OLD TOWN, Maine — When Chinese investors touched down in Old Town more than a year ago, they stunned residents with not only the purchase of the shuttered mill, but also a unique grand-opening celebration — a feng shui cleansing. The mill’s newest owner, Zhang Yin, who made Forbes’ list of China’s richest in 2019, is well-known for her multi-million-dollar company, Nine Dragons Paper (Holdings) Ltd., the leading producer of containerboard in China. The Old Town mill is operated by an Illinois-based subsidiary of the company called ND Paper LLC, which also oversees the Rumford mill. The purchase may have come as a surprise to some locals who were previously uncertain about the mill’s future.