OUTOKUMPU Oy v Asturiana De Zinc S.A

[1983] APO 26

In the Matter of the Patents Act 1952

‑ and ‑

In the Matter of Application No. 495156 in the Name of OUTOKUMPU OY

‑ and ‑

In the Matter of Opposition thereto by ASTURIANA DE ZINC S.A.

DECISION OF A SUPERVISING EXAMINER OF PATENTS:
BACKGROUND
         Acceptance of this application was advertised on 17 August, 1978.  Notice of opposition to the grant of a patent was lodged by Asturiana de Zinc S.A. on 16 February, 1979 after the granting of an extension of time in which to do so.   Mr. D.C. Carter, patent attorney, of Cowie, Thomson & Carter represented the applicant and Mr. J. Terry, patent attorney, of Griffith, Hassel & Frazer, represented the opponent.
         The matter was heard in Canberra on 27, 28 and 29 July, 1982 in the form of a cross‑opposition as Outokumpu had opposed Asturiana's patent application 483655 and my finding in relation to the present opposition is directly related to my finding in the opposition to Asturiana's application. Locus standi of the opponent was not an issue.
         Patent application 495156 was lodged on 11 February, 1974 as a Convention application, based on an application for protection, No. 410/73 made in Finland on 12 February, 1973.   Mr. Terry, at the Hearing, indicated that Asturiana does not contest, for the purposes of these proceedings the

allocation, of the Convention date as the priority date of the present claims : I am satisfied that the present claims can be allocated a priority date of 12 February, 1973.
Outokumpu's Patent Application 495156
         The specification of Outokumpu's Application No. 495156 is concerned with an hydrometallurgical process for the treatment of a raw material containing an oxide and a ferrite of at least one of the non‑ferrous metals zinc, copper and cadmium.   The process disclosed involves the neutral leaching of raw material, in particular calcine, to dissolve the oxide while leaving undissolved ferrite.   This ferrite containing residue is then admixed with additional H2SO4 or Fe2(SO4)3 bearing solution containing enough H2SO4 or Fe2(SO4)3 respectively to satisfy a given chemical reaction thereby causing the non‑ferrous metals to dissolve whilst simultaneously precipitating iron as jarosite.   The process is carried out at atmospheric pressure and at a temperature of from 80` to 105`C.   In example 1 of Outokumpu zinc ferrite bearing material is mixed with spent electrolyte: the temperature of the conversion stage is kept at 95`C and the H2SO4 content adjusted by acid additions to between 22‑25 g/l to yield a solution containing 22.0 g/l H2SO4, 5.4 g/l Fe and 5 g/l NH4+.
         The Outokumpu specification ends with 11 claims, claims 1 and 7 being the sole independent claims.   For the purposes of this decision it suffices only to refer to claim 1.   Claim 1 of Outokumpu reads:

"A hydrometallurgical process for the treatment of a raw material containing an oxide and a ferrite of at least one of the non‑ferrous metals zinc, copper and cadmium, comprising neutral leaching said raw material with a sulfuric acid bearing solution to dissolve said oxide while leaving said ferrite substantially undissolved separating a residue containing said ferrite, admixing additional sulfuric acid bearing solution and in the presence of ions selected from the group consisting of sodium potassium and ammonium ions with said residue at atmospheric pressure and at a temperature of from about 80` to 105`C, said additional sulfuric acid bearing solution containing sufficient sulfuric acid to satisfy the reaction:

3 MeO.Fe2O3+(7‑x)H2SO4 + xA2SO4 + (2 ‑ 2x)    H2O

2Ax(H3O)1‑x [Fe3SO4)2(OH)6] +3 MeSO4

where Me is zinc, copper, or cadmium and A is sodium, potassium or ammonium, and x has a positive value not exceeding 1, and thereby causing said non‑ferrous metals present to dissolve as sulfates while simultaneously precipitating iron as jarosite, and separating and recycling a solution containing said dissolved non‑ferrous metals to said neutral leaching."

ANTICIPATION AND PRIOR CLAIMING
         The opponent argued that there was a prior claiming situation existing between the claims of the present specification and those of Asturiana's application 483655.
         The prior claiming matter turned on the allocation of priority dates of the respective claims.   As I have found in the opposition to 483655 that the claims of the Asturiana specification are to be treated as having a priority date later than that of the present claims, I find that the opponent has failed to establish prior claiming of any of the claims of the present specification.
         A number of documents relating to the grounds of prior publication and lack of novelty are exhibited to the declaration by Mr. Willis in the corresponding opposition to Asturiana's 483655.   I consider that these documents are also relevant to a consideration of whether the invention defined by the present claims is prior published and not novel.   I am of the opinion that these documents neither prior publish nor establish want of novelty of the invention of the present claims.   My reasons for arriving at such a finding are those set out in the corresponding opposition : I repeat them here for the sake of convenience.
Australian Patent Specification 401724
         Patent specification 401724 by Electrolytic Zinc Company of Austral‑
asia Limited (which I shall refer to as EZ) was published on 14 September, 1967.   This patent specification entitled "Treatment of Zinc Plant Residues" indicates in its opening paragraph that the invention relates to the hydrometallurgical extraction of zinc plant residue.   It sets out as an object of the invention, the efficient extraction of zinc present as zinc ferrite in zinc plant residue whilst minimising the iron content of the resulting solution.   A statement of invention appears at page 5 and is similar to claim 1 apart from the substitution of the expression "heating the leach solution to an elevated temperature" by the expression "heating the leach solution to a temperature above 60`C".   This statement reads:

"The invention accordingly provides a method of treating zinc plant residue containing zinc ferrite which comprises the steps of leaching the residue in a solution containing between 15 and 300 gms per litre of sulphuric acid at a temperature between 60`C and the boiling point of the solution at atmospheric pressure, heating the leach solution to an elevated temperature in the presence of sodium, potassium and/or ammonium ions so that ferric iron is precipitated as an insoluble double sulphate of the jarosite type, and separating the purified leach solution from the precipitated iron compound."

The invention of EZ therefore clearly relates to a "two stage" zinc recovery process where solution of ferrite and precipitation of ferric ion are carried out in separate steps.
         As can be seen from the statement of invention, the precipitation step is based on a "jarosite process".   EZ discusses the factors involved in this process throughout its description, particularly at pages 6 and 7.   The statement of invention indicates that the precipitation step is carried out at an "elevated temperature" which, according to claim 1, is "above 60`C".   It is interesting to note that prior to the statement of invention at page 5 the specification at page 4 states:

"It has also been found that the resulting leach solution preferably after the separation of the undissolved residual solids, can be substantially purified of dissolved iron by adding certain reagents, and heating the solution to a temperature between 140` and 240`C.   Under these conditions iron can be precipitated from the solution to an extent that the final solution can contain less than 3 grms of iron per litre."   (emphasis added).

Again, at page 8 EZ states:

"... heating the leach solution to an elevated temperature, and preferably to a temperature above the boiling point of the solution at atmospheric pressure."

And at page 13:

"The leach solution, preferably after separation from undissolved solids, is then passed to the precipitation stage where the necessary reagent or reagents are added and the solution is heated in a pressure vessel, such as an autoclave, to a temperature preferably in the range 140 to 240`C."   (emphasis added).

and at page 15:

"Provided the precipitation of double sulphate is conducted in the range 160‑200`C addition of reagents to give a level of 0.5 to 3.0, but preferably 1.25 to 1.5 times the stoichiometric requirements ... is sufficient to lower the final iron concentration."   (emphasis added).

The examples of EZ illustrate the precipitation stage as one carried out in an autoclave at temperatures above the boiling point of the solution at atmospheric pressure.
         It is the opponent's contention that where the specification, at page 8, states:

"During the precipitation step the amount of free H2SO4 present is preferably between 20 and 75 gms per litre."

it refers to the broad range of temperature specified in claim 1 of EZ, that is, above 60`C.   According to Mr. Willis in paragraph 6 of his second declaration, the above quoted passage "discloses that precipitation occurs at an elevated temperature which is below the boiling point" at an acid level between 20 and 75 grms H2SO4, that is, EZ discloses that jarosite precipitation can occur at acid levels which are high compared to 5 grms per litre at temperatures below the boiling point at atmospheric pressure.
         This particular assertion is contested by Professor Lawson who maintains that the acid range of between 20 and 75 grms H2SO4 must relate to temperatures above the boiling point, otherwise there is an inconsistency between the statement at page 12 of EZ where it is stated that an acid level between 15 and 30 grms per litre free H2SO4 is sufficient to prevent hydrolysis and precipitation in the leaching step and the above statement made in relation to the precipitation step where a high acid range of between 20 and 75 Grms per litre is recommended.
         Having considered the submissions of both parties I conclude that the reference to 20 and 75 grms per litre free H2SO4 in the precipitation step relates to the preferred precipitation temperature of greater than the boiling point of the solution at atmospheric pressure.   Thus I do not consider that EZ contains clear directions indicating that precipitation can be carried out at high acid levels.   This conclusion is based first on the above quoted passages of EZ emphasising the preferred temperature range as one above the boiling point (particularly the statement at page 4) and second, the statement at page 10 which says:

"Consequently where a high acid concentration is employed in the leaching stage the excess may be partially neutralised by the addition of zinc oxide calcine or other suitable neutralising agent, prior to the iron precipitation stage."

which appears to me to direct the reader away from carrying the precipitation reaction at high acid levels.
         Also, in the paragraph bridging pages 14 and 15 it is said:

"At fixed additive concentration the extent of precipitation is increased by an increase in temperature and by a decrease in free acid level in the solution.  Thus the extent of precipitation may be increased by the addition of zinc oxide calcine, or other suitable neutralising agent to react with and neutralise free acid, either remaining in solution after the leaching stage, or liberated during the precipitation stage.  The addition of excessive amounts of zinc oxide calcine should be avoided however, because of the attendant loss of some zinc in the undissolved residual solids such as in zinc sulphide originally present in the calcine."

I interpret this paragraph as saying that there are two ways of carrying out the precipitation, increasing the temperature (as is done in the preferred process at above the boiling point), or neutralising excess acid by the addition of a neutralising agent with its attendant loss of zinc.
         I note the comment made by Dr. Jussi Kalevi Rastas on behalf of the opponent at page 22 of his declaration:

"Haig and Pickering ‑ If on the other hand a neutralising agent is not used in connection with the precipitation, the precipitation must be performed, as advised by Pickering under autoclave conditions within the temperature range 140‑240`C."

and at page 25 of his declaration:

"If the process is performed according to Haig and Pickering, the zinc ferrite process connected with the neutral leaching of calcine has two stages.   One of these stages is, however, performed in an autoclave ..."

Dr. Rastas cannot be regarded as a "man skilled in the art" in Australia and I treat his assertions with caution, however it is interesting to note his understanding of EZ.
         I now turn to the leaching step of EZ which appears to be the step most relied upon by the opponent as it is here that the possibility of precipitation is discussed in a stage where dissolution of ferrite is also carried out.   The two paragraphs bridging pages 9 and 10 mention the possibility of hydrolysis and precipitation of iron during the leaching stage:

"It is found that about a 10% excess of sulphuric acid, above the stoichiometric quantity required to dissolve the zinc ferrite content of the residue, according to the following equation, is a satisfactory acid concentration

ZnFe2O4 + 4H2SO4 ‑‑ ZnSO4 + Fe2(SO4)3 + 4H20.

This amount of excess acid is sufficient to maintain a fast rate of solution of the ferrite.   It also enables sufficient free, or uncombined, sulphuric acid to remain in solution to stabilize the ferric iron, and thus prevent hydrolysis and precipitation of iron in the leaching stage.

The amount of free acid required to stabilize the ferric iron in solution increases with an increase in the leaching temperature, in the concentration of ferric sulphate, and in the concentration of any of the precipitants, potassium, sodium, or ammonium ions which may already be in solution.Although higher acid concentrations can be employed with a consequent increase in the rate of zinc ferrite dissolution, in order to achieve the maximum seaparation of iron in the precipitation stage too much excess acid should preferably be avoided."

The hydrolysis and precipitation of iron is again referred to on page 10:

"Although any hydrolysis and precipitation of iron during the leaching stage does not seriously affect the rate or extent of zinc extraction from zinc ferrite, it would contaminate the undissolved residual solids.   In the applicant's case the undissolved residual solids are a valuable source of metals such as lead and silver, and any unnecessary contamination is therefore undesirable.   In a plant treating residue which does not contain any valuable metals other than zinc re‑precipitation of part of the iron from solution during the leaching stage would not be a serious matter.

The nature of the hydrolysis and precipitation must first be ascertained; that is, whether it is the precipitation of double sulphate that is being referred to or the precipitation of goethite.   Mr. Willis, in paragraph 4 of his evidence‑in‑support, reads the reference to hydrolysis and precipitation as relating to "Fe(OH)3" (geothite) formation, however Professor Lawson in paragraph 13 of his declaration indicates that there is no possibility of ferric hydroxide formation at such high acidity and that the hydrolysis to be prevented by excess acid is the precipitation of jarosite.   Mr. Willis agrees in paragraph 8 of his evidence‑in‑reply that the relevant paragraphs of EZ refer to prevention of jarosite precipitation during leaching although he maintains that high free acid will prevent both ferric hydroxide and jarosite hydrolysis.
         EZ at page 6 indicates that:

"if ammonia is used as a base to precipitate ferric iron from a leach solution containing ferric sulphate and sulphuric acid, sufficient ammonia must be added to neutralise the free acidity of the solution and to precipitate ferric ion".  

On page 7 however, it says:

"Unlike the reaction involving the precipitation of ferric oxide, the precipitation of the ammonia‑jarosite occurs from acid solution."

and

"There is the additional difference also that free acidity in solution must first be neutralised if ferric iron is to be precipitated as the hydroxide whereas jarosites are precipitated from solutions containing free acid".  

It thus appears that both reactions can occur when there is free acidity in the solution, however, the nature of precipitant depends on the degree of acidity. In paragraph 10 of his declaration Professor Lawson states that, in context, the ferric hydroxide will not precipitate until the acid level has been reduced and pH increased to above about 3.5.   I read EZ as saying that the factor of 10% excess of sulphuric acid above the stoichiometric quantity required to dissolve the zinc ferrite is intended not only to prevent precipitation of ferric hydroxide but also to prevent the precipitation of basic sulphate, the possibility of which the specification acknowledges when it refers to the dependency of the stability of the ferric ion solution on, inter alia, the concentration of any of the precipitants, potassium, sodium, or ammonium ions which may already be in solution.   The fact that these precipitants may be already in the leach solution is indicated at page 16 where it is stated that the neutral ions may be directly added into the autoclave in which the precipitation step occurs or added to the leach solution prior to entry into the autoclave or may be added or present in solution in the leaching stage.
         I return to the above‑quoted passage relating to the undesirability of contamination of residual residues by hydrolysis and precipitation of iron during the leaching stage.   I construe this passage as indicating that any re‑precipitation of iron is undesirable irrespective of the form of the precipitant, that is, the precipitation of iron in any form should be avoided if valuable material recovery is to be undertaken.   I thus interpret the paragraph as not solely concerned with jarosite precipitation although it certainly forsees this possibility and counsels its prevention ‑ the excess acid level is pitched at the higher value to ensure that the ferric hydroxide precipitation is certainly prevented and that any possible jarosite precipitation is also prevented.
         The opponent's contention in relation to EZ is set out in paragraph 4 of Mr. Willis' evidence in support.

"... Thus Australian Patent 401724 discloses a leaching solution operating at high temperature with high acidity which fall within the ranges disclosed in 483655.   Further it discloses the possible presence of complexing ions and that precipitation is known to occur.   The reason why they found this undesirable is given.   Page 14, lines 23 to 31 clearly discloses the reason why it is normal to use low acidity levels is that the precipitation reaction is inhibited by the presence of too much free acid.   It is for this reason since oxide is added.   Thus it is clear that it was known prior to October 20th, 1972, which is the priority date of 483655 that simultaneous dissolution of zinc ferrite and precipitation of Jarosite occurred due to the presence of complexing ions in the leaching solution.   The ranges of temperature and acidity being within that of 483655.   However, such was discouraged purely from the point of view of contamination of valuable metal which may also be present as well as the inhibition of fast precipitation under the influence of excess acidity."

I am not so sure that EZ does indeed teach simultaneous dissolution of zinc ferrite and precipitation of jarosite.
         The broad statement of invention appearing at page 8 and definition of the invention in claim 1 of EZ indicate that leaching of the residue is carried out in a solution containing between 15 and 300 gms per litre sulphuric acid ‑ a very broad range of acid level.   A more detailed indication of acid levels appears at page 8 (already quoted) where a level of 10% excess sulphuric acid above the stoichiometric amount required to dissolve the ferrite is recommended, this level enabling "sufficient free, or uncombined, sulphuric to remain in solution to stabilise the ferric iron [sic] ...".   At page 11 the range of greater than 15 grms and less than 300 grms sulphuric acid is again repeated, then reference is made to fortification of spent electrolyte to a level of 140 grms sulphuric acid.   The specification continues:

"With this degree of fortification and with a solids loading of about 110 grms of residue per litre, to give a solution containing preferably abour 25 to 35 grms of iron per litre, the concentration of free sulphuric acid in the solution leaving the leaching stage is between 15 and 30 grms per litre.   This level is just sufficient to prevent hydrolysis of iron during the leaching stage under preferred conditions" (my emphasis).  

This part of the specification thus teaches a leaching process in which the initial H2SO4 value is high (140 gms per litre) which acid level gradually decreases as H2SO4 reacts with the ferrite residue to a level between 15 and 30 grms per litre.   The examples illustrate a similar situation in relation to acid levels.   In this context I read EZ as instructing the reader of the possibility of precipitation and hydrolysis of ferric ion towards the end of the leaching step, that is, at a time when much of the original sulphuric acid originally present has been consumed by reaction with ferrite to produce iron sulphate and zinc sulphate and the acidity of the solution is dependent on the residual H2SO4 amount.   If the proper allowance has not been made then the acidity will drop to a level in which jarosite may precipitate, or indeed, if the acidity level drops to a low enough level even goethite may precipitate.
         Professor Lawson in paragraph 14 of his declaration states:

"Thus the overall teaching of this passage [page 12 lines 6 to 8] of the EZ patent is to acknowledge that hydrolysis and precipitation of iron could occur during the leaching stage but this can be avoided by operating a leaching condition of for example 95`C, free acid in the range 15 to 30 grams per litre and for a time of 6 hours."

As can be seen from my previous comments, I do not agree with Professor Lawson's conclusion on this point, I consider that EZ teaches the leaching stage to be carried out with an excess of H2SO4 over the stoichio‑
metric requirement such that the concentration of free sulphuric acid of the solution leaving, (i.e. towards the end of the process) is between 15 and 30 grms per litre ‑ such a level of acid being just sufficient to prevent hydrolysis and precipitation.
         Whilst emphasising that I have not relied on the assertions of Dr. Rastas (an obvious foreign technical expert in the field of the invention) in reaching my conclusions on this point, it is again interesting to note his comments.  At pages 22 and 23 of his declaration he states:

"Among professions who have used the process it is well known that when the acid contration decreases too much during the final stage of the leach some iron may precipitate as jarosite.   Pickering also refers to this.   This partial precipitation of iron at the ferrite leaching stage has been found to be a disadvantageous phenomenon since the precipitated jarosite dilutes the leach residue (Haig & Pickering).   In order to eliminate this drawback Haig & Pickering add an excess of 10 per cent sulphuric acid at the leaching stage. ... whereby the sulphuric acid at the end of the leaching stage is 15‑30 g/l, which according to Haig & Pickering prevents the hydrolysis of iron under leaching conditions."

It follows from my interpretation of the leaching of EZ that any possible hydrolysis and precipitation of iron during the leaching stage occurs at the latter stages of leaching where most of the ferrite has been dissolved.  I cannot regard this disclosure as a clear teaching of the possibility of the simultaneous ferrite dissolution, iron hydrolysis and precipitation of Asturiana claim 1.
         EZ is primarily concerned with a two stage process in which leaching and precipitation are carried out in separate steps.   The fact alone that EZ teaches the need for two separate steps, leads the reader away from a consider‑
ation of a single stage process wherein the reactions occur simultaneously.   Also, the reference to hydrolysis and precipitation in EZ relates to the side issue of preventing contamination of any residue from the leaching step where further valuable metal recovery is to be undertaken ‑ the references certainly do not concentrate on the possibility of the phenomenon having any use in a process of zinc recovery.   Further the reference to hydrolysis and precipitation, in the context of EZ description and examples relate to the latter stages of the leaching operation where dissolution of ferrite has mostly occurred.   In this context it is difficult to see how the reader of EZ would comprehend the possibility of a simultaneous solution and precipitation let alone the possibility of it being an effective means for zinc recovery in a single stage.   Consequently there is no publication or lack of novelty involved with respect to this citation.
German Patent 1948411
         This specification was available in the Patent Office Library on 12 October, 1971.   Mr. Willis indicated in paragraph 10 of his second declaration that he relies on this citation for its disclosure of the use of manganese dioxide as an oxidising agent in the jarosite process.   It does not teach the simultaneous process of the present claims.
"Erzmetall", Vol. 23 (1970), No. 11, p.532‑539
         The evidence shows that the "Erzmetall" article in question was available to the public at Melbourne University Engineering Library on 14 January, 1971, that is, before the earliest priority date of the present application.   The article is first referred to by Mr. Willis in paragraph 6 of his declaration in support.   Mr. Willis places particular reliance on figure 4 of the "Erzmetall" article which shows the precipitation of iron following the dissolution of zinc ferrite (total dissolved iron concentration [g/l] vs, time [hours]).   Mr. Willis contends that at the peak of Figure 4 (the graph of total iron) the rate of dissolution of iron must equal the precipitation rate, i.e. simultaneous solution of ferrite and precipitation of basic sulphate.   Much technical argument has been presented by Mr. Willis and Professor Lawson concerning the disclosure of figure 4, however, I do not consider that the "Erzmetall" article discloses the simultaneous process of Asturiana claim 1.  There is no discussion in the "Erzmetall" article of the possibility of simultaneous solution and precipitation and I consider Mr. Willis has only derived information from figure 4 with ex‑post facto knowledge.   The article itself does not refer to the possibility of zinc recovery using the simultaneous process nor would the disclosure lead the reader to consider that possibility.
Norwegian Patent 123248
          Norwegian patent specification 123248 has been available in the Australian Patent Office since 3 May, 1972.   This citation does not disclose the simultaneous process of the present claims nor does it lead the skilled addressee in that direction.  Consequently it neither prior publishes nor renders not novel the invention of the present claims.
SECTION 40
         Mr. Terry asserted that the present claims were not fairly based because of Dr. Rastus' assertions as to what he considers the essence of his invention differs from what has been defined in the present claims.   However, it is well established that questions of construction are to be decided by the Commissioner or his delegate.   On a reading of the specification as a whole I am not satisfied that the opponent has established that the claims are not fairly based.   Accordingly I find that the opponent has failed to establish its ground of non‑compliance with section 40.
OBVIOUSNESS
         I do not believe that the evidence establishes that a non‑inventive worker would as a matter of mere routine and without benefit of hindsight, carry out a process involving the simultaneous dissolution of ferrite and precipitation of basic iron sulphate.   Consequently I find that the opponent's obviousness objection fails.
CONCLUSION
         I find that the opponent has failed to establish any of the grounds of opposition upon which it has relied.   I am also satisfied that there is no lawful ground of objection to the application and complete specification.  Consequently I direct that the application and complete specification may proceed to sealing, subject to any appeal.   I award costs against the opponent.

(J.L. ROVETA)