Overview
The Topia Mine is situated near the town of Topia, Durango State, Mexico, approximately 235 kilometres northwest of the city of Durango. The property is accessible by road by traveling north for approximately 200 km on paved Highway 23, and west for 150 km on a paved and gravel road to Topia. The town is presently served by daily small-aircraft flights from Durango and Culiacan and is the principal centre for the area with schools, shops, a small hospital, and public telephone and internet access.
The Topia Mine (silver-gold-lead-zinc) consists of several narrow-vein, underground operations utilizing a modified cut-and-fill mining method known as ‘resuing’. The mines are typically accessed by unpaved mountain roads leading to adits that either follow the veins into the mountains or are driven to cross-cut them. The veins range from 15 to 150 cm wide, with an average of 30 cm. Broken ore is hauled by 8-tonne truck to the central processing plant on the edge of town.
The plant capacity is approximately 270 tonnes per day, consisting of a 2-stage crusher which produces a fine ore mill feed (3/4 inch), a grinding circuit consisting of three ball mills, and two conventional flotation circuits producing a high-quality silver- and gold-rich lead concentrate plus a zinc concentrate. The concentrates are transported to the Pacific port of Manzanillo, where they are sold to commodity traders. From Manzanillo, the concentrates are shipped to smelters worldwide for the extraction and refining of metals.
Topia Mine Operating Results
| 2013 | 2014 | 2015 | 2016 | 2017 | 9 mos 2018 | |
|---|---|---|---|---|---|---|
| Tonnes Ore Milled (000's) | 62 | 67 | 65 | 56 | 54 | 55 |
| Ore Silver Grade (g/t) | 351 | 343 | 356 | 354 | 376 | 351 |
| Plant Silver Recovery (%) | 90.2 | 89.9 | 90.7 | 90.4 | 91.7 | 93.5 |
| Metal Production, (000's Ag Eq oz)1 | 857 | 994 | 1,078 | 899 | 1,087 | 973 |
| Silver Production, (000's oz) | 631 | 668 | 678 | 574 | 596 | 526 |
| Gold Production (oz) | 651 | 555 | 614 | 612 | 999 | 820 |
| Lead Production (tonnes) | 1,116 | 1,154 | 1,198 | 1,034 | 1,291 | 1,484 |
| Zinc Production (tonnes) | 405 | 1,154 | 1,850 | 1,496 | 1,758 | 1,700 |
| 18.65 | 15.81 | 12.19 | 11.43 | 9.53 | 6.68 |
- Metal Production is expressed in terms of silver equivalent ounces, (Ag Eq oz), the formula for which depends on the gold, silver, lead and zinc metal prices used in each year and hence are only indicative.
- Cash cost per ounce of silver is a non-IFRS measure used by the Company to manage and evaluate operating performance at each of the Company's mines. It comprises the cost of production, cost of concentrate transportation and the cost of smelter and refining charges, net of the credit from the sale of by-product metals, (gold, lead and zinc). Refer to the "Non-IFRS Measures" section in our MD&A.
Resource Estimates
The mineralized veins at Topia are laterally extensive and can locally be followed for more than four kilometres. They are steeply dipping and, due to their narrow width, mine development is ‘on-vein’ rather than parallel to it. Consequently, the veins are drilled at wide spacing from surface to trace their lateral continuity, then detail sampled underground as development progresses. Very little underground drilling is conducted. In this way, Inferred Mineral Resources are defined primarily from surface drilling while these are upgraded to Measured & Indicated Resources once the underground sampling is complete. This methodology also proves adequate as a guide to mine planning.
For details on the current NI 43-101 Mineral Resource Estimate at Topia, refer to www.greatpanther.com/operations/resources/resources/