By Mike Yamamoto, managing editor of OptionMonsterNEW YORK ( Option Monster) -- Coal miners have been showing signs of life after getting hammered all year, and bullish traders are now focusing on Alpha Natural Resources ( ANR). More than 12,000 September 7 calls traded in a strong buying pattern Wednesday as prices doubled from 12 cents to 24 cents, according to OptionMonster's real-time tracking systems. The volume was well above the strike's previous open interest of 8,648 contracts, indicating that new positions were initiated. These calls lock in a $7 purchase price for the stock through mid-September no matter how far it might rise, but they will expire worthless if ANR remains below that level. Wednesday's action followed heavy short-term call buying in contracts that expired last Friday, which resulted in many trades that saw exponential gains. Alpha Natural shares rose 5.51 percent yesterday to close at $6.13. The stock began the year above $10 but trended steadily lower until finding recent support around $5, and it has risen sharply while breaking above its 50-day average in the last week. Total option volume in the name yesterday was more than triple its daily average for the last month. Overall calls outnumbered puts by 5 to 1, further reflecting the session's bullish sentiment. Yamamoto has no positions in ANR.