In Poland, brown coal deposits occur in young geological formations, mainly the Tertiary. Older brown coal deposits are known to occur also in the Jurassic, Carboniferous and locally even Cretaceous and Triassic in several places in the world. The brown coals are intermediate in coalification between hard coal and peat. Their characteristics and properties were markedly influenced by the type of parent plant material and environment in which they originated.
Brown coal deposits originated both in platform areas and sedimentary basins in orogenic belts. The coals form extensive seams or lenses a few meters to several dozen meters in thickness. Thickness of overburden is usually quite small which makes possible opencast mining of the deposits.
There are brown coal deposits occurying in Poland presented on the map.
Seams of older brown coals are often situated too deep underground for opencast mining and require underground mining. This is also the case of coal seams occurring in glacitectonic folds. The methods of underground mining were lately used in Poland to mine coals in the Babina and Sieniawa deposits.
Brown coal resources are calculated to the maximum depth of deposit base of 350 m, the minimum brown coal layer thickness in bed of 3 m and maximum overburden/deposit thickness ratio of 12 : 1. The minimum weighted-average calorific value in bed (with intercalations) should equal 6.5 MJ/kg (at brown coal humidity of 50 %) and maximum medium sulphur content equal 2 % (for brown coal bed with intercalations and at humidity of 50 %). These are the basic balance criterias for energy coals which are common in Polish deposits.
Criterias mentioned above were the basis while assessing prognostic brown coal resources which were calculated to be equal 27,540.71 million tonnes as of 31.12.2009(1). This figure is more than 40 % higher than anticipated economic resources calculated as of 31.12.2010. Prognostic resources occur in 90 prognostic deposits or prognostic areas near documented deposits within 7 coal-bearing regions: bełchatowski, koniński, legnicki, łódzki, północno-zachodni, wielkopolski i zachodni. The most important are prognostic resources in satellite deposits for mine-power boards.
At the end of 2010 Poland’s anticipated economic resources of brown coals amounted to 19,819 million tonnes. The resources comprise 0,8 million tonnes of bituminous coal, about 2,513 million tonnes of coals usable for production of briquettes and about 1,496 million tonnes of coals suitable for production of coal tar and liquid through distillation. Nevertheless, all these coals are used and treated as energy coals only. The Bełchatów brown coal deposit from the Piotrków Trybunalski area is the largest and most important and accounts for more than 58 % of domestic production of this raw material. The remaining demand for brown coal is covered by production from the Turów open cast mine in vicinities of Bogatynia and the Pątnów and Adamów mines in the Konin area. Works preceding start of exploitation are being continued at the Szczerców brown coal field of the Bełchatów deposit.
Production amounted to 56,516 thousand tonnes in 2010, being 545 thousand tonnes lower than in the previous year. Almost the whole production of the largest brown coal strip mines (Bełchatów, Turów, Adamów and Konin) was used as energy coal in power plants.
Table 1 shows resources and the current state of exploration and development of brown coal deposits in Poland.
Strip mining of brown coal of the Czempin, Krzywin and Gostyń deposits with total reserves of 3,690 million tonnes is nowadays precluded on environmental grounds and in connection with high class and value of agricultural lands in area of the planned open strip mine. Table 2 shows basic parameters of major non-exploited deposits with anticipated economic resources over 75 million tonnes.
The figure given below shows changes in resources and production of brown coal in Poland in the years 1989-2010.
In 2010 brown coal export amounted to 116.37 thousand tonnes (with the value of PLN 12.82 million), mainly to Czech Rep. (95 % - with the value of PLN 11.90 million) and Germany. Brown coal import amounted to 50.10 thousand tonnes (PLN 20.57 million) with Germany as main direction (30.75 thousand tonnes - PLN 15.63 million).
- B - for solid minerals - mine in building process, for fuels - prepared for exploitation or trial period of the exploitation
- E - exploited
- G - underground natural gas storage facilities
- M - deposit crossed out of the annual report of mineral resources during analized period
- P - deposit covered by preliminary exploration (in C2+D category, for fuels – in C category)
- R - deposit covered by detailed exploration (in A+B+C1 category, for fuels – in A+B category)
- Z - abandoned deposit
- T - deposit exploited temporarily
- K - change of the raw material in deposit
Prepared by: Janina Dyląg
(1)J. R. Kasiński, 2011 - "Węgiel brunatny" w "Bilans perspektywicznych zasobów kopalin Polski wg stanu na 31 XII 2009 r." pod red. S. Wołkowicza, T. Smakowskiego, S. Speczika. PIG-PIB Warszawa.