Compiled and Edited by: Dr. Nader Salek
Date: August 2026
Introduction
In many gold mines, a portion of the gold present in the ore is lost during various stages of processing and ultimately ends up in the tailings.
Therefore, the fastest route to increasing gold production is not always mine development or increasing plant capacity; rather, it is first necessary to determine exactly at which stage of the process the gold is being lost and how it can be recovered.
The goal of this plan is to establish a “maximum recovery” circuit—that is, extracting the maximum possible amount of gold from the existing feed, while controlling both capital and operational expenditures.
1. Stage One: Realistic Measurement of Gold Loss
Before making any changes to the plant, a precise mass balance must be conducted on the following streams:
- Mine feed
- Concentrate
- Final product
- Intermediate streams
- Final tailings
The grade and quantity of gold must be measured for each stream.
However, more important than the grade is determining the form and size of the gold:
- Free gold
- Very fine gold
- Gold locked within pyrite and arsenopyrite
- Gold associated with other minerals
This stage determines exactly where subsequent investment should be directed.
2. Stage Two: Recovering Free Gold
If tests confirm the presence of free gold, it must first be recovered using gravity methods.
For streams that have already passed through the plant, a pilot circuit can be designed for the tailings, and appropriate gravity equipment can be used to assess the recoverability of free gold.
The advantage of this method is that it can be tested as a side circuit without making fundamental changes to the entire plant.
3. Stage Three: Focusing on Fine and Ultra-Fine Gold
If tests show that the bulk of the remaining gold is very fine, grinding should not simply be increased.
In this situation, fine particle flotation and nanobubble technology are worth investigating.
Recent studies have shown that nanobubbles can improve the attachment of bubbles to very fine particles. A study published in 2026 reported an approximately 8 percentage point increase in concentrate recovery and a 2 g/t increase in grade for a specific gold ore sample. This result is laboratory-based and ore-dependent, and must be confirmed by testing on the mine’s own samples. (DOI)
Therefore, the practical recommendation is not the immediate installation of a large nanobubble system, but rather:
- Laboratory testing
- Pilot testing
- Comparison with the existing circuit
- Then a decision regarding industrial-scale installation
4. Stage Four: If the Gold is Locked
If it is determined that the gold is locked within the structure of sulfide minerals, the problem cannot be solved by simple separation methods.
In this case, the host mineral must first be destroyed or oxidized.
Two significant options are:
BIOX
Bio-oxidation for the pre-treatment of refractory gold concentrates is a well-established industrial technology. According to the latest information from Metso, this technology has over 30 years of commercial history and has been utilized in numerous plants. (Metso)
POX
Pressure oxidation is also a viable option for refractory ores and concentrates. Alongside BIOX and roasting, it is considered one of the main industrial routes for the pre-treatment of refractory ores. (Metso)
5. Stage Five: Treating Tailings as a New Resource
One of the most important practical actions is sampling from the current and old mine tailings.
If the amount of remaining gold is economically significant, a standalone “tailings reprocessing” project can be defined.
Recent studies have also highlighted gold tailings reprocessing as an important economic and environmentally friendly route. However, the cost of chemicals, scalability, and the specific characteristics of each tailings stream must be examined separately. (ScienceDirect)
6. Proposed Circuit for Maximum Recovery
The final circuit should not be identical for all mines, but a studyable structure could be as follows:
Ore → Controlled Crushing → Grinding → Gravity Separation (Free Gold) → Flotation → Nanobubble Flotation (for fine fraction) → BIOX or POX Pre-treatment (if refractory) → Leaching → Gold Recovery from Solution → Smelting and Doré Production.
Concurrently:
Tailings → Sampling and Mineralogy → Size Classification → Gravity Separation → Flotation/Nanobubbles → Residual Leaching (if economically justified).
7. Capacity Increase: The Final Stage
Increasing plant capacity should only be undertaken after recovery has been improved.
If a plant with low recovery merely increases its throughput, it may end up transferring a larger volume of recoverable gold to the tailings.
Therefore, the main project metric should be:
Recovered gold per ton of feed
And not simply:
More tons of feed per day.
8. Proposed Implementation Program
To initiate a real project, the work can be carried out in four stages:
Stage One: Diagnosis
Sampling from feed, concentrate, intermediate streams, and tailings + grade analysis and mineralogy.
Stage Two: Testing
Gravity, flotation, nanobubble, and, if necessary, leaching or pre-treatment of refractory ore tests.
Stage Three: Pilot
Implementing the selected technology on a limited scale and measuring the actual recovery.
Stage Four: Investment
Only after the recovery increase has been proven and the economics calculated should circuit development and capacity expansion proceed.
Conclusion
The real solution for “maximum gold recovery” is not the use of a single technology.
The lost gold in the tailings must first be identified; then, based on its form and size, the most appropriate combination of technologies should be selected.
In one project, the gravity method may have the greatest impact; in another, flotation and nanobubbles; and in refractory ore, BIOX or POX may play the primary role.
Therefore, the best investment is not necessarily buying the most advanced equipment; rather, it is pinpointing where the gold is being lost and targeting exactly that area.
This approach can enable an increase in gold production without relying on a proportional increase in mine extraction, by enhancing recovery and reprocessing resources already present in the plant and tailings.
Dr. Nader Salek
Consultant & Trade Facilitator
GHAVFEL AL-LOLO Company (GHLOLO)
A Subsidiary of Salek Trading Group
Website: www.Ghloloco.com
Email: info@Ghloloco.com
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