Some methods for making a granular material comprise crushing demetallized slag particles with one or more crushers and screening the crushed demetallized slag particles with one or more screens to separate the demetallized slag particles into two or more fractions, the granular material comprising at least one of the fractions of the demetallized slag particles. Prior to the crushing, ones of the demetallized slag particles having a size that is less than or equal to 2 inches can account for at least 90% of the demetallized slag particles. An iron-compound content of the demetallized slag particles, by weight, can be less than or equal to 10%. Crushing and screening can be performed such that ones of the demetallized slag particles of the granular material having a size that is less than or equal to 1.25 mm account for at least 90% of the demetallized slag particles of the granular material.

Pig iron and spherical silica-based proppant are extracted and produced through the use of formers, fluxes, reductants, and stabilizers, at predetermined specified weight ratios. The base material utilized in this process is slag, typically derived from the mining industry. The slag is delivered and utilized in a manner that allows the adding and mixing of the various materials such as, but not limited to, carbon, calcium oxide, sodium oxide, aluminum oxide, magnesium oxide, and potassium oxide. The formulated mixture is then heated for a predetermined period of time, based upon weight to a liquid state, wherein the molten pig iron is separated from the molten silica glass. The molten pig iron is then poured into molds, and the molten silica glass is atomized into spherical proppant. The process is particularly well suited to slags produced from copper smelting, but can be extended to slags from other commodities and industries.

A method of recovering Fe from steel-making slag is disclosed. The method includes the steps of melting steel-making slag having a higher Fe content than iron-making slag by heating the steel-making slag to a first temperature; cooling the molten slag to a second temperature that is lower than the first temperature and then maintaining the same at the second temperature for a predetermined time to thus precipitate Fe in the molten slag, thereby forming and growing an Fe-rich phase; rapidly cooling the slag to room temperature; and crushing the solidified slag and magnetically separating a magnetically-susceptible portion from a magnetically-unsusceptible portion.