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Mine water derived iron as a national opportunity for phosphate removal
Abby Moorhouse and Ian Watson
Resolving the impacts of mining
Contents• Introduction
• Coal Authority
• Coal mine water treatment
• Ochre generation at coal mine water treatment schemes
• Potential for phosphate removal
• National picture
• Regional ochre chemistry
• Concluding remarks
• Questions
2 Mine water derived iron as a national opportunity for phosphate removal
The role of the Coal AuthorityThe Coal Authority manages the effects of past coal mining
The Coal Authority was established in 1994
We’re responsible for:
• licensing coal mining in Britain
• managing the safety issues that have resulted from years of coal mining
• communicating information to the public
• making mining information available
• dealing with water pollution caused by mining
3 Mine water derived iron as a national opportunity for phosphate removal
Coal AuthorityExpanded our work to include:
Abandoned Non-coal mine sites
• Working with DEFRA + EA on abandoned metal mines in England since 2011
• Currently working on ~20 feasibility studies in England
• Discussions ongoing to work on metal mines in Wales and Scotland
4 Mine water derived iron as a national opportunity for phosphate removal
Coal Authority schemes
5 Mine water derived iron as a national opportunity for phosphate removal
~70 Coal mine water treatment schemes
Passive: gravity fed; aeration cascades; lagoons; reed beds
Semi Passive: pumped water; chemical dosing; aeration cascades; Lagoons; reed beds
Active: Dawdon; Ynysarwed
Non-coal mine water treatment schemes
Passive: Force Crag (Lead-Zinc Mine) Saltburn (Ironstone Mine)
Active: Wheal Jane (Tin Mine)
Coal mine water treatment
6 Mine water derived iron as a national opportunity for phosphate removal
Blenkinsopp Scheme, Northumberland. Google Maps
Conventional coal mine water treatment
7 Mine water derived iron as a national opportunity for phosphate removal
Each year ~ 1,500 tonnes of Iron (as Fe)
produced from mine water treatment schemes
8 Mine water derived iron as a national opportunity for Phosphate removal
De-sludge process
9 Mine water derived iron as a national opportunity for phosphate removal
Dawdon: Filter press
10 Mine water derived iron as a national opportunity for phosphate removal
Iron and phosphate removalIron addition well known method for phosphate removal
Typically ferric chloride is used to form phosphate precipitates
Any remaining iron forms hydroxides which can remove other contaminants
However:
Ochre from coal mine water treatment is Fe-oxyhydroxide
• CA currently investigating options for methods to transform ochre into a useable product
• If successful:• National coverage for material• Environmentally more sustainable as avoid landfill route
11 Mine water derived iron as a national opportunity for phosphate removal
Lamesley scheme
12 Mine water derived iron as a national opportunity for phosphate removal
Co-treatment with Northumbrian Water Ltd
• Built in 2005• Treats 350 L/s• Total of 9 individual reed beds• Reed beds cover an area of 5.5 hectares• Phosphate removal enhanced by presence of
iron in mine water• Ochre precipitation removes suspended
solids in sewage water• Was the largest artificial wetland constructed
in the UK in 2005Lamesley Scheme, Northumberland. Microsoft, 2009
Regional ochre production
13 Mine water derived iron as a national opportunity for phosphate removal
Region Tonnes iron pa Tonnes ochre pa
Scotland 375 720
North East 640 1,220
Lancashire and Yorkshire
230 440
Midlands 70 135
Wales 195 370
Total 1,510 2,885
UK ochre production
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Ochre colour differences
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Ochre sample locations
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RegionMine water treatment scheme
Number of samples analysed
ScotlandFrances, Polkemmet, Pool Farm,
11
North EastAcomb, Bates, Blenkinsopp, Dawdon, Whittle
12
Lancashire and YorkshireDeerplay, Old Meadows, Woolley
7
WalesBlaenavon, Six Bells, Ynysarwed
17
Total 14 Sites 47
Scotland ochre production
17 Mine water derived iron as a national opportunity for phosphate removal
Scotland
18 Mine water derived iron as a national opportunity for phosphate removal
Key Facts:
Iron content typically ~39% (range 23 - 50%)
• Polkemmet ochre has elevated aluminium
• Frances ochre has elevated magnesium
• Pool Farm ochre has low potassium
Site Iron (wt.%)
Calcium (wt.%)
Aluminium (mg/kg)
Manganese (mg/kg)
Magnesium (mg/kg)
Sodium (mg/kg)
Potassium (mg/kg)
Frances 39 2.8 4,865 1,177 3,520 1,359 1,050
Polkemmet 37 1.3 6,509 1,333 2,537 386 848
Pool Farm 40 1.3 2,490 1,235 1,560 - 285
England ochre production
19 Mine water derived iron as a national opportunity for phosphate removal
North East England
20 Mine water derived iron as a national opportunity for phosphate removal
Key Facts:
Iron content typically ~43% (range 35 - 48%)
• North East ochre is typically the “purest” ochre
• Dawdon has low iron and elevated calcium (confirmed in triplicate)
• Bates and Dawdon have saline mine waters
Site Iron (wt.%)
Calcium (wt.%)
Aluminium (mg/kg)
Manganese (mg/kg)
Magnesium (mg/kg)
Sodium (mg/kg)
Potassium (mg/kg)
Acomb 44 0.8 224 235 811 124 92
Bates 36 5.9 1,864 729 3,810 10,927 1,457
Blenkinsopp 46 2.6 1,324 841 1,417 768 272
Dawdon 10 36 593 1,632 3,547 11,997 1,295
Whittle 46 1.3 977 498 3,260 2,188 418
Yorkshire and Lancashire
21 Mine water derived iron as a national opportunity for phosphate removal
Key Facts:
Iron content typically ~37% (range 11 - 46%)
• Old Meadows has elevated aluminium
• Woolley has elevated sodium
Site Iron (wt.%)
Calcium (wt.%)
Aluminium (mg/kg)
Manganese (mg/kg)
Magnesium (mg/kg)
Sodium (mg/kg)
Potassium (mg/kg)
Deerplay 46 1.8 773 1,412 514 471 246
Old Meadows 27 0.8 11,500 680 860 145 636
Woolley 37 7.3 1,136 1,819 2,155 4,645 598
South Wales ochre production
22 Mine water derived iron as a national opportunity for phosphate removal
South Wales
23 Mine water derived iron as a national opportunity for phosphate removal
Key Facts:
Iron content typically ~37% (range 25 - 50%)
• Ynysarwed has elevated magnesium
• Six Bells has elevated sodium
• Blaenavon has elevated manganese and also contains detectable PAH
Site Iron (wt.%)
Calcium (wt.%)
Aluminium (mg/kg)
Manganese (mg/kg)
Magnesium (mg/kg)
Sodium (mg/kg)
Potassium (mg/kg)
Six Bells 46 6 1,720 600 1,743 1,604 962
Ynysarwed 33 9 2,513 993 15,937 614 370
Blaenavon 31 2.4 3,278 21,881 1,387 206 1,627
Regional variation
24 Mine water derived iron as a national opportunity for phosphate removal
Key Facts:
• North East: highest iron and elevated sodium
• South Wales: elevated calcium, manganese, magnesium and potassium - driven by Blaenavon (Mn, K) and Ynysarwed (Mg)
• Scotland: elevated aluminium
• Yorkshire and Lancashire: elevated aluminium and low magnesium
Site Iron (wt.%)
Calcium (wt.%)
Aluminium (mg/kg)
Manganese (mg/kg)
Magnesium (mg/kg)
Sodium (mg/kg)
Potassium (mg/kg)
Scotland 39 2 4,621 1,248 2,539 873 728
North East(ex. Dawdon) 43 3 1,097 576 2,325 3,502 560
Yorkshire/Lancashire 37 3 4,440 1,304 1,176 1,754 493
South Wales 37 6 2,504 7,825 6,356 808 986
SummaryUK-wide production of ochre
• Currently ~ 2,900 tonnes ochre pa• North East England has the highest
annual ochre production• Ochre generally quite pure with limited
metal impurities
Regional ochre chemical variation:• North East ochre typically contains the
highest iron content• Dawdon ochre has the lowest iron and
highest calcium content• Welsh ochre has elevated magnesium
and manganese
25 Mine water derived iron as a national opportunity for phosphate removal
For further details please contact:
Abby Moorhouse Ian WatsonGeochemist Principal Hydrogeologist01623 637388 or 07770 678383 01623 637305 or 07919 [email protected] [email protected]
Resolving the impacts of mining