A Harlan County coal miner has died from injuries he sustained weeks ago in a surface mining accident. Twenty-eight-year-old David Middleton died in a hospital yesterday.Middleton of Baxter was injured two weeks ago when a bulldozer he was driving overturned on a Harlan County surface mine. Middleton was working to reclaim the Mill Branch Mine, which is owned by Nally and Hamilton.Middleton’s death is the eighth coal mine-related fatality in Kentucky this year. Half of those deaths have happened during the past three weeks. The Kentucky Office of Mine Safety and Licensing plans to conduct enhanced on-site training this week to increase awareness of the issues that have contributed to the recent accidents.