US3687075A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modified presplitting technique
Assignee: Ireco Inc
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Filing: 1970-12-11
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Granted: 1972-08-29
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Expires: 1990-12-11
Abstract
Abstract A presplitting method is provided in which the blasting agents in alternate holes and interjacent holes of a blasting hole array are connected together to form two separate blasting circuits. The blasting charges in each blasting circuit are detonated simultaneously with a preestablished interval between blasting of the charges in each circuit. The combination of oppositely directed forces resulting from detonation of the blasting charge in two alternate holes causes compressive stress at an interjacent hole at the time of detonation of a blasting charge in the interjacent hole resulting in better presplitting with reduced noise and vibration.
Inventors
- 👤 Fred A Fritz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:46
CPC Classifications
F; F42; F42D; F42D1/00; F42D1/04; F42D1/045; F42D1/05; F42D1/055
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
189 words
A method of presplitting a rock formation comprising: a. forming a series of holes spaced a substantially constant distance apart along a desired presplit line, b. charging each hole with a blasting agent, c. connecting the blasting agent of alternate holes to initiator means for simultaneously initiating the blasting agent of each alternate hole, said connection forming a first blasting circuit, d. connecting the blasting agent of interjacent holes to initiator means for simultaneously initiating the blasting agent of the interjacent holes and forming a second blasting circuit, e. activation of the initiator means for the first and second blasting circuits at a predetermined time interval, said time interval between activation of the initiator means of the first and second blasting circuit being substantially equal to the shock transit time established for the rock formation between adjacent holes and generated by detonation of a like blasting agent to the blasting agent charged to the holes, whereby the blasting agents in the first blasting circuit are detonated simultaneously and the second blasting circuits are detonated simultaneously at the predetermined time interval, presplitting the rock formation along the desired presplit line.
Claim 2
Independent Claim
189 words
A method of presplitting a rock formation comprising: a. forming a series of holes spaced a substantially constant distance apart along a desired presplit line, b. charging each hole with a blasting agent, c. connecting the blasting agent of alternate holes to initiator means for simultaneously initiating the blasting agent of each alternate hole, said connection forming a first blasting circuit, d. connecting the blasting agent of interjacent holes to initiator means for simultaneously initiating the blasting agent of the interjacent holes and forming a second blasting circuit, e. activation of the initiator means for the first and second blasting circuits at a predetermined time interval, said time interval between activation of the initiator means of the first and second blasting circuit being substantially equal to the shock transit time established for the rock formation between adjacent holes and generated by detonation of a like blasting agent to the blasting agent charged to the holes, whereby the blasting agents in the first blasting circuit are detonated simultaneously and the second blasting circuits are detonated simultaneously at the predetermined time interval, presplitting the rock formation along the desired presplit line.
Claim 3
Independent Claim
184 words
A method of presplitting a rock formation comprising: a. forming a series of holes spaced a substantially constant distance apart along a desired presplit line, b. charging each hole with a blasting agent, c. connecting the blasting agent in each hole to an electrically activable initiator means for initiating said blasting charge, d. electrically connecting the initiator means of each alternately spaced hole in parallel forming a first blasting circuit and electrically connecting the initiator means of each interjacent hole in parallel forming a second blasting circuit, E. connecting the first and second blasting circuits to blasting machine, f. activating discharge of current from the blasting machine into the first and second blasting circuits at a time interval substantially equal to the shock transit time established for the rock formation between adjacent holes generated by detonation of a like blasting agent to those in each hole whereby the blasting agents of the first blasting circuit are detonated simultaneously and the blasting charges of the second blasting circuit are detonated simultaneously at the predetermined time interval splitting the rock formation along the desired presplit line.
Claim 4
Independent Claim
184 words
A method of presplitting a rock formation comprising: a. forming a series of holes spaced a substantially constant distance apart along a desired presplit line, b. charging each hole with a blasting agent, c. connecting the blasting agent in each hole to an electrically activable initiator means for initiating said blasting charge, d. electrically connecting the initiator means of each alternately spaced hole in parallel forming a first blasting circuit and electrically connecting the initiator means of each interjacent hole in parallel forming a second blasting circuit, E. connecting the first and second blasting circuits to blasting machine, f. activating discharge of current from the blasting machine into the first and second blasting circuits at a time interval substantially equal to the shock transit time established for the rock formation between adjacent holes generated by detonation of a like blasting agent to those in each hole whereby the blasting agents of the first blasting circuit are detonated simultaneously and the blasting charges of the second blasting circuit are detonated simultaneously at the predetermined time interval splitting the rock formation along the desired presplit line.
Claim 5
Dependent Claim
25 words
The method of claim 2 wherein the electrically activable initiator means is a blasting cap and the blasting cap is positioned fully within each hole.
Claim 6
Independent Claim
158 words
A system for presplitting a rock formation comprising: a. a plurality of blasting holes in a blasting hole array spaced a substantially constant distance apart along a desired presplit line, b. a blasting agent positioned within each blasting hole, c. electrically activable initiator means for initiating detonation of each blasting agent, d. a first blasting circuit comprising a parallel connection of initiator means in alternate blasting holes in the blasting hole array, e. a second blasting circuit comprising a parallel connection of initiator means in interjacent blasting holes of the blasting hole array, and f. an electrical energy supply means capable of supplying sufficient energy to the first and second blasting circuits at a predetermined time interval equal to the shock transit time of the rock formation to activate the initiator means for each blasting agent whereby the blasting agents in the first and second blasting circuits are detonated at the predetermined time interval presplitting the rock formation.
Claim 7
Independent Claim
158 words
A system for presplitting a rock formation comprising: a. a plurality of blasting holes in a blasting hole array spaced a substantially constant distance apart along a desired presplit line, b. a blasting agent positioned within each blasting hole, c. electrically activable initiator means for initiating detonation of each blasting agent, d. a first blasting circuit comprising a parallel connection of initiator means in alternate blasting holes in the blasting hole array, e. a second blasting circuit comprising a parallel connection of initiator means in interjacent blasting holes of the blasting hole array, and f. an electrical energy supply means capable of supplying sufficient energy to the first and second blasting circuits at a predetermined time interval equal to the shock transit time of the rock formation to activate the initiator means for each blasting agent whereby the blasting agents in the first and second blasting circuits are detonated at the predetermined time interval presplitting the rock formation.
Claim 8
Dependent Claim
24 words
The system of claim 4 wherein the electrically activable initiator means is a blasting cap, said blasting cap being positioned fully within each hole.
Claim 9
Dependent Claim
426 words
The blasting system of claim 5 wherein the electrical energy supply means is a blasting machine having in combination: a. at least two firing circuits connected in parallel, each firing circuit having a firing capacitor charged through a resistance means, a transformer having a primary coil and a secondary coil and a first silicon controlled rectifier, one lead of the primary coil being connected at the junction of the firing capacitor and the resistance means and the other lead of the primary coil being connected to the anode of the first silicon controlled rectifier and one lead of the secondary coil being connected to the cathode of the first silicon controlled rectifier and the other lead of the secondary coil being connected to the gate of a second silicon controlled rectifier, said firing capacitor being charged when a first D.C. power source is positioned conductive between the firing capacitor and a first switch means; b. at least two energy storage circuits connected in parallel each circuit comprising a second capacitor connected in parallel with second silicon controlled rectifier the second capacitors being charged through a blocking diode when a second D.C. power source is positioned conductive between the second capacitors and a second switch means, said second silicon controlled rectifier receiving induced potential from the secondary coil of a transformer as a result of discharge of firing capacitor through the primary coil of the transformer of a corresponding firing circuit when the first silicon controlled rectifier is in its conducting state, c. at least two blasting circuits connected in parallel each blasting circuit comprising output terminals connected to blasting initiator means within the blasting circuit, said output terminals receiving the output from the second capacitor of a corresponding energy storage circuit when the second silicon controlled rectifier is in the conducting state, and d. at least two timing circuits connectEd in parallel, each timing circuit comprising resistance means, a capacitor, and a unijunction transistor, a pulse from each unijunction transistor passing to the silicon controlled rectifier in a corresponding firing circuit initiating discharge of a second capacitor of an energy storage circuit into a blasting circuit when a third D.C. power source is positioned conductive between the timing circuits and a third switch means, the resistance-capacitance time constant for each successive timing circuit increasing in an amount necessary to delay discharge of the capacitors in the energy storage circuits into successive blasting circuits in the machine whereby current passes into the blasting circuits for initiating the blasting initiator means connected thereto at precisely controlled time intervals.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-29 | 1976-02-28 | 1976-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-29 | 1980-02-28 | 1980-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-29 | 1984-02-28 | 1984-08-29 | $7700.00 | Window Closed / Lapsed |