Ducting for manufacture of iron

Patent metadata

Field	Value
Publication number	US-2016258687-A1
Application number	US-201615042550-A
Country	US
Kind code	A1
Filing date	Feb 12, 2016
Priority date	Mar 4, 2015
Publication date	Sep 8, 2016
Grant date	—

Abstract

In the reduction of iron oxides to iron at temperatures greater than about 700° C. the propensity for the formation of coke in the duct work between furnaces is reduced by using steel having a surface comprising a spinel of the formula Mn x Cr 3-x O 4 wherein x is from 0.5 to 2.

First claim

What is claimed is:

1 . In an apparatus for the production of pig iron in which hot reducing gas from the top of a blast furnace or a fluidized bed iron ore reduction reactor is cleaned of residual particulate matter and transferred through a transfer line to and upstream fluidized bed iron ore reduction reactor or pre-heater the improvement comprising forming the transfer line from a metal selected from the group consisting of carbon steel, stainless steel, heat resistant steel, HP, HT, HU, HW and HX stainless steel, and nickel or cobalt based HTA alloys having on its internal surface a coating having a thickness from 10 to 5,000 microns comprising from 40 to 60 weight % of compounds of the formula Mn x Cr 3-x O 4 wherein x is from 0.5 to 2 and from 60 to 40 weight % of oxides of Mn and Si selected from of MnO, MnSiO 3 , Mn 2 SiO 4 and mixtures thereof provided that the surface contains less than 5 weight % of Cr 2 O 3 .

2 . The apparatus according to claim 1 , wherein the hot reducing gas from the top of a blast furnace or a fluidized bed iron ore reduction reactor is cleaned of residual particulate matter using one or more separators selected from of a cyclone and a magnetic filter.

3 . The apparatus according to claim 2 , wherein not less than 85% of the inner surface of the transfer line is covered with said coating.

4 . The apparatus according to claim 3 , wherein said coating has a thickness from 10 to 1,000 microns.

5 . The apparatus according to claim 4 , wherein in said coating Cr 2 O 3 is present in an amount of less than 2 weight %.

6 . The apparatus according to claim 4 , wherein the transfer line comprises from 13 to 50 weight % of Cr and from 20 to 50 weight % of Ni.

7 . The apparatus according to claim 4 , wherein the transfer line comprises from 50 to 70 weight % of Ni; from 20 to 10 weight % of Cr; from 20 to 10 weight % of Co; and from 5 to 9 weight % of Fe.

8 . The apparatus according to claim 4 , wherein the transfer line comprises from 40 to 65 weight % of Co; from 15 to 20 weight % of Cr; and from 20 to 13 weight % of Ni; less than 4 weight % of Fe; and up to 20 weight % of W.

9 . The apparatus according to claim 6 , wherein the oxide is MnO.

10 . The apparatus according to claim 6 , wherein the oxide is MnSiO 3 .

11 . The apparatus according to claim 6 , wherein the oxide is Mn 2 SiO 4 .

12 . The apparatus according to claim 6 , wherein the oxide is a mixture of MnO, MnSiO 3 and Mn 2 SiO 4 .

13 . The apparatus according to claim 7 , wherein the oxide is MnO.

14 . The apparatus according to claim 7 , wherein the oxide is MnSiO 3 .

15 . The apparatus according to claim 7 , wherein the oxide is Mn 2 SiO 4 .

16 . The apparatus according to claim 7 , wherein the oxide is selected from MnO, MnSiO 3 , Mn 2 SiO 4 and mixtures thereof.

17 . The apparatus according to claim 8 , wherein the oxide is MnO.

18 . The apparatus according to claim 8 , wherein the oxide is MnSiO 3 .

19 . The apparatus according to claim 8 , wherein the oxide is Mn 2 SiO 4 .

20 . The apparatus according to claim 8 , wherein the oxide is a mixture of MnO, MnSiO 3 and Mn 2 SiO 4 .

21 . In a process to reduce fine iron ores to sponge iron at a temperature from 700° C. to 900° C. and a pressure from 2 to 5 barg in the presence of a reducing gas in a series of two or more fluidized bed reactors wherein a reducing gas is passed from an upstream fluidized bed reactor to a downstream fluidized bed the improvement comprising removing particulate iron ore from the reducing gas prior to transfer to an upstream fluidized bed reactor and constructing the conduit for transferring said reducing gas relatively free of particulate iron ore of a metal selected from carbon steel, stainless steel, heat resistant steel, HP, HT, HU, HW and HX stainless steel, and nickel or cobalt based HTA alloys said conduit having on its internal surface a coating having a thickness from 10 to 5,000 microns comprising from 40 to 60 weight % of compounds of the formula Mn x Cr 3-x O 4 wherein x is from 0.5 to 2 and from 60 to 40 weight % of oxides of Mn and Si selected from of MnO, MnSiO 3 , Mn 2 SiO 4 and mixtures thereof provided that the surface contains less than 5 weight % of Cr 2 O 3 .

22 . The process according to claim 21 , the reducing gas comprises from 50 to 70 mole % of CO, from 30 to 15 mole % of H 2 , from 10 to 5 mole % of CO 2 , and from 0 to 10 mole % of N 2 the sum of said components adding up to 100 mole %.

23 . The process according to claim 22 , wherein the fine iron particles comprise at least 50 wt. % of one or more members selected from Fe, FeO, Fe 2 0 3 , and Fe 3 0 4 .

Assignees

• Nova Chemicals International Sa

Inventors

• Simanzhenkov Vasily
• Berghmans Michel
• Farag Hany Iskandar

Classifications

• C21B2100/44

  Removing particles, e.g. by scrubbing, dedusting · CPC title

• C04B2235/3262

  Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO · CPC title

• C04B2235/3427

  Silicates other than clay, e.g. water glass · CPC title

• C04B35/16

  based on silicates other than clay {(zircon C04B35/48)} · CPC title

• C21B2100/60

  Process control or energy utilisation in the manufacture of iron or steel · CPC title