We take many things in the material world for granted, not realising or appreciating their presence or value. Construction materials that make up the material world around us come into this unconscious, “invisible” category. Though you see buildings, roads, footpaths and bridges every day, it’s almost certain that you have never thought about what the materials are, what they are made of, or where they come from. The vast bulk of our built environment is formed from raw materials won from the earth by the extractive industries. Without the raw materials with which to build houses, hospitals, schools, factories, roads, etc., life would certainly be more basic and less comfortable than we presently experience.
Stone quarrying is the multistage process by which rock is extracted from the ground and crushed to produce aggregate, which is then screened into the sizes required for immediate use, or for further processing, such as coating with bitumen to make bituminous macadam (bitmac) or asphalt.
The process begins with a detailed three-dimensional survey of the quarry face. This allows the explosives engineer to design the blast and to plot where the shot holes should be drilled so that the blast can be carried out safely and efficiently. The survey will show if there are any bulges or hollows in the face. A bulge will need more explosive than normal to ensure that it is completely fragmented and not left in place in the face. Hollow areas require less explosive than normal. The placement of explosives is professionally planned to ensure that the required fragmentation of the rock is achieved with the minimum environmental impact.
After the face profiling survey, the drilling contractor arrives. Using an air operated drilling rig, he drills the number of shot holes required, at the marked spots corresponding to the whole positions on the blast design, at the angles and depths required.
After the shot holes have been drilled, they are surveyed to check that they correspond to the blast design and the two surveys are combined to allow the blast engineer to work out how each shot hole is filled with explosives.
On the day of the blast, the explosives are delivered and taken to the site of the blast. Detonator cord is placed in each hole and the holes are then loaded with high explosives to within a few metres of the top. The remaining depth is “stemmed” with quarry dust or fine aggregate. The site is cleared. Sirens are sounded to make sure that everyone nearby is warned. The detonators are connected to the electric trigger wire and the circuit is checked. A final safety check is carried out and only when the final all clear is given does the shotfirer set off the explosives. A single blast can fragment up to 20,000 tonnes of rock.
After the blast, the face and shotpile (sometimes called the muck-heap) are inspected to check that all the shot holes have fired correctly. The face shovel or loader then tidies up the shotpile and starts to load the dumper trucks that take the rock to the crusher. Boulders which are too big to go through the crusher are set to one side for secondary breaking at a later date. Secondary breaking is typically done using a hydraulic digger fitted with a rock hammer, though crawler cranes with steel drop-balls may be used in some quarries.
Crushing can be done in three or four stages, primary (first stage), and secondary (second stage), tertiary (third stage) and, in some quarries, a quaternary (fourth stage). Crushed rock, or product, is transported along the process line on conveyor belts or down chutes.
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Stone quarry plants and stone processing equipment manufacturer
We take many things in the material world for granted, not realising or appreciating their presence or value. Construction materials that make up the material world around us come into this unconscious, “invisible” category. Though you see buildings, roads, footpaths and bridges every day, it’s almost certain that you have never thought about what the materials are, what they are made of, or where they come from. The vast bulk of our built environment is formed from raw materials won from the earth by the extractive industries. Without the raw materials with which to build houses, hospitals, schools, factories, roads, etc., life would certainly be more basic and less comfortable than we presently experience.
Stone quarrying is the multistage process by which rock is extracted from the ground and crushed to produce aggregate, which is then screened into the sizes required for immediate use, or for further processing, such as coating with bitumen to make bituminous macadam (bitmac) or asphalt.
The process begins with a detailed three-dimensional survey of the quarry face. This allows the explosives engineer to design the blast and to plot where the shot holes should be drilled so that the blast can be carried out safely and efficiently. The survey will show if there are any bulges or hollows in the face. A bulge will need more explosive than normal to ensure that it is completely fragmented and not left in place in the face. Hollow areas require less explosive than normal. The placement of explosives is professionally planned to ensure that the required fragmentation of the rock is achieved with the minimum environmental impact.
After the face profiling survey, the drilling contractor arrives. Using an air operated drilling rig, he drills the number of shot holes required, at the marked spots corresponding to the whole positions on the blast design, at the angles and depths required.
After the shot holes have been drilled, they are surveyed to check that they correspond to the blast design and the two surveys are combined to allow the blast engineer to work out how each shot hole is filled with explosives.
On the day of the blast, the explosives are delivered and taken to the site of the blast. Detonator cord is placed in each hole and the holes are then loaded with high explosives to within a few metres of the top. The remaining depth is “stemmed” with quarry dust or fine aggregate. The site is cleared. Sirens are sounded to make sure that everyone nearby is warned. The detonators are connected to the electric trigger wire and the circuit is checked. A final safety check is carried out and only when the final all clear is given does the shotfirer set off the explosives. A single blast can fragment up to 20,000 tonnes of rock.
After the blast, the face and shotpile (sometimes called the muck-heap) are inspected to check that all the shot holes have fired correctly. The face shovel or loader then tidies up the shotpile and starts to load the dumper trucks that take the rock to the crusher. Boulders which are too big to go through the crusher are set to one side for secondary breaking at a later date. Secondary breaking is typically done using a hydraulic digger fitted with a rock hammer, though crawler cranes with steel drop-balls may be used in some quarries.
Crushing can be done in three or four stages, primary (first stage), and secondary (second stage), tertiary (third stage) and, in some quarries, a quaternary (fourth stage). Crushed rock, or product, is transported along the process line on conveyor belts or down chutes.