Technical developments in stemming of blast holes have long lagged behind other advancements in the blasting industry, which has focused on explosives, detonators, blast design modelling, more precise drilling and sequencing control.
Generally, blast holes are stemmed with rock aggregate, drill cuttings or crusher-processed materials to try to contain the explosive energy. There has been limited research or attempts to increase blast performance by using more advanced stemming materials. The focus on blast containment has done little to capitalize on the benefits of using the blast pressure wave energy for gains in rock fracturing and fragmentation. Effective control of the pressure wave energy can enhance attenuation, reflection and cause constructive interference that will increase the shear and stress energy transfer throughout the rock formation. Consistent and effective control of the blast pressure wave cannot be achieved with traditional aggregate and the variables experienced when loading the hole.
Shockwave Gel Technologies
Shockwave GT is a specialist chemical group with innovative stemming technology using a Hydrogel for use in all mining operations to improve mine safety and blasting performance.
STEMGEL TM is a patented stemming hydrogel with a constant, predictable attenuation and reflection of the pressure wave. The innovation enables the reflection of the energy pressure waves back into the rock formation to enhance rock fragmentation and explosive energy. Shockwaves reinforce and amplify one another to produce increased fragmentation, reflected stress waves are of prime importance to rock breakage. Rock aggregate stemming has no effect on control of pressure wave energy. The innovation brings a significant change to stemming resulting in lower dust and noise emissions and a tool to manage water in the hole.
The group has teamed with industry suppliers Stemsafe and IMA International mining accessories a subsidiary sister company to engineering form Stemtite. Together the groups have engineered Gel drives dose systems to place the STEMGEL in the blast hole with fewer truck movements on the blast bench that aggregate trucks. The fast-setting Stemgel will hold in vertical blast holes enable stemming to be effective in underground blast environments where little or no stemming options are suitable.
The efficiency of using a hydrogel stem material will enable users to decrease the stem deck horizon, minimizing oversize risk, and stab hole blasts. Gel drives work in a similar process to emulsion, hose in hose the Stemgel concentrate is mixed with water at the tail to set coupled with the explosive and hole walls. Stemming can be pumped up to 50 meters reducing the risk on contour blats where the terrain makes it dangerous to manage and load holes with aggregate.
Attenuation and reflection of the pressure wave in advance of the gas breaks the rock providing spaces for the gas to move and increase heave resulting in lower over pressure, vibration and noise. Contractors are trained and only licensed users can provide Stemgel products and services ensuring quality and control as miners develop their own value chain for the innovation technology. Its unique properties enable control for hot and reactive ground issues.
Industry innovation
There has been little progress to stemming innovation whilst significant changes in explosives, electronic dentation, data collection and blast design. Shockwave application of STEMGEL is a low-cost solution to age old problem, and moves from corking or capping a blast to retain the gas blast energy with a mass, to using the Pressure wave reflection based on the physics reaction a pressure wave has when it attempts to pass through a Hydrogel stabilised water stem deck. It provides a high degree constant control in stemming that aggregate cannot, and opens up the stemming tool to strata decking and a new level of blast energy control, and efficiency.
Mason Trouchet Shockwave Executive Director says its been an obvious market opportunity to innovate the stemming options from aggregate, the challenge has been to develop the Gel drive dose systems so we can execute the delivery of the product into the hole. Data collection is ongoing and whilst Shockwave focus on the interaction between the blast energy and the Stemgel interphase clients focus is on the consequences of the pressure wave reflections and blast movement of the rock and fragmentation. The Stemgel provides a tool to stem control with open-ended ideas for each mining circumstances.