0
Backfilling
technologies for
Estonian oil shale
mines
Ingo Valgma
Tallinn University of Technology
Department of Mining
mi...
Estonia

EGK

2

mi.ttu.ee
Mineral resources in Estonia

3

mi.ttu.ee
Oil Shale mining area

4

mi.ttu.ee
Oil Shale deposit
• Oil shale deposit is located partly in farming
district
• Used for: power generation, 90% electricity
...
Oil shale deposit
• Largest number of underground mines was
13 with a total output of 17 million tonnes
per year ( 31Mt/y ...
Oil Shale
• Losses in pillars increase up to 40 %.
• Large amount of neutral (limestone) and
hazardous waste (ash) is gene...
Steps
• 1. Underground and surface mining
space modeling
• 2. Tests for the fill material
• 3. Determination of technologi...
Where and why?
• A quasi-stable area has been detected
in large areas. Areas of collapse,
subsidence and zones of stabilit...
10

mi.ttu.ee
Oil shale deposit

11

mi.ttu.ee
Backfill mix components
• Water, limestone (waste rock from
oil shale mining), ash
• If limestone could be separated from
...
Selective crushing
(stripping)

12.07.2013

http://mi.ttu.ee/opik/

13

mi.ttu.ee
Tests
• - dry casting of waste rock to the mined out
rooms and adding ash and water mixture
• - pumping wet mixture with p...
Backfilling tests

15

mi.ttu.ee
Tests with samples
• 8 degrees C temperature and 90% humidity
• + keeping in water

16

mi.ttu.ee
17

mi.ttu.ee
• Warming effect – higher UCS, increases
to 10MPa
• Higher water content resulted in higher
compressive strength

18

mi.t...
Surface mine backfilling
• Space between the spoils could be used for
depositing ash and at the same time for
stabilising ...
Backfilling
technology?

12.07.2013

20

mi.ttu.ee
Information

mi.ttu.ee/oilshale
ingo.valgma@ttu.ee
21

mi.ttu.ee
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Valgma backfilling technologies for estonian oil shale mines(2)

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Transcript of "Valgma backfilling technologies for estonian oil shale mines(2)"

  1. 1. Backfilling technologies for Estonian oil shale mines Ingo Valgma Tallinn University of Technology Department of Mining mi.ttu.ee
  2. 2. Estonia EGK 2 mi.ttu.ee
  3. 3. Mineral resources in Estonia 3 mi.ttu.ee
  4. 4. Oil Shale mining area 4 mi.ttu.ee
  5. 5. Oil Shale deposit • Oil shale deposit is located partly in farming district • Used for: power generation, 90% electricity in Estonia, oil, chemistry, thermal power. • Half is underground room and pillar mining • About 7 million tonnes of oil shale per year • Plus separated limestone 40% • +7 Mt/y surface mining 5 mi.ttu.ee
  6. 6. Oil shale deposit • Largest number of underground mines was 13 with a total output of 17 million tonnes per year ( 31Mt/y total) • Depth 80 m, Seam thickness 2,8 m. 6 mi.ttu.ee
  7. 7. Oil Shale • Losses in pillars increase up to 40 %. • Large amount of neutral (limestone) and hazardous waste (ash) is generated • Using ash and limestone as backfilling materials could reduce the volume and area required for surface disposal • The main source of the backfill material today is Heavy Media Separation (HMS). Oil shale seam consists 30 to 50% of limestone 7 mi.ttu.ee
  8. 8. Steps • 1. Underground and surface mining space modeling • 2. Tests for the fill material • 3. Determination of technological schemes for backfilling 8 mi.ttu.ee
  9. 9. Where and why? • A quasi-stable area has been detected in large areas. Areas of collapse, subsidence and zones of stability have been determined. 9 mi.ttu.ee
  10. 10. 10 mi.ttu.ee
  11. 11. Oil shale deposit 11 mi.ttu.ee
  12. 12. Backfill mix components • Water, limestone (waste rock from oil shale mining), ash • If limestone could be separated from the oil shale in situ -> reduction in haulage costs • Dry separation -> tests in drums • + crushing buckets 12 mi.ttu.ee
  13. 13. Selective crushing (stripping) 12.07.2013 http://mi.ttu.ee/opik/ 13 mi.ttu.ee
  14. 14. Tests • - dry casting of waste rock to the mined out rooms and adding ash and water mixture • - pumping wet mixture with piston pump to the rooms • Experiments continued with new ashes (new burning and heating technologies) and waste rock aggregates. 14 mi.ttu.ee
  15. 15. Backfilling tests 15 mi.ttu.ee
  16. 16. Tests with samples • 8 degrees C temperature and 90% humidity • + keeping in water 16 mi.ttu.ee
  17. 17. 17 mi.ttu.ee
  18. 18. • Warming effect – higher UCS, increases to 10MPa • Higher water content resulted in higher compressive strength 18 mi.ttu.ee
  19. 19. Surface mine backfilling • Space between the spoils could be used for depositing ash and at the same time for stabilising spoils. • Increase overburden thickness • Peat and quaternary sediments could be mixed with ash. 19 mi.ttu.ee
  20. 20. Backfilling technology? 12.07.2013 20 mi.ttu.ee
  21. 21. Information mi.ttu.ee/oilshale ingo.valgma@ttu.ee 21 mi.ttu.ee
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