Ex Parte Grass

Patent Trial and Appeal BoardDec 16, 2014

12522378 (P.T.A.B. Dec. 16, 2014)

UNITED STATES PATENT AND TRADEMARK OFFICE ________________ BEFORE THE PATENT TRIAL AND APPEAL BOARD ________________ Ex parte HELMUT GRASS ________________ Appeal 2013-002935 Application 12/522,378 Technology Center 1700 ________________ Before BRADLEY R. GARRIS, TERRY J. OWENS, and GEORGE C. BEST, Administrative Patent Judges. OWENS, Administrative Patent Judge. DECISION ON APPEAL STATEMENT OF THE CASE The Appellant appeals under 35 U.S.C. § 134(a) from the Examiner’s rejection of claims 1–17 and 19–24. We have jurisdiction under 35 U.S.C. § 6(b). The Invention The Appellant claims a process for making hydrogen fluoride and calcium sulfate by reacting calcium fluoride with sulfuric acid. Claim 1 is illustrative: 1. A process for the preparation of HF and calcium sulfate wherein essentially dry calcium fluoride is reacted in the form of a suspension with essentially water free sulfuric acid in a reactor, wherein the solids content in the suspension is equal to or lower than 25 % by weight, wherein the calcium fluoride is Appeal 2013-002935 Application 12/522,378 2 comprised in a starting material which comprises basic calcium salts as impurities which react exothermically with the sulfuric acid and thus generate heat, and wherein the starting material contains said basic calcium salts in an amount equal to or lower than 25% by weight. The References Eipeltauer US 3,825,655 July 23, 1974 Salem US 4,741,741 May 3, 1988 Bhatt US 6,423,290 B1 July 23, 2002 The Rejection Claims 1–17 and 19–24 stand rejected under 35 U.S.C. § 103 over Eipeltauer in view of Salem and Bhatt. OPINION We reverse the rejection. We need address only the independent claims, i.e., claims 1 and 24. Those claims require that “calcium fluoride is comprised in a starting material which comprises basic calcium salts as impurities.”1 Eipeltauer discloses “a process for the production of hydrogen fluoride and metal sulfates by the reaction of metal fluorides, in particular 1 The Appellant states that “heat is supplied by the reaction between sulfuric acid and additives or, preferably, impurities contained in the starting material. For example, basic calcium salts, e.g., calcium oxide, calcium hydroxide or calcium carbonate might be added to calcium fluoride, as described above. Preferably, basic calcium salts are contained in the starting material as impurities. Such impurities are comprised in calcium fluoride containing residues originating from waste water or waste gas purification processes intended to remove HF, fluorides or HF precursors, as was explained in detail above. That is one of the reasons why such residues are preferred starting material” (Spec. 4:5–14). Appeal 2013-002935 Application 12/522,378 3 calcium fluoride, with an excess of sulfuric acid” (col. 1, ll. 44–47) wherein to provide heat, “substances which have highly exothermic reactions with H2SO4 or SO3 which result in the formation of substances which are inert with respect to the reaction products, can be introduced, for example together with the fluorides or at any other stage of the process” (col. 5, ll. 21–25). “Alkali or alkaline earth metal oxides or hydroxides e.g. NaOH, calcium hydroxide, and the like, may be added. Calcium oxide is a preferred additive” (col. 5, ll. 50–52). Salem discloses “a process for beneficiating coal or other solid carbonaceous matter comprising the steps of: (i) contacting particulate coal or other solid carbonaceous matter with hydrofluoric acid; (ii) mixing the mineral-depleted coal or other solid carbonaceous matter resulting from step (i) with an ammonium chloride solution, preferably aqueous ammonium chloride; and (iii) recovering the resultant beneficiated coal or other solid carbonaceous matter” (col. 3, ll. 47–56). The hydrofluoric acid can be recovered by treating an aqueous acid solution containing dissolved inorganic matter, such as fluorosilicic acid, with an aqueous calcium hydroxide solution to produce calcium fluoride and silica (which is separated from the calcium fluoride by simple centrifugation) and reacting the calcium fluoride with sulfuric acid to produce calcium sulfate and hydrogen fluoride (col. 5, ll. 21–54). Bhatt reacts hydrofluoric acid in an etching process waste stream with a base, preferably calcium hydroxide, to form insoluble calcium fluoride and water, and states that “it might be desirable to include an excess of about 10% or more of the base” (col. 3, ll. 1–4, 16–32). Appeal 2013-002935 Application 12/522,378 4 The Examiner argues (Ans. 7): The calcium fluoride obtained in Salem ‘741 would contain some residual unreacted calcium hydroxide since it is conventional in the art to add one reactant in excess to ensure that the reaction is carried to completion with respect to the other reactant. In this case, calcium hydroxide is expediently used in excess to ensure that all the HF in the solution would be recovered in the form of CaF2. Also optionally, Bhatt ‘290 can be applied to teach that when calcium hydroxide is used to react with the hydrofluoric acid in a waste solution to form insoluble calcium fluoride and water, it is desirable to include an excess of about 10% or more of the calcium hydroxide (note column 3, lines 24-32). . . . It would have been obvious to one of ordinary skill in the art at the time the invention was made to use the calcium fluoride by-product, as suggested by Salem ‘741, as the starting material for the process of Eipeltauer ‘655 because it contains both the calcium fluoride and the additive as required in Eipeltauer ‘655 and because by using the calcium by-product as suggested by Salem ‘741, the reactant cost can be minimized. The Examiner argues, in reliance upon the CRC Handbook of Chemistry and Physics, that Salem’s and Bhatt’s calcium hydroxide is a solid and, therefore, is in suspension form (Ans. 15–16). The Examiner’s argument is deficient in that the Examiner has not established that even if excess calcium hydroxide were used to produce Salem’s calcium fluoride and the calcium hydroxide were in solid form, the excess calcium hydroxide would not be removed with the silica during the centrifugation but, rather, would be present as an impurity in the calcium fluoride (see Reply Br. 10–11). Appeal 2013-002935 Application 12/522,378 5 Thus, the Examiner has not set forth a factual basis which is sufficient to support a prima facie case of obviousness of the Appellants’ claimed invention. See In re Warner, 379 F.2d 1011, 1017 (CCPA 1967) (“A rejection based on section 103 clearly must rest on a factual basis, and these facts must be interpreted without hindsight reconstruction of the invention from the prior art”). Accordingly, we reverse the rejection.2 DECISION/ORDER The rejection of claims 1–17 and 19–24 under 35 U.S.C. § 103 over Eipeltauer in view of Salem and Bhatt is reversed. It is ordered that the Examiner’s decision is reversed. REVERSED lp 2 The Appellant and the Examiner may wish to address, in any further prosecution, whether Eipeltauer would have rendered prima facie obvious, to one of ordinary skill in the art, acid-grade fluorspar as the calcium fluoride source and, if so, whether the fluorspar would contain calcium carbonate as an impurity. See Ullmann’s Encyclopedia of Industrial Chemistry §§ 1.3, 1.3.1 (Wiley 2000) (disclosing that acid-grade fluorspar contains 1% max calcium carbonate).