The Topia silver-gold-lead-zinc mines are small, narrow-vein, underground operations utilizing a modified cut-and-fill mining method known as resuing. The ore is processed to produce separate high quality, precious metal-rich, lead and zinc concentrates. The concentrates are transported to the Pacific port of Manzanillo, Mexico, where they are sold to commodity traders. From Manzanillo, the concentrates are shipped to smelters worldwide for the extraction and refining of metals. Gold, silver and lead are recovered from the lead concentrate while zinc plus a small quantity of silver are recovered from the zinc concentrate.
Silver production for 2012 totaled 555,710 oz Ag.
Operations consist of multiple small, narrow-vein mining operations, with as many as 14 separate mines mining 16 separate veins. The mines are typically accessed by unpaved mountain roads leading to adits which either follow the vein into the mountain or are driven to cross-cut the vein. The veins range from 15 to 150 cm wide, with an average of 30 cm. The mining method is known as resuing, a labour-intensive, modified cut-and-fill system, where the waste-rock fill is mined from the adjacent wall rocks. Broken ore is hauled by 8-tonne truck up the mountain roads to the processing plant. The main access to the Argentina mine and vein is located near the processing plant and is equipped with a bored shaft. In the future, it is planned to utilize this shaft to hoist ore.
The processing plant consists of a 2-stage crushing section, producing a (3/4 in.) fine ore mill feed; a grinding section, consisting of three ball mills, one larger unit with two smaller spares, and two conventional flotation circuits producing a silver-rich lead concentrate plus a zinc concentrate. The plant capacity is approximately 270 tonnes per day. In addition to processing ore from the company's mines the plant custom mills approximately 11,000 tonnes per year of ore from other local mines.