Case: 22-1459 Document: 46 Page: 1 Filed: 03/10/2023

NOTE: This disposition is nonprecedential.

United States Court of Appeals for the Federal Circuit ______________________ CHEMCO SYSTEMS, L.P., Appellant v. RDP TECHNOLOGIES, INC., Appellee ______________________ 2022-1459 ______________________ Appeal from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. IPR2019- 01564. ______________________ Decided: March 10, 2023 ______________________ JENNIFER L. SWIZE, Jones Day, Washington, DC, for ap- pellant. Also represented by MARLEE HARTENSTEIN, MATTHEW JOHNSON, Pittsburgh, PA. THOMAS FISHER, Cozen O'Connor P.C., Washington, DC, for appellee. Also represented by KERI SCHAUBERT, New York, NY. ______________________ Case: 22-1459 Document: 46 Page: 2 Filed: 03/10/2023

2 CHEMCO SYSTEMS, L.P. v. RDP TECHNOLOGIES, INC.

Before MOORE, Chief Judge, PROST and STARK, Circuit Judges.

PROST, Circuit Judge.

Chemco Systems, L.P. (“Chemco”) petitioned for inter partes review of claims 1 and 2 of U.S. Patent No. 7,416,673 (“the ʼ673 patent”) owned by appellee RDP Technologies, Inc. In a final written decision, the Patent Trial and Appeal Board (“Board”) determined Chemco had not shown these claims were unpatentable as obvious. The Board denied Chemco’s rehearing request. Chemco ap- peals. We affirm.

The ʼ673 patent generally relates to a lime slurry recir- culation loop for the removal of unwanted grit particles and the extraction of lime slurry. The only issue on appeal is whether substantial evidence supports the Board’s find- ings that two asserted prior art references do not teach or suggest a “suction line” for extraction.

Before the Board, Chemco argued that U.S. Patent No. 5,336,481 (“Muzik”) disclosed all elements of claims 1 and 2 apart from an element requiring the extraction of slurry “via a suction line, through a stilling well, that al- lows gravity separation of grit from slurry.” ’673 patent claim 1. Chemco argued that either U.S. Patent No. 6,833,078 (“Espinoza”) or U.S. Patent No. 6,197,190 (“Hanlon”) discloses or renders obvious that element—and that, further, a person of ordinary skill in the art would have combined Muzik’s slurry loop with the stilling well disclosed in those references. Chemco thus argued that the challenged claims were unpatentable as obvious over (1) Muzik in view of Espinoza or (2) Muzik in view of Hanlon.

The Board rejected Chemco’s argument. In its final written decision, the Board found that neither Espinoza nor Hanlon discloses or renders obvious the required suc- tion line. Since Chemco relied only on Espinoza or Hanlon Case: 22-1459 Document: 46 Page: 3 Filed: 03/10/2023

CHEMCO SYSTEMS, L.P. v. RDP TECHNOLOGIES, INC. 3

to teach the suction line, the Board concluded that Chemco had not shown claims 1 and 2 unpatentable as obvious.

Obviousness is a legal question based on underlying findings of fact. Am. Nat’l Mfg. Inc. v. Sleep No. Corp., 52 F.4th 1371, 1379 (Fed. Cir. 2022). We review the Board’s legal conclusions de novo and its factual findings for sub- stantial evidence. Id. The Board’s finding that neither Espinoza nor Hanlon discloses a suction line is supported by substantial evi- dence. Chemco admits that neither reference explicitly mentions extraction of slurry via a suction line. Appel- lant’s Br. 14. And its arguments that the references im- plicitly indicate suction or that they render use of suction obvious are unpersuasive.

As the Board found, the apparatus disclosed in Espi- noza does not include a pump to create suction. J.A. 30– 31. Instead, the placement of outlet line 210 below the chamber’s fluid line permits removal via gravity flow. J.A.

30. Given this placement, the reference to “drawing off” a particle-rich stream from the top of the settling chamber in Espinoza does not have the same meaning as the ʼ673 pa- tent’s reference to “drawing off” via a suction line. J.A. 30– 31. Similarly, Hanlon does not teach a suction line or a pump. J.A. 35. And the Board found that Chemco did not sufficiently explain why a person of ordinary skill in the art would have chosen suction over Hanlon’s collecting pipe 26.

J.A. 35; see also J.A. 45. We conclude that substantial evi- dence supports these findings.

We have considered Chemco’s remaining arguments and find them unpersuasive. For the foregoing reasons, we affirm the Board’s decision.

AFFIRMED