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MineWall 3 (Version 3.0.1)

Available as a ~40 MB Excel spreadsheet for immediate download for free -
(click on the "Get access code" below, then enter and validate it)



Kevin A. Morin, Minesite Drainage Assessment Group (MDAG)TM

MineWall 3

In the 1990's, the Canadian MEND Program recognized that case studies, monitoring techniques, and models for open-pit and underground mines were generally lacking relative to those for tailings and waste rock. In response, the MEND Program sponsored two consecutive studies called "MineWall" Versions 1.0 and 2.0, (1) to fill this gap, (2) to create a field-investigation technique, and (3) to provide a model to simulate water balances and chemistry.

The MineWall model simulates open pits and underground mines during active dewatering (operation), during transient flooding and geochemical flushing after dewatering is stopped (short-term closure), and after a stable water level has been established (long-term closure). This model includes the geochemical effects of fractured mine walls and of any granular material (like tailings and waste rock) present in or backfilled into the mine.

The MEND report on MineWall 1.0 is Morin (1990). MineWall 2.0 was a series of four reports (Literature Review and Conceptual Models, User's Manual, Application of MINEWALL to Three Minesites, and Programmer's Notes and Source Code) plus one diskette (MEND, 1995). Because these reports contain a total of many hundreds of pages, the MineWall field technique and model have been conveniently summarized by Morin and Hutt (1995, 1997, 1999, 2001a, 2001b, 2004, and 2006). Additional details on the field technique can be found in Andrade and Mountjoy (2015).

In general, MineWall 2.0 was a "compartmental" model that kept track of, during discrete time steps,
 - all inflows of water to the open pit or underground mine including background inflowing or outflowing groundwater,
 - all inflows and outflows such as pumping,
 - the water level within the underground or open-pit mine, and
 - mass-balance chemistry associated with all inflows, outflows, reactive mine walls, and any backfill, which could then optionally be adjusted based on geochemical processes like mass balance, kinetics, and equilibrium mineral precipitation-dissolution.

The original code for MineWall 2.0 was written in Visual Basic for DOS which is no longer operative on the current 64-bit Windows systems. As Morin and Hutt (2006) observed, "If MineWall 2.0 were written today, it would probably be written as an add-on to a spreadsheet application, like Excel".

In fact, the current version of MineWall, Version 3, is a multi-sheet Excel spreadsheet approximately 40 MB in size. It executes more than one hundred thousand calculations, which can take a minute or two on slower computers.

The conceptual model and input data of MineWall 3 adhere closely to MineWall 2.0. As a result, the four MEND MineWall 2.0 documents still apply (MEND, 1995), containing several hundreds of pages of literature review, conceptual models, user's guide, and applied case studies.

A basic concept of MineWall is that the reaction products, such as acidity and zinc, from mine walls and any backfill will alter the aqueous concentrations of inflowing groundwater and net precipitation (e.g., Figure 1 below). During operation and active dewatering, the combined loadings and flows determine the net aqueous pH and concentrations in the water that is removed to keep the mine dry. When closure begins and dewatering ends, the water level in the mine begins rising, flushing out previously non-flushed reaction products. After the water level reaches a stable elevation, only the non-submerged mine walls and backfill continue to react.

Minewall Example

Another basic concept of MineWall is that aqueous concentrations can be estimated in two ways, but typically only one realistically applies to a simulation. These two ways are:
(1) mass balance of all input loadings and output loadings without any adjustments for mineral solubility, or
(2) site-specific pH-dependent maximum equilibrium concentrations with site-specific precipitation-dissolution of minerals (such as Empirical Drainage-Chemistry Models or EDCMs, e.g., Morin, 2016 and 2018, Morin and Hutt 2001c).

Especially for fine-grained backfill and highly fractured mine walls, mass-balance calculations can produce to extremely high "concentrations" that are not realistic even at acidic pH. In this case, site-specific equilibrium concentrations are the appropriate predictions, and they usually are not significantly affected by dilution.

On the other hand, lower-surface-area pit walls and backfill can produce mass-balanced-based concentrations that are less than equilibrium and thus proportionally affected by dilution. In this case, mass-balance concentrations are the appropriate predictions.

It is important to note that some elements and parameters in a simulation might be predicted from equilibrium concentrations (e.g., copper) and others from mass-balance concentrations (e.g., zinc). Therefore, each MineWall simulation requires checking the output for each element and parameter to determine whether equilibrium or mass balance applies to that element.


References

Andrade, C., and K. Mountjoy. 2015. Minewall Stations and Mass Loadings at an Epithermal High Sulfidation Deposit - What, No Scaling? IN: 10th International Conference on Acid Rock Drainage and IMWA Annual Conference, Santiago, Chile, April 20 - 24, 2015.

MEND. 1995. MINEWALL 2.0. Series of four reports (Literature Review, User's Guide, Application of MINEWALL to Three Minesites, and Programmer's Notes and Source Code) plus one diskette. Canadian Mine Environment Neutral Drainage (MEND) Reports 1.15.2a, 1.15.2b, and 1.15.2c,
or download from MDAG here:
    - Literature Review and Conceptual Models
    - User's Manual
    - Application of MINEWALL to Three Minesites
    - Programmer's Notes and Source Code

Morin, K.A. 2018. Wavelet Transforms of Drainage from Highly Reactive Geologic Materials. MDAG Publishing (www.mdag.com), Surrey, British Columbia. ISBN 978-0- 9952149-3-4.

Morin, K.A. 2016. Spectral Analysis of Drainage from Highly Reactive Geologic Materials. MDAG Publishing (www.mdag.com), Surrey, British Columbia. ISBN: 978-0-9952149-1-0.

Morin, K.A. 1990. Acid Drainage from Mine Walls: The Main Zone Pit at Equity Silver Mines. [Minewall 1.0] Canadian MEND Report BCAMD 1.15. Download from the MEND site or from MDAG.

Morin, K.A., and N.M. Hutt. 2006. The MEND Minewall Technique: Overview and Details. IN: Proceedings of the 13th Annual British Columbia MEND ML/ARD Workshop, Vancouver, Canada, November 29-30, 2006.

Morin, K.A., and N.M. Hutt. 2004. The Minewall Approach for estimating the geochemical effects of mine walls on pit lakes. Presented at Pit Lakes 2004; United States Environmental Protection Agency; Reno, Nevada; November 16-18, 2004.

Morin, K.A., and N.M. Hutt. 2001a. Environmental Geochemistry of Minesite Drainage: Practical Theory and Case Studies, Digital Edition. (Section 5.4.2 and Appendix D.) MDAG Publishing (www.mdag.com), Vancouver, British Columbia. ISBN: 0-9682039-1-4.

Morin, K.A., and N.M Hutt. 2001b. Prediction of water chemistry in mine lakes: The minewall technique. Ecological Engineering, Vol. 17, p. 125 - 132.

Morin, K.A., and N.M Hutt. 2001c. A compilation of Empirical Drainage-Chemistry Models. IN: Proceedings of Securing the Future, International Conference on Mining and the Environment, Skellefteċ, Sweden, June 25-July 1, Volume 2, p. 556-565. The Swedish Mining Association.

Morin, K.A., and N.M. Hutt. 1999. Predictions of water chemistry in acid-mine lakes: the Minewall technique. IN: Ecology of Post-Mining Landscapes, 15-19 March 1999, Cottbus, Germany.

Morin, K.A., and N.M. Hutt. 1997. Environmental Geochemistry of Minesite Drainage: Practical Theory and Case Studies. (Section 5.4.2 and Appendix D.) MDAG Publishing (www.mdag.com), Vancouver, British Columbia. ISBN: 0-9682039-0-6.

Morin, K.A., and N.M. Hutt. 1995. MINEWALL 2.0: A technique for predicting water chemistry in open-pit and underground mines. IN: Proceedings of the Conference on Mining and the Environment, Sudbury, Ontario, May 28 - June 1, Volume 3, p.1007-1016.

 

This Minewall 3 (Version 3.0.1) spreadsheet-model is free.
Please click on "Get access code", enter the case-sensitive code, click on "Validate code",
and you will be redirected to the spreadsheet in XLSX format (~40 MB in size).
On slower computers, Minewall 3 may require a minute or two to open and to recalculate each time.


HomeBook: Environmental GeochemistryBook: An IntroductionBook: Spectral AnalysisBook: EFABook: WaveletsMDAG PapersMDAG IKD DatabaseMDAG Grain 3.0Minewall 3


Created by K.Morin