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Effects of Jointing and Bedding Separation on Limestone Breakage At a Reduced Scale.

Authors
Larson-WC; Pugliese-JM
Source
NTIS: PB 231 297 :13 pages
Link
NIOSHTIC No.
10000810
Abstract
A study was conducted by the Bureau of Mines to provide quarry operators with information regarding (1) the effects of jointing and bedding on rock fragmentation when bench blasting in two small-scale (2.5-Ft) limestone benches and (2) the successful use of inexpensive equipment and field techniques to determine the orientation and spacing of joints and bedding separations within the quarry. Using inexpensive equipment, such as a pocket transit and steel and paper tapes, joint and bedding separations were mapped and their frequencies measured. Results from two small-scale bench blasts in the stewartville member of the Galena limestone formation showed that when the row of vertical blastholes were oblique to the vertical joint orientations, the backface expression was outlined by two relatively large triangular protrusions (joint surfaces). In this blast, part of the rock burden was unbroken. When the line of vertical blastholes paralleled a predominant joint set, all of the rock burden was broken and displaced. The thickness of fragments that had been displaced by a blast correlated with the observed bedding thickness in the bench.
Publication Date
19740101
Document Type
IH; Report of Investigations
Fiscal Year
1974
NTIS Accession No.
PB-231297
NTIS Price
A03
Identifying No.
RI 7863
NIOSH Division
TCRC;
Source Name
NTIS: PB 231 297
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