TORONTO (miningweekly.com) – Mexico-focused silver producer First Majestic Silver on Tuesday said the company's new 1 000 t/d flotation circuit at its Del Toro silver mine, in Zacatecas, Mexico, had reached Phase 1 commercial production at the start of the month.

The company said the first phase of mill construction comprised of a 1 000 t/d flotation circuit producing silver, lead and zinc concentrates.

Mill throughput since April 1, had averaged 916 t/d, and the average throughput for March was 898 t/d.

Commercial production at Del Toro was achieved in only nine weeks following the plant's inaugural ceremony late in January.

In the first six weeks of precommercial production, surface stockpiles consisting of lower-grade ore were supplied to the mill during this run-in period. Once full mechanical start-up was achieved by mid-March, higher-grade sulphide ore was supplied to the mill, allowing for the economic production of silver/lead concentrate.

Since achieving commercial production, mill head grades have averaged 190 g/t for silver, 2.9% for lead and 2.7% for zinc. This compared with average head grades for the first quarter of 166 g/t for silver, 2.5% for lead and 2.9% for zinc.

Metal recoveries also continued to improve during the ramp-up with a range of 60% to 70% for silver, 30% to 40% for lead, and zinc was undergoing testing in April.

Metallurgical recoveries in flotation were expected to reach 80% for silver, 60% for lead and 60% for zinc.

The first shipment of silver/lead concentrates was made on March 5 and as at the start of the month, 30 shipments accounted for 933 dry tons of concentrates having been shipped.

During the quarter, silver/lead concentrates had averaged 32% of lead per ton, containing 4 380 g/t of silver and 1.2 g/t of gold.

The first shipment of zinc concentrates was expected by mid-April.

Phase 2 of mill construction, on schedule to begin early in the third quarter, would include a new 1 000 t/d cyanidation circuit for a total milling capacity of 2 000 t/d.

The cyanidation circuit construction was progressing well. A new 115 000 kW power line was currently under construction from the state of Durango, and was expected to be complete early in July.

Following construction of the cyanidation circuit, the company will be producing its own silver dore bars, which will further reduce third-party smelting and refining charges.

The third phase of construction, comprising a 2 000 t/d flotation and a 2 000 t/d cyanidation circuit, remained on schedule and on budget for initial production by the third quarter of 2014.

At the combined rate of 4 000 t/d, Del Toro would produce about six-million ounces of silver, including significant amounts of lead and zinc a year, becoming the company's largest producing silver mine.

The company in February reported net income for the fourth quarter ended December 31 rose by 5% to $22.4-million or 19c a share, compared with $21.3-million or 20c a share for the same quarter of 2011, as a result of increased silver production and higher prices.

The company’s shares closed 4.20% higher at $15.64 on Tuesday on the TSX.