ECOLOGICAL SEWAGE WATER TREATMENT FACILITY FOR THE CONSTRUCTION CAMP OF COMPAÑÍA MINERA ZALDIVAR LTD.

General Location Compañía Minera Zaldívar is located in the Region of Antofagasta, 1400 km from Santiago de Chile and 175 km southeast of the Capital of the Region of Antofagasta. The minesite is located 3200 above sea level in one of the driest regions in the world, characterized by a very high solar radiation. There is high saline concentration in soils and climatic conditions determine scarse to null presence of vegetation. Ambient temperatures range from -7° to a maximum of 21° Centigrade. Average humidity is 15%. Annual precipitation is below 2 to 3 mm of water (or snow).

Open pit copper mine, started productive operations in Main facilities are: Primary/Secondary Crushing Plant to produce a P 80 of 40 mm. Subsequent classification in screens. Oversize is sent to WF Tertiary Crushers that produce ore with P 80 of 11 mm, which is sent to double deck screen with the fine fraction sent to flotation. After dewatering, oversize is sent to stacking to feed the dynamic leach pad. Ore stacked has a grain size 100% below 16 mm with a maximum fines ratio of 11%. The leach pad is of dynamic characteristics with a leach cycle of approximately 350 days. Bioleach (bacterial leach) is done at the dynamic pad to dissolve the copper content both from oxide and sulfide ore. There are two other types of leach pads: Secondary High Grade Spent Ore (RAL) and ROM Dump Leach. Subsequent to leaching, leach solution of 3 to 4 g of Cu/L is sent to solvent extraction where copper increases to 46 or more grams of Cu/L that will be subsequently deposited in stainless steel plates through electro-winning to produce high purity copper cathodes. Copper cathodes production is approximately t/a. Productive Indicators at CMZ

ORIGINAL WASTE WATER TREATMENT For more than 10 years, waste water disposal process was carried out at Minera Zaldívar, through primary anaerobic process of solid-liquid separation, denominated septic tank, and subsequent transport of clear water to an infiltration camp with the subsequent loss of resource which, given its chemical and biological characteristics, made reutilization impractical. PRE- TREATMENT SECONDARY TREATMENT Physical Treatment Biological Treatment Large size solids, sands Biomass AFFLUENTAFFLUENT EFFLUENTEFFLUENT

Advantage: 1.No significant energy requirements are needed in a septic tank system Disadvantages: 1.Waterproofing of the infiltration channels, especially on low absorption capacity ground, which implies the generation of odors, water upwelling, and often creates infectious and vector focus. 2.It demands periodic removal of settled sludge. 3.The effluent treated from septic tanks cannot be reused and does not meet environmentally approved irrigation standards or disposal to surface water. ORIGINAL WASTE WATER TREATMENT

Our commitment to responsible use of natural resources has led Compañía Minera Zaldívar to implement an innovative wastewater treatment process, whose main virtue is being an ecological treatment system, of low investment and operating cost. The wastewater treatment plant, which was developed in cooperation with the Found for Technology Transfer of Universidad de Chile (Untec) corresponds to what is technically denominated a "Dynamic Aerobic Bio- filter" or “Earthworm Filter” ("Lombrifiltro)."

ORIGINAL WASTE WATER TREATMENT Waste water treatment consists of a series of physical, chemical and biological processes intended to remove contaminants present in water. The intent of the treatment process is to produce clean water (or treated effluent) that can be re-used environmentally. Table 1: Comparison of the Tohá® System to other Traditional Technologies CharacteristicsAerated PondsActivated SludgeTohá® System Surface5 m 2 /person0.7 m 2 /person0.25 m 2 /person Residence Time20 days (Chile)6-8 hours30 minutes Equipment Simple: pumps, aeration and disinfection Complex: pumps, aeration tanks, sludge treatment, disinfections Simple: pumps and disinfection Efficiency80% DBO Removal>90% DBO removal> 90 DBO Removal Sludge (Biological sludge) Low amountLarge amountNone

ORIGINAL WASTE WATER TREATMENT Primary Treatment Secondary or Biological Treatment Tertiary or Advance Treatment Physical Treatment Biological Treatment Physical Treatment Large size solids, sands Biomass

FLOWCHART OF THE TREATMENT SYSTEM

PREVIOUS SYSTEMS: GRID TANK AND RISER TANK These are the units in charge of separating solids, pumping and sending the effluent to the “Toha System”: Buried Grid Tank, made up by separating screens for solids contained in the effluent. The Riser Plant, contains a fine basket to separate smaller diameter solids and also a battery of programmed pumps the boost the effluent to the “Toha System” by means of an aspersion networks.

BIOLOGICAL TREATMENT UNIT Main treatment units made up by filtering beds and earthworms that together with aerobic microbiology degrade organic matter, converting it in humus, water and CO 2, mainly

SETTLING AND DISINFECTION Post treatment units in charge of settling the humus generated by the Toha Systems and get rid of fecal coliforms to subsequently accumulate water and reuse it for irrigation. Settling Tank UV Tratment Tank

ADVANTAGES No sludge generation and by product is used as natural fertilizer Low investment and Operating Meets all the standards of environmental discharge, irrigation, DS90/2002. No generation of odors Modular system, can be expanded and easy to operate Efficiency is equal to or higher than traditional technology, no use of chemical reagents or toxic substances damaging the environment

REMOVAL PARAMETERS BY DESIGN ParametersEfficiency DBO590-95% Total Solids95% Total Nitrogen60 to80% Total Phosphorus60 to70% Fecal Coliforms99%

BARRICK ZALDIVAR MINING COMPANY 1. Plant for Operations Camp Number of users: people Manning: 190 liters/user/day Flow Rate: 285,000 liters/day. 2. Plant for Construction Camp Number of users : people Manning : 190 liters/user/day Flow Rate : 190,000 liters/day..

RESULTS OF EFFLUENT QUALITY FROM PLANTS PARAMETERSUNIT OPERATIONS CAMP CONSTRUCTION CAMP EXPECTED VALUES NCh 1333, Requirements for irrigation water quality pHUpH6,717,155,5 - 9 DBO5mg/l2321< Total Suspended Solids mg/l15,512,5< TurbidityNtu207< Conductivityumhos/cm < Total Dissolved Solids mg/l599946< Fecal Coliforms NMP/100 ml < 2 < Arsenicmg/l0,0150,0510,1

RE-USE OF TREATED WATER Treated water from plants is used for watering roads. Part of the water is used in an experimental station to develop agro- energetic crops at site. Humus generated is used as fertilizer in the same plantation.

BENEFITS Construction Cost of Plants: UDS Water extraction cot from Negrillar: 0.81 USD/m 3 Water treatment cost in plants: 0.33 USD/m 3 Amount of treated and re-used water: 174 million liters/year Monthly benefit: UDS Reduced water extraction: 3% Approximately: More than 6 L/s less extracted