U.S. Silica's SandBox Unit Scores Another Win At the Patent Office on Key Patent Claims

KATY, Texas, Feb. 15, 2019 /PRNewswire/ -- U.S. Silica Holdings, Inc. (NYSE: SLCA) announced today that the United States Patent Office has confirmed two key claims of a patent which covers fundamental aspects of technology owned by its SandBox Logistics(TM) business unit. This win marks the second IPR victory for SandBox, the first coming when the Patent Office rejected all of Proppant Express' (PropX) challenges to a different SandBox patent. PropX is now judicially estopped from making the same or similar arguments again in any future infringement proceedings involving this patent.

"We are very pleased that the Patent Office has once again confirmed key claims in our patent portfolio,'' said Bryan Shinn, U.S. Silica president and chief executive officer. ''The SandBox portfolio has stood up very well in the IPR process, an especially challenging venue for patent holders. Our successes, including a complete victory against an earlier IPR filed by PropX, validate our belief that we have important and valid intellectual property, which we will continue to vigorously enforce," he concluded.

About U.S. Silica

U.S. Silica Holdings, Inc. is a performance materials company and is a member of the Russell 2000. The Company is a leading producer of commercial silica used in the oil and gas industry, and in a wide range of industrial applications. Over its 119-year history, U.S. Silica has developed core competencies in mining, processing, logistics and materials science that enable it to produce and cost-effectively deliver over 1,500 diversified products to customers across our end markets. U.S. Silica's wholly-owned subsidiaries include EP Minerals and SandBox Logistics(TM). EP Minerals is an industry leader in the production of products derived from diatomaceous earth, perlite, engineered clays, and non-activated clays. SandBox Logistics(TM) is a state-of-the-art leader in proppant storage, handling and well-site delivery, dedicated to making proppant logistics cleaner, safer and more efficient. The Company currently operates 27 production facilities. The Company is headquartered in Katy, Texas and has offices in Frederick, Maryland, Reno, Nevada and Chicago, Illinois.

U.S. Silica Holdings, Inc.

Michael Lawson
Vice President of Investor Relations and Corporate Communications
(301) 682-0304

Nick Shaver
Investor Relations Manager

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SOURCE U.S. Silica Holdings, Inc.