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Закрити книгу / close this bookSpecial Public Works Programmes - SPWP - Stone Paving-Blocks - Quarrying, Cutting and Dressing (ILO, UNDP; 1992; 60 pages)
Перегляд документу / View the documentIntroduction
Вiдкрити папку i переглянути змiст / Open this folder and view contents1. The quarry
Закрити папку / close this folder2. QUARRYING
Перегляд документу / View the documentQuarrying methods
Перегляд документу / View the documentQuarrying using a crowbar
Перегляд документу / View the documentChannelling
Перегляд документу / View the documentMaking wedge-holes
Перегляд документу / View the documentQuarry wedges
Перегляд документу / View the documentCutting a block with wedges and a sledgehammer
Перегляд документу / View the documentPlug and feathers
Перегляд документу / View the documentQuarry equipment and tools
Перегляд документу / View the documentUse of explosives in stone quarrying
Перегляд документу / View the documentBlock-splitting using black powder
Перегляд документу / View the documentCalmmite
Вiдкрити папку i переглянути змiст / Open this folder and view contents3. HANDLING THE BLOCKS
Вiдкрити папку i переглянути змiст / Open this folder and view contents4. SECONDARY CUTTING AND DRESSING
Вiдкрити папку i переглянути змiст / Open this folder and view contents5. STORING AND TRANSPORTING STONE PAVING BLOCKS
Перегляд документу / View the documentBack Cover
 

Block-splitting using black powder

First, a groove (along which the rock will be split) is made, following the rock's cleavage (direction of cracks).

Next, blasting holes are made along the groove, either using the hammer action of a rock drill (fitted with a chisel end) or a crowbar if the rock is soft (sandstone or limestone).


Boring with a 2-metre crowbar

Average productivity rate in sandstone: 1.5 work-days per linear metre.

Boring in soft rock

In hand drilling soft rock such as sandstone, water is used to free the hole of rock dust and thereby facilitate boring.


Rubber ring to prevent water from splashing out whilst boring.

The number of holes depends on the size of the rock mass to be split Next explosive cartridges are placed at the bottom of the holes. The number of cartridges per hole is determined by the strength required of the explosion, which in turn also depends on the size of the block to be split.


Blasting preparation (the holes are sealed while waiting for the explosive charges to be put in place)

Black powder is primed using a slow fuse which transmits a flame at the rate of 1 metre in 90 seconds. Once the primed cartridges are in place in the holes, the holes are packed with clay or sand.

The fuse is lit by the certified blasting officer only after all quarry workers have been guided to a safe location.

The shock wave caused by the explosion will be guided by the groove.

Safety:

Use of explosives is dangerous. This means that safety precautions must be taken.

All stipulations contained in national legislation and regulations, as well as recognised guidelines on the use of explosives, must be respected. Rules regarding the transport, storage and use of explosives and detonators aim at protecting people and property against bodily or material harm. Only holders of blasting certificates can be authorised to handle and use explosives.

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