A semi‐analytical approach for modelling heat transfer during salt‐cavern leaching process

The use of gas‐storage caverns in salt formations is a growing industry that continues to gain momentum because it allows gas to be injected and withdrawn at high rates compared with other underground gas‐storage systems such as porous rock systems. In order to predict cavern production performances, cavern thermodynamics behaviour must be studied by higher accuracy approaches. This behaviour is extremely related to the temperature distribution in the surrounding formations. During the leaching process, the thermal equilibrium of the rock salt surrounding the cavern is extensively disrupted. The purpose of this paper is to study the heat transfer problem during the leaching process and to develop a thermal model that can be easily used in field applications. The results of this work will be the input data for the prediction of the gas temperature and pressure during cavern gas‐storage operation phase. Moreover, the developed model can find its use in the design of salt caverns since it can be coupled with geometrical modelling of salt dissolution codes. Copyright © 2008 John Wiley & Sons, Ltd.     

河南新密—荥巩矿区煤矸石中有害微量元素的溶出

淋溶是有害微量元素从煤或煤矸石中析出后污染环境的重要途径。本文在对河南新密—荥巩矿区煤矸石淋溶实验的基础上,研究了有害微量元素从煤矸石中淋溶析出的浓度及淋溶过程中pH值的变化规律,探讨了不同淋溶实验方法对有害微量元素溶出的影响,并对有害微量元素溶出的环境意义进行了讨论。      

不同因素影响下突发性强降雨对沙拐枣的危害——以塔里木沙漠公路防护林生态工程为例

塔里木沙漠公路防护林生态工程全长436 km,造林树种以抗逆性较强的沙拐枣(Calligo-num L.)、柽柳(Tamarix L.)、梭梭(Haloxylon Bunge)等优良防风固沙灌木为主,采用高矿化度地下水滴灌.2005年5月,公路沿线出现了罕见的突发性强降雨,由此引起的表层土壤盐分淋溶造成了沙拐枣大量死亡.本研究采用线路调查和随机抽样方法,在突发性强降雨后对塔里木沙漠公路防护林带内沙拐枣死亡率进行了调查,并对调查结果及其原因进行了分析,结果表明:沙拐枣死亡率(1)随林龄的增加而减小;(2)随矿化度的升高而增大;(3)垄间平沙地>过渡区>高大沙垄垄体;(4)林带中央>公路旁>林带外围.     

江西大布铀矿床溶浸地质条件及溶浸方法研究

本文围绕溶浸采矿这个主题,从岩、矿石的物质成分;矿石结构构造;铀的存在形式;岩、矿石物理力学参数;矿体形态、产状、规模及矿床水文地质等方面阐述了大布铀矿床溶浸的天然地质条件,并通过一系列矿石铀浸出工艺试验,获得了大量溶浸工艺参数,提出大布铀矿床以原地破碎浸出辅以堆浸为最佳采矿方案。     

江苏省某地粘土型低品位金矿堆浸提金工艺探讨

简述了江苏某地粘土型金矿的地质特征、选矿工艺的选择。在重点论述矿山堆浸提金工艺流程的同时,论述了堆浸场的选择、底垫铺设、尾渣处理、矿区环境保护等矿山开发过程中的其他主要问题。通过四年的开发实践,矿山取得了较好的综合效益。     

陕西长武古土壤深部风化剖面与环境研究

根据作者提出的CaCO₃淀积深度理论、风化剖面的野外鉴别和室内CaCO₃、磁化率测定、粒度分析,确定了陕西长武第4、第5层古土壤底部之下存在深部风化黄土层和迁出了土壤层的CaCO₃结核层。这种风化黄土层和CaCO₃淀积层的发育表明当时风化淋滤作用超出了成壤带深度范围,指示长武第4、第5层古土壤为不具CaCO₃淀积层的中酸性、淋溶型森林土壤。该风化层代表了降水丰富的气候事件,当时年均降水量为900 mm左右。     

Factors influencing in-situ leaching of uranium mining in a sandstone deposit in Shihongtan,Northwest China

The Shihongtan uranium deposit in northwest China is a sandstone-type deposit suitable for alkaline in-situ leaching exploitation of uranium. Alkaline leaching tends to result in CaCO3 precipitation there by affecting the porosity of the ore-bearing aquifer. CaCO3 deposits can also block pumping and injection holes if the formulation parameters of the leaching solution are not well controlled. However, controlling these parameters to operate the in-situ leaching process is challenging. Our study demonstrates that the dissolved uranium concentration in the leaching solution increases as HCO3－ concentration increases. Therefore, the most suitable HCO3－ concentration to use as leaching solution is defined by the boundary value of the HCO3－ concentration that controls CaCO3 dissolution-precipitation. That is, the dissolution and precipitation of calcite is closely related to pH, Ca2+ and HCO3－ concentration. The pH and Ca2+ concentration are the main factors limiting HCO3－ concentration in the leaching solution. The higher the pH and Ca2+ concentration, the lower the boundary value of HCO3－ concentration, and therefore the more unfavorable to in-situ leaching of uranium.     

渭河沉积物浸出的水文地球化学效应研究

基于渭河咸阳段（中游）和渭南段（下游）沉积物在水更新条件下的浸出实验及水文地球化学模拟,分析了浸出液中3个特征值和8个水化学组分的变化规律及5种矿物质饱和指数的变化特征.结果表明：浸出液中电导率、Eh值和pH值均随着换水量的增加呈现出波动式上升的变化趋势,电导率增加趋势中咸阳段高于渭南段,Eh值增加趋势中渭南段高于咸阳段,说明渭河下游沉积物的颗粒更细,物质还原性更强,浸出液由弱酸性逐步向弱碱性转变;浸出液的HCO₃^-、Cl^-、SO₄^2-含量均表现出随着换水量的增加呈现出先迅速增加,而后逐步减少直至趋于稳定的变化过程,且咸阳段的变化幅度明显高于渭南段,而CO₃^2-含量则呈现不断减少的趋势;Ca²⁺、Mg²⁺、Na⁺、K⁺含量均表现出随着换水量的增加呈现出先迅速增加,而后趋于稳定的变化过程,且咸阳段的起始含量和增加幅度均高于渭南段;浸出液中无水石膏、石膏的饱和指数随换水量的增加呈现相同的变化规律,且饱和指数都小于0,咸阳段饱和指数在换水量小于22.5%时溶解能力强,换水量大于22.5%后趋于饱和并开始沉淀的特征,渭南段换水量为12.5%时饱和指数最小,换水量大于或小于12.5%后饱和指数均呈缓慢增加的趋势;方解石、白云石的饱和指数随换水量的增加也呈现相同的变化规律,且饱和指数都大于0,咸阳段在换水量小于12.5%时溶解能力较强,换水量大于12.5%后处于饱和状态并开始沉淀,渭南段在换水量小于5%时溶解能力较强,换水量大于5%后处于饱和状态并开始沉淀;NaCl饱和指数在换水量小于10%时溶解能力较强,换水量大于15%后开始沉淀.咸阳段沉积物中五种矿物质的饱和指数均要大于渭南段,说明渭河中游咸阳段沉积物在水不断更新条件下矿物质溶解能力低于下游渭南段,且沉淀能力较强、沉淀量较大.     

原地宇宙成因核素测年中石英样品分离提纯的几组实验对比

原地宇宙成因核素测年方法在地质及地理研究领域应用广泛,测年对象众多。石英因其致密的晶体结构不易被大气成因10Be污染,以及较低的27Al含量的特点而成为宇宙成因核素测年方法中一种理想的测年物质。在分离石英样品10Be和26Al的实验流程中,石英的提纯是其中的一个关键环节。原始的HCl/H2O2和HF/HNO3蚀刻分离提纯石英方法应用广泛、安全可靠,但处理样品周期长、效率较低。因此,在原始流程的基础上,设计了3组实验流程与原始流程进行对比。结果显示,在样品石英纯度较高的基础上,可以通过减少超声波使用时间、增加蚀刻溶液浓度及每步样品处理量的方法,提高样品的处理效率,同时可以用加热磁力搅拌器替代超声波清洗器进行石英样品的HF/HNO3蚀刻提纯     

泥旦沟金矿堆浸试验研究

泥旦沟金矿采用堆浸工艺,对低品位矿石进行提金试验。试验矿石品位2.25g/t,规模4795t。金的浸出率67.74％,单位矿石利润66.8元/t,经济临界品位降至1.23g/t,矿山服务年限得到有效延长。