Gold Tailings Pond Water Treatment with VSEP®
VSEP provides a modern, single‑step membrane approach for treating gold tailings pond water, replacing multi‑stage chemical and biological treatment trains. Unlike conventional RO, VSEP handles high scaling, high TDS, and cyanide‑bearing mine effluent using vibratory shear to prevent fouling. Mines use VSEP to reduce pond volume, meet discharge limits, and lower OPEX—without chemical dosing or large treatment footprints.
How Gold is Made
Gold is normally extremely unreactive. Fortunately for lovers of the metal, there is one way to dissolve gold using by the Elsner reaction. Gold normally resists oxidation, however cyanide lowers the energy barrier allowing oxygen to oxidize gold by removing electrons creating gold ions that enter in solution and then forms a very stable bond with cyanide. This is known as dicyanoaurate, a soluble complex.
4Au + 8NaCN + O2 + H2O → 4Na[Au(CN)2] + 4NaOH
Methods vary, however, when gold ore is crushed and milled to a fine powder, it is put through a leach solution at a pH of 10-11 with 200-500 mg/L CN, dissolved oxygen, and water. This dissolves the gold from the pulverized ore which is then removed as tailings.
Activated carbon is added and has a slight positive surface charge with a lot of exposed area. Dicyanoaurate is negatively charged. The carbon adsorbs the complex due to electrostatic attraction, the complex is thermodynamically more stable in the hydrophobic pore region, and also due to van der Waals interactions. The gold bearing carbon is then removed from the spent leach solution and soaked in hot caustic. This releases the dicyanoaurate into solution again. This then goes to electrowinning where the gold cyanide bond is broken by plating the gold out on a cathode.
How Gold Processing Generates Tailings Pond Effluent:
The leach solution containing cyanide and the caustic solution are both recycled and little waste is generated. However, there are bleed streams that are needed to prevent cycling up of contaminants and unwanted metals and sulfates. These bleed streams are sent to a tailings storage facility TSF) or tailings pond.
Other miscellaneous effluents diverted to the TSF include:
- Slurry washing
- Carbon screening and wash water
- Tailings thickener overflow
- Detoxification effluent (cyanide destruction)
The tailings pond volume grows with time and becomes a complex mixture minerals and organics. If the storage size is not increased, the effluent water will be treated to maintain safe lined pond levels. At the time of closure, often the effluent is treated and discharged. In some cases, solar evaporation can remove water and in other cases capping and leaving in place is done.
Classical Effluent Treatment for Tailings Pond Effluent
Chemical treatment prior to discharge is usually required, but chemical treatment alone is almost never enough to meet modern limits. Mines typically use multi‑stage treatment trains because the water coming from a tailings storage facility (TSF) contains a complex mixture of contaminants that no single process can fully address. When treated and discharged, the typical tailings pond water could looks like this:
Typical Composition of Gold Tailings Pond Water (Rough Estimate)
| Parameter | Estimated Range | Comment |
| TDS | 2,000 – 6,000 mg/L | Driven by evaporation & recycling |
| Sulfate | 300 – 1,500 mg/L | Gypsum-controlled; major scaling contributor |
| TSS | 50 – 300 mg/L (typ.) | Ultra‑fines; occasional spikes >500 mg/L |
| Calcium | 150 – 400 mg/L | Lime addition + gypsum |
| Magnesium | 20 – 80 mg/L | Natural background |
| Sodium | 100 – 400 mg/L | Reagent + groundwater |
| Iron | <0.1 – 1 mg/L | High pH suppresses |
| Aluminum | <0.1 – 1 mg/L | High pH suppresses |
| Copper | <0.05 – 0.2 mg/L | Low for oxide ore |
| Zinc | <0.05 – 0.2 mg/L | Typically minor |
| pH | 9.0 – 10.5 | Lime addition |
| Ammonia | 1 – 10 mg/L | CN degradation product |
| Nitrate | 5 – 50 mg/L | Common tailings pond buildup |
Regulatory Requirement for Gold Mine Water Treatment Technologies (Nevada Example)
These vary by state/country, but typical modern limits are:
| Parameter | Typical Limit |
| Copper | 5–20 µg/L |
| Zinc | 30–120 µg/L |
| Selenium | 2–5 µg/L |
| Arsenic | 10 µg/L |
| Ammonia | 1–5 mg/L |
| Nitrate | 5–10 mg/L |
| Cyanide (WAD) | < 0.05–0.2 mg/L |
Typical Nevada Mine‑Water Discharge Treatment Train
Nevada mines operate under Nevada Division of Environmental Protection (NDEP) water pollution control permits, which require meeting stringent limits before any water is released to the environment. The exact configuration varies by mine, but nearly all Nevada hard‑rock operations use the gold tailings pond treatment below.
- pH Adjustment (Acid/CO₂ Conditioning)
- Primary Chemical Treatment: Metal Precipitation + Coagulation/Flocculation
- Solid–Liquid Separation (Clarifier or High‑Rate Thickener)
- Biological Treatment (Critical for Nevada Discharge) for NH3, Se, NO3, SCN
- Nitrification/Denitrification Bioreactors
- Thiocyanate Biodegradation
- Selenium Biological Reduction
Bodie – An Abandoned Gold Mine in California
VSEP – A Better Modern Advanced Treatment Option
Lime softening for water treatment was used in the 1800s. Biological effluent treatment goes back to the Roman times. These old methods are problematic but have been cemented in to many industries because that is how everyone does it. Now, in the 21st century, there are better, more reliable, and less expensive ways to do it.
Problems with the Conventional TSF Effluent Treatment system:
- Complex multistep process where dissimilar technologies work in series
- Large chemical consumption, sludge production, and operating cost
- Large space requirements and heavy operator involvement
- Biological systems are prone to upsets and downtime
- Treated water may not consistently meet requirements
- Systems are adversely affected by loading rates and temperature
Solution – VSEP (Vibratory Shear Enhanced Processing) with RO
- Small compact design
- Fully automated, little to no operator management
- Can be monitored from a central control room
- Removes all contaminants in one step
- Produces ultrapure water exceeding discharge limits
- No chemicals added to the effluent
- Systems are modular and expandable
How VSEP Works on High-Scaling Mining Waters
Our vibratory membrane system works in two ways to overcome solubility limits. First, the membrane is oscillated 50 times per second. This creates very high shear at the membrane surface that prevents concentration polarization. With standard spiral membrane systems, crossflow is used to create shear, but because of the drag from the membrane, this shear decays and becomes non-existent at the membrane surface. Because of this, solids accumulate right at the membrane and become more concentrated. This is concentration polarization. Because there is very high solids concentration at the membrane, precipitation and scaling will occur. With VSEP, this high concentration at the membrane does not occur.
The other way that our system overcomes solubility limits is the agitation. Agitation influences nucleation because it alters the physical and chemical environment where nuclei form. One perfect example is a pot of boiling water. The air bubbles propagate from a nucleation site on the wall of the pot. But as soon as you start to stir this pot, the air bubbles will stop forming. In VSEP, the shear rate is very high right at the membrane, but, the shear decays in a very short distance from the membrane. Away from the membrane in the bulk flow where the rate of shear has decayed and there is very little agitation, clusters of crystals and suspended solids offer very attractive nucleation sites that are thermodynamically stable and this is where precipitation will occur in our system. Because of these two factors, our membrane system can exceed solubility limits and can actually precipitate solids during filtration like a membrane crystallizer.
Quality of VSEP RO Permeate for Typical TSF Effluent (Example)
| Parameter | TSF Effluent | VSEP RO Permeate | Discharge Limit |
| Aluminum | 0.5 mg/L | 0.017 mg/L | |
| Calcium | 300 mg/L | 18.75 mg/L | |
| Copper | 0.15 mg/L | ND | 0.01 mg/L |
| Iron | 0.5 mg/L | ND | |
| Magnesium | 60 mg/L | 2.96 mg/L | |
| Sodium | 250 mg/L | 33.12 mg/L | |
| Zinc | 0.15 mg/L | 0.003 mg/L | 0.03 mg/L |
| Ammonia | 5 mg/L | 0.5 mg/L | 1.0 mg/L |
| Sulfate | 900 mg/L | 13.7 mg/L | |
| Nitrogen | 25 mg/L | 2.4 mg/L | 5.0 mg/L |
| TSS | 175 mg/L | ND | |
| TDS | 4,000 mg/L | 317 mg/L |
Typical VSEP Process Diagram
VSEP Limitations and Design Considerations
- Recovery limited by osmotic pressure (TDS) and viscosity
- Performance will vary based on TSF composition
- Temperature affects throughput
- Prescreening is required to remove solids >100 µm
- VSEP cannot accept aromatic solvents and oxidizers
Design note: Actual performance is site‑specific. We pilot test to select membrane type, flux, recovery, and pretreatment options. Chemistry varies by ore body, beneficiation method, and plant configuration. Final system sizing, membrane selection, and performance projections are only provided after pilot validation
The above information is illustrative only. New Logic has not tested gold tailings pond water since most people just store it, however, VSEP has been tested and installed at many similar mine projects including:
- TENORM Transport Water
- Calcium Carbonate Dewatering
- Copper Hydroxide Filtration
- Titanium Dioxide Dewatering
- Other Tailings Pond Waters
- Coal Slurry Dewatering
- Precious Metals Recovery
- Phosphate Mine Effluent and Phosphoric Acid Purification
How do We Validate Performance for Mine Water Treatment?
- Bench-scale testing
- Onsite pilot testing (7-30 days typical)
- Parameters measured: flux, temperature, pressure, rejection rates, recovery rate
- Deliverables: projection reports, membrane selection, pretreatment design
Get Started
If you are evaluating ways to recycle water, manage TSF pond levels, remediate seepage, or treat effluent for discharge—VSEP can help.
- Request a free VSEP performance projection for your tailings water:info@vsep.com
- View All Case Studies: https://www.vsep.com/case-studies/
- Learn More About the Technology: https://www.vsep.com/technology/
- Read: How VSEP Treats RO Reject & High TDS Brines
About VSEP and New Logic Research
- Over 30 years of membrane system design and manufacturing
- More than 450 industrial VSEP systems installed globally
- Technology covered by U.S. and international patents
- Used in mining, chemicals, food, wastewater, and chemical processing
- Engineering team with chemical, metallurgical, and mechanical engineering backgrounds
Gold Tailings Pond Treatment – Frequently Asked Questions (FAQ)
1. Can membrane systems treat gold tailings pond water?
Yes. Modern membrane systems—especially high‑shear systems like VSEP (Vibratory Shear Enhanced Processing)—can successfully treat tailings pond water from gold mining. VSEP overcomes the high scaling, high TDS, and complex chemistry typical of cyanide leach effluent, allowing single‑step treatment where conventional RO would normally foul.
2. How does VSEP differ from conventional RO for mining water?
Traditional RO fouls quickly on mine water due to concentration polarization, scaling, and suspended solids. VSEP eliminates these issues by oscillating the membrane at 50 Hz, creating extreme shear forces that prevent solids buildup. This allows VSEP to treat waters with high sulfate, calcium, silica, and fine particulates—streams normally considered unsuitable for membrane filtration.
3. Can VSEP remove cyanide, ammonia, nitrate, and selenium from tailings pond water?
Yes. VSEP paired with RO can remove these contaminants to below typical discharge limits. While conventional systems require multiple treatment stages (cyanide destruction, biological nitrate/selenium removal, clarifiers), VSEP produces ultrapure permeate in a single step without chemical addition.
4. What contaminants are typically found in gold tailings pond water?
Tailings pond effluent often includes:
- TDS: 2,000–6,000 mg/L
- Sulfate: 300–1,500 mg/L
- Calcium & magnesium from lime addition
- Residual metals (Cu, Zn, Fe, Al)
- Nitrogen species: ammonia, nitrate
- Cyanide breakdown products
- Fine suspended solids
5. What pretreatment is required before VSEP?
VSEP requires only minimal pretreatment:
- Removal of solids >100 microns
- Screening to prevent large debris
No flocculants, coagulants, or chemical conditioning are required for the membrane itself.
6. What recovery can VSEP achieve on tailings pond water?
Recovery depends on TDS and scaling potential but generally ranges from 50%–95% for mine water streams. During pilot testing, site‑specific recovery, flux, and membrane type are selected based on the exact TSF water chemistry.
7. Does VSEP work on high‑scaling waters like sulfate, gypsum, or silica?
Yes. VSEP is specifically designed for high‑scaling, high‑viscosity, and high‑TDS streams. The vibratory shear prevents concentration polarization, while the agitation pattern encourages precipitation away from the membrane, similar to a membrane crystallizer.
8. Has VSEP been used in mining applications before?
Yes. While gold tailings pond water has not yet been pilot‑tested, VSEP has extensive mining experience, including:
- Phosphate mine effluent
- TENORM transport water
- Precious metals recovery
- Coal slurry dewatering
- Titanium dioxide and calcium carbonate slurries
- Other tailings pond waters
Pilot testing is performed to validate performance for each new effluent type.
9. How does VSEP compare to traditional chemical/biological treatment trains?
Traditional gold mine water treatment requires:
- pH adjustment
- Coagulation/flocculation
- Clarification
- Biological treatment for N, Se, SCN
- Filtration
VSEP replaces most of these steps with one compact, automated system, reducing: - Chemical usage
- Sludge production
- Footprint
- Operator intervention
- Capital and operating costs
10. What testing is required before sizing a full‑scale VSEP system?
New Logic conducts:
- Bench testing
- Onsite pilot testing for 7–30 days
Data gathered includes flux, rejection, recovery, temperature impact, and fouling resistance. Full performance projections and membrane selection are based on pilot results.