Research and prospect of non-explosive continuous mining mode of underground hard rock mine based on supercritical CO₂ jet rock breaking

Non-explosive rock continuous mining is an important means and approach to achieve safe, green, and efficient underground hard rock mining in the future. This paper summarizes the current research status of non-explosive rock continuous mining, and mainly focuses on mechanical rock breaking and liquid CO₂ blasting rock breaking for underground hard rock mines. Unlike liquid CO₂ blasting for rock breaking, this paper proposes a non-explosive continuous mining mode based on supercritical CO₂ jet rock breaking. Utilizing the excellent fluidity and permeability of supercritical CO₂, under ultra-high pressure conditions, it directly fractures and destroys the rock layer when it is incident on it. Then, the gasification volume of supercritical CO₂ rapidly expands, further expanding the fracturing effect of the rock layer. In theory, this rock breaking method is safe, controllable, environmentally friendly, and has not yet been applied in the field of mining. It has high innovation, but it requires high development of supercritical jet equipment. Based on this research, a supercritical CO₂ jet rock breaking equipment and a drill bit equipped with nozzles are designed. Three continuous mining process modes for supercritical CO₂ jet hard rock breaking under different mining conditions are proposed, and future problems that urgently need to be studied and solved are identified and discussed.