The casting industry uses large quantities of quartz sand, which is a cheap and accessible raw material that must be prepared for use in foundries. After the casting process, foundries generate huge amounts of waste foundry sand (WFS) as industrial waste. The regeneration and reuse of waste foundry sand is a practice and a necessity in many foundries for technological, environmental, and economic reasons. In this review paper, in addition to the characteristics of quartz sand for the casting industry and the characteristics of WFS, typical processes of regeneration in industrial practice, as well as the possibilities of using such recycled WFS in other industries, are presented.