P process of making pig iron in a blast furnace using pellets containing thermoplastic and cellulosic materials
The use of pellets comprising one or more thermoplastic material(s) of more than 40%, based on the total dry weight of the pellets and one or more cellulosic material(s) of more than 20%, based on the total dry weight of the pellets, as a reducing agent in a process for making pig iron in a blast furnace. The pellets can be provided in unground form, as a partial replacement of coke through the top of the blast furnace, or can be provided as reducing agent in the raceway in an amount of higher than 10 kg/ton iron.
1. Process of making pig iron in a blast furnace having a raceway, said process comprising the steps of:
a) charging the blast furnace with a top feed comprising an iron ore and coke;
b) injecting a reducing agent into the blast furnace at the level of one or more tuyeres in the raceway of the blast furnace;
c) feeding hot air in the raceway of the blast furnace, wherein the blast furnace is furthermore charged with pellets in unground form as a reducing and energy supply agent in an amount of higher than 10 kg/ton iron, said pellets comprising:
one or more thermoplastic material(s) of more than 40 weight %, based on the total dry weight of the pellets; and
one or more cellulosic material(s) of more than 20 weight %, based on the total dry weight of the pellets
d) and obtaining pig iron at the bottom of the blast furnace.
2. Process according to claim 1 , wherein the pellets are provided in the top feed together with the iron ore and coke as partial replacement of coke.
3. Process according to claim 1 , wherein said reducing agent in step (b) comprises said pellets.
4. The process according to claim 3 , wherein the pellets are having a heating value for incomplete combustion (HVIC) calculated with the formula:
C
c
H
h
O
o
N
n
+
c
-
o
2
·
O
2
=
c
·
CO
+
h
2
·
H
2
+
n
2
·
N
2
in the range of about 6 to about 7 MJ/kg;
and wherein the pellets are having a calorific value (LCV) of 22-28 GJ/ton.
5. The process according to claim 1 , wherein the pellets are having a heating value for incomplete combustion (HVIC) calculated with the formula:
C
c
H
h
O
o
N
n
+
c
-
o
2
·
O
2
=
c
·
CO
+
h
2
·
H
2
+
n
2
·
N
2
in the range of about 6 to about 7 MJ/kg.
6. The process according to claim 1 wherein the oxygen content of the pellets is in the range of 20 to 30 wt % of the dry weight pellets.
7. The process according to claim 1 , wherein the hydrogen content of the pellets is in the range of 7 to 8 wt % of the dry weight pellets.
8. The process according to claim 1 , wherein the pellets have a calorific value (LCV) of 22-28 GJ/ton.
9. The process according to claim 1 , wherein an amount of pellets is used of more than 12 kg/ton metal.
10. The process according to claim 9 , wherein an amount of pellets used is about 50-200 kg pellets per ton of hot metal.
11. The process according to claim 1 , wherein the pellets comprise:
one or more thermoplastic material(s) in an amount of 40-70 weight %, based on the total dry weight of the pellets; and
one or more cellulosic material(s) in an amount of 30-50 weight % based on the total dry weight of the pellets.
12. The process according to claim 1 , wherein the pellets have a diameter of between 6 and 20 mm and a length of between 4 and 50 mm.
13. The process according to claim 1 wherein the raceway is held at an adiabatic flame temperature in the range of about 1900° C. to about 2500° C. and air volume in the range of 1280-2000 Nm 3 /kg*1000.
14. Process of making pig iron in a blast furnace, said said process comprising the steps of:
a) charging the blast furnace with an iron ore and coke;
b) injecting a reducing agent into the blast furnace at the level of one or more tuyeres in the raceway of the blast furnace;
c) feeding hot air in the raceway of the blast furnace, wherein the blast furnace is furthermore charged with pellets in unground form as a reducing and energy supply agent in an amount of higher than 10 kg/ton iron, said pellets comprising:
one or more thermoplastic material(s) of more than 40 weight %, based on the total dry weight of the pellets; and
one or more cellulosic material(s) of more than 20 weight %, based on the total dry weight of the pellets;
d) and obtaining pig iron at the bottom of the blast furnace;
wherein said reducing agent in step (b) comprises said pellets;
wherein the oxygen content of the pellets is in the range of 20 to 30 wt % of the dry weight pellets;
wherein the hydrogen content of the pellets is in the range of 7 to 8 wt % of the dry weight pellets;
wherein the pellets have a diameter of between 6 and 20 mm and a length of between 4 and 50 mm.
15. The process according to claim 14 , wherein the pellets are having a heating value for incomplete combustion (HVIC) calculated with the formula:
C
c
H
h
O
o
N
n
+
c
-
o
2
·
O
2
=
c
·
CO
+
h
2
·
H
2
+
n
2
·
N
2
in the range of about 6 to 7 MJ/kg.
16. The process according to claim 15 , wherein the pellets are having a calorific value (LCV) of 22-28 GJ/ton.