In Poland, brown coal deposits occur in younger geological formations, mainly of the Tertiary age. Older brown coal deposits are known to occur also in the Jurassic, Carboniferous and rarely - Cretaceous and Triassic. The brown coals are intermediate in the qualification between hard coal and peat. Their characteristics and properties were markedly influenced by the type of the 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 the extensive seams from a few meters to several dozen meters in thickness. It also occur in the form of lenses. The thickness of overburden is usually quite small which makes the opencast mining of the deposits possible. Seams of older brown coals are often situated too deep below the surface level for the opencast mining and require the underground mining. This is also the case of coal seams occurring in glacitectonic folds. The methods of the underground mining were lately used in Poland to mine coals in Babina and Sieniawa deposits.
There is brown coal deposits occurrying in Poland presented on the map.
Brown coal resources are documented with taking into account the following limit values of the parameters that define the deposit for the opencast mining: the maximum depth of deposit base of 350 m, the minimum brown coal layer thickness in bed of 3 m and the maximum ratio of overburden and intercalation sum/deposit thickness of 12:1. The minimum weighted-average calorific value in a bed (with intercalations) should equal 6.5 MJ/kg (at the brown coal humidity of 50%). These are the basic criteria of geological-mining parameters and qualitative parameters for energy coals which are common in Polish deposits – typical ortholignites.
Poland’s anticipated economic resources of brown coal amounted to 23,315.52 million tonnes as of the end of 2018. The majority of resources – that is 23,314.88 million tonnes – constitute energy coals, remaining 0.64 million tonnes are bituminous coals. There were also coals usable for the production of briquettes and coals suitable for the production of coal tar and liquid through a distillation documented in the past. Currently, all these coals are used and treated as energy coals only.
Table 1 shows resources and the current state of the exploration and development of brown coal deposits in Poland.
Anticipated economic resources within exploited deposits amount to 1,224.50 million tonnes and account for 5.25% of total anticipated economic resources. Brown coal is being exploited by five mines: Bełchatów, Turów, Adamów, Konin and Sieniawa.
About 16.5% (3,690 million tonnes) of anticipated economic resources constitute the resources of the deposits within the Poznań through. These are Czempin, Gostyń, Krzywin and Mosina deposits where potentially strip mining is nowadays precluded on the environmental grounds and in connection with large scale of production farms. These are the main issues to be solved by the local societies, the ecological organizations and the supporters of the deposits development, before the exploitation starts. It might seriously complicate the deposit development in the future.
Table 2 shows basic parameters of non-exploited deposits with anticipated economic resources exceeding 75 million tonnes.
Anticipated economic resources of brown coal amounted to 23,315.06 million tonnes in 2018 and decreased by 69.54 million tonnes in comparison with the previous year. The resources drop is mainly the result of the exploitation but also of: - the exploitation losses; - the declines/growths coming from the better deposit exploration which are showed by concession holders in their reports (and in their inventories of mineral deposit resources).
Economic resources of brown coal as of 31.12.2018 amount to 1,047.60 million tonnes and increased by 55.02 million tonnes in comparison with 2017. The economic resources changes are connected with: - the elaboration of supplements to deposit development plans, prepared mainly due to exploitation boundaries changes or the better deposit exploration; - the exploitation, the declines resulted from losses and the deposit exploration during the exploitation. There were supplements to deposit development plans established for Bełchatów-pole Bełchatów and Bełchatów-pole Szczerców deposits which resulted in economic resources growth in spite of proceeding exploitation – by 75.58 million tonnes.
The brown coal output, according to the data provided by the concession holders, decreased in 2018 by 1,916 thousand tonnes (3.04%) in comparison with the previous year and amounted to 61,144 thousand tonnes. The exploitation from Sieniawa 2 deposit started in 2018. The majority of the output came from Bełchatów-pole Szczerców deposit (34,644 thousand tonnes which accounted for 56.66% of the domestic production), whereas the exploitation from Bełchatów-pole Bełchatów deposit amounted to 12,180 thousand tonnes (19.92% of the domestic production). The gradually increasing of the output from the Szczerców field compensates the decreases within the Bełchatów field allowing to maintain the stable level of the output for the Bełchatów power station. The production from other deposits accounts for: Turów – 10.78% of domestic production (6,593 thousand tonnes); whereas in the deposits located in the Konin area: Pątnów IV – 5.19% (3,171 thousand tonnes); Tomisławice – 2.78% (1,702 thousand tonnes), Drzewce – 3.18% (1,946 thousand tonnes) and Adamów – 1.30% (796 thousand tonnes). The remaining output came from Sieniawa 1 and Sieniawa 2 deposits and amounted to 111 thousand tonnes (0.18% of the domestic production). In comparison with 2017 the output increased only from Bełchatów-pole Szczerców deposit: - by 6,839 thousand tonnes (24.60%), moreover, the exploitation from Sieniawa 2 deposit started in 2018 (60 thousand tonnes). In other deposits, there were the output drops recorded: - by 4,544 thousand tonnes (27.21%) from Bełchatów-pole Bełchatów deposit; - by 2,143 thousand tonnes (72.92%) from Adamów deposit (due to the shutting down of the Adamów power plant at the end of 2017 and heading up the exploitation form the deposit for the Pątnów I and II power plants which allows to the better utilization of the resources remaining in the deposit); - by 1,257 thousand tonnes (28.39%) from Pątnów IV deposit; - by 438 thousand tonnes (20.47%) from Tomisławice deposit; - by 276 thousand tonnes (4.02%) from Turów deposit; - by 116 thousand tonnes (5.63%) from Drzewce deposit; - and by 33 thousand tonnes (39.29%) from Sieniawa 1 deposit.
The figure shows changes in the resources and production of brown coal in Poland in the years 1989-2018.
In the Table 3 given below there is the state of resources exploration, the state of deposits development along with the output volumes presented for the whole country.
Prepared by: Sławomir Mazurek, Marcin Tymiński