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.

     

Removal of Dissolved Arsenic by Pyrite Ash Waste

Pyrite ash (PA), a waste produced during the roasting of pyrite ores to produce sulfuric acid, was studied as a potential adsorbent for removing arsenic (As) from groundwater. The collected pyrite ash waste samples contained >86 % iron (as Fe₂O₃). The results indicate that adsorption of As by PA was only slightly affected by initial pH at pH ≤ 9. Arsenate removal efficiency increased with the amount of adsorbent added over the range of 0.1–50 g/L. The As(V) removal increased with time, and 79 % removal was achieved within 1 h. Moreover, there was no significant change in As concentrations after 24 h. The adsorption process was best described by a second-order kinetic model. The adsorption of As(V) onto the PA was found to have followed the Langmuir isotherm. In batch studies, the maximum As(V) removal efficiency was 97 % at an adsorbent dose of 10 g/L, with an initial As(V) concentration of 300 µg/L. Thus, the PA was shown to be a suitable sorbent, reducing As from an initial level of 600 to <10 μg/L As(V), i.e., below the WHO limit for drinking water.     

The Distribution of Antimony and Arsenic in Waters of the Dúbrava Abandoned Mine Site, Slovak Republic

The abandoned Dúbrava Mine, situated in the northern part of the Nízke Tatry Mts in the middle of Slovakia, was the most significant producer of antimony (Sb) in the former Czechoslovakia. Mine drainage from adits (containing up to 9,300 μg/L of Sb), mine waste dumps, and the leachate from mine tailings contribute Sb and arsenic (As) into nearby Palud?anka Creek and groundwater. Some drinking water resources have been closed due to excessive Sb concentrations; the concentration of Sb in one household well (126 μg/L) far exceeds the Sb drinking water limit of 5 μg/L. Although Sb is attenuated by dilution and adsorption on ferric iron in stream sediment in the Palud?anka Creek, Sb concentrations increase downstream of the mine tailings and then remain almost constant, leading to concentrations of 128 μg/L at the northern boundary of the study area. The dissolved As concentrations in the mine drainage are much lower than Sb, ranging from 4 to 62 μg/L. Flow and transport modeling confirmed the observed contamination pattern and the major role of the mine adits. Results of this study indicate serious Sb contamination, which could be mitigated by treatment of the adit discharges.     

The Potential Use of Phosphatic Limestone Wastes in the Passive Treatment of AMD: A Laboratory Study

In Morocco, there are many sedimentary phosphate mines that produce large quantities of phosphatic limestone wastes (PLW) that contain calcite (46 wt%) and dolomite (16 wt%). These mines are located near contaminated sites, such as the abandoned Kettara pyrrhotite mine. The surface drainage water at the Kettara mine site has a pH of 2.9–4.2 and elevated concentrations of SO₄ (from 47 to 5,000 mg/L) and Fe (from 1 to 1,200 mg/L). The efficiency of PLW was assessed in the laboratory as an alternative alkaline material for passive acidic mine drainage (AMD) treatment. A series of experiments were carried out using a synthetic AMD (pH 3) containing Fe (500 mg/L), SO₄ (3.4 g/L), Ca (220 mg/L), Al (160 mg/L), Mn (20 mg/L), Zn (15 mg/L), Cu (23 mg/L), and trace amounts of Co, Cr, and Ni. Experiments were done in both anoxic and oxic conditions, in batch and column tests, with hydraulic retention times of 24 and 15 h, respectively. The PLW efficiently increased the alkalinity and pH, inducing precipitation of most metals. The neutralizing capacity of PLW prepared at different particle sizes (0.8 mm–0.5 cm, 0.5–1, 1–2, and 2–3 cm) was found to be similar in batch tests. The initial AMD value increased from 3 to 5–6.5 during the batch tests and 6.5–8 in the columns. In batch tests under anoxic and oxic conditions, there was a significant decrease in concentrations of Fe (500–120 mg/L), Al (160–1.7 mg/L), and Cu (23–0.002 mg/L). In the column tests, Al and Cu decreased (177–2.5 and 26–0.002 mg/L, respectively), while Fe decreased less significantly (618–300 mg/L). The availability and low cost of the PLW make its use in passive AMD treatment potentially feasible.     

Тhe Еffectiveness of Metal and Metalloid Sorption from Mining Influenced Waters by Natural and Modified Peat

This study investigated the sorption behaviour of natural (N peat) and HCl-acid-modified peat (HCl peat) for contaminants in water collected at a mine site in northern Finland. Batch sorption experiments were conducted at room temperature and at 5 °C. Characterization of the sorbents by FTIR and XPS revealed no substantial change in the peat’s functional groups due to the acid treatment. Generally, the N peat was a more efficient sorbent for the mine water, although the HCl peat exhibited better nickel uptake capacity (21 mg Ni/g) than the N peat (16 mg Ni/g) from synthetic water. This is attributed to the lower equilibrium pH in samples treated with the HCl peat as well as the water’s different chemical composition. At room temperature, the N peat removed As(V) (80%) and Ni (85%) at low dosage (1–2 g/L), whereas the HCl peat presented good removal of As(V) (80%) at low dosage (1 g/L) but did not achieve satisfactory removal of Ni, even at a higher dosage (4 g/L). The performance of both sorbents was significantly affected by contact time. Ni removal by N peat increased substantially with contact time whereas removals achieved by HCl peat increased slightly up to 60 min, but decreased significantly at 24 h. Unlike with HCl peat, the N peat was less efficient in the experiments conducted at 5 °C. Overall, for both sorbents, As(V) and Ni were the most efficiently removed contaminants from the mine water. HCl peat had slightly better settling properties, however, both products settled poorly, thus rendering the studied mixing and settling system unsuitable for the proposed application. Nevertheless, both peat products, and especially the N peat, exhibited high contaminant removal potential and could represent a cost-effective and sustainable option for mine water treatment.     

Fenton试剂氧化—絮凝法去除水中As(Ⅲ)

随着地下水砷污染问题的加重,砷污染已成为世界普遍关注的问题。为寻求经济合理的除砷技术,采用Fenton试剂氧化—絮凝法进行了水中As(Ⅲ))的去除试验。当废水初始As(Ⅲ)浓度为0.5 mg/L时,试验确定的最佳除砷条件为,调节废水初始pH=3.0、H_2O_2用量10 mg/L、Fe~(2+)与H_2O_2的摩尔比0.2、反应时间10 min,此时As(Ⅲ)去除率为95.17%。采用此最佳条件对赣州某实际废水进行除砷试验表明,As(Ⅲ))去除率可达94.71%,反应后水中As(Ⅲ))浓度为0.004 2 mg/L,低于《GB5749—2006生活饮用水卫生标准》中0.01 mg/L的标准。Fenton氧化—絮凝法除砷是利用Fenton反应产生的中间产物(包括H_2O_2、·OH、O_2·、·HO_2等)将As(Ⅲ)氧化与铁盐絮凝结合起来的一种方法。     

微电解-生物法处理酸性重金属矿山地下水

为使莱芜某矿的酸性地下水得到利用，对该地下水中所含锌、铜、铅3种重金属离子的去除方法进行了试验研究。试验将原水首先通过铸铁屑和活性炭组成的微电解反应器预处理30min，然后进入后续的厌氧生物反应器进行生化处理4h。结果表明，当厌氧生物反应器内搅拌机的转速为40r／min时，出水的pH为7左右，出水中Zn^2＋、Cu^2＋和Ph^2＋的浓度分别为0．20mg／L、0．08mg／L和0．06mg／L，微电解一生物法组合工艺对3种金属离子的去除率均大于99％，处理后的水质指标达到了矿山选矿工艺用水的要求，且不存在二次污染问题。     

涂铁改性火山岩去除矿井水中铁锰离子试验

利用涂铁改性火山岩滤料对矿井水进行了除铁除锰的试验研究.结果表明,改性火山岩滤料对铁锰离子的吸附都遵循Freundlich等温吸附模型.动态对比试验中,改性火山岩对矿井水中铁离子的去除率达80%～99%,与锰砂效果接近,但略低于火山岩;对锰离子的去除,改性火山岩效果最佳,在过滤前6 h,锰去除率接近100%,6 h后锰去除率随过滤时间呈线性降低.结合扫描电镜和能谱,分析了滤料的表面形貌和化学组成,并对改性火山岩滤料除铁除锰机理进行了分析.     

Adsorptive Performance of Surface-Modified Montmorillonite in Vanadium Removal from Mine Water

Montmorillonite modified with hexadecyltrimethylammonium bromide was used to remove vanadium (V) from synthetic and real mine water. Fourier transform infrared, X-ray diffraction, and scanning electron microscopy were used to characterise the adsorbent before and after adsorption, while the amount of V adsorbed was determined by ICP-OES. Batch adsorption was evaluated for dissolved V concentrations of 50–320 mg/L and V tailings seepage water from a South African mine. Adsorption capacity was affected by solution pH, temperature, sorbent mass, and the initial concentration. Electrical conductivity of the mine water before and after adsorption was measured to estimate the total dissolved solids. Equilibrium isotherm results revealed that V sorption follows the Freundlich isotherm, indicating that the sorbent surface was heterogeneous. A pseudo-second order kinetic model gave the best fit to the kinetic experimental data. The results of this study allow us to predict uptake efficiency of South African montmorillonite for V removal from mine water. However, the best adsorbent for the uptake of V or other contaminants will depend on the effluent to be treated.     

Antimony Mobilization through Two Contrasting Gold Ore Processing Systems,New Zealand

Antimony, a toxic metalloid similar to arsenic, is present at variable levels in most gold-bearing rocks. Antimony is soluble in the surface environment, so antimony (Sb) mobilization in mine waters is an environmental issue around gold mines. The Reefton gold mine was originally developed in gold-bearing quartz veins; Sb concentrations were low (<100 mg/kg) compared to arsenic (As) concentrations (>1,000 mg/kg), and the mine waters had low dissolved Sb (<0.1 mg/L). A second stage of gold mineralization at Reefton involved brecciation and cataclasis of quartz veins and wall rocks, with addition of stibnite (Sb₂S₃). Processing of this ore has resulted in higher dissolved Sb in mine waters (0.1–1 mg/L), even after water treatment that removes most dissolved As (to 0.01 mg/L) by adsorption to suspended iron oxyhydroxide. Competition between As and Sb for adsorption sites on iron oxyhydroxide particles may have resulted in partial exclusion of the more weakly adsorbed Sb. The high rainfall (2,000 mm/year) at Reefton ensures adequate dilution of mine waters after discharge. The Macraes gold mine has no stibnite, and most Sb is in solid solution in the abundant arsenopyrite (Sb up to 2,000 mg/kg). Pit waters have both Sb and As dissolved up to 0.1 mg/L, partly because of evaporative concentration in a low-rainfall environment. Macraes tailings waters have high As (up to 3 mg/L) but negligible Sb (<0.001 mg/L). Reefton mine gold-bearing concentrate, containing stibnite, is transported 700 km to be processed by autoclave oxidation and cyanidation at the Macraes mine. This introduction of additional Sb to the Macraes site substantially increases the Sb content of the process stream periodically. Tailings from this process have up to 3 wt% Sb, dispersed through As-rich iron oxyhydroxides that are formed in the autoclave. The Sb-rich tailings are strongly diluted (approximately 100:1) by the Macraes tailings, and adsorption of Sb to iron oxyhydroxides in the tailings piles ensures that there has been no increase in the Sb content of the tailings water since the Reefton concentrate has been added at Macraes.     

Treatment of Acidic and Neutral Metal-Laden Mine Waters with Bone Meal Filters

Bone meal was used to treat two different mine waters: acidic (pH 4.5) mine water containing high concentrations of Fe and Al and neutral/slightly alkaline (pH 7) mine water. Original primary contaminants in both waters were Pb and Zn. The contaminants were dissolved in the acidic mine water and mostly suspended in the neutral mine water. Flow through the filter treating the acidic mine water was relatively low (0.1 L/min), but increased towards the end of the test period. Removal of Pb and Cu was very good in the acidic mine water (around 80 %); removal of Zn was slightly less (60 %) due to the final pH (≈6–6.5). Flow through the filter treating the neutral mine water was initially significantly higher (5 L/min) and the removal of Pb and Zn was less compared to the acidic mine water (50 % for Pb and 35 % for Zn). The major reason for the difference in metal removal in the two mine waters was the difference in Fe and Al sorption sites, flow rate, and pH; in order for the bone meal to dissolve and form metal phosphate, the pH has to be <7.     

Performance of Semi-passive Systems for the Biological Treatment of High-As Acid Mine Drainage: Results from a Year of Monitoring at the Carnoulès Mine (Southern France)

Two semi-passive treatment systems for iron (Fe) and arsenic (As) removal in AMD were installed and monitored in-situ for more than a year. These technologies were designed to treat the As-enriched AMD (≈ 1 g/L Fe(II) and 100 mg/L As(III)) of the ancient Carnoulès mine. The treatment was based on biological Fe and As oxidation by indigenous bacteria, and subsequent immobilization of As by ferric hydroxysulfates. Forced aeration and wood/pozzolana or plastic support were used for biofilm attachment. The system performance ranged from 86 to 98% for Fe oxidation, 30 to 60% for Fe removal, and 50 to 80% for As removal at a hydraulic retention time of 9 h. No significant difference were measured between the two biofilm supports. The wood/pozzolana support had a shorter delay for performance recovery after interruptions. Iron oxidation rates were similar to those obtained in the Carnoulès AMD stream and laboratory bioreactor, while As oxidation seemed to be enhanced. The sludge accumulated between 39 and 91 mg/g of As, mainly in the As(V) oxidation state; jarosite and amorphous ferric hydroxysulfate phases were the main Fe and As scavengers. Challenging environmental conditions during the long monitoring period confirm the robustness of the treatment units. The data will be useful in designing future full-scale treatment systems adapted to As-rich AMD.

     

Effect of Temperature on Arsenic Treatment and Mobility in Mine Influenced Water

Mine Water and the Environment - Natural and artificial sorption of arsenic on iron hydroxides is one of the most important reactions controlling arsenic mobility in mine water and other water...     

Antimony Mobilisation and Attenuation During Ore Processing at Orogenic Gold Mines,Southern New Zealand

Mine waters at the Reefton orogenic gold mine (active from 2007 to 2016) in southern New Zealand contained dissolved arsenic (As) and antimony (Sb) up to 5 mg/L during production of a sulfide concentrate that included arsenopyrite (FeAsS) and stibnite (Sb₂S₃). Ferric oxyhydroxide adsorption extracted As down to?<?0.1 mg/L but dissolved Sb remained elevated due to adsorption competition with As. The Reefton sulfide concentrate was transported 700 km to the Macraes orogenic gold mine (active from 1990) for processing through a pressure oxidation autoclave at 225 °C. The Macraes ore has low Sb contents, so the temporary introduction of a Sb-rich component produced a short-term Sb signal in the autoclave system and tailings waters. Oxidation of stibnite occurred rapidly in the autoclave, in parallel with the As in the arsenopyrite, producing ferric antimonate (tentatively identified as As-bearing tripuhyite) and ferric arsenate (FeAsO₄). Dissolved Sb in the Macraes tailings waters remained?<?0.1 mg/L throughout the period of Reefton concentrate addition. The formation of tripuhyite in the high-temperature autoclave stabilised Sb in the Macraes tailings, so that dissolved Sb?<?As, in contrast to the low-temperature processes at Reefton where dissolved Sb?>?As.

     

Removal of Metals and Acidity from Acid Mine Drainage Using Municipal Wastewater and Activated Sludge

Co-treatment of acid mine drainage (AMD) and municipal wastewater (MWW) using the activated sludge process is an innovative approach to AMD remediation that utilizes the alkalinity of MWW and the adsorptive properties of the wastewater particulates and activated sludge biomass to buffer acidity and remove metals. The capacity of these materials to treat AMD was investigated in batch mode metal removal tests using high-strength synthetic AMD (pH 2.8, Al 120–200 mg/L, Cu 18–30 mg/L, Fe 324–540 mg/L, Mn 18–30 mg/L, and Zn 36–60 mg/L). Using material from a range of MWW treatment plants, the performance of screened and settled MWW, activated sludges with mixed liquor suspended solids (MLSS) concentrations of 2.0 and 4.0 g/L, and return activated sludges with 6.0 and 7.4 g/L MLSS were compared. Similar trends were observed for the MWW and activated sludges, with removal efficiency generally decreasing in the order Al = Cu > Mn > Zn > Fe. Trends in Fe removal using settled MWW and activated sludges were highly variable, with removal <30 %. Using activated sludges, average removal efficiencies for Al, Cu, Mn, and Zn were 10–65 %, 20–60 %, 10–25 %, and 0–20 %, respectively. Sludge solids concentration was an important controlling factor in metal removal, with removal of Al, Cu, Mn, and Zn increasing significantly with solids concentration. Municipal wastewaters had greater neutralization capacities than activated sludges at high AMD loading ratios. Mixing AMD with screened MWW gave the highest removal efficiency for all metals, achieving average removal of 90–100 % for Al, Cu, and Fe, 65–100 % for Zn, and 60–75 % for Mn. These empirical findings are useful for developing process design parameters in co-treatment systems. Utilizing MWW and activated sludge to remediate AMD can potentially reduce materials and energy requirements and associated costs.     

石灰-铁盐法处理硫酸厂高砷废水的研究与应用

采用石灰-硫酸亚铁两段净化工艺,对以硫铁矿为原料的硫酸厂含砷废水进行处理研究。介绍了pH值、Fe/As比以及充气量等条件对砷的去除率的影响。结果表明:控制一段pH=10 5、Fe/As=1∶1,二段pH=8 5、Fe/As=10∶1,充气20min,沉淀1h,处理后外排废水中砷浓度小于0 5mg/L,达到国家排放标准。该方法处理费用低、工艺简单可行、操作方便,已在工业生产中应用。     

Field Trials of Low-cost Reactive Media for the Passive Treatment of Circum-neutral Metal Mine Drainage in Mid-Wales,UK

This paper addresses the ability of five low-cost reactive materials to remove Zn, Pb, and Cd from Fe-poor, circum-neutral pH metal mine water in Mid-Wales, UK. Compost, fly ash, waste shell material, iron ochre, and a mixture of blast furnace slag (BFS) and basic oxygen furnace slag (BOS) were used in a series of small-scale passive treatment cells to assess metal removal from mine drainage initially containing, on average, 23.5 mg/L Zn, 0.5 mg/L Pb, and 0.05 mg/L Cd. Trial treatment cells contained between 1.5 and 12 kg of reactive media, had a 15 min residence time, and treated a discharge of up to 1 L per minute. Fly ash from a peat-fired power station was found to be the most effective material for metal removal, with concentrations reduced to 0.02 mg/L Zn, 0.0069 mg/L Pb, and 0.0001 mg/L Cd from over 1,000 L of water (between 98.6 and 99.9% removal). The other materials initially achieved high levels of metal removal (between 75 and 99.9% Zn, Pb, and Cd removed); however, all of the materials were saturated with Zn after less than 200 L of water had been treated. Metal sorption ranged from 21.4 mg/g Zn for the peat fly ash to 0.0015 mg/g Cd for the compost and BOS/BFS slag. The results of the pilot-scale field trials can be scaled to demonstrate that a modest-sized fly ash treatment cell (2.6 × 2.6 × 1 m) in size would be sufficient to remove 90% of the total metal load (Pb, Zn, and Cd) from this 10 L/min mine water discharge for a 1 year period. Importantly this research demonstrates that passive treatment for metal mine drainage can comply with water quality directives but cannot be considered a ‘walk-away’ solution; it requires modest (potentially annual) maintenance.     

Adsorptive removal of arsenic from river waters using pisolite

This work presents the experimental results for arsenic removal from aqueous solutions using pisolite as a natural inorganic sorbent, a waste mineral product from Brazilian manganese ore mines. A pisolite sample was submitted to physical and chemical characterization; particle size analysis by screening, X-ray diffractometry, X-ray fluorescence, surface area determination by the Brunauer–Emmett–Teller (BET) method and atomic absorption spectrophotometry (AA) for the determination of the species concentration in the pisolite and in the aqueous solution samples from the experiments.Column and batch tests to contact pisolite and aqueous feed solutions were carried out for evaluation of the pisolite’s performance as a natural sorbent for arsenic removal. Experiments using activated pisolite and aqueous feed solutions prepared with Velhas River water were also performed. In the column system, 1.0 g of pisolite removed 1.41 mg of As (4.05% As extraction) from 630 ml of the aqueous feed solution and 1.0 g of activated pisolite extracted 3.51 mg of As (11.6% As extraction). Results for the batch tests with 100 ml of aqueous feed solution and 1.0 g of pisolite removed 1.29 mg of As (24.7% As extraction) and 1.0 g of activated pisolite extracted 3.17 mg (58.2% As extraction).     

高铁高锰矿井水水质特征及其净化机制

以鹤壁煤业集团九矿和寺湾矿矿井水为例,对高铁高锰矿井水的水质特征及其净化机制进行了研究.分析表明,矿井水具有溶解氧丰富、高矿化度、高浊度的特征,矿井水的处理不需专门设曝气装置;采用混凝沉淀和过滤模型试验,考察了铁、锰的去除效果及滤料、滤速等对过滤出水水质的影响,结果表明：混凝沉淀对铁的去除率在90％以上,对锰的去除率仅达20％左右;以KMnO₄溶液浸泡过的锰砂为滤料,过滤（滤速7~9 m/h）出水铁、锰含量均在0.1 mg/L以下,表明锰砂表面所形成的活性复合物质滤膜对锰的去除起到了关键性作用.     

Potential Release of Metals from Tailings and Soil at the Hamekasi Iron Mine,Hamadan, Iran

This study focused on acid neutralization reactions and the effects of water composition on the release and mobility of metals from mine tailings. The aims of this study were to: investigate leaching of metals from neutral mine tailings, determine the factors responsible for metal leaching, and investigate potential metal filtering by the soil. Tailings and soil samples were collected from an iron mine and analyzed. Equilibrium thermodynamic data and metal fractionation were then used to predict precipitation/dissolution of minerals and ion adsorption/desorption. Three column experiments were designed. The first column was filled with tailings, while the second column contained tailings above a layer of soil; both were leached with distilled water as rainfall. The third column was packed with soil and percolated with synthetic groundwater. The results indicated that iron (Fe) and zinc (Zn) mobility are mainly controlled by precipitation–dissolution mechanisms, while sorption onto oxides and carbonates limit the mobility of copper (Cu) and nickel (Ni). Cadmium (Cd) and manganese (Mn) mobility are affected by both mechanisms. Water discharging from column 3 (soil washed with groundwater) contained high concentrations of dissolved metals, indicating that water composition played an important role in metal mobility. Buffering minerals like carbonates and hornblende, chlorite, and albite decreased acid generation.