Specialized metallurgical processes – compositions for use therei – Compositions – Solid treating composition for liquid metal or charge
Reexamination Certificate
2000-08-31
2001-08-28
Andrews, Melvyn (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Compositions
Solid treating composition for liquid metal or charge
C075S313000, C075S459000, C075S460000, C075S471000
Reexamination Certificate
active
06280498
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a synthetic resin fuel to be blown in through tuyeres for pig iron production in blast furnaces. The present invention relates also to a process for pig iron production with said synthetic resin fuel.
2. Description of the Related Art:
Blast furnaces need comparatively expensive coke for pig iron production. One way adopted to reduce coke consumption is to blow into tuyeres a variety of fuels such as natural gas, naphtha, heavy oil, tar, and pulverized coal.
There has recently been proposed a new technology of utilizing waste plastics material from the standpoint of waste disposal and recycling. For example, Japanese Patent Laid-open No. 143526/1997 discloses the use of a synthetic resin material having a specific surface area greater than 50 m
2
/kg for efficient combustion in blast furnaces.
For effective use of waste plastics material as a fuel, investigations are continuing an its shape and other factors that affect combustion efficiency and stable furnace operation.
Important factors for stable furnace operation include (1) the constant size of the raceway combustion zone, (2) the stable gas flow from the combustion zone, and (3) ability to be transferred over a long distance to tuyeres without clogging. Waste plastic material as a fuel is usually used in the form of agglomerated pellets having a large specific surface area for efficient combustion. In their half-molten state, such plastic pellets easily break during transfer or pressure-feeding to tuyeres. Broken pellets cause bridging in hoppers and clogging in pipes. In other words, they present difficulties in their long-distance transfer.
OBJECT AND SUMMARY OF THE INVENTION
The present invention was completed in view of the foregoing. It is an object of the present invention to provide a synthetic resin fuel for pig iron production by stable blast furnace operation. It is another object of the present invention to provide a process for producing pig iron with said synthetic resin fuel.
The first aspect of the present invention resides in a synthetic resin fuel for pig iron production in a blast furnace, said synthetic resin fuel being in the form of cylindrical pellets, each measuring X mm in thickness and Y mm in diameter, with X and Y satisfying the following three expressions.
3.0≦X≦10
2≦Y≦20
Y/X≧1.5
The cylindrical pellets defined above are produced by melting a resin, solidifying the melt, and cutting the solidified product. The raw material of the resin may be crushed waste plastic material. The cylindrical pellets should preferably contain more than 0.05wt % of water.
The second aspect of the present invention resides in a process for producing pig iron in a blast furnace by blowing a synthetic resin fuel into a blast furnace through tuyeres, wherein said synthetic resin fuel is in the form of cylindrical pellets, each measuring X mm in thickness and Y mm in diameter, with X and Y satisfying the following three expressions.
3.0≦X≦10
2≦Y≦20
Y/X≧1.5
The cylindrical pellets defined above are produced by melting a resin, solidifying the melt, and cutting the solidified product. The raw material of the resin may be crushed waste plastic material. The cylindrical pellets should preferably have a size distribution such that those having a diameter within ±20% of the average diameter account for more than 70 wt %. The cylindrical pellets should preferably contain more than 0.05 wt % of water.
REFERENCES:
patent: 5772727 (1998-06-01), De Haas et al.
patent: 5992335 (1999-11-01), Nakamura et al.
patent: 9-143526 (1997-06-01), None
patent: 10-305430 (1998-11-01), None
patent: 11-080763 (1999-03-01), None
Nozawa Kentaro
Yoshida Yasuo
(Kobe Steel, Ltd.)
Andrews Melvyn
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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