FIELD OF THE INVENTION
The present invention relates to a system for easy lifting of worn-out
troughs of blast furnace and/or replaceable constructional items such as
those made of refractory castables/cement concretes.
BACKGROUND AND PRIOR ART
Main troughs of Blast furnaces are used for pooling of hot metal for taking
the impact of the hot metal from the taphole which subsequently falls in
to ladles through runners. In addition to this the main troughs are also
used for seperation of slag which goes to slag pots or slag granulation
units. The working lining of troughs is generally made of
ramming mass in order to have improved trough life. At the end of the
campaign life with the rammed trough mass, it is completely dug up to
the safety lining for installation of the new trough mass for next
campaign.
The trough mass gets hard while in service and it is very
difficult to dig the same with manual labour since no other means is
available for doing the same. Pneumatic chiseles/concrete breakers are
employed for digging/cleaning of the worn-out trough mass and this job is
done in a hot and arduous conditions. The process of digging and
cleaning consumes a lot of time, from 10-15 hrs in bigger furnaces (>1500
Tons/day production) to 8-10 hours in smaller ones which adversely
affects the productivity of the units. This leads to longer shut down of cast
house for relining of trough and thereby reduction in cast house
availability and hot metal productivity.
OBJECTSOF INVENTION
It is thus the basic object of the present invention to provide for a system
which would assist the process of digging and cleaning of worn out trough
mass of blast furnaces such that the same can be carried out faster,
efficiently and in pleasant environment/condition.
Another object of the present invention is to provide for an efficient
system for lifting of blast furnace trough whereby the digging/cleaning of
worn out trough mass of blast furnace can be carried out more efficiently
and fast without much adversely affecting the productivity of the blast
furnace.
Yet further object of the present invention is to make the process of
digging/cleaning of blast furnace trough mass more economical and user
friendly by facilitating, convenient, digging/ cleaning of worn out troughs
of blast furnaces.
SUMMARY OF THE INVENTION
Thus according to the present invention there is provided a apparatus for
easy lifting of worn out troughs of blast furnace comprising :
a lifting cage having a horizontally positioned bottom and at least two
side walls secured to said bottom, said dimensions of said bottom and
side walls being determined based upon the blast furnace trough to be
lifted ;
means adapted to securedly hold said lifting cage by means of a lifting
mechanism.
A
DESCRIPTION OF THE INVENTION
Importantly, the construction of the cage involves provision of stiffners
between side member and bottom member and also provisions of hooks to
fasten steel rope and the like for pulling/lifting of the trough.
It is thus possible by way of the above disclosed system of the invention to
lift the worn out trough from arduous furnace condition to more
comfortable environment for facilitating fast and effective digging/cleaning
of the trough mass. The system effectively reduces the cleaning/digging
time by provision of the trough lifting cage which is found to save time for
digging/cleaning of the trough.
The size of the cage depends upon the shape and sizes of the trough shell
plate and the safety lining over the shell plate. The dimensions, therefore,
can vary and also depend on the capacity of the lifting mechanism such
as cranes and the like.
The lifting cage of the system of the invention is thus required to be
constructed based upon the shape and dimension of the blast furnace
trough. The trough is usually constructed of metallic shell, safety brick
lining on the metallic shell and over that trough mass is rammed.
The side walls and bottom of the lifting cage is made of segments of 500-
1000 mm length and height of side walls is maintained at about half of
that of the trough wall. Two pieces of side walls are welded to the bottom
piece at the same angle as that of the angle of the BF trough side walls.
This constitutes one segment. Depending on the length of the main
trough of BF and the capacity of the lifting device like overhead crane
available in the BF cast house, the length of the cages are selected
between 500-1000 mm.
The details of the invention, its objects and advantages are discussed in
greater details with reference to non-limiting exemplary embodiment of
the apparatus of the invention in relation to the accompanying figures
wherein
Fig. 1 is side view of the system of the invention.
Fig. 2 is the other side view of the system of the invention.
Fig. 3 is an elevational view of the system, while
Fig. 4 is a top plan view of the apparatus of the invention.
As illustrated in the said Figs. 1-4, the system essentially comprises of
the cage for lifting of the trough of blast furnace having basically a bottom
(BO) and side walls (SI).
As further illustrated in the said figures the length (a) of the cage can vary from 500 - 1000
mm. The width (B) in the bigger end of the cage at the bottom is variable, the width (C) in
the smaller end of the cage at the bottom is also variable. The width (D) at the top of the
cage at the bigger end is also variable while the width (E) at the top of the cage in smaller
end, is also variable.
It would thus be evident from the above that the construction of the cage in particular, its
shape and dimension are obviously governed by the specifications of the blast furnace
trough to be lifted.
In particular a preferred embodiment of the manufacture of the cage is discussed
hereunder:
3 mild steel plates of max. 1000mm length, 50 mm width and 10 mm thick are placed in an
angle equivalent to the angle of the trough and 5 short plates of length approximately
equivalent to that of the width of the trough are placed over the long plates and jointed
them by welding at middle and both end. This forms the bottom portion of the cage.
Five short plates of the bottom are then joined by welding 5 plates of length about half of
that of height of the trough bank at angle equivalent to that of the trough bank. These 5
plates are welded to other 3 plates whose length is equivalent to that of the length of the
bottom long plates each at bottom, middle and top. This forms the one side wall of the
lifting cage. In the same way, the other side wall is also fabricated. Stiffeners have been
provided at the joining positions of bottom and side walls. A lifting arrangement is made at
the top in all the four corners for easy lifting of the cage with the overhead crane.
The reason for keeping the height of the cage approx. half of that of the trough bank is to
avoid any leakage of the hot metal through the embedded metal parts of the cage.
c) Depending on the length of the trough and capacity of the overhead crane provided in the
shop, number of cage segments are designed and fabricated whose length may vary from
500 to 1000 mm and placement of them is made as per their designated position.
As would be evident from the above, the system for lifting of worn out trough of blast furnace is
simple and cost effective.
The apparatus is directed to effectively carry out digging/cleaning of trough in 4-5 hours duration
instead of the usual 8-10 hours in case of small blast furnaces thereby resulting in considerable
saving in time. Moreover, the time saved can be utilized for taking additional costs and make
the process of casting more economical and cost effective.
The apparatus of the invention provides for easy lifting of worn-out troughs of blast furnace and
thereby reducing the total trough preparation time i.e. jam removal, new trough making etc., by
about 40-50% and thereby avoiding missing of cast.
WE CLAIM :
0
1) A apparatus for easy lifting of worn out troughs of blast furnace
comprising :
a lifting cage having a horizontally positioned bottom and at least two
side walls secured to said bottom, said dimensions of said bottom and
side walls being determined based upon the blast furnace trough to be
lifted ;
means adapted to securedly hold said lifting cage by means of a lifting
mechanism.
2) A apparatus as claimed in claim 1 wherein the side walls and the bottom
of lifting cage constitute segment of 500 - 1000 mm length.
3) A apparatus as claimed in any one of claims 1 or 2 wherein the height of
the side walls is about half of that of the trough walls.
4) A apparatus as claimed in any one of claims 1-3 wherein two pieces of
the side walls are welded to the bottom at the same angle as that of the
angle of the blast furnace trough.
5) A apparatus as claimed in any one of claims 1-4 wherein the length of
the cage is in the range of 500 - 1000 mm.
6) A apparatus as claimed in any one of claims 1-5 wherein the said bottom
of said cage comprises plurality of plates welded perpendicular to sheet
plate of a length equal to that of the width of the trough in both ends
and middle portion of the long plate.
') A apparatus as claimed in claim 6 wherein said plurality of plates
comprise mild steel plates of upto 1000 mm length, 50 mm width and
10 mm thickness.
8) A apparatus as claimed in any one of claims 1-7 wherein the horizontally
welded plates at least at the sides of the bottom are welded to side
plates which are angularly disposed and extended to a height half that
of the blast furnace trough side height.
9) A apparatus as claimed in claim 8 wherein said side plates are also
welded to long plates along the length of the trough.
10) A apparatus as claimed in any one of claims 1-9 wherein each said
segment formed by said interconnected plates are varied and
dimensioned depending upon the length and dimensions of the trough.
11) A apparatus as claimed in any one of claims 1-10 wherein the shape
and size of the lifting cage is determined based upon the shape and
size of the blast furnace trough to be lifted.
12) A apparatus as claimed in any one of claims 1 to 11 wherein said
means for securedly holding the lifting cage by a lifting mechanism
comprises hooks welded to said lifting cage.
13) A apparatus as claimed in any one of claims 1 to 12 comprising
stiffners provided there between the side members and bottom
members of the lifting cage.
14) Use of the apparatus as claimed in any one of claims 1 - 13 for lifting
of worn out troughs of blast furnace and/or replaceable constructional
items made out of refractory castables/cement concrete.
15) An apparatus for easy lifting of worn out troughs of blast furnace and/or
replaceable construction items made of refractory castables/cement
concrete substantially as herein described and illustrated with
reference to the accompanying figures.

An apparatus for easy lifting of worn-out troughs of blast furnace and/or
replaceable constructional items such as those made of refractory
castables/cement concretes. The system utilizes a lifting cage for lifting
of the worn-out trough to thereby facilitate the process of digging and
cleaning of worn-out troughs of blast furnaces faster, efficiently and in
pleasant environment/conditions. The system is user friendly and
economical for use in lifting of worn-out troughs of blast furnaces.