Title of Invention	A METHOD OF PUMPING MOLTEN ZINC OVER A DISTANCE
Abstract	A method of pumping molten zinc over a distance during pot change-over in continuous galvanizing lines comprising the steps of pumping out zinc from the pot and removing all fixed devices above the pot and removing the pot, repairing the refractory surrounding the pot and curing the refractory. The new pot is then put on the repaired refractory. The molten zinc is then pumped from an adjacent continuous galvanizing line through a pipe line to said new pot using a zinc pump wherein, a ceramic fibre blanket of about 100 mm thickness and density of 96 kg / m3 is put around the zinc flow pipe to maintain the flow without chilling down inside the pipe.

Title of Invention

A METHOD OF PUMPING MOLTEN ZINC OVER A DISTANCE

Abstract

A method of pumping molten zinc over a distance during pot change-over in continuous galvanizing lines comprising the steps of pumping out zinc from the pot and removing all fixed devices above the pot and removing the pot, repairing the refractory surrounding the pot and curing the refractory. The new pot is then put on the repaired refractory. The molten zinc is then pumped from an adjacent continuous galvanizing line through a pipe line to said new pot using a zinc pump wherein, a ceramic fibre blanket of about 100 mm thickness and density of 96 kg / m3 is put around the zinc flow pipe to maintain the flow without chilling down inside the pipe.

Full Text	FIELD OF APPLICATION The present invention relates generally to a method for pumping molten zinc over a distance. In particular, it relates to transferring molten zinc at a temperature of 465° C over a distance from one existing pot to another pot being commissioned. Such transfer of molten zinc from an existing heated pot will help cutting down the idle-time for heating zinc ingots from the ambient to the molten stage. BACKGROUND OF THE INVENTION In continuous galvanizing lines of cold rolling mills for coating heated cold rolled strip to produce galvanized strip, an iron pot is used as a container for molten zinc. This pot contains about 100 tons of molten zinc at any given point of time. This pot needs to be changed when the refractory thickness fails below a critical value or when a sudden leakage develops therein. The pot change-over is a time consuming process. One full day is required for pumping out zinc from the pot and for removing all fixed devices above the pot. Removing the pot itself may take a full working day. Repairing the refractory surrounding the pot, curing it and putting a new pot on the repaired refractory may take two more days. Slow ramped heating of the pot can then be started for melting the solid zinc ingots put in the new pot and preparing a bath of liquid zinc at 465° C. This process may take as much as five days. Finally, one day will be needed to put all the pot equipment in place and start the galvanizing line. The whole process of changing the pot thus needs about ten days to complete. A need was therefore, felt to cut down on this down time and the resultant loss of production from the continuous galvanizing line. SUMMARY OF THE INVENTION Thus the main object of the present invention is to reduce the idle time in a continuous galvanizing line during a pot change-over process. Another object of the present invention is to cut down the cost of the pot change-over process. These and other objects are achieved by eliminating the time required for melting the solid zinc in a newly commissioned pot by stow ramped heating and preparing a bath of molten zinc at 465° C. Molten zinc can be transferred from an existing heated pot of another continuous galvanized line to the newly commissioned pot. Such an existing galvanizing line may be some distance away from the galvanizing line being commissioned with a new pot. It should be noted that the solidification temperature of liquid zinc is 420° C. While transferring molten zinc from the heated pot through a pipeline, care should be taken to see that the first flow of metal at a temperature of 460° C to 465° C does not chill down inside the pipe length. The pipe length may be about 30 to 35 m. Such chilling down may result in stoppage of metal flow through the pipe. The pipe length to be used for the transfer of molten zinc for the existing heated pot may therefore, need some special designed features. Thus the present invention provides a method for pumping molten zinc over a distance during pot change-over in continuous galvanizing lines, comprising the steps of pumping out zinc from the pot, and removing all fixed devices above the pot; removing the pot, repairing the refractory surrounding the pot, and curing the refractory; putting a new pot on the repaired refractory; and pumping in molten zinc from an adjacent continuous galvanizing line through a pipe line to said new pot using a zinc pump. DETAILED DESCRIPTION Figure 1 of the accompanying drawing shows arrangement used for transporting molten zinc at 470° C. For pumping the zinc, the existing liquid zinc pump capacity and its need and flow should also be considered. It should be able to maintain the required flow rate for a distance of 30 to 35 meters (the distance between an existing heated pot of molten zinc and the newly replaced pot). The head should also be adequate with respect to the pot positions. The maximum possible gradient available based on the shop floor equipment positions should be aiiowed to the configuration, The pipe dimension required should be worked out based on calculations as well as past experience of pumping zinc across a distance so that there is minimum restriction on the flow path. A 100 mm NB pipe can be used for pumping zinc. This is based on calculations on past experience of pumping zinc across distances less than 10 meters. In order to maintain the first flow of metal thorough the pipe length at a temperature of 460° C without chilling down inside the pipe abng its length, a ceramic fibre blanket of about 100 mm thickness and density of 96 kg / m3 can be put around the zinc flow pipe. This pipe itself being housed within a bigger steel pipe of 300 mm diameter. The pot temperature profile to be maintained to accept molten metal at 460° should also be studied. A 16 hour slow heating of the carrier pipe with gas burner can be employed to take the inner pipe to a temperature of around 250° C. Simultaneously, a 16 hour heat cycle for heating the new pot can be employed to soak the pot at a temperature of 400° C, to receive the molten zinc at 460° C. Layers of zinc ingots can be built up at the periphery and on the floor inside the new pot to reduce the impact of large amount of molten zinc at 460° C. It would also be necessary to ascertain a suitable date for pumping molten zinc for the adjacent galvanizing line so that the nearest pot will have the same type of zinc chemistry as required for the newly commissioned line. Thus according to the present invention, the changeover of the pot can be carried out in the following steps: Pumping out zinc from the pot to the leakage mould, and removing all fixed devices above the pot. This will take one day. Removing the pot, repairing the refractory surrounding the pot, and curing it. This will take another working day. Putting the new pot on the repaired refractory. This process will take one day. Pumping in liquid zinc from an adjacent continuous galvanizing line. For pumping around 70 tons from an auxiliary pot 35 meters away takes about 25 minutes. Thus, in the present invention, the continuous galvanizing line can start functioning on the fifth day itself, saving more than four days production time during each changeover of pot in a continuous galvanizing line. WE CLAIM 1. A method of pumping molten zinc over a distance during pot change-over in continuous galvanizing lines, comprising the steps of: - pumping out zinc from the pot and removing all fixed devices above the pot; - removing the pot, repairing the refractory surrounding the pot, and curing the refractory; - putting a new pot on the repaired refractory; characterized in that, - the molten zinc is pumped from an adjacent continuous galvanizing line through a pipe line to said new pot using a zinc pump wherein a ceramic fibre blanket of about 100 mm thickness and density of 96 kg / m3 is put around the zinc flow pipe to maintain the flow without chilling down inside the pipe. 2. The method as claimed in claim 1, wherein a pipe of 100 mm NB is used to pump 70 tons of molten zinc from an auxiliary pot 35 meters away in about 25 minutes. 3. The method as claimed in claim 1 or 2, wherein the said pipe line is housed within a pipe of about 300 mm diameter. 4. The method as claimed in claims 1 to 3, wherein for taking the inner pipe to a temperature of about 250° C, the carrier pipe is subjected to slow heating with gas burner, over a 16 hour period. 5. The method as claimed in claims 1 to 4, wherein for soaking the new pot at a temperature of 400° C to receive molten zinc at 460° C, a 16 hour heat cycle is employed simultaneously with heating of said carrier pipe. A method of pumping molten zinc over a distance during pot change-over in continuous galvanizing lines comprising the steps of pumping out zinc from the pot and removing all fixed devices above the pot and removing the pot, repairing the refractory surrounding the pot and curing the refractory. The new pot is then put on the repaired refractory. The molten zinc is then pumped from an adjacent continuous galvanizing line through a pipe line to said new pot using a zinc pump wherein, a ceramic fibre blanket of about 100 mm thickness and density of 96 kg / m3 is put around the zinc flow pipe to maintain the flow without chilling down inside the pipe.

Full Text

FIELD OF APPLICATION
The present invention relates generally to a method for pumping molten zinc over a
distance. In particular, it relates to transferring molten zinc at a temperature of 465° C
over a distance from one existing pot to another pot being commissioned. Such
transfer of molten zinc from an existing heated pot will help cutting down the idle-time
for heating zinc ingots from the ambient to the molten stage.
BACKGROUND OF THE INVENTION
In continuous galvanizing lines of cold rolling mills for coating heated cold rolled strip
to produce galvanized strip, an iron pot is used as a container for molten zinc.
This pot contains about 100 tons of molten zinc at any given point of time. This pot
needs to be changed when the refractory thickness fails below a critical value or when a
sudden leakage develops therein.
The pot change-over is a time consuming process. One full day is required for pumping
out zinc from the pot and for removing all fixed devices above the pot.
Removing the pot itself may take a full working day. Repairing the refractory
surrounding the pot, curing it and putting a new pot on the repaired refractory may
take two more days.

Slow ramped heating of the pot can then be started for melting the solid zinc ingots put
in the new pot and preparing a bath of liquid zinc at 465° C. This process may take as
much as five days.
Finally, one day will be needed to put all the pot equipment in place and start the
galvanizing line. The whole process of changing the pot thus needs about ten days to
complete.
A need was therefore, felt to cut down on this down time and the resultant loss of
production from the continuous galvanizing line.
SUMMARY OF THE INVENTION
Thus the main object of the present invention is to reduce the idle time in a continuous
galvanizing line during a pot change-over process.
Another object of the present invention is to cut down the cost of the pot change-over
process.
These and other objects are achieved by eliminating the time required for melting the
solid zinc in a newly commissioned pot by stow ramped heating and preparing a bath of
molten zinc at 465° C.
Molten zinc can be transferred from an existing heated pot of another continuous
galvanized line to the newly commissioned pot. Such an existing galvanizing line may
be some distance away from the galvanizing line being commissioned with a new pot.

It should be noted that the solidification temperature of liquid zinc is 420° C. While
transferring molten zinc from the heated pot through a pipeline, care should be taken
to see that the first flow of metal at a temperature of 460° C to 465° C does not chill
down inside the pipe length. The pipe length may be about 30 to 35 m. Such chilling
down may result in stoppage of metal flow through the pipe.
The pipe length to be used for the transfer of molten zinc for the existing heated pot
may therefore, need some special designed features.
Thus the present invention provides a method for pumping molten zinc over a distance
during pot change-over in continuous galvanizing lines, comprising the steps of
pumping out zinc from the pot, and removing all fixed devices above the pot; removing
the pot, repairing the refractory surrounding the pot, and curing the refractory; putting
a new pot on the repaired refractory; and pumping in molten zinc from an adjacent
continuous galvanizing line through a pipe line to said new pot using a zinc pump.
DETAILED DESCRIPTION
Figure 1 of the accompanying drawing shows arrangement used for transporting molten
zinc at 470° C.
For pumping the zinc, the existing liquid zinc pump capacity and its need and flow
should also be considered. It should be able to maintain the required flow rate for a
distance of 30 to 35 meters (the distance between an existing heated pot of molten zinc
and the newly replaced pot).

The head should also be adequate with respect to the pot positions. The maximum
possible gradient available based on the shop floor equipment positions should be
aiiowed to the configuration,
The pipe dimension required should be worked out based on calculations as well as past
experience of pumping zinc across a distance so that there is minimum restriction on
the flow path. A 100 mm NB pipe can be used for pumping zinc. This is based on
calculations on past experience of pumping zinc across distances less than 10 meters.
In order to maintain the first flow of metal thorough the pipe length at a temperature of
460° C without chilling down inside the pipe abng its length, a ceramic fibre blanket of
about 100 mm thickness and density of 96 kg / m3 can be put around the zinc flow
pipe. This pipe itself being housed within a bigger steel pipe of 300 mm diameter.
The pot temperature profile to be maintained to accept molten metal at 460° should
also be studied.
A 16 hour slow heating of the carrier pipe with gas burner can be employed to take the
inner pipe to a temperature of around 250° C.
Simultaneously, a 16 hour heat cycle for heating the new pot can be employed to soak
the pot at a temperature of 400° C, to receive the molten zinc at 460° C.
Layers of zinc ingots can be built up at the periphery and on the floor inside the new
pot to reduce the impact of large amount of molten zinc at 460° C.

It would also be necessary to ascertain a suitable date for pumping molten zinc for the
adjacent galvanizing line so that the nearest pot will have the same type of zinc
chemistry as required for the newly commissioned line.
Thus according to the present invention, the changeover of the pot can be carried out
in the following steps:
Pumping out zinc from the pot to the leakage mould, and removing all fixed
devices above the pot. This will take one day.
Removing the pot, repairing the refractory surrounding the pot, and curing it.
This will take another working day.
Putting the new pot on the repaired refractory. This process will take one
day.
Pumping in liquid zinc from an adjacent continuous galvanizing line. For
pumping around 70 tons from an auxiliary pot 35 meters away takes about
25 minutes.
Thus, in the present invention, the continuous galvanizing line can start functioning on
the fifth day itself, saving more than four days production time during each changeover
of pot in a continuous galvanizing line.

WE CLAIM
1. A method of pumping molten zinc over a distance during pot change-over
in continuous galvanizing lines, comprising the steps of:
- pumping out zinc from the pot and removing all fixed devices above the
pot;
- removing the pot, repairing the refractory surrounding the pot, and curing
the refractory;
- putting a new pot on the repaired refractory;
characterized in that,
- the molten zinc is pumped from an adjacent continuous galvanizing line
through a pipe line to said new pot using a zinc pump wherein a ceramic
fibre blanket of about 100 mm thickness and density of 96 kg / m3 is put
around the zinc flow pipe to maintain the flow without chilling down inside
the pipe.

2. The method as claimed in claim 1, wherein a pipe of 100 mm NB is used
to pump 70 tons of molten zinc from an auxiliary pot 35 meters away in
about 25 minutes.
3. The method as claimed in claim 1 or 2, wherein the said pipe line is
housed within a pipe of about 300 mm diameter.

4. The method as claimed in claims 1 to 3, wherein for taking the inner pipe
to a temperature of about 250° C, the carrier pipe is subjected to slow
heating with gas burner, over a 16 hour period.
5. The method as claimed in claims 1 to 4, wherein for soaking the new pot
at a temperature of 400° C to receive molten zinc at 460° C, a 16 hour
heat cycle is employed simultaneously with heating of said carrier pipe.

A method of pumping molten zinc over a distance during pot change-over in
continuous galvanizing lines comprising the steps of pumping out zinc from the
pot and removing all fixed devices above the pot and removing the pot, repairing
the refractory surrounding the pot and curing the refractory. The new pot is
then put on the repaired refractory. The molten zinc is then pumped from an
adjacent continuous galvanizing line through a pipe line to said new pot using a
zinc pump wherein, a ceramic fibre blanket of about 100 mm thickness and
density of 96 kg / m3 is put around the zinc flow pipe to maintain the flow
without chilling down inside the pipe.

Documents:

96-KOL-2005-ABSTRACT 1.1.pdf

96-kol-2005-abstract.pdf

96-KOL-2005-AMANDED CLAIMS.pdf

96-KOL-2005-CORRESPONDENCE-1.1.pdf

96-kol-2005-correspondence.pdf

96-kol-2005-correspondence1.2.pdf

96-KOL-2005-DESCRIPTION (COMPLETE) 1.1.pdf

96-kol-2005-description (complete).pdf

96-kol-2005-description (provisional).pdf

96-KOL-2005-DRAWINGS 1.1.pdf

96-kol-2005-drawings.pdf

96-KOL-2005-EXAMINATION REPORT REPLY RECIEVED.pdf

96-kol-2005-examination report.pdf

96-KOL-2005-FORM 1-1.1.pdf

96-kol-2005-form 1.pdf

96-kol-2005-form 13.pdf

96-kol-2005-form 18.1.pdf

96-kol-2005-form 18.pdf

96-KOL-2005-FORM 2-1.1.pdf

96-kol-2005-form 2.pdf

96-kol-2005-form 3.1.pdf

96-kol-2005-form 3.pdf

96-kol-2005-form 5.1.pdf

96-kol-2005-form 5.pdf

96-kol-2005-gpa.pdf

96-kol-2005-gpa1.1.pdf

96-KOL-2005-GRANTED FORM 2.1.pdf

96-kol-2005-granted-abstract.pdf

96-kol-2005-granted-claims.pdf

96-kol-2005-granted-description (complete).pdf

96-kol-2005-granted-drawings.pdf

96-kol-2005-granted-form 1.pdf

96-kol-2005-granted-specification.pdf

96-KOL-2005-OTHERS.pdf

96-KOL-2005-PA.pdf

96-kol-2005-reply to examination report.pdf

96-kol-2005-specification.pdf

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Patent Number

249915

Indian Patent Application Number

96/KOL/2005

PG Journal Number

47/2011

Publication Date

25-Nov-2011

Grant Date

23-Nov-2011

Date of Filing

14-Feb-2005

Name of Patentee

TATA STEEL LIMITED

Applicant Address

RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION JAMSHEDPUR

Inventors:

#	Inventor's Name	Inventor's Address
1	GANESH, P.S.S.	TATA STEEL LIMITED. RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION JAMSHEDPUR-831 001
2	MATHEW SAJI	TATA STEEL LIMITED. RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION JAMSHEDPUR-831 001
3	DHIR, SANDIP	TATA STEEL LIMITED. RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION JAMSHEDPUR-831 001
4	SHARMA, PANKAJ	TATA STEEL LIMITED. RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION JAMSHEDPUR-831 001
5	SHARMA, M.S.S.	TATA STEEL LIMITED. RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION JAMSHEDPUR-831 001
6	CHATTERJEE, AMIT	TATA STEEL LIMITED. RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION JAMSHEDPUR-831 001
7	CHAKRABARTI, SHANTANU	TATA STEEL LIMITED. RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION JAMSHEDPUR-831 001

PCT International Classification Number

C01G 9/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA