what type of sand is used for molding blocks in nigeria

Sep 11, 2019 Backing sand is sometimes called black sand because of old, repeatedly used molding sand is black in color due to addition of coal dust and burning on coming in contact with the molten metal. 2.2 Core sand. Core sand is used for making cores and it is sometimes also known as oil sand. Core sand is highly rich silica sand mixed with oil binders ...