Phosphorites
Phosphorites are mainly used by an agriculture industry (the production of phosphate fertilizers). They are also used, but with a much less importance, in a chemical industry as a raw material for the production of various phosphorus compounds.
In Poland phosphorites occur mainly in the form of calcium phosphate-rich nodules in the various types of sediments in the belt of the Albian (the Lower Cretaceous) outcrops at the north-eastern margin of the Holy Cross Mts. (vicinities of Radom-Iłża-Annopol-Gościeradów-Modliborzyce). They are used for the production of the natural phosphate fertilizers. The exploitation of phosphorites started in Poland between the First and the Second World War. However, nowadays any of deposit is being under exploitation due to the economic reasons. The Chałupki mine was closed in 1961 and the Annopol mine in 1971.
The actual Polish limit values of the parameters that defines the phosphorites deposit establish that: the maximum depth of deposits documentation is 400 meters below the surface, 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.
The abundance parameter deviates significantly from the limiting parameters that define the phosphorites deposit. Deposits are flooded which results in their potential exploitation, moreover, their significant parts have been built-up or covered by roads, railways and high-voltage lines. In extreme cases, it may cause the resources available for exploitations reduction as much as 50-80%. For these reasons, all of the phosphorites deposits were crossed out from “The balance…” in 2006 and the domestic demand for the phosphorites raw materials is fully covered by import. In the latest edition of The balance of prospective mineral resources of Poland there was lack of economic conditions for qualifying the phosphorites occurrences in Poland as the prognostic resources stated. In light of the current balancing criteria, such occurrences are not economically significant*.
Phosphorites were documented – on the basis of the more detailed deposit exploration – as one of the accompanying raw materials in the new geological documentation (supplement No. 1) with recalculated resources of the glauconite-bearing sediments Niedźwiada II deposit approved in 2020. The deposit is located in Lubartów county in Lubelskie Voivodeship (Table 2). Phosphorites occur in the deposit in the form of hard phosphate concretions with irregular surface, of the grey-black color and with the granulation between 2 and 30 mm. The phosphate phase was defined as hydroxyapatite. These phosphorites are characterized by the high phosphorites content (the average content of P2O5 – 22.86%), with the limit values for phosphorites minimum 15% P2O5. In 2021, there was a concession for the exploitation of phosphorites from the Niedźwiada II deposit issued and the economic resources were assessed to be equal 7.33 thousand tonnes.
The state of the resources exploration and the state of the deposits development, together with the output amounts from particular deposits are presented in the Table 2.
Prepared by: Robert Bońda
* Gąsiewicz A., 2020 - "Fosforyty (phosphorites)". In: "Bilans perspektywicznych zasobów kopalin Polski wg stanu na 31.12.2018 r." (eds. Szamałek K., Szuflicki M., Mizerski W.): 233-236. PIG-PIB, Warszawa [in Polish].
Table 1. Qualitative parameters of the main phosphorites occurrences