Nabiullah,, M. and Pingua, B.M.P and jagdish, Dr. and Sinha, A. (2007) Study on Air, Water Deck in Pre-splitting And Rock Blasting in Tata West Bokaro. Indian Mining & Engineering Journal , 46 (9). pp. 52-61. ISSN 0019-5944

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Abstract

A study was conducted to evaluate the effect of air deck (pipe deck), water deck technique to control induced ground vibration in production blasting and pre-splitting at Tata west Bokaro, Colliery. Bulk explosive and shock tube initiation was normally used in mines. The study was aimed at optimization of blast parameters to enhance over all blasting efficiency in quarry by using explosive products such as dopped emulsion and emulsion mixed ammonium nitrate & fuel mixture (HANFO) with the help of air deck technique keeping in view of nearby structures. The attempts were made to improve over fragmentation and to control fly-rock within safe limits. The compressive and tensile strength of rock is less than 18.05 – 62.94 Mpa and 1.84 – 10.08 Mpa respectively. The average bench height was 8 to 14m, which was suitable for 160mm-diameter blast hole. The optimum burden and spacing was found to be 5 and 6m respectively for three rows blasting. The blast face should be kept vertical. If face is not vertical attempt should be made to make them vertical prior to deep hole blasting. The explosive should be charge as per face conditions and desire fragmentation. 100g cast booster should be used to prime bulk emulsion or HANFO at interval of 2.5 to 3.0 distances. Polythene tube of 1.0-0.8m was used as air deck. PVC pipe of 0.8m length of 100 mm diameter was found effective for air decking. Stemming column was maintained 3.0-3.5m and bottom initiation systems i.e. excel or reydet was used to avoid fly-rock. Delay time 3 to 4ms/m was found effective for hole to hole delay to reduce vibration and back break and 12.0 to 18.0ms/m delay interval was found effective to control back break. Cross cur or V cut firing system was found effective improve fragmentation in PVC pipe/air deck. Study on site casting Study was conducted to reduce bench height (16 to 18m) in single blast for satisfactory operation of shovel machine. Therefore, blast design was conducted so that 1st and IInd rows were casted 30 to 40 percent as compared to normal blast. Study on pre-splitting The aim of pre-splitting was to control ground vibration on high well side in quarry E. the diameter of holes, depth and spacing was 150mm, 17 to 18m and 1.6 to 1.7m respectively. Explosive was charged 25 to 30kg per hole. A length of 130m was pre split. The delay interval between holes was 5ms/m. pipe deck was found effective for pre-splitting.

Item Type:	Article
Subjects:	Explosive Research
Divisions:	UNSPECIFIED
Depositing User:	Dr. Satyendra Kumar Singh
Date Deposited:	14 Dec 2011 04:45
Last Modified:	14 Dec 2011 04:45
URI:	http://cimfr.csircentral.net/id/eprint/358

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