Method and apparatus for reducing metalliferous material to a reduction product

Abstract

Disclosed is a method for reducing metalliferous material to a reduction product. Also disclosed is an apparatus for reducing metalliferous material to a reduction product.

1 . Method of reducing metalliferous material to a reduction product, the method comprising the steps of:
 providing a gaseous phase comprising gaseous CO by gasifying a carbon-containing compound using an oxygen containing gas flow;   providing the metalliferous material in a reaction chamber of a fluidized bed reactor;   providing said gaseous CO in the reaction chamber of the fluidized bed reactor and converting the gaseous CO into solid carbon and gaseous carbon dioxide, making the solid carbon precipitate onto the metalliferous material and/or onto the reduction product;   reducing at least partly the metalliferous material by the solid carbon to the reduction product thereby using the metalliferous material and/or the reduction product as promoter of the conversion of the gaseous CO into solid carbon and gaseous carbon dioxide;   discharging a final reduction product from the reaction chamber,   wherein the final reduction product is further reduced in an end stage reactor to a higher degree of reduction or metallization by a substantially solid-solid reaction between the solid carbon and the incompletely reduced portion of the reduction product.   
     
     
         2 . Method according to  claim 1 , wherein the final reduction product after discharging from the reaction chamber of the fluidized bed reactor has a degree of reduction of at least 50%. 
     
     
         3 . Method according to  claim 1 , wherein the reduction in the end stage reactor takes place in a non-inert atmosphere. 
     
     
         4 . Method according to  claim 1 , wherein a hot gas flow comprising gaseous CO is fed into the end stage reactor. 
     
     
         5 . Method according to  claim 1 , wherein a CO/CO 2  and/or oxygen containing gas is provided into the end stage reactor. 
     
     
         6 . Method according to  claim 1 , wherein the method is performed as a continuous process wherein the metalliferous material and gaseous CO are provided continuously or batchwise to the reaction chamber so as to continuously produce the reduction product, and wherein the final reduction product is discharged continuously or batchwise from said reaction chamber. 
     
     
         7 . Method according to  claim 1 , wherein the final reduction product has a degree of reduction of at least 50%, preferably at least 60%, more preferably at least 70%. 
     
     
         8 . Method according to  claim 1 , wherein the maximum temperature in the reaction chamber is 875° C. 
     
     
         9 . Method according to  claim 1 , wherein the promoter of the conversion of the gaseous CO into solid carbon and gaseous carbon dioxide also acts as promoter of the reduction of the metalliferous material. 
     
     
         10 . Method according to  claim 1 , wherein the metalliferous material is an iron compound, preferably iron ore. 
     
     
         11 . Method according to  claim 10 , wherein the iron ore is provided in the form of a fine ore, wherein the grain size of the ore is between 0.1 and 5000 μm. 
     
     
         12 . Method according to  claim 1  wherein the metalliferous material is a nickel-compound, a cobalt-compound, or mixtures thereof. 
     
     
         13 . Method according to  claim 1  wherein the metalliferous material is a mixture of at least two compounds of the group of compounds comprising a nickel-compound, a cobalt-compound, and an iron-compound. 
     
     
         14 . Method according to  claim 1 , wherein the gaseous CO is prepared by gasifying a carbon-containing compound using an oxygen containing gas flow. 
     
     
         15 . Method according to  claim 1 , wherein off-gas is discharged from the reaction chamber, and wherein at least part of the remaining gaseous CO and/or the CO 2  is separated from the off-gas for reintroduction of said remaining gaseous CO and/or CO 2  into the gasifier reaction chamber. 
     
     
         16 . Method according to  claim 1 , wherein off-gas is discharged from the reaction chamber, and wherein at least part of the remaining gaseous CO and/or the CO 2  is separated from the off-gas for preheating the gas flow before entry into the gasifier. 
     
     
         17 . Method according to  claim 1 , wherein the reduction of the metalliferous material by the solid carbon takes place in a circulating fluidized bed (CFB) reactor, said reactor comprising a riser part and a return leg, wherein the metalliferous material and the gaseous CO are provided into the riser part of the CFB, and wherein a gas stream comprising the gaseous CO moves the metalliferous material in a substantially upward direction through the riser part of the CFB, and wherein the conversion of the gaseous CO into solid carbon and gaseous carbon dioxide takes place at least partly during the substantially upward movement of the metalliferous material and the gaseous CO. 
     
     
         18 . Method according to  claim 17 , wherein the metalliferous material and the reduction product resulting from the reduction of the metalliferous material and the solid carbon are discharged into the return leg of the CFB and the metalliferous material and the reduction product and the solid carbon move in a substantially downward direction through the return leg of the CFB and wherein reduction of the metalliferous material and the reduction product by the solid carbon takes place at least partly in the return leg of the CFB. 
     
     
         19 . Method according to  claim 1 , wherein reduced metalliferous material having reached the desired degree of reduction is discharged from the reaction chamber as the final reduction product. 
     
     
         20 . Method according to  claim 1 , wherein the reduction of the metalliferous material takes place in a plurality of fluidized bed reactors wherein the final reduction product of a preceding fluidized bed reactor of the plurality of connected fluidized bed reactors is discharged and passed to a subsequent fluidized bed reactor of the plurality of connected fluidized bed reactors for further reducing to a still higher degree of reduction. 
     
     
         21 . Method according to  claim 20 , wherein the gaseous phases discharged from a said subsequent fluidized bed is discharged into a said preceding fluidized bed reactor for further processing. 
     
     
         22 . Method according to  claim 1 , wherein the fluidized bed is of the fast fluidization or pneumatic conveying type. 
     
     
         23 . Method according to  claim 1 , wherein the final reduction product is further reduced to a degree of metallization of at least 90% in the end stage reactor by a substantially solid-solid reaction between the solid carbon and the incompletely reduced portion of the reduction product. 
     
     
         24 . Method according to  claim 1 , wherein the final reduction product is treated to separate the metallic part from a non-metallic part comprising gangue or slag. 
     
     
         25 . Method according to  claim 1 , wherein the final reduction product is further processed by compacting the product into a compacted product. 
     
     
         26 . Method according to  claim 1 , wherein the metalliferous material comprises iron-oxygen compounds and zinc-oxygen compounds, the method comprising reduction of the iron-oxygen compounds according to  claim 1 , comprising reduction of the zinc-oxygen compound by solid carbon originating from the gaseous CO to zinc, vaporising the zinc, followed by a zinc recovery step optionally comprising condensation of the zinc from the gaseous states or comprising re-oxidation of the zinc and collection as zinc-oxygen compounds. 
     
     
         27 . Apparatus for reducing metalliferous material to a reduction product according to the method of  claim 1 , comprising:
 at least one fluidized bed reactor comprising a reaction chamber;   a gasifier for producing a gaseous phase comprising gaseous CO by gasifying a carbon-containing compound using an oxygen containing gas flow comprising an inlet for providing said oxygen containing gas, an inlet for providing the carbon-containing compound, an outlet for the gaseous phase comprising gaseous CO, and an optional outlet for solid waste materials comprising slag,   a first inlet to the reaction chamber for introducing the metalliferous material;   a second inlet for introducing the gaseous CO into the reaction chamber;   means for generating a fluidized bed comprising the metalliferous material and the gaseous CO in the reaction chamber;   means for obtaining a suitable temperature in the reaction chamber for enabling conversion of the gaseous CO into solid carbon and gaseous carbon dioxide, and precipitation of the solid carbon onto the metalliferous material and/or onto the reduction product, and for reducing the metalliferous material by the solid carbon for producing a reduction product;   means for directing at least a part of the constituents of the fluidized bed towards separation means for separating the reduction product from the fluidized bed and optionally means for directing the off-gas from the fluidized bed to recycling means;   a return part for returning at least part of the reduction product separated from the gas stream to the reaction chamber and an outlet for discharging the remaining reduction product from the reaction chamber as final reduction product;   an optional end stage reactor for further reducing the reduction product to a higher degree of reduction by a substantially solid-solid reaction of the solid carbon with the reduction product.   
     
     
         28 . Apparatus according to  claim 27 , wherein the fluidized bed reactor is a circulating fluidised bed comprising:
 a riser part for accommodating a substantially upward movement of the fluidized bed, the fluidized bed comprising the metalliferous material and the gaseous CO;   means for directing the constituents of the fluidized bed towards separation means upon reaching the top part of the riser part for separating the reduction product from the fluidized bed and means for directing the gaseous phases from the fluidized bed to recycling means and means for directing the reduction product to a return leg;   the return leg for accommodating a substantially downward movement of the reduction product;   means for discharging the off-gas from the fluidized bed for further processing;   means for returning at least part of the reduction product from the return leg to the reaction chamber, said means also comprising an outlet for discharging the final reduction product from the reaction chamber.   
     
     
         29 . Apparatus according to  claim 28 , wherein the means for returning at least part of the reduction product from the return leg to the reaction chamber is a loop seal. 
     
     
         30 . Apparatus according to  claim 27 , comprising a plurality of connected fluidized bed reactors wherein means are provided for transporting the final reduction product from a preceding fluidized bed of the plurality of connected fluidized bed reactors to the reaction chamber of a subsequent fluidized bed reactor of the plurality of connected fluidized bed reactors for further reduction of the final reduction product to a higher degree of reduction and/or wherein means are provided for providing the gaseous phases discharged from a said subsequent fluidized bed into a said preceding fluidized bed reactor. 
     
     
         31 . Apparatus according to  claim 30  wherein means are provided for operating a said subsequent fluidized bed reactor at a higher temperature than a said preceding fluidized bed reactor. 
     
     
         32 . Apparatus according to  claim 27 , wherein the apparatus is provided with a gasifier, for providing the gaseous CO, a plurality of connected circulating fluidized beds, each comprising a reaction chamber, for providing the reduction product, an end stage reactor of the bubbling fluidised bed type for further reducing the reduction product, wherein there is a continuous link between the gasifier, the circulating fluidized beds and the end stage reactor. 
     
     
         33 . Apparatus according to  claim 27 , comprising a recycling unit for recycling Zn and/or Pb and/or Cd from Zn and/or Pb and/or Cd containing metalliferous material, the unit comprising heating means for enabling reduction of the Zn-, Pb- and/or Cd-containing compounds by the solid carbon to metallic Zn, Pb and/or Cd and to evaporate the Zn, Pb and/or Cd to produce gaseous Zn, Pb and/or Cd. 
     
     
         34 . Apparatus according to  claim 33 , provided with
 condensation means for condensing and/or solidifying the gaseous Zn, Pb and/or Cd into liquid and/or solid Zn, Pb and/or Cd, or   oxidation means for oxidizing the gaseous Zn, Pb and/or Cd to zinc-oxygen compounds, lead-oxygen compounds and/or cadmium-oxygen compounds.   
     
     
         35 . A method comprising using the reduction product produced by the method of  claim 6  in a sponge iron process for production of hydrogen. 
     
     
         36 . Method according to  claim 1 , wherein a CO/CO 2  and/or oxygen containing gas is provided into the end stage reactor, wherein the CO/CO 2  containing gas is fresh syngas and/or recycled process gas and/or wherein the oxygen containing gas is air or technically pure oxygen. 
     
     
         37 . Method according to  claim 1 , wherein the maximum temperature in the reaction chamber is 800° C. 
     
     
         38 . Method according to  claim 1 , wherein the metalliferous material comprises iron ore. 
     
     
         39 . Method according to  claim 10 , wherein the iron ore is provided in the form of a fine ore, wherein the grain size of the ore is between 5 and 50 μm. 
     
     
         40 . Method according to  claim 1 , wherein the metalliferous material is a nickel-ore, a cobalt-ore, or mixtures thereof. 
     
     
         41 . Method according to  claim 17 , wherein the metalliferous material and the reduction product resulting from the reduction of the metalliferous material and the solid carbon are discharged into the return leg of the CFB and the metalliferous material and the reduction product and the solid carbon move in a substantially downward direction through the return leg of the CFB and wherein reduction of the metalliferous material and the reduction product by the solid carbon takes place substantially in the return leg of the CFB. 
     
     
         42 . Method according to  claim 1 , wherein the final reduction product is further reduced to a degree of metallization of at least 98% in the end stage reactor by a substantially solid-solid reaction between the solid carbon and the incompletely reduced portion of the reduction product, wherein the end stage reactor is a rotary kiln, a rotary hearth furnace or a fluidized bed reactor. 
     
     
         43 . Method according to  claim 1 , wherein the final reduction product is further processed by compacting the product into a compacted product by briquetting or by rolling into a rolled product. 
     
     
         44 . Method according to  claim 26 , comprising the condensation of the zinc from the gaseous states or the re-oxidation of the zinc and collection as zinc-oxygen compounds 
     
     
         45 . Apparatus according to  claim 27 , comprising the end stage reactor, wherein the end stage reactor is a rotary kiln, rotary hearth furnace or fluidized bed reactor. 
     
     
         46 . Apparatus according to  claim 30 , wherein means are provided for operating a said subsequent fluidized bed reactor at a higher temperature than a said preceding fluidized bed reactor, wherein any subsequent reactor operates at a higher temperature than any preceding fluidized bed reactor. 
     
     
         47 . Apparatus according to  claim 1 , wherein the apparatus is provided with an entrained flow gasifier, for providing the gaseous CO, a plurality of connected circulating fluidized beds, each comprising a reaction chamber, for providing the reduction product, an end stage reactor of the bubbling fluidised bed type for further reducing the reduction product wherein there is a continuous link between the gasifier, the circulating fluidized beds and the end stage reactor, wherein an overpressure of at least 2 bar exists in the apparatus.