Chemical Changes in Sediment Pore-Waters of an Acidic Mining Lake After Addition of Organic Substrate and Lime for Stimulating Lake Remediation

In the past five years, enclosures have beeninstalled in an acidic mining lake in Lusatia to investigate insitu remediation processes. They were treated with straw, withstraw and Carbokalk, or with Carbokalk alone, where Carbokalkis a by-product of the sugar industry (solid precipitate ofnon-sugars after lime clarification of extracted sugar beetjuice). Sediment samples were taken as cores to get informationabout the behaviour of organic and inorganic components insediment pore-water with depth. Vertical distributions of pH,soluble reactive phosphate, nitrate, ammonium, silica,aluminium, iron, manganese, calcium, magnesium, sodium,potassium, sulphate, and DOC were measured. The resultingprofiles, each consisting of 15 data points at differentdepths, were compared by cluster analysis. The similarities ofsediment cores from different treated enclosures relating toprofiles of chemical components were discussed. Increasedconcentrations of potassium and sulphate were found in pore-water after substrate treatment. The data imply dissolution ofpotassium iron sulphate hydroxide minerals (jarosite) after anincrease of pH caused by dissolution of lime and by sulphatereducing processes which were stimulated by organic substrateaddition.     

Locational Probability for a Dammed, Urbanizing Stream: Salt River, Arizona, USA

/ Data from historical aerial photographs analyzed with a GIS show that river channel change on the Salt River in the Phoenix metropolitan area of central Arizona has been driven by large-scale regional flood events and local human activities. Mapping of functional surfaces such as low-flow channels, high-flow channels, islands, bars attached to channel banks, and engineered surfaces shows that during the period from 1935 to 1997, the relative areal coverage of these surfaces has changed. Flood events have caused general changes in sinuosity of the low-flow channel, but islands have remained remarkably consistent in location and size, while channel-side bars have waxed and waned. The most important determinant of local channel form and process is sand and gravel mining, which in some reaches occupies more than 70% of the active channel area. The general location of mining is closely related to the location of the moving urban fringe, which serves as a market for sand and gravel during construction. Quantitative spatial analysis of imagery supplemented by field mapping shows that for each location within the general channel area, it is possible to specify a probability of encountering a low-flow channel or other fluvial features. Maps showing the distribution of these probabilities of occurrence reveal the most probable location and configuration of the channel as it occurred in the past. Some reaches have the low-flow channel located persistently within a limited area as a result of bedrock or sinuosity controls, but other reaches dominated by flow separation or shallow gradient have almost no persistence in channel location from one flood to another.     

WATER USE AND WATER CONSERVATION BY THE COPPER MINING INDUSTRY1

ABSTRACT: This paper examines the use of water by copper mines for treating low grade ores. The froth flotation process for treating sulphide ore and the heap leaching process for treating oxide ore are described, and ways of reducing the amount of water used in these processes are discussed. Estimates of the costs reducing water consumption are given. Finally, the circumstances in which it would be desirable for a copper mine to reduce its level of water consumption are considered.     

Microbial cycling of iron and sulfur in acidic coal mining lake sediments

Lakes caused by coal mining processes are characterized by low pH, low nutrient status, and high concentrations of Fe(II) and sulfate due to the oxidation of pyrite in the surrounding mine tailings. Fe(III) produced during Fe(II) oxidation precipitates to the anoxic acidic sediment, where the microbial reduction of Fe(III) is the dominant electron-accepting process for the oxidation of organic matter, apparently mediated by acidophilic Acidiphilium species. Those bacteria can reduce a great variety of Fe(III)-(hydr)oxides and reduce Fe(III) and oxygen simultaneously which might be due to the small differences in the redox potentials under low pH conditions. Due to the absence of sulfide, Fe(II) formed in the upper 6 cm of the sediment diffuses to oxic zones in the water layer where itcan be reoxidized by Acidithiobacillus species. Thus, acidic conditions are stabilized by the cycling of iron which inhibits fermentative and sulfate-reducing activities. With increasing sediment depth, the amount of reactive iron decrease, the pH increases above 5, and fermentative and as yet unknown Fe(III)-reducing bacteria are also involved in the reduction of Fe(III). Sulfate is reduced apparently by the activity of spore-forming sulfate reducers including new species of Desulfosporosinus that have their pH optimum similar to in situconditions and are not capable of growth at pH 7. However, generation of alkalinity via sulfate reduction is reduced by the anaerobic reoxidation of sulfide back to sulfate. Thus, the microbial cycling of iron at the oxic-anoxic interface and the anaerobic cycling of sulfur maintains environmental conditions appropriate for acidophilic Fe(III)-reducing and acid-tolerant sulfate-reducing microbial communities.     

The dynamics of artisanal and small-scale mining reform

Artisanal and small‐scale mining are activities that have long been established in many developing countries, employing millions of people globally, either directly or in affiliated industries. Also, such activities are deplored for their adverse environmental impacts and their general avoidance of governments, tax collectors and other regulators. Decades of work have gone into addressing these problems, but with limited overall progress in evidence. Going back to some of the key dynamic relationships involved in artisanal mining and small‐scale mining, the need for policy reform that gives consistent and effective incentives is argued to be the foundation on which other discussions about environmental protection, sustainability and livelihoods can be built.     

关于综放开采技术安全问题的几点认识

本文从放顶煤开采的一次采高大、上覆岩层的活动范围大、破碎顶煤的存在等基本特征出发,论述了关于放顶煤开采中瓦斯、顶板和冲击地压等安全问题.放顶煤开采对有些安全问题可以缓解,比如工作面的瓦斯突出.但是也可能诱发一些安全问题,如坚硬顶板对支架的冲击、采空区垮落岩石的撞击与摩擦诱发瓦斯事故等.在放顶煤大面积推广应用的同时,更应重视其相应的安全问题的系统研究与解决.     

枣庄矿区自营铁路安全现状分析及对策

按枣庄矿区十年发展规划,未来十年矿区煤炭产量将达到1800万t,矿区自营铁路煤炭外运将突破1000万t.为实现枣矿集团大集团战略目标,本文从矿区自营铁路运营现状及影响安全运输能力提高的瓶颈进行调研分析,并以此为依据提出提高矿区铁路安全运输能力的对策.     

Ammonia large scale atmospheric dispersion experiments in industrial configurations

A programme of large-scale experiments for atmospheric dispersion was carried out by INERIS over a period extending from December 1996 to April 1997. The objectives of the test campaign were to measure anhydrous ammonia concentrations in a range of few meters to 2 km from the release, in order to generate data to be used to improve 2-phase discharge and dispersion modelling.

The discharges were released from a 6-tonne storage tank of pressurised liquid ammonia and through a discharge device with an outlet diameter of 2 in. Fifteen trials were carried out with various release configurations corresponding to industrial situations (impinging jets on the ground and on a wall at various distances, release through a flange without seal…). The quantity of ammonia discharged from the liquid phase varied according to the tests, from 1.4 to 3.5 tons for durations between 7 and 14 min and, therefore, at flow rates between 2 and 4.5 kg/s. Approximately 200 sensors were settled downwind to measure ammonia concentrations and temperature in the plume. These tests showed that for discharges with identical flow rates the distances corresponding to the same concentration vary a lot according to the configurations. These distances tend to be reduced by the presence of obstacles or retention dikes that collected liquid ammonia. In the paper, the main experimental results are presented. In order to enable the comparisons with numerical predictions, more detailed information are given in [Bouet R. (1999). Ammoniac—Essais de dispersion atmosphérique à grande échelle. INERIS rapport, ref INERIS-DRA-RBo-1999-20410 (available at http://www.ineris.fr/recherches/recherches.htm).     

煤炭行业推行清洁生产的紧迫性及对策研究

通过对煤炭资源开发利用特征及其对生态环境破坏的现状分析,说明煤炭开采造成的生态破坏已成为我国可持续发展的制约因素.分析了煤炭行业推行清洁生产的必要性,并根据当前煤炭行业清洁生产中存在的问题,提出相应的对策.     

煤岩瓦斯复合动力灾害机理研究进展与展望

随着我国煤矿快速进入深部开采,煤岩瓦斯复合动力灾害日渐成为威胁深部煤炭安全高效开采的重大灾害,研究其发生机理成为煤矿安全领域新的重大科学问题。本文首先在调研统计的基础上,阐述我国煤岩瓦斯复合动力灾害的发生规律和主要破坏特征,从定性和初步定量研究角度对煤岩瓦斯复合动力灾害机理的研究现状进行综述分析,然后介绍笔者近年来在受载含瓦斯煤岩组合体耦合失稳诱发复合动力灾害机制方面的研究进展,最后展望煤岩瓦斯复合动力灾害机理研究中亟待解决的问题及未来研究方向。