Phosphorites are mainly used by agriculture industry for production of phosphate fertilizers. They are also used in chemical industry as raw material for production of various phosphorus compounds.
In Poland phosphorites occur in the form of calcium phosphate-rich nodules in sandy marls and glauconitic sands in the belt of outcrops of the Albian (Lower Cretaceous) at the north-eastern margin of the Holy Cross Mts. Thickness of this phosphate-bearing series is varying from 0.2 to 4 m. The content of P2O5 in the nodules is generally low, ranging from 13 % to 22 %. Concentration of the nodules in sediments of the phosphate-bearing series is also low, ranging from 280 kg/m2 to 900 kg/m2. It should be also added that the deposits are strongly saturated with water.
Phosphorites exploitation started in Poland between the First and the Second World War. Nowadays, any of deposit is being under exploitation due to economical reasons. The Chałupki mine was closed in 1961 and the Annopol mine in 1971.
Actual Polish deposit criteria for phosphorites deposits established that: the maximum depth of resources documentation is 400 metres below the surfaces, the minimum P2O5 content in calcium phosphate-rich nodules is 15 % and the minimum affluence of calcium phosphate-rich nodules is 1,800 kg/m2. Qualitative parameters of the main phosphorites occurrences are presented in table 1.
At present, all the Polish phosphorite deposits are abandoned as their reserve parameters are markedly below cut-off grade for economic exploitation. This was the reason why the deposits have been crossed out from Annual Report of Mineral Reserves-Resources and Groundwater Resources in Poland.
Prepared by: Robert Bońda