Warning Signs to Geotechnical Failure of Mining Structures

Mining structures, such as open pits and underground mines, tailings dams and waste rock dumps, under stress can suffer geotechnical damage and fail. Studies were carried out on large scale failures in a form of rock mass collapse (collapse of an open pit slope and a surface crown pillar), seismic events (rockburst and gas outbursts), mine inundation, and waste rock material instability (tailings dams and waste rock dumps).

The case studies revealed that geotechnical failure of mining structures were preceded by warning signs like indicators and precursors and that the failures were triggered by external factors like rainfalls or mine blasting. For large scale geotechnical failures, the initial precursors were present months or even years before failure. During the period from the initiation of structural damage to the final failure many various types of precursors were commonly reported and the number and scale of precursors increased towards impending failure. In a number of cases it was found that large scale geotechnical failures were preceded by a succession of small scale failures.     

Valorisation of acid mine drainage treatment sludge as remediation component to control acid generation from mine wastes,part 1: Material characterization and laboratory kinetic testing

In operating mines, acid mine drainage (AMD) is often treated using lime treatment. This process generates a significant amount of sludge that contains metal hydroxide precipitates, gypsum, and unreacted lime. The sludge may have interesting geotechnical and geochemical properties to be used as a part of covers (oxygen barriers) to prevent AMD generation from waste rocks and tailings. The main results of a project aiming to evaluate the use of sludge from the Doyon mine site (Canada) as a material in mine site rehabilitation are presented. The first part of the project involved detailed characterization of sludge, waste rock, and tailings samples. Then, laboratory column leaching tests were performed to evaluate the performance of the mixtures to control AMD produced by tailings and waste rocks. It was found that a sludge–waste rock mixture placed over waste rock reduces the metal loads in the column effluent, which remained acidic, as well as a mixture of sludge and tailings deposited over tailings can reduce metal content in effluents from tailings.     

Prediction of soil erosion from waste dumps of opencast mines and evaluation of their impacts on the environment

The volume of mine waste rock generated, including tailings from mineral processing activities, is one of the main pollution concerns in the mining industry in general. In the State of Goa (India), the waste rock management is becoming increasingly difficult due to acute space shortage consequent to expanding mining activities. These waste rocks contain acid producing sulphides and high concentrations of heavy metals. In the Goa region, the agricultural fields, nallahs, river beds and creeks are prone to heavy siltation/sediment deposition, which results from soil erosion due to the heavy rainfall this region receives. In view of this erosion and consequent degradation of surrounding environment, this article seeks to estimate the amounts of soil erosion from mine waste rock dumps using the RUSLE model and evaluates the impacts of erosion on the local environment. Based on data interpretation and RUSLE analysis, the trends in soil loss were established under various geo-environmental conditions, such as different slope angles and lengths. This provides a sound basis to plan and implement sound environmental management practices for mine waste rock in the mines of Goa, India.     

矿山排土场和尾矿库联合共建技术及其工程应用

尾矿库和排土场是矿山生产过程中的重大危险源,其安全性、经济性关系到矿山工程的成败,非常重要。在总结分析国内几种废石和尾矿联合处置经验的基础上,提出了一种排土场和尾矿库联合共建堆存的方法。为了解该方法的有效性及合理性,采用有限单元法和极限平衡法对该尾矿坝的应力变形和稳定性进行了分析。研究结果表明,排土场和尾矿库联合共建具有坝体稳定性好、安全性能高、经济效益好等优点,极端工况下坝体安全系数为1.21。研究成果对今后排土场和尾矿库共建相关的研究、设计和施工具有指导意义。     

某大型矿山现状排土场的稳定性分析

随着多年的露天开采,一些排土场达到服务期限停止使用,如何安全的对其进行关闭处置,成为矿山必须要完成的任务。为准确分析某排土场的稳定性,根据现场调查及工程勘察分析了现状排土场稳定性的影响因素,采用geo slope软件对排土场边坡不同工况下的稳定性进行了计算,计算表明该多台阶排土场整体稳定性良好,并针对排土场局部缺陷提出了相应的安全措施,为下一步排土场关闭提供了依据。     

弓长岭铁矿排土场边坡稳定性评价

露天采矿剥离岩土的排弃和排土场的形成,关系到矿山生产安全和人员生命财产安全.排土场稳定性是露天矿安全评价的核心内容,也是矿山安全管理的重点.以弓长岭露天铁矿大阳沟排土场边坡为例,在岩土工程勘察和物理力学性质分析基础上,通过极限平衡法和有限单元法相结合,对排土场边坡危险剖面在正常工况和降雨入渗工况下的稳定性进行计算,剖析排土场坡体稳定特征,所得结论对现场排土场具有重要的指导价值和现实意义.     

Application of Pb-Zn tailings for surface paste disposal: geotechnical and geochemical observations

Surface paste disposal (SPD) technology has been investigated recently to solve the geotechnical (tailings dam failure) and geochemical (acid mine drainage formation) problems relating to tailings disposal. The tailings dam accidents occurred in the last few years have expedited the researches to search for safer tailings disposal methods in mining industry. The aim of this study is to investigate which parameters affect the geotechnical and geochemical stability of sulphidic paste tailings as SPD. The pH, EC and crack intensity of paste tailings placed in layers were measured to observe how the parameters affect their stability. In this study, it can be seen that solid concentration of the paste material increases above ~80 wt.%, and its shear strength is above 20 kPa. In addition, the pH values reduced from 7.4 to 6.6 and the EC values increased from 2.9 to 3.3 mS/cm in seepage water of the paste layers. According to these values, it can be said that there is a very low environmental risk using the SPD. Results showed the applicability of the SPD method by obtaining geochemical and geotechnical stability.     

高地震烈度下宽顶废石尾矿坝的动力响应分析

云南某尾矿库设计将排土场修整后作为尾矿坝,形成的宽顶废石坝最大坝高182m,坝顶宽度496m,尾矿坝处于8度地震烈度区。采用等效线性黏—弹性模型,对宽顶废石尾矿坝的动力响应进行分析,得出高地震烈度条件下坝体加速度、动应力及动力稳定性。研究结果对高地震烈度区尾矿坝工程建设具有指导意义。     

Reliability-based approach to the geotechnical design of tailings dams

Mine tailings dams are geotechnical structures that are designed to provide adequate and safe storage of tailings materials both during and after the end of mine life. The design of such structures is thus of utmost importance not only to the success of the mining operation, but more importantly to the safety of the surrounding environment such as freshwater resources, wildlife and community developments. This paper presents a reliability-based approach for the geotechnical design of mine tailings dams through a real life case study of a water retention tailings dam. The stability analysis is conducted with a hydromechanical, elasto-plastic finite difference model. The reliability analysis is carried out for three stochastic parameters namely the cohesion and friction angle of the dam core material as well as its hydraulic conductivity. The results are presented in the form of probability distribution functions of the generated factor of safety. The generated reliability indices are compared to target reliability indices to help evaluate the geotechnical design of the dam.     

清洁化无废矿山采矿工艺设计实践

在ENFI承担的云南驰宏公司深部资源矿山的开采设计中,采用了以全尾砂、水淬渣、废石和水泥为原料的膏体泵送充填采矿工艺,提出了将该矿建成尾砂不进库、废石不出坑的清洁化无废开采矿山的目标。     

废石中线法在强震区高尾矿坝建设中的应用

针对强震区高堆尾矿坝建设的特点,在总结分析国内尾矿坝抗震经验的基础上,提出了一套以废石中线法为主、多种加固措施为辅的筑坝思路。从渗流、稳定等方面,对拟建于云南某沟谷内的高堆尾矿坝的抗震能力进行了研究和分析。研究结果表明,废石中线法具有浸润线低、稳定性好、不易液化等特点,9级地震设防条件下坝体最小安全系数为1.096,能够满足相关规范要求。该成果对于今后地震区特别是强震区高尾矿坝的设计、建造以及抗震加固等具有指导意义。     

金属矿山场地人工土壤特征研究

根据金属矿山的露天采场、浸矿场、废石场、排土场、尾矿库等场地的地表物质特征,将金属矿山场地人工土壤分为基岩型土壤、废石型土壤、尾砂型土壤、尾泥型土壤、岩土型土壤、土岩型土壤、风化土壤和表土共八种类型,对每种类型人工土壤的地表物质特征、颗粒特征、污染特征和土地复垦特征进行系统分析,供从事矿山场地修复、土地复垦、生态恢复等专业的研究人员和管理人员参考。     

The development and application of a wind erosion model for the assessment of fugitive dust emissions from mine tailings dumps

The wind erosion of mine tailings is an air pollution concern that has not been investigated thoroughly. Indeed, there is no accurate method to predict fugitive dust emission strength of tailings dumps. This paper reports on the development of a wind erosion model based on the principles of physics. Unlike most wind erosion models developed for agricultural lands or sand dunes, this model takes into account the fluctuations in wind velocity. The model was designed to predict hourly dust emission rate of flat tailings dumps prone to wind erosion for air quality modelling purposes. The model was evaluated using wind tunnel data and field experiments which confirmed the validity of the model for crushed industrial materials. The model was further validated with field experiments undertaken by the authors at the Mantos Blancos mine in Chile.     

基于废石中线法的强震区高尾矿坝动力特性分析

为了解废石中线法应用于强震区高堆尾矿坝建设的动力特性及稳定情况,采用有限元方法对废石中线法尾矿坝体渗流、静力条件以及动力响应进行模拟。分析了坝体在地震荷载作用下的加速度响应、液化区范围及稳定性。计算结果表明,尾矿坝体浸润线低,9级地震设防条件下坝体液化区主要集中在库内,不能形成滑移通道;尾矿坝加速度反应较小,放大倍数为1.99;坝体动力时程最小安全系数为1.055,均能够满足相关规范要求。成果对于今后强震区高尾矿坝的设计、研究及抗震加固具有指导意义。     

Oil sands mine planning and waste management using mixed integer goal programming

Strategic mine planning and waste management are an important aspect of surface mining operations. Recent environmental and regulatory requirements make waste management an integral part of mine planning in the oil sands industry. The research problem here is determining the order of extraction of ore, dyke material and waste to be removed from a predefined ultimate pit limit over the mine life that maximises the net present value of the operation. We have developed, implemented, and tested a proposed mixed integer goal programming theoretical framework for oil sands open pit production scheduling with multiple material types. The formulation uses binary integer variables to control mining precedence and continuous variables to control mining of ore and dyke material. There are also goal deviational variables and penalty costs and priorities that must be set up by the planner. The optimisation model was implemented in TOMLAB/CPLEX environment. The developed model proved to be able to generate a uniform schedule for ore and dyke material. This is in line with recent regulatory requirements by Alberta Energy Resources and Conservation Board (Directive 074) which requires oil sands mining companies to develop life of mine plans which ties in to their in-pit tailings disposal strategy. It also provides a practical mining sequence that is consistent with mining oil sands deposit. Similarly, tradeoffs between achieving a goal and maximising NPV can be made.     

A Geotechnical Solution to Reduce Acid Mine Drainage Generation at Recreio Mine

Coal mining is frequently associated with acid mine drainage (AMD) generated by tailings and waste dumps containing sulphide minerals. A practical and economical alternative to minimise AMD generation is to avoid the contact between water and waste dumps using a compacted soil cover. This study evaluates the use of distinct raw materials as cover layers. The study area was an open pit coal mine in the south of Brazil. Geotechnical characterization, physical, chemical and mineralogical analyses were carried out on two different soils from this mine. Hydraulic conductivity tests were performed using Flexible-Wall Permeameter. The results obtained from the hydraulic conductivity tests for two compacted soils suggest their applicability as impermeable layers. Considering the operational aspects at the mine and the characteristics determined for the soils a new construction scheme for the dump site was suggested.     

矿山生态修复及考核指标

首先提出了矿山生态修复的概念,通过对矿山露天采场、废石场、尾矿库、塌陷地、工业场地、道路管线、办公生活区、受污染水体和土地的土地特征、时空变化特点、生态修复主要制约因素分析, 根据矿山不同场地生态修复特点,从全过程角度出发,提出矿山生态修复考核指标,该考核指标具有较强的可操作性和实用性。     

Reinforced terraced fields method for fine tailings disposal

New mining technologies can exploit low-grade ores but they produce high volumes of waste, such as tailings. Further, current mineral processing techniques produce more and more fine tailings. How to dispose of these tailings is a key issue in the sustainable operation of a mine. A traditional method is to construct a settling or tailings pond for storage. Such a method requires sufficient coarse particles to raise a dam or embankment. However, the fine tailings contain little coarse particles and have poor mechanical properties. The stability of a tailings dam thus becomes a major issue if the traditional method is used. According to statistical data, all fine tailings dams or ponds in China have failed or have failure potential. Therefore, fine tailings disposal is a challenge to mine operators and new disposal methods should be explored for the stability improvement of tailings dams. In this paper, an innovative method of reinforced terraced fields is presented to satisfy the specific requirement of fine tailings disposal. By using an actual mine, this paper reports in detail the design concept and procedures for this method. Its feasibility is evaluated and its fundamental are analyzed.     

尾矿安全回采工程实践

矿山固体废物资源化已然成为矿山发展的战略目标。以某矿山为例,重点介绍了尾矿回采方案,计算了回采时坝体稳定性、采坑边坡安全系数,并提出防排水措施,为尾矿安全回采提供工程实践经验。     

一种新型尾矿废石联合排放方法

我国200~300 m级的大型排土场和尾矿库逐渐增多,占用大量土地资源,同时给下游居民设施带来很大的威胁。研究安全、经济的尾矿—废石联合堆放方法可以节约大量土地,具有重大的经济和环境效益。针对一种新型的尾矿废石联合排放方法—废石格网,从应力变形、渗流固结的角度对废石与尾矿的相互作用进行了理论分析和基于有限元和极限平衡条分法的数值模拟,结果表明废石体的合理布置可以有效降低尾矿库深部尾矿的渗流路径,加速尾矿排放过程中累积超静孔压的消散,显著降低坝体浸润线,提高滑裂面经过土体的抗剪强度,提升尾矿坝的抗滑稳定性。