Fracture of Firm Monoliths
Development of Mobile Impact Facility for Fracture of Oversize Firm Rocks, Concrete and Ferroconcrete Constructions with Use of Energy of Explosion Localized in Closed Chamber
Tech Area / Field
- OTH-BIT/Building Industry Technology/Other
8 Project completed
Senior Project Manager
Latynin K V
VNIIEF, Russia, N. Novgorod reg., Sarov
- University of Miami / Clean Energy Research Institute, USA, FL, Coral Gables
Project summaryGoal of Project: development of a powerful, mobile impact facility, which would be simple and safe for operation, for fracture of firm rocks and monolithic constructions.
The Project is intended for solving the problems of:
- destruction (fracture) of monolithic constructions in the building industry (concrete and ferroconcrete constructions, foundation, etc.),
- fracture of oversize firm rocks in mining and extraction industries, diamond industry. The term “oversize” means rock fragments produced during quarry by excavation with use of explosive efforts, where these fragments should be further fragmented for smaller sizes. And dimensions of these fragments are more than dimensions of grinding facilities.
Essence of Project:
Development and manufacture of an experimental sample – prototype of a mobile impact facility, which uses energy of explosion in closed volume (explosive generator of pressure) for initiating work of operational tool. The facility would be capable to fracture firm monolithic constructions.
The facility under development should comply with some certain requirements, namely, to provide
- localization of explosion products,
- safety of personnel near the facility during its operation,
- application of cheap industrial explosives,
- repeatability of operation and indestructibility of basic operational elements,
- capability of fast recharging (high rate of operation),
- capability of independent operation, as well as operation on moving vehicles, for example, on a truck crane, a bulldozer, etc.
- capability to work in vertical and horizontal positions.
Practical value of Project:
Destruction (fracture) of oversize rocks or concrete constructions (foundations, etc.) is traditionally performed either by overlay charges of high explosive (HE), or by HE charges placed in boreholes drilled in objects to be destroyed. In these cases, after explosion, toxic substances are released as explosion products, fragments, and great quantity of dust caused by fractured material.
Basic disadvantages of the traditional methods:
A) During efforts in open-cast mine for stone excavation:
- Need for stop of all technological cycle in open-cast mine for conduction of detonation (fracture) of oversize slabs. All the other efforts in the open-cast mine should be stopped for this time, personnel and equipment should be shielded in safe place.
- Additional expenses for drilling boreholes (in case of borehole charges).
- Significant consumption of HE when fracturing by overlay charges, and formation of a rather powerful shock wave.
B) During explosive destruction of concrete (ferroconcrete) construction:
- Expenses for drilling boreholes,
- Need to shelter personnel and equipment,
- Formation of large quantity of toxic explosion products and large quantity of fractions as dust from fractured material.
Dust formation is especially critical when demounting concrete constructions of worked-out nuclear power plants (NPP), since induced radioactivity in cement dust is greatly hazardous both for personnel and population of the region, where this NPP is demounted.
Project participants suggest their new promising development of an impact-type reusable explosive facility. Comparing to the traditional methods, this facility provides destruction of monolithic constructions with use of less HE charges. Besides, it reduces release of explosion products into atmosphere due to localization of them, and it reduces formation of dust fractions from destroyed material because of absence of direct brisant effect of high explosive on the object under destruction. No any manifestations of shock waves are observed during operation of the facility.
For acceleration of the operational (cracking) tool, the proposed development uses energy of explosion products of brisant explosive detonated in closed volume – an explosive generator of pressure (EGP).
Explosive generators of pressure, which are developed in FSUE RFNC-VNIIEF, can be considered as reusable devices. Experience of EGP application in the other facilities reveals that they keep their intactness and functioning capabilities for long time after many cycles of operation. For their operation, it is possible to use any industrial explosives applied in the rock industry. Though having HE charge, EGPs within the functional devices of various intentions can be regarded as “explosion-proof” devices. I.e. even at non-authorized detonation of HE in them, engineering measures exclude release of explosion products into atmosphere as flame, debris and shock wave that can injure the personnel.
Schematically, the facility is a metal cylinder, inside of which a charge of high explosive is detonated. Explosion products accelerate a massive impactor – “cleaver”. This “cleaver” is driven forward from the cylinder with high velocity for some distance, then it imparts pulse of high intensity to the object under destruction and fractures this object. After that, the impacting system is cocked, a new charge is placed, and the facility is again ready for operation.
The facility, which is proposed for development, has a series of advantages:
- Customer gets rid of need for outage of regular efforts in open-cast mine when fracturing oversize slabs by this facility, since there are no hazardous factors, which are peculiar to “open explosion” with resulted consequences;
- Since destruction of a construction is performed by powerful impact of the operational tool against construction surface, where the operational tool is driven by explosion products localized in closed volume, formation of dust fractions is reduced to minimum during material fracture.
- The facility has high specific energy output (power/weight) at small cost of energy source (it is expected to use small charges of standard compositions of ammonite-type explosives, which are commonly used in the rock and mineral resource industry);
- The facility has short-time payback at small cost of it.
The proposed development is promising and can be used both being at the stage of verification of various variants of its design and as the final variant for dismantling ferroconcrete constructions of nuclear power plants, for example, at Ingalinskaya NPP in Lithuania (which should be closed according to European Economic Community requirements). Here release of toxic explosion products into atmosphere and formation of radioactive dust fractions from a destroyed object is reduced to minimum.
The other potential consumers are companies from the mining industry, and companies which are involved in quarrying of building stone (crushed stone) in granite, basalt, dolomite and other open-cast mines.
The authorities of company «Diamonds of Russia» expressed interest in this facility for use of it for fragmentation of stone slabs containing diamonds. Since, fragmentation of a stone slab by the proposed facility occurs without formation of detonation shock wave, which is typical for the traditional explosive method, and which destroys both the stone slab and diamonds inside of it. After appropriate advertising of the project results, interest from the other diamond-quarrying companies is possible.
The pilot facility prototype is planned to be manufactured at the machine-building plant “Zhemchug” in the city of Voznesensk (Nizhny Novgorod Region) under a specific subcontract.
The project efforts will involve large experience of FSUE RFNC-VNIIEF in study of behavior of various materials under dynamic loading and large experience of FSUE RFNC-VNIIEF in development of impact-type reusable explosive facilities intended for providing dynamic loading of various levels.
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