Aging (weathering) inhibition method of iron ore pellets during stockpiling

Patent metadata

Field	Value
Publication number	US-9631253-B2
Application number	US-201414572698-A
Country	US
Kind code	B2
Filing date	Dec 16, 2014
Priority date	Sep 5, 2011
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

The present invention refers to an effective method for minimizing the problems of iron ore pellet degradation by weathering during their stockpiling, i.e., by providing an appropriate method for improving the state of the art with regard to iron ore pellet resistance related just to the hydration process of the slag phase. Thus, in order to minimize hydration in the slag phase, stabilizers are introduced into the mixture used to produce iron ore pellets prior to being heat-treated.

First claim

The invention claimed is:

1. A method for producing iron ore pellets resistant to degradation during a slag phase aging process, comprising:
mixing iron ore pulp with aging inhibitors and forming iron ore pellets; and
heat-treating the iron ore pellets;
wherein the heat-treated iron ore pellets are resistant to degradation during the slag phase aging process;
wherein the mixing comprises adding the aging inhibitors to the iron ore pulp during the slag phase aging process as a particulate material <45 μm; and
wherein the heat-treated iron ore pellets meet the following conditions:
(CaO+Na 2 O+K 2 O)<45% and

(

SiO
2

⁢

/

⁢
60

)

+

(

AlO
⁢

⁢
3
⁢

/

⁢
102

)

(

CaO
⁢

/

⁢
56

)

+

(

Na
⁢

⁢
2
⁢

⁢
O
⁢

/

⁢
62

)

+

(

K
⁢

⁢
2
⁢

⁢
O
⁢

/

⁢
94

)

>

0.6
.

2. The method of claim 1 , wherein mixing and forming further comprises:
performing a cold agglomeration process to pelletize the mixed iron ore pulp and aging inhibitors or to form microagglomerates of the mixed iron ore pulp and aging inhibitors.

3. The method of claim 1 , wherein the aging inhibitors include metal oxides.

4. The method of claim 3 , wherein the metal oxides are selected from the group consisting of aluminum, kaolinite (Al 2 O 3 , 2SiO 2 , 2SH 2 O), fine silica, titanium oxides, Mg, and Zn.

5. The method of claim 3 wherein the metal oxides reduce K, Na, and Ca content of silicates.

6. The method of claim 3 , comprising:
adding the metal oxides to the iron ore pulp and testing at an increasing rate until a maximum limit has been reached, depending on a desired chemical stability of the heat-treated iron ore pellets.

7. The method of claim 1 , wherein the heat-treated iron ore pellets have a commercial grade chemical quality.

8. The method of claim 1 , wherein the heat-treated iron ore pellets are resistant to degradation depending on a type of calcium silicate and iron in the heat-treated iron ore pellets during the slag phase aging process.

9. The method of claim 1 , wherein 80% of the particulate material is <20 μm.

10. A method for producing iron ore pellets resistant to degradation during a slag phase aging process, comprising:
mixing iron ore pulp with aging inhibitors and forming iron ore pellets; and
heat-treating the iron ore pellets;
wherein the heat-treated iron ore pellets are resistant to degradation during the slag phase aging process;
wherein the mixing comprises adding the aging inhibitors to the iron ore pulp as a particulate material <45 μm; and
wherein the heat-treated iron ore pellets meet the following conditions:
(CaO+Na 2 O+K 2 O)<45% and

(

SiO
2

⁢

/

⁢
60

)

+

(

Al2O3
⁢

/

⁢
102

)

(

CaO
⁢

/

⁢
56

)

+

(

Na2O
⁢

/

⁢
62

)

+

(

K2O
⁢

/

⁢
94

)

>

0.6
.

Assignees

• Vale Sa

Inventors

• Vieira Maria Beatriz Harmendani
• Botelho Marcus Eduardo Emrich

Classifications

• C22B1/2413

  enduration of pellets · CPC title

• C22B1/16

  Sintering; Agglomerating · CPC title

• C22B1/2406 Primary

  pelletizing · CPC title