TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The composition comprises 35-80 wt.% silicon dioxide, 40-60 (preferably 40-55) wt.% sodium carbonate, 0.50-6 wt.% calcium fluoride, and 4-6 wt.% calcium chloride. The calcium oxide is absent. Preferred Method: The silicon that forms molten liquid comprises metallurgical grade (MG), solar grade (SOG) silicon and silicon recycled from silicon purification process. The step (i) is carried out, such that molten liquid of silicon is initially formed and flux is subsequently added to molten silicon or solid silicon is initially contacted with flux and together heated to form molten liquid. The molten liquid is formed at, at least 1450 degrees C or above solidus temperature. The method additionally involves directionally solidifying the purified molten liquid, to form solid silicon; and removing portion of solid silicon to provide purified solid silicon. The flux is present on an internal surface of furnace refractory, which is configured to protect molten silicon from contamination by impurities from the furnace refractory. The directional solidification is carried out by cooling purified molten liquid, to temperature of less than the liquidus temperature of purified molten liquid. The purified molten liquid is cooled to above the solidus temperature of purified molten liquid and below liquidus temperature of purified molten liquid. A top portion of the purified molten liquid is maintained above the melting point, while bottom portion of the purified molten liquid is cooled below the freezing point. The directional solidification is carried out by cooling the purified molten liquid to within about 125 degrees C above the solidus temperature or above the melting point of purified molten liquid. The directional solidification is carried out by cooling the purified molten liquid at bottom portion of directional solidification mold, at rate of less than about 75 degrees C/hour; or cooling the purified molten liquid over a period of time of at least 18 hours. The portion of the solid silicon is removed by cutting solid silicon. At least one step is independently carried out multiple times. Preferred Components: The slag comprises reaction product of flux and impurities from the silicon. The slag forms on surface of molten liquid, and is subsequently removed from the molten liquid. EXAMPLE - No suitable example is given.