NOVELTY - A cyclic method for production of crystalline silicon (Si), silane, silicon nitride or carbide and hydrogen (H2) is based on pyrolysis of oil-containing sand or shale (I) (as mixture of hydrocarbons and silicates), contaminated with potassium aluminum silicate and carbonate. Released H2 is heated with fluorine to give hydrogen fluoride, which is reacted with the Si of (I) to give silicon tetrafluoride for conversion into Si by thermite methods using aluminum.    USE - For cyclic, large-scale production of (i) crystalline silicon (specifically for conversion into photosilicon), the fuel silane or the ceramics silicon nitride or silicon carbide and (ii) very large amounts of gaseous hydrogen (specifically for use in current generation for the electrolysis stage, the excess being fed into a gas main) (all claimed). Monosilane obtained using the process is specifically converted into longer chain silanes, for use in fuel cells, ceramic-based motors without mechanical elements or scramjet drives (all claimed). More generally silanes are useful as fuels of non-petroleum origin for combustion engines in the automobile, air travel, warfare and space travel sectors.    ADVANTAGE - High purity crystalline Si is obtained (together with large amounts of H2 and pure carbon or graphite) using primary energy from tar oil (whereas the convention 3-stage method uses coke, electrical heating to more than 2000 degrees C and pyrolysis of chlorosilanes); in addition to utilizing this energy (normally not usable due to interference by sand, feldspar and shale), the present process converts all impurities in the sand (using hot HF) into gases removable for discharge using potassium hydroxide solution (all claimed). The oil-containing sand or shale materials (I) are readilly available in very large quantities. The process specifically allows the price of photosilicon to be reduced 100-fold compared with the conventional method. The pyrolysis vessel wall is permanently heated to a temperature of only ca. 400 degrees C.    DETAILED DESCRIPTION - Cyclic production of crystalline silicon (Si), silane, silicon nitride or carbide and hydrogen (H2) involves pyrolyzing oil-containing sand or shale (I) (as mixture of hydrocarbon energy source (tar) and silicates (SiO2)), contaminated with potassium aluminum silicate and carbonate, at more than 2000 degrees C. The released H2 is fed into a gas main or heated at ca. 4000 degrees C with a specific amount of fluorine (F2) to give hydrogen fluoride (HF). The hot HF is immediately reacted with the Si of (I) to give silicon tetrafluoride (SiF4) gas and water vapor; and the hot SiF4 (contaminated with HF) is fed directly into a combustion chamber supplied continuously with aluminum (Al) powder, in which SiF4 is converted into high purity crystalline Si by a thermite process. The obtained Al fluoride (AlF3) powder (stable towards aqueous base) is filtered off before electrolytic conversion (in hexafluorosilicate form) into more Al and F2. The necessary DC current is permanently obtained using process heat; the thermite process stoichiometrically releases 1172 KJ of energy per unit time and cooling with preheated water gives steam for AC generation. Heat from SiF4 production is also used for electricity generation. In the pyrolysis stage, the SiF4-H2O mixture is passed into the center of an Al powder-filled rotating drum with a welding flame in the cylinder center, and heat conduction causes exponential decrease of high temperatures in the cylinder wall direction (as in the subsequent thermite process). Cooling of the double-walled drum with water allows generation of a large amount of current, and Al and F2 are recycled to the cyclic process.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of a plant for producing crystalline silicon and hydrogen using oil sand. (Drawing includes non-English language text).    Oil sand pyrolysis (1)    Pure carbon (graphite) recovery (2)    Thermite process (3)    Vibrating sieve separation of mixture of silicon, aluminum fluoride and hydrogen (4)    Crystalline silicon recovery (5)    Recyclic of aluminum fluoride (6)    Excess hydrogen supply to gas main (7)    Recycling of stoichiometric amount of hydrogen (8)    Melt electrolysis (9)    Granular aluminum supply (10)    Recycling of fluorine (11)    Aluminum recovery (12)    Current generation using hydrogen (13)    AC generation (14)