Nov 20 2012
American Bonanza Gold Corp. ("Bonanza" or "Company") is pleased to announce that the 100% owned Copperstone gold mine in Arizona has made significant progress during October. The focus over the recent period has been on increasing ore output from the underground mine and accelerating the development mining. The Company is encouraged with the recent progress as it continues towards its goal of achieving commercial production, now estimated for the first quarter of 2013.
Development Mining
Ore is currently available for mining in three zones, which is the initial milestone towards bringing mine output to design levels of 450 tons per day of ore. A total of four headings are being mined in ore currently. Each of the three zones is now developed with access, power distribution, water management and scout drilling for the detailed short term planning. Ore planned for extraction during the next two months is now fully developed for mining.
The main objective for the development mining program is now to provide access to two additional zones over the next month. This will provide ore available for mining subsequent to the three zones which are currently being mined. A dedicated development mining team is being assembled to continue the acceleration of the development mining.
Ore Mining
As a consequence of the development mining accelerating, ore extraction rates increased during October and continue to improve during November. Total rock mined during the first half of November exceeds the same total for the entire month of October. During the first half of October, the mine averaged 2.5 rounds per day, and during the second half of October, the mine averaged 3.1 rounds per day. For the first half of November, the mine has averaged over 4 rounds per day. 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. During October, ore mined averaged 139 tons per day, which is 31% of the design rate. Total rock mined during October averaged 291 tons per day.
Ore Processing
Ore processed through the gold plant during October has improved relative to the previous performance during the third quarter of 2012. The material processed in October has been ore mined from underground with the addition of lower grade and stockpiled material, resulting in higher tonnage processed than mined. Ore processed during October averaged 360 tons per day, which is 80% of the designed rate of 450 tons per day. The milling facility is capable of processing higher tonnage, and will do so in November as ore extraction from the mine continues to increase. Mill recovery during October averaged 72%, reflecting the effect of processing lower grade material, which impacts recovery. Feed to the mill during the beginning of November contains substantially more ore grade material from mining, and less low grade material, which has the potential to increase overall grades and thus improve recoveries.
Concentrates
Concentrate grades for the gravity circuit averaged 42 ounces of gold per ton, and the flotation concentrate grades averaged 17 ounces per ton. These concentrate grades are improvements over the third quarter performance, and continue to look strong during November. A total of 902 ounces of gold were shipped in concentrate during October.
Mine and mill performance for the full month of November will be announced during mid-December.
Mr. Brian Kirwin, President & CEO, commented: "We at Bonanza are all encouraged by recent progress from the underground mine. The gold recovery plant continues to perform well, and recent progress underground suggests that the mine is steadily improving and 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.
Source: http://www.americanbonanza.com/