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).
Productive Indicators at CMZ
•
•
•
•
•
•
•
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.
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.
A
F
F
L
U
Physical
Treatment
PRETREATMENT
Biological
Treatment
SECONDARY
TREATMENT
T
F
F
L
U
E
N
E
E
Large size solids,
sands
Biomass
N
T
ORIGINAL WASTE WATER TREATMENT
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 Biofilter" or “Earthworm Filter” ("Lombrifiltro)."
ORIGINAL WASTE WATER TREATMENT
Table 1: Comparison of the Tohá® System to other Traditional Technologies
Characteristics
Aerated Ponds
Activated Sludge
Tohá® System
5 m2/person
0.7 m2/person
0.25 m2/person
20 days (Chile)
6-8 hours
30 minutes
Equipment
Simple: 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
Low amount
Large amount
None
Surface
Residence Time
Sludge (Biological
sludge)
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.
ORIGINAL WASTE WATER TREATMENT
Physical Treatment
Primary Treatment
Large size solids,
sands
Biological Treatment
Secondary or
Biological Treatment
Physical Treatment
Tertiary or
Advance Treatment
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.
UV Tratment Tank
Settling 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 Camp
Number of users: 1.500 people
Manning: 190 liters/user/day
Flow 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
NCh 1333,
CONSTRUCTION EXPECTED Requirements for
CAMP
VALUES
irrigation water
quality
UNIT
OPERATIONS
CAMP
pH
UpH
6,71
7,15
5,5 - 9
DBO5
mg/l
23
21
< 30
------
Total Suspended
Solids
mg/l
15,5
12,5
< 30
------
Turbidity
Ntu
20
7
< 20
------
umhos/cm
860
1568
< 3.000
1.500 - 3.000
Total Dissolved
Solids
mg/l
599
946
< 2.000
1.000 - 2.000
Fecal Coliforms
NMP/100
ml
<2
<2
< 1.000
< 1.000
mg/l
0,015
0,051
0,1
0,1
PARAMETERS
Conductivity
Arsenic
5,5 - 9
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 agroenergetic 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