Melting of NI laterite in making NI alloyed iron or steel

Details Melting of NI laterite in making NI alloyed iron or steel Melting of NI laterite in making NI alloyed iron or steel

1996-12-04

1998-05-12

Simmons, David A.

Specialized metallurgical processes, compositions for use therei

Processes

Producing or treating free metal

75560, 75507, 75416, 75414, 75501, 75540, 75546, 75547, 420 34, 420 43, 420 50, 420 55, 420 62, C21C 500

Patent

active

057499390

ABSTRACT:
A multiple stage process for obtaining Ni units from Ni laterite ores and sulfur-bearing Ni concentrates during production of nickel-alloyed iron, nickel-alloyed steel or nickel-alloyed stainless steel in a reactor equipped with top- and bottom-blowing means. Dried Ni laterite ore is charged into an iron/slag bath mixture containing dissolved carbon and a metalloid reductant such as aluminum or silicon. The laterite ore is melted while heat is generated by oxidation of the metalloid and carbon in the reactor. After the laterite ore is melted, top-blowing of pure oxygen and bottom-blowing of an oxygen-containing gas are ceased. Bottom injection of an inert stirring gas is begun. A sulfur-bearing Ni concentrate and aluminum are added to the bath. Sulfur from the sulfur-bearing Ni concentrate is transferred to and held within the slag produced from the laterite ore by controlling slag composition and temperature, degree of mixing of the iron/slag bath mixture by the inert gas and the carbon/metalloid concentration in the bath mixture. The sulfur-containing slag then is discharged from the reactor and the iron bath mixture is decarburized and refined to alloy specification. The extent of desulfurization by the slag determines the amount of sulfur-bearing Ni concentrate that can be added to the bath for a given slag weight. Total slag weight throughout the process should be within the range of 200 to 300 kg slag/MT bath mixture, the temperature of the bath should be maintained between 1500.degree.-1700.degree. C., the slag basicity should be controlled between 1-3 and the compositions of Al.sub.2 O.sub.3 and MgO in the slag should be maintained between 10-25 wt. % and 10-20 wt. % respectively.

REFERENCES:
patent: 3847601 (1974-11-01), Itoh et al.
patent: 4001012 (1977-01-01), Rote et al.
patent: 5039480 (1991-08-01), Tanabe et al.
patent: 5047082 (1991-09-01), Tanabe et al.
patent: 5575829 (1996-11-01), Kundrat

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