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 content of cement and carbonates: 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 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. The sand deposits range in age from the Quaternary and Miocene to Cretaceous and even Jurassic and Triassic.
In the vicinities of Częstochowa (map), small 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 (central Poland) where they co-occur with those of glass sands as well as from the Bolesławiec Basin and vicinities of Krzeszówek in the Lower Silesian region. Foundry sand deposits formed of Miocene 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 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.
Raw material from some deposits of foundry sands may also find other uses. Pure quartz sands are used also in glass industry and sometimes in construction and road building.
Anticipated economic resources decreased by 4.06 million tonnes in comparison with the previous year and amounted to 288.79 million tonnes in 2015. The resources drop was due to the resources correction by crossing Zaborze deposit out from “The balance…” (-2.92 million tonnes), the exploitation (-1.10 million tonnes) and losses.
Anticipated economic resources of exploited deposits (A, B, C1 categories) are equal 36.55 million tonnes accounting for 12.7% of total anticipated economic resources.
Table 1 shows resources and the state of development and exploration of foundry sands in Poland.
Economic resources decreased by 0.15 million tonnes in comparison with 2014 mainly due to the output (-1.10 million tonnes) and expiring of the exploitation concession for Unewel-wschód deposit (-0.97 million tonnes). On the other hand, there was a new calculation of resources within deposit development plan accepted for Grudzeń-Las deposit (the resources increased by 1.97 million tonnes).
In 2015 production of foundry sands was equal 1.103 million tonnes, decreasing by 250 thousand tonnes (18%). The exploitation dropped from Grudzeń-Las (by 254 thousand tonnes) and Ludwików – Pole B (by 38 thousand tonnes) deposits (Table 2). The output from Zawisna II deposit was stopped during the year and only 40 tonnes of raw material have been extracted.
The figure given below shows changes in domestic resources and production of foundry sands in Poland in the years 1989-2015.
Prepared by: Agnieszka Malon
Table 1. Foundry sands - million tonnes