铀堆浸废水中和沉渣减容与改性方法研究

在传统石灰中和处理法的基础上，提出了酸法难浸废水用“石灰石-石灰两步中和-沉渣循环”的流程进行处理。废水先与廉价的石灰石接触反应，使废水中的强酸中和并使铁、铝等金属离子在较低pH值下形成氢氧化物，再用石灰乳进一步中和到要求的pH。生成的沉淀物（沉渣）在过程中不断循环。该方法与一次石灰中和法相比，试剂费用节省1／3，沉渣生成量（以体积计）减少2／3，并且沉渣的过滤和沉降性能也有所改善。本工作还对沉渣减容与改性的机理进行了研究探讨。     

Water Cover Over Mine Tailings and Sludge: Field Studies of Water Quality and Resuspension

Flooding is considered one of the best available technologies for long term storage of acid generating mine waste when suitable site-specific conditions exist. There is, however, a concern that oxidation may still occur. In cases where lime neutralization sludge and reactive sulfide tailings are co-disposed in the tailings pond, wind-induced waves could resuspend the waste and negatively impact the quality of the water cover. Studies were undertaken at the Noranda Inc. Heath Steele Lower Cell tailings impoundment, located in northeastern New Brunswick, Canada, 50 km northwest of city of Miramichi. The stored material in the cell consisted of unoxidized tailings with small amounts of sludge. The 90 ha impoundment acted as a polishing pond, prior to the discharge of final effluent. The pond was keptalkaline (pH of 8.5-10.5) in order to meet regulated discharge limits. On some windy days when the Lower Cell experienced turbulent water conditions, the final effluent exceeded the suspended solids water quality standard of 25 mg/L. The dry mass of suspended sediment measured in 1999 ranged from 1.5 to 434 mg with relatively more material (> 100 mg) being suspended under shallow water cover (= 1 m). Both x-ray diffraction and scanning electron microscopy analyses indicated that the suspended material was mostly lime neutralization sludge and other material composed primarily of calcite and brucite and coatings of aluminum, iron, zinc and manganese hydroxides. Solubility considerations of the carbonate system confirmed that the water cover was supersaturated with respect to calcite. The results suggest that sludge and tailings re-suspension and precipitation of solid phases in the water cover likely combined to produce the observed, occasionally high total suspended solids concentration.     

Treatment of acid mine drainage through a ferrite formation process in central Hokkaido,Japan: Evaluation of dissolved silica and aluminium interference in ferrite formation

A two-step neutralization process, leading to the formation of ferrites has been developed for the treatment of acid mine drainage (AMD). In the first neutralization step magnesium oxide was used to raise the pH to around 4.5 to eliminate aluminium (Al) and to reduce the silica (Si) concentration. In the second neutralization step sodium hydroxide was used to complete the neutralization and to precipitate ferrous and ferric hydroxides, from which ferrite could be formed. The AMD of a closed gold mine in central Hokkaido, Japan was treated in a continuous-flow bench-scale plant of the process. During the first neutralization step the removal of Si was more difficult than the removal of Al; the presence of both Al and Si interfered in the ferritization of the sludge. When the Al removal decreased from 94.5% to 64.3% the magnetism per unit mass of the sludge was reduced by 36.7% and when the Al removal decreased to 21.8% the magnetism of the sludge was reduced by 51.5%. The interference of coexisting Si was even stronger: the sludge showed a 26% and 36.7% decrease in magnetism when the removal of Si was reduced by 15% and 18%, respectively.     

Enhancement of Sludge Sedimentation Properties in a Concentrated Acid Mine Drainage Using Nano- and Micro-magnetite Particles

Conventional treatment of AMD involves neutralization with consequent precipitation of metals as hydroxides. In AMD with a high concentration of metals, the settling rate of the sludge/water interface is low. We investigated the use of nano- and micro-magnetite particles to assist the settling and thickening of floc particles. The magnetite was produced from ferrous sulphate crystals (melanterite, Fe₂SO₄·7H₂O) obtained by leaching pyrite from a coal mine. AMD was obtained from the treatment plant at the same mine and the water was neutralized with Ca(OH)₂ at pH 8.7?±?0.1. Laboratory studies were conducted in 1 L test tubes with and without the addition of magnetite particles and a flocculant. Sedimentation curves (interface settling) were generated to evaluate the rate of sedimentation. For the studied effluent, the best option was 4 g L^?1 of magnetite particles and 5 mg L^?1 of high molecular weight anionic polyacrylamide. The magnetite particles were recovered magnetically from the sludge with ≈ 90% efficiency. Thus, the combined use of magnetite and a flocculant increased the sludge settling rate and, consequently, reduced the area needed for settling basins.

     

高密度泥浆法处理硫铁矿废水试验研究

高密度泥浆法(HDS法)是一种区别于传统石灰法、具有独特原理和特点的中和处理技术。采用高密度泥浆法对新桥硫铁矿废水进行了处理试验,研究了pH值、曝气、反应时间、沉淀时间、絮凝剂、底泥回流等对处理效果的影响。试验结果表明,采用HDS法,引入曝气工艺可使处理水质稳定达到排放标准,并得到了HDS法处理新桥硫铁矿废水的工艺参数,为工程设计提供了科学依据。     

Pilot-scale Studies of Different Covers on Unoxidised Sulphide-rich Tailings in Northern Sweden: the Geochemistry of Leachate Waters

Abstract.  Leachate water quality from covered and uncovered unoxidised sulphide-rich tailings in six pilot-scale (5x5x3 m³) test cells was monitored during 2004 and 2005. The covers consisted of a layer of clayey till, sewage sludge, apatite or Trisoplast (a commercial mixture of tailings, bentonite, and a polymer). All layers were protected by an unspecified till except in one reference cell, where the tailings were left open. All leachate waters showed near-neutral pH as a result of neutralization by calcite in the tailings and by Ca(OH)₂ added prior to deposition. Average dissolved sulphur concentrations in the leachates were ≈ 600 mg L^-1, except in the cell with sewage sludge (300 mg L^-1). The source of sulphur was mainly pyrite oxidation, but residual sulphur probably remained from the enrichment process. The near-neutral pH favoured precipitation of metal-(oxy)hydroxides with subsequent removal of trace elements such as Cd, Cu and Pb (< 15 μg L^-1) from the solutions. High concentrations of Co, Mn, Ni, and Zn were found in leachates from the apatite, Trisoplast, and uncovered tailings cells. High As concentrations were found in the leachates in the sewage sludge and clayey till cells. The lowest metal concentrations, redox potential, and highest pH were found in the sewage sludge cell. Decreased elemental metal concentrations during 2004 suggest improved performance over time.     

湿法回收氯化石灰中和渣中的锗

研究了回收氯化石灰中和渣中的锗的工艺,采用热水洗涤除钙、稀盐酸浸出锗除钙,洗涤浸出后的渣用两段逆流碱浸出锗.酸浸出液与一次碱浸出液混合并调节pH为2~2.5,用栲胶沉淀锗,焙烧沉淀渣得到锗精矿.采用此工艺从氯化石灰中和渣到锗精矿,锗的回收率可以达到90%以上.     

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.     

矿山酸性废水中和处理工艺优化研究

采用石灰中和酸性废水的矿山普遍存在氧化钙反应不彻底、污泥沉降性能不理想问题。为了提高氧化钙的利用效率、改善污泥的沉降效果,以某铜矿环保车间的废水为试样,进行了氧化钙直接中和废水工艺条件研究和污泥回流+氧化钙中和废水工艺条件研究。结果表明：①在氧化钙用量为24 g/L、消化时间为20 min、搅拌速度为400 r/min情况下进行氧化钙直接中和试验,反应75 min的料浆pH＞6。②在污泥（pH＞6）回流比例为40%、氧化钙用量为22.0 g/L情况下进行废水中和,也可将废水的pH调至6以上,且废水中金属离子浓度得到大幅度下降,满足送尾矿库储存的要求。③污泥的回流不仅可以充分利用其中未反应的氧化钙,减少新添氧化钙的用量,还可以改善污泥的沉降性能、提高污泥的固含量,有利于尾矿库回水的澄清。     

A study of the drainages of the pyrite mines of Aljustrel (Portugal)

Characterization of the pollution charge of drainages from pyrite mines of Aljustrel (Portugal) was made. Laboratory experiments were performed in order to recover copper by cementation and remove iron, zinc and acidity by neutralization with lime. It was found that the removal of the metal ions is completed when pH reaches a step at 5.0–5.5, whichever the ratio between Fe(II) and Fe(III).     

采用高密度污渣返回法处理铀矿山酸性废水的研究

介绍了采用高密度污渣返回法处理铀矿山酸性废水工艺流程。该流程与常规法比较,有以下优点:污渣沉淀速度快,压缩性能好,w (固体)高,没有返溶现象,并且石灰用量减少约20% 。从而解决了普通石灰中和法产生大量污渣及难以处置的问题     

Feasibility of lime treatment at the Leviathan Mine using the in-line system

The In-Line System (ILS) was used in a pilot-scale water treatment study at the Leviathan Mine in California. The Leviathan Mine is a remote, abandoned, copper/sulfur mine. This study addressed two questions: (1) Can the severely polluted mine drainage at the Leviathan Mine be treated with lime to an acceptable quality? and (2) Can a neutralizing reagent formulation (using various ratios of lime, fly ash, and cement) be designed to improve the physical characteristics of the resulting sludge for disposal purposes? The primary pollutants of concern are arsenic, nickel, aluminum, iron, and sulfate. Pilot-scale studies at the Leviathan Mine show that an in-line system (ILS) can be used to treat the severely polluted pond and adit water to meet the U.S. Environmental Protection Agency’s National Ambient Water Quality for Freshwater Aquatic Life Protection (1-hour acute toxicity) criteria. Lime and lime-based admixtures were used to neutralize the adit and pond waters. The optimal treatment pH range was 6.9–7.9 for adit water, and 6.5–8.0 for pond water. The ILS served as a neutralization and mixing system for treating both water sources, and also as an aeration system for treating the adit water. The ILS effectively oxidized nearly 900 mg/L of Fe⁺² within 30 seconds of contact time when treating the adit water. Additional work is needed to evaluate sludge alternatives. The simplicity, portability, flexibility, and economics of the ILS make it a prime candidate for remote treatment operations such as the Leviathan Mine. Furthermore, the ILS can operate by water power with elevational differences of 50 ft or greater. The need for permanent electrical power installation for water treatment can possibly be eliminated by coupling the ILS with a commercially available water-powered lime feed system.     

某矿山含铜酸性废水处理的工业实践

很多有色金属矿山在开发过程中,会产生大量含铜酸性废水。由于酸性废水含铜浓度差异性较大,采取的处理工艺也会有所不同。本文针对某矿山含铜酸性废水进行了大量的工业试验研究,结果表明：较高浓度含铜酸性废水可采取硫化法回收铜金属,再经环保中和处理后循环利用,可大量减少中和渣产生量,降低环保处理成本,有显著的经济、环保效益。同时,为了防范极端气候下的环境风险,该矿山还建设了足够处理能力的备用石灰中和处理系统以及应急液碱（片碱）加药系统,以供同类矿山参考、借鉴。     

Limestone Neutralisation of Arsenic-Rich Effluent from a Gold Mine

Traditionally acid mine water is neutralised with lime. Limestone is a cheaper alternative for such applications. A case study showed that limestone can be used effectively to replace lime for the neutralization of arsenic rich acid water. The cost of limestone treatment is 45.8% less than that of lime. The acidity can be removed from 33.5 to 0.06 g/L (as CaCO₃). The study also showed no significant differences in the TCLP characteristics of the resultant sludge when water is treated with lime or with limestone. Sludge from the limestone treatment process can be disposed of on a non-hazardous landfill site. An erratum to this article can be found at     

某多金属矿尾矿废水处理的试验研究

通过实验室小试得到处理某多金属矿尾矿废水的最佳方案。首先选用石灰作为脱稳剂进行脱稳,当调节废水pH值为11.5时,脱稳沉淀效果最好。然后选用阳离子型聚丙烯酰胺作为絮凝剂进行絮凝沉降,当阳离子型聚丙烯酰胺用量为2mg/L,pH值在8~9时,处理后废水能够达标排放。     

Integrating sulfidization with neutralization treatment for selective recovery of copper and zinc over iron from acid mine drainage

The most commonly used commercial process for acid mine drainage (AMD) treatment today is lime neutralization. However, it is accompanied by the treatment of produced metal hydroxide precipitate. Because of the decrease in the capacity of landfill disposal site and the increase in the price of base metals such as copper (Cu) in recent years, it is expected that not only to treat but also to recover these base metals from AMD. For the subsequent smelting process, the major issue is how to separate the Cu and zinc (Zn) over iron (Fe) from AMD as selectively as possible.In this work, we attempted to achieve this objective by modifying the present lime neutralization treatment process with sodium hydrosulfide (NaHS) sulfidization. An AMD sample generated from an abandoned copper mine located in east Japan was utilized in this study. At first, lime neutralization was applied to the AMD to find the precipitation behaviors of Cu, Zn, and Fe. Next, NaHS sulfidization as well as the integration with lime neutralization were conducted to separately precipitate Cu, Zn, and Fe from the AMD. Finally, two modified treatment approaches for selectively recovering Cu and Zn over Fe from the AMD were proposed. The results of consecutive experiments for the two proposed approaches showed that Cu, Zn, and Fe in the AMD were removed and separated into individual precipitates, and that the concentrations of each heavy metal in the final effluent were also able to meet the Japanese effluent standards.     

矿山酸性废水处理中的pH控制方法

介绍矿山酸性废水处理中pH控制的难点,描述石灰乳中和反应中药剂用量与pH的关系。结合pH控制的难点,阐述一种经济、可靠的石灰乳投加控制方法。通过应用该方法,经处理的废水优于国家规定的排放标准。     

Removal of trace elements from acid mine drainage

The mine drainages in some coal mines of North Eastern India, are found to be highly acidic and contain trace elements which are highly undesirable for drinking purposes. This water requires neutralization together with trace metal removal prior to its supply to the public. This paper describes the results of a study conducted to determine the ability of lime neutralization to remove inorganic trace elements from acid mine drainage under different operating conditions. The specified trace elements were arsenic, cadmium, chromium, copper, mercury, lead, zinc, manganese, aluminium, iron and nickel etc. Results of this study indicate that treatment by lime neutralization was very effective in removing these trace metals from acid mine drainage.     

氧化-控pH中和法处理南丹县吉朗铟业有限公司锌冶炼高酸含砷废水

针对石灰中和法处理南丹县吉朗铟业有限公司锌冶炼过程中高酸含砷废水,存在污泥量大、污泥处理困难、有价金属流失严重、成本高等缺点,研究采用氧化-控pH中和法处理锌冶炼过程中高酸含砷废水技术.多次试验表明,该工艺简单,技术成熟可靠,具有较好的推广应用的条件.     

Removal of Molybdenum from Mining-Impacted Water by Sorption onto Manganese-Rich Sludge

Molybdenum (Mo) concentrations in mining-impacted water can be orders of magnitude higher than health-based values for drinking water. Mo in oxidized mine waters is predominantly present as the oxyanion molybdate, which is problematic in mine water treatment because it is not removed by conventional alkaline addition treatment and requires separate Mo-specific methods. Mo removal by sorption to ferric precipitates is the typical treatment strategy. We investigated a sustainable alternative for a mine water with low-iron content and high manganese (Mn). We evaluate the potential for Mo removal by sorption onto Mn-rich sludge from a mine water treatment plant that uses lime to remove metals at pH 10. In laboratory sorption batch tests with an initial Mo concentration of 10 mg/L in a sodium chloride solution, over 90% of the Mo was removed onto the sludge at pH 6 and below (up to 34 mg Mo/g Mn). Sorption was sensitive to pH, with sharp decreases in sorption levels from pH 6 to 8. Sorption was also affected by the matrix composition of the mine water samples, apparently due to competitive sorption from other ions in the mine water. Use of site Mn for water treatment provides a more sustainable treatment approach; however, additional knowledge is required to understand the effects of site-specific complexities.