Mining solutions firm Gazmick worked with the Additive Manufacturing Hub in the development of an innovative new concept for rock bolts used to provide mining ground support.

Gazmick is a small, privately owned business dedicated to improving ground support in the mining industry. Gazmick has enjoyed great success in patenting novel ground support solutions, such as rock bolts. Up to now its most successful bolt is the Stiff Split Set, a modified friction bolt. Via a licensing agreement, Gazmick has sold in excess of 4 million units throughout Australia and Asia. Gazmick looks to solve other rock bolt problems to enhance the safety and efficiency of mining and tunnelling operations.

The challenge

One common type of rock bolt is the resin bolt. In this embodiment a steel bar is locked into the rock using a two-part resin pack. Currently the resin is contained in a two-part “sausage” and placed into the hole in the strata. To avoid danger this is done remotely, with the operator working approximately five metres away behind a protective steel canopy. This resin installation process has remained unchanged for the last ten years and contributes significantly to the entire bolting cycle time. The process is:

  1. Drill the hole.
  2. Insert multiple sausages.
  3. Insert the steel bar rotating it and thereby mixing the resin at the same time.

A method of more easily placing resin and rock bolts in holes has been sought for a considerable period of time with little success.

Gazmick developed a patented solution whereby a canister full of resin, similar to a hypodermic syringe, is placed onto the rock bolt. The resin and hardener are separated in the canister. The nozzle of the canister is placed into a hole and the combination of the two products are injected into the hole by applying force to the rock bolt. Once the material is fully injected into the hole, further force is placed onto the steel bar. This punctures the top of the canister and allows the rock bolt to enter the hole through the nozzle of the canister. The bolt spins, thereby mixing the product, and a plate attached to the rock bolt crushes the canister between the strata and the plate.

Using this method, the old three-step process is reduced to two. It offers mine operators greater safety, improved quality of installation, and invaluable time-savings. The speed of the process is worth millions of dollars to mining companies worldwide.

The difficulty Gazmick faced was in determining and proving the mechanical properties of the canister. The tolerances are relatively small, and the need for accurate implementation activation was critical. Moreover, if the crown of the “piston” inside the canister was too strong the bolt could not pierce it and enter the hole. If it was too weak, the bolt would break through prematurely and the resin would not be injected into the hole. Getting the balance of all the components was critical in determining the practicalities of the concept.

Injection moulding of protypes would be far too expensive so a fast-tracked, cheap prototype construction method was required so that destructive testing could be undertaken. An additive manufacturing program using 3D printing techniques was identified as the fastest and most cost-effective way to construct the protypes, at which point Gazmick sought assistance from the Additive Manufacturing Hub (AM Hub).

The solution

The AM Hub engaged registered service providers GoProto (ANZ) Pty Ltd to assist Gazmick in its project. A finite element analysis (FEA) was undertaken of critical parts of the device. The physical properties of the crown of the piston inside the canister were critical. Prototypes were then 3D printed and tested against break-out strength in a calibrated load device.

Once a “preferred protype” was achieved, these were tested at the property of a Gazmick partner, where the use of a rock bolt simulation rig test could be undertaken. After multiple iterations, a successful combination of size and strength was achieved, and near-perfect results of resin mixing and rockbolt installation were observed in test sample cross sections.

How the Additive Manufacturing Hub helped

It was predicated that the project would make full use of a $17,940 co-contribution under the AM Hub’s Build It Better (BiB) voucher programme for 3D printing performed by GoProto ANZ. In the end, a total of $3,032.22 in total was spent. The fast-tracking of prototypes exceeded expectations, despite some delays that occurred as a result of fires in southern New South Wales, where the test facility was located, and because of the COVID-19 pandemic, which stopped all testing-related travel.

Project outcomes

Gazmick was able to test multiple iterations of its concept, which provided enough confidence to move forward with specialised in-field test prototypes – these are about to be constructed. The demonstration of the concept has also provided the confidence for a multi-national company to sign a heads of agreement with Gazmick, which will allow further testing and an option to manufacture and supply this product for worldwide distribution.

There is still work to be done, but Gazmick confidence has been greatly enhanced and the team are looking forward to conducting mine site trials in the immediate future.

The AM Hub is an initiative delivered by AMTIL in partnership with the Victorian State Government to promote the adoption of additive manufacturing technology. For more information, please contact John Croft, AM Hub Manager, on 03 9800 3666 or email amhub@amtil.com.au.

www.amhub.net.au

www.goproto.com.au