Inland Steel Company v the Broken Hill Proprietary Company Limited

[1992] APO 65

official notice

decision of a delegate of the commissioner of patents

Application        :    No. 584419 in the name of INLAND STEEL

COMPANY

Title:    Method and Apparatus for Adding Solid

Alloying Ingredients to Molten Metal

Stream

Action: Opposition under S.59 by THE BROKEN

HILL PROPRIETARY COMPANY LIMITED

Decision:    Issued            .  Specification

does not comply with s.40; time to

amend specification allowed.

patents act 1990

decision of a delegate of the commissioner of patents

Re:Patent Application No. 584419 by INLAND STEEL COMPANY and

opposition by THE BROKEN HILL PROPRIETARY COMPANY LIMITED

under Section 59 of the Patents Act 1952

background

Patent application 584419 by Inland Steel Company (Inland) was advertised accepted on 25 May 1989. On 24 August 1989 The Broken Hill Proprietary Company Limited (BHP) lodged a notice of opposition to the application under sec 59 of the Patents Act 1952. Evidence in support of the opposition was served on 3 April 1991 after BHP had obtained a number of unopposed extensions of time. After itself obtaining a number of unopposed extensions of time, Inland advised the Office through its patent attorney that it did not propose to lodge evidence in answer.

A hearing to determine the opposition was held in Melbourne on 13 August 1992.  Inland was represented by Ms Ann Slater, assisted by Mr Peter Heathcote, patent attorneys with Shelston Waters, and BHP was represented by Mr Greg Munt, patent attorney with Griffith Hack & Co.

THE SPECIFICATION

The specification states that the invention relates generally to the addition of solid alloying ingredients to molten metal, and more particularly to the addition of solid, particulate alloying ingredients to a stream of molten metal descending from an upper container to a lower container. 

One previously contemplated procedure for adding these alloying ingredients to molten steel comprises injecting solid particles of the ingredients into a descending stream of molten metal contained within and completely filling the cross-section of an elongated conduit extending between and communicating with both the ladle and the tundish.  The solid particles are mixed with a transport gas, and the mixture is introduced into the descending stream of molten metal through an injection port in the conduit.

However a number of problems can arise should this procedure be employed.  For example, the molten metal can back up through the injection port, the solid particles can be delivered in pulses rather than uniformly and there can be a plugging of the injection nozzle.

The specificatio'ns solution to these problems is to initially direct the molten metal descending from the upper container or ladle through an elongated, vertically disposed conduit having a lower end located above the top of the bath of molten metal forming in the lower container or tundish.  The elongated conduit, as well as that part of the descending stream located below the lower end of the conduit, are enclosed within an elongated, vertically disposed shroud having walls laterally spaced from the conduit and from the descending stream to define an unfilled, annular space between (a) the shroud and (b) the conduit and descending stream.  The cross-sectional area of the interior of the shroud is greater than the cross-sectional area of the interior of the conduit.  The shroud protects its interior and the contents thereof (i.e. the conduit and the descending stream) from the outside atmosphere surrounding the shroud.

The shroud and the conduit are both composed of refractory material.  The shroud has a lower end which extends below the top of the bath of molten metal in the lower container.  This helps to seal the interior of the shroud from the outside atmosphere surrounding the shroud.

The specification then indicates that the flow of the molten metal stream descending from the lower end of the conduit into the shroud preferably creates a low pressure region in the shroud having a pressure less than that of the outside atmosphere surrounding the shroud.  This low pressure region extends from the top of the bath of molten metal in the tundish up to the lower end of the conduit and above.

A mixture of solid, particulate alloying ingredient and transport gas is directed into the shroud and then into the interior of the descending stream, at a location below the lower end of the conduit and above the top of the bath, in the low pressure region.  This is accomplished by providing the shroud with an injection port located preferably at a level below the lower end of the conduit and/or angled downwardly and inwardly so as to direct the mixture of alloying ingredient and transport gas into the stream of molten metal at a location below the lower end of the conduit.

The specification then goes on to explain that enclosing the conduit and the descending stream within a shroud having inside walls laterally spaced from the conduit and the descending stream, and creating a low pressure region within the shroud, avoids the following, all of which are undesirable: backup of molten metal through the shroud injection port, pulsing delivery of solid addition material, uneven solid addition rates, liquid contact with the injection port and plugging of the injection port.  

The specification ends with thirty-four claims, of which claims 1 and 27 are independent claims and read as follows:

"1.  In a process wherein molten metal descends in a vertical
     stream from an upper container to a lower container, a
     method for adding solid particles of an alloying ingredient
     to said stream, said method comprising the steps of:

directing said descending stream initially through an
     elongated, vertically disposed conduit having a lower
     end;

forming a bath of said molten metal in said lower
     container;

positioning the lower end of said conduit above the top
     of said bath;

enclosing said conduit and said descending stream within
      elongated, vertically disposed solid, tubular shroud
     having walls laterally spaced from the conduit and the
     descending stream to define an unfilled, annular space
     between (a) the shroud and (b) the conduit and
     descending stream;

the cross-sectional area of the interior of said shroud
     being greater than the cross-sectional area of the
     conduit's interior;

protecting the interior of said shroud and the contents
     thereof from the outside atmosphere surrounding said
     shroud;

providing a mixture containing a transport gas and solid
     particles of an alloying ingredient;

and directing said mixture into said shroud and into the
     interior of said descending stream, at a stream location
     below the lower end of the conduit and above the top of
     the bath.

27. A device for use in adding solid particles of an alloying
     ingredient to molten metal, said device comprising:

a vertically disposed, elongated conduit having a lower
     end;

vertically disposed shroud for said conduit, said shroud
     having walls located around the outside of and laterally
     spaced from said conduit to define an unfilled, annular
     space therebetween;

the cross-sectional area of the shroud's interior being
     greater than the cross-sectional area of the conduit's
     interior;

said shroud having a lower end terminating below the
     lower end of said conduit, there being an unobstructed,
     columnar, vertical space within the shroud and extending
     between said two lower ends;

said columnar space having a center line;

said conduit comprising means for directing a descending
     stream of molten metal downwardly into said columnar
     space along the center line thereof and laterally spaced
     from the walls of said shroud;

an injection port in said shroud above said lower end
     thereof;

said injection port comprising means for directing a
     mixture of gas and solid particles into the interior of
     a descending stream of molten metal inside said shroud,
     at a location below the lower end of the conduit and
     above the lower end of the shroud."

THE EVIDENCE

The evidence in support of the opposition consists of a statutory declaration by David Lyle Webster accompanied by two exhibits.  As indicated above, no evidence in answer was lodged.  I will discuss the relevant parts of the supporting evidence where appropriate in my decision.

DECISION

The notice of opposition lists all grounds available under sub-sec 59(1).  At the hearing Mr Munt indicated that only the grounds of obviousness, lack of novelty and non-compliance with sec 40 would be pursued.

Obviousness

The question of obviousness involves an investigation of whether the invention would have been obvious to a non-inventive skilled worker in the field equipped with the common general knowledge as at the priority date (see Wellcome Foundation Limited v VR Laboratories (Aust) Pty Ltd (1982) RPC 343). Thus a consideration of the question of obviousness must be made against the background of the common general knowledge in the art in Australia. Guidance as to what constitutes such knowledge may be found in Minnesota Mining and Manufacturing Co v Beirersdorf (Australia) Ltd (1980) 144 CLR 253.

Mr Munt submitted that significant weight should be placed on the statements made by Mr Webster as to the state of the common general knowledge in view of his expertise in the field of the invention and BHP's predominance in that field in Australia.  He also pointed out that Inland had not lodged any evidence which contested the evidence in support.  While acknowledging BHP's standing in the steel making industry in Australia, Ms Slater argued that Mr Webster is not a skilled but non-inventive worker in the relevant field as required by the case law on obviousness and, consequently, his evidence is of little or no probative value.

Mr Webster deposes that he is an honours graduate in metallurgy from Newcastle University.  He joined BHP in 1970, and in the period 1979 to August 1985 was responsible for developments in certain steel making practices.  Since then he has had quite a deal of experience in relation to bloom caster commissioning and technology development, and at the time of making his declaration was responsible for all aspects of bloom caster operations and maintenance.

Taking account of the information placed before me on this matter, including the nature of the invention, I consider that the non-inventive skilled worker in the present circumstances is a person having "intermediate" technical skills as per Graham J in American Cyanamid Company v Ethicon Limited [1979] RPC 215 at page 246. I therefore accept Mr Munt's submission that Mr Webster is an appropriately skilled worker in the field of the invention.

I now have to take into consideration what has been established by the evidence as common general knowledge in the field of the invention at the priority date of the claims.  In his declaration Mr Webster expresses the opinion that the method and apparatus disclosed by the present application are to a large extent in accordance with conventional technology well known in Australia for the addition of solid alloying ingredients.  He then proceeds as follows:

"7.  The teeming stage that has been in commercial use at the Newcastle Steelworks of BHP Steel Rod and Bar Products Division for many years before the priority date of the patent application comprised:

(a) a cluster of ingot moulds, and

(b) a ladle for transporting molten steel from the
    B.O.S. to the ingot moulds, the ladle having a
    nozzle in the bottom.

In the context of the patent application, the ladle is an "upper container", each ingot mould is a "lower container", and the nozzle is an "elongated, vertically disposed conduit having a lower end".

In use, the ladle is positioned by an overhead crane above an ingot mould and molten steel from the ladle pours through the nozzle into the ingot mould.  Attached hereto as Exhibit DLW-1 is a copy of the front page and page 19 of an information booklet entitled "The Making of Iron and Steel" prepared by BHP for use by students and trainees as an introduction to steelmaking technology which was published in June, 1977.  It will be noted that Fig. 12 on page 19 schematically illustrates the foregoing ingot mould teeming procedure.

In order to add lead or other solid alloying ingredients to the molten steel from the B.O.S., it has been the practice for many years before the priority date of the patent application to inject the solid alloying ingredients into the downwardly flowing stream of molten metal in the gap between the ladle nozzle and the ingot mould.

8.  Attached hereto as Exhibit DLW-2 is a copy of Australian patent application 80905/82 entitled "Manufacture of Continuously Cast Leaded Free Machining Steel" in the name of Mitsubishi Steel Mfg. Co., Ltd. (the "Mitsubishi patent application"), which I am informed was published in Australia by the Australian Patent Office on October 28, 1982, some 2 years before the priority date of the patent application.  The patent application discloses a method of manufacturing leaded, free-cutting steel.

The Mitsubishi patent application is of interest since the "Background of the Invention" on pages 1a to 3 of the patent application discloses that conventionally one option for manufacturing leaded, free-cutting steel is to inject shots of lead or lead alloy into molten metal as it is being poured from a ladle into an ingot mould.  This disclosure is consistent with the discussion in clause 7 above of the teeming stage at the Newcastle Steelworks of BHP Steel Rod and Bar Products Division."

Mr Webster then alleges that in view of the foregoing analysis the only difference between the method and apparatus of the present application and what was known in Australia before the priority date of the present application is the use of a shroud
to enclose the conduit and the downwardly directed stream of molten metal flowing from the upper container to the lower container.  To this end he states:

"10. The patent application indicates that one function of the shroud is to protect the interior of the shroud and the contents thereof from the outside atmosphere surrounding the shroud.  However, one inevitable and in many respects more important consequence in the case of injection of toxic solid alloying ingredients of such a construction is to completely prevent the escape of fumes generated as the solid alloying ingredients are injected into the downwardly flowing stream of molten steel.  Thus, the only source of fumes that would be of concern in the case of the addition of toxic solid alloying ingredients, is from that part of the surface of the molten metal bath in the lower container that is not enclosed by the shroud.

11. The use of "shrouds", with or without fume extraction from the shrouds, is well known in the steel industry and other industries in general.  For example, I note that Fig. 1 of the Mitsubishi patent application discloses the use of a hood 7 to enclose the gap between an upper container 3 and a lower container 5 and to extract fumes generated in the gap.  In addition, I note that the teeming stage that has been in commercial use at the Newcastle Steelworks of BHP Steel Rod and Bar Products Division for many years before the priority date of the patent application comprises exhaust hoods to extract fumes generated during pouring of molten metal from the ladle into the ingot moulds.

12. Further to clause 11 above, thus in effect the use of "shrouds", with or without fume extraction from the shrouds, is one option for fume control that was well known in the steel making industry before the priority date of the patent application."

Thus what Mr Webster in essence appears to be suggesting is that the claimed invention differs only in matters of common general knowledge from what is known to him in the field as exemplified by the disclosures of the Mitsubishi patent application and the BHP information booklet attached as exhibits to his declaration.  However it seems to me that this suggestion is based on ex post facto reasoning, an approach which has been criticised in many courts (see Palmer v Dunlop Perdriau Rubber Company Limited (1937) 59 CLR 30, British Acoustic Films Ltd v Nettlefold Productions (1936) 53 RPC 221 and British Westinghouse Electric and Manufacturing Co Ltd v Braulik (1910) 27 RPC 209). Quoting from Palmer v Dunlop (supra):

"It is frequently possible to take, as it were, a patent to pieces, and then, beginning with one piece, to show how, in order to obtain one result, step A must be taken; in order to obtain another particular result, step B must be taken - and so on until one has the whole combination for which inventive quality is claimed.  If the analysis is taken into sufficient detail, every single step in the development of an invention, taken separately, can be shown to be obvious. ......

But, in the present case, the evidence of the expert witnesses for the defendant is really a reconstruction of an inventive process step by step, each step, when it is known that it must be taken in a certain direction, being obvious enough in itself."

Ms Slater submitted that Mr Webster's evidence is insufficient to prove the state of the common general knowledge in the field of the invention.  I would be inclined to agree with this submission if the evidence relied solely upon the disclosures of the exhibits to his declaration.  In this regard I note from the evidence that the BHP information booklet was prepared for use by "students and trainees" who could not be regarded as appropriately skilled workers in the field.  In any event, it should be remembered that the fact that a book may have been available on a library shelf or in circulation does not itself mean that it can be regarded as common general knowledge (Riekie & Anor v M J McGrath Pty Ltd & Anor (1986) AIPC 90-311 and British Acoustic Films v Nettlefold (supra)).  I also note that the evidence fails to establish that the Mitsubishi patent application was part of the common general knowledge in the field as per Aickin J in Minnesota Mining and Manufacturing v Bierersdorf (supra) at page 295.

However it seems to me that Mr Webster's evidence primarily stems from knowledge acquired by him through considerable experience in the steel making industry in Australia and so, in the absence of any evidence to the contrary, I am prepared to accept that the features individually referred to by Mr Webster are well known in the field.

Nevertheless, it must be remembered that the claimed invention is directed to a particular combination of features.  As pointed out by Ms Slater, where a combination patent is involved, it must be shown that it would have been obvious to not only select  the separate integers which make up that combination, but also to select the particular combination of those integers in question (Minnesota Mining and Manufacturing v Bierersdorf (supra)).In the present case the evidence before me does not establish that it would have been obvious for a so-called non-inventive skilled worker, in searching for a solution to  problems such as pulsed delivery encountered with the known procedure for adding solid alloying ingredients to molten steel, to arrive without the advantage of hindsight at the particular combination of features defined.It should be noted here that although Mr Webster has discussed the common usage of "shrouds" (hoods) in the steel industry and other industry in general, the claimed invention does not simply lie in a shroud per se, or in the mere use of a shroud.

On the basis of the foregoing, I find that BHP has not provided sufficient evidence to establish the ground of obviousness.

Novelty

This ground was argued on the basis of the declaratory evidence lodged in support of the opposition, rather than direct evidence
of prior documentary publication or prior use.

The test for novelty is whether an alleged anticipation is the same in substance as the claim in suit so that the alleged anticipation would, if the patent were valid, constitute an infringement (Nicaro Holdings Pty Ltd v Martin Engineering (1990) 91 ALR 513 and R D Werner & Co Inc v Bailey Aluminium Products Pty Ltd 85 ALR 679). This test is commonly referred to as the reverse infringement test which was formulated by Aickin J in Meyers Taylor Pty Ltd v Vicarr Industries Limited (1977) 137 CLR 228 at page 235.

AU Patent Application 80905/82

The Mitsubishi patent application, whose date of publication in Australia is as stated by Mr Webster, relates to the production of leaded free-cutting steel in a continuous casting process in which lead or lead alloy is added directly to molten steel in a "lower container" (mould 5) while pouring the molten metal from an "upper container" (tundish 3).  Toxic fumes or gases generated during this process are forced into a "shroud" (hood 7) arranged to cover the top of the lower container and an area surrounding the inlet of an "elongated, vertically disposed conduit" (passageway 4) which extends between the upper and the lower containers.

However nowhere does this application teach or suggest the provision of a mixture containing a transport gas and solid particles of an alloying ingredient, which mixture is directed into the shroud and into the interior of the descending stream of molten steel within the shroud at a stream location below the lower end of the conduit and above the lower end of the shroud.  For instance the alloying ingredient in the embodiment of Fig. 8 is in the form of a wire rod which is added to the molten steel when it is collected in the lower container, and not as it descends through the shroud.  In any case the use of a shroud with this embodiment is not specifically described or implied.

BHP Information Booklet

This booklet briefly describes a teeming operation in which molten steel is poured through a "conduit" (nozzle) in the bottom of an "upper container" (ladle) into a number of "lower containers" (ingot moulds) in turn.  No mention is made in the booklet of providing a shroud, and directing a mixture of a transport gas and solid particles of an alloying ingredient into the shroud, in the manner specified by the claimed invention.  This is regardless of whether I accept Mr Webster's assertion that the conventional procedure discussed within the introductory portion of AU 80905/82, in which shots of lead or lead alloy are injected into the molten steel, is representative of the known practice of adding solid alloying ingredients during the teeming operation. 

I therefore consider that the claimed invention differs from the prior art as established by the evidence in matters which clearly make a substantial contribution to its performance, so that the differences amount to more than mere workshop variations or mechanical equivalents.  As a result the prior art in question would not constitute an infringement of the claimed invention and the reverse infringement test is not satisfied.  Furthermore, it is well to remember here that it is not permissible in cases of lack of novelty to make a pattern or mosaic of or to read together discrete items of prior art in order to arrive at a combination patent (Nicaro Holdings v Martin Engineering (supra)).

Section 40

Mr Munt submitted that the independent claims went beyond the invention disclosed by the body of the specification since they omit the feature of creating a region of low pressure within the shroud.  Ms Slater responded by drawing my attention to the broad disclosure of the invention on pages 2 and 3 in which the creation of this low pressure region is said to merely relate to a preferred feature of the invention, and thus is not essential to it.

I also note in this respect from the disclosure at page 7, lines 7 to 11, that at least one of the problems addressed by the invention is solved simply by enclosing the conduit and the descending stream of molten metal within a shroud having inside walls laterally spaced from the conduit and the descending stream.  As a consequence, I consider that the paragraph commencing at line 16 of page 3 should not be taken to mean that the creation of a low pressure region within the shroud is essential to the performance of the invention.  For similar reasons, regulating the pressure in the low pressure region to control the rise of the molten metal does not in my view constitute an essential feature of the invention.   

However it seems to me from the final paragraph on page 6 that the creation within the shroud of a low pressure region by the descending stream is an inevitable consequence of the greater cross-sectional area of the interior of the shroud relative to that of the interior of the conduit and the descending stream.  In that event it could perhaps be argued on behalf of Inland that the feature of a low pressure region within the shroud is a feature inherent to independent claims 1 and 27.  This would of course create an ambiguity in the statement of claims due to the specific reference in claim 2 to the low pressure region.  On the other hand, the passage which bridges pages 2 and 3 appears to be suggesting that the creation of a low pressure region within the shroud is dependent upon the flow of the molten metal stream descending from the lower end of the conduit into the shroud which, in turn, suggests that the flow of molten metal could be regulated so as not to create a low pressure region within the shroud.

In view of the foregoing, I conclude that the specification does not fully describe the invention as regards the creation of the low pressure region.

Finally, I observe that although the broad disclosure on page 2 states that the shroud and the conduit are both composed of refractory material, and that the lower end of the shroud extends below the top of the bath of molten metal in the lower container, I am satisfied from the overall disclosure that these features are not critical to the invention.  Thus in my view the omission of these features from the independent claims does not give rise to an objection under sec 40. 

CONCLUSION

I have found that the opposition succeeds on the ground of non-compliance with sec 40, and I allow Inland 60 days from the date of this decision to propose amendments accordingly.

In accordance with the general principle that costs follow the event, I award costs against Inland.

O.L.Haggar
Delegate of the Commissioner of Patents

Patent attorneys for the applicant  :  Shelston Waters,

Sydney

Patent attorneys for the opponent   :  Griffith Hack & Co,

Melbourne