Method for Manufacturing an Austenitic Stainless Steel from a Nickel Laterite Ore and a Chromite Ore

Abstract

A method for manufacturing an austenitic stainless steel from a nickel laterite ore and a chromite ore includes the steps of determining a nickel content of the nickel laterite ore; processing the nickel laterite ore into a nickel-containing precursor based on the determination; obtaining a molten ferrochrome from the chromite ore; transferring the nickel-containing precursor into a converter, and hot charging the molten ferrochrome into the converter to obtain a molten stainless steel; and charging the molten stainless steel into a continuous casting machine to obtain a stainless steel slab.

We claim: 
     
         1 . A method for manufacturing an austenitic stainless steel from a nickel laterite ore and a chromite ore, said method comprising steps of:
 a) crushing, screening, and blending the nickel laterite ore, followed by roasting the nickel laterite ore in a rotary kiln to remove free water and crystallization water along with charging a reducing agent into the rotary kiln to obtain a calcine, and smelting the calcine in an electric furnace to obtain a molten ferronickel;   b) sintering the chromite ore in a sintering device to obtain a sintered chromite ore, followed by smelting the sintered chromite ore along with a coke particle in another electric furnace to obtain a molten ferrochrome;   c) hot charging the molten ferronickel and the molten ferrochrome into a converter to obtain a molten stainless steel; and   d) charging the molten stainless steel into a continuous casting machine to obtain a stainless steel slab.   
     
     
         2 . The method for manufacturing an austenitic stainless steel as claimed in  claim 1 , wherein, in step (a), a roasting temperature of the rotary kiln ranges from 800° C. to 950° C. and a tapping temperature of the molten ferronickel ranges from 1400° C. to 1500° C. 
     
     
         3 . The method for manufacturing an austenitic stainless steel as claimed in  claim 1 , further comprising steps of pressing the chromite ore with a coke powder in a ball press machine to form chromite pellets and drying the chromite pellets to remove water prior to step b). 
     
     
         4 . The method for manufacturing an austenitic stainless steel as claimed in  claim 1 , wherein the sintered chromite ore has a particle size less than 30 mm. 
     
     
         5 . The method for manufacturing an austenitic stainless steel as claimed in  claim 1 , further comprising a step of drying the nickel laterite ore in a drying kiln to remove a portion of the free water prior to step a). 
     
     
         6 . A method for manufacturing an austenitic stainless steel from a nickel laterite ore and a chromite ore, said method comprising steps of:
 a) crushing the nickel laterite ore and pulping the nickel laterite ore with water to form a pulp material, followed by agitating the pulp material with a sulfuric acid solution under a high pressure atmosphere to form a mixture, filtering a leach solution containing nickel and cobalt out of the mixture, separating the leach solution by solvent extraction into an extraction solution containing nickel and an anti-extraction solution containing cobalt, and electrolyzing the extraction solution and the anti-extraction solution to obtain pure nickel and pure cobalt, respectively;   b) sintering the chromite ore in a sintering device to obtain a sintered chromite ore, followed by smelting the sintered chromite ore in an electric furnace to obtain a molten ferrochrome;   c) transferring the pure nickel into a converter, and hot charging the molten ferrochrome into the converter to obtain a molten stainless steel; and   d) charging the molten stainless steel into a continuous casting machine to obtain a stainless steel slab.   
     
     
         7 . The method for manufacturing an austenitic stainless steel as claimed in  claim 6 , wherein, in step (a), a solid-liquid ratio of the nickel laterite ore to the sulfuric acid solution is about 1:4, and the pulp material is agitated with the sulfuric acid solution under a pressure ranging from 4 to 5 MPa and at a temperature ranging from 250° C. to 300° C. 
     
     
         8 . The method for manufacturing an austenitic stainless steel as claimed in  claim 6 , further comprising steps of pressing the chromite ore with a coke powder in a ball press machine to form chromite pellets and drying the chromite pellets to remove water prior to step b). 
     
     
         9 . The method for manufacturing an austenitic stainless steel as claimed in  claim 6 , wherein, in step (b), the sintered chromite ore has a particle size less than 30 mm. 
     
     
         10 . A method for manufacturing an austenitic stainless steel from a nickel laterite ore and a chromite ore, said method comprising steps of:
 a) determining whether a nickel content of the nickel laterite ore is less than 1.5 wt % based on total weight of the nickel laterite ore;   b) processing the nickel laterite ore into a nickel-containing precursor based on the determination made in step a);   c) sintering the chromite ore in a sintering device to obtain a sintered chromite ore, followed by smelting the sintered chromite ore along with a coke particle in an electric furnace to obtain a molten ferrochrome;   d) transferring the nickel-containing precursor into a converter, and hot charging the molten ferrochrome into the converter to obtain a molten stainless steel; and   e) charging the molten stainless steel into a continuous casting machine to obtain a stainless steel slab.   
     
     
         11 . The method for manufacturing an austenitic stainless steel as claimed in  claim 10 , wherein, when the nickel content of the nickel laterite ore is determined to be not less than 1.5 wt %, the nickel-containing precursor is a molten ferronickel, and step b) is conducted by crushing, screening, and blending the nickel laterite ore, followed by roasting the nickel laterite ore in a rotary kiln to remove free water and crystallization water along with charging a reducing agent into the rotary kiln to obtain a calcine, and smelting the calcine in another electric furnace to obtain the molten ferronickel. 
     
     
         12 . The method for manufacturing an austenitic stainless steel as claimed in  claim 11 , wherein in step b), a roasting temperature of the rotary kiln ranges from 800° C. to 950° C. and a tapping temperature of the molten ferronickel ranges from 1400° C. to 1500° C. 
     
     
         13 . The method for manufacturing an austenitic stainless steel as claimed in  claim 11 , further comprising a step of drying the nickel laterite ore in a drying kiln to remove a portion of the free water prior to step b). 
     
     
         14 . The method for manufacturing an austenitic stainless steel as claimed in  claim 10 , wherein, when the nickel content of the nickel laterite ore is determined to be less than 1.5 wt %, the nickel-containing precursor is pure nickel, and step b) is conducted by crushing the nickel laterite ore and pulping the nickel laterite ore with water to form a pulp material, followed by agitating the pulp material with a sulfuric acid solution under a high pressure atmosphere to form a mixture, filtering a leach solution containing nickel and cobalt out of the mixture, separating the leach solution by solvent extraction into an extraction solution containing nickel and an anti-extraction solution containing cobalt, and electrolyzing the extraction solution and the anti-extraction solution to obtain pure nickel and pure cobalt, respectively. 
     
     
         15 . The method for manufacturing an austenitic stainless steel as claimed in  claim 14 , wherein in step b), a solid-liquid ratio of the nickel laterite ore to the sulfuric acid solution is about 1:4, and the pulp material is agitated with the sulfuric acid solution under a pressure ranging from 4 to 5 MPa and at a temperature ranging from 250° C. to 300° C. 
     
     
         16 . The method for manufacturing an austenitic stainless steel as claimed in  claim 10 , wherein
 when the nickel content of the nickel laterite ore is determined to be not less than 1.5 wt %, the nickel-containing precursor is a molten ferronickel, and step b) is conducted by crushing, screening, and blending the nickel laterite ore, followed by roasting the nickel laterite ore in a rotary kiln to remove free water and crystallization water along with charging a reducing agent into the rotary kiln to obtain a calcine, and smelting the calcine in another electric furnace to obtain the molten ferronickel;   when the nickel content of the nickel laterite ore is determined to be less than 1.5 wt %, the nickel-containing precursor is pure nickel, and step b) is conducted by crushing the nickel laterite ore and pulping the nickel laterite ore with water to form a pulp material, followed by agitating the pulp material with a sulfuric acid solution under a high pressure atmosphere to form a mixture, filtering a leach solution containing nickel and cobalt out of the mixture, separating the leach solution by solvent extraction into an extraction solution containing nickel and an anti-extraction solution containing cobalt, and electrolyzing the extraction solution and the anti-extraction solution to obtain pure nickel and pure cobalt, respectively; and   in step (d), the nickel-containing precursor transferred into the converter includes the molten ferronickel and the pure nickel.   
     
     
         17 . The method for manufacturing an austenitic stainless steel as claimed in  claim 10 , further comprising steps of pressing the chromite ore with a coke powder in a ball press machine to form chromite pellets and drying the chromite pellets to remove water prior to step c). 
     
     
         18 . The method for manufacturing an austenitic stainless steel as claimed in  claim 10 , wherein in step c), the sintered chromite ore has a particle size less than 30 mm.