Effect of mixing water temperature on the mechanical performance of soundless chemical demolition agents for rock breakage

Rock fragmentation in hard rock mining has traditionally relied on explosives which raises significant environmental and safety concerns for both workers and local communities. In response, soundless chemical demolition agents (SCDAs) primarily composed of lime (CaO), offer safer and more sustainable alternative to traditional blasting due to their soundless, vibrationless, and fumeless properties. This study is focused on examining the effect of mixing water temperature on the rock breakage performance of two commercially available SCDA brands, namely Betonamit type R (BT-R) and Dexpan type 3 (DXP-3). The experiments were conducted using 15 cm cubic granite rock specimens as the host material under various ambient temperatures. The study revealed an increase in mixing water temperature significantly accelerates the mechanical performance of SCDAs, particularly in cold ambient conditions. For instance, increasing the mixing water temperature from 20°C to 40°C reduced the time to first crack (TFC) by 36 % for BT-R and 74 % for DXP-3 under an ambient temperature of 0°C. A corresponding reduction in minimum demolition time (MDT) was also observed. At higher ambient temperatures, the impact of mixing water temperature was found to be less pronounced for both SCDA types. It is concluded that high mixing water temperature would be highly recommended for cold climate applications in both open pit and underground mining.