The rock extracted from Soutra Mains Quarry is classed as a Greywacke, which is part of the Gritstone Rock Group. This is a particularly durable rock being suitable for use in the manufacture of coated roadstone (tarmac) and all types of concrete products. 

 

 

 

 

 

Stripping
To gain initial access to the rock any soil, subsoil and any other types of soft dirty material, which covers the top of the rock, must first be removed. This is called stripping or "muck shifting" and is usually carried out with large excavators, wheeled loading shovels and dump trucks. This material is then used to landscape the quarry or is stored for restoration uses at a later date.

 

 

Drilling & Blasting
With the top of the rock surface now clean and levelled off it can now be drilled in preparation for blasting of the rock face. The rock drilling is carried out by a pneumatically powered drill rig, which traverses on caterpillar type tracks. This machine drives drill tubes vertically into the rock face to a pre-determined depth and angle. These drill holes are equally spaced apart in single, double or treble rows of some 10-30 holes.
These drill holes are then carefully loaded with sausage type explosive pills which can only be detonated with a high electrical current in a controlled and safe manner. This blast can release up to 35,000 tonne of large boulder-sized rocks.

 

Primary & Secondary Crushing
These large boulder-sized rocks are then lifted by the face excavator and cast into the primary crusher where they are crushed between two large steel jaws into smaller stones prior to being conveyed into the secondary cone crusher which again further reduces the size of stone. Any large boulder sized rocks which are initially too large for this process are first broken in half with an excavator mounted hydraulic hammer.

This primary & secondary crushing process reduces the boulder-sized rocks down to rocks the size of a tennis ball.

Tertiary Crushing and Screening
This tennis ball sized rock is then lifted by a loading shovel and processed through a smaller cone crusher which reduces the rock to its finished product sizes. This smaller crushed material is then passed over a series of screens which segregate them into the individual sizes of 40mm, 28mm, 20mm, 14mm, 10mm, 6mm and whin dust.


Product Uses
These single sized aggregates or blends of such are used in the manufacture of concrete, tarmac, building blocks, bricks, roof tiles, slabs which are all key constituents in the building of roads, railways, airports, hospitals and houses etc.