Long-term Performance and Costs for the Anna S Mine Passive Treatment Systems

AMD from the Anna S coal mine in Pennsylvania (USA) has been treated successfully since 2004 in the Anna and Hunters Drift (HD) passive systems. The systems, which consist of vertical flow ponds and constructed wetlands, are the largest and most costly mine water treatment project installed by a non-profit group in the USA to date. 15 years of monitoring data show that the systems effectively treated 1910 L/min of flow with pH 2.8–3.1 containing 121–330 mg/L acidity (as CaCO3), 11–31 mg/L Al, 6–33 mg/L Fe, and 6 mg/L Mn. The systems produced effluents with pH 7.5, 134–140 mg/L alkalinity (as CaCO3), < 1 mg/L Al, 1 mg/L Fe, 2–3 mg/L Mn, and never discharged water with less than 60 mg/L alkalinity (106 samples). In 15 years of operation, the systems generated a combined 5600 tonnes (t) of net alkalinity. Unit treatment costs were converted to 2018 U.S. $ and compared to active treatment systems. Over a 20 year period, passive systems generate alkalinity at a cost of $1168/t of CaCO3, which is 50% less than unit costs for lime treatment plants currently operated in Pennsylvania.     

Potential for Passive Treatment of Coal Mine-derived Acid Mine Drainage in Abandoned Stream Channels

Mine Water and the Environment - Passive treatment of coal mining derived acid mine drainage (AMD) utilizes natural processes to neutralize acidity and remove dissolved metal contaminants. In some...     

Review of Passive Systems for Acid Mine Drainage Treatment

When appropriately designed and maintained, passive systems can provide long-term, efficient, and effective treatment for many acid mine drainage (AMD) sources. Passive AMD treatment relies on natural processes to neutralize acidity and to oxidize or reduce and precipitate metal contaminants. Passive treatment is most suitable for small to moderate AMD discharges of appropriate chemistry, but periodic inspection and maintenance plus eventual renovation are generally required. Passive treatment technologies can be separated into biological and geochemical types. Biological passive treatment technologies generally rely on bacterial activity, and may use organic matter to stimulate microbial sulfate reduction and to adsorb contaminants; constructed wetlands, vertical flow wetlands, and bioreactors are all examples. Geochemical systems place alkalinity-generating materials such as limestone in contact with AMD (direct treatment) or with fresh water up-gradient of the AMD. Most passive treatment systems employ multiple methods, often in series, to promote acid neutralization and oxidation and precipitation of the resulting metal flocs. Before selecting an appropriate treatment technology, the AMD conditions and chemistry must be characterized. Flow, acidity and alkalinity, metal, and dissolved oxygen concentrations are critical parameters. This paper reviews the current state of passive system technology development, provides results for various system types, and provides guidance for sizing and effective operation.     

Long-term Performance of Passive Acid Mine Drainage Treatment Systems

Abstract.   State and federal reclamation programs, mining operators, and citizen-based watershed organizations have constructed hundreds of passive systems in the eastern U. S. over the past 20 years to provide reliable, low cost, low maintenance mine water treatment in remote locations. While performance has been reported for individual systems, there has not been a comprehensive evaluation of the performance of each treatment type for a wide variety of conditions. We evaluated 83 systems; five types in eight states. Each system was monitored for influent and effluent flow, ph, net acidity, and metal concentrations. Performance was normalized among types by calclating acid loading reductions and removals, and by converting construction cost, projected service life, and metric tonnes of acid load treated into cost per tonne of acid treated. Of the 83 systems, 82 reduced acid load. Average acid load reductions were 9.9 t/yr for open limestone channels (OLC), 10.1 t/yr for vertical flow wetland (VFW), 11.9 t/yr for anaerobic wetlands (AnW), 16.6 t/yr for limestone leach beds (LSB), and 22.2 t/yr for anoxic limestone drains (ALD). Average costs for acid removal varied from $83/t/yr for ALDs to $527 for AnWs. Average acid removals were 25 g/m²/day for AnWs, 62 g/m²/day for VFWs, 22 g/day/t for OLCs, 28 g/day/t for LSBs, and 56 g/day/t for ALDs. It appears that the majority of passive systems are effective but there was wide variation within each system type, so improved reliability and efficiency are needed. This report is an initial step in determining passive treatment system performance; additional work is needed to refine system designs and monitoring.     

Iron Removal by a Passive System Treating Alkaline Coal Mine Drainage

The Marchand passive treatment system was constructed in 2006 for a 6,000 L/min discharge from an abandoned underground bituminous coal mine located in western Pennsylvania, USA. The system consists of six serially connected ponds followed by a large constructed wetland. Treatment performance was monitored between December 2006 and 2007. The system inflow was alkaline with pH 6.2, 337 mg/L CaCO₃ alkalinity, 74 mg/L Fe, 1 mg/L Mn, and <1 mg/L Al. The final discharge averaged pH 7.5, 214 mg/L CaCO₃ alkalinity, and 0.8 mg/L Fe. The settling ponds removed 84% of the Fe at an average rate of 26 g Fe m⁻² day⁻¹. The constructed wetland removed residual Fe at a rate of 4 g Fe m⁻² day⁻¹. Analyses of dissolved and particulate Fe fractions indicated that Fe removal was limited in the ponds by the rate of iron oxidation and in the wetland by the rate of particulate iron settling. The treatment effectiveness of the system did not substantially degrade during cold weather or at high flows. The system cost $1.3 million (2006) or $207 (US) per L/min of average flow. Annual maintenance and sampling costs are projected at $10,000 per year. The 25-year present value cost estimate (4% discount rate) is $1.45 million or $0.018 per 1,000 L of treated flow.     

煤矿矿井水的处理与综合利用

文中阐述了矿井水的来源和水质特征,及不同类型矿井水的一般处理方法,分析了矿井水综合利用的意义,提出了综合利用的多种途径和应用实例。     

一体化反应器处理某煤矿矿井废水

在NaOH用量为83 mg/L,PAC用量为75 mg/L,PAM用量为4.2 mg/L的条件下,采用混凝沉淀与砂滤一体化反应器处理某煤矿高浓度SS（300~500 mg/L）矿井废水,处理后废水各项指标达到《污水综合排放标准》（GB 8978-1996）一级标准。该工艺一次性投资少、运行费用低、占地面积小、运行管理方便,在处理煤矿矿井废水方面具有较强的竞争优势。     

煤矿废水阶段性处理技术与循环利用

利用阶段性煤矿废水处理技术,通过对传统工艺的局部修改,有效的解决煤矿生产建设与环境保护之间的矛盾,并且通过处理后的合格水的循环利用,降低了生产成本,减少了废水的排放量,显示出了良好的经济、环境及社会效益。     

Synthesis of a Goethite Pigment by Selective Precipitation of Iron from Acidic Coal Mine Drainage

Conventional treatment of acid rock drainage (ARD) from coal mines generates large volumes of sludge, which requires further treatment and disposal. The aim of this work was to study the recovery of iron by selective precipitation to synthetize goethite for use as pigment. Goethite particles were successfully produced, and presented a particle distribution in the range of nano- and micro-sizes, varying from 0.04 to 5.0 µm when produced as paste suspension, or from 0.04 to 25.0 µm when dried at 60?°C and converted to a solid powder. The pigment was used to color a white cement paste, giving it a yellow ochre color. ARD treatment plants can adopt this process to reduce waste disposal issues and produce a valuable mineral (e.g., yellow pigment for concrete).     

Influent Water Quality Affects Performance of Passive Treatment Systems for Acid Mine Drainage

Passive treatment of acid mine drainage (AMD) relies on biological, geochemical, and gravitational processes to neutralize acidity. Published design guidelines use sizing ‘rules of thumb’ based on AMD loadings at design flows. Using average performance data for 82 treatment systems, we used regression modeling to investigate the influence of influent net acidity and water loading on alkalinity generation by five treatment system types. Alkalinity generation increases with influent net acidity loading for all system types. Influent net acidity loading can be deconstructed into concentration and water loading components. In bivariate models, water loading was a predictor of alkalinity generation for all five system types but net acidity was significant only for vertical flow systems (VFs). In multivariate models using both components as performance predictors, both influenced alkalinity generation. These relationships were strongest for anaerobic wetlands (AWs), VFs, and open limestone channels; anoxic limestone drains and limestone leach beds demonstrated these influences less consistently. These results reflect the geochemical mechanisms governing the performance of limestone-based passive treatment system: solubility of limestone decreases as dissolved reaction products and pH increase.     

Passive Treatment of Acid Mine Drainage at the La Extranjera Mine (Puertollano, Spain)

In southern Spain, coal seams typically contain pyrite. The mines there are characteristically contaminated by the presence of diverse metals disolved in acidic water. An experimental passive system, containing an anoxic limestone draine, organic matter and wetlands, was constructed to assess how best to inprove the water chemistry. The procedure we used is reported on here so others can learn from what we did.     

Numerical Indices of the Severity of Acidic Mine Drainage: Broadening the Applicability of the Gray Acid Mine Drainage Index

The Gray acid mine drainage index (AMDI) was developed to detect, quantify, and categorise mine water and to monitor recovery of contaminated sites. A modified index (MAMDI) is proposed, incorporating the concentration of the dissolved metals that are present (at significant levels) and analysed at a site, and adjusting the weighting to reflect, in part, the maximum contaminant levels permitted by the U.S. EPA and WHO. In 98% of 206 analytical results applied to MAMDI, one or more of the four metals (Al, Zn, Cu, or Cd) used in AMDI were replaced by Mn, Ni, As, Pb, Tl, CN, and Be, while 63% had two or more replaced. A scatter diagram shows that in general, MAMDI is lower than AMDI when the total score is less than 50 and greater when the score is more than 50.     

Production of a Poly-ferric Sulphate Chemical Coagulant by Selective Precipitation of Iron from Acidic Coal Mine Drainage

The aim of this work was to produce a ferric sulphate rich solution from acidic coal mine drainage that could be used as coagulant. Precipitating the iron at pH 3.8, followed by dissolution in sulphuric acid, produced a coagulant consisting of 12.4% iron and 1.3% aluminium. Water treatment tests proved that this coagulant was as efficient as the coagulant chemicals conventionally used in water treatment plants. The process can be easily incorporated into conventional AMD treatment plants, thereby reducing sludge waste issues and producing a valuable chemical reagent.     

煤矿自动排水系统的应用

介绍了以可编程控制器PLC监控平台为基础的自动化控制系统,在煤矿矿井排水系统应用。首次对煤矿自动化排水系统做出了简单的介绍,阐述了该系统的组成,并对煤矿自动化排水系统做出了相关的功能分析。     

石泉煤矿瓦斯抽采的可行性研究

介绍了石泉煤矿煤层瓦斯的赋存特征,通过分析瓦斯涌出量及其渗透特性,论述了其瓦斯抽采的可行性,设计了工作面瓦斯预抽放的系统,并对其抽放系统的成本、经济及社会效益进行了统计和分析.说明该矿的瓦斯抽放可以保证工作面的安全回采,同时可以有效利用瓦斯能源、保护环境,具有较好的经济效益和社会效益,不仅解决了该矿的瓦斯问题,还可为其他类似矿井的瓦斯抽放提供参考.     

煤矿主排水自动化控制系统的研究

本文根据煤矿排水系统的特点,提出主排水自动化控制系统应具备的功能,并对其控制原理和控制核心部分、传感器和数据采集、执行部分进行论述,为实现煤矿排水系统的管、控、监一体化提供技术保证。     

基于S7-200型PLC的矿井主排水自动控制系统

鉴于煤矿采区泵房在矿井安全中的重要地位,设计了一种基于PLC和MCGS的井下泵房监控系统.该系统利用PLC抗干扰能力强以及MCGS人机交互性好等特点,通过传感器和检测元件,实现了对水泵的监控.该系统已成功运用于某矿采区泵房监控中.     

基于S7-1200的煤矿自动化排水系统设计

以PLC控制器作为核心,设计煤矿自动化排水系统,实现井下排水系统的自动化。通过交换机传递控制器处理过的传感器采集的信息,主机系统监控井下各设备的实时状态,并控制设备自动化运行。该系统具有自动、半自动、手动、远程等多种控制模式。应用实践证明,该系统安全可靠、功能完善,可满足不同环境的要求。     

Effects of Solid-Phase Organic Carbon and Hydraulic Residence Time on Manganese(II) Removal in a Passive Coal Mine Drainage Treatment System

Mine Water and the Environment - Passive treatment is a cost-effective method for Mn(II) removal from coal mine drainage via microbial oxidation and abiotic sorption/oxidation by Mn oxide (MnOx)....