VANCOUVER, BRITISH COLUMBIA--(Marketwire - Feb. 25, 2013) - American Bonanza Gold Corp. (News - Market indicators)(OTCQX:ABGFF) ("Bonanza" or "Company") is pleased to announce progress at the 100% owned Copperstone gold mine in Arizona during January. During January, the tailings handling system issues that limited mill throughput were resolved and mill recoveries improved. Many aspects of the operation saw a continuation of the improving trend that the Copperstone Mine has experienced over the past few months. However, development mining, ore mining and processing were affected in January when a number of mining staff were unexpectedly affected by an outbreak of influenza that was widespread throughout Arizona and the rest of the US.
Whilst this was a short-term term event, it impacted Copperstone's manpower in January and therefore affected output and recovery performance. The mining team is now back to full strength, and early indications are that February will yield results similar to December, and that performance in March should improve further. The information below shows how the short-term influenza outbreak temporarily impacted output at the Copperstone Mine:
Production Summary (see below for detailed breakdown of figures)
|Total rock mined
|Rounds per day mined
During January, development mining extracted 4,536 tons of rock, compared to 8,752 tons during December. This was largely due to the manpower shortage experienced in January.
During January, ore was available for mining in five zones, which is similar to performance during December. This is a significant achievement towards bringing mine output to design levels of 450 tons per day of ore. A dedicated development mining team continues towards deployment during February to continue the acceleration of the development mining.
Ore extraction rates during January were impacted by the manpower shortage. Total rock mined during January averaged 463 tons per day, down from 612 tons per day in December. Ore mined during January averaged 317 tons per day, similar to production in December, with development mining averaging 146 tons per day, down from 302 tons per day during December. The average daily ore mined represents about 70% of the targeted design rate of 450 tons of ore per day, slightly better than December, and roughly double the ore mining rate in November. While tonnage of ore mined during January was similar to December, the manpower shortage impacted a number of processes including ore handling, and the average grade delivered to the mill was lower in January than December.
During January, the mine performance continued at an average of nearly 5 rounds of mining progress per day, similar to performance during December. (A round at Copperstone is eight feet of mining advance resulting from one phase of drilling, blasting and mucking. Although this varies according to rock type, one round at Copperstone generally contains roughly 100 tons of rock).
Ore tonnage processed through the gold plant during January was steady relative to performance in December. Ore processed during January averaged 322 tons per day (compared to 334 tons per day in December), which is 72% of the designed rate of 450 tons per day. The processing throughput was limited by mine output. Limitations to mill throughput that were experienced during December (tailings handling) were resolved during January.
Mill recovery during January averaged 82%, reflecting the positive effects of changes made to the flotation chemicals and how they are utilized. Ore processing rates are expected to improve when steady feed of ore grade rock is delivered to the mill from the mine. The tailings management system issues are resolved, and the mill recovery rates are improving toward the design rate of 90%.
Concentrate grades for the gravity circuit averaged 15 ounces of gold per ton (December: 48 ounces of gold per ton), and the flotation concentrate grades averaged 23 ounces of gold per ton (December: 69 ounces per ton). These concentrate grades were impacted during January by several issues resulting from the manpower shortage that month. A total of 520 ounces of gold were recovered in concentrate during January. The ounces of gold recovered during January were primarily adversely impacted by the manpower shortage, and resulting mine grade output. Provisional indications are that gold recovered into concentrate and shipped to February 19th exceed the total number of ounces of gold in concentrate for January.
Mine and mill performance for the full month of February will be announced during mid-March.
Mr. Brian Kirwin, President & CEO, commented: "We are encouraged by recent progress from the processing plant and progress with resolving the tonnage limitations in the mill and continuing improvement with the gold recovery rates. January was a difficult month because of manpower shortages, but these appear to be behind us. We look forward to bringing the Copperstone gold mine up to design throughput in the near future."
This release was reviewed by Douglas Wood, P.G., Vice President, Exploration of Bonanza, a non-independent Qualified Person within the meaning of NI 43-101.
The Company announces the resignation of Mr. Ronald Netolitzky as director of Bonanza. Mr. Netolitzkys' knowledge and experience were invaluable to the development of the Company and we thank him for his many years with Bonanza. Mr. Netolitzky is reducing his directorship in order to focus on his other business interests. We wish Mr. Netolitzky continued success in his future business endeavours.
Bonanza is operating the newly constructed Copperstone gold mine in Arizona. For more information please visit Bonanza's website at www.americanbonanza.com.
AMERICAN BONANZA GOLD CORP.
Brian Kirwin, President & Chief Executive Officer
We seek safe harbour.