Metal oxide smelting method

Abstract

Provided is a smelting method in which, for example, a metal oxide such as a nickel oxide ore including nickel oxide is used as a source material and is reduced with a carbonaceous reducing agent to obtain a reduced product, with which method efficient processing can be achieved. This metal oxide smelting method is, for example, a nickel oxide ore smelting method. Specifically, the method includes a reduction process step that has: a drying step in which a mixture that was obtained by mixing a metal oxide and a carbonaceous reducing agent is dried; a preheating step in which the dried mixture is preheated; a reduction step in which the preheated mixture is reduced using a rotary hearth furnace, said rotary hearth having a hearth that rotates and not having a partition structure in an interior; and a cooling step in which the obtained reduced product is cooled.

1 . A metal oxide smelting method comprising a reduction treatment step including:
 a drying step in which a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent is dried;   a preheating step in which the dried mixture is preheated;   a reduction step in which the preheated mixture is reduced using a rotary hearth furnace, the rotary hearth having a hearth that rotates and not having a partition structure in an interior; and   a cooling step in which the obtained reduced product is cooled.   
     
     
         2 . The metal oxide smelting method according to  claim 1 , wherein the reduced product obtained through the reduction step is subjected to a temperature maintenance step in which the reduced product is maintained at a prescribed temperature in the rotary hearth furnace, and after maintained for a prescribed time, the reduced product is supplied to the cooling step. 
     
     
         3 . The metal oxide smelting method according to  claim 2 , wherein a treatment in the reduction step and a treatment in the temperature maintenance step are performed using the same rotary hearth furnace. 
     
     
         4 . The metal oxide smelting method according to  claims 2 , wherein the reduced product is maintained at a temperature of 1300° C. or higher and 1500° C. or lower in the temperature maintenance step. 
     
     
         5 . The metal oxide smelting method according to  claim 1 , wherein in the reduction step, reduction is performed while a reducing temperature is set to 1200° C. or higher and 1500° C. or lower. 
     
     
         6 . The metal oxide smelting method according to  claim 5 , wherein in the reduction step, the mixture is reduced at reducing temperatures of two steps,
 the reducing temperature at the first step is 1200° C. or higher and 1450° C. or lower, and   the reducing temperature at the second step is 1300° C. or higher and 1500° C. or lower.   
     
     
         7 . The metal oxide smelting method according to  claim 6 , wherein the rotary hearth furnace includes a plurality of heating sources, and a temperature distribution inside the rotary hearth furnace is controlled by controlling an amount of energy supplied to each heating source. 
     
     
         8 . The metal oxide smelting method according to  claim 1 , wherein the mixture to be dried in the drying step is obtained through
 a mixing treatment step in which at least a metal oxide and a carbonaceous reducing agent are mixed to obtain a mixture, and   a pretreatment step in which a treatment of forming the obtained mixture into a lump product or a treatment of filling the mixture in a prescribed container is performed.   
     
     
         9 . The metal oxide smelting method according to  claim 1 , further comprising a separating step in which the reduced product cooled in the cooling step in the reduction treatment step is separated into a metal and slag and the metal is recovered. 
     
     
         10 . The metal oxide smelting method according to  claim 1 , wherein the metal oxide is nickel oxide ore. 
     
     
         11 . The metal oxide smelting method according to  claim 1 , wherein the reduced product contains ferronickel. 
     
     
         12 . The metal oxide smelting method according to  claim 2 , wherein in the reduction step, reduction is performed while a reducing temperature is set to 1200° C. or higher and 1500° C. or lower. 
     
     
         13 . The metal oxide smelting method according to  claim 3 , wherein in the reduction step, reduction is performed while a reducing temperature is set to 1200° C. or higher and 1500° C. or lower. 
     
     
         14 . The metal oxide smelting method according to  claim 4 , wherein in the reduction step, reduction is performed while a reducing temperature is set to 1200° C. or higher and 1500° C. or lower. 
     
     
         15 . The metal oxide smelting method according to  claim 12 , wherein in the reduction step, the mixture is reduced at reducing temperatures of two steps,
 the reducing temperature at the first step is 1200° C. or higher and 1450° C. or lower, and   the reducing temperature at the second step is 1300° C. or higher and 1500° C. or lower.   
     
     
         16 . The metal oxide smelting method according to  claim 15 , wherein the rotary hearth furnace includes a plurality of heating sources, and a temperature distribution inside the rotary hearth furnace is controlled by controlling an amount of energy supplied to each heating source. 
     
     
         17 . The metal oxide smelting method according to  claim 2 , wherein the mixture to be dried in the drying step is obtained through
 a mixing treatment step in which at least a metal oxide and a carbonaceous reducing agent are mixed to obtain a mixture, and   a pretreatment step in which a treatment of forming the obtained mixture into a lump product or a treatment of filling the mixture in a prescribed container is performed.   
     
     
         18 . The metal oxide smelting method according to  claim 2 , further comprising a separating step in which the reduced product cooled in the cooling step in the reduction treatment step is separated into a metal and slag and the metal is recovered. 
     
     
         19 . The metal oxide smelting method according to  claim 2 , wherein the metal oxide is nickel oxide ore. 
     
     
         20 . The metal oxide smelting method according to  claim 2 , wherein the reduced product contains ferronickel.