Removal of Copper from Acid Mine Drainage (AMD) or Acid Rock Drainage (ARD)

Acid mine drainage is wastewater from a mine having a low pH and an elevated level of dissolved heavy metals. These metals are harmful to aquatic, animal and human life. This paper looks at the removal of copper from acid mine drainage using ion exchange to less than 1 mg/l. A weak acidic cation resin was used. Spectrophotometric determination of copper with sodium diethyldithiocarbamate was used to determine the copper concentrations in the treated water. Using regression analysis, the experimental results gave a correlation coefficient of 0.977 and a coefficient of determination of 99.5%. Results indicated that the higher the flows rate the shorter the period after which the copper concentration in the treated water reaches 1 mg/l. At pH 3.85 and 5.09, the resin performed better and at pH above 6.62 and between pH 3.0 and below the resin’s does not perform well. The higher the resin height the greater is the resin exchange capacity and the longer it takes for the copper concentration to reach 1 mg/l in the treated water. The higher the wastewater copper concentration the shorter the time it takes the resin to reach 1 mg/l. The results for this experiment indicated that acid mine drainage can be treated well by ion exchange resins, but it is also very important to establish suitable operating conditions.

Coal-derived humic acid for application in acid mine drainage(AMD)water treatment and electrochemical devices

In this research work,isolation of humic acid from coal of Northeastern region of India is reported.The study is also targeted for application of the coal-derived humic acid in acid mine drainage(AMD)water treatment and electrochemical devices.All the obtained results are compared with the standard humic acid and examined the formation of humic acid from the coal.The isolated coal-derived humic acid is found to be high degree of humifications and relatively stable up to about 200℃.The FTIR study indicates the formation of metal-humic acid complexes.On treatment with acidic water(AMD),the coal-derived humic acid was found to have the ability to remove toxic metal such as(in order)Pb>Cu>Zn>Cd.In addition,the preliminary electrochemical properties of the isolated humic acid are also discussed in the paper.The specific capacitance of the isolated coal-derived humic acid via cyclic voltammetry and charge-discharge analysis is found to be 7 mF/g at scan rate 10 mV/s and 22 mF/g within the potential window 0.4 V,respectively.The charge-discharge cycles are stable for more than 1000 cycles within the potential window 0.4 V.This study will create a new pathway for the further research in this field.

The Key Factor of Acid Mine Drainage (AMD) in the History of the Contribution of Mining Industry to the Prosperity of the United States and South Africa: A Review

Mining industry has significantly contributed to the prosperity of the nation with economic growth, whereas mining operation has caused Acid Mine Drainage (AMD) with the abandonment of mines. As some researchers suggest, the history of AMD is, generally, affected by the change in not only mining industry but also in social and economic conditions. Thus, historical analysis is an effective way to find the key factors of AMD. In this study, in order to find the key factors of AMD, we examine the history of the United States (U.S.) and South Africa, where their economy had been developed owing to the large-scale mining, based on the findings in the previous studies. The results indicated that the abandoned mines due to the economic depression triggered AMD in the U.S. and South Africa. While the U.S. had progressively adopted anti-AMD methods in terms of prevention, prediction, and remediation (PPR) as a comprehensive approach, especially since the 1970s onwards because of the rise of environmental consciousness as well as strict regulations, South Africa is at the early stage of implementing the regulations following PPR. The public attention should be directed to environmental conservation in addition to the implementation of the regulations in South Africa. The improvement in socio-economic conditions is, additionally, necessary for the rise of environmental consciousness in South Africa in the light of the three pillars of sustainable development: social, economic, and environmental elements.

Inhibition of acid mine drainage and immobilization of heavy metals from copper flotation tailings using a marble cutting waste

Acid mine drainage （AMD） with high concentrations of sulfates and metals is generated by the oxidation of sulfide beating wastes. CaCO3-rich marble cutting waste is a residual material produced by the cutting and polishing of marble stone. In this study, the feasibility of using the marble cutting waste as an acid-neutralizing agent to inhibit AMD and immobilize heavy metals from copper flotation tailings （sul- fide-beating wastes） was investigated. Continuous-stirring shake-flask tests were conducted for 40 d, and the pH value, sulfate content, and dissolved metal content of the leachate were analyzed every 10 d to determine the effectiveness of the marble cutting waste as an acid neu- tralizer. For comparison, CaCO3 was also used as a neutralizing agent. The average pH value of the leachate was 2.1 at the beginning of the experiment （t = 0）. In the experiment employing the marble cutting waste, the pH value of the leachate changed from 6.5 to 7.8, and the sul- fate and iron concentrations decreased from 4558 to 838 mg/L and from 536 to 0.01 mg/L, respectively, after 40 d. The marble cutting waste also removed more than 80wt% of heavy metals （Cd, Cr, Cu, Ni, Pb, and Zn） from AMD generated by copper flotation tailings.

养殖废水对AMD重金属的处理效果及去除机制

文章研究牛粪发酵前后产物与酸性矿山废水(acid mine drainage,AMD)共处理过程及处理效果。结果表明,牛粪及发酵后产物(沼液)均对AMD具有不同程度的处理效果;处理前期,牛粪组R1和沼液组R2的pH值从3.07分别迅速升高到4.01和3.85,直至实验结束时pH值略有下降,分别达到3.91和3.47;酸度分别下降49.8%和44.83%。R1组Fe、Zn、Cu、Mn、Al等金属离子质量浓度分别下降72.34%、83.79%、96.48%、17.2%、46.89%;R2组Fe、Cu、Mn、Al质量浓度分别下降96.27%、61.40%、13.92%、48.19%。X射线衍射(X-ray diffraction,XRD)扫描结果表明2组实验对金属的去除主要以共沉淀为主,但在R1组中发现微生物可能对处理过程具有较大的推动作用。2组实验均对AMD具有较好修复效果,在利用养殖废水处理AMD具有很好的应用前景。

Acid Mine Drainage and Heavy Metal Pollution from Solid Waste in the Tongling Mines, China

Based on investigation of the characteristics of solid waste of two different mines, the Fenghuangshan copper mine and the Xinqiao pyrite mine in Tongling, Anhui province in central-east China, the possibility and the differences of acid mine drainage （AMD） of the railings and the waste rocks are discussed, and the modes of occurrence of heavy metal elements in the mine solid waste are also studied. The Fenghuangshan copper mine hardly produces AMD, whereas the Xinqiao pyrite mine does and there are also differences in the modes of occurrence of heavy metal elements in the railings. For the former, toxic heavy metals such as Cu, Pb, Zn, Cd, As and Hg exist mostly in the slag mode, as compared to the latter, where the deoxidization mode has a much higher content, indicating that large amounts minerals in the waste rocks have begun to oxidize at the earth surface. AMD is proved to promote the migration and spread of the heavy metals in mining waste rocks and lead to environmental pollution of the surroundings of the mine area.

Removal of Copper Ions from Acid Mine Drainage Wastewater Using Ion Exchange Technique: Factorial Design Analysis

A factorial experimental design method was used to examine the “Cu2+” removal from acid mine drainage wastewater by ion exchange technique. Ion Exchange technique is preferred because of reduced sludge generation compared to conventional treatment techniques and better decontamination efficiency from highly diluted solutions. Factorial design of experiments is employed to study the effect of four factors pH (3, 5, and 6), flow rate (5, 10, 15 L/hr), resin bed height (20, 40 and 60 cm) and initial concentration of the metal (100, 150 and 200 mgl-1) at three levels. The efficiency of metal removal was determined after 100 min of treatment. Main effects and interaction effects of the four factors were analyzed using statistical techniques. A regression model was recommended and it was found to fit the experimental data very well. The results were analyzed statistically using the Student’s t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage “Cu2+” removal. In this study , pH was thus found to be the most important variable.

Effect of hydraulic retention time and pH on oxidation of ferrous iron in simulated ferruginous acid mine drainage treatment with inoculation of iron-oxidizing bacteria

The effect of hydraulic retention time (HRT) and pH on the biooxidation of ferrous iron during simulated acid mine drainage (AMD) treatment was investigated.The simulated AMD was highly acidic (pH 2.5), rich in iron (about 1700 mg/L) and copper (about 200 mg/L), and contained high concentrations of sulfate (about 4700 mg/L).The biooxidation of ferrous iron was studied in a laboratory-scale upflow packed bed bioreactor (PBR).The HRT was shortened stepwise from 40 h to 20 h, 13 h, and 8 h under the acidic environment at a pH value of 2.2.Then, the influent pH value was changed from 2.2 to 1.2 at a constant suitable HRT.Physiochemical and microbial community structure analyses were performed on water samples and stuffing collected from the bioreactor under different conditions.The results indicate that the efficiency of ferrous iron oxidation gradually decreased with the decrease of HRT, and when the HRT exceeded 13 h, ferrous iron in AMD was almost completely oxidized.In addition, the best efficiency of ferrous iron oxidation was achieved at the influent pH value of 1.8.Microbial community structure analyses show that Leptospirillum is the predominant genus attached in the bioreactor, and low influent pH values are suitable for the growth of Leptospirillum.

Acidophilic bacterial community reflecting pollution level of sulphide mine impacted by acid mine drainage

To reveal the impact of mining on bacterial ecology around mining area,bacterial community and geochemical characteristics about Dabaoshan Mine(Guangdong Province,China)were studied.By amplified ribosomal DNA restriction analysis and phylogenetic analysis,it is found that mining pollution greatly impacts the bacterial ecology and makes the habitat type of polluted environments close to acid mine drainage(AMD)ecology.The polluted environment is acidified so greatly that neutrophil and alkaliphilic microbes are massively dead and decomposed.It provided organic matters that can make Acidiphilium sp.rapidly grow and become the most bacterial species in this niche.Furthermore,Acidithiobacillus ferrooxidans and Leptospirillum sp.are also present in this niche.The amount of Leptospirillum sp.is far more than that of Acidithiobacillus ferrooxidans,which indicates that the concentration of toxic ions is very high.The conclusions of biogeochemical analysis and microbiological monitor are identical. Moreover,because the growth of Acidithiobacillus ferrooxidans and Leptospirillum sp.depends on ferrous iron or inorganic redox sulfur compounds which can be supplied by continual AMD,their presence indicates that AMD still flows into the site.And the area is closer to the outfalls of AMD,their biomasses would be more.So the distinction of their biomasses among different areas can help us to find the effluent route of AMD.

Inhibition of hematite on acid mine drainage caused by chalcopyrite biodissolution

Even though biodissolution of chalcopyrite is considered to be one of the key contributors in the formation of acid mine drainage(AMD),there are few studies to control AMD by inhibiting chalcopyrite biodissolution.Therefore,a novel method of using hematite to inhibit chalcopyrite biodissolution was proposed and verified.The results indicated that chalcopyrite biodissolution could be significantly inhibited by hematite,which consequently decreased the formation of AMD.In the presence of hematite,the final biodissolution rate of chalcopyrite decreased from 57.9%to 44.4%at 20 day.This in turn suggested that the formation of AMD was effectively suppressed under such condition.According to the biodissolution results,mineral composition and morphology analyses,and electrochemical analysis,it was shown that hematite promoted the formation and accumulation of passivation substances(jarosite and Cu2-xS)on chalcopyrite surface,thus inhibiting the biodissolution of chalcopyrite and limiting the formation of AMD.

A novel acidophile community populating waste ore deposits at an acid mine drainage site

Waste ore samples （pH 3.0） were collected at an acid mine drainage （AMD） site in Anhui, China. The present acidophillc microbial community in the waste ore was studied with 16S rRNA gene clone library and denaturing gradient gel electrophoresis （DGGE）. Eighteen different clones were identified and affiliated withActinobacteria, low G ＋ C Gram-positives, Thermomicrobia, Acidobacteria, Proteobacteria, candidate division TM7, and Planctomycetes. Phylogenetic analysis of 16S rRNA gene sequences revealed a diversity of acidophiles in the samples that were mostly novel. It is unexpected that the moderately thermophilic acidophiles were abundant in the acidic ecosystem and may play a great role in the generation of AMD. The result of DGGE was consistent with that of clone library analysis. These findings help in the better understanding of the generation mechanism of AMD and in developing a more efficient method to control AMD.

Diversity of microbial community at acid mine drainages from Dachang metals-rich mine, China

Two acid mine drainage(AMD)samples TS and WK,which were from the Dachang metals-rich mine in Guangxi province,China,were studied using PCR-based cloning approach.A total of 44 operational taxonomic units(OTUs)were obtained from the two AMD samples.However,only three OTUs(GXDC-9,GXDC-19 and GXDC-50)detected in sample TS can also be observed in sample WK.Phylogenetic analysis revealed that the bacteria in the two samples fell into four putative divisions,which were Nitrospira,Alphaproteobacteria,Gamaproteobacteria,and Acidobacteria.Organisms of genuses Acidithiobacillus and Leptospirillum,which were in gamaproteobacteria class and Nitrospira family,were dominant in two samples,respectively.In sample TS,which was characterized by low pH,high sulfate,high iron,and high arsenide,two species(Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans)constituted 98.22% of the entire microbial community.Compared with sample TS,the microbial community in sample WK was more diversified according to the observation.Interestedly,the Legionella species,which was rarely observed in the low-pH environment,was detected in sample WK.This work helps us to further understand the diversity of microbial community living in extreme acid mine drainages with unique geochemistry and the tolerance capability of acidophiles to heavy metal.

An effective way to treat the iron-rich acid mine drainage from coal mining in Guizhou’s mountainous areas

Acid Mine Drainage(AMD)from coal mining is a serious environmental issue which affects water quality,ecology,and the overall landscape of the basin.A large number of coal mine tailings in the mountainous regions of Guizhou Province,China were unattended and iron-rich AMD was directly discharged to the rivers.This discharge leaves the river―yellow‖and heavily polluted.This study tries to find an efficient and economical method for treating iron-rich AMD.We sampled AMD water in two sites:Yangliujie town of Duyun city(hereafter,called Yangliujie),and Xinglong Coal Mine,Duliu town of Guiding county(hereafter,called Xinglong).We performed iron removal laboratory experiment with Cement-Bentonite Agent(CBA,80%cement and 20%bentonite)in 500 mL AMD water from Yangliujie,scale-up experiment in 15 L AMD water from both Yangliujie and Xinglong,and engineering application in Xinglong respectively.Laboratory experiment results showed the iron removal rate can reach 99.8%and the removal rate depends on the CBA dosage and the treatment time.In the scale-up experiment,we found that Fe concentration could be reduced from 587.0 to 0.2 mg/L when adding 20 g/L CBA to the AMD water and aerating for 3 hours.As sampled water in Xinglong has a very high Fe concentration(Fe 1019.8 mg/L)and the concentration varies with seasons,it is not economical to add the CBA directly to the AMD water.Considering the abundant and cheap limestone resources in Guizhou,we used a twostep treatment method,first we added CaCO3 to raise the pH,and then we took the supernatant liquor and added CBA to the liquor.It was shown that 15 g/L of CBA was a good dosage for iron removal with Fe concentration being reduced from 1019.8 to 0.3 mg/L when CaCO3 was used to raise the pH.The best treatment realized over 99.9%iron removal,99.2%NH3-N removal,98.9%CODMn removal,and heavy metals in the treated water were reduced to under the limit stipulated in the―Environmental Quality Standards of Surface Water in China‖.Thus in the engineering application,we used this two-step treatment method.After the treatment,the pH of the iron-rich AMD(pH 2.86,Fe 2624.6 mg/L)increased to 8.53,the concentration of Fe was reduced to 59.5 mg/L,NH3-N decreased from 16.15 to less than 0.05 mg/L,CODMn decreased from 323.33 to 24.57 mg/L,heavy metals except Fe and Mn were reduced to under the limit of surface water.In conclusion,the use of CBA can effectively remove Fe and other heavy metals from the iron-rich AMD and adjust the pH value to the range of a natural water body.

The Dynamic Experiment on Treating Acid Mine Drainage with Iron Scrap and Sulfate Reducing Bacteria Using Biomass Materials as Carbon Source

The study is aimed at the problem of high content of Cr^(6+),Cr^(3+)and SO_(4)^(2-)is high and low pH value in acid mine drainage(AMD).Moreover,treatment of AMD by sulfate reducing bacteria(SRB)requires the addition of carbon source,while the treating effectiveness is not good enough on its own.The sugarcane slag,the corn cob and the sunflower straw were selected as the SRB carbon source cooperating with iron scrap to construct the dynamic columns 1,2 and 3.The mechanism of removing Cr^(6+),Cr^(3+),SO_(4)^(2-)and H+and the regularity of sustained release of carbon source and TFe release was studied in AMD.The removal efficiency of heavy metal ions,the ability of sustained release of carbon source,and the ability of adjusting acid by the three dynamic columns were compared.The result shows that the average removal rates of Cr^(6+),Cr^(3+)and SO_(4)^(2-)in effluent of dynamic column 1,filled by sugarcane slag,iron scrap and SRB,were 96.9%,67.1%and 54.3%.The average release of TFe and chemical oxygen demand(COD)were 4.4 and 287.3 mg/L.Its average pH was 6.98.Compared with the performance of dynamic columns 1,2 and 3,dynamic column 1 performed best in removing Cr^(6+),Cr^(3+)and SO_(4)^(2-)from AMD and controlling the release of COD and TFe,adjusting the pH of the solution.The study is of significance in treatment of AMD by taking for biomass materials as SRB carbon source in cooperation with iron scrap.

Study on the Treatment of Acid Mine Drainage Containing Fe^(2+) and Mn^(2+) Using Modified Spontaneous Combustion Gangue

The high concentrations of Fe^(2+) and Mn^(2+) in acid mine drainage make it difficult and expensive to treat.It is urgent that we find a cheap and efficient adsorption material to treat Fe^(2+) and Mn^(2+).As a solid waste in mining areas,coal gangue occupies a large area and pollutes the surrounding environment during the stacking process.Developing a method of resource utilization is thus a research hotspot.In this study,we modified spontaneous combustion gangue using NaOH,NaCl,and HCl by chemically modifying the minerals.We determined the optimal conditions for treating Fe^(2+) and Mn^(2+) in acid mine drainage with spontaneous combustion gangue and modified coal gangue using the single factor test method.Based on results of the static test,two dynamic test columns,column No.1(spontaneous combustion gangue)and column No.2(NaOH modified spontaneous combustion gangue),were constructed,and the repair effects of acid mine drainage were compared and analyzed using dynamic experiments.The results show that overall,NaOH modified spontaneous combustion gangue is the most efficient at removing the Fe^(2+) and Mn^(2+) in acid mine drainage.The optimal conditions for NaOH modification are an NaOH concentration of 3 mol/L,a liquid to solid ratio of 2 L/kg,and a modification time of 8 h.The overall efficiency of column No.2 at removing Fe^(2+) and Mn^(2+) from acid mine drainage is better than that of column No.1.Among them,the average removal efficiency of Fe^(2+)and Mn^(2+) from acid mine drainage in column No.2 were 97.73%and 44.82%,respectively.The above results show that NaOH modified spontaneous combustion gangue is a good adsorbent,which has application potential in wastewater remediation,as it can achieve the purpose of“treating dust with waste”.

Effects of acid drainage from abandoned coal mines on the microbial community of Shandi River sediment,Shanxi Province

The discharge of acid mine drainage from abandoned high sulfur(S)coal mines has caused serious pollution in the Shandi River,Yangquan,Shanxi Province.To determine the impact of long-term acid mine drainage on the microorganisms in the river,we collected river sediments from a polluted tributary(Group P)and the mainstream of Shandi River(Group R)to study the bacterial diversity and community composition.The results showed that the tributary was seriously polluted by acid drainage from abandoned coal mines,with the pH value of the sediment being<2.5,resulting in the low bacterial richness and diversity of the tributary samples.Acidophillic Fe-and S-metabolizing bacteria,such as Metallibacterium,Acidiphilium,and Acidithiobacillus,were the dominant genera in Group P samples,while the Group R was dominated by the neutral anaerobic iron-reducing bacteria Geothrix and Geobacter.Results of principal co-ordinates analysis(PCoA)revealed that the bacterial communities are significantly different between groups P and R,and the significant different species were mainly attributed to phylum Proteobacteria,Actinobacteria,and Acidobacteria.The distribution of the microbial community is mainly influenced by pH,and the Fe and Cd concentrations.Metallicactrium,the dominant genus,is negatively correlated with pH(R^(2)=-0.95)and positively correlated with Fe(R^(2)=0.99),while Geothrix and Geobacter,are mainly affected by the heavy metals.This study determined the impact of river pollution caused by abandoned coal mine drainage,especially on the microbial diversity and community composition within the river sediment.

A Study of Environmental Assessment of Acid Mine Drainage in Ngwenya, Swaziland

Acid mine drainage (AMD) is an industrial pollution of prime concern for the whole world. It is the driving force for an array of water pollutants especially heavy metals. Heavy metals (Cr, Mn, Fe, Ni, Co, Cu, Zn, Pb, Cd) were investigated in this study. Water and sediment samples were collected from the Ngwenya Iron Ore Mine Quarry Dam to investigate the occurrence of AMD phenomenon in the old mine. The main Fe compounds found in the Ngwenya Mine ore are haematite and pyrite. The Quarry Dam is located in one of the mine pits and it has neither visible inlet nor outlet. Physico-chemical parameters (pH, EC, ORP, T) were determined in the water by Electrochemical methods using the WTW 340i probes. Anions in the water were quantified by Ion Chromatography (IC) whereas heavy metals in water and sediments were quantified by Flame Atomic Absorption Spectrometry (FAAS). The BCR-Sequential Extraction procedure was used to speciate the heavy metals in the sediment samples. The mean pH of 4.34 in the Quarry Dam water is comparable to the pH of other AMD polluted water. The high mean EC of 4.522 mS/cm depicted that the water was laden with ions which are dissolved from the ore by the AMD. The sulfate ion, a well-known indicator for AMD pollution in water, is the second dominant anion where the order is NO3-> SO42-> Cl-. The heavy metal levels in water and sediments were in the order Co > Ni > Cr >Zn > Mn > Cu > Fe > Cd > Pb and Fe > Mn > Cr > Ni > Pb > Co > Cd > Cu > Zn respectively. The heavy metals are all bioavailable, hence they are potential health risks to both biota and residents in the vicinity of the mine. The pH of the water in the Quarry dam is comparable to those obtained for some other AMD polluted water. It is inferred that AMD is being produced in the old mine. It is recommended that an Environmental Impact Assessment of AMD must be carried out before the mine is re-opened.

Acid mine drainage and heavy metal contamination in groundwater of metal sulfide mine at arid territory (BS mine,Western Australia)

The issues of acid mine drainage(AMD) and heavy metals contamination in the metal sulfide mine in the arid district were explored,through studying the acidification and the heavy metals distribution and evolution of groundwater in the black swan(BS) nickel sulfide mine(Western Australia).The groundwater samples were collected from the drilling holes situated in the vicinity of tailings storage facility(TSF) and in the background of the mine(away from TSF),respectively,and the pH and electric conductivity (Ec) were measured in site and the metal contents were analysed by ICP-MS and ICP-AES,quarterly in one hydrological year.The results disclose that the TSF groundwater is remarkably acidified(pHmean≈5,pHmin=3),and the average contents of heavy metals (Co,Cu,Zn,Cd) and Al,Mn are of 1-2 orders of magnitude higher in TSF groundwater than in background groundwater.It may be due to the percolation of tailings waste water from mill process,which leads the tailings to oxidize and the deep groundwater to acidify and contaminate with heavy metals.Besides,the heavy metals concentration in groundwater may be controlled by pH mainly.

Erosion characteristic of slope sandstone soaking in acid mine drainage

Acid mine drainage(AMD) is one of the main reasons of slope instability in chemical mines with high sulfide. The pH values of the solution inside the mining pit decrease with the increasing of distance from ore body and vary from 1.2 to 4.6, according to the results of the water environmental investigation and the composition test of the slope sandstone in Xinqiao Pyrite Mine. Comparative experiments between original sandstone and AMD eroded sandstone samples show that after AMD erosion the uniaxial compressive strength and elastic modulus decrease by 30%-50% and 25%-45%, respectively, the cohesion and internal friction angle decrease obviously, and the Poisson ratio fluctuates between 0.20-0.29. The greater joints development, the higher residual stress after peak value, and the longer time to damage. Besides above, the reaction mechanism analysis of AMD eroded sandstone shows that the fillings in joints and fissures of sandstone are frequently decomposed and polyreacted, resulting in changes of interior molecule structure and framework composition, and decreases of cohesion and angle of internal friction between rock structure interfaces.