Agua Rica

Overview

Agua Rica copper-gold-molybdenum porphyry deposit is located 25 km north of the town of Andalgala in the province of Catamarca, Argentina. 

The project has been under exploration since the early 1960s. The property is currently owned by Yamana Gold. In 2011 was optioned to Minera Alumbrera a joint venture company owned by Xstrata Copper, Goldcorp Inc and Yamana Gold.  

The deposit is to be developed as a conventional open pit mining operation using shovels and a fleet of 290t hauls trucks. 

A 90,000 tpd processing plant is to be developed on site. Crushing and grinding would be followed by flotation and the producing of copper and molybdenum concentrates. 

The copper concentrate will be pumped through a 213 km concentrate pipeline to a filter plant at Tucuman then transported by railway to the port facilities at Rosarioon the Parana River. The molybdenum concentrate will be bagged and road transported to a facility in Chile. 

It is envisioned to produce an annual average of 526,000 t of copper concentrates containing 136,000 t of copper and 124,600 ounces of gold and 13,750 t of molybdenum concentrates containing 7,150 t of molybdenum over the 23 year life of the mine.

Location

Argentina is the second largest country in South America and the largest among Spanish speaking nations.

Evidence of humans in Argentina is 11,000 years old; in the 15th century the Inca Empire conquered only the northwest part of the country; Europeans arrived in 1516 and established the Viceroyalty of Peru in 1542. The country declared independence from Spain in 1816.

Agua Rica is a large copper-molybdenum-gold porphyry style deposit located  in northwest Argentina at the foot of Sierra Aconquija approximately 34 km due east of the operating Bajo de la Alumbrera mine and 25 km north of the town of Andalgala in the province of Catamarca. 

Andagala is a 15,000 people town which has an agriculture based economy. 

The property is surrounded by 3,500 m high mountains and deeply incised valleys. Sediment control and water erosion during the summer rainy season need to be mitigated. 

Climate is mild and arid. December and January are the hottest months (30deg C) while June through August represent the winter months with temperatures possibly dropping below 0deg C at higher elevations.

Geology and Mineralization

Agua Rica lies to the east of the Farallon Negro volcanic complex that encompasses the copper-gold Alumbrera mine. 

The Agua Rica is a large medium grade porphyry copper-molybdenum-gold deposit which had been overprinted by a later argillic alteration and high sulphidation epithermal mineralization event. 

 It is located at the contact between early Paleozoic metasediments of the Sierra Anconquija Complex and the Capillitas granites. 

Intrusive rocks that host the deposit consists of feldspar porphyries and different phases of hydrothermal breccia. Metasediments constitute the country rock for the deposit and they are mineralized at the contact with the intrusive. 

Alteration at Agua Rica is characterized by the lack of a well-preserved potassic alteration. 

Porphyry mineralization consists of pyrite, molybdenite, chalcopyrite +/- bornite and pyrrhotite. 

Total mineral reserves were calculated at 730.7 Mt grading 0.5% copper, 0.23 g/t gold, 3.64 g/t silver, 0.033% molybdenum.

Mining & Operation

Agua Rica is to be mined by conventional open pit mining methods. Mining will supply 90,000 tpd ore to the mill over a 23 year mine life. Average stripping rate is estimated at 2.13:1. 

Mining would be conducted by using purchased and leased equipment. Contractors would assist in the pre-stripping and development phases.  

A fleet of 29 145t haul trucks paired with three 22m3 diesel-hydraulic front shovels and two 20m3 wheel-loaders would work on the access road development and initial pre-stripping. After one year, a larger fleet is added i.e. 23 290t haul trucks paired with 2.40 m3 diesel-hydraulic front shovels and a single 40m3 wheel-loader. 

A fleet of four 311mm diesel powered track-mounted drills would be used for pre-production. Initial drilling will do by a smaller 152mm diesel powered track-mounted drill. 

Support equipment such as track dozers, graders, water trucks, a smaller excavator, rubber tire dozer and excavator-mounted rock breaker will also be necessary. 

A total of 1,556 million tonnes of waste would be removed.

Processing

Metallurgy of the Agua Rica ore is complex and resulted in the identification of seven different types. Two types of ore are regarded as ‘clean’ and won’t carry penalties because of low arsenic and zinc levels. 

The 90,000tpd processing plant consists of a grinding circuit, one SAG mill, and two ball mills followed by a conventional flotation circuit. 

The process starts at the mine with twin relocatable primary gyratory 60-113 crushers, one dedicated to ore and one dedicated to waste. The crushed envisioned to produce ore is then transported to the 270,000 t coarse ore stockpile (90,000 t live) located near the process plant. The waste rock is conveyed to the Cazadero valley near the mill for disposal by stackers.

The primary grinding will be performed using a single circuit of one 40 ft diameter SAG mill and two 26 ft diameter ball mills in closed circuit with cyclones. The grinding circuit will process 90,000 tpd to grind to 80% passing 150 µm. The pulp will pass through a rougher, regrind and cleaning flotation circuit, to produce a bulk copper – gold - molybdenum concentrate. This concentrate is sent to the copper/gold/molybdenum separation circuit where the molybdenum will be separated by flotation to form a saleable molybdenum concentrate.

The molybdenum concentrate will be thickened, filtered, dried and bagged for road transport, assumed to be a facility in Chile. The tailings from the molybdenum separation circuit will be the final copper-gold concentrate.

The copper concentrate will be pumped through a 213 km concentrate pipeline to a filter plant located next to the NCA rail line at Tucuman. The plant will be a stand alone filter plant with its own offices, warehouse and tree farm. The filtered concentrate will be loaded into rail cars and transported to the port facilities at Rosario on the Paraná River.

Tailings will be dry stacked in an impoundment area in the Cazadero valley, located near the mill in a desert area with limited rainfall. The same valley will be used to stack waste rock from the mine. The waste rock is potentially acid generating and the containment provided by the valley will assist in managing any water that runs off during storm events. 

Water is going to be extracted from the Campo El Arenal aquifer.

Environment & Community

The impact that the Agua Rica mining project would have on the environment would be minimal as a result of adopting adequate strategies that deal with acid rock drainage. 

Water access is another critical issue especially in the semi-arid region that hosts the project. Mitigation and management measures have been developed to address adverse effects on water quality and availability for local communities. 

The opening of the mine would create direct and indirect jobs in the region.