ROCK REINFORCEMENT
To improve bolting installation practices and installed rock reinforcement performance , and to meet the requirements of advanced mining company safety and efficiency expectation , the following systems were developed by Jennmar : n Mechanised bolting machine utilising a carousel of self-drilling anchors , J-Lok P polyester resin injection and nut tensioning through a boom indexing system n Mechanised bolting machine utilising a carousel of torque tension rebar / threadbar resin bolts , J-Wand polyester resin injection and nut tensioning through an indexing system n Fully integrated J-Lok P polyester resin injection on a Komatsu mechanised bolting machine n Platform bolter conversion n Twin-boom jumbo bolter with split-feed booms and J-Lok P polyester resin injection using various self-drilling anchor designs n Mechanised cable bolting machine utilising original equipment manufacturers ( OEM ) standard nylon grout tubes and J-Lok P polyester resin injection . The paper then detailed the development of a polyester resin injection for various rock and cable bolting applications , rock reinforcement design to support polyester resin injection , and comparisons of the performance of polyester and urea silicate resins in terms of material properties and application .
“ Polyester resins are the most widely used resin systems in different industries due to material availability , ease of use , low cost and excellent material properties . The operating service temperatures for polyester resins are wider than for other resin systems . Polyester resins are versatile because of their capacity to be modified or tailored during the manufacturing of the polymer chains . The principal advantage of polyester resins is a balance of properties ( including mechanical , chemical and electrical ), stability , lower cost and ease of handling or processing . For these reasons , Jennmar chose polyester resin for bolting injection applications .”
The authors add that the temperature effect on Part A and B of J-Lok P polyester resin appears to be relatively less significant . “ In cold weather , the resin and catalyst may be frozen . However , the low temperature will not affect the quality of the product and their functionalities remain the same once thawed . If ambient temperature is higher in summertime , viscosity of the J-Lok P Part A and B may drop slightly and sometimes filler particles may settle at the bottom of the intermediate bulk container ( IBC ). The quality of the resin and catalyst remains the same and minor solid-liquid separation is rectified by remixing resin in the IBC . If stored correctly , the shelf life of polyester J-Lok P resin in IBCs should exceed two years . However , it should only be used beyond the manufacturer ’ s recommended date after passing laboratory testing .”
The J-Lok P system is a specialised patented hydraulic , pneumatic or programmable logic controller- ( PLC- ) controlled pumping system . It comprises three main components : a highvolume resin transfer station , an on-board resin storage station and an injection module . Depending on the application and project requirements , system designs are modified to meet resin ratio , on-board resin storage volume , and carrier size and injection volume requirements . Polyester resin and catalyst transfer from bulk mobile handling systems to on-board resin is completed in approximately five minutes , assuming two 130-litre tanks are filled .
The cited advantages of employing the J-Lok P system , particularly in poor ground when using engineered solutions , are : n Improved quality control by reducing manual operator inputs . n An installed single-pass system designed to meet corrosion , dynamic and static requirements . n Designed ground support that economically mitigates risk with minimal future unplanned rehabilitation . n Products are designed using industry best practice and innovative methods . n A fit-for-purpose system that meets life of mine and design requirements . n Developed to be miner proof . n Utilises many current industry installation practices and machines to reduce unplanned disruption to the mining cycle . n Training , support and monitoring packages are tailored for operational requirements . Notably , Jennmar and Komatsu have collaborated to provide full OEM conversion kits and J-Lok P integrated polyester resin injection onto Komatsu mechanised bolting and Jumbo machines . The Komatsu ZB21 model is the smallest machine in the Komatsu fleet . Having the ability to miniaturise the J-Lok P system , and successfully mount and operate it while remaining within carrier design limits is a significant benefit for operations mining small development drives .
The Komatsu integration utilises a 2:1 ratio tank and injection system mounted inside the machine body . The design allows for easy access and function allows for simple maintenance as it is mounted on a hinged door .
The Komatsu ZB21 has many design benefits to support efficient bolting practices . These include utilising highly efficient Montabert drifters to improve penetration rates and drilling time . Single carrier used across bolter and Jumbo machines ; integrated control systems for all machine operations , including J-Lok P resin injection ; and patented screen-handling system . It also features a patented flexible bolt centraliser .
The J-Lok P system has been in service for many years now . The authors conclude : “ Continuous improvement , miniaturisation , adapting polyester resin injection across various markets and applications , and safety improvements have been beneficial to the mining industry , particularly mines in poor ground . The J- Lok P system now provides significant safety , quality control , efficiency and automation improvement for the mining , construction and tunnelling industries .”
Weber enhances performance of pumpable resin systems
Weber Mining and Tunnelling , with over 60 years of innovative product development , is one of the world ’ s most respected provider of resins and foams for ground consolidation , roof support , cavity filling , waterproofing , sealing and firefighting . The partnership between Weber Mining and underground mining equipment OEM Epiroc has resulted in the design and optimisation of the Potentia ® Thixo resin , a highperformance pumpable resin for use with Epiroc self-drilling , hollow core and pumpable rock bolts .
The two-component resin system is pumped and injected through a nozzle into hollow , selfdrilling , pumpable rock bolts . Upon mixing and injection , the resin starts to gel immediately , filling the annular space between the bolt and the drilled hole , thus forming a complete column bond . This streamlined , safe , and innovative application is highly effective due to the specially tailored thixotropic characteristics of the mixed components , which prevent leaks during grouting and ensure a robust column bond . This enhances load-bearing capacity and provides corrosion protection for the support tendons .
Through the integrated design and optimisation of both bolts and resin , Epiroc and Weber Mining have ensured optimal performance . The Potentia ® Thixo pumpable resin and Epiroc bolts work in synergy , whose entire application can be automated using the Epiroc Boltec . Weber told IM that the organomineral pumpable resins reach a compressive strength greater than 35 MPa . “ With a high bonding strength and a very low viscosity , they have a high capacity to bond and consolidate rock masses .”
When it comes to absorbing dynamic stresses and impacts , Potentia Thixo High Performance ( patented ), reaches a compressive strength
greater than 55 MPa has been designed to offer greater resistance to vibration and movements .
With adjustable reaction times and thixotropy , Potentia ® Thixo can be injected into bolts or cables of various lengths ( pre-grouting or post-
International Mining | AUGUST 2024