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 1994.

• Main facilities are: Primary/Secondary Crushing Plant to produce a P80 of 40 mm. Subsequent classification in screens. Oversize is sent to WF Tertiary Crushers that produce ore with P80 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 145.000 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

A

F

FL

U

E

N

T

E

F

F

L

U

E

N

T

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

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

Characteristics Aerated Ponds Activated Sludge Tohá® System

Surface 5 m2/person 0.7 m2/person 0.25 m2/person

Residence Time 20 days (Chile) 6-8 hours 30 minutes

EquipmentSimple: pumps, aeration and

disinfection

Complex: pumps, aeration tanks, sludge treatment,

disinfections

Simple: pumps and disinfection

Efficiency 80% DBO Removal >90% DBO removal > 90 DBO Removal

Sludge (Biological sludge)

Low amount Large amount None

ORIGINAL WASTE WATER TREATMENT

Primary Treatment

Secondary or Biological Treatment

Tertiary orAdvance 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 CO2, 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

Parameters Efficiency

DBO5 90-95%

Total Solids 95%

Total Nitrogen 60 to80%

Total Phosphorus 60 to70%

Fecal Coliforms 99%

BARRICK ZALDIVAR MINING COMPANY

1. Plant for Operations CampNumber of users: 1.500 peopleManning: 190 liters/user/dayFlow Rate: 285,000 liters/day.

2. Plant for Construction Camp Number of users : 1.000 people Manning : 190 liters/user/day Flow Rate : 190,000 liters/day.

.

RESULTS OF EFFLUENT QUALITY FROM PLANTS

PARAMETERS UNITOPERATIONS

CAMPCONSTRUCTION

CAMPEXPECTED

VALUES

NCh 1333, Requirements for irrigation water

quality

pH UpH 6,71 7,15 5,5 - 9 5,5 - 9

DBO5 mg/l 23 21 < 30 ------

Total Suspended Solids

mg/l 15,5 12,5 < 30 ------

Turbidity Ntu 20 7 < 20 ------

Conductivity umhos/cm 860 1568 < 3.000 1.500 - 3.000

Total Dissolved Solids

mg/l 599 946 < 2.000 1.000 - 2.000

Fecal ColiformsNMP/100

ml< 2 < 2 < 1.000 < 1.000

Arsenic mg/l 0,015 0,051 0,1 0,1

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 900.000

Water extraction cot from Negrillar: 0.81 USD/m3

Water treatment cost in plants: 0.33 USD/m3

Amount of treated and re-used water: 174 million liters/year

Monthly benefit: UDS 6.935

Reduced water extraction: 3%

Approximately: More than 6 L/s less extracted