达到国家冶金级99产品要求,最后对废水进行了处理及检验,废水达到了国家排放标准。

HZD-4000弧形堆料机的皮带运输系统探讨

介绍了HZD-4000弧形堆料机与皮带运输机有关的主要参数。通过对该机皮带运输机主要设计参数的探讨,表明HZD-4000弧形堆料机的皮带运输机完全能够满足堆浸工艺的需要,并从中试制了1种新型的矿山堆料机。

世界上最大的铜矿山-智利埃斯科地达铜矿山

智利埃斯科地达(Escondida)铜矿山是世界上目前最大的铜矿山,具有世界上最丰富的铜资源。根据2009年资料,该矿山的铜矿石储量为41.57亿t,铜品位0.76%,其中含铜3156.7万t铜,矿石资源量为46.50亿t。矿山规划中采用的矿石储量为6.62亿t,其铜品位为2.12%。是世界铜矿山的生产成本最低的企业之一。矿山采用常规露天开采方法。平均每天开采24万t/d高品位硫化矿、4万t/d低品位硫化矿和3.5万t/d氧化矿。矿山由两个露天采场、两个选矿厂、一个氧化矿堆浸场、一个低品位硫化矿生物堆浸场和一个溶剂萃取/电极厂组成。矿山设计铜年产量为120万t。硫化矿选矿厂采用磨矿-浮选流程,得到含金和银的铜精矿。精矿铜品位为38%～43%,回收率为84%～86%。氧化矿堆浸采用破碎-制球-堆浸工艺。低品位硫化矿采用破碎-制球-筑堆-生物堆浸工艺。堆浸场得到的贵液送溶剂萃取/电积厂处理,得到阴极铜。堆浸场对氧化矿石堆浸的铜浸出率分别为80%和54%(对可溶性铜),堆浸场对低品硫化矿石堆浸的铜浸出率分别为37%和29%(对全铜)。矿山和选矿厂基本投资为56.4亿美元,而矿山铜的直接操作费用仅为60.8美分/磅铜。

S7-300在黄金堆浸微机监控系统中的应用

堆浸是黄金生产中普遍采用的提金工艺。以西门子S7- 30 0PLC为控制核心 ,设计了 1套微机监控系统 ,实现黄金堆浸过程中加药和喷淋的自动控制 ,给出了S7- 30 0的控制流程以及S7- 30

高铁离子和淋-停时间比对堆浸过程的影响

本文研究了坚硬、性脆、致密的火山岩型铀矿石堆浸过程中高铁离子和淋滤方式的影响。用统计数学方法处理数据,求得10g/L Fe^(3+)+5g/L H_2SO-4溶液和5g/L H_2SO_4溶液分别作淋浸剂的浸出速率比为。不同淋-停比时,浸出率与矿石粒度的关系为:。用高铁溶液作淋浸剂,并选择适当的淋-停比是缩短堆浸周期、提高经济效益的有效措施。