# US 2013/0152812 A1 · High energy blasting > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0152812 A1 - Document ID: US20130152812A1 - Status: Published application - Kind: A1 - Application number: 13/641,222 - Filed: 2011-04-15 - Published: 2013-06-20 - Earliest claimed: 2010-04-15 - Assignees: Orica International Pte Ltd - Inventors: Geoffrey Frederick Brent; Tapan Goswami; Michael John Noy; Peter Dare-Bryan - Web page: https://patentgrep.com/patent/US20130152812A1 ## CPC - F42D 3/04: for rock blasting - F42D 1/055: specially adapted for firing multiple charges with a time delay - F42D 1/08: Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor - F42D: BLASTING (fuses, e.g. fuse cords, C06C5/00; {for obtaining fluid from wells E21B43/00; for mining or quarrying E21C37/00; for making tunnels or galleries E21D9/006}; cartridges F42B3/00) ## Abstract A method of blasting rock, in mining for recoverable material, comprising drilling blastholes in a blast zone loading the blastholes with explosives and then firing the explosives in the blastholes in a single cycle of drilling, loading and blasting. The blast zone comprises a high energy blast zone in which blastholes are partially loaded with a first explosive to provide a high energy layer of the high energy blast zone having a powder factor of at least 1.75 kg of explosive per cubic metre of unblasted rock in the high energy layer and in which at least some of those blastholes are also loaded with a second explosive to provide a low energy layer of the high energy blast zone between the high energy layer and the adjacent end of those blastholes, said low energy layer having a powder factor that is at least a factor of two lower than the powder factor of said high energy layer. The high energy blasting method provides improved rock fragmentation through increased explosive energy concentration while simultaneously alleviating deleterious environment blast effects. ## Claims ### Claim 1 In mining for recoverable mineral, a method of blasting rock comprising drilling blastholes in a blast zone, loading the blastholes with explosives and then firing the explosives in the blastholes in a single cycle of drilling, loading and blasting, wherein the blast zone comprises a high energy blast zone in which blastholes are partially loaded with a first explosive to provide a high energy layer of the high energy blast zone having a powder factor of at least 1.75 kg of explosive per cubic metre of unblasted rock in the high energy layer and in which at least some of those blastholes are also loaded with a second explosive to provide a low energy layer of the high energy blast zone between the high energy layer and the adjacent end of those blastholes, said low energy layer having a powder factor that is at least a factor of two lower than the powder factor of said high energy layer. ### Claim 2 (depends on 1) A method according to claim 1, wherein the low energy layer has a powder factor of at most 2.0 kg of second explosive per cubic metre of unblasted rock in the low energy layer. ### Claim 3 (depends on 1) A method according to claim 1, wherein the low energy layer has a powder factor of at most 1.5 kg of second explosive per cubic metre of unblasted rock in the low energy layer. ### Claim 4 (depends on 1) A method according to claim 1, wherein the low energy layer has a depth or thickness, in the direction perpendicularly away from the high energy layer, of at least 2 m. ### Claim 5 (depends on 1) A method according to claim 1, wherein the high energy layer has a powder factor of at least 2 kg of first explosive per cubic metre of unblasted rock in the high energy layer. ### Claim 6 (depends on 1) A method according to claim 1, wherein the high energy layer has a powder factor of at least 2.5 kg of first explosive per cubic metre of unblasted rock in the high energy layer. ### Claim 7 (depends on 1) A method according to claim 1, wherein the high energy layer has a powder factor of up to 20 kg of first explosive per cubic metre of unblasted rock in the high energy layer. ### Claim 8 (depends on 1) A method according to claim 1, wherein at least those blastholes in the high energy zone loaded with both first explosive and second explosive have a first diameter portion loaded with the first explosive and a second diameter portion loaded with the second explosive, and wherein the first diameter is greater than the second diameter. ### Claim 9 (depends on 1) A method according to claim 1, wherein the first explosive has a greater density than the second explosive. ### Claim 10 (depends on 1) A method according to claim 1, wherein the first explosive has a greater blast energy per unit mass than the second explosive. ### Claim 11 (depends on 1) A method according to claim 1, wherein the first explosive has a greater blast velocity of detonation than the second explosive. ### Claim 12 (depends on 1) A method according to claim 1, wherein the first explosive is the same as the second explosive. ### Claim 13 (depends on 1) A method according to claim 1, wherein at least some of those blastholes in the high energy zone loaded with both first explosive and second explosive have at least one inert deck of stemming or air in the low energy layer. ### Claim 14 (depends on 1) A method according to claim 1, wherein there are blastholes in the high energy zone loaded with first explosive but not with second explosive, and wherein those blastholes have at least one inert deck of stemming or air in the low energy layer between the high energy layer and the adjacent end of those blastholes. ### Claim 15 (depends on 1) A method according to claim 1, wherein the step of blasting in the high energy zone comprises firing the explosives in the high and low energy layers sequentially. ### Claim 16 (depends on 15) A method according to claim 15, wherein the first explosive in the high energy layer is fired after the second explosive in the low energy layer. ### Claim 17 (depends on 15) A method according to claim 15, wherein the blasting of the second explosive in the low energy layer results in a blanket of blasted material over the high energy layer. ### Claim 18 (depends on 15) A method according to claim 15, wherein any charge of the explosive to be fired in one of the high and low energy layers is fired at least about 500 ms after firing the nearest charge of the explosive in the other of the high and low energy layers. ### Claim 19 (depends on 18) A method according to claim 18, wherein a first charge of the explosive to be fired in said one of the high and low energy layers is fired at least about 500 ms after firing the last charge of the explosive in said other of the high and low energy layers. ### Claim 20 (depends on 1) A method according to claim 1, wherein the blasting is in an open cut mine in which the blastholes extend downwardly and the high energy layer is beneath the low energy layer. ### Claim 21 (depends on 20) A method according to claim 20, wherein the first explosive in the high energy layer is offset from a toe of the blastholes or from the design blast floor level in the high energy blast zone. ### Claim 22 (depends on 21) A method according to claim 21, wherein at least some of the blastholes in the high energy blast zone loaded with first explosive are also loaded with further explosive to provide a second low energy layer between the high energy layer and the toes of the blastholes in the high energy blast zone, said second low energy layer having a powder factor that is at least a factor of two lower than the powder factor of the high energy layer. ### Claim 23 (depends on 22) A method according to claim 22, wherein the second low energy layer has a powder factor of at most 1.5 kg of explosive per cubic metre of unblasted rock in the second low energy layer. ### Claim 24 (depends on 1) A method according to claim 1, wherein the blasting is in an underground mine and the first explosive and the second explosive are loaded, respectively, closer to a collar of the blastholes and closer to a toe of the blastholes. ### Claim 25 (depends on 24) A method according to claim 24, wherein the first explosive in the high energy layer is offset from a collar of the blastholes in the high energy blast zone. ### Claim 26 (depends on 25) A method according to claim 25, wherein at least some of the blastholes in the high energy blast zone loaded with first explosive are also loaded with further explosive to provide a second low energy layer between the high energy layer and the collars of the blastholes in the high energy blast zone, said second low energy layer having a powder factor that is at least a factor two lower than the powder factor of the high energy layer. ### Claim 27 (depends on 26) A method according to claim 26, wherein the second low energy layer has a powder factor of at most 1.5 kg of explosive per cubic metre of unblasted rock in the second low energy layer. ### Claim 28 (depends on 1) A method according to claim 1, wherein the blast zone has a perimeter, and the high energy blast zone is isolated from the perimeter by a low energy blast zone comprising blastholes that are drilled, loaded and blasted in said single cycle, said blastholes in the low energy blast zone being loaded with explosive to provide a powder factor that is at least a factor of two lower than the powder factor of the high energy layer of the high energy blast zone. ### Claim 29 (depends on 28) A method according to claim 28, wherein the low energy blast zone has a powder factor of at most 1.5 kg of explosive per cubic metre of unblasted rock in the low energy blast zone. ### Claim 30 (depends on 28) A method according to claim 28, wherein the low energy blast zone extends entirely around the high energy blast zone. ### Claim 31 (depends on 28) A method according to claim 28, wherein the explosives in the high energy blast zone are fired after at least the nearest explosive in the low energy blast zone has been fired. ### Claim 32 (depends on 31) A method according to claim 31, wherein the explosives in the high energy blast zone are fired at least about 500 ms after at least the nearest explosive in the low energy blast zone has been fired. ### Claim 33 (depends on 31) A method according to claim 31, wherein the explosives in the high energy blast zone are fired after all of the explosive in the low energy blast zone has been fired. ### Claim 34 (depends on 33) A method according to claim 33, wherein the explosives in the high energy blast zone are fired at least about 500 ms after all of the explosive in the low energy blast zone has been fired. ### Claim 35 (depends on 1) A method according to claim 1, wherein the recoverable mineral is metalliferous. ### Claim 36 (depends on 1) A method according to claim 1, wherein the explosives are initiated using electronic delay detonators. ### Claim 37 (depends on 1) A method according to claim 1, wherein the first and second explosives in any one blasthole are fired at the same time. ### Claim 38 (depends on 37) A method according to claim 37, wherein columns of the first and second explosives in said any one blasthole are contiguous. ### Claim 39 (depends on 17) A method according to claim 17, wherein the method results in the rock blasted in the high energy blast zone remaining within the high energy blast zone.