Atna Resources Ltd. ("Atna" or the "Company") wishes to provide more detail on the announcement of May 29, 2013 advising of its intention to reduce the scale of underground mining operations at its Pinson gold mine located near Winnemucca, Nevada.
The Company has made the decision to reduce the mining rate in order to:
- Concentrate on ore mining from accessible, already developed ore stopes.
- Review and reconsider different options to improve the mine plan, in the light of experience gained during the initial development and mining completed to date. Mining and ore control methods utilized in the startup phase of the operation produced unacceptably low productivity levels, resulting in less ore production than expected in the feasibility study.
- Reduce the cash requirements for ongoing stope development while the mine plan is revised. The recent drop in gold price has impacted Atna's cash flow and financial ability to maintain an accelerated pace of development.
Atna will continue mining developed stopes with sufficient ore to maintain operations at this time while evaluating alternate options to reduce cost and improve efficiencies. Operations at the mine have been reduced from seven days per week, two shifts per day to five days per week, one shift per day. Operations are expected to continue at this level for the next four to six months as improvements are developed. Under the current operating schedule, the mine expects to continue to make ore shipments on a regular basis with timing dependent on shipping lot sizes for either oxide or sulfide ore. A second mining shift could be added at minimal cost utilizing existing equipment when justified.
"We increased mining levels in late April, but experienced low ore production levels. When combined with a mining contractor-based cost structure this resulted in an unacceptably high rate of spending that adversely impacted Atna's treasury. This impact was accelerated by a declining gold price. As a start-up operation, these issues must be addressed. We acted swiftly, choosing to downscale operations at Pinson to conserve cash and give us time to address these issues," states James Hesketh , President & CEO.
Over the last few weeks, the operations at Pinson were intensely reviewed by Atna's senior management. A significant portion of the productivity problems seen in the operation were related to the complexity of the deposit, while a portion of the problems can be attributed to the need for improvements in the information and operating systems. A number of areas have been identified for process improvement or analysis:
- A third party contractor has been retained to initiate detailed reconciliation analysis of actual mined ore as compared to the resource/reserve block model. On a high-level basis, initial indications show that the model is underperforming but correlating within a reasonable range of the reserve model in those areas actually mined. Detailed analysis is underway to compare planned mining activities to actual mining and the reserve model. The goal of this exercise is to determine what, if any, changes to the resource/reserve model may be necessary. Knowledge from this work will also allow for better mine planning.
- Mining has determined that some definition drilling was not properly oriented to provide adequate information for accurate stope design work. In other areas, ore mining commenced based on reserve model blocks without drilling. Neither approach has been acceptable. The sequencing of delineation drilling prior to mining and improvements in drill pattern design are expected to provide better information to create productive, cost-effective stope designs.
- Rapid turnaround of geologic and assay information and better coordination and use of this information by engineering and operations are expected to result in improved mining productivity.
- The waste rock at Pinson is more competent than the ores mined. The ores break down to a fine size when mined, while waste rock remains coarsely sized and can be screened from mined ores. This has been tested in Pinson's last three ore shipments and has improved the head grade of shipped products. The current mining system focuses on increasing ore recovery, while minimizing waste dilution, which reduces mining productivity and increases the cost per ton mined. Productivity might be increased by accepting a higher level of ore dilution underground. The concept of accepting increased waste dilution underground, to be screened out on the surface, will be evaluated.
- Certain areas of the OG zone may lend themselves to long-hole or other bulk mining systems, particularly if waste dilution can be accepted and screened out in the surface operations. These mining methods may be conducted at a significantly lower cost than the underhand cut-and-fill methods currently being utilized. Bulk mining methods will be evaluated as a viable mining alternative.
The Pinson spiral has been developed to the 4530 level, and three ore stoping areas are available in the OG zone on the 4740, 4650 and 4600 levels. These three OG stopes are estimated to contain over 60,000 tons of ore and are the current focus of operations. A cross-cut has been initiated towards the Range Front zone (RF) on the 4620 level, but not yet completed. In addition, the Adam Peak zone (AP) has been accessed on the 4640 and 4590 levels. Additional stope blocks that can be accessed from the existing spiral include the 4530 OG, the 4570 RF and 4540 AP stopes. The AP and RF zones have not been mined and remain untested at this time, but represent approximately 45% of total declared reserves at Pinson.
All of the stopes above the 4600 level can be mined at this time. The reserves available in stope designs above the 4600 level including all ore zones contain over 30,000 ounces of gold in approximately 100,000 tons of ore including the OG stopes discussed above. Stope blocks below this level cannot be mined without completion of a ventilation raise that has been developed at its top and bottom. The partially developed raise and escapeway can be completed at a cost of approximately $140,000. Completion of the raise will allow development of the reserves in designed stopes between the 4530 and 4600 level which contain over 65,000 ounces in approximately 220,000 tons of ore.
For additional information on Atna, its mining, development and exploration projects, please visit our website.