Crushing Techniques of Rock

Crushing Techniques of Rock 

 

From time immemorial holes have been dug in the ground with chisels, hammers,

shovels and pickaxes. In some ruins of ancient people, deer horns were unearthed, which were probably used as pickaxes. In around the 8th century BC, people in today’s

Persia started construction of irrigation canals, which were called “qanat”, using pickaxes and shovels. The qanatsran without supports for 5 to 10 km and sometimes  went as far as 70 km because the route was chosen following the ground firm enough

for nonsupport excavation. Tunnels for military roads or water supply were also built in Roman days, by manual digging. When they encountered hard rock, they tried to slacken the rock by heating it up with fire and cooling it down with water. After

gunpowder was invented, it was used to explode the rock into pieces, although it was in the latter half of the 19th century that modern blasting technique was developed with the invention of dynamite and development of rock drills

 Improvement of machines to dig tunnels was accelerated when the Industrial Revolution promoted expansion of the railroad network and the construction

of long tunnels for railroad over the Alps was started. Alfred Nobel invented dynamite in 1866 and theblasting cap in 1867. Improvement of rock drills started in the early part of the 19th century with a rotary drill using steam developed by Richard Trev

ithick in 1813, and ahammer drill by the Singer Brothers in 1838.

Browton made use of compressed air in1844, and a compressed air hammer drill that rotates a chisel to hit and break rock was then developed by Fowl in 1851. In 1861, Germain Sommeiller started to use improved drilling machines and he built the Mont Cenis tunnel (Figure 1) in the Alps between italy and France in 1870. In 1897, J. G. Rheiner invented the “water liner” method, in which compressed air is sent through hollow steel chisels to the drilled hole bottom and blow off crushed muck to remove. Combined use of the improved rock drills and dynamite led the construction of the Simplon Tunnel to its completion, a 20 km long transalpine tunnel connecting Italy and Switzerland, in 1905.The dawn of the 20th century saw the debut of a jumbo, which is equipped with many large compressed air rock drills. In 1970, hydrauic rock drills emer ged, which provide enhanced drilling performance with higher pressure and greater hammering rotation than those of compressed air drills. The latest models of rock drills are excellent invarious functions as well as in improved performance of drilling. Some are equipped with angle sensors and hydraulic sensors to
ensure parallel drilling, accuracy in positioning and setting of angles. Computer-aided jumbos (Figure 2) equipped with anautomatic drilling management system have also been developed and widely used due
to improvement of the automation techniques.