To provide effective stabilisation against geological disturbances, CHRYSO® TSL liquid polymer (LP) dustless, thin-skin liner has been applied over 1 400 m2 of highwall at the Tweefontein coal mine central pit near Ogies in Mpumalanga.
View of the highwall prior to work commencing.
The main contractor on the job was the highly experienced Witbank-based mining roof support contractor Martiq, whose owner, Japie Kleinhans, has spent over 20 years in this sector. The choice of CHRYSO® TSL LP, which is a two-part product, was to ensure durability by blocking off the rock strata from weathering and oxidation.
The two-part CHRYSO TSL system was specially modified and adapted by new business manager, Frans Bakselerowicz, and chief chemist, Warren Delaney, for the coal mines. Hours of testing and changing mix designs improved the adhesion, biaxial flexural and tensile strengths. The two part and single part TSL are available in natural grey and a brilliant white.
In this application, the access from the top of the 23 m highwall made the process easier, as the contractor needed to reach the top of the wall area and 5 m over the edge. The gravity feed of the 30 m pipe also facilitated the successful spraying process. Five portal entrances giving access into the mine were also treated with CHRYSO® TSL LP to stabilise the coal substrate.
The top of the highwall cleaned, meshed and sealed.
With its extensive expertise in concrete, cement and additives, CHRYSO Southern Africa was able to assist the contractor with consulting services on the project, which was successfully completed in June 2018.
The CHRYSO® TSL LP two-part package comprises fillers, cement and additives, and polymer. The dry powders are premixed to make the mixing process more convenient.
Sprayed onto the required surface at a thickness of between 5 mm and 10 mm, the product’s excellent flowability ensures deeper penetration into crevasses and cracks in the laminated sandstone and shale substrate. It also offers a cost saving and less rebound, as well as quicker application when compared to gunite or shotcrete equivalents. The application is less labour‑intensive, and is easy to mix.
CHRYSO® TSL LP offers significant health and safety benefits to those working in the environment of the mine or tunnel as it is dustless, non-flammable and non-toxic. Its fast setting quality gives it early strength gains, whiles its high flexural strength properties provide a flexible barrier. The lining also displays good tensile strength when applied to a large portion of the substrate.
In addition to providing soil stabilisation of tunnel works and a reinforcement protection barrier against rock strain movements, CHRYSO® TSL LP can be used as a permanent surface. It can also be used to stabilise areas that are prone to soil movements, as a protection barrier against weathering and soil erosion, and as a liner to prevent rock from oxidising.