Mining Overburden (OB) to Sand
Converting mine waste dumps into recycled sand and aggregates for construction.
Overburden (OB) is the rock or soil layer removed to access the ore being mined; unlike tailings, it contains no toxic components. Where OB consists of weathered sandstone or its sludge, CFlo plants recover sand by washing the overburden and separating particles through sedimentation and decantation, producing recycled sand and aggregates for construction.
What is overburden?
During any mining operation, the rock or soil layer that must be removed to access the ore being mined, and which does not contain toxic components, unlike tailings, is called overburden. It is also referred to as spoil or waste.
The hazards of overburden dumps
Along with occupying huge land areas, overburden dumps pose a serious threat to nearby areas, impacting flora and fauna. The dumps are not stable: they create cracks and collect rainwater, presenting a risk of flooding and mass erosion to surrounding areas.
People living near these dumps often use the land for agriculture and farmland. Land used as pasture and for agriculture shows high concentrations of nickel and chromium in locations close to certain kinds of mines, and heavy metals are believed to have already entered the food chain due to the overburden menace. The consequences are felt in the health and social life of inhabitants, and may pass on to future generations.
Recycling overburden into sand
Depending on the nature of the mine, overburden can consist of materials such as weathered sandstone or its sludge. Sand particles are recovered by washing the overburden and separating them through sedimentation and decantation. The recycled sand and aggregates then serve a range of construction applications.
The processing phases
Each plant CFlo designs includes a combination of processing phases matched to your specific requirements:
- Feeding and pre-screening
- Metal removal
- Aggregate scrubbing
- Contaminant removal
- Sand washing
- Aggregate sizing
- Primary stage water treatment
- Sludge management
The related CFlo platform for OB-to-sand duty is the Reurban wet processing system.
Frequently asked questions
What is mining overburden?
Overburden, also called spoil or waste, is the rock or soil layer removed during mining to access the ore beneath. Unlike tailings, it does not contain toxic process components, which is exactly why it can be recycled into construction sand rather than left in waste dumps.
Can overburden really be converted into sand?
Yes, where the overburden consists of materials such as weathered sandstone or its sludge. CFlo plants wash the overburden and recover sand particles through sedimentation and decantation. The recycled sand and aggregates have a range of uses across construction applications.
Why are overburden dumps a problem?
They occupy huge land areas and threaten surrounding flora and fauna. The dumps are unstable, crack and collect rainwater, creating flooding and mass erosion risks. Near certain mines, pasture and farmland show high nickel and chromium concentrations, and heavy metals are believed to have entered the food chain.
What processing stages does an OB-to-sand plant include?
Each CFlo plant combines phases to suit the feed: feeding and pre-screening, metal removal, aggregate scrubbing, contaminant removal, sand washing, aggregate sizing, primary stage water treatment and sludge management. The exact configuration depends on the nature of your overburden and product requirements.
What can recycled overburden sand be used for?
The recycled sand and aggregates recovered from overburden washing serve a variety of construction applications. For mine operators, this converts a liability that occupies land and creates environmental risk into a saleable product, while reducing pressure on natural sand sources.
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