Methods for producing improved steels by injecting iron containing by-products of an iron ore production process into liquid steel

Patent metadata

Field	Value
Publication number	US-2016326606-A1
Application number	US-201515109493-A
Country	US
Kind code	A1
Filing date	Jan 29, 2015
Priority date	Jan 31, 2014
Publication date	Nov 10, 2016
Grant date	—

Abstract

Disclosed herein are methods and compositions for producing improved steels comprising injecting iron containing by-products of an iron ore production process into a liquid steel, wherein the iron containing by-products of an iron ore production process further comprise direct reduced iron (DRI) fines. The resulting improved steel exhibits lower nitrogen content than one measured for a substantially identical reference composition produced in the absence of the direct reduced iron fines.

First claim

1 . A method for producing a steel, the method comprising:
a) providing a feed of a metallic scrap comprising steelmaking raw materials; b) introducing the feed of the metallic scrap comprising steelmaking raw materials into a furnace; c) bringing the furnace to conditions effective to produce a first liquid steel; d) providing a feed of iron containing by-products of an iron ore production process; e) injecting the feed of iron containing by-products into the first liquid steel at a flow rate in the range from about 20 to about 500 kg/min to form a blend; and f) subjecting the blend formed in step e) to conditions effective to produce a second liquid steel.

2 . The method of claim 1 , wherein the feed of the metallic scrap comprising steelmaking raw materials further comprises a direct reduced iron (DRI) comprising sponges, pellets, lumps, briquettes, or any combination thereof.

3 . The method of claim 1 , wherein the feed of iron containing by-products of an iron ore production process is provided by a conveyor belt.

4 . The method of claim 1 , wherein the iron containing by-products of an iron ore production process comprise direct reduced iron (DRI) fines.

5 . The method of claim 4 , wherein the direct reduced iron (DRI) fines comprise fines with an average size equal or smaller than about 6 mm.

6 . The method of claim 1 , wherein step e) occurs at a flow rate in the range from about 20 to about 300 kg/min.

7 . The method of claim 1 , wherein step e) occurs at a flow rate in the range from about 20 to about 100 kg/min.

8 . The method of claim 4 , wherein the produced second liquid steel exhibits lower nitrogen content than one measured for a substantially identical reference composition produced in the absence of the DRI fines.

9 . The method of claim 4 , wherein the DRI fines have a moisture content of less than about 0.3%.

10 . The method of claim 4 , wherein the DRI fines further comprise:
a) carbon in an amount in the range from greater than 0 to about 5 wt % based on the total weight of the DRI fines; b) a total iron content in an amount greater than about 90 wt % to less than about 100 wt % based on the total weight of the DRI fines; c) a metallic iron in an amount greater than about 80 wt % to less than about 100 wt % based on the total iron content in the DRI fines; and d) a gangue in an amount in the range from 0 wt % to about 10 wt % based on the total weight of the DRI fines.

11 . The method of claim 10 , wherein carbon is present in an amount greater than about 1.5 wt %.

12 . The method of claim 1 , wherein the injecting step e) utilizes at least one pneumatic lance.

13 . The method of claim 12 , wherein the pneumatic lance is positioned in the first liquid steel.

14 . The method of claim 13 , wherein the pneumatic lance is positioned in the first liquid steel at a depth in the range from about 600 mm to 1000 mm.

15 . The method of claim 12 , wherein the pneumatic lance is positioned at a 45° angle relative to the horizontal axis of the first liquid steel.

16 . The method of claim 4 , wherein the DRI fines are further introduced in combination with a carbon feed using a carbon pneumatic lance that is positioned in the first liquid steel at a depth in the range from about 600 mm to about 1000 mm, wherein:
the pneumatic lance is positioned at a 45° angle relative to the horizontal axis of the first liquid steel or the DRI fines and the carbon feed are each injected at a flow rate from about 20 to about 500 kg/min.

17 . (canceled)

18 . (canceled)

19 . (canceled)

20 . The method of claim 1 , wherein the furnace is an electrical arc furnace.

21 . The method of claim 1 , wherein conditions effective to produce the second liquid steel comprise:
heating the blend formed in step e) at a temperature in the range of from 1,400° C. to 1,700° C.; or heating the blend formed in step e) under a general atmospheric air environment.

22 . (canceled)

23 . A method for producing steel, the method comprising:
a) providing a first liquid steel; b) providing a feed of iron containing by-products of an iron ore production process; c) injecting the feed of iron containing by-products into the first liquid steel at a flow rate in the range from about 20 to about 500 kg/min to form a blend; and d) subjecting the blend formed in step c) to conditions effective to produce a second liquid steel.

24 . A steel comprising:
a) carbon present in an amount in the range from about 400 ppm to about 1500 ppm; b) a total iron content present in an amount in the range from greater than about 95 wt % to less than about 100 wt %; c) an iron oxide present in an amount of less than about 600 ppm; and d) nitrogen present in amount of less than about 120 ppm.

Assignees

• Saudi Basic Ind Corp

Inventors

• Al-Zeghaibi Othman N

Classifications

• C21C5/527

  Charging of the electric furnace · CPC title

• C21C5/5217

  equipped with burners or devices for injecting gas, i.e. oxygen, or pulverulent materials into the furnace · CPC title

• F27B2014/002

  Smelting process, e.g. sequences to melt a specific material · CPC title

• C21B13/143 Primary

  Injection of partially reduced ore into a molten bath · CPC title

• F27B14/06

  heated electrically, e.g. induction crucible furnaces with or without any other source of heat (F27B14/04 takes precedence) · CPC title