Privately equity firm KKR & Co LP announced it will invest more that $680 million in Preferred Sands, helping one of North America’s largest makers of sand for oil and gas producers stay in business. KKR’s special situations fund will be leading the deal, it’s a division in the company that focuses on investing in failing companies. Preferred Sands started reaching out to restructuring advisors last September, after it couldn’t make payments on its bank loans, according to Moody’s Investor Service Inc. The company’s problems have been attributed to competition in the frac sand industry and lack of high quality sand reserves, along with less developed logistical network relative to its opponents. Karlan Cherniak, a member of KKR’s special situation unit said, “We believe Preferred Sands has an enviable position in the marketplace, and this is an investment in the team, the technology, and the future of a growing platform.”