In diploma thesis I focused on the behavior of basic refractory material – silica sand in the foundry sand mixture. The main test encompassed comparing the resistance to mechanical loads of two silica sands from different producers. Samples were collected from two sieves from the sieve analysis of silica sand, ground in a lab mixer. The samples were compressed with a constant speed up to 40 kN of force on the Gleeble 1500 machine. From the measured data I obtained the force values at the individual local grain cracks for each sample. Using these values, the strength difference between the fractions and producers of silica sand was determined. After the sand had been compressed, I made a sieve analysis to estimate how many fine fractions were formed during the compressing process. With the test I wanted to assess the influence of silica sand origin on the durability of the basic refractory material in the foundry sand mixture. In the second part, I used the AFS clay content determination, sieve analysis and optical and electron microscopy to check, by using mechanical sand regeneration machine, enough impurities and fine fractions can be removed from the waste sand that the reclaimed sand could be reused in the preparation of foundry sand mixture with no negative effects on the molding sand quality.
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