Silicon Reduction of Iron Oxide

Abstract

Systems and methods for producing iron from iron oxide using silicon are disclosed. Slag is mixed with a first ore. The slag includes metallic silicon. The first ore includes iron oxide. The mixture is heated sufficient to initiate reduction of the iron oxide by the metallic silicon, producing metallic iron and silicon oxides.

What is claimed is: 
     
         1 . A method for producing metallic iron, comprising:
 mixing a slag, the slag comprising metallic silicon, with a first ore, the first ore comprising iron oxide, to produce a first mixture; and   reducing the iron oxide by oxidation of the metallic silicon, producing metallic iron and silicon oxides.   
     
     
         2 . The method of  claim 1 , further comprising deoxygenating a second ore to produce the metallic silicon and an oxygen gas stream. 
     
     
         3 . The method of  claim 2 , wherein a source of the first ore is the source of the second ore. 
     
     
         4 . The method of  claim 1 , further comprising separating the metallic iron from the silicon oxides. 
     
     
         5 . The method of  claim 4 , wherein separating the metallic iron from the silicon oxides comprises a process selected from the group consisting of magnetic separation, electrostatic separation, physical separation based on differences in particle size, physical separation based on differences in shape, physical separation based on differences in density, and vacuum vaporization of silicon monoxide out of the metallic iron. 
     
     
         6 . The method of  claim 1 , further comprising producing heat by reducing the iron oxide by oxidation of the metallic silicon. 
     
     
         7 . The method of  claim 6 , further comprising transferring the heat to Lunar habitats, transferring the heat to Lunar unit operations, converting the heat to electricity, or combinations thereof. 
     
     
         8 . The method of  claim 6 , further comprising transferring the heat for use during the Lunar night. 
     
     
         9 . The method of  claim 6 , further comprising separating silicon monoxide from the metallic iron by vacuum vaporization of the silicon monoxide, and wherein the silicon monoxide is refined to a silicon product, a silicon dioxide product, or both. 
     
     
         10 . The method of  claim 1 , further comprising heating the slag and the first ore to initiate reduction of the iron oxide. 
     
     
         11 . The method of  claim 10 , wherein heating the slag and the first ore comprises beneficiating the slag and the first ore until frictional heat initiates reduction. 
     
     
         12 . A system for producing metallic iron, comprising:
 a crucible to mix a slag and a first ore to form a first mixture, the slag comprising metallic silicon and the first ore comprising iron oxide; and either:   a heater to heat the crucible to a temperature to initiate the iron oxide reduction by the metallic silicon, producing metallic iron and silicon oxides; or   a heater to heat the slag to a molten temperature such that mixing the slag and the first ore initiates iron oxide reduction by the metallic silicon, producing metallic iron and silicon oxides.   
     
     
         13 . The system of  claim 12 , further comprising a separator to pretreat the slag by removing non-metals from the slag. 
     
     
         14 . The system of  claim 12 , further comprising operating the crucible in vacuum on the Lunar surface and wherein off-gases from the first mixture leave the first mixture into the vacuum. 
     
     
         15 . The system of  claim 14 , further comprising a condenser to recover the off-gases, wherein the off-gases are selected from the group consisting of water, phosphorus, phosphorus-containing compounds, sulfur, sulfur-containing compounds, metals, metal oxides, silicon monoxide, mercury, and mercury containing compounds. 
     
     
         16 . The system of  claim 12 , wherein the heater is disengaged after the reduction initiates as the reduction produces excess heat. 
     
     
         17 . The system of  claim 12 , further comprising a reduction unit to deoxygenate a second ore to produce the slag and an oxygen gas stream. 
     
     
         18 . The system of  claim 12 , wherein a pre-heater moltens the silicon metal, moltens the first ore, or moltens both before mixing the silicon metal with the first ore. 
     
     
         19 . The system of  claim 18 , further comprising a vent to Lunar vacuum to provide vacuum to separate silicon monoxide from the metallic iron by vacuum vaporization of the silicon monoxide, and further comprising a refining unit to refine the silicon monoxide to a silicon product, a silicon dioxide product, or both. 
     
     
         20 . A system for producing metallic iron, comprising:
 a separator to separate a slag into an oxide residue and a metal product;   a crucible to mix the metal product and a first ore, the metal product comprising metallic silicon and the first ore comprising iron oxide; and either:   a heater to heat the crucible to a temperature to initiate the iron oxide reduction by the metallic silicon, producing metallic iron and silicon oxides; or   a heater to molten the metal product, the first ore, or both before mixing, whereby mixing the slag and the first ore initiates iron oxide reduction by the metallic silicon, producing metallic iron and silicon oxides.