* Adjusted loss/share $0.01 vs est $0.31
* Revenue falls 19 pct
* Shares rise 2 pct before the bell
Oct 29 (Reuters) - Arch Coal Inc said costs for the full year would be lower than its expectations after posting a smaller-than-expected quarterly loss as lower expenses helped blunt weak prices for coal.
The company expects full-year average cash costs of $10.40- $10.60 per ton for its Powder River Basin operations, lower than $10.45-$10.85 it forecast earlier. Average cash cost forecast for the Appalachian operations was trimmed to $65-$69, from $65.50- $69.50.
The third-quarter marked the best cost-per-ton performance in 10 consecutive quarters in the Powder River Basin, the company said.
Shares of the company rose 2 percent in trading before the bell on Tuesday.
"We are re-aligning our portfolio to focus on those core assets with the best long-term value and growth potential, particularly the Powder River Basin thermal franchise and the Appalachian metallurgical coal platform," Chief Executive John Eaves said in a statement.
Coal miners across the United States are discarding high-cost operations and rival Consol Energy Inc said on Monday that it would sell five West Virginia coal mines amid regulatory uncertainty.
Arch Coal posted a net loss of $128.4 million, or 61 cents per share, in the third quarter ended Sept. 30, compared with a profit of $45.8 million, or 22 cents per share, a year earlier.
Excluding one-time items, the company's loss was one cent per share. On that basis, the average analyst estimate was a loss of 31 cents per share, according to Thomson Reuters I/B/E/S.
Cash costs per ton fell 11 percent in the third quarter, while average sales price per ton fell 12.5 percent.
Revenue fell 19 percent to $791.3 million on weak coal prices, missing analysts' expectations of $888.8 million.
Abundant shale gas supplies are prompting power producers to switch to natural gas from coal, depressing prices for thermal coal, while prices for metallurgical coal are down on weak steel demand and excess supply in China.
Arch Coal shares closed at $4.16 on the New York Stock Exchange on Monday.