A highly efficient process is disclosed for making proppants from generally non-spherical or discretized raw material, such as naturally occurring sand or pelletized refractory material. In one embodiment of the process, the discretized material is heated by a counter-current flow of hot gas in a first Moving Bed Gas-Solids Direct Contact Heat Exchanger (MBGSDCHX). The heated discretized material is then further heated to a transformative temperature by a raw material transformation means to a partially or fully melted state in which the discretized raw material assumes generally spherical shapes. The spheres are then cooled by a counter-current flow of cold gas in a second MBGSDCHX. The cooled spheres are then size-classified for use as proppants. In an alternate embodiment, refractory raw material is melted and then discretized into molten drops. The molten drops are cooled and frozen into generally spherical shapes. The cooled spheres are used as proppants.