Enrichment of iron from bauxite waste in chemical looping combustion

Abstract

A method of recovering enriched iron fines from bauxite waste includes calcining particles of bauxite waste to form oxygen carrier particles, subjecting the oxygen carrier particles to chemical looping combustion at a temperature of about 950° C.-1,050° C. for energy production and to produce the enriched iron fines as a by-product from the oxygen carrier particles via natural attrition and collecting the enriched iron fines.

What is claimed: 
     
         1 . A method of recovering enriched iron fines from bauxite waste, comprising:
 calcining particles of bauxite waste to form oxygen carrier particles;   subjecting the oxygen carrier particles to chemical looping combustion at a temperature of about 950° C.-1,050° C. to produce (a) energy and (b) the enriched iron fines as a by-product from the oxygen carrier particles via natural attrition; and   collecting the enriched iron fines.   
     
     
         2 . The method of  claim 1 , wherein the calcining of the particles of bauxite waste includes heating the particles of bauxite waste to a predetermined temperature for a predetermined period of time needed to form the oxygen carrier particles. 
     
     
         3 . The method of  claim 2 , wherein the subjecting of the oxygen carrier particles to chemical looping combustion includes cyclically reducing and oxidizing the oxygen carrier particles to produce the enriched iron fines while generating energy. 
     
     
         4 . The method of  claim 3 , wherein (a) the reducing includes subjecting the oxygen carrier particles in a reactor bed to the presence of a reducing agent, and (b) the oxidizing includes subjecting the oxygen carrier particles in the reactor bed to heating in the presence of an oxidizing agent. 
     
     
         5 . The method of  claim 4 , wherein the reducing agent is carbon monoxide (CO), H 2 , carbon, coal, natural gas or other fuels including solid and gas fuels. 
     
     
         6 . The method of  claim 4 , further including purging the reactor bed with an inert gas between reducing and oxidizing. 
     
     
         7 . The method of  claim 4 , wherein the oxidizing agent is air or oxygen mixed with a type of inert gas at greater than 4 vol %. 
     
     
         8 . The method of  claim 7 , wherein the collecting of the iron enriched fines is done by using a gas-solid separation device, a baghouse, an electrostatic precipitator, a cyclone or a combination thereof. 
     
     
         9 . The method of  claim 4 , wherein the heating or cooling via thermal cycle of the oxygen carrier particles during the reducing and the oxidizing cycles is to a temperature of between about 950° C. and about 1050° C. 
     
     
         10 . The method of  claim 1 , wherein (a) the reducing includes subjecting the oxygen carrier particles in a reactor bed to heating, cooling or maintaining temperature in the presence of a reducing agent, and (b) the oxidizing includes subjecting the oxygen carrier particles in the reactor bed to heating in the presence of an oxidizing agent. 
     
     
         11 . The method of  claim 10 , wherein the heating of the oxygen carrier particles during the reducing and the oxidizing cycles is to a temperature of between about 950° C. and about 1050° C. 
     
     
         12 . The method of  claim 1 , wherein the subjecting of the oxygen carrier particles to chemical looping combustion includes cyclically reducing and oxidizing the oxygen carrier particles to produce the enriched iron fines while generating energy. 
     
     
         13 . The method of  claim 12 , wherein the subjecting of the oxygen carrier particles to chemical looping combustion includes cyclically reducing and oxidizing the oxygen carrier particles to produce the enriched iron fines while generating energy. 
     
     
         14 . The method of  claim 13 , wherein (a) the reducing includes subjecting the oxygen carrier particles in a reactor bed to the presence of a reducing agent, and (b) the oxidizing includes subjecting the oxygen carrier particles in the reactor bed to heating in the presence of an oxidizing agent. 
     
     
         15 . The method of  claim 14 , wherein the reducing agent is carbon monoxide (CO), H 2 , carbon, coal, natural gas or other fuels including solid and gas fuels. 
     
     
         16 . The method of  claim 14 , wherein the oxidizing agent is air 
     
     
         17 . The method of  claim 16 , wherein the collecting of the iron enriched fines is done by gas-solid separation devices such as baghouse, ESP, or cyclone. 
     
     
         18 . The method of  claim 14 , wherein the heating or cooling via thermal cycle of the oxygen carrier particles during the reducing and the oxidizing cycles is to a temperature of between about 950° C. and about 1050° C. 
     
     
         19 . A method of recovering enriched iron fines from bauxite waste, comprising:
 calcining particles of bauxite waste to form oxygen carrier particles;   subjecting the oxygen carrier particles to chemical looping combustion at a temperature above 1000° C. to produce (a) a spent flue gas and (b) the enriched iron fines as a by-product from the oxygen carrier particles via natural attrition;   collecting the enriched iron fines from the spent flue gas; and   using the spent flue gas to generate steam for power generation.   
     
     
         20 . A method of recovering enriched iron fines from bauxite waste, comprising:
 subjecting the oxygen carrier particles made from bauxite waste to chemical looping combustion at a temperature above 1000° C. to produce (a) a spent flue gas and (b) the enriched iron fines as a by-product from the oxygen carrier particles via natural attrition;   collecting the enriched iron fines; and   using the spent flue gas, following the collecting of the enriched iron fines, to generate steam for power generation.