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Sheng Peng 《Frontiers of Earth Science》2009,3(2):208-213
Heap leaching is essentially a process in which metals are extracted from mine ores with lixiant. For a better understanding
and modeling of this process, solute transport parameters are required to characterize the solute transport system of the
leach heap. For porous media like leach ores, which contain substantial gravelly particles and have a broad range of particle
size distributions, traditional small-scale laboratory experimental apparatus is not appropriate. In this paper, a 2.44 m
long, 0.3 m inner diameter column was used for tracer test with boron as the tracer. Tracer tests were conducted for 2 bulk
densities (1.92 and 1.62 g/cm3) and 2 irrigation rates (2 and 5 L/ (m2·h−1)). Inverse modeling with two-region transport model using computer code CXTFIT was conducted based on the measured breakthrough
curves to estimate the transport parameters. Fitting was focused on three parameters: dispersion coefficient D, partition coefficient β, and mass transfer coefficient ω. The results turned out to fall within reasonable ranges. Sensitivity
analysis was conducted for the three parameters and showed that the order of sensitivity is β > ω > D. In addition, scaling of these parameters was discussed and applied to a real scale heap leach to predict the tracer breakthrough. 相似文献
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The extraction of mineral resources requires access through underground workings, or open pit operations, or through drillholes for solution mining. Additionally, mineral processing can generate large quantities of waste, including mill tailings, waste rock and refinery wastes, heap leach pads, and slag. Thus, through mining and mineral processing activities, large surface areas of sulfide minerals can be exposed to oxygen, water, and microbes, resulting in accelerated oxidation of sulfide and other minerals and the potential for the generation of low-quality drainage. The oxidation of sulfide minerals in mine wastes is accelerated by microbial catalysis of the oxidation of aqueous ferrous iron and sulfide. These reactions, particularly when combined with evaporation, can lead to extremely acidic drainage and very high concentrations of dissolved constituents. Although acid mine drainage is the most prevalent and damaging environmental concern associated with mining activities, generation of saline, basic and neutral drainage containing elevated concentrations of dissolved metals, non-metals, and metalloids has recently been recognized as a potential environmental concern. Acid neutralization reactions through the dissolution of carbonate, hydroxide, and silicate minerals and formation of secondary aluminum and ferric hydroxide phases can moderate the effects of acid generation and enhance the formation of secondary hydrated iron and aluminum minerals which may lessen the concentration of dissolved metals. Numerical models provide powerful tools for assessing impacts of these reactions on water quality. 相似文献
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The recovery of uranium from an acid heap leach liquor has been investigated. Tertiary amines (tri-n-octylamine) have been chosen as extractants because of their high selectivity and efficiency. According to the theory of the mechanism of extraction by amines, an equation has been proposed for the extraction isotherms of uranium. In amine extraction systems the organic-aqueous volume ratio is more important for uranium extraction efficiency than amine concentration. Equilibrium data are further developed according to the McCabe-Thiele approach to calculate from extraction isotherms and stripping isotherms the number of theoretical stages. Three stages and two stages respectively are predicted for extraction and stripping circuits with an over-all uranium recovery of 98.9%. 相似文献
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二氧化碳(CO2)地质封存技术作为深度减排不可或缺的必要手段,对保护生态环境、推动全球中长期应对气候变化的国际合作以及推进社会绿色、循环、低碳发展具有重要意义。文章总结了二氧化碳地质封存项目全生命周期中可能出现的46个风险因素,运用社会网络分析方法构建风险网络关系模型,对二氧化碳地质封存项目风险因素间的传递作用关系进行了研究。通过风险网络整体与局部参数分析确定风险传递过程中的关键起始节点、关键致险节点、关键传递节点等关键因素,识别出三条潜在风险传递链：(1)地质灾害风险→CO2供应、注入或运输意外中断风险→预期外的建设或操作成本变化风险;(2)操作人员知识不足或无相应资质风险→人为泄漏风险→项目对环境的破坏风险→公众参与风险→预期外的建设或操作成本变化风险;(3)部门协调不当风险→人才招聘和管理风险→操作人员知识不足或无相应资质风险→预期外的建设或操作成本变化风险。研究旨在为二氧化碳地质封存项目风险研究提供理论创新与技术参考,进而促进CO2捕集、利用与封存项目的健康发展。 相似文献
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Currently depressed commodity prices have rendered many mining projects marginal irrespective of their geological merit. Tight capital markets discourage investment in their development because of their unappealing deterministic NPVs, which in the majority of cases reflect conceptual designs focused on achieving primarily economies of scale often at the expenses of operating flexibility. Given that project profits and cash flows are highly sensitive to movements in volatile commodity prices, circumstances now call for a re-direction of emphasis towards creating managerial flexibility to facilitate and minimize the cost of temporarily placing projects in care and maintenance and re-opening them in response to increases in prices. This flexibility, that is to say the option to alternatively switch the project between an open and closed state, can be created through an appropriate combination of mine design, commercial procurement arrangements and mode of operations that enables managers to anticipate and take advantage of future hikes in prices, while minimizing the negative effect of downturns. This paper presents a practical example of how to estimate the real option value (ROV) of this type of switching option, which is generally not captured by the deterministic DCF/NPV of projects. To facilitate the numerical presentation, initially the binomial lattice method is applied only to the first 2 years of a realistic DCF model of a gold mine, with an expected life of 5 years and a negative deterministic NPV. The model is limited to assessing the ROV created by introducing switching flexibility as a result of the volatility of the gold price in isolation. A consistent ROV is then obtained using as an alternative the unrelated decision tree methodology. This result is considered important as using decision trees for this type of analyses in cases where more than one source of uncertainty is involved (e.g. that of grades, costs, and exchange rates) does not require, as in the case of binomial lattices, estimating the volatility of a project cash flow. This process, which may create computational ambiguity and possible bias, can be avoided in decision trees as each source of uncertainty is represented by an individual event node. Finally the ROV of the project, including the switching option, is calculated over its whole 5-year life to provide some indication of the amount that could justifiably be invested up-front to create the necessary switching flexibility. 相似文献
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Johan Spross Lars Olsson Håkan Stille 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(3):183-189
The Swedish Geotechnical Society has adopted a general methodology for risk management in geotechnical engineering projects to reduce the costs related to negative outcomes of geotechnical risks. This technical note highlights the main features of the methodology and strives to inspire the international geotechnical community to apply sensible risk management methods. In the authors’ opinion, a successful geotechnical risk management needs to be structured, be tailored to the project, and permeate the engineers’ everyday work. Then, sufficient quality can be achieved in the project with larger probability. 相似文献
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F. Hahn 《Journal of Geochemical Exploration》1998,62(1-3)
Most geochemical engineering projects aim at commercial application. The proper economical analysis during the initial stages of the engineering process are of the utmost importance for the successful realisation of such projects. Many of the costs are committed at this stage. Important issues are: the scale of the project, the product quality and the choice of raw materials. For chemical plants, the Zevnik/Buchanan method is often used to make a rough estimation of the economic viability in an early stage. After the preliminary design of a geochemical process or other application has been completed, a more accurate estimation can be made by means of an economic balance. Guidelines for various costs are given in this article. Generally two criteria are used by companies to make a decision about further commercial realisation. One is the return on investment (R.O.I.), the annual profit divided by the total investment. The other is the pay-out time, the inverse of the R.O.I., the time needed to earn back the invested sum. This article provides geochemical engineers with some basic tools, that can be used to make an estimation of the economic potential of new geochemical engineering methods. 相似文献
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北京地区许多废弃的无主老矿山未实施矿山环境治理和土地资源恢复工程,矿区内地质环境和生态条件恶劣。本文对废弃矿山及其治理工程特点进行了分析,运用灰色关联度分析法,阐述了矿山废弃地土地资源破坏效应的四个因素——地表景观效应、土体污染效应、次生灾害效应、生态环境之间的联系。以房山区石窝大理石矿山废弃地治理工程为例,提出了矿山废弃地治理以矿山环境、灾害治理为主,以园林景观绿化为辅相结合的二维治理模式,在地形整治、挡土墙、绿化等措施的基础上进行园林景观的设计,结合周边居民生活需求,利用矿区内的正负地形渣堆和采石坑,进行景观的再生和组合,将采石坑设计成下沉式休闲公园和健身广场,希望通过园林景观绿化工程的实施,改善矿区及周边地表景观和生态环境。 相似文献
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N.R. Seifried 《Geoforum》1977,8(5-6)
Resource extraction projects in frontier regions may give rise to many problems concerning their economic viability and also their impact on the environment. The mining and processing activity in the oil sands of Alberta is a case in point. This area comprises one of the largest reservoirs of oil in the world. Long-run supply considerations in both Canada and the rest of the world should lead to further development of these oil sands. However, a review of the first two projects reveals considerable economic and environmental uncertainty. The economics of the project currently under way are questionable mainly because of inflated costs on one hand and uncertain future oil prices on the other. Controversy has developed over aspects of the land, water, and atmospheric environmental impacts of the projects partly because development proceeded before extensive studies were done. All these concerns have led to uncertainty concerning future projects and also the price the people of Alberta and Canada will pay, in economic and environmental terms, for development in this area. 相似文献
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岩堆是指陡峻山坡上,岩体崩坍物质经重力搬运,在山坡坡脚或平缓山坡上堆积的松散堆积体。拟建的宜巴高速公路线路方案穿越多处大型岩堆体,且地质条件复杂,各处岩堆体的密实程度各不相同。不同密实程度的岩堆体的强度和稳定性差异很大,对项目建设造成极大不利。为此进行了相同含水量不同密实度的岩堆体大型直剪强度特性实验,结果表明:岩堆体含水量、密度均存在很大的不均匀性,岩堆充填和胶结物含水量5% ~7%,平均含水量为6.5%,干密度最大值2.246gcm-3,平均天然密度为2.112g cm-3,平均干密度1.982g cm-3; 除干密度2.10gcm-3 试样在低垂直压力(50, 100, 200kPa)下分别出现剪切力峰值116.04, 154.7, 210.82kPa以外,其余各垂直压力下剪切力随水平剪切位移增大而增加,没有明显峰值,表现出明显的应变硬化特征; 岩堆体直剪强度指标c和随着其干密度的增加而增加,相同含水量下一般岩堆体越密实,其抗剪强度越高; 原始级配不同干密度下,随着岩堆体密实度增加,其抗剪强度对密实度的敏感性大幅度下降。 相似文献
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肖进 《地质灾害与环境保护》2011,22(2):65-70
以杨柳垭滑坡应急处置为例,研究控制推移式滑坡体变形成灾的途径。从变形特征、工程地质、处置过程和工程措施4个方面分析其应急措施。现场监测和数值模拟对各项工程的效果检验表明,推移式滑坡抢险可通过后缘减载、前缘堆载、抗滑桩和地表截排水,进行治理。 相似文献
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Mine-waste heaps are potential long-term sources of contamination for surface-water courses and groundwater systems. Application of a novel physically based particle-tracking model to a mine-waste heap in northern England, UK, has enabled predictions to be made of the lifetime of contaminants leaching, revealing a pattern of source-mineral depletion. A mine-waste heap is conceptualised by a series of one-dimensional unsaturated “columns” in which active weathering of source minerals takes place. These columns drain into a saturated zone, through which the contaminants are transported to the heap discharge. Solute transport is simulated within the model by the random-walk method while reaction kinetics are incorporated to account for the timescales of source mineral depletion. Results reveal that the mine-waste heap is likely to remain polluting for several centuries, with the governing factor in the magnitude of pollution being the transport of the reactant, oxygen, to the source-mineral surfaces. 相似文献
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加速发展地浸与堆浸技术开发我国的矿产资源 总被引：3，自引：1，他引：2
地浸与堆浸是当今世界上采冶开发低品位矿产资源最先进的技术。本文简要阐述了地浸与堆浸的基本概念及其优越性,论述了地浸与堆浸湿法冶金工艺研究的主要内容及该技术的发展与国内外应用现状,在阐述我国地浸与堆浸技术水平与国外相比存在的差距的基础上,提出了应用地浸与堆浸技术加速我国矿产资源开发的前景。 相似文献
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Until recently, research on potential economic impacts of climate change and extreme weather events on transport infrastructure was scarce, but currently this area is rapidly expanding. Indeed, there is a growing international interest, including the European area, regarding the impacts of extreme weather and climate change on the management of various transportation modes. This paper reviews briefly the present status regarding the knowledge of financial aspects of extreme weather impacts on transportation, using recent research findings from Europe, and proposes some new views in cost-benefit analysis, project appraisal and asset value protection for the management of transport systems under extreme weather risks. Quite often, risk management is understood as a response to truly extreme impacts, but this constitutes a misunderstanding. Some values are more extreme than others, and in the context of extreme weather, some weather phenomena are more extreme in their intensity and resulting impacts. An analysis of the level of costs and risks to societies, as a result of extreme weather, reveals that the risks in different European Union member states deviate substantially from each other. Also, the preparedness of different societies to deal with extreme weather events is quite variable. Extreme weather and climate change costs and risks represent a new type of item, which has to be dealt with in project appraisal. Although a fully established procedure does not exist, some fundamental ideas of cost-benefit analysis under extreme weather scenarios are presented in this paper, considering accident costs, time costs and infrastructure-related costs (comprising physical damages to infrastructures and increased maintenance costs). Cost-benefit analysis is usually associated with capital investments, but the original idea of cost-benefit analysis is not restricted to investment appraisal. Therefore, activities such as enhanced maintenance, minor upgrades, adoption of new designs, improved information services and others may be subject to cost-benefit analysis. Extreme weather and climate change costs and risks represent a new type of item, which apparently has to be dealt with also in project appraisal. A fully established procedure does not exist, although some basic principles have been introduced in analytical format. There is a lack of models to estimate extreme weather impacts and consequences and how to adapt to those costs. Optimising the efforts in maintenance and new design standards is even further away, but constitutes an overwhelming task. In this respect, new approaches and ways of thinking in preserving asset’s residual value, return periods, sustainability and equity and formal methods supplementing cost-benefit analysis are put forward. The paper concludes with a call for the need for more integrated management of transport systems. In particular, it is recognised that the different stages of transport system planning pose their own challenges when assessing the costs and benefits of policy measures, strategies and operational decisions. 相似文献
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传统双排桩单门架式支护结构是软土地区基坑支护设计中常用的一种支护手段,由于其施工简便、不需设置内支撑、投资小并节约场地而被经常采用。但在深厚软土超大型基坑且中等开挖深度时采用,往往会出现基坑侧向位移大、沉降大、结构稳定性差的问题。结合对传统门架式支护结构的改进,在软土大型中等深度开挖基坑工程中提出了不设内支撑的双门架式支护结构形式,进一步提高支护结构整体安全稳定性和控制支护结构侧向位移,通过将该结构设计应用于绍兴县一小区项目地下室基坑支护工程,验证了该改进方法的适用性和可行性,为今后类似工程提供了宝贵的经验。 相似文献
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加拿大、 美国多年冻土地区输电工程建设经验浅析 总被引：2，自引：2，他引：0
国际上有关冻土地区输电工程建设的成功经验, 对我国类似工程建设及相关问题的研究具有积极的借鉴意义. 重点以加拿大育空地区和美国阿拉斯加地区输电工程为例, 对国外冻土地区输电工程建设相关经验进行系统总结, 涵盖工程建设全过程, 即从工程前期准备到工程设计和建设直至工程建成后的运行维护. 基于此, 从完善工程评估机制、 建立和执行相关工程建设规范与技术标准、 工程建设环境风险控制以及确保工程运营安全等方面, 探讨了国外经验的可借鉴之处. 相似文献