JOHANNESBURG (miningweekly.com) – Having ramped up production at its Mexico-based Platosa mine, TSX-listed silver miner Excellon removed a major bottleneck and demonstrated stable fourth-quarter production despite dry mining conditions.

"We have more work to do though, as we are working through normal course transitional issues as we ramp up to higher production rates,” said CEO Brendan Cahill in a statement released Tuesday.

In October, the company successfully commissioned the second tailings management facility (TMF) at its mill in Miguel Auza, Zacatecas.

The new TMF will provide for about 19 years of capacity at a 300 t/d production rate in five stages. It replaces the original TMF, which had reached its design capacity.

The TMF is a key strategic asset in the company's plans to continue growing resources at the Platosa mine, discover additional Platosa-like deposits on the Platosa property and discover epithermal silver deposits in the Miguel Auza area.

During 2017, the company accelerated underground drilling and successfully added material amounts of mineralisation to the upper parts of the 623 Manto.

During October, production primarily came from the Pierna and Guadalupe South mantos, as ground support was required in Pierna and 623 Manto, with both mantos silled and bolted simultaneously.

Historically, intensive grouting to control water served as enhanced ground support at great cost and time.

“With grouting eliminated, the operation is incorporating normal-course bolting and screening at a much lower cost and time to advance development,” said Cahill, adding that tonnage improved considerably during the remainder of the quarter, with multiple operating faces in all four mantos.
 
More efficient installation of ground support is a key ongoing endeavour at Platosa, as the mining operation works to increase productivity to reach a steady rate of production at 300 t/d.

Meanwhile, pumping rates were lower than planned during the quarter, which impacted on overall drawdown, as repairs were required on the electrical starters on certain pumps, but were expected to return to over 30 000 gallons a minute in the coming weeks.

Drawdown was also impacted on by the refiltration of water from surface into the aquifer from two areas identified during the quarter, which have now been closed off.

By the end of the period, drawdown rates were returning to expectation. The company expects continued improvement in the first quarter of 2018.

Development rates are expected to continue to increase as headings drive into the next levels of all four mantos.

During the quarter, the company continued to process low-grade historical stockpiles and sump material, with minimal associated mining costs.

In mid-December 2017, the company began an extensive surface exploration programme on the 21 000 ha Platosa property, with 30 000 m of diamond drilling planned.

One drill rig is currently operating on surface, focused on discovering new manto mineralisation along the prospective Platosa corridor.

Drilling also continues underground to define mineralisation near existing infrastructure and around the high grade 623 Mantos, with additional underground results expected in the coming weeks.

Meanwhile, the company also announced that the accelerated conversion of all remaining outstanding 3.75% convertible debentures, due November 27, 2019 was completed on December 28, 2017.

Accordingly, the company issued just under 10-million common shares at a price of $0.50 a share and cleared all outstanding debt from the balance sheet.

"Our debenture holders allowed for us to commence the optimisation of Platosa during much less favourable equity and commodity markets. We are thankful for their trust and support at that time and for their further participation in recent equity financings.”