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Isolating Plants Completely from Natural Water Systems
AiChE
Industrial Water Use and Reuse Workshop
Kari Heiskanen, D.Sc.
Oct. 25 2016
© Outotec – All rights reserved
Outline • Introduction
• Water system in terms of quality
• Tests on mineral dissolution
• Technology solutions
• Challenges
• Tools and dreams
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Introduction
• Rethinking and reinventing the role of
water • The most important solvent and dispersion agent
• Enabling effective use of resources
• We need to take care of its properties and optimize
these properties for each process step
• The traditional role of water • A cost item
• An issue in social license of operation
• We need to clean it at lowest possible cost
• We need to enhance the recycling of it
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Introduction Effects of closing the loops In
cre
asin
g p
rocess d
istu
rba
nce
NEW Water Reuse Concepts
closed open
feasibility limit of
existing solutions
Fresh Water Usage
Fines (colloids...)
Cations Fe, As, Ni, Cu,
Ca, Mg ...
Anions: S- species,
Nitrogen, phosp.
Residual reagents and
their diss. prods.
Organics; humic, ...
Biological activity
Etc...
uS
Eh
pH
C °
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Water system boundaries (quality)
MWT= Mine Water Treatment
RWT= Raw Water Treatment
ETP = Effluent Treatment Plant
Reagents Dissolved sp.
fines
Dissolved sp.
colloidal
Dissolved sp.
colloidal
Thermodynamics
and kinetics Annual changes
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Water quality effectors
•From make-up water • Organic substances, Fe, Mg...., colloidal solids, bacteria etc
•From mine drainage • Nitrogen compounds, Fe2+, Mg... Cl-, oils, organic s. Bact. Salinity, pH
•From grinding and flotation • Dissolution from ore and gangue minerals, fine solids, reagents
• Bulk Reactions (thermodynamics, kinetics)!!
• Surface reactions (thermodynamics, kinetics)
•All this will depend on 1. the mineralogy suite!
2. The techno-economic goals of the plant!
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
One of the difficult separations is chalcopyrite-pentlandite-pyrrhotite
a1: Fe4,5Ni4,5S8 to (FeS)(NiS)
a2: formation of Me(OH)xS2
a3: oxidation of sulphur species
c1: Ni(OH)x reduction
c2: Fe(III)(OH)x reduction
c3: S0 reduction to S22-
c4:S22- reduction to S2-/ Fe2+ reduction
Fe
4,5Ni
4,5S
8=(Fe
4,5-xNi
4,5-xS
8)+ xFe2+ + xNi2+ +4xe
Fe
4,5Ni
4,5S
8+Ca2+ =(Fe
4,5-xNi
4,5-xCa
adsS
8)+ xFe2+ + xNi2+ + 4x -2( )e
Chalcopyrite: Chemisorption of Xanthate to
surfaces, partial oxidation to dixanthogen
Pentlandite: chemisorption takes place on
nickel sites; then oxidized on the surface to
dixanthogen
Pyrrhotite: physical adsorption of dixanthogen
formed in pyrrhotite oxidation process
Calcium is often used to control the pH to
depress Pentlandite and pyrrhotite.
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Mineralogy / ore type <=> water quality
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
An operational Cu-Ni deposit CuFeS2; (Fe,Ni)9S8; Fe0,94S, hornblende, serpentine
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Test site: Water assays
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Test site Different water qualities over a year
Raw
water
A
Process
water
B
Cu
Thick. OF
C
Cu
Thick. OF
D
Sept 2014 Jan 2015 March
2015
June 2015
Mg mg/l 1.52 1.51 1.65 1.32
Na mg/l <5 1.4 5 1.3
uS 59.5 34.3 59.2 76
pH 8.26 6.63 6.92 6.56
Aero. Bac 7 600 10 000 500 -
Sept 2014 Jan 2015 March
2015
June 2015
Mg mg/l 36.8 35.8 32.5 41.2
Na mg/l 114 248 278 97
uS 1390 1960 2140 1237
pH 7.67 6.53 7.26 5.94
Aero. Bac 48 000 160 000 2 000 000 -
Process water Raw water
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Xanthate; theoretically !
Hydrosulphide (HS-) and trithiocarbonate (CS3-2) have
known negative effect on flotation Dautzenberg et al 1969
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Testing of mineral dissolution 1
ORP= on-line Eh Ag/AgCl reference
Grinding long times in a steel lined ball mill
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Testing of mineral dissolution 2
0
50
100
150
200
250
300
0 20 40 60 80 100 120
Conductivity (
uS
/cm
)
Minutes of grinding time
Conductivity River Water
RW1
RW2
RW3
0
50
100
150
200
250
300
350
0 20 40 60 80 100 120
Conductivity
(uS
/cm
)
Minutes of grinding time
Conductivity Tap Water
TW1
TW2
TW3
Conductivity of water
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Testing of mineral dissolution 3
-50
-40
-30
-20
-10
0
10
20
30
40
50
Pure Water Tap Water River Water Thickener Overflow Tailings Pond Pure Water, pH 9mg
/L
Change in calcium concentration
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Testing of mineral dissolution 4
0
10
20
30
40
50
60
70
80
Pure Water Tap Water River Water Thickener Overflow Tailings Pond Pure Water, pH 9
mg
/L
Change in magnesium concentration
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Testing of mineral dissolution 5
0
10
20
30
40
50
60
0 20 40 60 80 100 120 140
mg
/L
Minutes of Grinding
Sulphur
Pure Water
Tap Water
River Water
Pure, pH 9
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Testing of mineral dissolution 6
•Water from the tailings pond
0
20
40
60
80
100
120
140
160
180
0 20 40 60 80 100 120 140
mg
/L
Minutes of Grinding
Tailings Pond
Ca
Mg
Na
K
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Needs of cleaning
•The results show some possibilities for two
strategies
1.Cleaning of a small side-flow to control the
overall quality of water to a suitable level - The cleaning need can be well below 10% of the
total water flow - Small modular units
- Several technologies available on the market
2. Use some technologies by designing to
partial operation
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Needs of cleaning
•Both alternatives need advanced
measurement technologies
•Both alternatives need very advanced feed
forward type of model/data based
advanced control
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Suggestion of new water circulation; divide it into two
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Modelling
Joining Outotec HSC SIM Aqua model (water
thermodynamics+kinetics)+ HSC Min model
(mineralogy)+ multilevel Matlab Simulink modelling
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Challenges
1. Ore type characterization for water model => model
based water control
2. Robust water quality sensors
3. Combine traditional water chemistry to mineralogy into
complex water models (generic engine+local tuning)
4. Ways of controlling the pH-Eh regime in a large scale?
5. Dry tailings unit cost
6. Control dry tailings deposit stability and dusting
7. Oxygen diffusion and water percolation into tailings
8. Site design
9. Etc...
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Tools
Outotec EWT-40 module As removal at Codelco
DAF
Polishing filters 25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
Tools: Water quantity and quality mgmt
Holistic solution for monitoring and
managing data on the mine site’s
water balance and water quality
• Wireless online monitoring stations, sensors, secure
data management, software applications, reporting
portal and services
Modular and scalable service
• Real-time information of process and natural waters
to a single database with KPIs for different
stakeholders in the plant
• Dynamic water balance and quality information,
short term forecasts for operational conditions
• Evaluation tool for process changes, water treatment
options and expansion projects
• Services to support the solution
+ Rain/snow
+ Surface runoff
+ Ground water
- Evaporation - Seepage
- Infiltration
WQQM Operating Environment
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen
© Outotec – All rights reserved
The dream
25/10/16 AIChE Water Seminar; Denver CO; 2016/ Kari Heiskanen