Patent ES-8602534-A1 (ES)
Title: Process and apparatus for obtaining silicon from fluosilicic acid.
IPC: B01J19/26
Filed: 1983-12-26
Abstract: Process for producing low cost, high purity, solar grade silicon by reacting, in substantially stoichiometric quantities, liquid sodium introduced through a first inlet means at the top of a reaction chamber with gaseous silicon tetrafluoride introduced through a second inlet means surrounding the first inlet means, the reaction chamber being formed of graphite, and recovering the silicon reaction product by a melt sepn. technique, characterised in that the bottom portion of the reaction chamber has one more drainage ports therethrough of a size between 2 and 3.5 millimeters in dia. and the reaction is carried out so that sodium fluoride is continuously removed as a molten liquid by passing through the drainage ports due to the low surface tension thereof as compared to that of silicon and the silicon, which may be under liquid or solid form, is retained in the reaction chamber substantially free of sodium fluoride. - (16pp) EPAB- EP-151569 B Process for producing low cost, high purity, solar grade silicon by reacting, in substantially stoichiometric quantities, liquid sodium introduced through a first inlet means at the top of a reaction chamber with gaseous silicon tetrafluoride introduced through a second inlet means surrounding the first inlet means, the reaction chamber being formed of graphite, and recovering the silicon reaction product by a melt sepn. technique, characterised in that the bottom portion of the reaction chamber has one more drainage ports therethrough of a size between 2 and 3.5 millimeters in dia. and the reaction is carried out so that sodium fluoride is continuously removed as a molten liquid by passing through the drainage ports due to the low surface tension thereof as compared to that of silicon and the silicon, which may be under liquid or solid form, is retained in the reaction chamber substantially free of sodium fluoride. GBAB- GB2142918 B A process for the production of low cost, high purity, solar grade silicon by the reaction of molten sodium and gaseous silicon tetrafluoride, which comprises introducing the molten sodium and gaseous silicon tetrafluoride reactants into the upper region of a vertically orientated reaction chamber above a reaction mass contained therein and comprising molten product sodium fluoride and silicon, allowing the molten sodium and gaseous silicon tetrafluoride to react in said chamber to form said reaction mass, said chamber being constructed of a material which is preferentially wetted by said molten sodium fluoride and having a generally cylindrical wall portion and a bottom portion, allowing the molten sodium fluoride preferentially and selectively to flow through one or more drainage channels formed in the bottom of said reaction chamber and communicating with one or more drainage ports passing therethrough, and periodically or continuously withdrawing said molten sodium fluoride from the bottom of said reactor, thereby allowing product silicon to collect in the reaction chamber, and subsequently discharging the accumulated silicon product from the reaction chamber. USAB- US4584181 A A reaction chamber to produce solar grade Si by reacting gaseous SiF4 with Na to give a prod from which Si is obtd. by melt sepn includes a top inlet for liq. Na and a second inlet around the first for gaseous SiF4. - The chamber has a cylindrical wall and a bottom of graphite, the bottom having one or more drain ports preventing passage of molten Si but allowing passage of other reaction prods. - Drain channels in the bottom facilitate free flow of the other prods to the ports, and these pass through due to their low surface tension compared with Si. - The SiF4 gas is obtd. by thermal decomposition of Na fluorosilcate pptd. from aq. fluosilicic acid obtd from phosphate rock conversion to phosphate. The chamber sidewall may have vertical channels leading to the bottom channels.