Extraction of gypsum, how we do it
At Bantycock Quarry we extract gypsum that lies close to the surface.
The gypsum is found in a number of beds (or seams) separated by a type of mudrock (referred to as interburden) and also covered by clay/mudrock (known as overburden) and soils. To be able to access the gypsum, we need to remove the soils, overburden and interburden.
The process for extracting the high-purity gypsum and processing it into plaster products is outlined here and explained in further detail on the other tabs on this page.
The site preparation works for each part of the site are the same:
Each stage is discussed in more detail below.
These soils are removed using an excavator machine (see below), before being loaded into a dump truck and transported elsewhere within the site to create screening ‘bunds’ or raised areas of land.
|Soil stripping is supervised by an archaeological specialist.
It is important that we keep these soils to use at a later date when the site is restored.
We work with archaeological experts to carry out investigations throughout the site usually one year in advance of starting gypsum extraction in a new part of the quarry.
Archaeological recording has been ongoing for more than 15 years. It has revealed Iron Age and Roman remains, which are taken away to be recorded and then either put in storage or displayed.
Once the soils have been stripped and archaeological investigations completed, we can remove the overburden.
|The thickness of overburden at the quarry is approximately 28 metres. The overburden is removed using an excavator machine and loaded onto dump trucks.
Where possible, overburden is placed directly in a previously worked area of the quarry as part of progressive restoration work. Where this is not possible, we place it into store on the edge of the workings until it is required for restoration
The use of controlled explosives to create a series of cracks in the rock and loosen the harder deposits of gypsum is a necessary part of the operations at Bantycock Quarry.
|Blasting is limited, as it only needs to ‘fracture’ the gypsum so that it can be lifted by excavator to the processing area.
Of the seven ‘seams’ or layers of gypsum at Bantycock, only the top two are blasted due to their thickness before being removed by excavators. The remaining five gypsum seams are removed by excavators only.
All blasting operations follow recognised best practice and are designed and carried out by highly qualified personnel. Blasting only occurs within set times of the day (1:30 - 3:30pm Monday – Friday). For more detail about our blasting operations please click here.
We extract gypsum at an average production rate of 400,000 tonnes per year, which is dependent upon the demand from Saint-Gobain Formula's Jericho Works (adjacent to the quarry), and British Gypsum’s manufacturing plants at East Leake (Nottinghamshire) and Barrow (Leicestershire).
The extracted gypsum is loaded into dump trucks and transported to the processing plant.
Example of a typical blast
We carry out a small amount of gypsum processing using plant located within the quarry void (below ground level).
|The plant occupies an area of approximately 150 metres x 100 metres and has a maximum height of approximately seven metres.
Once in the processing area, any pieces of gypsum that are too large to pass through the plant are broken down into smaller pieces using a hydraulic breaker, known as a ‘pecker’.
Gypsum is then passed through the processing plant to clean, crush and segregate it into different quality grades, dependent on the customer requirements. The processing lines are controlled by an environmental permit which is issued and monitored annually by Newark and Sherwood District Council.
Once the gypsum has been processed, it is either transferred across Staple Lane via a dedicated crossing point to Saint-Gobain Formula (Jericho Works), or transported to one of British Gypsum’s manufacturing sites using heavy goods vehicles (HGVs).
|Once loaded, all HGVs are covered with a sheet and go through a wheel wash before leaving the site to prevent dust emissions from the processed gypsum during transportation.
We progressively restore the quarry as areas become available following the completion of gypsum extraction operations.
|A recent example of restoration at the quarry is shown here. We planted this 25 acre part of the site in 2017-18 with 29,500 trees. The trees were specially selected to create a mix of wet woodland and native woodland species and provide important habitat for birds and wildlife. We plan to extend the tree planting woodland area further as other parts of the site are regenerated.