Masters Theses


"One of the most recent developments in blasting practice is that of applying the principle of short period delay electric blasting. In this type of electric blasting, instead or having all holes fire at one time, each hole or group of holes is a shot in itself. To provide a short period delay, of a few thousandths of a second, between each hole or group of holes, either millisecond (split-second) delay electric blasting caps or a suitable delayed action blasting switch may be used.

Short period delay electric blasting systems were originally developed for use by quarries in or near urban areas in order to reduce vibration and concussion. However, it early became evident that many other advantages would accrue with the use of such systems of blasting.

The advantage of split-second delay electric blasting caps for quarrying and open-pit or strip mines, as claimed by the manufacturers, can be summarized as follows:

(1) better breakage (fragmentation)

(2) controlled backbreak;

(3) helps regulate throw;

(4) cuts down complaints about noise and vibration;

(5) cuts cost on explosives and drilling.

With the success of short period delay systems in surface mining and quarrying, it was recognized that there might well be various applications of the systems to certain problems encountered in underground mining operations.

They are now being used successfully in some underground mining. Advantages of split-second delay electric blasting caps for underground mining, as claimed by manufacturers, may be summarized as follows:

(1) improved fragmentation;

(2) marked reduction of bootlegs;

(3) elimination of dynamite in the muck through prevention of "cut-offs";

(4) decreased concussion and vibration.

The purpose of this research is to evaluate the uses and advantages of the various systems of short period delay blasting used in surface and underground mining.

As part of this research a limited number of tests were made at Missouri School of Mines' Experimental Quarry to determine if it is practical to choose an optimum system or delay interval for a particular set of conditions; and a survey of the agricultural limestone industry of Missouri in regard to blasting practices was made "--Introduction, pages 1-2.


Forrester, James Donald, 1906-1979


Mining Engineering

Degree Name

M.S. in Mining Engineering


Missouri School of Mines and Metallurgy

Publication Date



vi, 78 pages

Note about bibliography

Includes bibliographical references (pages 75-77).


© 1951 Irving C. Falk, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Electric detonators -- Testing
Blast effect -- Testing

Thesis Number

T 981

Print OCLC #


Electronic OCLC #