Paste backfill and surface disposal pipelines occasionally plug due to plant control problems, sudden release of build-up on the inside of pipe walls, introduction of foreign material, spalling of unlined boreholes, power outages or equipment failure. Under a plugged condition it is necessary to open the pipeline and clean the cemented or uncemented paste out of the line prior to the entire line solidifying (either by curing of cemented paste or consolidation of uncemented paste). In the case of cemented paste the time available to clean out the line prior to it solidifying in the line can be less than two hours. To further complicate matters, the paste line can be under very high pressures and opening a pipeline should only be done once it has been depressurized. Because depressurization valves can be plugged by cemented or solidified paste opening a valve may not result in the line depressurizing and many mines use explosives to blast the cap off of a sacrificial flush tee in the pipeline to allow the line to be depressurized remotely and without placing operators at risk. Blasting of paste lines is a fairly common practice when dealing with plugs, however it is not an ideal due to the time to set up the charges, clear the area, obtain approvals etc. for the blast and in many cases, operators are not able to blast the line and clean it out prior to the paste curing in place. This paper presents a novel depressurization device that allows operators to open the pipeline and depressurize it remotely and safely without problems due to plugged tee branches or the expensive option of purchasing a purpose built depressurization valve. The depressurization device is inexpensive, easy for operators to install and maintain and requires no special skills to use. This device should replace the requirement for operators to blast pipelines during plugged conditions and provide a more convenient, safe and reliable method for cemented paste pipeline depressurizing.
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