C F I
Controlled
Foam
Injection
CFI Technologies, Inc. has acquired the patents and rights to
the Controlled Foam Injection method of rock excavation.
CFI-Tech will continue the development and application of this revolutionary non-explosive method for hard rock excavation, secondary breakage and concrete demolition.
The method utilizes the proprietary and patent protected Controlled Foam Injection (CFI) technique to fracture rock and concrete. The use of high-pressure foam as the fracturing and medium completely eliminates the air-blast, fly-rock and toxic fume problems associated with explosive based techniques. The CFI method may be used in very close proximity to personnel, sensitive structures or equipment. The controlled breakage characteristic of the CFI method allows for rock removal to very precise dimensions with minimal damage to the remaining rock. All the process byproducts are environmentally benign and completely biodegradable.
Principles of the CFI method
The CFI method is based upon the use of high-pressure foam to initiate, pressurize and propagate controlled fracturing in rock and concrete.
An injection barrel, incorporating a proprietary hole-bottom seal, is used to rapidly inject high-pressure foam into the bottom of a pre-drilled hole
in the rock or concrete to be broken, as indicated in the animation at right.
The high viscosity of the foam (as compared to a gas) combined with its stored energy characteristics (as compared to a liquid) result in very
controlled and efficient breakage.
The foam pressures required to break rock or concrete are significantly less than required in explosive or propellant based methods.
Consequently, air-blast and fly-rock are reduced to very benign levels, allowing the method to be applied in a continuous manner and
to be used in urban and other sensitive environments.
Two CFI systems are shown mounted on representative carriers at the top of this page. The machine at the upper left is a small 4,500 kg (5 ton) tracked carrier with a radio remote control system. The unit at upper right shows a CFI system mounted on a Volvo EW55 wheeled excavator weighing 5,500 kg (6 ton) and which can be operated from the protected cab. These machines have been tested and demonstrated on small projects and are now available for dedicated commercial projects.
The foam is made with a water based liquid and high-pressure air, in proportions based upon the rock or concrete breakage conditions. As the foam comprises water and non-toxic, biodegradable, gels and surfactants the foam is biodegradable and environmentally friendly. It may be used without risk to personnel and does not require any concern for disposal.
Applications of CFI breakage
The CFI method is well suited for automation. The flexibility of the method (in terms of hole depth and foam pressure, quality and viscosity) allows it to be tailored to rapidly changing ground conditions or a variety of breakage conditions. The benign nature of the air-blast and fly-rock of the CFI fracturing method allows drilling, breakage, mucking, ground support and haulage equipment to remain at the working point or face during rock excavation operations. Operating personnel may control operations by radio-remote from nearby, line-of-sight, locations or from a protected cab providing direct observation of operations.
The proprietary foam-based CFI method can be used in a broad variety of rock breaking and excavation situations. The method is ideally suited for the demolition of oversized boulders encountered in both construction and mining operations. The CFI method can be used to develop trenches for utility or pipe lines or caisson shafts for bridges and power line towers. The method can be used to excavate utility tunnels under existing streets and buildings, to provide access tunnels or shafts to existing subway systems, or to create or enlarge underground space for buildings. In underground mining operations, the CFI method can be used for selective mining or for mine development in unstable ground. As the method imparts negligible damage to the remaining rock, the need for ground support can be significantly reduced. The CFI method is ideally suited for any excavation or breakage situation where conventional explosive methods are precluded, whether for environmental, legal or public concern reasons.
A recently developed application of CFI rock fracturing is to utilize CFI fracturing to induce extensive fracturing into massive rock such that the fractures will improve the speed and efficiency of conventional techniques, such as rippers and impact breakers. For this application, the holes are usually drilled deeper and more distally spaced than for direct CFI excavation. Also the foam pressures and volumes are usually less. Consequently, there is no fly-rock and no risk to nearby personnel or machinery. A CFI system for such a complementary, or synergistic, application would usually be mounted on a wheeled excavator (such as the Volvo EW55 shown above) so as to provide rapid mobility. While surface excavation is the most predominant application, CFI rock-conditioning can be used to enhance face advance in mines and tunnels in combination with a road-header or similar rock breaking system.
For additional details on the development and commercialization of the CFI method,
please go to our known visitors page for details, news, video clips, publications and reference information.
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