Backfilling sands
Backfilling sands are used in making hydraulically placed fill – a mixture of sand and water to fill voids created by underground mining. Over the last few decades this has been the most popular form of underground mining backfilling. Documented backfilling sands deposits are situated mainly in the areas of intense underground mining, especially those of hard coal and copper mining in the Upper Silesian Coal Basin and the Lubin vicinities. One of the major requirements which sand deposits should meet to be classified as backfilling sand deposits is location in distance less than 50 km from the place where the raw material is to be used.
The majority of backfilling sand deposits are situated around the Upper Silesian Coal Basin. Three main deposits areas are differentiated: eastern, western and northern. The eastern area which is the center of production of that raw material extends from Kuźnica Warężyńska through the Pustynia Błędowska Desert as far as the vicinities of Jaworzno. It is characterized by occurrence of sands of fluvioglacial and locally eolian origin attaining up to 70 m in maximum thickness in the Pustynia Błędowska Desert. The second area with the largest resources comprises the Pleistocene valley of the Odra River in a part of the Racibórz Basin and a western part of the Silesian Upland and its sand deposits are from 15 m to 20 m thick at the average. The northern area comprises the Mała Panew River valley with its sand deposits up to 40 m in thickness. The deposits are well explored but still undeveloped. Sandy-gravel deposits up to 30 m in thickness also occur in copper mining areas in the vicinities of Lubin.
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 2016, anticipated economic resources of backfilling sands amounted to 2,641.51 million m3 (or about 4,490.57 million tonnes as recalculated using weight-to-volume ratio 1.7 t/m3). Resources increased by 74.43 million m3 mainly due to the correction of Strzybnica deposit resources (the growth by 33 million m3) which was the result of collecting by the National Geological Archive a missing new documentation with recalculated resources. Moreover, the resources grew by reclassification of resources within protective pillars to the resources beyond these pillars for Pustynia Błędowska – blok IV deposit. There was also a new documentation with recalculated resources approved for Marklowice deposit where a part of anticipated sub-economic resources was reclassified to anticipated economic resources (19.5 million m3). Anticipated economic resources decreased in Pole Brynica deposit (there was also a change of name – the former name was Brynica) due to the approval of a new documentation with recalculated resources. The other reasons for resources reduction were exploitation and losses in exploited deposits.
Economic resources decreased by 4.09 million m3 in comparison with 2015, due to the exploitation and losses. In 2016 no new deposit development plans for backfilling sands deposits have been elaborated.
Production of backfilling sands totaled 2,911 thousand m3 (4,949 thousand tonnes) being by 638 thousand m3 (18%) lower than in the previous year. The production dropped in all of seven deposits which have been under exploitation in the years 2015-2016. The most significant decline (more than 100 thousand m3) occurred in Bór (Zachód), Kotlarnia p.północne and Pustynia Błędowska – blok IV deposits. In 2016 the exploitation from Bór (Wschód) deposit was resumed whereas from Kuźnica Warężyńska was still on hold.
The figure given below shows changes in domestic resources and production of backfilling sands in Poland in the years 1989-2016.
Prepared by: Agnieszka Malon
Table 1. Backfilling sand - million m3