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1.
Abstract.
This paper describes pilot scale tests of a novel process for the neutralisation of acidic mine water. Leachate from a waste coal dump was neutralised with limestone, and iron, aluminium, and sulphate were removed. Specific aspects studied were: the process configuration; the rates of iron oxidation, limestone neutralisation, and gypsum crystallisation; the chemical composition of the effluents before and after treatment; the efficiency of limestone utilisation; and the sludge solids content. The acidity was decreased from 12,000 to 300 mg/L (as CaCO3), sulphate from 15,000 to 2,600 mg/L, iron from 5,000 to 10 mg/L, aluminium from 100 to 5 mg/L, while the pH increased from 2.2 to 7.0. Reaction times of 2.0 and 4.5 h were required under continuous and batch operations respectively for the removal of 4 g/L Fe (II). The iron oxidation rate was found to be a function of the Fe (II), hydroxide, oxygen, and suspended solids (SS) concentrations. The optimum SS concentration for iron oxidation in a fluidised-bed reactor was 190 g/L. Up-flow velocity had no influence on the rate of iron oxidation in the range 5 to 45 m/h. Sludge with a high solids content of 55% (m/v) was produced. This is high compared to the typical 20% achieved with the high density sludge process using lime. It was determined that neutralisation costs could be reduced significantly with an integrated iron oxidation and limestone neutralisation process because limestone is less expensive than lime, and a high-solids-content sludge is produced. Full scale implementation followed this study. 相似文献
2.
A. K. Soni 《Mine Water and the Environment》2007,26(2):110-118
Abstract. Hydrogeological study of the Manikgarh and Naokari limestone mining areas, located in the Chandrapur region of central India,
indicate that the mining operations should not cause environmental problems. Conversion of hill mining to pit mining at the
Manikgarh Limestone Mine should be feasible and safe. At the Naokari Limestone Mine, a partial diversion of a seasonal stream,
the Bop Nala, has been proposed to simplify mining and maximize production; this can be done without significantly altering
the natural drainage pattern of the area and is not expected to have any adverse effects on the hydrological regime of area. 相似文献
3.
Abstract A demonstration project was conducted to investigate treating acid mine water by alkaline injection technology (AIT). A total
of 379 t of alkaline coal combustion byproduct was injected into in an eastern Oklahoma drift coal mine. AIT increased the
pH and alkalinity, and reduced acidity and metal loading. Although large improvements in water quality were only observed
for 15 months before the effluent water chemistry appeared to approach pre-injection conditions, a review of the data four
years after injection identified statistically significant changes in the mine discharge compared to pre-injection conditions.
Decreases in acidity (23%), iron (18%), and aluminum (47%) were observed, while an increase in pH (0.35 units) was noted.
Presumably, the mine environment reached quasi-equilibrium with the alkalinity introduced to the system. 相似文献
4.
Charles A. Cravotta III Robin A. Brightbill Michael J. Langland 《Mine Water and the Environment》2010,29(3):176-199
Acidic mine drainage (AMD) from legacy anthracite mines has contaminated Swatara Creek in eastern Pennsylvania. Intermittently
collected base-flow data for 1959–1986 indicate that fish were absent immediately downstream from the mined area where pH
ranged from 3.5 to 7.2 and concentrations of sulfate, dissolved iron, and dissolved aluminum were as high as 250, 2.0, and
4.7 mg/L, respectively. However, in the 1990s, fish returned to upper Swatara Creek, coinciding with the implementation of
AMD treatment (limestone drains, limestone diversion wells, limestone sand, constructed wetlands) in the watershed. During
1996–2006, as many as 25 species of fish were identified in the reach downstream from the mined area, with base-flow pH from
5.8 to 7.6 and concentrations of sulfate, dissolved iron, and dissolved aluminum as high as 120, 1.2, and 0.43 mg/L, respectively.
Several of the fish taxa are intolerant of pollution and low pH, such as river chub (Nocomis micropogon) and longnose dace (Rhinichthys cataractae). Cold-water species such as brook trout (Salvelinus fontinalis) and warm-water species such as rock bass (Ambloplites rupestris) varied in predominance depending on stream flow and stream temperature. Storm flow data for 1996–2007 indicated pH, alkalinity,
and sulfate concentrations decreased as the stream flow and associated storm-runoff component increased, whereas iron and
other metal concentrations were poorly correlated with stream flow because of hysteresis effects (greater metal concentrations
during rising stage than falling stage). Prior to 1999, pH < 5.0 was recorded during several storm events; however, since
the implementation of AMD treatments, pH has been maintained near neutral. Flow-adjusted trends for 1997–2006 indicated significant
increases in calcium; decreases in hydrogen ion, dissolved aluminum, dissolved and total manganese, and total iron; and no
change in sulfate or dissolved iron in Swatara Creek immediately downstream from the mined area. The increased pH and calcium
from limestone in treatment systems can be important for mitigating toxic effects of dissolved metals. Thus, treatment of
AMD during the 1990s improved pH buffering, reduced metals transport, and helped to decrease metals toxicity to fish. 相似文献
5.
Jae E. Yang Jeffrey G. Skousen Yong-Sik Ok Kyung-Yoal Yoo Hee-Joung Kim 《Mine Water and the Environment》2006,25(4):227-232
Abstract. There are hundreds of abandoned coal mines in Korea's steep mountain valleys. Enormous amounts of coal waste from these mines
were dumped on the slopes, contaminating streams with sediment and acid mine drainage. A limestone slurry by-product (lime
cake), which is produced during the manufacture of soda ash, was investigated for its potential use in reclaiming the coal
waste. The lime cake is fine grained, has low hydraulic conductivities (10-8 to 10-9 cm sec-1), high pH, high electrical conductivity, and trace amounts of heavy metals. A field experiment was conducted; each plot was
20 x 5 m in size on a 56% slope. Treatments included a control (waste only), lime (CaCO3), and lime cake. The lime requirement (LR) of the coal waste to pH 7.0 was determined; treatments consisted of adding 25,
50, and 100% of the LR. The lime cake and lime were applied either as a layer between the coal waste and topsoil or mixed
into the topsoil and waste. Each plot was hydroseeded with grasses, and planted with trees. In each plot, soils, surface runoff,
and subsurface water were collected and analyzed, and plant cover was measured. Lime cake treatments increased the pH of the
coal waste from 3.5 to 6, and neutralized the pH of the runoff and leachate of the coal waste from 4.3 to 6.7. Moreover, the
surface cover of seeded species was significantly increased; sufficient acidity in the coal waste was neutralized in the 25%
LR plots to allow seed germination. 相似文献
6.
D. H. M. Alderton T. Serafimovski B. Mullen K. Fairall S. James 《Mine Water and the Environment》2005,24(3):139-149
Abstract Pollution from current and past mining is a significant problem in several parts of the former Yugoslav Republic of Macedonia.
Water from six different mining areas in Macedonia was analysed to assess the effects of metalliferous mining activities.
Drainage sediments at all locations show evidence of physical and chemical contamination; water compositions, however, were
more variable. Low pH water associated with mining has led to the dissolution of minerals and the mobilization of metals from
the ores and the host rocks. Only Sb was noted to exhibit enhanced mobility in higher pH waters. The Zletevo Pb-Zn mine discharges
low pH water that has high levels of several metals, including Al, Zn, Cd, and Fe; sediment concentrations are grossly elevated
for several km downstream. Toranica and Sasa Pb-Zn mines exhibit similar sediment contamination of Pb, Zn, Cd, and other ore-related
metals. However, concentrations of metals in waters are far lower at both of these mines, due to less pyrite in the ore and
the buffering of the acid waters by carbonate host lithologies. At the Buchim copper mine, waters are both acidic and high
in dissolved solids; Cu concentrations exceed 100 mg/L. Krstov Dol and Alshar are small, disused As-Sb mines that discharge
waters that exceed potable values for some contaminants (e. g. As), but this may be related to the mineralization of the bedrock
rather than the mines. In general, metal concentrations decreased downstream from the source due to dilution from other rivers
and coprecipitation of metals on other mineral phases (e. g. Fe-, Al- and Mn-oxides, and hydroxides). 相似文献
7.
Abstract. The basic chemical properties of Tertiary (T) and Quaternary (Q) aquifers near the Piaseczno opencast sulphur mine and the
water in the open pit, along with the stratigraphy and hydrogeology of the area, were characterized to assess the feasibility
of inundating the mine with ground water. Ground water quality varied markedly in the opencast area. A distinct stratification
was noted in the pit water; total dissolved solids, calcium, chloride, hardness, and hydrogen sulphide increased from the
top water level to the bottom of the pit lake. The concentrations of SO42- and Cl- in the opencast water were very high, especially in the hypolimnion zone. Based on our preliminary analysis, it appears that
an artificial lake formed in the Piaseczno open pit could be used in the future as a fish and wildlife habitat as well as
for recreational purposes. 相似文献
8.
Biswajit Mukhopadhyay Luciano Bastias Anosua Mukhopadhyay 《Mine Water and the Environment》2007,26(1):29-45
Abstract. Limestone drains are an integral component of some of the most efficacious passive systems for the treatment of acid rock
drainage (ARD). A critical design parameter for a limestone drain is the mass of limestone that will be required for effective
treatment. This in turn depends on the flow rate, limestone dissolution rate, and associated hydraulic detention time necessary
to achieve a certain effluent alkalinity for a given design life. Rates of alkalinity generation and limestone dissolution,
and the quality of the limestone in terms of weight fraction of CaCO3 and percentage CaCO3 available must be known to determine the required mass of limestone. These parameters were experimentally determined for
a natural and synthetic suite of ARD waters. The experimental results show that the empirical change in the alkalinity over
time cannot simply be modeled as a first-order process. During the initial stage, the concentration increase is extremely
fast, giving a linear and steep rise in the alkalinity. Alkalinity concentrations peaked at elapsed times of 90 to 180 minutes
and then declined to a nearly constant value. The decline in alkalinity corresponds with a decline in concentrations of dissolved
iron and aluminum, implying that the consumption of alkalinity by the hydrolysis of these metals is faster than the rate of
alkalinity production by the dissolution of limestone, so that the reaction appears zero order in the early stage and pseudo-first
order later. Because the changes in concentration were complex, considerable uncertainty exists in the rate constants for
estimating alkalinity concentration. This causes problems in design equations based solely on a limestone dissolution rate
that is estimated from alkalinity generation rates. A more applicable design procedure, combining the kinetics of alkalinity
production and consumption with the hydraulics and chemical equilibrium of the system, is illustrated.
Research was conducted while the first and third authors were with Ecology and Environment, Inc, Dallas, TX, USA; 相似文献
9.
Abstract.
State and federal reclamation programs, mining operators,
and citizen-based watershed organizations have constructed
hundreds of passive systems in the eastern U. S. over the past
20 years to provide reliable, low cost, low maintenance mine
water treatment in remote locations. While performance has been
reported for individual systems, there has not been a
comprehensive evaluation of the performance of each treatment
type for a wide variety of conditions. We evaluated 83 systems;
five types in eight states. Each system was monitored for
influent and effluent flow, ph, net acidity, and metal
concentrations. Performance was normalized among types by
calclating acid loading reductions and removals, and by
converting construction cost, projected service life, and metric
tonnes of acid load treated into cost per tonne of acid treated.
Of the 83 systems, 82 reduced acid load. Average acid load
reductions were 9.9 t/yr for open limestone channels (OLC), 10.1
t/yr for vertical flow wetland (VFW), 11.9 t/yr for anaerobic
wetlands (AnW), 16.6 t/yr for limestone leach beds (LSB), and
22.2 t/yr for anoxic limestone drains (ALD). Average costs for
acid removal varied from $83/t/yr for ALDs to $527 for AnWs.
Average acid removals were 25
g/m2/day for AnWs, 62
g/m2/day for VFWs, 22 g/day/t for
OLCs, 28 g/day/t for LSBs, and 56 g/day/t for ALDs. It appears
that the majority of passive systems are effective but there was
wide variation within each system type, so improved reliability
and efficiency are needed. This report is an initial step in
determining passive treatment system performance; additional
work is needed to refine system designs and monitoring. 相似文献
10.
Abstract.
Design criteria were developed for the construction of a full-scale limestone neutralization plant to treat leachate from the waste rock of a nickel mine, using data from laboratory studies, pilot-scale studies, and operation of a full-scale limestone handling and dosing facility. We learned that: limestone powder can be slurried to a constant slurry density of 60 g/L; Fe (II) can be oxidised at low pH (2.5) at a rate of 16.1 g/(L/d) using geotextile as a medium; and that the integrated Fe (II)-oxidation and limestone neutralization process allows neutralization, Fe (II)-oxidation, and gypsum crystallization to take place at the same time, provided that the solids concentration is high (greater than 30 g/L). A full-scale plant with a capacity of 50 m3/h was designed and constructed. The plant consists of the following stages: biological Fe (II)-oxidation, a fluidised-bed limestone neutralization reactor, a complete-mix gypsum crystallization reactor, and a clarifier. 相似文献
11.
Larry G. Twidwell Christopher H. Gammons Courtney A. Young Richard B. Berg 《Mine Water and the Environment》2006,25(2):86-92
Abstract. Unconsolidated sediment at the bottom of the Berkeley pit lake is a mixture of detrital silicate minerals derived from sloughing
of the pit walls and secondary minerals precipitated out of the water column. The latter include gypsum and K-rich jarosite.
The pore waters have a similar pH to the overlying lake waters (pH 3.1 to 3.4), and have similarly high concentrations of
dissolved heavy metals, including Al, Cd, Cu, Mn, Ni, and Zn. Sediment cores show that the top meter of the sediment column
is moderately oxidized (jarosite-stable). Petrography, chemical analysis and geochemical modelling all suggest a transformation
of poorly crystalline ferric compounds such as schwertmannite and/or ferrihydrite near the sediment surface to jarosite with
depth in the core. No evidence of bacterial sulfate reduction was found in this study, despite the presence of 0.3 to 0.4
wt% organic carbon in the pit lake sediment. 相似文献
12.
Oliver Totsche Andrew Fyson Christian E. W. Steinberg 《Mine Water and the Environment》2006,25(4):204-213
Abstract. Microbial alkalinity production was evaluated as a method to prevent reacidification of neutralized mining lakes by acidic
ground and seepage water. We used 60 L mesocosms to represent the sediment and water column of a shallow acidic mine lake.
To enhance alkalinity production, acidic and neutralized lake waters were treated with either phosphorus (controlled eutrophication)
or organic matter (controlled saprobization). Controlled eutrophication could not produce enough autochthonous biomass as
substrate for microbial alkalinity production to change the acidity of the water. Chemical pre-neutralization of the acidic
water caused the inorganic carbon concentration to increase, but at the same time, hindered algae growth by reducing the availability
of phosphate by sorption to the freshly precipitated iron hydroxide. This effect was so strong that even high phosphorus additions
could not increase the algae biomass production. In contrast to controlled eutrophication, controlled saprobization produced
significant alkalinity. Despite inhibition of the most important alkalinity producing process, namely microbial sulfate reduction,
by low pH values, the microbial alkalinity production rate was not affected by pre-neutralization of the water column. Other
alkalinity producing processes raised the pH in the reactive zone until sulfate reduction was no longer inhibited. 相似文献
13.
Abstract. High-resolution airborne thermal infrared (TIR) imagery
data were collected over 90.6 km2 (35
mi2) of remote and rugged terrain in
the Kettle Creek and Cooks Run Basins, tributaries of the West
Branch of the Susquehanna River in north-central Pennsylvania.
The purpose of this investigation was to evaluate the
effectiveness of TIR for identifying sources of acid mine
drainage (AMD) associated with abandoned coal mines. Coal mining
from the late 1800s resulted in many AMD sources from abandoned
mines in the area. However, very little detailed mine
information was available, particularly on the source locations
of AMD sites. Potential AMD sources were extracted from airborne
TIR data employing custom image processing algorithms and GIS
data analysis. Based on field reconnaissance of 103 TIR
anomalies, 53 sites (51%) were classified as AMD. The AMD
sources had low pH (<4) and elevated concentrations of iron
and aluminum. Of the 53 sites, approximately 26 sites could be
correlated with sites previously documented as AMD. The other 27
mine discharges identified in the TIR data were previously
undocumented. This paper presents a summary of the procedures
used to process the TIR data and extract potential mine drainage
sites, methods used for field reconnaissance and verification of
TIR data, and a brief summary of water-quality data. 相似文献
14.
Using the DRASTIC System to Assess the Vulnerability of Ground Water to Pollution in Mined Areas of the Upper Silesian Coal Basin 总被引:2,自引:1,他引:1
Abstract An attempt was made to use the U.S. EPA DRASTIC ranking system to assess the vulnerability of ground water in the Upper Silesian
Coal Basin. Analysis of the various system components indicate that several DRASTIC factors would have to be modified to consider
the effects of mining, subsidence, and ground water rebound. 相似文献
15.
Abstract. Surface water bodies are expected to form in several pits
at the Getchell Open Pit Mine after mining has ceased due to
inflowing surface and ground water. Predicting the long-term
geochemical behavior of the pit water is important in assessing
potential environmental effects. One of the pits, the Summer
Camp Pit, began to develop a pit lake in 1991 when dewatering
ceased and the pit was used to store water pumped from
underground operations. This provided a field-scale opportunity
to identify the controls on lake water chemistry and determine
the effects of seasonal mixing events on long-term chemical
behavior. During a five-year period (1996-2001), a number of
physical, chemical and mineralogical characteristics of the lake
were monitored with the intent of using this information as a
basis for predicting long-term geochemical behavior of future
lakes in the other pits. Seasonal and multiyear cycles were
identified within the water column. These cycles were influenced
by climatic changes and element and sediment loadings of inflow
to the lake. Stratification occurred, with the metalimnion or
active layer of the lake evolving from a low total dissolved
solids (TDS), alkaline water to a high TDS, neutral to mildly
acidic water, until turnover occurred due to density variations
between the metalimnion and epilimnion, completely mixing the
layers. A hypolimnion that formed has the potential to stabilize
metals in the basal sediments as sulfide minerals below a
chemolimnion in the lake. Longer-term events also appear to
involve the hypolimnion.The monitoring program demonstrated the dynamic nature of
a pit lake and how the complex limnology can affect seasonal
water quality. Such considerations are important in interpreting
water quality from pit lakes and in selecting monitoring data to
use when constructing mathematical models for predicting changes
in water quality. 相似文献
16.
Abstract. The removal of sulphate and metals from mine water was assessed using the integrated barium carbonate process and the co-precipitation
of barium sulphate with calcium carbonate. The rate of sulphate removal was influenced by the BaCO3 concentration and the cation associated with sulphate, and increased with increasing BaCO3-concentration. BaCO3 can only be used for removal of sulphate that is associated with calcium, as calcium is needed to remove the added carbonate
associated with the barium cation. Sulphate removal was only marginally influenced by alkalinity. Sulphide can be stripped
with CO2 from a BaS-solution. The (CO2 dosed/sulphide removed) molar ratio was close to unity for the first 50% of sulphide in solution. The stripped H2S-gas can be absorbed into zinc acetate. BaSO4 and CaCO3 can be converted simultaneously to BaS and CaO, respectively at an optimum temperature of 1050°C. The CaCO3/BaSO4 molar ratio has little influence on the yield of BaS. The running cost of the barium carbonate process for the removal of
2 g/L of sulphate totalled ZAR1.28/m3 (US$1.00 = ZAR7.0, Feb 2007), the capital redemption cost was R1.08/m3, and the value of the products (water and sulphur) totalled R2.76/m3. 相似文献
17.
Abstract. The concentration of dissolved organic carbon (DOC) in the Berkeley pit lake water ranges from 2 to 4 mg/L, and is comparable
to that of its inflow waters. On the dates sampled, the DOC concentrations decreased towards the surface of the lake, in a
manner similar to the concentration of dissolved Fe. This may reflect adsorption of DOC onto newly formed ferric precipitates
in the epilimnion of the lake. The total organic carbon (TOC) content of the lake sediment is 0.20 to 0.33%, and is on the
low end of TOC in natural aquatic sediments. In contrast, the DOC concentrations of sediment pore waters are unusually high,
ranging from 50 to 380 mg/L, and are much higher than DOC values of pore waters from typical marine or lacustrine sediments.
The high DOC concentrations are explained by release of adsorbed organic carbon from ferric precipitates as they age and recrystallize,
coupled with the relative scarcity of heterotrophic bacteria in the acidic and heavy metal-rich waters that would otherwise
consume DOC through reduction of sulfate. 相似文献
18.
Abstract.
The integrated barium sulphide process consists of: preliminary treatment with lime, sulphate precipitation as barium sulphate, H2S-stripping, crystallization of CaCO3, and recovery of barium sulphide. Our tests showed that during lime pre-treatment, sulphate was lowered from 2 800 mg/L to 1 250 mg/L by gypsum crystallization; metals were precipitated as hydroxides. The BaS treatment then lowered sulphate to less than 200 mg/L. Sulphide was lowered from 333 to less than 10 mg/L (as S) in the stripping stage, using CO2 gas for stripping. The stripped H2S-gas was contacted with Fe (III)-solution and converted quantitatively to elemental sulphur. The alkalinity of the calcium bicarbonate-rich water was reduced from 1 000 to 110 mg/L (as CaCO3) after CO2-stripping with air due to CaCO3 precipitation. Fe (II), after sulphur production, was re-oxidized to Fe (III) using an electrolytic step. The running cost of the BaS process is R2.12/m3 (US$1 = SAR6.5) for the removal of 2 g/L of sulphate. 相似文献
19.
Abstract. In the Eastern Middle Anthracite field of Pennsylvania, a
formerly acidic (pH = 3.6) surface mine lake (initially
approximately 45,000m3 in volume) is
being reclaimed using fluidized bed combustor (FBC) ash. The pH
of the water in the pit dramatically increased when the alkaline
ash was added. The pH of the water is now well buffered, and has
not dropped below a value of 11.0 since March 2000. Analysis of
data from samples collected over the past six years indicate
that the lakes alkalinity is controlled by carbonate, silicate,
and hydroxide reactions. The relative importance of these
factors varies with ash input, and can be determined in a
predictable fashion. Laboratory tests determined that the mass
of CaO was more significant than the particle surface area on
the pH of the solution. Using only alkaline material, the
transition between caustic and carbonate alkalinity was
apparent, though this did not account for interaction with
silicate minerals, which should be considered when using
alkaline ash for reclamation. Field data indicate that with
time, the pH will again decrease but will be buffered by calcite
present on both the upper walls of the mine pool and within
pores of the FBC ash. Less than 1% of the ash is currently used
to increase the pH and alkalinity, so a large reserve exists for
long term buffering capacity. 相似文献
20.
Abstract Passive treatment of acid mine drainage (AMD) requires a combined strategy to minimize the effect of climatic variability
on the treatment performance of the system. A vertical-flow combined passive treatment system was developed and evaluated
in a bench-scale laboratory test for a 290-day period. The combined system consisted of four components with specific treatment
functions: an oxidation/precipitation basin for excess iron removal; a peat biofilter for heavy metal sorption and the establishment
of anoxic conditions; a bioreactor for alkalinity generation and sulphate reduction; and an anoxic limestone drain for alkalinity
addition. The benchscale system was dosed with moderate strength synthetic AMD at a surface loading of 95 L/m2/d, and operated under continuous flow conditions. Removal efficiencies were 99.7%, 99.9%, 99.9%, 98.6%, 98.2%, and 99.9%
for Fe, Al, Zn, Mn, Ni, and Cu, respectively, while Cd remained more mobile with a removal efficiency of 66.5%. Sulphate concentrations
were reduced from 3030 mg/L to 814.9 mg/L and the acidic drainage was neutralized to an effluent pH of 7.2 and an alkalinity
of 1353.6 mg/L (as CaCO3). 相似文献