El BoleoMon, 10/21/2013 - 17:25
El Boleo is an advanced stage copper-cobalt-zinc-manganese project that is located along the east coast of the Baja peninsula centred on the port town of Santa Rosalía in Baja California Sur. The property covers a series of sediment-hosted stratabound copper deposits. The geological setting is a shallow near-shore marine basin containing Pliocene and Pleistocene terrigenous clastic sedimentary rocks (conglomerates and sandstones) with several extensive relatively thin but continuous tuff layers. Deposits of copper-cobalt-zinc-manganese mineralization in the Boleo District occur within seven widespread, stratiform clay-rich horizons or beds known as manto deposits. Copper and cobalt, with variable amounts of zinc and traces of lead, as well as locally mineable bodies of manganese oxide, are related to the tuff layers interbedded with the coarse clastic sedimentary rocks. The seam formation and low material strength of the manto deposits suggests that conventional “soft rock” mining methods such as those used in underground coal, potash or salt mining would be successful.
The deposit was continuously mined predominantly by underground methods from 1886 to 1972, during which time an estimated 18 million tonnes of ore were treated. After 1972 both underground and open pit mining was carried out sporadically until the copper smelter at Santa Rosalía closed in 1985. Since cessation of mining operations, International Curator carried out exploration between the years 1993 to 1998, and Minera y Metalúrgica del Boleo (MMB) has been carrying out exploration and project development activities from 2001 to the present. In August 2013, Korea Resources Corporation contributed US$74.7 million in construction funding to MMB, which completed the final components of the committed pro rata contributions of the Phase II funding requirement of US$443.4 million to advance the construction of the project and reduced the interest of Baja Mining, the other shareholder in MMB, to 10%
The Boleo Project is being developed as a series of underground mines using the room-and-pillar mining method, along with small open pit mines. This method was chosen to deliver the targeted plant feed grade at the required rate because of its flexibility for layout designs, efficient recovery of resources, and lower initial capital cost. The ore will be fed to a processing plant, which will use a two-stage leaching circuit, followed by solid liquid separation, and solvent extraction electro winning to produce copper and cobalt as metal, zinc as zinc sulfate monohydrate, and there is a possibility of producing manganese, as manganese carbonate. The plant is expected to produce 57,000 tonnes for the first 6 years at an average grade above 2% and 38,000 tonnes of copper per year thereafter at an average grade of 1.33%. Based on present reserves and the current mine plan, the scheduled life of mine is 23 years, and the project will begin production in early 2014.