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The use of seawater as process water at Las Luces coppermolybdenumbeneficiation plant in Taltal (Chile)

Patricio A. Moreno a,, Hal Aral b,c, Jacqueline Cuevas d, Andrs Monardes e, Marcelo Adaro e, Terry Norgate b,c,Warren Bruckard b

a Diego Portales University, Ejrcito 441, Santiago, Chileb CSIRO Process Science and Engineering, Box 312 Clayton South, Victoria 3169, Australiac Minerals Down Under National Flagship, CSIRO, Australiad Centro de Investigacin Cientfico Tecnolgico para la Minera (CICITEM) Avda. Jos Miguel Carrera N. 1701; 4to piso, Antofagasta, Chilee Las Cenizas Mining Group, Calle Coronel 2354, Providencia, Santiago, Chile

a r t i c l e i n f o

Article history:

Received 4 January 2011

Accepted 15 March 2011

Available online 8 April 2011

Keywords:

Process water

Seawater

Saline water

Copper flotation

Milling

Tailings water reuse

Water recycle

a b s t r a c t

Las Luces is a coppermolybdenum beneficiation plant in Taltal (Chile), owned by the Las Cenizas Mining

Group (Grupo Minero Las Cenizas) of Chile. The plant comprised of conventional crushing, grinding and

flotation facilities. Las Luces has treated 720,000 tpa ore since 1995. This ore was supplied from Las

Cenizas own underground mines operating in the area.

Seawater is brought to the plant froma distance of 7 kmand pumped to analtitude of 178 m.In the Las

Luces plant, seawater is mixed with tailings dam water in theIndustrial Storage Pond. The mixed water is

used in the grinding and flotation circuits. The Las Luces beneficiation plant has been successfully using

seawater for over 15 years through a clever water recirculation scheme. The Las Luces plant is unusual in

the sense that it has operated during this time without the use of any fresh water.

Analytical data show that the dissolved salt content of the process water has increased from 36.0 g/L to

46.4 g/L or 0.7 g/L/year. Calculations suggest that this increase is largely due to solar evaporation where

the evaporation rate reaches 50 m3

/hectare/day.In Las Luces, the evaporation related water losses amount to 237 megalitres/year or a loss of approxi-

mately 69 days of seawater pumping to the Industrial Storage Pond. Based on this finding Las Cenizas is

now investigating options to minimise the loss of water to evaporation.

2011 Elsevier Ltd. All rights reserved.

1. Introduction

The Las Cenizas copper mines, owned by the Grupo Minero Las

Cenizas S.A., has two mining and mineral processing operations in

northern and central Chile: Taltal and Cabildo, respectively. In

Taltal, the mining group operates five underground copper mines,

namely Las Luces, Altamira, Tropezn, Doa Elba and Filomena

(Fig. 1). The Cabildo deposits are located in the Fifth Region ofValparaso, 165 km north of Santiago. Doa Elba and Filomena

mines are 35 km South East from Taltal city. Tropezn, Las Luces,

Altamira mines are located 46, 55 and 110 km South East from

Taltal city, respectively. The ore types, reserves and grades of Las

Cenizas mines are shown in Table 1.

The copper, molybdenum, silver and gold deposits of the region

were formed during Late JurassicEarly Cretaceous age and are

part of a 1000-km-long belt parallel to the Pacific coast (Sillitoe

and Perell, 2005). These deposits are usually hosted by sub-aerial

andesites or broadly contemporaneous gabbro to granodiorite

intrusions formed during the early stages of the Andean magmatic

arc formation (Sillitoe and Perell, 2005). This intrusion crosscuts

the dominant granodiorite and monzogranite of the Cerro del

Pingo Plutonic Complex.

The mineralisation in the region is strongly associated with a

pervasive and zoned potassic(calcic) alteration. For example, the

bulk of the CuMo(Au) mineralisation at Tropezn is related tothe CaFeK alteration zone and includes chalcopyrite, molybde-

nite, bornite, and gold (Tornos et al., 2010).

Process water scarcity is a particular concern in places like

northern Chile where underground water reserves are negligible

or non-existent. Existing reserves are not replenished due to the

lack of rain. The only water available to Las Luces is seawater.

In this paper a brief introduction to the unit operations

employed in the Las Luces beneficiation plant is given. More

importantly, the flow rates and chemical analyses of the water

samples collected from main unit operations at the plant are pre-

sented and the variations in the chemistry of the recycled seawater

as a result of grinding and flotation are discussed.

0892-6875/$ - see front matter 2011 Elsevier Ltd. All rights reserved.doi:10.1016/j.mineng.2011.03.009

Corresponding author. Tel.: +56 2 676 2415; fax: +56 2 676 2402.

E-mail address: [email protected] (P.A. Moreno).

Minerals Engineering 24 (2011) 852858

Contents lists available at ScienceDirect

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2. Ore treatment

The Las Cenizas ores are treated in the Las Luces beneficiation

plant, located 45 km South East from Taltal. This plant comprises

crushing, milling and flotation unit operations. A variety of ores

is supplied to the Las Luces beneficiation plant from the neighbour-ing Las Cenizas mines at a rate of 60,000 metric tonnes/month. Ore

grades and recoveries by ore type are listed in Table 2. The

Altamira ore contains significant silver values, 31 g/t, and the silver

recovery is around81%. Over 50% of the ore treated at the plant site

is from the Las Luces mineral deposit, which gives its name to the

plant. The chemistry of the Tropezn ore is distinctly different from

the other ore types as it contains higher amounts of sulphides, cop-

per, molybdenum, magnesium, iron, cobalt, nickel, small amounts

of gold but lower concentrations of Al, Ca, Na and Ti.

The gangue mineralogy of the Tropezn ore is quite different

from the other ore types. The qualitative X-ray diffraction (XRD)

data shown in Table 3 indicates the presence of siderite and talc

as unique gangue minerals and sulphide minerals such as chalco-

pyrite, molybdenite and pyrite. Calcite and hematite are typicallyabsent in the Tropezn ore. This ore type, with values of 2.5%

copper, and 0.5% molybdenum also has important values of gold

(0.55 g/t), of which 71% is recovered.

The ore received from Las Luces, Altamira and Tropezn, are

stockpiled in different heaps, and treated according to their miner-

alogical characteristics.

2.1. Crushing, grinding and sizing

The ores are subjected to 3-stage crushing and primary grinding

prior to flotation.

The comminution circuit is comprised of a primary jaw crusher,

a secondary cone crusher, a double deck screen, two tertiary cone

crushers, and a double deck tertiary screen. The grinding circuit

consists of three parallel lines. The first and second lines operate

with Kennedy Van Saun ball mills (3.51 m by 4.27 m long), and

the third one with a Hardinge mill (2.74 m by 3.66 m long).

The ground ore is classified by hydrocyclones where the oversize

(coarse cyclone under flow) particles are returned to the mill for

re-grinding (Monardes and Bouso, 2009). The undersize particles

(cyclone overflow) are sent to the floatation plant. The ore isground to P80 of 147 lm. Each ore has a different hardness, varying

Fig. 1. Location map for Las Cenizas mines: Las Luces, Doa Elba, Tropezn, Filomena and Altamira in the vicinity of Taltal (Regin II) with respect to a partial map of Chile.

Table 1

Ore types, reserves and grades of Las Cenizas mines near Taltal city.

Mine Mining type Reserves Grade Mineralisation

Tropezn 46 km SE

from Taltal;

1250 m altitude

Underground stope and pillar

method

1 Mt sulphide ore

0.5 Mt copper oxides

Hypogene ore $1% Cu in the upper zone and $0.13% Moin the lower parts; present study: Cu = 5.77%;

Mo = 0.54%; Ag= 5 g/t

CuMo(Au)

chalcopyrite

Las Luces 56 km

south of Taltal;

184 m altitude

2500 t/d underground sublevel

open stoping operation at

600 m depth

7 M t Present study: Cu = 1.37%; Mo = 21 g /t; Ag = 4 g /t Chalcocite, bornite,

and chalcopyrite

Doa Elba 35 km SE

from Taltal; 850 maltitude

Underground stope and pillar

method

3.99 Mt 1.26% CuS Cu = 1.26%; Ag = 10 g/t Chalcocite and bornite

Altamira 110 km SE

from Taltal;

1250 m altitude

Underground Sublevel Open

Stoping; Av. ore prod. rate

12,000 t/y

2.5 Mt sulphide ore at

1.7% Cu; 9.0 Mt at

1.25% Cu

Present study: Cu= 1.07%; Mo= 8 g/t; Ag = 14g/t Chalcocite, bornite,

molybdenite and

copper oxides

Filomena 35 km from

Taltal; 1200 m

altitude

Open pit 1.45 Mt copper oxides Average grade 0.95% Cu Atacamite, chrysocolla

and malachite

P.A. Moreno et al. / Minerals Engineering 24 (2011) 852858 853


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in Bond work index from 11 to 21 kW h/t. Oxide and sulphide ores

are stockpiled and treated separately. The general process flow

sheet of the Las Luces plant is shown in Fig. 2.

2.2. Flotation

The flotation circuit is comprised of 32 sulphide flotation cells

for Las Luces ore, 12 cells for Altamira oxides, thickeners and two

filter presses. The flotation plant has a rated capacity of 65,000 tons

per month. The flotation in the first two milling lines is carried out

in Outotec cells and the third one uses Denver cells. The circuit is

conventional consisting of traditional roughing, cleaning and scav-

enging operations.

The target Cu grade is 30% Cu and that for the Mo concentrate

45% Mo (with less than 3% Cu). The Ag in the concentrate varies

with ore type but can range from 751200 g/t Ag.

The flotation feed in terms of copper minerals is mostly chalco-

pyrite and chalcocite, with molybdenum mostly as molybdenite.

The flotation reagent suite varies with ore type but in general

the collectors used are sodium isobutyl xanthate (SIBX), AP 404,AP 3477 and MX 7013. The frother used includes methyl isobuthyl

carbinol (MIBC), Dow frother 250 and Dow frother 400. Diesel

(40 g/t) is added as a molybdenite promoter.

Recoveries and grades of the copper concentrate obtained vary

according to the origin of the mineral (see Table 3). When high

chalcocite ores are being processed, there are sometimes issues

with soluble copper and copper recoveries are lower, typically

7278% compared with more normal recoveries of 8290%. On

average the Cu recovery is about 84%.

The CuMo concentrates are treated in the molybdenum plant

to separate the Cu and Mo, using conventional sodium hydrogen

sulphide (NaHS) treatment and multiple cleaning stages. The Mo

recovery in the Mo plant is about 52%.

Concentrates from the cleaning steps are sent to the final stageof solidliquid separation by thickeners and filter presses, which

consist of two separate lines: the first concentrates for the first

two milling-flotation lines and a second for the third line. The final

product is thickened to 55% solids and then filtered. Filter cake

average moisture is under 10%. Concentrates are primarily treated

at the Paipote smelter.

2.3. Oxide plant

The copper oxide ores are leached in at the Oxide Plant located

50 km southeast from Taltal city. This plant has recently started

production to produce 5000 t/year of copper with a processing

capacity of 50,000 t/year of ore. The copper oxide ore is supplied

from the altered zones of Las Luces, Altamira, Doa Elba and

Filomena mines. In the Oxide Plant, the ore is crushed in closed cir-

cuit to a nominal size and agglomerated. In the Agglomeration

Plant, seawater and sulphuric acid are used to give the physical

chemical and moisture conditions required for the next stage of

the process, which is leaching with dilute sulphuric acid.

The leaching process is designed for 2.53.0 m high heaps at 20

to 60 day cycles. The leach solution is treated by solvent extractionand converted to metallic copper by electrowinning.

The seawater is used in agglomeration, leaching and converted

to higher purity water by reverse osmosis (RO). Seawater is

pumped to a collection pond in the Oxide Plant at a 44 km distance

through a pipeline. The RO water is used for the electrowinning

plant as this treatment needs high purity water. In electrowinning

the high purity water is used in washing the cathodes to remove

sulphation products. Some of this water is also used for human

consumption.

3. The use of seawater in Las Luces beneficiation plant

Las Luces underground mine development in northern Chile be-gan in 1994 and production started in 1995 with the construction

Table 2

Head and concentrate grades and recoveries at the Las Luces beneficiation plant (Source: Monardes and Bouso, 2009).

Ore Head grade Recovery (%) Concentrate grade

Cu (%) Ag (g/t) Au (g/t) Cu Ag Au Cu (%) Ag (g/t) Au (g/t)

Insoluble Soluble

Altamira 1.25 0.35 31 81 81 44 950

Las Luces 1.10 6 91 60 51 150

Tropezn 2.50 5 0.55 90 62 71 27 45 5.5Doa Elba 1.35 0.20 8.5 83 65 46 181

Table 3

Mineral phase analysis (XRD) of three major ore types for the Las Luces beneficiation plant.

Mineral Formula Altamira ore Las Luces ore Tropezn ore

Albite Na(AlSi3O8)p p p

Ankerite Ca(Fe+2,Mg)(CO3)2p

Calcite, syn CaCO3p p

Quartz, syn SiO2p p p

Chalcopyrite FeCuS2p

Clinochlore-1MIIb (Mg,Fe)6(Si,Al)4O10(OH)8p p p

Edenite NaCa2Mg5AlSi7O22(OH)2p

Hematite Fe2O3 p pIllite-2M1 (NR) (K,H3O)Al2Si3AlO10(OH)2p

Magnetite Fe3O4p p

Molybdenite-2H MoS2p

Muscovite-2M1 or 2M2 (K0.82Na0.18)(Fe0.03Al1.97)(AlSi3) O10(OH)2p

Pyrite, syn FeS1.74p

Siderite FeCO3p

Talc Mg3Si4O10(OH)2p

854 P.A. Moreno et al. / Minerals Engineering 24 (2011) 852858


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of the beneficiation plant and ancillary works in Las Luces. Theplant has used seawater as process water since 1995.

In the Las Luces plant, seawater is drawn at a rate of or approx-imately 44 L/s for 18 h per day from Punta Garcia beach near

Fig. 2. The flowsheet of Las Luces beneficiation plant and water sampling points.



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Taltal. Fig. 3 shows schematically the steps of pumping seawater to

the concentration plant in Las Luces. The first pumping from the

sea surface to the second pumping station covers a distance of

1425 m. The second pumping covering 3090 m and the third and

final pumping to the receiving tank of seawater into the concentra-

tor plant, covering 2450 m, represents a total pipeline length of

6965 m. The pipes are made out of high-density polypropylene

(HDPE) of 250 mm inner and 280 mm outer diameter (Monardes

and Bouso, 2009). To minimise the entry of solids into the pumps,

the pumps suck the water from a 43 m3 sump. These pumps work

in series and pump the seawater to the concentrator plant at alti-

tude of 178.1 m.

The KSB Megachem pumps are made of stainless steel internals

to withstand the high corrosion generated by the seawater. The

seawater suction pump and the pump in first pumping station

are type 80/200 and are driven by a 37 kW motor, while those in-

stalled in the second and third pumping stations are 65/200 type,

each driven by a 90 kW motor (Monardes and Bouso, 2009).

At the Las Luces plant, seawater is stored in a high density poly-

ethylene lined 2200 m3 capacity pond. The seawater, from the

Storage Pond is used in a variety of places (see Lines 25, 26, 44

in Fig. 2) and some (an average of 3.62 m3/day) is lost to evapora-

tion. This water, mixed with wastewater from the tailings dam, is

used in crushing, grinding and flotation operations in the plant.

The rest of the seawater (see Line 41 in Fig. 2) overflows to the

4000 m3 capacity Industrial Water Storage Pond at an average rate

of 2384m3/day. The volume of water used in each unit operation is

shown in Table 4. The daily intake of seawater to the plant is

2859 m3/day. Of this water 134 m3/day is used as seal water (Line

25), 299 m3/day as a dust suppressant for crushers (Line 44), and

30 m3/day as road irrigation water (Line 26).

The wastewater generated in the plant is stored in a tailings

dam which covers 130,062 m2 (or 13 ha) and has a water storage

capacity of approximately 190,000 m3. The recovery of surface

water from the tailings dam is achieved via a 2.5 m diameter col-

lection pond. This pond is interconnected by a pipe, located below

the floor level of the dam, to the Industrial Storage Pond.The daily water balances for the water holding ponds are shown

in Table 5.

The storage pond supplies process water to 3 grinding mills at

an average rate of 6250 m3/day via Line 27 in Fig. 2. This water is

used in grinding and flotation circuits and recycled back to the tail-

ings dam. In the tailings dam on average 650 m3/day of the re-

ceived water is lost to evaporation each month. The overall

evaporation losses are 660.5 m3/day when evaporation from other

ponds (Industrial Storage and Seawater Storage ponds) is taken

into account. The wastewater comes to the tailings dam in a slurry

form and is dewateredby set of cyclones. The slurry containing fine

and coarse gangue minerals is discharged into the Dam at an aver-

age rate of 6250 m3/day via Line 37. From the Dam, clear water is

pumped to the Storage Pond at an average rate of 3684 m3/day

(Line 39) and mixed there with seawater at a rate of 2384 m3/day

(Line 41). It is estimated that on average 2565 m3/day water is lost

to evaporation, accidental overflows, spills, and pulp impregnation

in Line 38. The evaporation rate at the mill site is on average

around 50 m3/hectare/day. The high evaporation rate is due to

the fact that the operation is located in an extremely arid area.

The Taltal region is known to have a mean precipitation (rain

and snow) of only 6.7 mm/year (Environmental impact statement,

2007).

Sea Wateruptake

Elev: 0 mDist: 0 m

Pump Station 1Elev: 15.7 mDist: 1,450 m

Pump Station 2Elev: 95.2 mDist: 4,540 m

Storage PondElev: 178.1 mDist: 6,990 m

Fig. 3. Seawater uptake to the Las Luces process plant.

Table 4

Daily volumes (m3/d) of water used in each unit operation.

Flows heet line No.

(Fig. 2)

Description m3/day

1 Plant feed 56

2 Material handling 175

3 Material handling 175

4 Storing line No. 1 75

5 Storing line No. 2 756 Storing line No. 3 24

7 Grinding line No. 1 75



10 Collective flotation line No. 1 2719

11 Collective flotation line No. 2 2687

12 Collective flotation line No 3 864

13 Concentrate. line No. 1 90

14 Concentrate. line No 2 74

15 Concentrate. line No. 3 37

16 Feed filter plant 37

18 Concentrate lines 1, 2 & 3 5

20 Thickener 1 overflow 164

22 Filtered water 1 31

24 Recycled process water 194

25 Seal water 134

26 Road irrigation water 3027 Plant process water 6250

28 Grinding feed water line No. 1 2644



31 Flotation feed water line No. 1 47



34 Flotation tailings line No. 1 2677



37 Tailings dam feed 6250

38 Tailings dam total losses 2566

39 Recycled water from tailing dam 3684

40 Ind. water stage. pond losses 12

41 Seawater overflow to industrial water pond 2384

42 Seawater storage pond losses 12

43 Seawater from sea uptake 2859

44 Water used for dust suppress. 299

45 Tailings pumping station losses 110



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Table 5 summarises the water recycling at the Las Luces plant.

The amount of water coming to the Industrial Storage Pond

(6262 m3/day) is the same as the amount of water leaving the

Pond. Similarly, the water, coming in and going out, balances well

for tailings dam and tailings dam pump station.

4. Variation in the salt content over time

The variation of the major elemental content of the seawater

was investigated using two seawater samples, one from Taltalbeach and the other from the seawater Pond at the mill site, and

exit water from Industrial Storage Pond (Line 27). The water anal-

yses were performed by using atomic absorption, titration (for Cl)

and gravimetric (for SO4) methods. The chemical analyses are

shown in Table 6. The variation of 0.9% in the composition of sea-

water between the intake and outlet points is related to sampling

and analytical errors.

In the Las Luces plant, the grinding and flotation cells are fed

from the Industrial Storage Pond which contains 46.4 g/L total dis-

solved salt. This indicates that the total dissolved salt content of

seawater has increased by about 10.4 g/L as a result of continuous

seawater recycling during last 15 years. This amount, on average,

represents an approximately 0.73 g/L increase per year assuming

plant operation conditions remained unchanged throughout this

time.

The increase as a result of solar evaporation can be estimated

from a dissolved salt mass balance calculation on seawater based

on the data given in Table 7:

SWvolIN SWcIN SWvolIN EvapSWcOUT 1

or

SWcOUT SWvolINSWcIN

SWvolIN Evap2

where SW= seawater; vol = volume and c= concentration

36:04g

L

2859 m3

day

2859 m3

day 660:52 m

3

day

46:9gL

3

This value will remain the same in any time period as long as the

seawater intake volume and evaporation rate remain unchanged.

The calculated total dissolved salt value, 46.9 g/L, is very close

to the measured value (46.4 g/L) in the Industrial Storage Pond.

This indicates the increase in the total salt content in time is largely

the result of evaporation.

5. Combating corrosion in Las Luces

In Las Luces, all the facilities are permanently exposed to the

corrosive action of salt water. The damage on the metal surfaces

is minimised by taking the following precautions:

(a) The effects of corrosion on the surface of steel plates is min-

imised by painting, applying vulcanized rubber coating and

spray coating with polyurethane.

(b) The pipes and pipe components used in concentrator plant

are rubber-coated steel or made out of high density polyeth-

ylene. All the valves and pumps are made out of A 743 or A

316 type stainless steel. Experience shows that A 304 stain-

less steel is not suitable.

(c) Intake and seawater pumping stations are cleaned every

90 days to avoid fungi and barnacle growth, which can resultin pipe blockage.

(d) The pumps are inspected every 4000 h. The impellers of the

pumps are changed every six months and the pumps every

year.

Table 5

Water usage (in various parts of the plant) and its balance in the Las Luces

beneficiation plant in June 2009.

IN OUT

Seawater circuit

Line No.

Volume IN

(kL/d)

Seawater circuit

Line No

Volume OUT

(kL/d)

43 2859 42 12

26 30

44 299

41 2384

25 134

SUM (IN) 2859 SUM (OUT) 2859

Industrial Storage

Pond

Volume IN

(kL/d)

Volume OUT

(kL/d)

39 3684 40 12

41 2384 27 6250

24 194

SUM (IN) 6262 SUM (OUT) 6262

Tailings Pumping

Station

Volume IN

(kL/d)

Tailings Pumping

Station

Volume OUT

(kL/d)

25 134 37 6250

34 2677 45 110

35 266236 887

SUM (IN) 6360 SUM (OUT) 6360

Tailings dam Volume IN

(kL/d)

Tailings dam Volume OUT

(kL/d)

37 6250 38 2566

39 3684

SUM (IN) 6250 SUM (OUT) 6250

Table 6

ICP analysis (g/L) of seawater and Storage Pond exit water samples.

Sample Na K Ca Mg Cl SO4 SUM

Line 27 13.3 0.4 1.4 1.79 24.6 4.88 46.37Line 43 Seawater 11.1 0.38 0.39 1.38 19.8 2.83 35.88

Seawater Taltal 11.4 0.38 0.39 1.39 19.8 2.84 36.20

Table 7

Calculated evaporation loss from major ponds based on mean daily evaporation rate of 0.05 m3/m2/day.

Volume (m3) Area (m2) Evaporation loss (m3/day) Evaporation contribution (%)

Tailing dam 190,000 130,062 650.3 98.45%

Industrial pond 4000 1,317 6.6 1.00%

Seawater pond 2,200 724 3.6 0.55%

Tailings pump station negligible negligible

Total 196,200 132,103 660.5 100.00%



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The money spent for the maintenance of metal surfaces and

replacement of pumps is an important part of the operating costs

in the Las Luces plant relating to the use of seawater.

There are of course a number of advantages and disadvantages

in using seawater exclusively at the mine. For example, there is no

acquisition cost for seawater and it is an inexhaustible natural

resource. In the absence of any fresh water in the close vicinity,

seawater is the only water available for the Las Luces plant. Fur-thermore, the use of seawater would protect the existing fresh

water reserves stored in subsurface aquifers and glaciers.

Although there is no acquisition cost for seawater, the opera-

tional and capital investment costs of using seawater could be

higher than that of fresh water. This is largely due to the expenses

needed to combat the corrosive effect of seawater, and the con-

struction and maintenance of the pipeline to transport the seawa-

ter to the plant site.

6. Conclusions

The Las Luces plant is a good example of continuous use of sea-

water at a minerals beneficiation plant without the need for fresh

water. The operational records show that metallurgical results arenot affected by the salinity of the seawater. The data show that

during last 15 years the increase in the total dissolved solids con-

tent of the process water was small, from approximately 36.0 g/L

(seawater) to 46.4 g/L. The mass balance calculations show that

the 10.4 g/L increase is largely related to the solar evaporation

where the rate reaches 50 m3/hectare/day.

In Las Luces, the annual evaporation related water losses

amount to 237 megalitres or a loss of approximately 69 days of

seawater pumping to the Storage Pond. Based on this finding Las

Cenizas is now investigating options to minimise the loss of water

to evaporation.

The recent lab-scale work of Aral et al., 2010 to compare the

performance of copper rougher flotation in distilled water (Spe-

cific Gravity SG = 1.00), seawater (SG = 1.025) and hypersaline

(SG = 1.23) water gave similar copper recoveries for distilled

water and seawater flotation, approximately 78%. However, a

significant deterioration in copper recoveries was observed when

hypersaline water was used. As well the copper grades of con-

centrates from the distilled and seawater were also comparable

(about 20%). Their data suggested that there is probably a total

dissolved salt content limit for the water used in copper

flotation.

The option of using seawater for mineral processing instead of

freshwater, promises to be an interesting alternative for exploita-

tion of many mineral deposits not only for Chile and Peru but also

for countries such as Argentina, Brazil, Australia, Philippines, New

Guinea, Angola, Namibia, northwest Africa, South Africa and even

for the countries located in semi-arid and temperate climatic zones

in the Northern Hemisphere.

Acknowledgements

This work was funded by the Centre of Energy and Sustainable

Development (CESD) of Diego Portales University (Santiago, Chile)

and Sustainable Processing Theme of CSIROs MDU National Flag-

ship Projects. We acknowledge Prof. Dr Jos Robles Dean of Engi-

neering, Dr. Edmundo Claro, Director of the CESD for providing

funds for the field trip and sample analysis. We thank Prof. Dr Luis

A. Cisternas of CICITEM for providing access to the chemical anal-

ysis of the liquid samples which were performed at the Universityof Antofagasta.

References

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