Sumatra Copper & Gold: High grade underground production commences
Monday, November 23 2015 - 12:47 AM WIB
ASX-listed Sumatra Copper & Gold plc said Monday that the southern cutback to the existing Belinau open pit at its Tembang gold and silver project in southern Sumatra has advanced as planned with the first underground development drive now into high grade ore on Level 1 (45m RL).
The company said in a statement that this re-optimized mine plan provides a second access into the Belinau ore body from underground to deliver additional high grade feed to the processing plant which is now operating at nameplate capacity.
?Gold and silver assay results received up to November 20, 2015 from grade control face channel samples along this ore drive have been impressive. The assay results exceed resource model estimates and confirm the high grade nature of the deposit even at the outer margins of the resource. Significant composite grade control face samples along the Belinau development,? Sumatra Copper said.
It added that open pit development is progressing as planned with Berenai and Asmar supplying the majority of ore to the processing plant.
As noted in the company?s quarterly activities report for the period ended September 30, 2015, the combined effect of commissioning the processing plant 8 weeks ahead of schedule, the earlier than anticipated ramp-up of the processing plant to nameplate capacity and a delay in the permitting and delivery of explosives has led to a shortfall in supply of high grade ore from the open pits and the Belinau underground mine. The company is therefore focusing on establishing multiple underground development headings at Belinau to accelerate high grade ore production. ?Fine tuning of the open pit schedules is also continuing with a view to optimizing the delivery of higher grade ore,? the firm said.
The gold and silver head grade at the processing plant has progressively been increasing as planned:
? Mill feed for the commissioning period during September to October 2015 averaged 0.57 g/t Au and 12.2 g/t Ag (0.73 g/t Au_Eq)1.
? The mill feed blend for November 2015 month-to-date is 1.14 g/t Au and 34.2 g/t Ag (1.63 g/t Au_Eq) which is a 95% improvement in gold grade.
? Over the past week (leading up to 21 November 2015) the mill feed grade was 1.51 g/t Au and 44.0 g/t Ag (2.09 g/t Au_Eq) with Belinau comprising 13% of the feed blend.
? Plant operating time over the past 4 weeks has been in excess of 90%.
Sumatra Copper said the mill feed head grade is expected to steadily increase as additional higher grade ore is accessed from the open pits and underground:
? Dewatering of the Belinau open pit is complete and a second portal accessing Level 2 from the open pit is expected to be completed within the next week.
? The longhole stoping drilling rig has arrived in Jakarta and is expected to clear customs shortly.
? Conventional longhole stoping of Level 1 at Belinau is expected to commence in late December 2015.
? The small cutback at the Bujang pit targeting near surface, high grade ore has been successfully completed. High grade ore remains exposed in the pit wall and pit floor and the Company is evaluating the option of accessing this ore via underground development.
? Additional higher grade zones in Asmar are being defined through grade control drilling and geological mapping.
? Open pit mining at Berenai is progressing to lower benches where the resource grade is higher. The higher grade Nuri vein adjacent to the Berenai vein is expected to be accessed in the first quarter of 2016 providing another high grade open pit feed source.
? Pre-stripping at Siamang has already commenced and is expected to continue into the first quarter of 2016.
Significant face channel assay results (>1 g/t Au) from Belinau Level 1 underground to 20 November 2015
| Sample # | Easting | Northing | Elevation | From | To | Length | Individual | Composite | Comments | |||
| Au g/t | Ag g/t | Length | Au g/t | Ag g/t | ||||||||
| 4000184 | 41132 | 82426 | 46.6 | 0.00 | 1.00 | 1.00 | 1.96 | 116 | 1.85 | 3 | 131 | QVN, br, oxidized. |
| 4000185 | 41132 | 82425 | 46.6 | 1.00 | 1.85 | 0.85 | 4.46 | 149 | QVN, br, oxidized. | |||
| 4000192 | 41126 | 82420 | 46.6 | 0.00 | 1.00 | 1.00 | 2.53 | 200 | 1.00 | 3 | 200 | QBR, oxidized, 2 %
black sulphides banded. |
| 4000196 | 41124 | 82420 | 46.4 | 0.00 | 1.00 | 1.00 | 8.03 | 440 | 2.00 | 7 | 490 | QVN |
| 4000197 | 41124 | 82419 | 46.2 | 1.00 | 2.00 | 1.00 | 6.08 | 540 | QVN | |||
| 4000200 | 41116 | 82416 | 45.9 | 0.00 | 1.00 | 1.00 | 29.80 | 340 | 2.00 | 20 | 280 | QVN |
| 4000203 | 41116 | 82415 | 45.7 | 1.00 | 2.00 | 1.00 | 9.75 | 220 | QVN | |||
| 4000206 | 41115 | 82416 | 45.9 | 1.00 | 2.00 | 1.00 | 28.60 | 980 | 1.50 | 30 | 1,053 | QVN |
| 4000207 | 41115 | 82414 | 45.7 | 2.00 | 2.50 | 0.50 | 32.00 | 1,200 | QVN | |||
| 6000002 | 41113 | 82416 | 46.5 | 1.00 | 2.00 | 1.00 | 24.90 | 1,020 | 2.00 | 32 | 970 | QVN |
| 6000003 | 41113 | 82414 | 46.6 | 2.00 | 3.00 | 1.00 | 40.00 | 920 | AND, 20 % Quartz | |||
| 6000006 | 41110 | 82412 | 46.4 | 1.00 | 2.00 | 1.00 | 11.60 | 12 | 3.00 | 25 | 25 | QVN |
| 6000007 | 41110 | 82413 | 46.4 | 2.00 | 3.00 | 1.00 | 59.70 | 60 | AND, gr, Ar alt, Quartz
30 % |
|||
| 6000008 | 41109 | 82414 | 46.4 | 3.00 | 4.00 | 1.00 | 4.46 | 4 | AND, gr, Ar alt | |||
Editing by Reiner Simanjuntak