Coating development on mine waste rocks as a protective sink to attenuate the off-site migration of antimony in the environment.

This study explored the feasibility of depositing protective coatings with an Sb scavenger function on mine waste rocks derived from the exploitation of stibnite deposits. Encapsulation treatments were performed using ferrous sulfate as the coating precursor. Different Fe/Sb molar ratios (0.

Assessment of industrial by-products as amendments to stabilize antimony mine wastes.

The spread of antimony from mine wastes to the environment represents a matter of great concern due to its adverse effects on impacted ecosystems. There is an urgent need for developing and adopting sustainable and inexpensive measures to deal with this type of wastes. In this study the Sb leaching behavior of mine waste rocks and mine tailings derived from the exploitation of Sb ore deposits was characterized using standard batch leaching tests (TCLP and EN-12457-4) and column leaching essays.

Antimony distribution and mobility in different types of waste derived from the exploitation of stibnite ore deposits.

Wastes derived from the exploitation of stibnite ore deposits were studied to determine their mineralogical, chemical, and environmental characteristics and establish the Sb distribution and the current and long-term risks of Sb mobilization. Representative samples of mine waste rocks, mine tailings, and smelting waste were studied by X-ray powder diffraction, polarized light microscopy, electron microprobe analysis, and digestion, leaching, and extraction procedures. The main Sb-bearing minerals and phases identified in the smelting waste were natrojarosite, iron (oxyhydr)oxides, mixtures of iron and antimony (oxyhydr)oxides, and tripuhyite; those in the mine tailings and mine waste rocks were iron (oxyhydr)oxides and/or mixtures of iron and antimony (oxyhydr)oxides.

Application of different alkaline materials as polluted soil amendments: A comparative assessment of their impact on trace element mobility and microbial functions.

Treatment with chemical amendments is among the best techniques to remediate soils highly polluted with trace elements. The use of waste-derived products has several advantages in this regard, mainly in terms of reducing process costs and conserving natural resources. In this study, the performance of the synthetic zeolite NaP1 derived from coal combustion fly ash (SZ) and the by-product generated from the processing of aluminum salt slags (BP) was evaluated with this aim in comparison to calcite (CC).

Characterization of secondary products in arsenopyrite-bearing mine wastes: influence of cementation on arsenic attenuation.

The secondary products of an arsenopyrite-bearing mine waste dump were characterized in order to ascertain their mineralogical, chemical and environmental features and to appraise their role in the abatement of As in the environment. To this purpose, representative surface samples of weathered sulfides (including cemented phases) and hardpan samples were collected and studied by X-ray powder diffraction (XRD), polarized light microscopy, electron microprobe analysis (EMPA), micro-Raman spectroscopy and digestion, extraction and leaching methods. Scorodite, amorphous ferric arsenates (AFA), elemental sulfur, hydronium jarosite, goethite, hematite and hydrous ferric oxides were the secondary products identified in the mine wastes.

Arsenic distribution in a pasture area impacted by past mining activities.

Former mine exploitations entail a serious threat to surrounding ecosystems as after closure of mining activities their unmanaged wastes can be a continuous source of toxic trace elements. Quite often these mine sites are found within agricultural farming areas, involving serious hazards as regards product (feed/food) quality. In this work a grazing land impacted by the abandoned mine exploitation of an arsenical deposit was studied so as to evaluate the fate of arsenic (As) and other trace elements and the potential risks involved.

Trace element levels in an area impacted by old mining operations and their relationship with beehive products.

The environmental status of an area impacted by Roman mining activities was assessed in order to establish the current risks posed by such old mine emplacements. For this purpose, soil samples were collected throughout the mining area and analysed for their total, mobile and mobilizable trace element (As, Cd, Mo, Sb and Zn) contents. Additionally, beehive products (honey and pollen) were also sampled and evaluated for their use as environmental indicators of the area.

A comparative study on the influence of different organic amendments on trace element mobility and microbial functionality of a polluted mine soil.

A mine soil heavily polluted with zinc and cadmium was employed to evaluate the capacity of organic amendments of different origin to simultaneously reduce soil trace element mobility and enhance soil microbial functionality. With this aim, four organic products, namely olive processing solid waste (OPSW), municipal solid waste compost (MSWC), leonardite and peat, were applied individually at different doses (0, 1, 2 and 5%) to mine soil under controlled laboratory conditions. Extraction studies and analysis of soil microbiological parameters (basal soil respiration and dehydrogenase, β-glucosidase, urease, arylsulfatase and acid and alkaline phosphatase activities) were performed to assess the effect of such amendments on soil restoration.

Arsenic distribution in soils and rye plants of a cropland located in an abandoned mining area.

A mining impacted cropland was studied in order to assess its As pollution level and the derived environmental and health risks. Profile soil samples (0-50 cm) and rye plant samples were collected at different distances (0-150 m) from the near mine dump and analyzed for their As content and distribution. These cropland soils were sandy, acidic and poor in organic matter and Fe/Al oxides.

Evaluation of ferrihydrite as amendment to restore an arsenic-polluted mine soil.

The effectiveness of ferrihydrite as amendment to restore the soil habitat functioning of a soil polluted with As by mining activities was evaluated. Its influence on As mobility and phytoavailability was also assessed. Soil treated with increasing amendment doses (0, 1, 2, and 5 %) were analyzed for soil microbiological parameters such as basal soil respiration and dehydrogenase, β-glucosidase, urease, acid and alkaline phosphatase, and arylsulfatase activities.

Mobility and phytoavailability of antimony in an area impacted by a former stibnite mine exploitation.

A mining area affected by the abandoned mine exploitation of a stibnite deposit was studied to establish the current and eventual environmental risks and to propose possible remediation practices. Soil and plant samples were collected at different places in this area and analyzed for their Sb content and distribution. Critical soil total concentrations of Sb were found, with values ranging from 585 to 3184 mg kg(-1) dry weight in the uppermost soil layer, and decreasing progressively with soil depth.

Evaluation of different amendments to stabilize antimony in mining polluted soils.

Soil pollution with antimony is of increasing environmental concern worldwide. Measures for its control and to attenuate the risks posed to the ecosystem are required. In this study the application of several iron and aluminium oxides and oxyhydroxides as soil amendments was evaluated in order to assess their feasibility to stabilize Sb in mining polluted soils.

Antimony, arsenic and lead distribution in soils and plants of an agricultural area impacted by former mining activities.

An agricultural area impacted by the former exploitation of an arsenical lead-antimony deposit was studied in order to assess the current and eventual environmental and health impacts. Samples of soils and cultivated (wheat) and spontaneously growing plants were collected at different distances from the mine pits and analyzed for the toxic element content and distribution. The soil total concentrations of Sb, As and Pb found in the uppermost soil layer (14.

Fluoride accumulation by plants grown in acid soils amended with flue gas desulphurisation gypsum.

The application of flue gas desulphurisation (FGD) gypsum as an acid soil ameliorant was studied in order to establish the possible detrimental effects on plants and animals feeding on them caused by the high fluoride content in this by-product. A greenhouse experiment was conducted under controlled conditions to determine the F accumulation by two plant species (alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.

Arsenic distribution in soils and plants of an arsenic impacted former mining area.

A mining area affected by the abandoned exploitation of an arsenical tungsten deposit was studied in order to assess its arsenic pollution level and the feasibility of native plants for being used in phytoremediation approaches. Soil and plant samples were collected at different distances from the polluting sources and analysed for their As content and distribution. Critical soil total concentrations of As were found, with values in the range 70-5330 mg kg(-1) in the uppermost layer.

Study of arsenopyrite weathering products in mine wastes from abandoned tungsten and tin exploitations.

Arsenopyrite-rich wastes from abandoned tungsten and tin exploitations were studied to determine the composition and characteristics of the secondary phases formed under natural weathering conditions so as to assess their potential environmental risk. Representative weathered arsenopyrite-bearing rock wastes collected from the mine dumps were analysed using the following techniques: X-ray powder diffraction (XRD) analysis, polarizing microscopy analysis, electron microprobe analysis (EMPA) and microRaman and Mössbauer spectroscopies. Scorodite, pharmacosiderite and amorphous ferric arsenates (AFA) with Fe/As molar ratios in the range 1.

Mercury in soils and plants in an abandoned cinnabar mining area (SW Spain).

An abandoned cinnabar mining area located in the South-West of Spain has been studied with the aim of assessing its mercury pollution level and enhancing the knowledge about the Hg soil/plant relationship. To do so, soils and plants were sampled near an inactive smelter and around two mining sites present in this area. Critical total Hg concentrations were found in the close environs of pollutant sources.

Impact of irrigation with arsenic-rich groundwater on soils and crops.

The study was carried out in an intensively cultivated agricultural area of central Spain where high arsenic (As) concentrations in groundwater were previously reported. The concentrations and distribution of As in soils and crops (wheat, potato, sugar beet and carrot) were determined to know the effect of irrigation with As-rich groundwater in the agricultural fields, and to estimate its impact on the food chain contamination. Irrigation water shows high As concentrations ranging between 38 and 136 microg/l.

Approaches for the treatment of waste streams of the aluminium anodising industry.

The aluminium anodising industry is an important industrial sector that invariably generates great amounts of different waste streams. Classical and especially new-developing technologies dealing with them are reviewed. Innovative methods are mainly based on engineering geochemical processes, looking for the recovery of resource materials and the reduction of emissions to the environment.

Risk minimisation of FGD gypsum leachates by incorporation of aluminium sulphate.

The incorporation of aluminium sulphate to (flue gas desulphurisation) FGD gypsum before its disposal was investigated as a way to minimise the risk supposed by the high fluoride content of its leachates. Using a bath method the kinetic and equilibrium processes of fluoride removal by aluminium sulphate were studied at fluoride/aluminium molar concentration (F/Al) ratios in the range 1.75 10(-2)-1.

Trace element mobility in soils seven years after the Aznalcóllar mine spill.

The long-term influence of the Aznalcóllar mine spill on soils was studied seven years after the accident in the area of Vado del Quema. Soils where the pyritic sludge was not removed after the cleaning operations and soils where this process was accomplished successfully were sampled and studied in detail. Sludge and soil horizons were characterised, determining their physico-chemical parameters, mineralogy and the total concentrations of major and trace elements.

Study of the use of coal fly ash as an additive to minimise fluoride leaching from FGD gypsum for its disposal.

The use of coal fly ash as a fluoride retention additive has been studied as a way of treating flue gas desulphurisation (FGD) gypsum for its disposal in landfills. With this end leaching studies following the standard EN-12457-4 [Characterization of waste- Leaching-Compliance test for leaching of granular waste materials and sludges - Part 4: One stage batch test at a liquid to solid ratio of 10l/kg for materials with particle size below 10mm (without or with size reduction)] have been performed on FGD gypsum samples treated with different proportions of fly ash (0.1-100%).

Environmental, physical and structural characterisation of geopolymer matrixes synthesised from coal (co-)combustion fly ashes.

The synthesis of geopolymer matrixes from coal (co-)combustion fly ashes as the sole source of silica and alumina has been studied in order to assess both their capacity to immobilise the potentially toxic elements contained in these coal (co-)combustion by-products and their suitability to be used as cement replacements. The geopolymerisation process has been performed using (5, 8 and 12 M) NaOH solutions as activation media and different curing time (6-48 h) and temperature (40-80 degrees C) conditions. Synthesised geopolymers have been characterised with regard to their leaching behaviour, following the DIN 38414-S4 [DIN 38414-S4, Determination of leachability by water (S4), group S: sludge and sediments.

Implications of moisture content determination in the environmental characterisation of FGD gypsum for its disposal in landfills.

The leachable contents of elements of environmental concern considered in the Council Decision 2003/33/EC on waste disposal were determined in flue gas desulphurisation (FGD) gypsum. To this end, leaching tests were performed following the standard EN-12457-4 which specifies the determination of the dry mass of the material at 105 degrees C and the use of a liquid to solid (L/S) ratio of 10l kg(-1) dry matter. Additionally, leaching tests were also carried out taking into account the dry mass of the material at 60 degrees C and using different L/S ratios (2, 5, 8, 10, 15 and 20l kg(-1) dry matter).

Stabilization of FGD gypsum for its disposal in landfills using amorphous aluminium oxide as a fluoride retention additive.

The applicability of amorphous aluminium oxide as a fluoride retention additive to flue gas desulphurisation (FGD) gypsum was studied as a way of stabilizing this by-product for its disposal in landfills. Using a batch method the sorption behaviour of amorphous aluminium oxide was evaluated at the pH (about 6.5) and background electrolyte conditions (high chloride and sulphate concentrations) found in FGD gypsum leachates.