BUCKSPORT — The Verso paper mill closed in 2014, but three years later, a new type of wood-based industry might be starting at the old mill site. Last month, the Searsport-based business Maine Biomass Exports Inc. started stacking logs of hemlock on a former wood yard at the site. The business has a six-month contract to lease the land from AIM Development, which owns the property. Once they arrive at the wood yard, the logs are debarked and trucked to Boston. The bark is used to make mulch, while the logs are shipped from Boston to manufacturers in China, according to Arthur House, the president of the business. “Right now we’re putting logs on trucks and sending them to Boston and sending them to China,” he said. House said he employs a dozen people at the site and has brought in $1.8 million worth of equipment to debark the logs and put them on trucks.