Industrial process

Abstract

A process of producing a metal from the corresponding metal halide by reaction of the metal halide with a reducing agent to form the metal and a halide of the reducing agent, the reaction taking place at elevated temperature and at atmospheric pressure in a reactor comprising a fluidised bed of seed particles of the metal, which process comprises: injecting into the reactor an inert gas at a rate and in an amount effective to form a fluidised bed of the seed particles and to ensure that unreacted reductant and the halide of the reducing agent do not condense in the reactor under the prevailing conditions of temperature and pressure; maintaining the maximum temperature in the reactor below the melting point of the metal; and delivering the metal halide and reducing agent into the fluidised bed in a manner that favours formation of the metal on the seed particles over formation of the metal by homogeneous gas phase reaction between the metal halide and reducing agent.

1 . A process of producing a metal from the corresponding metal halide by reaction of the metal halide with a reducing agent to form the metal and a halide of the reducing agent, the reaction taking place at elevated temperature and at atmospheric pressure in a reactor comprising a fluidised bed of seed particles of the metal, which process comprises:
 injecting into the reactor an inert gas at a rate and in an amount effective to form a fluidised bed of the seed particles and to ensure that unreacted reductant and the halide of the reducing agent do not condense in the reactor under the prevailing conditions of temperature and pressure;   maintaining the maximum temperature in the reactor below the melting point of the metal; and   delivering the metal halide and reducing agent into the fluidised bed in a manner that favours formation of the metal on the seed particles over formation of the metal by homogeneous gas phase reaction between the metal halide and reducing agent.   
   
   
       2 . A process according to  claim 1 , which comprises promoting heterogeneous phase reaction on the surface of the seed particles making up the fluidised bed by delivering the reactants into the fluidised bed in such a way that one of the reactants is present and available for reaction at the surface of the seed particles before there is any contact of this reactant with the co-reactant. 
   
   
       3 . A process according to  claim 1 , wherein the reactants are delivered into the fluidised bed in gaseous/vapour form and one of the reactants is absorbed by or impregnates the seed particles prior to contact with the co-reactant. 
   
   
       4 . A process according to  claim 3 , wherein the metal halide which becomes associated with the seed particles. 
   
   
       5 . A process according to  claim 3 , wherein the reactants are delivered into separate regions of the fluidised bed. 
   
   
       6 . A process according to  claim 5 , wherein points of delivery of the reactants and flow of the seed particles are such that the seed particles come into contact with one of the reactants, thereby becoming associated with it, with subsequent flow of the particles into a region where the other reactant is present with reaction between the reactants taking place at the surface of the seed particles with metal being deposited on the surface of the particles. 
   
   
       7 . A process according to  claim 3 , wherein the reactants are delivered using individual injection nozzles for each reactant. 
   
   
       8 . A process according to  claim 3 , wherein the reactants are delivered using an injection nozzle having concentric outlets for the reactants. 
   
   
       9 . A process according to  claim 8 , wherein premature contact of the reactants is prevented by injecting inert gas between adjacent streams of reactants. 
   
   
       10 . A process according to  claim 9 , wherein the inert gas is delivered through an annular conduit provided between central and annular conduits through which the reactants are delivered. 
   
   
       11 . A process according to  claim 1 , wherein one of the reactants is present in the fluidised bed as a liquid and this reactant wets the surface of the seed particles prior to contacting the co-reactant as a result of particulate flow. 
   
   
       12 . A process according to  claim 1 , wherein the seed particles are formed of the same metal it is desired to produce by the reduction-reaction. 
   
   
       13 . A process according to  claim 1 , wherein coarsened particles are removed from the reactor through a self-regulating process based on the particle size and fluidisation conditions. 
   
   
       14 . A process according to  claim 1 , wherein the reduction reaction is exothermic and at least one of the reactants is delivered into the fluidised bed as a solid or liquid with subsequent phase change of the at least one reactant as a result of the temperature in the fluidised bed in order to moderate the temperature within the reactor as the reduction reaction proceeds. 
   
   
       15 . A process according to  claim 1 , for producing titanium by reduction of titanium tetrachloride. 
   
   
       16 . A process according to  claim 15 , wherein the reductant is magnesium. 
   
   
       17 . A process according to  claim 16 , wherein the titanium tetrachloride and magnesium are delivered into the fluidised bed as gases. 
   
   
       18 . A process according to  claim 16 , wherein magnesium is present in the fluidised bed in the form of a molten liquid, wherein titanium tetrachloride is delivered into the fluidised bed as a gas, and wherein the magnesium wets the seed particles prior to contacting the titanium tetrachloride. 
   
   
       19 . A process according to  claim 18 , wherein the magnesium is delivered into the reactor as a solid with the temperature being sufficient to melt the magnesium immediately. 
   
   
       20 . An apparatus for carrying out the process of  claim 1 , which comprises a fluidised bed reactor that is adapted for delivery into the fluidised bed of metal halide and reducing agent in a manner that favours formation of the metal on seed particles of the fluidised bed over formation of the metal by homogeneous gas phase reaction between the metal halide and reducing agent. 
   
   
       21 . An apparatus according to  claim 20 , comprising an injection nozzle for delivery of gaseous reactants into the fluidised bed, the injection nozzle comprising concentric outlets for the reactants. 
   
   
       22 . An apparatus according to  claim 21 , wherein the injection nozzle comprises an annular conduit for delivery of inert gas, the annular conduit being provided between central an annular conduits for the reactants. 
   
   
       23 . An apparatus according to  claim 20 , comprising a spouted fluidised bed reactor adapted for the delivery of gaseous metal halide and heated inert gas at the base of the fluidised bed and a separate inlet for delivery of solid reductant into the reactor, the inlet being provided in a wall of the reactor above the base of the fluidised bed.