Preparation and performance test of mixed EV-EP concrete thermal insulation coating

Heat and moisture transfer in the surrounding rock significantly contributes to the unfavorable thermal environment within wells. A prevalent technology for mitigating heat damage involves enhancing insulation properties by reducing heat transfer efficiency, thereby lowering temperatures in deep wells through the application of thermal insulation coatings. To explore this approach, orthogonal testing were conducted to evaluate how varying proportions of expanded vermiculite (EV), expanded perlite (EP), and ceramic fiber impact the performance of concrete thermal insulation coatings. Analysis of the test results revealed an optimal mixture ratio for a novel thermal insulation coating: it consists of 60 % fly ash, with a ceramsite -to-EP ratio set at 3:7, alongside 60 % EV and 10 % ceramic fiber. This formulation was subsequently applied in Linglong Gold Mine's tunnel, where engineering parameters were collected for numerical simulations. Roadway models were developed using FLUENT software to examine the effectiveness of thermal insulation under various operational conditions. The findings indicated that the resulting composite possesses remarkably low thermal conductivity, measuring only 0.0967 W/(m·K). Furthermore, an ideal insulating layer thickness was determined to be 0.25 m; this configuration has significant implications for improving thermal conductivity efficiency by as much as 65 % in roadways extending up to 1000 m. In conclusion, this new thermal insulation coating not only facilitates field construction and practical applications but also demonstrates exceptional thermal insulating properties. It holds promise as a highly valuable material for addressing heat management and cooling technologies in mining operations, thereby offering substantial benefits for resolving underground heat damage issues.