T 0735/11 15-01-2014

Reasons for the Decision

1. Amendments (Article 123 (2), (3) EPC)

1.1 Main request

Claim 1 is based on a combination of features from claims 1 and 3 and the description, paragraph [0045], first sentence, as originally filed.

The board sees no violation of Article 123(2) EPC in combining said features into a new independent method claim, for the following reasons.

1.2 Firstly, claim 3 as originally filed was dependent on claim 1, so that its features, in particular the feature relating to the addition of water in an amount of 5 to 15 weight-%, are disclosed in combination with those of claim 1.

Secondly, the description, paragraph [0045], clearly refers to the invention as such ("According to preferred embodiment of the invention..."). The subsequent preferred feature, relating to mixing and granulation using the same apparatus, is thus understood to be combinable not only with the embodiment defined in claim 1, but also with further preferred embodiments containing features of the claims which depend on claim 1.

Claim 13 is fairly based on original claims 14 and the description, paragraph [0045], first sentence, as originally filed. For the allowability of the combination of features similar arguments as above apply.

1.3 Auxiliary request

Claim 13: The new feature relating to the "means for dispatching the steam from the high shear mixing apparatus" is based on the original disclosure of paragraph [46] of the description.

1.4 The requirements of Article 123(2) and (3) EPC are thus met.

2. Clarity of the claims

The method of claim 1 requires "adding water to the reaction mixture in amount of 5 - 15 weight-%". This feature was already present in granted claim 3 which depended on claim 1. Therefore, any alleged lack of clarity in connection with this particular feature must have affected the claims as granted. Adding still another claim feature, relating to the use of the same apparatus for mixing and granulation, apparently does not influence the alleged clarity problem concerning the amount of water added.

However, objections under Article 84 EPC do not fall under the grounds of opposition (Article 100 EPC) and thus cannot be dealt with in opposition or subsequent appeal proceedings.

The respondent also argued that the process step of granulation had no antecedent in the pre-characterising clause of claim 1, giving rise to a lack of clarity.

However, claim 1 literally relates to a a method of producing a granular material which clearly implies a granulation step.

3. Sufficiency of disclosure (Article 83 EPC)

3.1 The respondent's objection concerns the granulating step which was mentioned neither in claim 1 nor in the examples. Nevertheless, in examples 1 to 3 a granular end product was obtained, whereas the final product in accordance with examples 4 to 6 had a powdery consistency. The patent did not disclose whether in the examples different types of mixing apparatus were used. Therefore, the claimed invention was not disclosed sufficiently clearly and completely to be carried out by the skilled person.

Furthermore, according to the respondent, as none of the examples 1 to 6 comprised a step of water addition, none of them fell under the scope of claims 1 or 13. In the respondent's view, the invention was not supported by working examples and could not be re-worked by the skilled person.

3.2 Generally, for an objection of insufficiency of disclosure to succeed, it is necessary to identify a gap in information and/or lack of guidance which cannot be compensated for by general knowledge.

3.3 In the present case, the board is convinced that granulation of the material can be carried out by the skilled person in spite of the lack of detailed information in the opposed patent. Granulation of a (moist) material is a process common in the art and suitable apparatuses are well known to the skilled person. This implies on the other hand that this particular claim feature cannot be considered as involving an inventive step.

Further explanations in this regard are not necessary, since the contested patent cannot be maintained for the reasons set out further below.

4. Novelty

4.1 D16 was cited as novelty-destroying for the subject matter of claim 1. The respondent's arguments were in particular that

- the amount of water added in accordance with the teaching of D16 (100 to 550 mole-%) overlapped with the amounts given in the patent in suit;

- granulation was carried out directly after the addition of water, without transfer into another vessel or apparatus; therefore, D16 could be considered to generally disclose mixing and granulation in the same apparatus.

4.2 The board cannot agree for the following reasons. Although D16 does not explicitly mention a step of transferring the reaction mixture from the mixing apparatus to a different apparatus for carrying out the granulation step, this fact cannot be construed as a positive disclosure of the claim feature according to which mixing and granulation shall take place in the same apparatus. On the contrary, D16 discloses on page 14, penultimate paragraph, and in claim 33 that granulation is preferably effected by processes such as mechanical shaping, spraying with air, spraying through a nozzle or by using a rotating disk or a cooling belt or drum. None of these apparatuses is apparently typically designed in such a way that a previous mixing step could be carried out in it.

Novelty of the subject-matter of claims 1 and 13 of the main request and of claim 1 of the auxiliary request is therefore accepted.

The dependent claims 2 to 12 and 14 are also novel by virtue of their dependency.

The requirements of Article 54 EPC are met.

5. Inventive step

5.1 The opposed patent is concerned with a method of producing a granular material having a high soluble iron(II) content from a crude precipitate comprising iron(II)sulphate monohydrate, and with a plant for producing such a granular material. The claimed method involves mixing and partially neutralising the crude precipitate with water and a neutralising agent while maintaining specified conditions of temperature and pH, and granulating the reaction mixture using a mixing/granulating apparatus.

5.2 D1 (cited in paragraph [0007] of the patent in suit) is considered to represent the closest prior art.

D1 reveals a method of making ferrous sulphate hydrate starting from a moist side product of the titanium pigment (TiO2) production comprising iron(II)sulphate monohydrate and sulfuric acid. The moisture content of the material is preferably approximately 10% (see page 2, lines 10 to 13, 19 to 21 and 29 to 34). This starting material is partially neutralised to a pH of 1.5 to 5 by mixing in cement as a CaO-containing material and optionally slag, fly ash or limestone (see claims 2 and 3). On a large scale, mixing may be carried out in a continuous concrete mixing plant (see example 1). Importantly, to avoid oxidation of Fe**(2+) and to retain the hydrate water, the reaction temperature must not exceed 120°C (see page 2, line 29 to page 3, line 12; paragraph bridging pages 4 and 5).

The product so obtained is non-dusting, has excellent handling and flow characteristics (page 3, lines 9 to 12). Although the product presumably consists of particles coarser than dust, it is not unambiguously disclosed as being granular. The product is useful for the reduction of chromium (VI) in the manufacture of cement (see page 1, first paragraph; example 3).

5.3 According to the patent in suit, the problem underlying the patent in suit is to provide a simple method for obtaining, from a crude precipitate comprising iron(II) sulfate monohydrate and sulfuric acid derived from titanium dioxide production, a granular material having a high soluble iron(II) content, with which method in a minimum of time a relatively homogenous material in granulate form can be produced without extensive pre-treatment of the used raw materials (see patent in suit, paragraphs [0010],[0011] and [0012]).

5.4 As a solution to this problem, the patent proposes a method in accordance with claim 1 of the main and auxiliary requests, characterised in that water is added to the reaction mixture in an amount of 5 to 15 weight?% and that mixing and granulation is carried out in the same apparatus.

5.5 As to the success of the solution, it is plausible that by the claimed method a granular product having a high soluble iron(II) content can be obtained. The board also considers that the claimed process is simplified insofar as the mixing and granulation takes place in the same apparatus.

The board is therefore satisfied that the problem as stated in the patent in suit has been successfully solved.

Hence, there is no need to reformulate the problem in the light of document D1.

5.6 The question to be answered now is whether the claimed solution was obvious in view of the prior art.

The board notes that the patent in suit does not place any particular restrictions on the type of apparatus used for the combined mixing/granulation. According to preferred embodiments, a high-shear mixer or a fluid-bed mixer (such as an R-type Eirich mixer or a Lödige mixer) is used; however, these are not mandatory in the claimed process. The board concludes that any suitable mixing/granulation apparatus known in the art may be successfully employed in the claimed method.

The respondent has pointed out that such combined apparatuses are known for instance from D11 (column 5, lines 28 to 32; Figure 1), D5, D7 and D8a. Particular attention was directed to D5, page 14, "Maschinen für Chargenbetrieb", disclosing Eirich batch mixers for simultaneous mixing, moistening, reacting, granulating and surface-drying. D8a (see page 2) discloses a continuous ploughshare mixer having optional mixer blades in the mixing drum for disintegration of agglomerates and the forming of a granulate.

Document D11 discloses in Figure 1 and column 6, lines 19 to 31 and 47 to 55, a combined mixer/reactor/granulator having inlets for sludge (9), inlets (7, 14) for solids such as CaO, and an inlet (15) for water, a mixing/granulating chamber (2) with rotating blades (4), an outlet (10) for the granulated product (11) and a steam exhaust (13).

In the board's view, the skilled person would employ the combined mixing/granulation apparatus disclosed in D11 in the method otherwise known from D1 to provide a simple method of making a granular product.

As regards the step of adding water to the reaction mixture, the board considers that it is a priori obvious to make sure that the mixture contains enough water - depending on the moisture content of the raw material - for the formation of granules. Adding water to the mixture is an obvious measure to adjust the water content if the initial amount in the starting product and reactants is insufficient for that purpose. The exact total water content necessary for granulation must be determined experimentally, for the opposed patent confines itself to explaining what is in the board's opinion common knowledge, namely that raw materials with high water content yield soft and irregular granules, whereas medium water content in the reaction mixture leads to effective formation of dry and hard granules (see paragraph [0034].

The amount to be added as specified in the claims (5 to 15 weight-%) is, in the board's view, neither selected purposefully nor particularly critical, because the initial moisture content of the crude precipitate (up to 10% according to D1) is not taken into account and the amount of water lost as steam during neutralisation (where the temperature rises to a maximum of 120°C) is not known a priori. Therefore, for determining the actual amount of water which must be added to obtain granules, the patent's teaching offers of little guidance.

According to an argument of the appellant, the fact that no water is added in the method of D1 would teach away from the method as now claimed. The board does not find this argument persuasive, because the aim in document D1 is to produce a powdery, non-dusting product with good flow characteristics (see page 3, lines 5 to 19). As no granulation takes place in D1, there is apparently no need to add water to the mixture. In contrast, in the claimed invention, it is obvious that the water content must be controlled and, if necessary, water must be added, for granulation to take place. On the importance of controlled water addition for the granulation process, see for instance D11, paragraphs [0021], [0022], [0035] and [0044].

The fact is that the basis for the amount of water (5 to 15%) to be added is not indicated in the claim. Therefore, it is not clear whether the claimed weight - percentages of water addition refer to the amount of initial material, to the mixture of materials or to the solids content of the mixture. This claim feature can only be taken as a hint to add water but it cannot be considered as involving an inventive step.

5.7 The subject-matter of claim 1 of the main request and of the identical claim 1 of the auxiliary request thus does not involve an inventive step (Article 56 EPC). Therefore, these requests must both fail.