The present invention relates to an apparatus for evaluation of flow
characteristics and setting behaviour of blast furnace taphole mass under
simulated conditions.
In steel plants taphole mass is used for plugging in tapholes of blast furnace at
the end of each tapping of hot metal. The pasty mass, called as 'tap hole mass',
is a mixture of refractory grains and liquid resin/tar as binder. This pasty mass is
pushed into the taphole by an extruder known as 'mudgum machine', which is
hydraulically or electromechanically operated.
The performance of the mass during tapping of hot metal, depends on how well
the extruded mass flowed inside the hot taphole during plugging and
subsequently got set therein. Sometimes, insufficient flowability of the mass at
higher temperature results in short taphole and thereby causes fast flow during
tapping. This intern forces to reduce the blast pressure resulting loss in
production. If the mass is not set properly, there is a strong possibility of self
opening of the taphole. Besides, the premature setting of the mass within the
mudgun, sometimes, poses lot of troubles in mudgun operation.
The productivity of BF is affected due to inconsistent behaviour of the taphole
plugging mass. Sometimes the mudgun mass contains thermo-setting resin in the
form of powder or liquid, on heating this mass starts curing/setting and so its flow
characteristics changes. Sometimes the mass is cured prematurely inside the
taphole resulting short taphole and thereby causes fast flow during casting. This
inturn forces to reduce the blast pressure resulting losses in production. If the
mass is not cured properly, there is a strong possibility of self opening of taphole.
The known ASTM methods for testing the workability as well as other properties
e.g. strength, porosity and volatile matter etc. for this type of materials indicate
the properties at room temp, which are difficult to correlate with the actual
performance.
Thus the problems encountered with taphole mass are mainly :
i) Inconsistent behaviour of taphole mass greatly affects the productivity of
blastfurnace.
ii) Facilities such as type of mudgun and drilling machine varies from plant to
plant and even from furnace to furnace which requires different quality of
taphole mass for different furnaces.
• iii) Till date, no standard test method is available for testing of flow
characteristics and setting behaviour of such type of material. The
conventional methods of testing workability, strength etc. seldom
correlates the actual performance of taphole mass in the furnace.
It is thus the basic object of the present invention to provide an apparatus for
evaluation of flow characteristics and setting behaviour of blast furnace taphole
mass under simulated working conditions which would assist in predicting its
actual performance in a particular blast furnace.
Another object of the present invention is to provide an apparatus for evaluation
of flow characteristics and setting behaviour of blast furnace taphole mass under
simulated working condition which would avoid the problems of inconsistent
behaviour of taphole mass and consequent loss in productivity of blast furnaces.
Yet another object of the present invention is to provide an apparatus for
evaluation of flow characteristics and setting behaviours of blast furnace taphole
mass under simulated working conditions which would assist in evaluating the
proper taphole mass depending upon the furnace characteristics and working
appratus/conditions.
Yet further object of the present invention is to provide an apparatus for
evaluation of flow characteristics and setting behaviour of blast furnace taphole
mass under simulated working conditions which would effectively correlate the
actual performance of taphole mass in the furnace.
Thus according to the present invention there is provided an apparatus for
evaluation of flow characteristics and setting behaviour of blast furnace taphole
mass under simulated working conditions comprising :
a mudgun having means to heat the taphole mass ;
a chamber furnace housing a means simulating to the taphole of a blast furnace ;
and
means for pushing ;
said taphole mass from said mudgun into the said means simulating to the
taphole.
Preferably, the said means for simulating to the taphole is a heat resistant sleeve
housed within said chamber furnace. One end of the sleeve is maintained
adjacent the mudgun exit while the other end is used to monitor the condition of
the taphole mass.
In the above disclosed apparatus of the invention the mudgun used is totally
different than the mudgun machine used in the plant. This is developed
specifically to suit the above apparatus of the invention.
In particular, the mudgun used in the apparatus of the invention is cylindrical
shaped with a nose like front end positioned adjacent said furnace chamber. The
mudgun is operated hydraulically with electrical heating means preferably
detachable provided in the nose area. Thermocouple is provided to measure
shell temperature. The mudgun is mounted on a trolley and can be positioned
anywhere along the length. Operating pressure of the mudguns range from 10 -
50 Kg/cm2. Temperature regulation at the surface of the mudgun is done at about
(50 - 350°C) with a suitable controller.
The chamber furnace used on the apparatus is basically electrically operated
preferably at operating temperature 1100°C (max.) for 1 hr., 1000°C for
continuous run. Heating element in the furnace comprise Nichrome wire coil.
Insulation is provided with suitable high alumina refractory to withstand
temperature of about 1100°C. A temperature controller is used which can be a
digital on-off controller to control accuracy ±3°C of set point.
The chamber housing the heat resistant sleeve which is preferably detachable
stainless steel sleeve (size : 350 mmx x 50 mm inner dia.) through which the mud
will be extruded. This resembles the actual blast furnace taphole of length (2-3
m). The sleeve is made of special stainless steel suitable to withstand 1100°C
without any deformation on repeated use. To facilitate cleaning, sleeve is split
into two parts along the length. After the experiment, the sleeve is taken out from
the furnace and cleaned.
The exhaust is provided to give a passage for evolved gases from the mass to
come out of the furnace. A plugging means, preferably ceramic plug is used
mainly to close the hole of the SS tube to prevent air infiltration inside the furnace
and to avoid burning of gases generated from tar used as binder of the mass.
The pushing of mudgun mass from the mudgun is achieved by suitable hydraulic
apparatus operating at a pressure of 10 - 50 kg/cm2 with pressure gauge having
least count of 1 - 2 kg/cm2. For controlling of pressure to any desired level
suitable control valve is provided.
Apart from observing the flow characteristics and setting behaviour of the
extruded mass physically, the apparatus can measure the quantity of material
extruded at a particular set value of operating pressure of mudgun.
Similarly, the effect of temperature on flow characteristics of the mass can also
be observed by pushing the mudgun piston at a particular pressure and at a
particular desired set value of temperature. This is done by sensing the
temperature at the surface of the mudgun by thermocouple and control it by the
controller installed in the mudgun panel.
The quality of the mudgun mass to be used in BF can be assessed in a more
reliable way before it's application and the consistency with respect to
extrudability, strength, setting characteristics etc. can be maintained. This will
reduce the chances of failure of the mass during it's application. Thus the
possibility of intermittent blast reduction is reduced inturn improves the
productivity of BF.
The details of the invention, its objects and advantages are explained hereunder
in greater detail in relation non-limiting exemplary embodiments of the apparatus
as per the accompanying figures wherein ;
Fig. 1 is a schematic illustration of the apparatus of the invention.
Fig. 2 illustrates the stainless steel tube housed within the chamber furnace.
Fig. 3 is a sectional view of the mudgun used in the apparatus of the invention.
Fig. 4 illustrates the hydraulic means operative apparatus connected to the
mudgun.
Reference is first invited to Fig.1 which schematically illustrates the apparatus of
the invention comprising the mudgun (MG) with operative hydraulic means (HM)
mounted on a trolley (TR). The mudgun having a nose like (NS) point which is
maintained in alignment with the stainless steel tube (SST) housed within the
furnace chamber (FC). The stainless steel tube which is heat resistant simulates
the taphole of a blast furnace. While the taphole mass is extruded from said
mudgus and pushed into the adjacent end (AE) of the tube (SST) in the furnace
chamber (FC) at different temperature of upto 1100°C, its setting behavour can
be monitored from the other end (OE) of the tube. When not in use for such
observation, the other end (OE) of the tube away from the mudgun is plugged by
a ceramic plug (CP). Clamp means (CM) are provided to releasibly house the
tube (SST) within the chamber furnace (CF). An exhaust means (EM) is provided
to favour exhaust gases to exit and of the furnace. The furnace size is preferably
200 x 200 x 200 mm and is electrically operated to be heated to operating
temperatures of 1100°C for an hour and upto 1000°C for continuous run. Heating
is achieved by nichrome wire coil. The inside of the furnace is lined by refractory
material such as high alumina refractory to withstand the above operating
temperatures. Suitable temperature controllers are also provided in the furnace.
Reference is now invited to Fig. 2 which shows the stainless steel tube housed
within the chamber furnace. The detachable tube (SST) is preferably of 350mm x
50mm inner dia. through which the mud is extruded. The same resembles the
actual blast furnace taphole of length 2 - 3 mm. The sleeve is made of stainless
steel suitable to withstand 1100°C without any deformation on repeated use. To
facilitate the cleaning the sleeve is split into two parts along the length. After the
test is over, the sleeve can be taken out of the furnace and cleaned.
Reference is now invited to Fig. 3 which illustrated the hydraulic mudgun
equipment used in the apparatus.
Mudgun is preferably in two parts (one fixed and other detachable) and made of
stainlesss steel of quality SS 304. Detachable heating arrangements with
approximately 1 kW power is provided in detachable portion of the mudgun as
shown in the figure.
As also illustrated in the figure heating arrangement and its control apparatus are
installed in the nose portion of the mudgun. In this detachable portion, over the
metallic shell insulating material is cast alongwith heating coil. The casting is
dried at 110 - 120°C and fired at 1200°C. the power supply in the heating coil is
220V Ac, 50Hz, single phase.
In order to control the temperature in between (50 - 350°C) at the surface of the
mudgun, one Fe/Pt thermo-couple is inserted through the shell by drilling. A
suitable digital temperature controller on-off type is provided in the control panel.
Reference is now invited in Fig. 4 which illustrates the hydraulic operation of the
mudgun (MG) for pushing mudgun mass from the mudgun, a suitable hydraulic
apparatus as illustrated is used. The hydraulic apparatus consists of the following
features ::
- Oil tank of size 500 x 300 mm
- Quality of hydraulic oil used : Grade 40
- Type of Pump (P): Single acting rotary pump.
- Motor (M): 1 H.P, 220V, AC, 50Hz, Single phase.
- Pressure control valve (V).
Flow control valve
- Hydraulic cylinder (HC) made of S.S 304 quality steel
- Pressure gauge (PG) (0 - 250 kg/cm2) of least count (1-2 kg/cm2)
The hydraulic apparatus is developed based on the requirement and this is one
of the major innovative parts of the developed item.
In order to asses the quality of the mass in the laboratory before application in
plant, the developed prototype mudgun machine was used and the actual
operating conditions of a particular blast furnace have been simulated. The
variation of temperature of the mudgun mass inside the mudgun at different
stages of casting in the cast house was measured. The maximum temperature
recorded was around 300°C.
Different experimental batches by varying the quantity of binder, plasticizer and
pitch powder were made in a laboratory mixer. The masses were then tested in
the developed equipment by maintaining the maximum temperature of 300°C in
the nose portion of the mudgun. The extrudability, strength and setting time were
measured as given in Table 1.
The binder used in the above formulations was of thermo-setting type and its
setting/curing time was optimised by addition of plasticizer. One of the objectives
of using this type of binder was to withdraw the mudgun as early as possible after
the pushing of the mass inside the blast furnace taphole is over. Hence, it was
decided to use the formulation having workability/extrudability in the range 3.0 to
3.5 mm/sec, strength 60-75 kg/cm2 and setting time 90-120 sec.
In the plant 1T mass/batch was prepared in a rotoary planetory type mixer where
intensive mixing of the ingredients were ensured. The properties of the mass was
tested and the results are given in Table 2.
Table - 2
The trial batch No. 8 having extrudability 3.0 mm/sec, setting time 60 sees.
Crushing strength of 90 kg/cm2 and coked porosity of 30% was chosen for plant
i) Holding time of the mudgun reduced from earlier period of 25 minutes to 1
minute,
ii) The workability of the materials was consistent throughout the trial period
and there was no problem of drilling and thereby no delay observed while
opening the taphole.
Thus both holding time of mudgun machine i.e. setting time of the mass and
workability as determined by the developed simulative mudgun machine are in
agreement with the performance in plant scale trials.
It is thus possible by way of the apparatus of the invention to have an apparatus
and method of testing flow characteristics of taphole mass at different
temperature and extrusion pressure which gives a clear idea about the behaviour
of the of the mass under actual working condition.
Also, by use of the apparatus the composition of the taphole mass can be tailored
according to the specific operational conditions and type of facilities of a
particular blast furnace.
Importantly, the problem in inconsistent behaviour of taphole mass which affect
the productivity of blast furnace can be eliminated by use of the above apparatus.
By the apparatus the reliability of the mass can more accurately be assessed
before its application and thereby the productivity of the furnace will be improved.
WK CLAIM :
1. An apparatus for evaluation of flow characteristics and setting behaviours of blast
furnace taphole mass under simulated working conditions comprising :
a mudgun (MG) having means to heat the taphole mass ;
a chamber furnace (FC) housing means simulating the taphole of a blast furnace ; and
means for pushing said taphole mass from said mudgun into said means simulating
the taphole.
2. An apparatus as claimed in claim 1 wherein said mass for simulating the taphole
comprise heat resistant sleeve housed within said chamber furnace, one end (AH) of
said sleeve maintained in alignment with and adjacent to the said mudgun exit while
the other end (OH) is adapted lor viewing of the taphole mass in said sleeve.
3. An apparatus as claimed in anyone of claims 1 or 2 wherein said mudgun is
cylindrical shape with a nose (NS) like extending exit end portion adjacent said
furnace chamber.
4. An apparatus as claimed in anyone of claims 1 to 3 wherein said mudgun is
hydrau 1 ica 11 y operated.
5. An apparatus as claimed in anyone of claims 1 to 4 wherein said mudgun comprise
detachable electrical heating means provided in said nose like extending portion of the
mudgun.
6. An apparatus as claimed in anyone of claims 1 to 5 wherein said mudgun is supported
on a trolley (TR).
7. An apparatus as claimed in anyone of claims 1 to 6 wherein said mudgun is operated
under operating pressure of 10 to 50 kg/cm".
8. An apparatus as claimed in anyone of claims 1 to 7 wherein said mudgun is provided
with temperature regulator means.
9. An apparatus as claimed in claim 8 wherein said temperature regulator is adapted to
control the temperature on the surface of the mudgun at 50 to 350°C.
10. An apparatus as claimed in anyone of claims 1 to 9 wherein said means simulating the
blast furnace taphole comprise heat resistant sleeve preferably detachable and splitted
into two parts along the length.
11. An apparatus as claimed in anyone of claims 1 to 10 wherein said detachable steel
sleeve is of stainless steel to withstand temperature of about 1100°C.
12. An apparatus as claimed in anyone of claims 1 to 11 wherein said chamber furnace
comprise exhaust means for passage of evolving gases.
13. An apparatus as claimed in claim 10 wherein said heat resistant sleeve at its open end
away from the mudgun is adapted to be relcasably closed by means of a ceramic plug.
14. An apparatus as claimed in anyone of claims 4 to 13 wherein said hydraulic means for
operation the mudgun comprising:
oil tank ;
pump means operatively connected to a motor ;
pressure control valve ;
How control valve ;
hydraulic cylinder ; and
pressure gauge.
15. An apparatus as claimed in anyone of claims 1 to 14 wherein said mudgun exit end is
maintained in alignment with the adjacent end of the heat resistant sleeve in said
furnace chamber.
16. An apparatus as claimed in anyone of claims 1 to 15 wherein clamp means is
provided for relcasably housing the heat resistant sleeve within the chamber furnafce.
17. An apparatus as claimed in anyone of claims 1 to 16 wherein said furnace chamber is
of dimension 200 x 200 x 200 mm while said heat resistant sleeve is of 350x350mm
inner dimension.
18. An apparatus as claimed in anyone of claims 1 to 17 wherein detachable electrical
heating means and control system are installed in the nose portion of the mudgun.
19. An apparatus as claimed in anyone of claim 18 wherein said detachable portion of
said mudgun over the metallic shell comprise insulating material cast along with the
heating coils.
20. An apparatus as claimed in anyone of claims 1 to 19 wherein a thermo couple is
inserted through the shell of the mudgun to control the temperature at the surface
between 5()-350°C.
21. An apparatus as claimed in anyone of claims 1 to 20 wherein said hydraulic means
comprise hydraulic cylinder obtained of stainless steel.
22. An apparatus for evaluation of (low characteristics and setting behaviour of blast
furnace laphole mass under simulated working conditions substantially as herein
described and illustrated with reference to the accompanying drawings.

An apparatus for evaluation of flow characteristics and setting behaviour of blast
furnace taphole mass under simulated working conditions. The apparatus
specifically utilizes a mudgun (MG), a chamber furnace (FC) having means for
simulating the taphole of the blast furnace and means for pushing the taphole
mass from said mudgun to said simulating means and means for observing the
flow characteristics/behaviour of the taphole mass under simulated conditions.
The apparatus is directed to assist predicting actual performance of taphole mass
in used in blast furnaces and would avoid the problems of inconsistent behaviour
of taphole mass and consequent loss of productivity.