Lye inflows into the salt mines of southwest Mecklenburg

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Nothing in salt mining is more alarming than the sudden appearance of alkalis or even water , since if uncontrolled they ultimately lead to the affected mines drowning. There are many examples of this, be it salt-mining pits on salt saddles (several pits in the Staßfurt Revier) or on salt domes (such as the one in southwest Mecklenburg). The caustic inflow of these Mecklenburg potash and rock salt mines Jessenitz and Lübheen led to the rapid drowning of both pits after only a few years of mining activity. These events as well as the caustic situation at the Conow potash and rock salt mine will be considered here below.

Location of the salt mines in southwest Mecklenburg.

Preliminary remarks

The subsoil of southwest Mecklenburg is rich in salt deposits that were deposited in several episodes during the Zechstein . The salt tectonics in northern Germany mainly affects Mesozoic and Cenozoic layers and is caused by the salts of the Zechstein formation. Several salt domes broke through the overlying layers in southwest Mecklenburg (see map section above). The gypsum hat (caprock) of the Lübenheen salt dome even reaches the surface of the earth. The gypsum on the surface here was extracted from open-cast mining from 1830 to 1894 and processed into fertilizer, mortar and plastering gypsum . But the deeper the plaster of paris was broken, the more salty was the pit water . The assumption that rock salt is lying under the gypsum was confirmed by a shallow drilling.

The mining of potash and rock salt from the Lübenheen-Jessenitz salt dome took place between 1900 and 1916 using two pits, the Jessenitz and Lübenheen potash works. From 1914 to 1926, potash and rock salt were also mined from the Conow salt dome , located southeast of the Lübenheen-Jessenitz salt dome .

Nowadays, the salt structures are in the focus of further possible uses: "Due to its mechanical properties, rock salt offers excellent opportunities for cavern construction in the accumulation areas for underground storage of gases and liquids. Due to the lower depth, the interest is primarily directed towards the salt domes The core area is usually several thousand meters of Leine and Staßfurt rock salt folded in steeply ".

The lye problem in salt mining in general

Every branch of mining has its own particular sources of danger. From the very beginning, salt mining in Zechstein learned to fear water and lye as its greatest enemy. How serious this risk has already been judged is very aptly expressed in the phrase coined around the turn of the century: " Every potash plant must drown once ". Structures in which the potash seams and the main anhydrite reach up to the salt level are particularly endangered. In the case of the former, a distinction must be made between the chlorine-magnesium-free ( sylvinite , kainite and hard salt ) and the chlorine-magnesium-containing potassium salts ( carnallite ) with regard to the risk of alkali due to their water solubility .

Many scientific studies and documentations have been devoted to this topic. Recently, for example, as part of the joint research project "Dynamics of Sunk or Flooded Salt Mines and their Overburden Levels " , Bach investigated the kinetic processes involved in drowning the Staßfurt potash mines and Jahnke , Bohn , Walter and Voigt the hydrogeological and hydrochemical conditions of the former Staßfurt potash salt mines on the western flank Staßfurt saddle and the overburden. The investigations have not yet been completed and can therefore only be evaluated in the final report of the joint project (probably in 2013).

The two mining salt domes of southwest Mecklenburg

The geological conditions

The Lübenheen-Jessenitz salt dome strikes in a north-west-south-east direction and sits on an approximately 17-kilometer-long and approximately ten-kilometer-wide northwest-facing salt foot. The salt level is −240 m above sea ​​level . The breakthrough of the salt dome happened about 100 million years ago in the Alb . The further rise of the salt took place about 55 million years ago in the Tertiary and its main development phase is dated to the Oligocene (about 25 million years ago) and Neogene (about 5 million years ago). The rise in terrain over the salt dome indicates recent ascent movements.

Schematic profile through the salt dome of Lübenheen-Jessenitz (after E. Geinitz 1921)

The deep boreholes sunk on the salt dome as well as the excavations in the Jessenitz mine itself and those of the Friedrich Franz Lübheen potash and rock salt mine about two kilometers away do not allow sufficient clarification of the geological structure of the salt structure. Pleistocene and tertiary strata (less than a million years old) form the overburden above the salt dome. The Pleistocene (approx. 10,000 years ago), which consists of yellow sands and gravel , follows under about 2 m of fine yellowish heather sand, which is often merged into dunes and crossed by boggy lowlands . In places, these several meters thick are boulder clay layers and those with coarse pebbles underlain. This non-cohesive and cohesive rocks reach up to 40 m in thickness .

So-called pinges , which are caused by leaching in the salt mountains, by crevasses in the gypsum hat above and by saline-tectonic disturbances, lie in a wide, northwest-southeast running zone above the salt dome and make its course transparent on the surface of the salt. The most important ones are the 6.4 hectare lake in Probst Jesar See , the Big and Small Sarm near Trebs and the so-called Kirchenversunk near Volzrade . Other small pings are in the Kamdohl forest area.

Tertiary deposits are present as clays , mica and glauconite sands as well as “earthy” lignite . On the flanks of the salt dome, the Tertiary reaches down to a depth of 550 m.

Schematic representation of the Lübenheen-Jessenitz and Conow salt domes

The saline developed through the mine workings of the "Herzog-Regent" Jessenitz mine can generally be broken down as follows:

  • Zechstein 3 (Z 3, Leine series):
Main anhydrite (mostly very fissured, A 3); up to 120 m thick.
Gray salt tone (T 3); up to 2 m thick.
  • Zechstein 2 (Z 2, Staßfurt series):
Deck anhydrite (fissured and leading to gaps, A 2r); up to 110 m thick.
Reddish brown to grayish white capstone salt (Na 2r); up to 250 m thick.
Kaliflöz Staßfurt (K 2, hanging group; partly pure white carnallite ); 5 m, in compression zones even up to 50 m thick.
Rock salt intermediate, consisting of gray rock salt, up to 8 m thick.
Kaliflöz Staßfurt (K 2, lying group; red carnallite); 10 m, in compression zones even up to 60 m thick.
Staßfurt rock salt Na 2.

(Note: Since 2007 the previous 34 formations of the basin facies in the Zechstein have been reduced to 7 formations. Zechstein 3 is the abbreviation zL, Zechstein 2 is the abbreviation zS, etc.)

Steep and almost vertical strata position, bends, tapering and wedges of strata are indicative of strong salt tectonic movements. Dry as well as caustic and gas-filled fissures were found in abundance through the drilling and mining excavations. For example, when the shaft was being sunk at a depth of 508 m on the western face, an open, dry and z. The gap between carnallite and rock salt, partly filled with gases, which ran parallel to the stratification and could be traced over approx. 12 m on strike and approx. 20 m in collapse. The finely furrowed surface of the rock salt layer and its structure characterized it as a sliding surface. The dip of this slide was 75-80 degrees to the east. This gap was even more evident in the 600 m level. Sliding surfaces without crevices were found at other points in the mine outcrops, e.g. B. between mining 4 and 5 in the 584 m level and also at the northern end of the mining field on the border with the surrounding rock salt. The main faults run partially into the overburden, but are cut off and protected against the surface water by cement or the recompressed clay.

In the area of ​​the "Friedrich Franz" -schacht "Lübheen" the salt dome flanks are relatively steep to vertical; in the south-western edge area they also tip over. After GEINITZ , this is followed by a second saline pressing zone in continuation of the salt structure. In the immediate vicinity of the shaft, the gypsum hat appeared as insignificant flat top exposed, the so-called "Gipsberg".

The following sequence of layers was encountered in the bores and pits:

  • Zechstein 3 (Z 3, Leine series):
Main anhydrite (gypsum and anhydrite, above partly with dolomite and clay, A 3); 200 m thick.
Gray salt tone (T 3); 3 m powerful
  • Zechstein 2 (Z 2, Staßfurt series):
Red rock salt with kieserite and boracite (capstone salt , Na 2r), 1.5 m thick.
Staßfurt potash seam (K 2, hanging group; white carnallite, 20-25% KCl), 28 m thick.
Rock salt intermediate, consisting of gray rock salt (5 m thick); a so-called "black stripe" (0.05 m thick); reddish rock salt (2.5 m thick).
Staßfurt potash seam (K 2, lying group; reddish carnallite, 14–17% KCl), 8 m thick.
Staßfurt rock salt Na 2.

The cross passage 2 met at the 500 m level in the south pit box, two hard salt strands in close proximity to the red salt clay. The hard salt has 18–35% KCl, on average 20% K 2 O. According to Richter , it is to be regarded as local potassium salt storage.

The Conow salt dome measures around 21.125 km 2 at a depth of 500 meters . The flanks of the salt dome are formed quite differently. The age of formation of this saline structure should coincide with that of the Lübenheen-Jessenitz salt dome. The salt level is −115 m above sea ​​level .

Approximate location of the Conow salt dome, the potash works and the Conow salt works

To the northeast, this Evaporitdiapir shows the flankest slope (about 20 degrees to 900 meters depth), further to the northwest the slope increases. The north-west to south-west flank area shows a flank overhang, then to the south-east there is a vertical flank position up to about 500 m depth, which then decreases to about 45 degrees. In the event of a general collapse of the salt dome in the NE-SSW direction, an ESE-WNW strike can be detected .

Quaternary and tertiary layers form the hanging wall of the salt dome. The Quaternary is on average 25–30 m thick and consists of alternating layers of yellow till and gray till with yellow sand. The Tertiary above the salt dome varies in thickness between 25 and 80 m. Black-gray, mica-containing clay and sand, which are probably attributable to the Miocene , as well as black, fat clays are represented . In particular it is Septarian clay , as well as glauconite and mica-containing sands from the Upper to Lower Oligocene . The salt-bearing layers found in the boreholes and pits are to be assigned to the upper Zechstein series. The following layer sequences of the Zechstein could be determined:

  • Leine series: Zechstein 3: with clay medium salt, steam salt, anhydrite medium salt, orange salt , line salt and the main anhydrite.
  • Staßfurt series: Zechstein 2: with the Staßfurt potash salt seam and the Staßfurt rock salt, respectively. the hard salt camps A and B and the carnallite camp C.

Through the boreholes Conow I to IV (borehole profiles see PDF file on the right) and the shaft, the main anhydrite, which has been converted into a gypsum cap in its upper part and which is strongly fissured, was first exposed. Its upper edge is −5 m above sea level , towards the flanks it drops sharply. Anhydrite and gypsum extend to the salt level above the salt dome at −114 m above sea level; its thickness averages 110 m.

FULDA reports that the Ronneberg and Riedel seams of the linen series have not been identified anywhere. When driving the main crosscuts, narrow potash layers were occasionally driven through. These could be the rolled-out remnants of these seams.

There is no geological information available about the part of the salt dome that overlays the southern section of the 480 m level from about blind shaft II. Due to the risk of caustic ingress in the upper salt dome, it was certainly decided not to drive an investigation cross-cut from the filling point of the 380 m level to the south. The saline developed by the mine works has the strike direction OSE to WNW when it is almost vertical.

Between the individual strands of the potash store, younger and older rock salt occurs in colorful alternation. The steep stratification, the bends and upsets, the crushing, sliding surfaces, crevices, gas and lye inclusions are evidence of the strong tectonic movements to which the salt dome was exposed when it climbed up cracks .

Representation of the strong alternation of steep saline layers in the Conow potash works

The thickness of the potassium salt layers varies from thin, rolled out strings with a thickness of a few centimeters to dams of approximately 55 m in thickness.

The most important potash deposits are:

  • The bearing A is composed of hard salt from an average of 13 to 15% K 2 O with a thickness of 20 m; Langbeinit occurs in places on the lying surface .
  • The bearing B includes hard salt from an average of 13 to 15% K 2 O, to the west, it gradually goes into carnallite above. It reaches a thickness of 4 to 10 m.
  • The support C has Brekzienstruktur , is 4 to 15 m thick and leads carnallite 9-10% K 2 O. It goes up to between the 530- and 480-m level in kainite over. In places it also has kieserite . The original stratification of this kieseritic carnallitite is often well preserved near the host rock, otherwise it is blurred by breccia formation.

At a distance of around 500 m southeast of the shaft, the warehouse turns; it has been compressed here and widens to a carnallitic dam of 55 m thickness. One strand runs from the bend to the west about 400 m into the younger rock salt. Pure white carnallite occurs at the bend, presumably a metamorphic result of the tectonic processes . Up to this bend in camp C, the entire part of the pit opened to the south faces an anhydrite wedge up to 75 m thick. It must already be anhydrite from the salt dome flank. The correctness of this assumption is confirmed by a comparison of the salt dome boundary line marked in this way (see figure above left) with the result of the seismic reflection studies from 1969.

The hydrogeological conditions

The valley sand area between Sude and Rögnitz is generally rich in water. The groundwater level of the Lübenheen-Jessenitz salt dome - in the area of ​​the Jessenitz shaft - is about 5 m below the ground; the direction of flow of the groundwater is generally west to southwest. The cavernous to fissured leaching area above the salt structure, the so-called gypsum hat or caprock, is highly saltwater-bearing from a depth of around 150 m. The water inflow during the lowering of the shaft sometimes exceeded 40 m 3 per minute and, as described below, caused considerable sinking difficulties.

In the area of ​​the "Friedrich-Franz-Schacht" the water level is about 1.0 to 3.5 m below the ground. In the immediate area of ​​the shaft itself, the highest measured groundwater level was −14 m above sea level. A groundwater divide runs about 100 m north of the shaft in an east-west direction. Accordingly, the direction of groundwater flow in the shaft area is approximately SSW. Increased chloride contents reveal the correspondence to leaching solutions in the deeper subsurface. There is also strong salt water flow in the gypsum hat. In 1896, the inflows in the gypsum quarry at a depth of 12 m were 27 m 3 / min with a salt content of around 45 g / l. Even at a depth of 224 m, a completely “uncut” gap was encountered in the gypsum, which, due to its enormous salt water flow , required considerable secondary sealing work in the cuvelage of the shaft lining until January 1908. Open fissures leading to salt solutions in an approximately 3 m thick Langbeinitic-Sylvinitic transition layer in the lying area of ​​the potash store on the 430-m level ultimately led to the drowning of this mine.

The hydrogeological conditions in the area of ​​the Pleistocene sediments of the Conow salt dome were examined by Wehring . The investigation area comprised around 7 km 2 between Grebs and Conow. The hydrogeological conditions are characterized by the location in the top area of ​​the Conow salt dome. The collapse of the structural apex - Geinitz even assumes postglacial movements - resulted in extensive fault zones. For example, the Pleistocene and Miocene sands are directly adjacent to one another.

The loose sediments overlying the salt dome are divided into three relatively powerful aquifers by cohesive intermediate deposits (boulder clay and marl, septarian clay ). They are related to each other. Approximately in the top area of the salt dome, near the shaft - the exact course could not be proved beyond doubt to date - runs east-west a basic watershed .

The gypsum hat leads to salty water on countless crevices and crevices filled with gravel and sand. It cannot be predicted to what extent this water will run off over the flanks of the salt dome. One thing is certain - proven by the existing connection between the groundwater and the gypsum hat waters and the presence of the brine source southwest of Conow - that such a process must take place, which ultimately leads to a continuous drop in the salt level.

The lye problem in salt mining in southwest Mecklenburg

The drowning of the Jessenitz mine

The access area of ​​the solutions or water that led to the drowning of the mine building

As early as 1902, a leaching point was found on the 542 m level, in a steeply upright carnallite layer located around 150 meters north of the shaft, in the horizontal section of the backfill section leading to mining 5 north. The added solutions were saturated; their amount was a few liters per minute. At other points in the same stratigraphic area between the 542 and 584 m levels, more or less saturated salt solutions emerged. Some of these dried up after a short time.

Further caustic inflows were noticed from 1906 in quarry 3a of the 584 m level (inflows: November 1906: 3 l / min; June 1908: 3 l / min; March 1911: 6 l / min) and from 1910 also in quarry 2 north the 576 m level (inflows: December 1910: 1 l / min; January 1911: 2 l / min;). At the beginning of June 1912, a sudden sharp increase in the filling of the lye on the 542 m level was noticed. "In the first days of June 1912, the flow rates were around 60 liters per minute, slowly increasing to around 450 liters per minute by June 9, then falling back to 150 to 200 liters per minute for a few days and increasing on June 13th again to approx. 360 to 450 liters per minute; when the measurements were resumed on June 23, there was an inflow of approx. 2000 liters per minute, which continued to increase on June 24th so that the mine workings and the shaft was completely flooded on June 24th and 25th ".

These solution inflows flowed through the backfill section into mine 5 north, which had not yet been completely backfilled to the roof, and through this, flushing away part of the sand backfill, through Bremsberg 1 north to the 604 m level (see table on the right). Most of these salt solutions were pumped into trucks and brought to the surface. The smaller part eventually flowed over the 676 m level and specially laid pipelines to the 700 m level, so that it could also be brought to the surface from here by trolley.

date Density in ° Bé KCl NaCl MgCl 2 Cl SO 3
June 1, 1912 31.25 6.1% 6.2% 26.7% 24.1% 2.7%
June 8, 1912 29.50 9.1% 11.9% 17.1% 22.4% 2.0%
June 10, 1912 29.50 9.9% 12.5% 15.9% 22.4% 2.0%
June 13, 1912 28.75 11.2% 15.7% 11.5% 21.8% 1.7%
June 23, 1912 28.25 11.9% 22.3% 4.2% 21.5% 0.8%
June 24, 1912 28.00 11.8% 22.1% 4.4% 21.5% 0.8%

Along with these increased inflows, crackling noises were also noticed in the area between the 542 and 600 m levels. Later, from around June 5, 1912, even thunder-like blows were registered in the mountains with subsequent crackling. The analysis of the solutions showed a steady decrease in the magnesium chloride content from around 350.57 g / l at the beginning to only 56.32 g / l with an increase in the sodium chloride content from 81.41 g / l to around 282.88 g / l. The origin of these solutions from the leaching area of ​​the salt dome was thus proven beyond doubt. This was also confirmed by observations of the water levels in the surrounding waters ( Probst Jesar See , Großer Sarm) and the wells. The management realized that the inflows could not be controlled in the long run and decided to abandon the mine building below 500 m. From here on, the shaft was intact and dry, and mining was to be continued from here. But this hope was not fulfilled.

Operations manager Kulle noted in a letter to the mining authority on June 17, 1912: "Regarding the above, it should also be noted that on the afternoon of 13th of the month at around 4 o'clock a particularly violent thunder-like thunder was heard in the pit, followed by a persistent crackling and that such blows were then repeated at intervals of 10 minutes until the last people left the pit around 6:00 pm These blows were made within the entire mine building between the 600 and 500 m level by all the people present there detected".

On the afternoon of June 24, 1912, the inflows increased so much that the entire mine was drowned within a few hours. "Officials who were retracted on June 24 in the morning, found by 11 00 construction still dry, the tributaries not more, on the 700-m level 60 cm water level. 3/4 1 located at the filling of 600 m level Suddenly their lamps were extinguished by a strong air current and they noticed water flowing out from the north and south at great speed, which hit around the shaft and crashed into the about 10 m distant Jeseníky. On the morning of the 25th, the water was in shaft 41 m underground. Here it rose up to the 29th to 35 m, and then on 19 July it fell to the height of 38 m, at which it remained (apart from a small fluctuation) until mid-August ".

The drowning of the Lübenheen mine

As early as 1905, several leaching points were approached on the 430 m level set in a north-easterly direction - already starting in the shaft break. These were bound to a porous Langbeinitic-Sylvinitic transition layer from the Staßfurt rock salt (Na 2) to the Staßfurt potash seam (K 2) approx. 4 m below the lower potash deposit. According to the location of the driveways and the dam gate, the backfill of this lye horizon must have been far more productive to the north than in the same stratigraphic area near the shaft, otherwise one would certainly have waived further driving this route from the outset or the lye site would have been closed with a 13th -m wall dam was not necessary (see illustration on the right). The following figures can be found in the archived mining authority files about the quantities and chemistry of the added solutions: (see table below; data in percent by mass):

date MgCl 2 MgSO 4 KCl NaCl Bulk
May 6, 1907 32 5 0.2 0 0.8 l / min
June 7, 1907 24 8th 5.8 4.9 no information
July 3, 1907 21st 10 1.7 6.9 no information
August 9, 1907 15th 12 3.8 10.4 Continuous increase before the dam closes
September 28, 1907 13 12 4.8 10.8 dito
4th October 1907 8th 12.8 6.6 11.0 75 l / min
October 7, 1907 5.7 13.8 6.8 16.2 no information
October 25, 1907 4.7 12.5 7.0 26.4 no information

In the operational plan for 1910, a leaching point in the eastern section of the filling location of the 430 m level, only 2 m away from the shaft, is reported: "At the southern end of the route in the rock salt, a steep, approximately 30 cm wide chasm was approached, the one with lye was filled and the caustic was allowed to flow out for a long time without any noticeable pressure. When the curved uphill section was driven up from the western filling site soon afterwards, a similarly steep caustic gap of 60 cm width was created with this in the same rock salt layer, also on the southern face Otherwise there were numerous smaller fissures and pores next to it, which crossed over the roof and floor to the northern section. In the lye of the large fissure, muddy kieserite and large rock salt crystals were found. The lye initially flowed in considerable quantities without any noticeable pressure off, then soon subsided, but remained constantly flowing ".

date MgCl 2 MgSO 4 KCl NaCl
1905-1912 31-32% 4-6% 2-3% 0.8-3%
1913-1915 29-32% 5-6% 3–5% 0.8-3%

Other lye sites in the mine were always tied to the same stratigraphic horizon. So at a depth of 430 m in the shaft tube (see illustration "Seigerrissliche representation of the location of the lye inflow point at the shaft" Friedrich-Franz "Lübenheen", top right). The gaps encountered here were up to 10 cm wide. At this point, the shaft wall was continuously leaking. In addition, the leaching point in the south-west of the shaft at a depth of 446 m should also be mentioned. Here the inflows were initially 1–1.2 l / min; but later they went back completely. The area was later walled up.

Ultimately, even caustic was found in the same horizon on the western face of the 600 m level driven to the northeast (about 5 liters in several weeks. Composition: 36% MgCl 2 ; 3% MgSO 4 ; 2% KCL; 1% NaCl). From 1905 to 1912, the inflows to the leaching site in the shaft break section of the 430 m level were 0.3–0.5 l / min and saturation values ​​averaged 31–32% MgCl 2 ; 4-6% MgSO 4 ; 2-3% KCL; 0.8-3% NaCl relatively constant (see adjacent table):

After inspecting the mine and daytime facilities on June 29, 1912, Bergrat Prof. Dr. Tübben :

"1. Relocation of the mining limit from 430 m to 463 m underground. 2. Reinforcement of the shaft safety pillars from 50 m to 100 m radius. 3. Offset of rock salt mining northeast of the shaft and possible restriction of future rock salt mining to the west of the shaft Mine workings. 4. Dense offset of mine workings I and II above the 430 m level up to the roof. 5. Increased regular inspection of the shaft construction ".

These measures also led to a temporary calming of the inflow activities. Up to May 1915 only about 0.16 l / min had been registered. In June 1915 they rose to 0.4 l / min; however, in December of the same year they were already 2.7 l / min. The MgCl 2 content decreased from an average of 29% previously to 18-19%. Instead, the MgSO 4 content rose from an average of 5–6% to over 9%, the KCl from an average of 3–5% to 8% and the NaCl from an average of 1–3% to 4–7%. The density remained almost constant at 1.30 g / ml.

To combat the tributaries, boreholes were driven into the fracture zones and magnesia cement was injected. Extensive clinker insulation was also installed in the shaft break and the surrounding areas. But the pending solutions made their way around this and ultimately emerged through the carnallitite lying in the shaft. An attempt was now made to contain and dam the tributaries above the 430 m level by creating a 418 m auxiliary level. For this purpose, a high fracture was struck on the 430 m level. On June 5, 1916, the main rift was also reached. At first 6 l / min, later 109 l / min inflows were registered. On June 11, 1916, the first dam was completed. According to a report by the mining authority, however, it had leaked on August 8, 1916 at a pressure of 25 bar; 10-12 l / min of saline solution flowed in. More dams were built, the last one made of oak. The inflows were 170 l / min on August 26, 1916 and 235-250 l / min on September 17, 1916. As a result of the throttling of the inflows on the 418-m auxiliary level, the inflows on the 430-m vertical section increased.

In an addendum to the operations plan dated October 3, 1916, the management decided to pull the segment lining down from 394.84 m to 480 m; later even possibly below the 500 m level. However, the caustic leakage in the shaft tube at a depth of 430 m gave rise to fear that the shaft walls would be washed away, so that the mining authorities ordered that the 500 and 600 m levels be abandoned. From October 14, 1916 - in addition to extensive lye control work - only the 430 m level was used. The inflows were up to 700 l / min. In a further supplement to the operating plan dated October 12, 1916, the management finally requested: "The shaft will be exposed from a depth of 430–600 m and above it will be closed to prevent the ingress of water. For this purpose, a concrete block from 410–390 m will be inserted that reaches into the base of the segmental lining. A standpipe with a tap is inserted into the concrete block ". A filling site was then to be set up at 370 m depth in the carnallite and the deposit was to be redeveloped in a western direction.

A letter from Oberbergrates Duszinski to Bergrat Tübben dated November 4, 1916, indicates that Tübben was still hoping that the salt solutions that were added would be highly saturated. Because here it says: "You assume that the lye will only fill up the burrows gradually and hope that this will not make the lye noticeably sweeter. You base this hope on the fact that until the end of the analyzes, the incoming lye was completely saturated of rock salt and the gypsum mountains must contain enormous amounts of salt water, since for years all the kieserite wash water from the chemical factory, which is high in sodium chloride, was directed into the gypsum quarry, where it disappeared ".

On November 25, 1916, the mining authority was informed that several meters of the concrete block had already been placed from 410 m upwards. The lye on the lower levels increases slowly and has not yet reached the 500 m level (inflows on December 3, 1916 approx. 3 m 3 / min). The total void volume of the Friedrich Franz mine at that time was around 320 Tm 3 .

On the night of December 8th to 9th, 1916 (between 10 p.m. and 3 a.m.), strong underground noises were heard in the town of Lübenheen and the surrounding area. At 1 o'clock a single very strong tremor was registered with a sharp cracking sound. The water level in the shaft was plumbed on December 9, 1916 at 9:30 a.m. at 200 m and at 11 a.m. at 50 m.

In addition to ground movements, the sinking of the groundwater to 2 m was also observed. The water level in the lake in Probst Jesar, about 1.5 km away (caused by a sinkhole) sank by about 10 cm. The ground movements at the Friedrich-Franz-Schacht occurred mainly where such had already occurred in July 1912 when the neighboring Herzog-Regent Jessenitz mine was drunk. B. over the former gypsum break and on its edges. The depth of these small sinkholes was about 2 m. Damage to the building was registered at the colliery house, the salt mill, the hoisting machine and the boiler house. In the village of Probst Jesar, sinkholes also occurred, for example on the western edge of the lake. In some corridors numerous small and occasionally strong cracks formed, which mainly ran in an east-west direction. The houses of the citizens Burmeister and Prosch were badly damaged .

When the mining authority visited the shaft area on December 14, 1916, the cage could be lowered unhindered to the 25 m thick concrete block, so that its location appeared unchanged. It was initially assumed that the shaft was drowned by leaks in the tubbing column as a result of damage or destruction of the same or of the lowest picotage joint above the concrete block. Later - at a meeting of the distribution office for the potash industry on December 19, 1916 - the works administration stated that the water ingress was caused by the bursting of the salt mountains between the bottom of the rift and the shaft. Due to these rock movements, the lowest part of the shaft collapsed. For these reasons, the swamping of the mine was rejected as hopeless. The author of this article considers it to be just as likely that the suddenly increased inflows emerged from the area of ​​the stratigraphically identical point on the shaft at depth 430 m, which has been known for a long time, i.e. directly at the filling point of the first level.

The lye access in the Conow mine field

About 45 m from the main shaft, in the striking stretch I to the west, 380 m level, a first inflow of caustic was noticed on October 13, 1913 (initially 0.2 liters per hour; later about 4.5 liters per day). Based on the experience gained during the operation of the neighboring potash works in Lübenheen , the dismantling of this sylvinite deposit was refrained from because of the further caustic inflows to be expected in the wall.

Further archived information about liquor inflows date back to 1915 (October 8, 1915: Level II, northern cross passage).

As is further reported here, on February 23, 1916, in a horizontal borehole to explore the deposit (level III, borehole to the south) at a final depth of 239.4 m in the anhydrite, a liquor inflow was detected. Twelve bags of cement were pressed in to seal it.

The appearance of caustic in an investigation section in the south-east field of the 580 m level in 1924 prompted the mine administration to immediately stop any blasting work in this area. This affected dismantling works 7, 9 and 11. Damming measures were prepared ( wall dam ), but not completed after the lye inflow had decreased. "Since the lye leakage on December 21, 1924 was only 0.03-0.06 l / h, the dam only needs to be built up to about 3/4 m high".

The archive records show a total of 23 such caustic deposits within the mine, 10 from horizontal boreholes alone. Some of the pourings were substantial. Since the discharge characteristics and information on the chemistry of these liquor inflows are mostly missing, their origin cannot be proven beyond doubt. A large part were certainly so-called "residual and remelting liquors". They are of no interest for a further assessment of the long-term safety of the mine.

All leaching points in the Conower pit structures are listed below:

Serial No. Operating point Mountains Inflow time Discharge volume; Lye analysis
(l / d = liters per day; l / h = liters per hour) 		Remarks   
1 Manhole Transition zone between gypsum and rock salt, depth 143.5 to 166.5 m Around 1919 to 1922 (sealing work until December 14, 1922) Inflows drop by drop, no splash; Quantities are missing. Analysis data is missing; Density about 1.2 g / cm 3 Sintering crash on March 9, 1922. Elimination of the tributaries by injecting approx. 25 t of magnesite behind the segments
2 Striking route I to the west, 380 m level Hard salt / sylvine October 13, 1913 to early 1914 October 13, 1913 = 4.5 l / d;
November 3, 1913 = 0.9 l / d;
November 9, 1913 = 0.8 l / d;
November 28, 1913 = 0.5 l / d.
Lye analysis is missing		 no
3 Test section to the south, 580 m level, horizontal drilling to the south 234.80 to 235.80 m anhydrite; 235.80 to 238.30 m of black salt clay January 31 to February 24, 1916 Initially 432 l / d. Lye analysis is missing Sealed on February 24, 1916 by injecting 16 bags of cement.
4th Side location 1 to the east, 580 m level, horizontal drilling to the east 41.65 to 42.00 m rock salt, water-white; 42.00 to 42.15 m rock salt, dark, interspersed with anhydrite, 42.15 to 48.95 m anhydrite May 23-25, 1916 May 23, 1916 = 1730 l / d;
May 24, 1916 = 9180 l / d;
May 25, 1916 = 8230 l / d;
Lye analysis is missing		 Presumably sealed with cement on May 26, 1916
5 Eastern strike strike, 580 m level, horizontal well 2 to the south 261.80 to 271.30 m light younger rock salt with embedded inclined anhydrite cords January 16, 1917 to March 1917 January 16, 1917 = 0.1 l / d;
March 15, 1917 = 0.1 l / d;
Lye analysis missing,
density 1.288 g / cm 3 ; MgCl 2 25.8%		 no
6th Hard salt mining II to the east, 580 m level Coarsely crystalline rock salt, blue in places, with traces of carnallite and salt clay deposits January 4, 1919 to? Quantities are missing; 1 m 2 "moist" area, no dripping. Completely dry from January 9, 1919 no
7th Eastern chamber at Blind Shaft I, 580 m level, horizontal drilling to the east 10.20 to 62.00 m anhydrite, 62.00 to 68.00 m salt clay, drill hole set at 269 m in rock salt January 10-16, 1919 A total of 500 liters of lye and 250 liters of thin magnesia cement; Lye analysis is missing When the borehole was backfilled with magnesia cement, the ingress of alkali was triggered, presumably in the anhydrite area
8th Shaft filling location 480 m level towards the northeast not specified, probably 2 old drill holes April 14 to June 1919 Western borehole: one sample tube in 36 hours; eastern borehole: one sample tube in 28 hours; Lye analysis is missing After removing a sinter crust, the lye inflow was evident; sealed with magnesia cement in July 1919
9 Camp A, dismantling 1 west, 706 m level Hard salt, at 50 m excavation length on the south face in a 4 m deep pilot hole May 10, 1919 -? Moisture in the borehole with crackling noise; Lye analysis is missing no
10 Shaft filling location 706 m level, horizontal drilling to the northeast 0 to 59.2 m rock salt, 59.2 to 60.9 m Rachel, 60.9 to 133.5 m rock salt with anhydrite July 18, 1919 to February 16, 1920 On July 18, 1919 = 1500 l / d, then until July 24, 1919 = 480 l / d, from July 25, 1919 dry. Since the middle of November 1919 greenish colored caustic has been released, amount about 16 l / d. December 5, 1919 = 17.2 l / d, December 8, 1919 = 12.5 l / d, December 9, 1919 = 11.9 l / d, thereafter continuously decreased to 6.8 l / d on the 16. February 1920; Lye analysis is missing Sudden leakage of the lye, bubbling noise, gas leakage. Sealed with magnesia cement on February 16, 1920
11 Chop to camp A, 706 m level Hard salt Jan 6, 1920 -? Little discharge; Lye analysis is missing Small amounts of caustic and gas were drilled in a borehole in the middle of the route
12 Parallel stretch to the west, 645 m level Rock salt Apr. 20, 1920 -? April 20, 1920 = 4-5 l / h, decreased to very small amounts after 1 h. Analysis: KCl = 2.15%; MgSO 4 = 1.2%; MgCl 2 = 38.95%; NaCl = 9.6%; Bromine = 4.73%; Density = 1.315 g / cm 3 At 18 m length on the western face at the 2nd hole in the bottom, first moisture, later increase to caustic outflow with hydrocarbon gas leakage (bubbling noise)
13 Parallel stretch to the west, 645 m level Carnallitite (?) August 1921 Quantities are missing; so-called "damp" spot, no dripping; Lye analysis is missing With a length of about 40 m there is a "damp" spot in the ridge
14th Mining 1 east, camp A, 706 m level, horizontal drilling to the north 0 to 1.2 m hard salt, 1.2 to 18.9 m rock salt, 18.9 to 19.5 m carnallite March 31, 1924 to January 9, 1925 Choppy / sporadic small bulk, then partly dry, partly 1 to 3 cm 3 / h. Definitely dry from June 1925. Quantities: April 1, 1924 = 0.504 l / h, April 10, 1924 = 0.284 l / h, April 22, 1924 = 0.146 l / h, April 30, 1924 = 0.050 l / h. Lye is said to have been fully saturated (entry from May 3, 1924); Density on June 17, 1924 at 0.132 l / h = 1.318 g / cm 3 no
15th Thickness crosscut to the south in the planned mining 13 east, camp C, 580 m level 0-0.5 m carnallite; 0.5–1.0 m carnallite with rock salt; 1.0–2.0 m rock salt From April 14, 1924 until the mine was closed April 15, 1924 = 0.018 l / h; April 17, 1924 = 0.026 l / h; April 24, 1924 = 0.020 l / h; April 30, 1924 = 0.016 l / h. Analysis: KCl 3-4%; CaCl 2 0.1-0.2%; MgCl 2 33-35%; NaCl 2-4%; Bromine 2-3.5 g / l; Lithium was detected by spectral analysis Cross passage length 10 m; Pre-drilled hole 1 m above floor level, 2 m deep; audible leakage of gas. This is lye point A 1 (see Fig .: lye points, following)
16 Cross passage from pillar 9/11 east, camp C, 580 m level Carnallite (transition to anhydrite) From March 31, 1924 until the mine was closed April 4, 1924 = 0.555 l / h; April 5, 1924 = 2.800 l / h; April 7, 1924 = 1.412 l / h; April 8, 1924 = 1.636 l / h; April 9, 1924 = 1.091 l / h; April 10, 1924 = 0.900 l / h; April 12, 1924 = 0.070 l / h; April 22, 1924 = 0.014 l / h; April 30, 1924 = 0.073 l / h.
8 analyzes from March 31 to March 8 April 1924: KCl increasing from 4.47% to 5.24%; MgSO 4 lanes; MgCl 2 decreasing from 28.33% to 27.96%; NaCl increasing from 7.81% to 7.96%; Bromine and lithium always detectable.		 The inflow was tapped at a crosscut length of around 16 m when drilling the cutoff; also leakage of nitrogen gas. On November 28, 1924, stronger gas leakage, nebulous. Until December 30, 1924, varying strength of gas leakage. Gas analysis: 5% oxygen, 11.3% hydrogen, 5.0% methane, 78.7% nitrogen. This is lye point A.
17th Strikethrough to the west, Camp C, 580 m level, horizontal well to the south 70.2–70.6 m of rock salt-wedged anhydrite, 70.6–80.1 m of light rock salt with kieserite and anhydrite strings, 80.1–82.0 m of compact anhydrite. At this depth the well was stopped in February 1924 From May 15, 1924 until the mine was closed From 15.-22. May 1925 = 0.002 l / h; Lye analyzes are missing none, that is lye point A 2 , a so-called "dripping" with the same chemical parameters as under item no. 15
18th Camp B west wing, 580 m level, horizontal drilling to the west 0–180 m white rock salt August 1st to 30th, 1924 Total discharge 0.21 l; then a few drops a day; Lye analyzes are missing no
19th Cable car route at Blindschacht II, 580 m level, horizontal drilling to the north 0–62.3 m rock salt, 62.3–64.4 m salt clay, 64.4–72.0 m anhydrite November 4, 1924 to October 1925 Approximately 0.2 l in 10 days; October 1925 a total of approx. 0.8 l; Lye analyzes are missing no
20th Trying to the east, Camp A, 480 m level, horizontal well at the end of the line to the south 14.3–21.0 m anhydrite with rock salt, 27.0–32.9 m carnallite, set after several hard salt and kainite sequences at 85.0 m in light rock salt February 2, 1925 to September 1925 In one month about 0.2 l of dropping liquor; Lye analyzes are missing A horizontal well that has existed for years and was absolutely dry up until then
21st Mine 11, Camp C, 580 m level, on the southern face Carnallite April 28, 1925 to January 1926 From April 28th to April 27th May 1925 about 0.2 l; October 9–24. November 1925 about 0.290 L; Lye analyzes are missing none, that's lye point A 3
22nd Cross passage to Bergemühle , partial level A, 645 m level, left joint with a length of 7.0 m Rock salt June 3, 1925 – October 1925 In one month about 0.2 l of dropping liquor; Lye analyzes are missing Exit at the freshly shot stroke
23 Main cross passage to the south, 580 m level, 54 m south of the main shaft, eastern face at 3.60 m length Rock salt with traces of carnallite From November 24, 1925 until the mine was closed On November 26, 1925 = 0.240 l / d; November 27, 1925 = 0.480 l / d; November 28, 1925 = 0.450 l / d; November 29, 1925 = 0.240 l / d; November 30, 1925 = 0.240 l / d; Analyzes from 26.-30. November 1925: KCl decreasing from 0.40% to 0.21%; MgSO 4 increasing from 1.32% to 1.68%; CaCl 2 not detectable or traces; MgCl 2 decreasing from 44.85% to 44.27%; NaCl increasing from 0.00% to 2.32%; Bromine increased from 7.22% to 8.88%. Specific weight increasing from 1.350 to 1.353 g / cm 3 Numerous drip points; discovered on November 24, 1925 after a two-day break in operation

In contrast, the caustic leakage from a horizontal borehole in the test section to the south of the 480 m level is more significant (striking section to the east, camp A, 480 m level, horizontal borehole at the end of the section in a southerly direction; No. 20 in the table below) . This borehole penetrated a carnallite deposit of 5.9 m in thickness, which presumably swung to the south in the further course. In front of this carnallite deposit, anhydrite, interspersed with rock salt, was drilled at a depth of 14.3 m. This previously unfilled borehole was dry for almost 10 years until caustic suddenly emerged.

It is likely that this inflow was triggered by rock mechanical effects of the C.3.0st and C.4.0st mines and especially of the entire south-eastern construction site of the 580 m level below. It is obviously the same anhydrite layer in which the caustic spots A, A 1 and A 2 (compare in the table above) occur. Investigations by Erda-AG, Institute for Applied Geophysics Göttingen in December 1924 established a connection to the salt water of the gypsum hat from the latter lye sites. The detection of CaCl 2 in the alkalis confirmed the correctness of the geophysical investigation results. After the occurrence of these caustic inflows, all further extraction work in the south-eastern construction field of the 580 m level was immediately prohibited by the mining authority.

This diary entry by the last operator Erwin von Boremski is to be assessed even more critically : "On 24.XI.25, after two days of shutdown, immediately after entering the main cross passage to the south, 3rd level, 54 m south of the shaft at the eastern line joint Noticed a drip. The lye escapes in many small places with a width of 3.60 m as a damp misting of the joint. No moisture is noticeable on the ridge of the route. A groove was hacked into the joint 30 cm above the base and metal sheets attached by spreading with magnesite ". An analysis of the lye collected up to the next day showed full MgCl 2 saturation at a density of 1.350 g / cm 3 (240 cm 3 were collected in 18 hours ).

A note from the Mining Authority dated July 26, 1926 states: "The inflows did not cease until the mining operations were closed, but continue to exist in the same composition. In December 1925 (meaning the inflow described above on November 24th 1925) a new discharge occurred on the same floor at a different point, in a dangerous vicinity of the shaft. The undersigned authority is not responsible for declaring that since these circumstances occurred - the one that was the foundation of the mountain building of the Mecklenburg potash deposits was particularly hazardous seem to prove - there was no longer any hope of a long service life for the Conow potash works, that rather the likelihood of a worsening of the inflows and thus, as experience has shown that shut-off measures are not very successful, the mine workings were getting drowned ".

A report by the last operator of the Conow mine, Erwin von Boremski , to the state government of October 6, 1947, contradicts this opinion of the mining authorities : " All in all, it can be said that theoretically there are no significant obstacles to restarting the plant ". When assessing this view, it should be borne in mind that v. Boremski (who worked in the potash plant from 1913 until the mine was flooded; initially as a steiger, then as the manager in charge) was very experienced and of course knew how to assess the caustic situation and its prognosis . His report to the new state government is divided into " 1.) The shutdown of the Conow potash plant 2.) About the presumed condition of the mine workings 3.) About the possibility of restarting these plants 4.) About the productivity of the salt store" .

Bergrat Ernst Fulda , as the clerk at the Prussian Geological State Institute , dated August 14, 1936, submitted an extensive " report on the safety of the surface at the Friedrich Franz, Jessenitz and Conow potash works in Mecklenburg " for the Reich and Prussian ministers of economics in accordance with its decree dated August 4 , 1936 June 1936 _III 4588/36. In it he describes the salt dome of Lübenheen and the safety of the surface at the potash works Friedrich Franz, Jessenitz and Conow.

Discussion of the research results

One remark in advance: The following evaluation of the saline solution inflows and their pathways in the drowned or flooded with NaCl solutions potash and rock salt mines in Mecklenburg is based on the extensive archive material available and the accessible literature. However , it is not the intention of this Wikipedia article to draw conclusions from this for the assessment of the storage safety of contaminated substances in other salt structures in Germany. Such an assessment cannot be made across the board, but should be devoted to the specific individual case. However, it is now undisputed that the rededication of the original extraction mines to " custody mines " in the past has proven to be extremely problematic, if not dangerous.

A comparative consideration of the lye situation of the pits building on these salt domes is necessary, as both salt domes have approximately the same genesis and are only about 20 km apart. The former has risen to the surface of the day; its main anhydrite, which once covered it, is transformed into a caprock (gypsum hat). According to Geinitz , its flanks are almost vertical and all around show the same formation of both the saline and the dragged strata. The difference in altitude between the two salt levels is quite considerable at 125 m.

Conclusions on the occurrence of alkalis and water during the sinking and the excavation of the shafts “Herzog Regent” and “Friedrich Franz” on the one hand and the shaft “Conow” on the other hand, a connection with the ascent-related deformation of the saline deposits is significant. The system of crevices and cracks - the so-called Wegsamkeiten - within the Lübheen-Jessenitzer diapir , which extends to the surface, is much more pronounced than that of the Conower. In both cases, however, the tectonic disturbances are more pronounced the closer you get to the edge of these salt domes. Unfortunately, the existing seismic reflection does not provide any details on the formation of the flanks of the diapirs. The preferential flow paths of the alkalis and water are linked to fissures and faults and are not primarily found in the relatively brittle anhydrites and gypsum karst. The deformation and fracture processes also affect salt rocks that show a certain plasticity under pressure, such as B. rock salts, sylvinites and carnallitites. However, as soon as there are deposits such as clays and anhydrites in these layers, these too are inhomogeneous.

date inflow Caustic concentration
1905 0.16 l / min spec. Weight 1.3 g / cm 3 at 32% MgCl 2
1915 0.7 l / min 30% MgCl 2
January 1916 2.5 l / min 18% MgCl 2
September 1916 250 l / min 1% MgCl 2 and 25-28% NaCl
4th October 1916 600 l / min not specified
December 8, 1916 Schacht drowned in one day not specified

Almost all the caustic inflows in the "Friedrich-Franz-Schacht" Lübenheen pit originate from one and the same geological horizon, a long-legged- sylvinite transition layer from the Staßfurt rock salt (Na 2) to the Staßfurt potash seam (K 2) about 4 m below the lower potash deposit. . This means that in saline layers that otherwise react to saline tectonics in a plastic-plastic manner, pathways can develop through salt transformation processes. These pathways widening to the salt level or the groundwater were and could no longer be dammed up today. The physico-chemical / hydro-geochemical development of the liquor inflow into the mine building Lübenheen, which ultimately leads to drinking, shows the "classic" picture of a constant decrease in the MgCl 2 content with an increase in the NaCl content and of course the inflow (see table on the right).

In the pit field of the Jessenitz mine, a leaching site was found as early as 1902 in a steeply upright carnallite layer (on the 542 m level). The added solutions were initially saturated. Baumert documented their amount in 1902 as dripping liquor with an MgCl 2 content of 26.7%. In 1911 the flow was already 11 l / min; in May 1912 it was 45 l / min, on June 9, 1912 it was 10 times as much when the MgCl 2 content decreased to 15.9%. On June 13, 1912 the inflow was up to 250 l / min (MgCl 2 content sank to 11.5%), on June 23, 1912 it was 2000 l / min (MgCl 2 content 4.2%). The next day the pit was drowned within a few hours; the water level in the shaft leveled itself at a depth of 36 m. “The reasons that led to the destruction of both works are evidently the dangers of the mighty gypsum hat, which is heavily water-bearing, and which were increased by the lengthy and difficult shaft construction work, combined with a salt surface that was worn down by extensive swamping work. The fact that there was a connection between the water-bearing layers in the gypsum cap and the groundwater level is evident from the fact that after the drinking of Jessenitz the level of the approximately 1½ km² lake in Probst-Jesar fell by 30 cm and was different and strong Tremors occurred ".

Wolf comes to the statement in investigations into subrosion in the urban area of ​​Staßfurt that “... a large part of the faults responsible for deformation and fracture [will] be found in the anhydrite and gypsum karst. Increased or even only triggered by mining and the extensive dewatering measures associated with it, there may be locally strongly varying flow velocities, which can result in severe partial subrosion of the soluble material and local destabilization of the gypsum karst ”.

The CaCl 2 content found in some salt solutions has also been reassessed in recent years. "Contrary to earlier assumptions (e.g. Baumert , 1928) it was possible to prove that CaCl 2 is formed even within the evaporite layers at temperatures below 100 ° C through the reaction of concentrated MgCl 2 solutions with CaCO 3 compounds ... CaCl occurring in salt deposits 2 -containing solutions are therefore not a clear indication of an origin of the CaCl 2 component from the neighboring rocks of the evaporites, which excludes all other possibilities .

date Spec. Weight

(g / ml)

KCl

(Dimensions-%)

MgSO 4

(Dimensions-%)

CaCl 2

(Dimensions-%)

MgCl 2

(Dimensions-%)

NaCl

(Dimensions-%)

bromine

(Dimensions-%)

November 26, 1925 1,350 0.40 1.32 nn 44.85 nn 7.22
November 27, 1925 1,350 0.32 1.38 nn 44.84 1.8 7.06
November 28, 1925 1,350 0.32 1.44 nn 45.12 0.83 7.85
November 29, 1925 1.355 0.19 1.50 traces 44.40 1.17 7.22
November 30, 1925 1.353 0.21 1.68 nn 44.27 2.32 8.88

An almost "classic" residual caustic solution (also referred to as a relict solution) is the salt solution which entered the mine building of the Conow mine - in the main cross passage to the south, near the shaft on the 580 m level (see table opposite). The assessment of their genesis is based on their very high bromine content. "The geochemically most important minor or trace component of the chloride minerals and the saline solutions is the bromine or bromide from the seawater. During evaporation, Br accumulates in the concentrated seawater solutions, since the distribution factors bBr = Br mineral / Br solution for everyone Chloride compounds are <1. The genesis of the salt solutions is assessed by means of the absolute Br content ". What is also interesting about this lye composition is that no CaCl 2 was detected, which otherwise predominantly represents the indicator for an existing path to Caprock.

Except for two of the archived lye analyzes (lye sites No. 15 and 16 in the Conow plant) of the salt solutions that entered the three Mecklenburg salt works, there is no information on the lithium content . The solution analysis of this element is used today under certain premises also for the genetic and thus risk relevance of the caustic access .

Finally, the lye inflow described in more detail above in the main cross passage of the Conow mine on the 580 m level, only 54 m south of the shaft on the eastern section joint, should be discussed. This inflow suddenly appeared on November 24, 1925, years after this stretch of road was excavated. The lye emerged in many small places in a width of 3.60 m as a damp fogging of the joint. The responsible Grand Ducal Mecklenburg Mining Authority in Hagenow was very pessimistic about further operational safety in a note dated July 26, 1926. In contrast , the last operator of the Conow mine, Boremski , saw in a report to the state government of October 6, 1947, no reason to restart the potash plant after it had been swamped.

literature

  • Bruno Baumert: The lye storage in the layers of the Zechstein and their dangers for the salt mining . Journal of the German Geological Society, Volume 105, pp. 729–733, Berlin 1953.
  • J. Bodenstein, P. Sitz, N. Handke, H. Rauche: Concepts for the safekeeping of old mining shafts in water-soluble mountains . In: Meier, Srok, Löbel, Klapperich, Tondera, Busch, Wagner, Ranjbar (eds.): Lecture volume for the 4th Altbergbau-Kolloquium . Montan University Leoben, 4th-6th November 2004, Verlag Glückauf, Essen 2004.
  • H. Borchert: The salt deposits of the German Zechstein. A contribution to the formation of oceanic salt deposits . Archive for reservoir research. H. 67, Reich Office for Soil Research, Berlin 1940.
  • O. Braitsch: Origin and stock of the salt deposits . Springer Verlag Berlin, Göttingen, Heidelberg 1962.
  • Börger: Lye currents in drowned potash mines as the cause of later surface damage . Journal Kali, related salts and petroleum, issue 9, 1943, pp. 160-162.
  • Brinckmeier: To combat the risk of lye ingress in salt mines . Journal for Extraction, Processing and Utilization of Potash Salts ", Issue 9, 1925, pp. 138-141.
  • V. Ebeling: The sinking, drowning and rebuilding of shaft III of the Hansa potash works in Empelde . Kali und Steinsalz magazine, issue 4, 1954.
  • D. Eckart: Results of investigations into damage to decommissioned mining facilities . Freiberg research booklet A 526, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig 1973.
  • Ernst Fulda: On the origin of the German Zechstein salts . Journal of the German Geological Society Volume 75, Berlin 1923, pp. 1-13.
  • Ernst Fulda: Handbook of the comparative stratigraphy of Germany, Zechstein . Borntraeger publishing house, Berlin 1935.
  • Ernst Fulda: Decomposition of the carnallite rock in drowned mine rooms . Journal Kali, related salts and petroleum, Issue 11, 1943, pp. 201-204.
  • Enst Fulda: Report on the salt deposit of the Conow potash plant near Conow (Mecklbg.), Which has been registered for closure . Prussian Geological State Institute, Berlin 1926.
  • Eugen Geinitz: Geological observations during the water ingress in Jessenitz . Messages from the Grand Ducal Mecklenburg Geological State Institute, XVII, Rostock 1912.
  • G. Herrmann, U. Siewers, B. Harazim, E. Usdowski: Criteria for the assessment of salt solutions in the Zechstein vaporites of central and northern Germany . Potash and rock salt, 03/2003.
  • Gerhard Katzung (Hrsg.): Geology of Mecklenburg-Western Pomerania . E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2004
  • Ernst Loock: Disused shafts - a problem for the potash industry . Freiberg research booklet A 136, Akademie-Verlag, Berlin 1960.
  • Rudolf Meinhold: Comments on the question of the salt rise . Freiberg research notebooks C22, Akademie-Verlag, Berlin 1956.
  • Harald Meyer: Contribution to the research of the hydrological hazard [lye hazard] from the base layers of the Stassfurt series in the southern Harz potash district . VEB German publishing house for basic industry, Leipzig 1968.
  • Harald Meyer: On the problem of flooding and swamping potash pits . In: Neu Bergbautechnik, Issue 8, 1987.
  • Maenicke: Water ingress in potash mining . Kali magazine, Volume 12, No. 6, p. 11.
  • Günter Pinzke: Retrospective on inflows of water and salt solutions into the mine workings of former Mecklenburg salt mines (NE Germany). In: Journal for Geological Sciences (Hrsg.): ZGW - Journal for the Geological Sciences . 43rd volume, issue 1/2, pages 105–127, 2015.
  • Günter Pinzke: Mining damage analysis of the potash and rock salt mine Conow . Expert opinion (unpublished), District Office for Geology at the Council of the District of Schwerin, Geology Department, 1975, archive of the Stralsund Mining Authority.
  • Günter Pinzke: Assessment of the stability of the mine workings of the potash and rock salt mine Conow and the expected effects during the injection of liquid pollutants by means of drilling into the mine building . Diploma thesis, Bergakademie Freiberg, Geotechnical and Mining Section, 1976, LUNG MV archive, inventory number GM-003.525.
  • Günter Pinzke: For the calculation of saline dissolution phenomena in carnallitite . In: Neue Bergbautechnik, Issue 1, 1987.
  • Ullrich: The water ingress into the shafts of the Jessenitz and Friedrich Franz potash works in Mecklenburg . Kali magazine, Volume 12, No. 6, 1918, pp. 90–95.
  • Werner Gimm , Gottfried Thomas: Mining process and caustic hazard in potash mining . Akademie-Verlag, Berlin 1959.
  • W. Sander: Quantitative description of the solution metamorphosis when water penetrates a mine in the Zechsteinsalinar . In: Kali und Steinsalz, No. 2, 1988.
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  • Ferdinand Trusheim: About Halokinesis and its significance for the structural development of Northern Germany . Journal of the German Geological Society, Hanover 1957.
  • Martin Heinz Wolf: Visualization and quantification of the fluid dynamics in drill cores from the saline and overburden of the Staßfurt area using positron emission tomography . Dissertation, University of Leipzig, 2011.

Individual evidence

  1. ↑ Drowning . In: Meyers Großes Konversations-Lexikon from 1905. Online at www.zeno.org.
  2. ^ Author collective, series of publications by the State Office for the Environment, Nature Conservation and Geology Mecklenburg-Western Pomerania: Securing raw materials in Mecklenburg-Western Pomerania - inventory and perspectives -. (PDF; 3.3 MB) 2006, accessed on February 2, 2013 (issue 1).
  3. ↑ Karsten Obst: " Possibilities of underground storage for natural gas and CO 2 in northeast Germany ". Journal of Geological Sciences, Volume 36 (2008) Issue 4–5, Pages 281–302.
  4. ↑ Bruno Baumert: About caustic and water inflows in German potash mining . Dissertation from Aachen University of Technology, Gerstenberg Brothers, Hildesheim 1928.
  5. ↑ Wolf-Peter Kamlot, habilitation thesis, TU Bergakademie Freiberg: Mountain mechanical assessment of the geological barrier function of the main anhydrite in a salt mine. (PDF; 15.6 MB) April 2, 2009, accessed on January 13, 2013 .
  6. ↑ Katrin Hille, Göttingen: Atomic waste dump salt mine Asse II: Endangerment of the biosphere due to insufficient stability and drowning of the mine building. (PDF; 13.1 MB) March 1, 1979, accessed January 13, 2013 .
  7. ↑ Johannes Gerardi (Ed.): Staßfurt 2010 - Recognize, analyze, assess and forecast the future development of the damage caused by mining . EDDG excursion guide and publications of the German Society for Geosciences, issue 244.
  8. ^ Proposal 69: Zechstein Formations. (PDF; 21 kB) Accessed February 10, 2013 (1991 - 2011).
  9. ↑ Menning, M. et al .: Resolutions of the German Stratigraphic Commission 1991–2010 on Permian and Triassic of Central Europe . (PDF, online at edoc.gfz-potsdam.de; 2.3 MB) from November 16, 2012. Accessed February 10, 2013.
  10. ↑ Eugen Geinitz: On the geology of the Lübenheener mountain range I. and II . In: Archives of the Association of Friends of Natural History in Mecklenburg, Volume 65 (1911) and Volume 66 (1912), Schwerin State Library.
  11. ^ Richter: Geological pass of the southwest Mecklenburg potash salt deposits . Geological State Institute of the GDR, 1955, LUNG MV archive.
  12. ^ A b o. V .: Conow-Lübenheen results report . VEB Geophysik Leipzig, 1969.
  13. ↑ State Main Archive Schwerin, inventory signature 6.11-14, No. 3587/1, Ministry of Economics, Geological Passport of the Southwest Mecklenburg Potash Salt Deposits , set up by the Geological State Institute, Mecklenburg Branch, clerk Richter, Bergrat a. D., Rostock, January 1950.
  14. ^ Coordination Center for Nature and Environment eV (KNU), Friends of Nature Lower Saxony, Stephan Röhl: The emergence of the landscape . Online at www.naturschatz.org. Retrieved March 26, 2013.
  15. ^ W. Herde: Progressive and descendent processes in the sedimentation of the Riedel group (Zechstein 3). 1953, accessed February 5, 2013 .
  16. ↑ Ernst Fulda: Report on the salt deposit of the Conow potash plant near Conow (Mecklbg. ), Which has been registered for closure , Prussian Geological State Institute Berlin, 1926, pages 1-4.
  17. ↑ M. Wehring: Hydrogeological results report DE Grebs , VEB hydrogeology Nordhausen, 1974 Archive LUNG MV.
  18. ^ Eugen Geinitz: Geologie Mecklenburgs , Verlag von Carl Hinstorffs Hofbuchdruckerei, Rostock, 1922, page 167.
  19. ^ Acta regarding the former salt works near Conow, 1875 , inventory signature 5.12-5 / 1, Ministry of Finance, No. 2793, pages unnumbered.
  20. ↑ a b c d State Main Archive Schwerin, Mecklenburg-Schwerinsches Bergamt , inventory signature No. 5.12-3 / 18, No. 50: “Betr. the drowning of the Duke-Regent-Schacht of the Mecklenburg potash works and the consequences ”, files of the Großh. Mining Authority Lübenheen, sheet 1–155.
  21. ↑ Eugen Geinitz: "On the geology of the Lübenheener mountain range (I and II)", Schwerin State Library; In: Archives of the Association of Friends of Natural History in Mecklenburg, Vol. 65 (1911), pp. 65–70 and Vol. 66 (1912), pp. 49–55.
  22. ↑ State Main Archives Schwerin, inventory signature 5.12-3 / 18, Mecklenburg-Schwerinsches Bergamt, No. 17, "Statistics of Potash Mining (1911-1926)".
  23. ↑ a b c d e Schwerin State Main Archive, Mecklenburg-Schwerin Mining Authority , holdings signature Bergamt No. 52, "Files pertaining to the operation of the mine in Lübenheen" , Volume 3.
  24. ↑ State Main Archives Schwerin, holdings signature No. 10.21-13, No. 16, Union Conow zu Lübenheen , 1911–1927, diary 1.8.15 - 7.3.16 , pages unnumbered.
  25. ↑ a b State Main Archives Schwerin, holdings signature 5.12-3 / 18, Großherzogliches Mecklenburger Bergamt Hagenow, No. 37 , "Der Betrieb des Bergwerkes Conow 1917–1929", pages unnumbered.
  26. ^ R. Kühn: Chemical points of view on the question of the origin of the brines in the Ruhr area. Journal of the German Geological Society Volume 116 (1964), pp. 254–256, January 1, 1964, accessed on February 10, 2013 .
  27. ↑ State Main Archives Schwerin, inventory signature 10.21-13, Conow union in Lübenheen, No. 23, diary about the work of the company officials , pages unnumbered.
  28. ↑ a b State Main Archives Schwerin , holdings signature 5.12-3 / 18, Großherzogliches Mecklenburger Bergamt Hagenow, No. 37 , "Der Betrieb des Bergwerkes Conow 1917–1929", pages unnumbered.
  29. ↑ a b State Main Archive Schwerin , inventory signature 6.11-14, No. 3587, No. 3587, Ministry of Economics, HA Industry, Dept. Coal and Energy, Salt Deposits, Conow-Sülze potash works, Ludwigslust district , pages unnumbered.
  30. ↑ http://www.guenter.pinzke.de/bergbau/galerie.html . Adobe PDF document (2.1 MB)
  31. ↑ http://www.guenter.pinzke.de/bergbau/galerie.html . Adobe PDF document (1.5 MB)
  32. ↑ a b 'Bruno Baumert: "About liquor and water inflows in German potash mining". Dissertation from Aachen University of Technology, Gerstenberg Brothers, Hildesheim 1928, page 41
  33. ↑ Martin Heinz Wolf, dissertation, University of Leipzig: Visualization and quantification of the fluid dynamics in drill cores from the saline and overburden of the Staßfurt area using positron emission tomography. (PDF; 47.9 MB) September 19, 2011, accessed on February 14, 2013 .

Web links

Commons : Potash and Rock Salt Mine Conow  - Collection of images, videos and audio files

glossary

  1. ↑ Lauge: mining term . Term used in salt mining for salt solutions from the surrounding saline that enter mine workings, regardless of their genesis , chemical composition (saturated or unsaturated alkaline solutions) and the amount of material added ( "bulk material" ).
  2. ↑ Drowning: The mining term for the partial or complete filling of a mine through the ingress of water or salt solutions.