HGW12, 

This might interest you.

Coeur D'Alene Mines Corp have a mine which is somethwat similar to Shafter (pure silver mine)  and at a scale that we are expecting Shafter will show in the next few years (hopefully surpass it very quickly). Production started some 4 years ago and it is interesting to see how they operate and using filter press (partly installed in 2011 and delivered from Siemens). This MC Filtering process described more in detail below is a rather conventional method. The San Bartolome mine have had some power related problems disrupting production as it lies rather remote and above 4000m in Bolivia so I am glad that Shafter is where it is.  What is better is the Shafter, contrary to this mine, will process gold as well as silver. So you see gentlemen, I think you chose the right mine ;)

 

San Bartolomé, Bolivia

World’s 8th Largest Primary Silver Mine

 

Stage: Active Mining, Milling, Exploration
Location: Potosi, Bolivia (South-central Bolivia)
Type: Surface mining of unconsolidated sediments (colluvial and alluvial) and surface stockpiles
Metals: Silver
Product: Silver Doré
Ownership: Wholly-owned operations with mineral rights held through joint venture and long-term lease agreements with several independent mining cooperatives and the Bolivian state-owned mining company COMIBOL.
Land position: 9,000 acres (36.3 square kilometers)
Production: 2011 = 7.5M oz Ag
Cash operating costs1: 2011 = $9.10/Ag oz
Proven and probable reserves2: 118.1M oz Ag
Measured and indicated resources2: 55M oz Ag
Inferred resources2: 3.6M oz Ag

 

Overview

The San Bartolomé mine, located on the flanks of Cerro Rico Mountain near Potosi, Bolivia, is one of the largest pure silver mines in the world and the second largest silver mine in Bolivia. Cerro Rico, a prominent mountain in the region, stands at over 15,400 feet (over 4,700 meters). The mine, now entering its fourth year of production, has brought economic development and a strong commitment to environmental stewardship and worker safety to the community. Mining at San Bartolomé is conducted using simple, free-digging surface mining techniques that do not require drilling or blasting, which results in minimal impact to the landscape.

The San Bartolomé open pit silver mine and associated milling operation, is operated by Empresa Minera Manquiri SA (“Manquiri”), a wholly-owned subsidiary of the Company.  Access to the property and processing facilities is by paved and all-weather gravel roads leading south-southwest from Potosí. The Bolivian national mining company, Corporación Minera de Bolivia (“COMIBOL”), is the underlying owner of all of the mining rights relating to the San Bartolomé mine. COMIBOL has leased the mining rights for the surface deposits to several Potosí cooperatives. The cooperatives in turn have sub-leased their mining rights to Coeur, through Manquiri.  The silver deposits comprising San Bartolomé range from 0.5 to 4 kilometers south of the city of Potosí. Construction of processing facilities commenced in 2007 and production began at San Bartolomé in the second quarter of 2008.

Operations

The ore at San Bartolomé is mined using conventional load and haul surface mining techniques without the need for drilling and blasting. There are two types of ore being mined and processed: whole ore and screened ore. Generally speaking, all of the whole ore and some screened ore lie above the 4,400-meter elevation, with the remaining screened ore found below this elevation.

Whole ore is processed by conventional crushing and grinding using a SAG/ball mill combination and cyanide leaching in a counter-current decantation (CCD) circuit followed by silver recovery using a Merrill-Crowe process. The screened ore is mined from the lower flanks of Cerro Rico and is screened into +8 mesh and -8 mesh fractions for processing and for pumping to the tailings dam, respectively. The +8 mesh fraction is milled and processed using the same process flow as the whole ore. Product from the Merrill-Crowe circuit is smelted on site to produce a doré which is shipped to market.

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The Siemens MC Press filter press is also capable of dewatering concentrates to as low as 6% moisture content. Picture: Siemens AG

May 4, 2011 -- Three MC Press filter presses from Siemens will allow improved dry stacked tailings management at Coeur Manquiri's San Bartolome mine in Potosi, Bolivia. Coeur Manquiri is a wholly owned subsidiary of the US-based Coeur d'Alene Mines Corporation.

Located at the base of the Cerro Rico Mountain (Andes Mountains) near Potosi, Bolivia, the San Bartolome mine is one of the world's newest and largest pure silver mines. With a projected 14-year mine life, San Bartolome has proven and probable reserves of 120 million ounces of silver within gravel deposits at the base of the mountain. The mine produced 7.5 million ounces of silver in 2009, its first year of production. Its mountaintop location and limited available land for dewatered material made dry stacking the most viable storage option. Apart from the MC Press filter presses for dewatering, Siemens also supplies some aftermarket parts to help Coeur Manquiri ensure uninterrupted mining operations.

Dewatering tailings to higher degrees than paste produces a dry cake. These unsaturated tailings are usually hauled by truck or via conveyor to a tailings deposit where they are spread and compacted. Known as "dry stacking," this stable form of storage requires a smaller footprint, is ideal for sloped terrain, and it generally allows for easier reclamation at the end of mine life.

Coeur Manquiri also uses J-Press filter presses from Siemens at the silver recovery plant. They were installed years ago as part of the Merrill-Crowe process, which is a zinc dust precipitation method used to separate silver from a cyanide solution.

The MC Press dewatering filter presses are expected to become operational later this year.

-----------------------------------------------------------------------------------------------------------------------------------------------------Geology and Exploration Potential

San Bartolomé has been extensively explored by pits and trenches. Current exploration is being conducted to define and enlarge the known surface silver-bearing deposits and to discover additional deposits near Cerro Rico and the ore processing facility at San Bartolomé.

The operation exploits mineral reserves from four deposits located on the flanks of Cerro Rico and the surrounding areas near Potosí. These deposits are known as Huacajchi, Santa Rita, Diablo Este and Diablo Norte. These alluvial and colluvial deposits were formed by the erosion of disseminated mineralization in the upper portions of Cerro Rico. It is composed of Tertiary-aged volcanic and intrusive rocks that were emplaced into and over older sedimentary and volcanic basement rocks.

The silver mineralization at San Bartolomé is hosted in unconsolidated sediments (pallacos), reworked sediments (sucus and troceras) and oxide stockpiles (desmontes) from historic mining that occurred on the flanks of Cerro Rico. Silver, along with tin and base metals, is located in multiple veins, veinlets and stockworks that occur in a northeast trending belt which transects Cerro Rico. The upper parts of the Cerro Rico mineralized system were subsequently eroded and re-deposited into the flanking gravel deposits. Silver is hosted in all portions of the pallacos, sucus and troceras with the best grades segregated to the coarser-grained silicified fragments. These deposits lend themselves to simple, free digging, surface mining techniques and can be extracted without drilling and blasting.

In 2011, a new program of exploration trenching and sampling was performed at San Bartolomé. The trenches were dug to obtain samples to expand the mineral resources and reserves. This program is the first such exploration sampling conducted since before production began.

Outlook

The exploration trenching program in 2012 focuses on areas that can augment the near-term mine plan and will then shift to new targets to locate silver-bearing deposits. In addition, the Company is evaluating the expansion potential to produce tin with the addition of a tin recovery circuit.

2012 production at San Bartolomé is expected to be 6.2 to 6.3 million ounces of silver. San Bartolomé’s proven and probable reserves measured 118.1 million ounces of silver at year-end. Measured and indicated resources totaled 55 million ounces of silver and inferred resources were 3.6 million ounces of silver.