Foundry sands
Foundry sands are the basic raw material for making moulds and cores used in metal casting. The sands have to be characterized by high sintering temperatures as the temperature required for making cast steel is 1,400°C, for cast iron – 1,350°C, and for non-ferrous casting alloys - 1,200°C. Two types of foundry sands are differentiated on the basis of cement and carbonates content: pure quartz sands and natural foundry sands. The raw material coming from some of foundry sands deposits can also be used in other applications. Pure quartz sands are used as glass sands or sands for building and road industries.
Deposits of foundry sands are situated mainly in the central and southern parts of Poland and usually have the form of sand sheet deposits (map). The sand deposits range in age from the Quaternary and Miocene to Cretaceous and even Jurassic and Triassic. In the vicinities of Częstochowa, natural foundry sand deposits of varying thickness represent infills of karst forms developed in Upper Jurassic limestones. Foundry sand deposits from the area between Gorzów Śląski and Żarki are represented by fine- to medium-grained sands and sandstones of the Lower Jurassic age. In turn, weakly cemented sandstones or locally loose sands of the Middle Jurassic age form foundry sand deposits found in the vicinities of Szydłowiec, Wąchock, Skarżysko-Kamienna and Jagodna as well as Opoczno and Iłża. Cretaceous deposits of foundry sands are known mainly from the Tomaszów Basin (where they co-occur with those of glass sands) as well as from the Bolesławiec Basin and the vicinities of Krzeszówek in the Lower Silesian region. Foundry sand deposits formed of Tertiary sands deposited in land environments occur in the Konin area, at the margin of the Holy Cross Mts. and in Pomerania, and those formed of Tertiary sands of marine origin – in the Lublin Upland. Foundry sand deposits of the Quaternary age occur in the northern Poland and are formed of sands of dune fields or fluvioglacial terrace accumulations.
Anticipated economic resources of foundry sands increased by 15.33 million tonnes and amounted to 304.12 million tonnes in 2016. The resources growth was the result of approving a new documentation with recalculated resources for Szczakowa deposit (the extension of deposit boundaries - +15,679.71 thousand tonnes). The resources drop was caused by the exploitation (-1.08 million tonnes).
Anticipated economic resources of exploited deposits are covered by the detailed exploration (categories A, B and C1) and are equal 51.88 million tonnes accounting for 17.1 % of total anticipated economic resources.
Table 1 shows resources and the state of development and exploration of foundry sands in Poland.
Economic resources of foundry sands decreased by 1.53 million tonnes in comparison with 2015 due to the exploitation (-1.08 million tonnes) and losses. These drops were compensated mainly by the approval of a new deposit development plan with recalculated resources for Grudzeń-Las deposit where 0.56 million tonnes of sub-economic resources were reclassified to economic resources. The output of foundry sands in 2016 amounted to 1,081 thousand tonnes and slightly decreased (by 21 thousand tonnes – 2%) in comparison with the previous year. The output from Szczakowa deposit dropped by 76.24 thousand tonnes and from Ludwików – Pole B deposit by 8.69 thousand tonnes. The exploitation from Zawisna II deposit is still on hold. The exploitation from Grudzeń-Las deposit and Ludwików Pole B-1 deposit decreased by 57.91 thousand tonnes and by 6.16 thousand tonnes, respectively.
The figure given below shows changes in domestic resources and production of foundry sands in Poland in the years 1989-2016.
Prepared by: Agnieszka Malon
Table 1. Foundry sands - million tonnes