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US 3,998,625 AGranted
Desulfurization method
AssigneeJones & Laughlin Steel Corporation
InventorPeter J. Koros
Life of this patent
Estimating the term…
Abstract
Desulfurization of molten ferrous metals such as pig iron is facilitated through the injection of a particulate fluidized mixture of non-oxidizing material and magnesium-containing reactive material by in-line mixing in a conveying line and consequent sub-surface injection. The amount of the contained magnesium, injection time, and contained magnesium injection rate are controlled to maximize process efficiency.
Claims12
A method for desulfurizing molten ferrous metal, comprising:
- a. Forming a fluidized first mixture of a particulate material that is non-oxidizing with respect to molten ferrous metal and is selected from the group consisting of lime, metallurgical slag, alumina, fly ash, silica, and calcium carbide and sized so that about 80 percent of its particles are smaller than about 100 microns with a non-oxidizing carrier gas;
- b. Introducing particulate magnesium-containing material sized so that substantially all of its particles are below about 300 microns into said first mixture to form a second mixture;
- and then
- c. Transporting and injecting the second mixture beneath the surface of sulfur-containing molten ferrous metal so as to remove sulfur from said ferrous metal, said non-oxidizing particulate material and said magnesium-containing material injected at a rate of from about 90 to 300 lbs./min. and from about 4 to 30 lbs. of contained magnesium/min., respectively, and further controlling injection of said magnesium-containing mixture by reducing the rate of injection of the magnesium-containing material in response to sulfur content of said molten ferrous metal in accordance with the following relationship:
- ##EQU4## where, F.sub.s = Sulfur content at end of process,
- A = constant,
- B = constant,
- R = Lbs. Mg/min.,
- C = constant,
- I.sub.s = Sulfur content at time calculation made during process,
- T = Lbs. Mg/ton of molten ferrous metal.
8 more elements
A method for desulfurizing molten ferrous metal, comprising:
- a. Forming a fluidized first mixture of a particulate material that is non-oxidizing with respect to molten ferrous metal and is selected from the group consisting of lime, metallurgical slag, alumina, fly ash, silica, and calcium carbide and sized so that about 80 percent of its particles are smaller than about 100 microns with a non-oxidizing carrier gas;
- b. Introducing particulate magnesium-containing material sized so that substantially all of its particles are below about 300 microns into said first mixture to form a second mixture;
- and then
- c. Transporting and injecting the second mixture beneath the surface of sulfur-containing molten ferrous metal so as to remove sulfur from said ferrous metal, said non-oxidizing particulate material and said magnesium-containing material injected at a rate of from about 90 to 300 lbs.min. and from about 4 to 30 lbs. of contained magnesium/min., respectively;
- and
- d. reducing the rate of magnesium-containing material injection during the injection step in response to sulfur content of said molten ferrous metal so as to minimize the creation of substantial amounts of vaporized magnesium above the surface of said molten ferrous metal.
3 more elements
Dependencies are inferred from the claim text.