Phosphorites
Phosphorites are mainly used by an agriculture industry for the production of phosphate fertilizers. They are also used in a chemical industry as a raw material for the 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 the Albian (Lower Cretaceous) outcrops at the north-eastern margin of the Holy Cross Mts. (vicinities of Radom-Iłża-Annopol-Gościeradów-Modliborzyce). The thickness of this phosphate-bearing series is varying from 0.2 m to 4 m. The content of P2O5 in the nodules is generally low, ranging from 13% to 22%. The 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 the economical reasons. The Chałupki mine was closed in 1961 and the Annopol mine in 1971.
Actual Polish limiting parameters 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 Polish phosphorites deposits are abandoned as their limiting parameters are markedly below cut-off grade for the economic exploitation. Deposits are flooded and their significant parts were built-up or covered by roads, railways and high-voltage lines. It may sometimes cause the resources reduction by 50-80%. These were the reasons why in 2006 the deposits have been crossed out from "The balance..." and a demand is fully covered by import.
Prepared by: Robert Bońda
Table 1. Qualitative parameters of the main phosphorites occurrences.