Abandoned Salt Mine Research Articles

The hydrogeological situation after salt-mine collapses at Solotvyno, Ukraine

Study regionThe study site is located in the south-western part of the Ukraine, in the area of the historical rock-salt mining town Solotvyno. The former mining area is situated in close vicinity to the River Tisza, the main tributary of the Danube River, the largest river in Europe. Study focusAfter uncontrolled flooding of several salt mines, a one month advisory mission was launched by the European Commission to estimate the impact of the abandoned salt mines (containing large quantities of salt water) on the environment. As a consequence of the flooding, dozens of sinkholes formed and sinkhole forming processes are ongoing, with sinkhole diameters reaching 250 m. As river contamination by the release of large quantities of saltwater would lead to an international disaster, hydrogeological measurements were taken on-site to study the system. New hydrological insights of the regionAt the study site, saturated (hyper-saline) water as well as fresh surface and groundwater were encountered in close vicinity to each other. Electrical conductivity, as a proxy for salinity, and temperature were measured on-site and water samples taken from surface-, ground- and mine waters were analyzed for chemistry and stable isotopes, providing new insights into groundwater flow dynamics. A conceptual model shows the salt dome, and potential flow paths from the mining area to the Tisza River, in the context of the mines and associated sinkholes potentially impacting the river water quality.

Opportunities for large-scale energy storage in geological formations in mainland Portugal

This article presents the methodology and results of the first screening conducted in Portugal to identify geological formations suitable for large-scale storage of energy from renewable sources. The screening focused on the identification of adequate porous media rocks, salt formations and igneous host rocks that could act as reservoirs for gas (hydrogen or methane) storage, Compressed Air Energy Storage, Underground Pumped Hydro and Underground Thermal Energy Storage.Public access geological information was collected, compiled in a database and spatially referenced in a GIS environment. The GIS and database were cross-checked with criteria for selecting geological reservoirs and with existing or anticipated spatial, environmental and social constraints. In a third step the feasibility of deploying each large-scale energy storage technology in each prospective reservoir was assessed and classified according to confidence, ranging from unlikely to proven, and to proximity to areas with wind or solar energy potential, accessibility to power transmission lines and natural gas networks.The outcome is a first screening of priority sites to be studied at the local scale in future projects. Early target for detailed studies are the existing salt caverns and an abandoned salt mine in the Lusitanian Basin. Natural gas storage in salt formations is being carried in the region for decades, proving the adequacy of the salt formations and demonstrating the social acceptance. Porous media aquifers in the same Lusitanian basin may also hold an interesting potential, although there is considerable uncertainty due to the scarcity of geological data about deep aquifers. The Sines industrial cluster, in SW Portugal, is another interesting target area, due to the existence of a host rock with proven containment capacity.The technologies with the best potential for application in the Portuguese geologic context seem to be CAES and Underground Gas Storage linked to Power-to-gas projects.

Distinctive molecular and biochemical characteristics of a glycoside hydrolase family 20 \u03b2-N-acetylglucosaminidase and salt tolerance

BackgroundEnzymatic degradation of chitin has attracted substantial attention because chitin is an abundant renewable natural resource, second only to lignocellulose, and because of the promising applications of N-acetylglucosamine in the bioethanol, food and pharmaceutical industries. However, the low activity and poor tolerance to salts and N-acetylglucosamine of most reported β-N-acetylglucosaminidases limit their applications. Mining for novel enzymes from new microorganisms is one way to address this problem.ResultsA glycoside hydrolase family 20 (GH 20) β-N-acetylglucosaminidase (GlcNAcase) was identified from Microbacterium sp. HJ5 harboured in the saline soil of an abandoned salt mine and was expressed in Escherichia coli. The purified recombinant enzyme showed specific activities of 1773.1 ± 1.1 and 481.4 ± 2.3 μmol min−1 mg−1 towards p-nitrophenyl β-N-acetylglucosaminide and N,N'-diacetyl chitobiose, respectively, a Vmax of 3097 ± 124 μmol min−1 mg−1 towards p-nitrophenyl β-N-acetylglucosaminide and a Ki of 14.59 mM for N-acetylglucosamine inhibition. Most metal ions and chemical reagents at final concentrations of 1.0 and 10.0 mM or 0.5 and 1.0% (v/v) had little or no effect (retaining 84.5 − 131.5% activity) on the enzyme activity. The enzyme can retain more than 53.6% activity and good stability in 3.0–20.0% (w/v) NaCl. Compared with most GlcNAcases, the activity of the enzyme is considerably higher and the tolerance to salts and N-acetylglucosamine is much better. Furthermore, the enzyme had higher proportions of aspartic acid, glutamic acid, alanine, glycine, random coils and negatively charged surfaces but lower proportions of cysteine, lysine, α-helices and positively charged surfaces than its homologs. These molecular characteristics were hypothesised as potential factors in the adaptation for salt tolerance and high activity of the GH 20 GlcNAcase.ConclusionsBiochemical characterization revealed that the GlcNAcase had novel salt–GlcNAc tolerance and high activity. These characteristics suggest that the enzyme has versatile potential in biotechnological applications, such as bioconversion of chitin waste and the processing of marine materials and saline foods. Molecular characterization provided an understanding of the molecular–function relationships for the salt tolerance and high activity of the GH 20 GlcNAcase.

Macroscopic Failure Processes at Mines Revealed by Acoustic Emission (AE) Monitoring

Abstract Mining activity may cause different types of seismicity and rock failure. Typical events include (1) fully induced microearthquakes in close proximity to galleries and human activity due to high‐stress concentrations (border fractures) and (2) triggered earthquakes within the rock mass at larger distance to the source of the stress perturbation (inner fractures). Type 1 is important to understand the development of rock bursts and evaluate the stability of the mine. Type 2 may be associated with larger events releasing pre‐existing stress and being triggered by stress changes due to the mining operation. They are important to assess the seismic hazard related to mining activity. To analyze these different failure processes, we use a dataset of high‐frequency acoustic emission (AE) events monitored in an abandoned salt mine. The process of fracture formation in the rock mass was enhanced by the backfilling of a cavity. Thermal stresses induced by the backfilling operation are modeled with a finite‐element approach, and observed AE activity is used to quantify the mechanism of event triggering in terms of a Coulomb failure model. Two observations are outstanding. First, the instantaneous triggering of enhanced activity and the slow growth of an inner fracture in relatively far distance to the backfilled cavity is detected. The structure already showed AE activity before the refilling started and was triggered by traction‐like stress transfer. Its AE activity correlates well with the calculated Coulomb stress changes at the beginning of backfilling. Second, the sudden occurrence of a macroscopic, induced border fracture at the backfilled gallery which is oriented in agreement with the acting stress field is observed. Although AE activity at the inner fracture was triggered by tiny Coulomb stress changes, indicating a structure already in critical state, formation of the border fracture required significantly larger stresses, hinting at a previously intact rock volume. Online Material: Figure depicting the variability of the static Coulomb stress changes on the inner fracture for different rake values.

POSSIBILITY OF INJECTING CO2 INTO THE UNDERGROUND BY BOREHOLES ON POTENTIAL LOCATIONS IN BOSNIA AND HERZEGOVINA

<p>The paper presents the potential areas in Bosnia and Herzegovina (BiH) for injecting CO2 into underground geological formations by boreholes. Areas are determined based on the geological structure of Bosnia ana Herzegovina, and development of Miocene formations which are the most prevalent in the northern and northeastern parts of the country, in the central part of country and southwest of Bosnia and Herzegovina. Furthermore paper gives an overview of potentials for injecting CO2 into abandoned coal mines, and abandoned salt mine.</p>

Long-term time-lapse microgravity and geotechnical monitoring of relict salt mines, Marston, Cheshire, U. K.

The area around the town of Northwich in Cheshire, U. K., has a long history of catastrophic ground subsidence caused by a combination of natural dissolution and collapsing abandoned mine workings within the underlying Triassic halite bedrock geology. In the village of Marston, the Trent and Mersey Canal crosses several abandoned salt mine workings and previously subsiding areas, the canal being breached by a catastrophic subsidence event in 1953. This canal section is the focus of a long-term monitoring study by conventional geotechnical topographic and microgravity surveys. Results of 20 years of topographic time-lapse surveys indicate specific areas of local subsidence that could not be predicted by available site and mine abandonment plan and shaft data. Subsidence has subsequently necessitated four phases of temporary canal bank remediation. Ten years of microgravity time-lapse data have recorded major deepening negative anomalies in specific sections that correlate with topographic data. Gravity 2D modeling using available site data found upwardly propagating voids, and associated collapse material produced a good match with observed microgravity data. Intrusive investigations have confirmed a void at the major anomaly. The advantages of undertaking such long-term studies for near-surface geophysicists, geotechnical engineers, and researchers working in other application areas are discussed.

Airborne and ground geophysical investigation of the abandoned salt mine environment along the Stassfurt-Egeln Anticline, Germany

In the area of the 1200-year-old town of Stassfurt, where the world’s first potash mine was opened in 1852, sinkholes emerged during mining and the town’s centre slowly subsided. Mining has increased the subsidence due to collapses and uncontrolled flooding of abandoned salt mineworkings, the dissolution of salt in the mines, and the pump-driven drainage system. In order to investigate possible consequences of salt-mine flooding, this area was selected for the study of the dynamic processes in flooded or abandoned mineworkings and their overburden. As part of a multi-disciplinary research project, the German Federal Institute for Geosciences and Natural Resources (BGR) conducted an airborne geophysical survey covering the salt anticline in summer 2007 with the aim of acquiring extensive electrical conductivity datasets to show the regional hydrogeological and geological structures down to about 100 m depth. Areas with distinct conductivity anomalies were subsequently selected for more detailed studies using ground geophysical methods such as DC geoelectrics and transient electromagnetics (TEM). The conductivity data revealed several hydrogeologically important features, such as the distribution of salt water, areas of salt-water rise, Quaternary channels, and fresh-water influxes. The airborne data also served as base-line data for ground follow-up studies and 3D hydrogeological and geological modelling.

Wyrobiska solne jako przestrzeń urbanistyczna

Abstract: This paper points out particular significance of salt workings in abandoned salt mines which, owing to speci? c features and values, can be used for stimulation of the development and the increase of the attractiveness of salt mining towns as former industrial centres. The authors emphasized the need of choice of a proper direction of remodelling and adaptation of salt workings to attain possibly a complete display and preservation of unique values, with making the salt mine available to various types of users.

Stress triggering and stress memory observed from acoustic emission records in a salt mine

SUMMARY Some of the most interesting questions in geosciences are whether results from laboratory experiments can be applied to processes in the earth crust and whether in situ studies with high spatio-temporal resolution can bridge the gap between laboratory work and seismology. In this study, acoustic emission (AE) activity caused by stress changes due to the backfilling of a cavity in an abandoned salt mine is studied to answer questions regarding (1) the dependence of AE event rates, event distribution and b-value on the stress state, (2) the stress memory effect of rock (Kaiser effect), (3) the possibility to detect significant changes in the system like the initiation of macrocracks and (4) the possibility to estimate future activity from previous AE records. The large number of events studied (>3 × 10 5 ) allows a spatial resolution of the order of 1 m and a temporal one on the order of 1 hr. Stress changes are created due to the thermal expansion and contraction of the rock mass in response to the temperature changes caused by the backfilling. A roughly 20 × 50 × 50 m section of the mining complex just above the backfilled cavity is well covered by a network of 24 piezo-electric receivers and poses an optimal volume for the study. Results of a 2-D finite element thermoelastic stress model are in agreement with the spatio-temporal AE event distribution. In addition to the initial upward migration of the AE event front, which correlates with the calculated stress field, the rock salt exhibits a pronounced Kaiser effect for the first few thermal loading cycles throughout the whole study region. The deviation from the Kaiser effect during later loading cycles seems to be caused by the initiation of a planar macroscopic crack, which is subsequently reactivated. AE activity tends to concentrate along this macrocrack. Calculated b-values decrease before and increase after the supposed initiation of the macrocrack supporting this explanation. In intact rock volumes not subjected to macrocracking a linear relation between the maximum event rate and the calculated absolute Coulomb stress increase is observed. This indicates that future maximum AE event rates can be estimated from expected loading. AE activity during stress loading cycles is most prominent in regions with Coulomb stress maxima indicating possible shear cracking that has the potential to create macrocracks. Strong bursts of AE activity observed during thermal unloading phases are concentrated in regions for which the minimum principal stress becomes tensile. These regions exhibit significantly higher b-values than those active during thermal loading. We interpret these weak events with tensile microcracking.

Subsidence map development in an area of abandoned salt mines

Purpose of the study Morphological mapping is not generally associated with mining and subsidence, having traditionally been used to define the nature and extent of surface features such as landslides and landforms. However, detailed morphological mapping, linked to subsurface investigation, can provide a preliminary indication of potential subsidence hazards in some areas of abandoned mine workings. This example describes how mapping was carried out in an undeveloped part of the Cheshire saltfleld, prior to any subsurface investigation, with the aim of establishing the likely extent to which a number of mines had collapsed. The site The site is in the Northwich area of Cheshire, England, and has had a long history of rock salt mining and brine pumping. The site is largely undeveloped, although locally important infrastructure routes cross the area, and it has potential for use as a community woodland and open space area. At the site, rock salt (halite) occurs in two discrete horizons within the Triassic Mercia Mudstone sequence, separated by around 10 m of marls: the 20–30 m thick Top Bed (at c . 40 m b.g.l.) and the 23–28 m thick Bottom Bed (at c . 75 m b.g.l.). This sequence is overlain by glacial till. Salt was extensively mined at the site from around 1777 to 1933, with the one Top Bed and seven Bottom Bed mines opened over this period, varying in size from 0.8 to 13 ha.

The thermomigration of biphase vapor-liquid droplets in solids

The thermomigration of biphase vapor-liquid droplets was studied in KCl as a function of droplet size and the relative proportions of gas and liquid phases in the droplets. Droplets containing more than 10 vol. % of gas migrated down thermal gradients toward lower temperatures in contrast to the usual thermomigration behavior of simple gas or liquid inclusions up thermal gradients in solids. By considering viscous gas flow, vapor diffusion, liquid diffusion, evaporation and condensation and liquid currents driven by surface tension gradients, the observed thermomigration behavior of biphase vapor-liquid droplets can be adequately explained. The results of this and previous investigations were applied to the thermomigration problems associated with the proposed storage of highly radioactive waste products in abandoned salt mines. The thermomigration of naturally occurring brine droplets in a salt formation up thermal gradients generated by the vigorous self heating of these nuclear wastes is shown to be capable of causing an undesirable inflow of water into the nuclear waste crypts. In addition, the thermomigration of contaminated vapor-liquid droplets created on the salt crypt walls in a direction away from the crypt may lead to a modest dispersal of radioactive wastes in the salt formation. Droplet migration along the gravitational field or along the weak natural thermal gradient of the earth would be prevented by the trapping of droplets on grain boundaries in the salt. Thus, the escape of radioactivity to the outside environment is unlikely even on a geological time scale.