This disclosure relates generally to the field of sand cast molding and to improvements in the founding of metals. This disclosure also relates to improvements in sand molding media employed in forming molds into which molten metal is poured in the production of castings through recovering the molding waste for recycling into sand molding additives and molding compositions. A method of forming a dry molding sand additive may include recovering a non-sand fraction from a foundry waste material and adding the non-sand fraction to a dry molding sand additive formulation to form a dry molding sand additive. Adding the non-sand fraction to the dry molding sand additive formulation may reduce the amount of fresh clay and carbon to produce the dry molding sand additive. A method of forming a molding sand additive may include recovering a waste molding sand additive composition having a clay or carbon content differing from a desired clay and carbon content, recycling the waste molding sand additive as a raw material in production of a fresh molding sand additive, and adjusting the amount of fresh clay or carbon added during production of the fresh molding sand additive to achieve the desired clay and carbon content. The non-sand fraction may include a recovered clay component and a recovered carbon component. The foundry waste material may include bag house dust, overflow green sand, or a mixture of bag house dust and overflow green sand. The foundry waste material may also include molding waste. The moisture content of the dry molding sand additive is in a range from about 0% to about 15% by weight. The method of forming a dry molding sand additive further comprises adjusting the composition of the dry molding sand additive such that the methylene blue adsorption value of the dry molding sand additive is in a range from about 70% to about 95%, the clay content of the dry molding sand additive is in a range of from about 60wt.% to about 90wt.%, and the carbon content of the dry molding sand additive is in a range of from about 10wt.% to about 25wt.%. The method of forming a dry molding sand additive further comprises at least partially dewatering the non-sand fraction by spray drying. Said spray drying reduces the moisture content of the non-sand fraction to less than about 30% by weight. The green sand prepared using the dry molding sand additive has a compactability greater than about 45%, a green compression strength greater than about 15.5 N·cm-2, a green shear strength greater than about 3.5 N·cm-2, a permeability greater than about 65, and a dry compression strength greater than about 36 N·cm-2.