Memorial site marking the XIV. Szent István Lejtősakna of the short-lived Nagyegyházi Bányaüzem, a brown coal inclined shaft opened under Hungary's Eocén program and closed in 1989.
The XIV. Szent István Lejtősakna was an inclined haulage shaft of the Nagyegyházi Bányaüzem, opened as part of Hungary's state-directed Eocén program of the 1970s and 1980s. The Nagyegyháza mine was constructed by the Tatabányai Szénbányák Vállalat from 1976, with inclined shaft development beginning in early 1977.
Coal production commenced in 1981, with full operation under way by 1985. The mine was conceived as a three-commodity operation extracting coal, bauxite, and karst water, but persistent and costly karst water inflows rendered the operation uneconomic. A statutory limit on the volume of karst water that could be pumped — imposed to protect thermal springs in the Budapest area — made continued operation impossible, and the mine was shut down at the end of 1989.
A miners' memorial incorporating an overturned coal skip was erected in the village of Nagyegyháza in 2019 at the initiative of the widow of a local miner, on or near the site of the former shaft. The current entry records the emlékmű (memorial) at the site of the XIV. Szent István Lejtősakna.
The Nagyegyháza brown coal deposit lies in the Tatabánya coalfield's eocén-age extension south of the main Tatabánya medence, beneath the Gerecse foothills in Fejér County. Coal-bearing strata at depths inaccessible to earlier workings were identified during geological surveys in 1924, and further confirmed by later exploration, but development was not initiated until the energy crisis context of the mid-1970s. Hungary's Eocén program — approved by the Állami Tervbizottság in decision 5071/76 in 1976 — planned the opening of four new deep brown coal mines: at Márkushegy, Nagyegyháza, Mány, and Lencsehegy, together with reconstruction at Dudar and Balinka. The combined output was intended to supply a projected 1,930 megawatt power station at Bicske. The Nagyegyházi Bányaüzem was allocated to the Tatabányai Szénbányák Vállalat and placed under the Ipari Minisztérium.
Sinking of the F-1 and V-1 vertical shafts of the Nagyegyházi Bányaüzem began in autumn 1976. The inclined eastern (K-i) and western (Ny-i) lejtősaknák were begun in early 1977. The western inclined shaft reached a length of 212 metres by November 1977, when a DOSCO MK-2A tunnelling machine was commissioned underground. Underground connection between the F-1 vertical shaft and the Ny-i lejtősakna was achieved in 1978, and construction of the central pithead bath and office building also began in that year. A heavy-medium separation plant was under development by 1978. The mine was conceived from the outset as a three-commodity operation: the coal seams overlay significant high-quality bauxite reserves, and the karst water encountered during extraction was of mineral water quality intended for supply to Budapest.
Coal production commenced in 1981. The mine was equipped with the most modern longwall face-support shields and radio-remote-controlled shearing machines available. Special gas-damping safety valves were incorporated into the hydraulic systems of the shields to mitigate the risk of dynamic loading from rock bursts. Full operation was under way by 1985. However, the anticipated bicskei power station was cancelled following the change in national energy strategy, and the mine's production plans were revised downward in 1981. Karst water inflows proved a persistent and ruinous problem: in 1987 approximately 130 cubic metres per minute of karst water had to be pumped continuously to maintain safe working conditions, and a single inflow into a main roadway required the injection of some 630 tonnes of cement to seal. The cost of water management alone made profitable operation impossible at the state-controlled coal price.
When regulators imposed a drastic reduction in the permitted volume of karst water that could be pumped — on the grounds that the Budapest thermal springs were being depleted — viable operation became impossible. A decision to suspend the mine was taken, and the Nagyegyházi Bányaüzem was definitively closed at the end of 1989. The mine is widely cited as one of the most costly failures of Hungary's socialist planned economy, with its capital costs written off entirely as a state loss.
The mine site at Nagyegyháza was subsequently reclaimed. The village of Nagyegyháza and the neighbouring settlement of Óbarok had many residents who had worked either in the main Tatabánya medence mines or in the Nagyegyházi Bányaüzem itself. In August 2019, on the occasion of the 20 August national holiday, a miner's memorial was unveiled in the village centre of Nagyegyháza at the initiative of the widow of a local miner named Nagy Zoltán, supported by the Óbarok–Nagyegyháza joint municipality. The memorial takes the form of an overturned coal skip from which stones, rather than coal, spill out. The former chief engineer of the mine and the former chief executive of the Tatabányai Bányák both spoke at the unveiling ceremony. The canonical name XIV. Szent István Lejtősakna refers to one of the inclined shafts of the Nagyegyházi Bányaüzem, named after Hungary's first king, Stephen I (Szent István), whose feast day falls on 20 August.