Processing of metal chloride solutions and method and apparatus for producing direct reduced iron

Abstract

A process and apparatus for regeneration of acid and metal from spent acid liquors includes the steps of, optionally, concentrating ( 110 ) the liquor to a concentrated liquor or solid, pyrohydrolysing ( 114 ) to regenerate the acid and form metal oxide pellets, and reducing the oxide to metal in a two stage reduction reactor ( 116, 118 ) using a partially combusted fuel as reducing agent. Also disclosed is a two-stage reduction process and reactor for production of direct reduced iron (DRI) from iron oxide ores or wastes, including a first stage ( 416 ) in which the oxide feed is contacted with a fuel and a sub-stoichiometric amount of an oxygen source to produce a lower oxidation state oxide, and a second stage ( 418 ) in which the lower oxidation stage oxide is contacted with off-gases from the first stage to produce iron metal.

1 . A process of regeneration of acid and metal from spent acid liquor containing metal chloride in aqueous solution, including the steps of, in sequence:
 (a) optionally, concentrating the liquor to form a liquor concentrate or solidifying the liquor concentrate to form a solid metal chloride;   (b) pyrohydrolysing the liquor, concentrated liquor or solid metal chloride in a reactor to regenerate the acid and form a metal oxide; and   (c) reducing the metal oxide to metal.   
   
   
       2 . A process according to  claim 1 , wherein the metal is iron or is predominantly iron. 
   
   
       3 . A process according to  claim 1 , wherein the reduction step is conducted as a two stage co-current reduction reaction. 
   
   
       4 . A process according to  claim 3 , wherein a first stage reduction reaction to a lower oxidation state oxide uses a partially combusted hydrocarbon fuel as a reducing agent. 
   
   
       5 . A process according to  claim 4 , wherein the first reduction stage is conducted in a first fluid bed reduction reactor in which the metal oxide is contacted with the fuel and a sub-stoichiometric amount of oxygen. 
   
   
       6 . A process according to  claim 4 , wherein said oxygen is provided to said first reduction stage as air. 
   
   
       7 . A process according to  claim 4 , wherein off-gas of the first reduction stage is used as the reducing agent for the second reduction for the second stage. 
   
   
       8 . A process according to  claim 3 , wherein off-gas from the second stage reduction reactor is oxidized to provide energy for the concentration or pyrohydrolysis steps of the process. 
   
   
       9 . A process according to  claim 1 , wherein off-gases from the oxide pellet metallising stage are used for the evaporation of the metal chloride liquor. 
   
   
       10 . A process according to  claim 2 , further including the step of adding iron oxide to the aqueous solution of metal chloride. 
   
   
       11 . A process for treatment of a metal oxide, including the steps of:
 (a) contacting the metal oxide feed with a reducing agent comprising a fuel and a sub-stoichiometric amount of an oxygen source, in a first stage reduction to form a lower oxidation state oxide; and   (b) feeding the lower oxidation state oxide formed by the first stage reduction and off-gases from the first stage to a second reduction stage wherein the lower oxidation state oxide is reduced to the metal.   
   
   
       12 . A process according to  claim 11 , wherein said metal is iron. 
   
   
       13 . A process according to  claim 12 , wherein lower oxidation state oxide is predominantly FeO. 
   
   
       14 . A process according to  claim 10 , wherein the first and second stages reduction reactions are carried out in respective first and second fluid bed reduction reaction chambers. 
   
   
       15 . A process according to  claim 14 , including transporting said lower oxidation state oxide from the first reaction chamber to the second reaction chamber by means of an inert gas stream. 
   
   
       16 . A process according to  claim 12 , wherein said metal oxide feed is an iron ore. 
   
   
       17 . A process according to  claim 11 , wherein said metal oxide feed is a pelletised metal oxide formed by pyrohydrolytic regeneration of a spent acid liquor containing a metal halide 
   
   
       18 . A process according to  claim 12 , wherein said metal halide is iron chloride.