Novel methods for metal collection combined to online detection
Lasse Moilanen1, Risto Oikari2, Jarkko Räty3, Kimmo Kemppainen2, Tero Luukkonen2 and Jouko Vepsäläinen4
1Oy
Chemec Ab, Ahventie 4 A21-22, 20170 Espoo, Finland, 2Kajaani University of Applied Sciences, P.O.Box 52, FI-87101 Kajaani, Finland, 3University of Oulu, Tekonologiapuisto P.O. Box 127, FIN-87400 Kajaani,
Finland, 4School of Pharmacy, University of Eastern Finland, P.O.Box 1627, FIN-70211 Kuopio, Finland
Introduction
Geopolymers
Biopolymers and SO4 removal
In 2010 the European Commission estimated that at least 14 industrial
raw materials, e.g. Sb, Co, REE, are critical to the functionality of the
Union's industrial activities e.g. due the limited availability. The high
requirement of REEs presents a major challenge to the mining industry
since only few economically viable REE deposits are available.
Geopolymers (GP), developed by Kajaani University of Applied
Sciences (KUAS), are novel, green and low-cost cation exchangers
prepared,
for
instance,
from
industrial
side-products.
Geopolymerization improves significantly the sorption capacity of raw
materials. GPs can be regenerated and thus are potential sorbents for
metal recovery from various wastewaters and effluents.
Recently, we have developed and patented in UEF a
novel method to remove sulfate (SO42-) from aqueous
solution based on a solid biopolymer. The developed
method is able to reduce SO42- concentration of an
aqueous medium below 50 mg/l when the starting
SO42- concentration is <1000 mg/l, and <500 mg/l,
when the starting sulfate concentration of the
aqueous medium is 2000 to 3000 mg/l. These levels
are much lower than what can be reached with most
known sulfate removal methods.
Univ. Eastern Finland (UEF) developed a novel resin-free ion exchanger (CH
Collector, commercialized by Chemec Oy) to collect metal ions from
aqueous solutions. Material is non-toxic and regenerable over number of
cycles, and cost effective compared to other ion exchange materials.
Water Treatment & metal recovery applications
Raw materials =
Pb
Organic
Industrial by-products or
low-cost natural minerals
including:
• Kaolinite / metakaolin
• Blast furnace slag
• Fly ash
• Paper mill fiber sludge
pollutants
NH4+
Municipal
wastewaters
Crystal structure of CH Collector
Co
Cd
Ni
Industrial
effluents
As
Sb
Mining
effluents
Geopolymers
Electron microscope
picture of CH Collector
CH Collector enables selective collection of metal ions, e.g. Pb, Sb, Y, Th
and Sc, since collection is temperature, pH and counter cation (during
regeration step) dependent. Depending on the metal cation CH Collector
has four (I-IV) different types of pH behavior: I) ions are collected before
(e.g. Ir3+) or II) after (e.g. Ag+, Cu2+, Ni2+) a pH value, III) ions are collected in
a certain pH value (Al3+) and IV) ions are collected independing of pH value
(e.g. Sc3+, Sb3+ and UO22+)
Landfill
leachate
Zn
Processing
•
•
Mild reaction conditions
Simple process: e.g.
granulation
Depending on metal CH Collector has
four different types collection behaviour
CH Collector enables either
simultaneous collection of a group
different metal ions (e.g. pH = 7)
or selective stepwise collection in
fixed pH values. For example, Sb is
selective collected when pH <0.5,
Ag pH = 1, Cu = 3 and Ni > 5.
pH dependency of Sb, Ag, Cu and Ni cations.
On-line measurement of Ni, Pb and SO42-
Step 1
CH Collector at 5°C
On-line detection
Pb2+
Water containing Ag, Ni and SO42On-line measurement of Ni and SO42-
On-line detection
CEMIS-Oulu has developed a novel approach to measure trace
concentration of toxic metals (Cu, Ni, Pb, and Hg) down to the ppblevel in real time from aqueous solutions. The method is based on an
innovative Hg-free nano-scale electro-chemical sensor passing also
heavy field tests..
Only Pb2+ is collected at low temperatures
Possible purification process
Water containing Ag, Ni, Pb, Sb and SO42-
Ion chanel
CH Collector,
n = 10
Cu
Step 2
CH Collector pH < 0
Sb3+
Water containing Ag, Ni and SO42On-line measurement of Ni and SO42-
Step 3
CH Collector pH = 2
Ag+
Water containing Ni and SO42On-line measurement of Ni and SO42-
Step 4
Step 5
Geopolymer
On-line detection
Biopolymer
On-line detection
Pure water
Ni2+
SO42-
Selective metal collection and CH Collector regeneration
CH Collector