Title of Invention

"A REAFACTORY COATED INJECTION LANCE OF AN EXTENDED OPPRATING LIFE"

Abstract A refractory coated injection lance of an extended operating life of 10-12 heats, being suitable for injecting mixture of solid reagents and carrier gases or gases alone at any desired depth of the hot metal bath in a ladle, and capable of being supported at the bath bottom for operating in a vibration-free manner, characterized in that the lance comprises a robust carbon steel pipe (1); a plurality of anchors (2) attached to the outer vertical surface of pipe (1) by welding at desired intervals, the anchors and pipe being covered with cushioning materials to overcome the effect of the difference in their thermal expansions; a coating of the mixture of monolithic refractory materials (3) around the lower part (AB) of the lance; a plurality of nozzles (6) protruding the lance body laterally near the lower part thereof, making only one or two of the said nozzles operative at a time; and lugs (4) fitted to the lance near its upper part for facilitating handling of the lance during its transfer from the lance stand to the heating bay and vice versa.
Full Text The invention relates to a refractory coated injection lance of an extended operating life suitable for use repeatedly in the pretreatment of hot metal and refining of steel by injecting a mixture of reagents and gases or only gases in the hot metal or steel bath.
To meet the increasing demand for metal and steel of stringent quality standard, the pretreatment of hot metal and refining of steel by following the injection process has become essential at present. In the injection process, a mixture of reagents and gases or gases alone are injected into the hot metal or steel bath by mixing them with a certain carrier gas in a vessel called 'Dispenser1. From the dispenser reagents are conveyed to an injection lance which is dipped into the hot molten metal or steel to release the mixture of reagents and gases ar gases alone at a desired depth inside the bath, generally at the maximum depth of the bath.
The drawbacks of a conventional lance are :
(i) it is not refractory coated;
(ii) it is not suitable for injecting solid reagents in the hot metal bath;
(iii) it is not suitable for injecting gases into the hot metal bath at any desired depth of the hot metal bath;
(iv) it is subject to appreciable vibrations during use;
(v) all of its nozzles are provided at the bottom surface thereof and to be used simultaneously; and
(vi) it is not reusable if one or more of its nozzles is blocked.
The object of the present invention is to provide an improved lance which is refractory coated, can be used for injecting a mixture of multiple solid reagents in powder or granular forms with carrier gases or gases alone at any desired depth of the hot metal bath, can be supported at the ladle bottom for minimising its vibration during use, is provided with multiple nozzles on its vertical surface at different heights from its bottom end to facilitate injection of reagents and gases at any desired depth of hot metal bath without getting choked easily, can be used repeatedly by making only 1 or 2 nozzles operative at a time and activating the remaining nozzles when the used nozzles are blocked and is provided with lifting lugs for facilitating its placement at the lance carriage or inside the heating furnace.
The improved lance has been constructed to have a maximum number of eight nozzles and make it suitable for use with :-
(a) depth of injection - 0.5m to 3.5m
(b) pressure of carrier gas" - 1.0 to 7.0 Kg/cm
(c) ratio of gas to solid
reagents injected - 4 lit/kg to 120 lit/kg
(d) particle size of solid
reagents injected - 100 microns to 1 mm
(e) minimum number of outlet
nozzles functioning at a
time - 1
(f) maximum number of outlet
nozzles functioning at a
time - 2
Thus the invention provides a refractory coated injection lance of an extended operating life of 10-12 heats being suitable for injecting mixture of solid reagents and carrier gases or gases alone at
any desired depth of the hot metal bath in a ladle, and capable
of being supported at the tafch. bottom in for operating a vibrat: ion-free manner,
characterised in that the lance comprises a robust carbon steel pipe; a plurality of anchors attached to the outer vertical surface of pipe by v/elding at desired intervals, the anchors and pipe being covered with cushioning materials to overcome the effect of the difference in their thermal expansions; a coating of the mixture of monolithic refractory materials around the lower part of the lance; a plurality of nozzles protruding the lance body laterally near the lower part thereof, making only one or two of the said nozzles operative at a time; and lugs fitted to the lance near its upper part for facilitating handling of the lance 'during its transfer from the lance stand to the heating bay and vice versa.
The construction of the invented injection lance is described with reference to the drawings accompanying the provisional specification and the revised fresh drawings accompanying the revised complete specification?in an unrestricted manner by v/ay of example only, in which -
Figure 1 shows the sectional sketch of the injection lance illustrating its main components'and an enlarged view of the bottom part of the injection lance.
In Fig. 1 of both the provisional and. revised complete specifications, a robust carbon steel pipe d) is provided at the centre of the lance for conveying the mixture of reagents and gases or gases alone supplied through a hose connected to the top of the lance by a coupling arrangement at (5) for injection into the hot metal bath through outlet nozzles (6) at the vertical side of the lance near its bottom part. A number of anchors (2) are attached to the outer vertical surface of pipe (1) by welding at predetermined intervale, the anchors and the pipe being covered with suitable cushioning materials such as scraps, coconut ropes, light v/ood chips etc. to overcome the effect of the difference in their thermal expansions. The portion of the lance length, marked (AB), is coated with a mixture of monolithic refractory materials (3)« Lugs (4) are fitted to the lance near its top part for facilitating its handling during its transfer from the lance stand to the heating bay and from the heating bay to the lance stand.
The outlet nozzles (6) are arranged in a straight line across the lance body near its bottom part to facilitate their cleaning for repeated applications of the lance. Upto a maximum of eight outlet nozzles can be provided in the lance although not more than two of these are allowed to be operational at a time. The remaining outlet nozzles are put into action when the nozzles already used get damaged or blocked. An enlarged view (A1) of bottom portion of the lance is given in Fig. 1 of revised complete specification. This ensures an extended operating life of the invented lance compared with a conventional lance. The other
merits of the invented lance are :- (i) it can be used for injecting multiple solid reagents such as mixture of finely powdered lime, sodaash, calcium carbide and magnesium carbide, (ii) it can be used for injecting both gases and mixture of gases and said solid reagents, (iii) it is capable of being positioned is a vibration-free manner at the bottom of the hot metal bath to facilitate precise control of the depth of the location inside the bath where the injection of the mixture of reagents and gases or gases alone take place and (iv) it is provided with lugs to facilitate its handling during transfer from the lance stand to the heating bay and vice versa.




We Claim :-
1. A refractory coated injection lance of an extended
operating life of 10-12 heats compared with normal 4-6 heats,
being suitable for injecting mixture of solid reagents and
carrier gases or gases alone at any desired depth of the hot
metal bath in a ladle, and capable of being supported at the
bottom in a vibration-free manner, characterised in that the
lance comprises a robust carbon steel pipe d); a plurality of
anchors (2) attached to the outer vertical surface of pipe d)
by welding at desired intervals, the anchors and pipe being
covered with cushioning materials to overcome the effect of the
difference in their thermal expansions; a coating of the mixture
of monolithic refractory materials (3) around the lower part (AB)
of the lance; a plurality of nozzles (6) protruding the lance
body laterally near the lower part thereof, making only one or
two of the said nozzles operative at a time; and lugs (4) fitted
to the lance near its upper part for facilitating -handling of the
lance during its transfer from the lance stand to the heating bay
and vice versa.
2. The lance as claimed in claim 1, wherein the total
number of nozzles provided is two to eight.
3. A refractory coated injection lance of an extended
operating life substantially as described herein and illustrated
in the drawings accompanying the complete and provisional
specifications.

Documents:

506-del-1995-abstract.pdf

506-del-1995-claims.pdf

506-del-1995-correspondence-others.pdf

506-del-1995-correspondence-po.pdf

506-del-1995-description (complete).pdf

506-del-1995-description (provisional).pdf

506-del-1995-drawings.pdf

506-del-1995-form-1.pdf

506-del-1995-form-2.pdf

506-del-1995-form-4.pdf

506-del-1995-form-6.pdf

506-del-1995-gpa.pdf

abstract.jpg


Patent Number 189679
Indian Patent Application Number 506/DEL/1995
PG Journal Number 31/2009
Publication Date 31-Jul-2009
Grant Date 27-Jan-2004
Date of Filing 21-Mar-1995
Name of Patentee STEEL AUTHORITY OF INDIA LIMITED
Applicant Address ISPAT BHAWAN, LODI ROAD, NEW DELHI-110003.
Inventors:
# Inventor's Name Inventor's Address
1 OM PRAKASH SHARMA AGM RDCIS/SAIL
2 PREM KUMAR TRIPATHI, PRM RDCIS/SAIL
3 SUSHANTO SARKAR, PRE RDCIS/SAIL
PCT International Classification Number C229/05
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA