Dilution occurs when waste material is mixed in with the ore during the mining phase and fed to the processing plant. The discrimination between ore and sub-economic dilution material is the site – and process specific cut-off grade (Dilution – SIX-S GmbH, n.d.).
What are the types of dilution?
Internal dilution and external dilution are the two forms of dilutions that might occur in a mining block during operation. Waste or even low-grade ore (ore below cut-off) that cannot be mined separately and is eventually mined with the ore in the mining block is referred to as internal dilution. Waste outside of the orebody that is mined alongside the ore inside the mining block is referred to as external dilution.
What are the impacts of dilution?
Most people who are involved in mine planning are aware of the significant economic impacts of dilution depending on what dilution factor is applied and how it is actually applied to the block model. To bring everyone to speed, one of the main consequences of dilution is the increase in ore tonnage sent to the plant with a reduction of mill feed grade. Lower feed grade translates to lower mill recovery, and this accompanied by increasing processing costs translates to less income. Dilution also increases the economic cut-off of the project. For marginal grade ore, dilution may reduce the grades in a block to a degree that it becomes uneconomic to be processed. This is precisely why it is important to think carefully about the approach that you are going to use to model dilution on your block model ((5) The 4 Ws of Dilution in Open Pit Planning | LinkedIn, n.d.).
How to overcome dilution in mining?
According to ((5) Managing Dilution in Mining Operations | LinkedIn, n.d.), here are some strategies to effectively control dilution:
Optimized Mine Design: develop detailed mine designs that consider the geological characteristics of the orebody. Implement bench heights and slope angles that minimize ore loss and waste material movement.
Geological Modelling and Ore Body Knowledge: improve the accuracy of geological models and orebody knowledge to precisely delineate the boundaries of the ore and waste zones.
Drill and Blast Techniques: utilize precision drilling and blasting techniques to minimize damage to the orebody and surrounding rock, reducing dilution during the blasting process.
Blasting Design: design the blast patterns to avoid excessive fracturing and over-break, thereby minimizing dilution caused by blasting.
Fragmentation Analysis: conduct regular fragmentation analysis to assess the effectiveness of blasting and adjust techniques as needed to reduce dilution.
Grade Control: implement effective grade control procedures to accurately determine the grade of the ore being mined, reducing the risk of dilution due to blending of high- and low-grade materials.
Image rights: Paul Tim Wilhans
Reference
(5) Managing dilution in mining operations | LinkedIn. (n.d.). Retrieved April 15, 2025, from https://www.linkedin.com/pulse/managing-dilution-mining-operations-arash-pashapour/
(5) The 4 Ws of dilution in open pit planning | LinkedIn. (n.d.). Retrieved April 15, 2025, from https://www.linkedin.com/pulse/4-ws-dilution-open-pit-planning-thabang-maepa/
Dilution – SIX-S GmbH. (n.d.). Retrieved April 15, 2025, from https://www.six-s.com/knowledge-base/article/dilution/
