Remediation of Cretaceous Sediments affected by uranium in-situ leaching (ISL) in the Czech Republic

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1 NATO SPS Study "Prevention and Remediation Issues in Selected Industrial Sectors " Ljubljana, July 2007 RNDr. Josef Tomas Remediation of Cretaceous Sediments affected by uranium in-situ leaching (ISL) in the Czech Republic MINISTRY OF ENVIRONMENT, CZECH REPUBLIC Prague

2 NATO SPS Study "Prevention and Remediation Issues in Selected Industrial Sectors " Ljubljana, July 2007 Geological map of the Czech Republic Scale 1 : MINISTRY OF ENVIRONMENT, CZECH REPUBLIC Prague 2007

3 remediation area Orientation map Praha CHOPAV Brno N TLUSTEC BLOCK shaft no. 3 Hamr n. J. drainage system shaft no. 13 shaft no. 2 shaft no. 1 mining area Hamr shaft no. 6 shaft no.. 7 ISL AREA hydraulic barrier ISL Area Mining area Tailings pond Chemical plant area Seat Evaporation statio Hydraulic barrier Stráž fault zone Drainage system Road 2 km 3

4 History of deep mining 1978 start of mining at Hamr I 1982 start of mining at Křížany I end of mining and liquidation of Křížany end of mining and liquidation of Hamr 4

5 History of chemical mining st leaching experiments 1974 beginning of chemical mining 1996 start of the remediation 5

6 Uranium production more than t of uranium deep mining t chemical mining t 6

7 Stráž - chemical treatment plant and tailings ponds 7

8 Schematic cross-section of the area SW Ralsko leaching fields hydrobarrier Stráž drainage system Hamr I mine NE turonian aquifer low turonian semiaquitard cenomanian aquifer crystaline shists cenomanian piezometric level water le vel contamination weak ( g/l) strong ( g/l) 8

9 Principle of hydrobarriere CLEANING URANIUM SEPARATION DISCHARGE cenomanian water level leaching fields strongly concentrated solutions hydrobarriere HAMR I MINE DRAINAGE 9

10 Piezometric heads Before HB construction Ralsko leaching fields HAMR deep mine water level in v cenomanian aquifer cenomanian aquifer contamination semi-permeable layer water level in turonian aquifer turonian aquifer 10

11 Ralsko Piezometric heads Before operation of evaporation station leaching fields HAMR deep mine water level in v cenomanian aquifer cenomanian aquifer contamination semi-permeable layer water level in turonian aquifer turonian aquifer 11

12 Ralsko Piezometric heads Current situation evaporation station at work leaching fields HAMR deep mine water level in v cenomanian aquifer cenomanian aquifer contamination semi-permeable layer water level in turonian aquifer turonian aquifer 12

13 Ralsko Piezometric heads During remediation Hamr mine flooded leaching fields HAMR deep mine water level in v cenomanian aquifer cenomanian aquifer contamination semi-permeable layer water level in turonian aquifer turonian aquifer 13

14 Piezometric heads At the end of remediation process Ralsko leaching fields HAMR deep mine water level in v cenomanian aquifer cenomanian aquifer contamination semi-permeable layer water level in turonian aquifer turonian aquifer 14

15 During chemical leaching technological wells were drilled Area of leaching fields 628 ha Chemicals consumption: H 2 SO 4 HNO 3 NH 4 + HF t t t t 15

16 Scheme of leaching fields Pumping wells Pipelines Turonian horizon Injection wells Permeable turonian horizon Cenomanian horizon Fucoid sandstone Non-permeable lower turonian horizon Friable sandstone Wash-out horizon Opened part of well Fresh-water sediments 16 Uranium ore

17 Present extent of contamination Influenced volume of groundwater - cca 300 mil. m 3 Amount of TDS - 4,8 mil. t There of: SO ,9 mil. t Al t Fe t NH t 17

18 Present extent of contamination Stráž fault model boundary tectonic lines leaching fields cross-section 3 g/l limit 8 g/l limit TDS concentration [g/l] < > 80 18

19 Reaching of safe state in the underground From the ground it is necessary to remove cca 3,7 mil. t of contaminants 19

20 Scheme of present remedial technologies Al (SO ) filtrate U chemical station neutralisation NDS 6 distillate filter cake evaporator alum crystallisation (NH ) SO SH mother liquor alum for fertilisers tailings pond Plouč nice river Turonian aquifer aquitard Cenomanian aquifer ontrol element SH aluminium sulphate production lower beds 20

21 Capacity of present remedial technologies for withdrawing of contamination Production and reprocessing of alum: up to t TDS per year Neutralization: up to t TDS per year Present remediation well net End of remediation

22 Realisation of new remedial technologies II. stage of aluminium sulphate production - end of 2007 Another neutralisation station - end of 2012 Neutralisation of mother liquor - end of

23 Complete scheme of remedial technologies filter cake Al (SO ) neutralisation NDS 10 U filtrate CHEMICKÁ chemical STANICE station neutralisation NDS 6 distillate filtrate ODPARKA evaporator filter cake alum crystallisation neutralisation ML (NH ) SO SH alum for fertilisers SH filter cake tailings pond Plouč nice river Turonian aquifer aquitard Cenomanian aquifer ontrol element SH aluminium sulphate production ML mother liquor lower beds 23

24 Capacity of complete remedial technologies for liquidation of contamination Neutralisation: up to t TDS per year Production and reprocessing of alum and mother liquor liquidation: up to t TDS per year Completed remediation well net End of remediation

25 NATO SPS Study "Prevention and Remediation Issues in Selected Industrial Sectors " Ljubljana, July 2007 Thank you for your attention MINISTRY OF ENVIRONMENT, CZECH REPUBLIC Prague