RemedRemediationiation onon the formerthe formeruranium mininguranium mining andand millingmilling sitesite

(Hungary)(Hungary): Case Study: Case Study

M. CsővariThe presented work is a common

work of the experts fromMECSEK-ÖKO Rt, Pécs, Hungary

andMECSEKÉRC Rt, Pécs, Hungaryand other companies, institutions

„DIFPOLMINE” CONFERENCE Budapest4-8 July 2005

Location of the site

The site has a close connection withdrinking water catchement areas

(T and P).

T P

Water treatment is neccessary for:Mine water

Contaminated groundwater

Geological crossGeological cross--section of thesection of theformer mining siteformer mining site(Western(Western MecsekMecsek))

±0

-700

SandstoneClaystone

P-T Sandstone

Tectonic zoneUranium ore

Legend

Anhydirte Siltstoneaquitard

Limestone M Sand and clay

Pl Loose sand (aquifer)2

Northern shaftsSouthern shaft

Adit

D

D- drinking water aquifer

Anticline

Water treatment processesWater treatment processes

1) Mine water treatmentAnion-exchange process is used for U(TDS~1.6 g/l; U~5 mg/l; As<12 mg/l, Ra~0.3 Bq/l)

2) Groundwater treatmentPump and treat process

(TDS~3-15 g/l; U<0.1 mg/l; Ra~0.08 Bq/l)Heavy metals:As<12 mg/l;

Pilot-scale PRB (ZVI + sand mixture)(in situ groundwater treatment, experiment)

I Mine water treatment stationI Mine water treatment station

Station is situated on the area of former Shaft NI

Mine water

As

Yellow cake productionYellow cake production

B

Packing unit

U-concentrate accretion onthe mixer in dryer causes

some problemsPrecipitation of

uranium peroxide

Mine water treatmentMine water treatmentSorption efficiency for uraniumSorption efficiency for uranium

0

2

4

6

8

10

12

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004Ye ar

U, m

g/l U in mine water.

U effl.

Ueff l.~0.2 mg/l

U~2 t/aExtra water fromremediation activityof HL

U~7 t/a

V~0.44 Mm3/aV~1.2 Mm3/a

The change of uraniumThe change of uraniumconcentration in mine waterconcentration in mine waterover long period (1968over long period (1968--2005)2005)

0

2

4

6

8

10

12

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

Year

U, m

g/l

Volume and concentration were affectedby heap leaching

6-7 mg/l 4.5-5 mg/l35 years

Mill

TP

Pipeline TPI

TPII

II Groundwater treatmentII Groundwater treatmentTailings PondsTailings Ponds

Total volume of the tailings:20.4 kt solid + 32 Mm3 of liquid

Groundwater restorationGroundwater restoration

577000 577500 578000 578500 579000 579500 580000 58050075000

75500

76000

76500

77000

77500

78000

78500

79000

A-01

B-01

C-01

H/1

U-09/1

U-10/1

U-11/1U-13/1

U-14/1

U-16/1

U-17/1

U-18/1

U-19/1

U-20/1

U-21/1

V-01/1

V-02/1

V-03/1

V-05/1

V-07/1

V-08/1

V-10/1

V-11/1

V-13/1

V-14/1

V-15/1

V-16/1

V-17/1

V-18/1

V-19/1

V-20/1

V-21/1

V-22/1V-23/1

V-24/1

V-25/1

V-26/1

V-27/1

V-28/1

V-29/1

V-30/1

V-32/1

V-33/1

V-35/1

V-36/1

V-37/1

V-38/1

V-39/1

V-41/1

VIII/1

X/1

XIII/1

XVIII/1

XXVII/1

Bicsérd-2/F-5

Pellérd-1/F-5

ZA-1

ZB-1

ZC-1

ZE-1

ZG-1 ZH-1

ZI-1

ZB

ZC

ZD

ZF

ZIZJ

R-11

R-12

R-15

R-16

TDS (mg/l) in the shallow groundwateraround the tailing ponds in 2003

1000 4000 8000 12000 16000 20000

0 500 1000 1500 2000

577000 577500 578000 578500 579000 579500 580000 58050075000

75500

76000

76500

77000

77500

78000

78500

79000

A-02

B-02

C-02

G

H

U-09

U-10

U-11 U-12 U-13

U-15

U-16

U-17

U-18

U-21

U-22

U-23

V-01

V-03

V-05

V-07

V-09

V-12

V-13

V-14

V-15

V-17

V-21

V-22V-23

V-24

V-25

V-26

V-27V-29

V-34

V-36

V-37

V-38

V-40

VII

XIIIBicsérd-2/F-3

Pellérd-1/F-3

ZA-2

ZB-2

ZC-2

ZD-2

ZE-2

ZF-2

ZG-2

TDS (mg/l) in the deeper groundwateraround the tailing ponds in 2003

1000 4000 8000 12000 16000 20000

0 500 1000 1500 2000

5-20 m25-40 m

TPI

TPII

18 g/l 4 g/l

S hallow GW5-20 m

Deeper GW25-40 m

TDS

GW contamination

GroundwaterGroundwatercontamination undercontamination under thethe TPTP

25 m10 m

TDS in pore water

-40-35-30-25-20-15-10-50

0 5000 10000 15000 20000 25000 30000TDS, mg/l

Dep

th, m

577000 577500 578000 578500 579000 579500 580000 58050075000

75500

76000

76500

77000

77500

78000

78500

79000

A-01

B-01

C-01

H/1

U-09/1

U-10/1

U-11/1U-13/1

U-14/1

U-16/1

U-17/1

U-18/1

U-19/1

U-20/1

U-21/1

V-01/1

V-02/1

V-03/1

V-05/1

V-07/1

V-08/1

V-10/1

V-11/1

V-13/1

V-14/1

V-15/1

V-16/1

V-17/1

V-18/1

V-19/1

V-20/1

V-21/1

V-22/1V-23/1

V-24/1

V-25/1

V-26/1

V-27/1

V-28/1

V-29/1

V-30/1

V-32/1

V-33/1

V-35/1

V-36/1

V-37/1

V-38/1

V-39/1

V-41/1

VII I/1

X/1

XI II /1

XVI II /1

XXVII /1

Bicsérd-2/F-5

Pellérd-1/F-5

ZA-1

ZB-1

ZC-1

ZE-1

ZG-1 ZH-1

ZI-1

ZB

ZC

ZD

ZF

ZIZJ

R-11

R-12

R-15

R-16

1000 4000 8000 12000 16000 20000

0 500 1000 1500 2000

GroundwaterGroundwatertreatment processtreatment process

Treatment process consist of:• Precipitation of magnesium and

gypsum with calcium hydroxide•Sedimentation and thickening•Filtration

Shallow GW: TDS~10-12 g/lFor treatment

Deeper GW : TDS~3-5 g/lDirect discharge

Groundwater extractionGroundwater extractionsystemsystem

WT

Drainage: 2.8 kmWells: 15+12

Q~0.5 Mm3/a0.3 Mm3/a

Sludge from treatmentSludge from treatment

Mg~17%Ca~17%SO4~26%U~60-70 g/tRa~24 Bq/kg

Sludge7kt/a (with 50% water content)

Treated water:~0.36 Mm3/a

TDS~6-7 g/l (retention time!!)(NaCl~3 g/l)

Gypsum accretion onGypsum accretion onthe surfthe surfaacece of technological equipmentof technological equipment

Critical parts and units must bemonthly cleaned from

gypsum accretion

WaterWater discharge summarydischarge summary

Treated groundwater Treated mine water

Mixing basinTDS:3.2 g/lU:0.2 mg/l

Ra:0.18 Bq/l

Receiver

Data for 2004

Non-treatedwater

(e.g.deeper GW)V:1.27 Mm3

V:0.36 Mm3 V:0.44 Mm3

IIIIII PilotPilot--scale PRBscale PRB(for in situ treatment of GW)(for in situ treatment of GW)

Field test aiming at investigating of long-term performanceof PRB (EU project: EVKI-1999-00035) for removing

of U from GW

Practical solutions are known in first of all inUSA ,but the long-term performance is stillunder investigation

For field test ZVI+sand mixture was selected, thoughdifferent reactive materials were tested in laboratory

and in columns on the field

Permeable reactive barriersPermeable reactive barriers

Permeable reactive barriersPermeable reactive barriers

Funel anf gate systemFunel anf gate system

Uranium contaminated groundwaterUranium contaminated groundwaterIn valleyIn valley ZsidZsid

Valley

Valley Zsid

Monitoring well Hb1/1

Slite contamination of GW was detected in GW on the site

Laboratory experiments in columnsLaboratory experiments in columns

Iron, hydroxiapatite,anion exhange resin,

etc. were tested

Removal of uranium fromRemoval of uranium fromcontaminatedcontaminated GWGW

Uranium can be is removed from GW by steel fibres

0

100

200

300

400

500

600

700

800

900

1000

0 64 74 85 96 106

117

127

137

Sample number

U, µµ µµg

/lFeedHb1/1

Effluent

Changing the general chemistry ofChanging the general chemistry ofwaterwater

Bycarbonate calcium etc. Are dropps during treatment

0

100

200

300

400

500

600

700

54 64 91 100 109 118 127 136

Sample number

kcon

cent

ratio

n, m

g/l

Ca

Mg

HCO3

FeedHb1/1

Colomns inColomns in monitoringmonitoring wellswells

2,3m

6,3m

Plasticpipe Ditch

∆∆∆∆H

Colomn F=8-12cm2 , L=1-1,4 m

drain

Field column experimentsField column experiments

Geochemical processes controllingGeochemical processes controllingGWGW chemistrychemistry

[Fe][CO3] = 2,50E-11 200C

[Fe][OH]2 = 1,64E-14 180C

H2CO3 = HCO3- + H+

K=10-6,3

HCO3-=CO32- + H+ K=10-10,25

[Ca2+] [CO32-]=1.20E-08 200C

Geochemical processes inGeochemical processes inGWGW

Iron concentration vs. pH

0

10

20

30

40

50

7 7.5 8 8.5pH

Fe, m

g/l Fe2+ CO3

2-=FeCO3

Location of the PRBLocation of the PRB

The installation is locatedin a narrow valley atthe foot of WPIII, linkingthe mining area withdrinking water aquifer(Zsid-valley)

WP3

GW flowdirection

PRB

Valley

Principal designPrincipal design of theof theexperimentalexperimental PRBPRB

Soil 50 cmUp stream

Down stream

2.5 m6.8 m

3.8 m

Comp. clay30 cm

HDPE

Bedrock

Bentofix

A

B

Cross-section A-B

Legend: Sand

0.39 t/m3 iron (1-3 mm, 5 t) with sand

1.28 t/m3 iron (0.2-2 mm, 33 t) with sand

Mon. wells

Elemental iron mixed with sand

Spec. Surface:0.7 m2/g

0.2-3 mm

Construction of the PRBConstruction of the PRB

Permian sandstone withsediments

Two layers ofFe+sand mixture

Monitoring wells placed inreactive zones

Construction of the PRB

course ZVI + sandZVI + sandsandclay

HDPE

Bentofix

aquiferspiezometric head

Design of experimental Permeable Reactive Barrier

GW flow

Length:6.8 m;Depth:3.9 mWidth: 1.5m;Two zones;G:39 t ZVI (mixedwith sand)

PRB with monitoring wells

28 monitoringwells

Precipitation of uraniumPrecipitation of uraniumand dissolution of ironand dissolution of iron

Uranium concentratio n pro file in the PRB

1

10

100

1000

-50 0 50 100 150 200width, cm

U, µµ µµ

g/l

Iron concentration profile in the PRB

0

5

10

15

20

25

-50 0 50 100 150 200

Uranium conc. drops inthe first zone

Iron first dissolvesin first zone

than precipitatesin the 2nd zone

Concentration profiles in zones of PRB

Concentration profiles in PRB

0

20

40

60

80

100

120

0 0,5 1 1,5 2width of PRB, m

%fr

om in

flow

Ca

Mg

TDS

SO4

HCO3

Spec. cond.

Fe~20 mg/l

TDS

U

PRB performancePRB performance(August 2002(August 2002--April 2005)April 2005)

Uranium is removed with high efficiency but huge volumeof inert compounds (CaCO3, MgCO3 etc.) is precipitated

EC U(VI) TDS Ca SO4 HCO3 FeµS/cm µg/l mg/l

Inflow 6.9 1400 940 1010 150 320525 0.002ZoneI 7.3 1330 37 937 125 300275 5.5

ZoneII 8.7 865 10 550 10 185299 0.03

pHGW flow direction

Isolines of uranium and calciumIsolines of uranium and calciumconcentrations on the test fieldconcentrations on the test field

U Ca

V.7 Development of uraniumV.7 Development of uraniumconcentration in downstreamconcentration in downstream

monitoring wellmonitoring wellUranium concentration in groundwater after

construction of the PRB

0

200

400

600

800

1000

1200

13.03

.9605

.02.97

06.10

.9714

.05.98

26.03

.9920

.06.00

11.01

.0124

.01.02

15.04

.0228

.11.02

22.01

.0304

.06.03

date

U, µµ µµ

g/l

Const.of PRB

monitoring well:Hb1/1

Performance change

Water passed through the PRB: ~700 m3/aFormed precipitate: ~0.5 kg/m3~ 350 kg/aFree porosity in PRB (original) ~11 m3

Annual losses:~ 0.35x2.7~0.094 m3

in persentage:~1-1.5%

Iron dissolution:~20-30 mg/l Fe(II)G=~700x0.03=21 kg/a

Performance monitoring is continued•by regular water sampling•by planned drillings•by hydrogeological evaluation

Acknoledgement

The research works related to the GWtreatment was

suported by the IAEA (Contract: N0 9114).

The research related to the PRB and dispersionof contaminants under TPs was partially suppotred

by EU(Contract: EVIKI-1999-00186 andEVGI-CT-2002-00035)

Precipitation of gypsum andmagnesium

Kinetic curves o f the prec ipitatio n o fmag nes ium hydro xide and gyps um

0

0.5

1

1.5

2

2.5

0 1 2 3 4

time , hours

conc

entr

atio

n, g

/l

Ca

Mg

I.I.33 ProjectProject cost distributioncost distribution

A Beruházási Program létesítményi sorainak költségeloszlásdiagramja

13%

8%

4%

11%

40%

6%

1%

1%

3%9%

5%

Földalatti létesítmények felhagyása Külszíni létesítmények és területek rek.Meddőhányók és környezetük rek. Perkolációs dombok és környezetük rek.Zagytározók és környezetük rek. Bányavíz kezelésVillamos energia hálózat rekonstrukciója Víz- és csatornahálózat rekonstrukciójaEgyéb infrastrukturális szolgáltatás Egyéb tevékenységTartalék az 1998-2003. éves összegre

TPs

Mines

HLMWT

RoadsRes.fund