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Underground Stemming Plugs

102mm Pineapples in production

See our Pineapple stemming plugs being made in Sydney, Australia.  Video courtesy of Tom Mastrioni at Mastroplas Injection Moulding in Sydney. 

89mm and 64mm Prototypes now available

89mm and 64mm Pineapple stemming plugs are now being sent out to partner mines for trials.  In particular, these plugs include some learnings from the 102mm Pineapple that will make these plugs slightly easier to handle and install in the hole.  Get in touch if you want to try some or are interested in the production version due towards the end of the year. 


Development stemming prototypes available now.

We now have available a number of development stemming (46mm) Pineapple prototypes for testing as a result of industry request.  Get in touch if you want to be involved in trials. 


See our News section for updates. 


102mm Pineapple stemming plugs are here !

Our first batch of production Pineapple stemming plugs are here.  See our News section for details, or Contact Us for more information including availability and pricing.  

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Installation is easy

To install the plug, clip the detonator leads into place, connect on to the charge hose and push the plug into position.  Then retract the charge hose.


How easy is that ? 

Installation perspective.gif

Retraction in case of misfire

With safety in mind, the Pineapple stemming plug can easily be retracted in the event of a misfire.  Connect the grapple provided tot he end of the charge hose, push the hose up to the plug location and retrieve the hose and the plug. 

We do recommend double priming as you normally would to reduce the chance of misfires.  Of course in broken ground it may not be possible to retrieve the plug. 

retraction perspective.gif

Why stem upholes ?

Traditionally stemming has not been available for upholes, so typically mines don't stem.  What's the problem then ?  Severe damage to brows and to ground support in the immediate vicinity of firing, particularly with slashing shots or using the western method (firing an orebody from the footwall drive).  This can now be prevented.  The cost of sending a jumbo back in to rehab a drive is huge.  So if the damage is preventable, it makes sense to use stemming. 

For those mines cutting pillars, eg for undercuts in a block cave, grouting has been the only realistic option...  until now. 

This is a new stemming concept for underground mining and it has the potential to change the way we blast underground. Please get in touch to let us know what your needs are and what your price expectations will be.  The more volume we can get for each size, the lower our manufacturing costs and therefore pricing. 


Provides Drill and Blast Engineers with a new tool

  • Easily installed

  • Can be installed at any location in the collar (ie even 35m up)

  • Allows for two detonator leads for double priming

  • Does not need tamping in upholes

  • Will provide greater kick to your charge

  • Will prevent damage from rifling and blowing out the collar

  • Can be removed in case of a misfire

  • Allows for better brow control in longhole shots

  • Can be used to reduce powder factor and / or increase fragmentation

About Us

Jeff Phillips

Mining Engineer,Business Owner and Inventor.

B.Eng (Mining),B.Econs,B.Commerce (Finance), M.AusIMM

Jeff Phillips has 25 years mining industry experience,and holds a West Australian First Class Mine Manager's Certificate of Competency.  


In 2010 Jeff founded DD Grout Plugs, which designs and supplies unique pressure and load rated diamond drill hole plugs globally to underground mining operations.  


The Underground Stemming products were designed as simple, effective and easy to use products to give greater control over underground blasting operations. 


Jeff holds a number of patents and patent applications on the designs.

Jeff is a member of the Australian Institute of Mining and Metallurgy (AusIMM).

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