The process of raking out stones from natural rock beds is known as quarrying, the term quarry is used to indicate the exposed surface of natural rocks, the difference between a mine and a quarry should be noted.
In the case of a mine, the operations are carried out under the ground at great depth whereas, in the case of the quarry the operations are carried out at ground level in an exposed condition.
Stones are natural rock masses or as layers on the surface.
Factors consider while deciding the location of a quarry site as follows:
- Availability of sufficient quantity of desired quality stones.
- It should have proper transport facilities.
- Cheap local labor.
- Problems associated with rainwater drainage.
- Location of permanent structures in the locality and site to forbid dumping.
Methods of Quarrying of stone:
This quarrying method is appropriate for costly, soft and stratified rocks such as sandstone, limestone, laterite, marble and slate.
Holes about 10–15 cm deep, at a distance of about 10 cm are made perpendicular to the rock.
Steel pins and wedges or plugs (conical wedges) and feathers are inserted into them, these plugs are then hit together with a sledge hammer.
Heating is best suited for heating small, thin and regular blocks of stones from rocks such as granite and gneiss.
In a small area, the pile of fuel is piled on the rock surface and fired.
Two consecutive layers of rock break apart due to uneven expansion of the two layers, the loose rock part is broken into pieces of the desired shape and removed with the help of pick-axes and crow-bars.
The obtained stone blocks are very appropriate for rough particles, while the intermediate layers should be separated from the highest and backside layers.
In such a case, the intermediate layer is electrically heated and the expansion separates from the other two layers.
A quarrying of stone has a rough surface that is prepared to obtain a fixed and regular shape.
The dressing of the stones is finished immediately after the quarry and before the season to acquire much less weight for transport.
If the rock surface contains cracks of fissures then wedging technique is adopted.
Metal wedges or points are pushed by means of such cracks via a hammer, blocks of stones are then shifted, and eliminated with the help of suitable devices.
If natural cracks are usually not available, artificial cracks are formed, this method is adopted for rocks which might be comparatively smooth.
In this method, the explosive is adopted of quarrying to transform rocks into small pieces used when hand rocks having no fissures or cracks are to be damaged down into small pieces.
Stone obtained by blasting is normally small in size, and they are used as ballast in railway, aggregate for concrete road metal, etc.
The following instruments are required within the process of blasting like a dipper, jumper, priming needle, scraping spoon, and tamping bar.
Tools for Quarrying of Stone:
The following tools are required within the blasting process as follows:
It is used to drill a gap to the required depth.
It is used to make blast holes, more effective in boring vertical holes round.
(3) Priming needle:
It is used for retaining holes when the tamping is being tapped as a skinny copper rod pointed at one end and a loop is provided on the other end for handling.
After the hole has been filled with explosives, it is filled with tempered earth and this needle is placed in the center so that a path is developed for the insertion of the fuse due to explosion by its removal or extraction.
(4) Scrapping Spoon:
It is used to remove the crushed stone dust from blast holes.
Within the type of an iron rod with a round plate attached at one end and a loop is provided on the different end to facilitate its handling.
(5) Tamping Bar:
Tamping Bar is used to ramp or tamp the material while refilling blast holes.
It is in the form of a heavy brass rod of 10 mm to 15 mm diameter and it tapers slightly at the ends.
Also read: Dressing of Stones & Stone Masonry
Stone quarrying is the surface extraction of a wide range of minerals and extraction is the general term for obtaining minerals from the continental crust of the earth.
Large surface operations are called open-pit mining while extraction of minerals below 1 km below the surface is called underground mining.