Britain’s diverse geology means the country has a variety of mineral resources in the ground. Each has unique properties and can be quarried and processed for a wide variety of essential uses.
However, these geological resources are not evenly distributed across the country and must be transported from where they are extracted to where they are needed.
For example, imagine drawing a diagonal line across a map of Britain from the River Exe in the south west of England to the Tees estuary in the north east. The resources to the north of this line are dominated by hard rock such as limestone and granite. To the south, resources are primarily sand and gravel. Sand and gravel can also be found on the seabed and are landed at various ports around the country for processing.
This means that millions of tonnes of mineral products such as aggregates travel around the country by road, rail, river and sea. Transporting mineral products as efficiently as possible to meet the country’s demand is one of the industry’s biggest logistical challenges.
Before any quarrying can begin there’s a long and complex process to identify potential mineral resources and secure the right permissions and licences. This applies whether the mineral is in the ground or beneath the sea. The same applies for proposals for other mineral products activities such as concrete plants, rail depots or recycling facilities.
It’s a process that can take years, but it helps to ensure that the country’s mineral resources are managed and monitored, with full consideration for the environment, local communities and subsequent use of the land after quarrying.
There are more than 2,000 quarries and associated production sites across Great Britain – from quarries and cement works to concrete factories and asphalt plants. Each site is different depending on the type of material, the location of the site, the processes required, the size of the market they supply and many other factors.
Mineral product operations can therefore vary enormously, from a typical ready-mixed concrete plant which can occupy the space less than half a football pitch to a cement works which can cover an area the size of several hundred football pitches. The length of time individual sites work will also be dependent on many factors, ranging from a few years through to many decades.
Broadly speaking, there are two types of quarry – (1) hard rock and (2) sand & gravel:
Hard rock quarries produce aggregates such as limestone and granite. They are usually large and can be very deep – depending on the geology – and the rock will be blasted and dug out at multiple different levels known as ‘benches’.
Sand and gravel quarries are shallower than rock quarries because the mineral deposits are usually around 5 metres deep. No blasting is required as the mineral has already been broken down by the action of ice and water over thousands of years.
The key processes in most quarries are as follows:
Alongside aggregates which are quarried on land, around a fifth of the country’s aggregate demand is met by dredging sand and gravel from the sea bed around the British Isles. Aggregates vessels use a giant vacuum pump to remove sediment from the seabed at locations around the coast of England and Wales.
This carefully regulated and managed process only allows dredging to take place in defined licence areas to minimise the risk of harm to marine life on the sea bed or impacts on other marine users, and to allow recovery of previously dredged areas.
The dredged sand and gravel is landed at wharves in ports around the British coastline where it is unloaded, washed and processed in the same way as quarried sand and gravel.
Quarrying is one of the few ways that archaeologists and palaeontologists can quickly examine large areas of land to uncover evidence of the history. Because of this, many incredible discoveries have been made as a result of mineral extraction, from remains of everything from Roman villas to woolly rhinos and mammoths.
It is industry practice to give access to teams of archaeologists where interesting remains are revealed. MPA members have spent millions of pounds supporting archaeological digs on their sites and at any one-time hundreds of hectares of quarry land are being investigated by teams of archaeologists.
The Mineral Products Association (MPA) is the trade association for the aggregates, asphalt, cement, concrete, dimension stone, lime, mortar and silica sand industries.