1. GEOCHEMICAL MODULE FOR “AMDTreat” Charles A. Cravotta III and David L. Parkhurst, U.S. Geological Survey Brent P. Means, Robert M. McKenzie, and Bill Arthur, U.S. Office of Surface Mining Reclamation and Enforcement 2011 West Virginia Mine Drainage Task Force Symposium, Morgantown, WV

2. Version 5.0 is coming soon!

3. CONCLUSIONS Empirical and simulated titrations indicate that: Al and Fe III may be effectively removed at pH <6-8 by precipitation of hydroxide minerals; Fe II may be removed at pH > 8.5 as Fe(OH) 2 and Mn may be removed at pH > 9.5 as Mn(OH) 2 ; At high pH needed to precipitate Mn(OH) 2, other constituents such as Mg and Ca can precipitate, consuming caustic reagents and adding to sludge.

4. CONCLUSIONS MnO 2, Fe(OH) 3, and other oxidized compounds may precipitate at low pH (~6); Chemical consumption can be decreased by avoiding precipitation of Mg and Ca compounds. If oxidized before addition of caustic chemicals : With titration simulation “add-in” to AMDTreat, costs for treatment with various chemicals and corresponding effluent quality can be estimated.

5. Passive/Active Treatment Al 3+ Fe 2+ / Fe 3+ Mn 2+ Alter chemistry with natural substrates & microbial activity Reactions slow Large area footprint Low maintenance ActivePassive Alter chemistry with aeration & reagents Reactions fast, efficient Moderate area footprint High maintenance

6. Common nameChemicalFormula caustic sodasodium hydroxide NaOH quick limecalcium oxideCaO hydrated limecalcium hydroxideCa(OH) 2 soda ashsodium carbonateNa 2 CO 3 ammoniaanhydrous ammoniaNH 3 Caustic Chemicals

7. AMDTreat AMDTreat input screen-- Flow, net acidity, iron, aluminum, manganese, and sulfate are used for size and cost calculations.

8. AMDTreat Chemical Cost Screen: Net Acidity or Titration to Estimate Caustic $618,917/yr

9. AMDTreat Chemical Cost Screen: Net Acidity or Titration to Estimate Caustic $736,944/yr

10. Metal Hydroxide Solubility vs. pH Fe III Fe II Mn IV Mn III Mg Al Mn II Ca

11. NaOH + H +  H 2 O + Na + NaOH + CO 2 (aq) = HCO 3 - + Na + 3 NaOH + Al 3+  Al(OH) 3 + 3 Na + 3 NaOH + Fe 3+  Fe(OH) 3 + 3 Na + 2 NaOH + Fe 2+  Fe(OH) 2 + 2 Na + 2 NaOH + Mn 2+  Mn(OH) 2 + 2 Na + 2 NaOH + Mg 2+  Mg(OH) 2 + 2 Na + Neutralization of Acidity

12. Precipitation of Solid Hydroxide Compounds: Al 3+ + 3 OH -  Al(OH) 3 {pH >5.0} Fe 3+ + 3 OH -  Fe III (OH) 3 {pH >4.0} Fe 2+ + 2 OH -  Fe II (OH) 2 {pH >8.5} Fe 2+ + 2 OH - + 0.25 O 2 + 0.5 H 2 O  Fe III (OH) 3 Mn 2+ + 2 OH -  Mn II (OH) 2 {pH >9.5} Mn 2+ + 2 OH - + 0.5 O 2  Mn IV O 2 + H 2 O Acidity = Base Consumption

13. Fe III Hydroxide Solubility K4K4 K3K3 K2K2 K1K1

14. Solubility of Modeled Solid Phases

15. Titration of “Cal Pike” 20% Caustic Soda

16. Mn Mg Ca SO 4 Fe Al Alk

17. Simulated Titration of “Cal Pike”

18. Simulated Titration of “Cal Pike” – noeq (AlOOH) (Al 4 (OH) 10 SO 4 ) (MnO 2 ) (MnCO 3 ) (Mn(OH) 2 ) (Mg(OH) 2 ) (Ca 6 Al 2 (SO 4 ) 3 (OH) 12. 26H 2 O)

19. Simulated Titration of “Cal Pike” – noeq

20. Simulated Titration of “Cal Pike” – pre-ox (AlOOH) (Al 4 (OH) 10 SO 4 ) (MnO 2 ) (MnCO 3 ) (Mn(OH) 2 ) (Mg(OH) 2 ) (Ca 6 Al 2 (SO 4 ) 3 (OH) 12. 26H 2 O)

21. Simulated Titration of “Cal Pike” – pre-ox

22. AMDTreat “New” AMDTreat input screen-- T0: Net acidity used to compute chemical cost. For PHREEQ titration, need data for Ca, Mg, Na, Cl, & TIC or alkalinity. $0.400 / 1000 gal

23. AMDTreat Chemical Cost Screen: PHREEQ “titration amount” & effluent quality $363,387/yr

24. AMDTreat Chemical Cost Screen: PHREEQ “titration amount” & effluent quality $363,387/yr

25. AMDTreat “New” AMDTreat input screen-- T1: PHREEQ titration w/o aeration used to compute hydrated lime cost. $0.690 / 1000 gal

26. AMDTreat Chemical Cost Screen: PHREEQ “titration amount” & effluent quality $127,721/yr

27. AMDTreat Chemical Cost Screen: PHREEQ “titration amount” & effluent quality $127,721/yr

28. AMDTreat “New” AMDTreat input screen-- T2: PHREEQ titration w/ aeration used to compute hydrated lime cost. $0.242 / 1000 gal

29. AMDTreat MARCH 2011 STATUS OF PHREEQ-N-AMDTreat PHREEQ titration models standardized to simulate results of empirical titrations on six AMD sources; Recoding and coupling of PHREEQ and AMDTreat using FoxPro language completed; Modifications of AMDTreat water-quality, chemical cost, and sludge screens using PHREEQ output and Alpha testing in progress; Beta testing planned for spring-summer 2011.

30. AMDTreat AMD Treatment Cost Estimate http://amd.osmre.gov/downloads.htm