Passive Arsenic Removal from Water

Earth Systems has designed and installed a Permeable Reactive Barrier (PRB) to intercept and contain surface runoff and shallow groundwater containing elevated dissolved arsenic from a derelict mine site.

The PRB removes soluble arsenic by adsorbing it to the reactive minerals. A suitable PRB substrate was identified and subjected to a series of geochemical and mineralogical tests.

The typical untreated (inflow) water is acid (pH ~3.5) with elevated concentrations of dissolved arsenic (20-60 mg/L), as well as elevated copper, cadmium, zinc, antimony, aluminium, and lead.  Indicative water chemistry monitoring shows arsenic removal efficiencies of greater than 98%, and significant removal of other contaminants.

To read more download a copy of the case study here.

For more information on this, or any other news item, contact Earth Systems.

Existing Downhole Data – New Knowledge with ImpactScan

Unlock environmental and resource information from your geological database using ImpactScan.

With the increased use of hyperspectral (HyLogger, Corescan, Terracore, PIMA) and X-Ray Diffraction data in resource assessment, exploration and mining companies have access to more detailed mineralogical data than ever before.  But is this data being transformed into information?

Earth Systems has developed a series of algorithms that convert mineralogical and geochemical data into information that can be used to model and predict key environmental outcomes.  With the right data inputs our algorithms can reveal potential hazards posed by:


  • Acid & Metalliferous Drainage (AMD) / Acid Rock Drainage (ARD).
  • Leachate water quality issues.
  • Radioactive and fibrous minerals.
  • Geological materials prone to sodicity and dispersivity (erosion).
  • Greenhouse gas emissions from geological materials.


ImpactScan enables improved assessment and management of environmental outcomes. An example report file (converted to PDF format) can be downloaded here.
Contact Earth Systems or call +61 3 9810 7500 for a quote.

AMD Treatment for Discharge from a Quarry

Acid and Metalliferous Drainage Treatment for Discharge from a Quarry

Earth Systems was engaged to devise and implement a treatment strategy for two pit lakes containing acid and metalliferous (AMD) water at a quarry in Tasmania.  To resume activities at the quarry, contaminated water needed to be treated and safely discharged in a way that complies with the ANZECC water quality guidelines for the protection of more than 95 % of species.

Optimum target pH and reagent types were determined based on an in-house water quality treatment tool, TREATSim.  A dosing method was designed to meet on-site conditions.

Both ponds were successfully treated with greater than 98 % reductions in metal concentrations within 2 weeks of commencement.  A discharge method was developed to minimise erosion at the discharge point and facilitates mixing and dilution with the receiving environment.

For more information on this, or any other news item, contact Earth Systems.

Treatment of AMD at a Derelict Mine Site

Treatment of Acid and Metalliferous Drainage at a Derelict Mine Site

Earth Systems was engaged to provide water treatment services at a derelict mine site in NSW to prevent the uncontrolled discharge of acid and metalliferous water into the surrounding environment. Optimum target pH and reagent types including alkali and flocculant were determined based on an in-house water quality treatment tool.

A dosing strategy was implemented to permit rapid equilibration at surface and depth. Uniform metal removal via precipitation and adsorption was completed. Within a few days 99% metal removal was achieved enabling safe discharge to the local river.

The discharged water quality complied with ANZECC water quality guidelines for the protection of better than 95 % of species for all identified metals of concern and was generally better than the background downstream water quality.

Water quality of the dam before and after treatment for all identified metals of concern in comparison with ANZECC (2000) water quality guidelines. Concentrations indicated are in mg/L.

Analyte Dam water quality
– Before treatment
Dam water quality
– After treatment
ANZECC (2000) 95% guideline value *
Arsenic <0.02 <0.001 0.013
Cadmium 0.486 <0.0001 0.0002
Copper 2.08 0.001 0.0014
Lead 4.33 <0.001 0.0034
Nickel 0.04 <0.001 0.011
Zinc 108 <0.005 0.008

* ANZECC and ARMCANZ (2000).  Australian and New Zealand Guidelines for Fresh and Marine Water Quality.  Australian and New Zealand Environment and Conservation Council & Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

For more information on this, or any other news item, contact Earth Systems.

New ARD / AMD Prevention Technology

New ARD / AMD Prevention Technology

Water SamplingIn the battle to manage ARD/AMD, significant technological breakthroughs are few and far between.  At the 9th Australian AMD Workshop in Burnie (November, 2017), Earth Systems announced a major advance in the prevention of ARD / AMD (acid and metalliferous drainage) from underground mines.  The technology is applied in a two-stage process.  Stage 1 involves engineering works that do not affect mine water discharge rates or water levels, but provide a primary control on air-entry into mine voids.  Lowering air resupply into mine voids to levels that are below sulfide oxidation rates results in decreases in pollution production.  Every cubic metre of oxygen consumed by sulfide oxidation within a mine void is replaced by a cubic metre of air, which only contains ~21 volume % oxygen.  Hence if Stage 1 works are comprehensive, mine void oxygen reduction and nitrogen enrichment is inevitable.

Extensive monitoring from case study sites demonstrates that mine voids breathe in a process we refer to as barometric pumping.  Voids “inhale” with the progress of external “high-pressure” weather systems, and “exhale” with atmospheric pressure drops associated with “low-pressure” fronts.  While acid generation with a void can be fuelled during increasing atmospheric pressure scenarios, sulfide oxidation is unlikely to be related to the exhalation of nitrogen-rich gas from mine voids during decreasing external pressure scenarios.  Consequently, effective Stage 1 works should be able to routinely halve acid generation processes.

To overcome the effects of barometric pumping during the passage of high pressure systems, Stage 2 works require the installation of inert gas injection systems.  Such systems need to be configured to provide very small internal gas overpressures to counteract air entry due to external (climatic) pressure increases.  In this way, inert gas can be used to prevent sulfide oxidation within mine voids.

Stage 1 inert atmosphere installations have been completed at two decommissioned metal mines in New South Wales (NSW), Australia, and monitoring is ongoing.  These rehabilitation works were funded by the NSW State Government Legacy Mine Program.  One site has been lowered by 50% and a 70% reduction has been recorded at the other site after less than 12 months.  The case studies have provided unambiguous proof of concept, and the improvement at one site has far exceeded expectations.

High priority targets for application of this technology are legacy underground mines that are currently committed to treating in perpetuity.  Close to 200 sites in this category have been identified worldwide.  Dramatic reductions in treatment costs are the minimum expectation from this new remedial approach.  Additional benefits include avoiding sludge production, lowering public safety risk and the ability to rapidly reinstate a site to a minable status.

DOWNLOAD: Preventing Pollutions from Underground Mines.pdf

For additional information on this method, please contact Dr Jeff Taylor at Earth Systems ([email protected] or +61 402 158 682).

Mine Pit Lake Treatment

Case Study

Mine Pit Lake Treatment, South Australia.

Earth Systems was engaged to undertake treatment of 120 ML of highly acidic pit water. The Client intended to recommence mining operations in the pit but faced the multi-faceted challenge of treatment and discharge of pit water. The level of difficultly of the treatment and discharge process was increased by the physical inaccessibility of the pit lake itself.

Download Case Study.

Kinetic Testwork for Mine Planning, Metal Recovery, Environmental and OH&S Management and Mine Closure

Kinetic Testwork for Mine Planning, Metal Recovery, Environmental and OH&S Management and Mine Closure

Kinetic testwork in the form of column leach and humidity cell testwork is widely used for mining approvals to assess the indicative chemistry of leachate from sulfidic mine wastes. Advanced kinetic testwork methods based on oxygen consumption measurements can also reveal, a) the likely duration of sulfide oxidation processes, b) an accurate assessment of lag times (time before the onset of acid conditions), and c) the likely pollution loads over time. Oxygen consumption measurement techniques permit the quantitative assessment of sulfide oxidation rates (i.e. pollution generation rates) as a function of key waste storage facility variables such as temperature, moisture content, particle size distribution, oxygen concentration, pore water pH, and bacterial activity. Covers for sulfide wastes, capping zones, thin-lift and compacted oxygen control (encapsulation) bands and oxygen consuming layers can be accurately tested in the laboratory and field to optimise installation configurations (e.g. composition, particle size distribution, thickness, compaction, etc.) for operations and closure.

Oxygen consumption testwork on sulfidic materials is also finding increasing application to metal recovery and related metallurgical applications. A detailed understanding of the geochemical behaviour of ore materials can quantify a diverse range of outcomes including, a) establishing the relationship between sulfide oxidation and gold recovery, b) determining the rate of natural copper loss from long term copper ore stockpiles, c) specifying the precise neutralisation requirement for a gold heap leach operation as a function of time and oxygen concentration, d) determining reagent requirements for oxidation and neutralisation to complete metal leaching processes, and e) quantifying the optimum duration of a heap leach operation. Rapid response and portable oxygen consumption techniques can also be applied to assess the spontaneous combustion risk of sulfidic materials in the field.

Uptake by the mining industry of oxygen consumption techniques for a range of applications is increasing as the testwork, a) provides improved simulation of real-world scenarios, b) accurately assesses more key variables than conventional kinetic tests, c) produces more accurate outputs, far more rapidly and at a much lower cost, and d) can be used in both laboratory and field settings. Key benefits include rapidly facilitating approvals, improving OH&S for workers dealing with spontaneous combustion, increasing operational profits and lowering closure and remediation costs.

For assistance with kinetic testwork programs, or more information on the additional applications of kinetic testwork contact Earth Systems.

Latest version of ABATES – Acid-Base Accounting Tools now available for download

ABATES – Acid Base Accounting Tools from Earth Systems


The latest version of Earth Systems acid-base accounting tools is available for download here or from our AMD Tools page.

ABATES is an excel-based tool that contains an:

  • acidity calculator,
  • charge balance estimator,
  • NAPP estimator using weight percent mineral abundances
  • NAPP estimator using visual estimates of mineral abundances

Contact Earth Systems for more information.

Assessing AMD Risk Using Bulk Rock Chemistry to Estimate Mineralogy

Converting Bulk Rock Chemistry to Mineralogy for Acid and Metalliferous Drainage Risk Management.

Static geochemical data provides the foundation for quantifying the risk posed by sulfidic mine materials, including waste rock, tailings, wall rock, ore and low grade ore stockpiles, heap leach pads and concentrate stockpiles.  A new approach to developing a detailed acid and metalliferous drainage (AMD) risk layer for a mine model was recently developed for the Olympic Dam Fe-oxide Cu-U-Au-Ag deposit.

Major and trace element chemistry data from all resource drillholes are routinely collected at Olympic Dam.  Sixty five analytical parameters, including carbon dioxide, were measured for a dataset of 10,000 samples, each representing a 15 metre drillhole intersection.  A program was developed to allocate the chemical components to 30 ore and gangue minerals known to occur at Olympic Dam, resulting in the production of a highly detailed modal mineralogy for each analysed intersection.  The maximum potential acidity (MPA) and acid neutralising capacity (ANC) values were calculated from the key reactive minerals in each intersection.  Key acidity generating minerals included pyrite, chalcopyrite, bornite and chalcocite.  The dominant acid neutralising minerals included dolomite and ankerite; however, abundant siderite was also present.  Net acid producing potential (NAPP) values were calculated from the MPA and ANC from each sample. AMD classification data identifying non-acid forming (NAF) and potentially acid forming (PAF) materials based on calculated NAPP values was produced for part of the deposit.  Two hundred and fifty samples of drillhole material were collected and submitted to a NATA accredited laboratory for static geochemical analysis to assess the accuracy of the calculated mineralogy and associated NAPP values.  The AMD risk classification for the laboratory data and the calculated mineralogy was shown to be well correlated.

From this work it is concluded that bulk rock chemistry data can be used to accurately calculate mineralogy to develop AMD risk layers for mine block models, potentially dramatically improving AMD management and closure outcomes without the need for additional laboratory-generated geochemical data and at very little relative and absolute cost.

Submitted as an abstract to 9th Australian Workshop on Acid and Metalliferous Drainage.

For more information on the application of this technique to your site contact Earth Systems.

Waste Rock Pile Design to Lower Closure and Relinquishment Costs

Waste Rock Pile Construction to Lower Closure and Relinquishment Costs

BULC Waste Rock Pile
Earth Systems integrates leading practice AMD management with mine planning by developing a new approach for construction of sulfidic waste rock piles. Referred to as the Base-Up, Layered and Compacted (BULC) construction method, it offers numerous advantages over conventional waste dumping methods. The BULC construction method employs geochemical engineering principles to overcome persistent AMD issues associated with conventional waste rock dumping approaches. The upfront cost of this new approach can be far outweighted by the savings associated with other AMD management and water treatment costs, during the operations and post-closure phases of a mining project.

Click here for more details.