人工合成图水羟砷铁矾的矿物学研究

图水羟砷铁矾是目前发现的存在于酸矿废水中的唯一的亚砷硫酸盐含铁矿物,其化学式为Fe6(AsO3)4(SO4)(OH)4.4 H2O。图水羟砷铁矾对研究酸矿废水中砷地球化学以及冶金含砷废水处理都具有重要意义。本文通过恒温水浴反应器合成该矿物,首次采用红外光谱和拉曼光谱对其表征,结果表明:位于770 cm-1处的红外特征峰来自矿物中As—O伸缩振动;位于609、663、512、455和365 cm-1处的拉曼特征峰分别来自矿物中As—OH不对称伸缩振动、As—OH伸缩振动(υ3)、AsO33-不对称弯曲振动(υ4)(512和455 cm-1)和O—As—O弯曲振动;光电子能谱结果表明矿物中As为+3价,不存在更高氧化态。低pH值和高硫酸根有利于矿物获得较好晶形;矿物在pH>3出现不谐溶解,首次测定矿物溶度积常数(Ksp)为107.7,标准吉布斯反应自由能(ΔG0f)为-3 605 kJ/mol。

Acid mine drainage activation mechanism on lime-depressed pyrite flotation from copper sulfide ore

The lime-depressed pyrite from Cu differential flotation tailings with acid mine drainage(AMD)as a natural activator was recovered.The effect of AMD on lime-depressed pyrite flotation was investigated by a series of laboratory flotation tests and surface analytical techniques.Flotation test results indicated that AMD could effectively activate the pyrite flotation with a sodium butyl xanthate(SBX)collector,and a high-quality sulfur concentrate was obtained.Pulp ion concentration analysis results indicated that AMD facilitated desorption of Ca^(2+)and adsorption of Cu^(2+)on the depressed-pyrite surface.Adsorption measurements and contact angle analysis results confirmed that adding AMD improved the adsorption amount of SBX collector on the pyrite surface and increased the contact angle by 31°.Results of Raman spectroscopy and X-ray photoelectron spectroscopy analysis indicated that AMD treatment promoted the formation of hydrophobic species(S^(0) hydrophobic entity and copper sulfides)and the removal of hydrophilic calcium and iron species on the pyrite surface,which reinforced the adsorption of collector.The findings of the present research provide important theoretical basis and technical support for a cleaner production of copper sulfide ores.

Archaeal and bacterial communities in acid mine drainage from metal-rich abandoned tailing ponds, Tongling, China

To expand knowledge on microbial communities of various metal-rich levels of mine drainage environments in Anhui province, China, the archaeal and bacterial diversities were examined using a PCR-based cloning approach. Eight acid mine water samples were collected from five areas in Tongling. Phylogenetic analyses revealed that bacteria mainly fell into ten divisions, which were Betaproteobacteria, Gammaproteobacteria, Alphaproteobacteria, Deinococcus-Thermus, Nitrospira, Firmicutes, Actinobacteria, Deltaproteobacteria, Bacteroidetes, Chloroflexi. Archaea fell into three phylogenetic divisions, Thermoplasma, Ferroplasma and Thermogymnomonas. The unweighted pair group method with arithmetic mean（UPGMA） cluster analysis based on the microbial communities’ compositions revealed that five samples shared similarity with the dominance of Meiothermus and Thermomonas. Two samples had the preponderant existence of Acidithiobacillus and Leptospirillum. The remaining sample owned higher microbial communities’ diversity with the Shannon-Weaver H up to 2.91. Canonical correlation analysis（CCA） suggested that microbial community structures had great association with p H and the concentration of Hg2＋, Pb2＋, Fe3＋, Cl-, SO2- 4in water.

Heavy Metals in a Sulfldic Minespoil: Fractions and Column Leaching

Fractions of various heavy metals in a sulfidic minespoil were investigated. Column leaching experimentwas also conducted to simulate 'acid mine drainage' (AMD) from the minespoil. The results show thatleaching of heavy metals from the minespoil was extremely significant during the initial water flushing.The amounts of heavy metals leached out dramatically reduced after leaching twice. It is worthwhile tonote that in this study, Zn, Mn, Fe, As and Ni in the first leachate exceeded the total amount of eachcorresponding water-extractable (1:5, soil:water) metal contained in the minespoil sample. This appears tosuggest that 1:5 water extraction did not allow accurate estimation of water-leachable concentrations of theabove heavy metals. This work has implications for the management of sulfidic minespoils. Acid drainageof great environmental concerns is likely to occur only during heavy rainfall events after substantial solubleand readily exchangeable acid and metals are accumulated in the minespoils. The slow-reacting fractionsother than water-soluble and readily exchangeable fractions may pose little environmental hazards. This isparticularly true for Pb, As and Ni.

Sulfide mineral bioleaching:Understanding of microbe-chemistry assisted hydrometallurgy technology and acid mine drainage environment protection

Bioleaching is regarded as an essential technology to treat low grade minerals,with the distinctive superiorities of lower-cost and environment-friendly compared with traditional pyrometallurgy method.However,the bioleaching efficiency is unsatisfactory owing to the passivation film formed on the minerals surface.It is of particular interest to know the dissolution and passivation mechanism of sulfide minerals in the presence of microorganism.Although bioleaching can be useful in extracting metals,it is a double-edged sword.Metallurgical activities have caused serious environmental problems such as acid mine drainage(AMD).The understanding of some common sulfide minerals bioleaching processes and protection of AMD environment is reviewed in this article.

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.

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 add 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 miU 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.

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.

Bioleaching of chalcocite by mixed microorganisms subjected to mutation

Mixed microorganisms with elevated activity of chalcocite-leaching were screened by mutation methods. The original microorganisms collected from acid mine drainage of different sites were mixed and then treated with mutagens NO2^- , diethyl sulfate （DES）, UV and their combinations, respectively. Five groups of mixed microorganisms with much stronger ore-leaching ability were obtained by screening on the leaching media. Among them, group E of mixed microorganisms （treated with 1% DES for 60 min） with the best perfonnance on chalcocite-leaching, increases the content of Cu^2＋ by 101.4% in 20 d of leaching compared with the control culture. In addition, group E is more tolerant to Cu^2＋ in media than the control without mutation treatment. Analysis for the diversity of microbial clones indicates that half of operational taxonomic units （OTUs） in group E are Acidithiobacillus ferrooxidans. These observations suggest that group E might have potentials for industrial application.

Effect of loess for preventing contamination of acid mine drainage from coal waste

Acid mine drainage （AMD） that releases highly acidic, sulfate and metals-rich drainage is a serious environmental problem in coal mining areas in China. In order to study the effect of using loess for preventing AMD and controlling heavy metals contamination from coal waste, the column leaching tests were conducted. The results come from experiment data analyses show that the loess can effectively immobilize cadmium, copper, iron, lead and zinc in AMD from coal waste, increase pH value, and decrease Eh, EC, and 8024- concentrations of AMD from coal waste. The oxidation of sulfide in coal waste is prevented by addition of the loess, which favors the generation and adsorption of the alkalinity, the decrease of the population of Thiobacillusferrooxidans, the heavy metals immobilization by precipitation of sulfide and carbonate through biological sul- fate reduction inside the column, and the halt of the oxidation process of sulfide through iron coating on the surface of sulfide in coal waste. The loess can effectively prevent AMD and heavy metals contamination from coal waste in in-situ treatment systems.

Modeling of titration experiments by a reactive transport model

Acid mine drainage（AMD） is commonly treated by neutralization with alkaline substances.This treatment is supported by titration experiments that illustrate the buffering mechanisms and estimate the base neutralization capacity（BNC） of the AMD.Detailed explanation of titration curves requires modeling with a hydro-chemical model.In this study the titration curves of water samples from the drainage of the As Pontes mine and the corresponding dumps have been investigated and six buffers are selerted by analyzing those curves.Titration curves have been simulated by a reactive transport model to discover the detailed buffering mechanisms.These simulations show seven regions involving different buffering mechanism.The BNC is primarily from buffers of dissolved Fe,Al and hydrogen sulfate.The BNC can be approximated by：BNC = 3（C_（Fe） ＋ C_（Al）） ＋ 0.05C_（sulfate）,where the units are mol/L.The BNC of the sample from the mine is 9.25×10^（-3） mol/L and that of the dumps sample is 1.28×10^（-2） mol/L

Dye removal using some surface modified silicate minerals

The objective of this work is to study the efficiency of some surface modified phyllosilicate minerals （bentonite and glauconite） in the removal of dyes from textile waste water. It is found that complete dye removal was achieved by using 10-25g modified glauconite from solutions having a dye concentration of 10-50 mg/L. Adsorption data were modeled using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. Adsorption capacities and optimum adsorption isotherms were predicted by linear regression method. The analysis of experimental isotherms showed that Langmuir isotherm reasonably fit the experimental data in the studied concentration range for the adsorption of dye onto glauconite mineral surface where Freundlich isotherm fit the experimental data for the adsorption of dve onto bentonite mineral surface.

Biochar:An Emerging Panacea for Remediation of Soil Contaminants from Mining,Industry and Sewage Wastes

Mine tailings, waste rock piles, acid mine drainage, industrial wastewater, and sewage sludge have contaminated a vast area of cultivable and fallow lands, with a consequence of deterioration of soil and water quality and watercourses due to the erosion of contaminated soils for absence of vegetative cover. High concentrations of toxic elements, organic contaminants, acidic soils, and harsh climatic conditions have made it difficult to re-establish vegetation and produce crops there. Recently, a significant body of work has focussed on the suitability and potentiality of biochar as a soil remediation tool that increases seed emergence, soil and crop productivity, above ground biomass, and vegetation cover on mine tailings, waste rock piles, and industrial and sewage waste- contaminated soils by increasing soil nutrients and water-holding capacity, amelioration of soil acidity, and stimulation of microbial diversity and functions. This review addresses： i） the functional properties of biochar, and microbial cycling of nutrients in soil; ii） bioremediation, especially phytoremediation of mine railings, industrial waste, sewage sludge, and contaminated soil using biochar; iii） impact of biochar on reduction of acid production, acid mine drainage treatment, and geochemical dynamics in mine railings; and iv） treatment of metal and organic contaminants in soils using biochar, and restoration of degraded land.