Backfilling sands
Backfilling sands are used for making a hydraulically placed fill – a mixture of sand and water to fill depleted mining excavations. Documented backfilling sands deposits occur in the areas of an intensive underground mining, especially those of the hard coal and copper mining in the southern part of Poland, mainly in the Upper Silesian Coal Basin area and in Lubin vicinities. One of the major requirements which sand deposits should meet to be classified as backfilling sand deposits is the location at the distance less than 50 km from the place where the raw material is to be used.
The majority of backfilling sand deposits is located around the Upper Silesian Coal Basin. Three main deposit areas can be differentiated: eastern, western and northern. The eastern area (where the majority of the raw material volumes is exploited) extends from Kuźnica Warężyńska through the Pustynia Błędowska Desert as far as the vicinities of Jaworzno. It is characterized by the occurrence of sands of fluvioglacial and partially eolian origin, attaining up to 70 m in a thickness (Pustynia Błędowska Desert). The second area with the largest resources covers the proglacial stream valley of the Odra River in a part of the Racibórz Basin and a western part of the Silesian Upland. The average thicknesses of the deposits located within this area are within the range of 15 – 20 m. The northern area covers the Mała Panew River valley where fluvioglacial sand deposits occur, characterized by the significant thicknesses (up to 40 m). The deposits are explored well enough but have not been developed so far. Moreover, sandy-gravel deposits up to 30 m in thickness occur in the copper mining areas in the vicinities of Lubin.
The clastic rock raw materials occurrence in Poland (including backfilling sand) is presented on the map.
The table given below shows resources and the current state of exploration and development of backfilling sand deposits.
In 2018, anticipated economic resources of backfilling sands amounted to 2,515.08 million m3 (or about 4,275.64 million tonnes as recalculated using a weight-to-volume ratio 1.7 t/m3). The resources decreased by 2.53 million m3 due to the exploitation and losses. The anticipated economic resources slightly increased (by 315 thousand m3) only in Szczakowa-Bukowno deposit located in Małopolskie Voivodeship. It was the result of the approving of a new documentation with recalculated resources for this deposit as the entrepreneur will be applying for an exploitation concession. It was the only geological documentation of backfilling sands accepted in 2018. The number of backfilling sands deposits dropped by 2 due to the crossing out in 2017 from “The balance…”: Pustynia Błędowska – obszar pozostały and Szczakowa pole II deposits.
Economic resources decreased by 2.09 million m3 in comparison with 2017, due to the exploitation and losses. The drop was partially compensated by the economic resources growth in the following deposits: Obora in Dolnośląskie Voivodeship and Bór (Zachód) in Śląskie Voivodeship. The growth was the result of supplements to the deposit development plans elaboration. The resources in Obora deposit was slightly adjusted – by 3 thousand m3 (0.02%), whereas in Bór (Zachód) deposit the resources classified up to now as losses (the part of the deposit located below the abandoned mine railway siding) were reclassified to the economic resources.
The output of backfilling sands from seven exploited deposits increased by 324 thousand m3 in comparison with the previous year and totaled 3,021 thousand m3 (5,136 thousand tonnes) in 2018. The production grew by about 200 thousand m3 from three deposits apiece, with the biggest increase for Pustynia Błędowska – blok IV deposit (+239 thousand m3), whereas the output drop was recorded in four deposits. There was not the exploitation carried out from Szczakowa pole I deposit in spite of the valid concession. The exploitation from Kuźnica Warężyńska deposit is still on hold.
The figure given below shows changes in domestic resources and production of backfilling sands in Poland in the years 1989-2018.
Prepared by: Agnieszka Malon
Table 1. Backfilling sand - million m3