No abstract

Corrosion of rock bolts is a relatively slow process yet a potential problem for the underground mining industry. Mine groundwater in the strata through natural or mining-induced cracks together with the humid environment in the mine openings interact with the roof support systems often resulting in corrosion. Electrochemical studies of the commonly used rock bolt steel in the coal mining environments will lead to a better understanding of the material's performance and their ability to resist corrosion. The influence of pH, solution resistivity, total dissolved solids, and aggressive ions on the electrochemical properties of rock bolt steel are discussed. This preliminary study focuses on understanding the corrosion potential, polarization resistance, and corrosion rates of the rock bolt steel that is most commonly used in US underground coal mines. Based on the findings, it was observed that the polarization resistance (Rp) is inversely proportional to the corrosion rate (CR) over time.

Corrosion of roof bolts in underground mine environments could have an adverse impact on ground control, which is directly related to workforce safety. Past studies state that stress corrosion cracking (SCC) of roof bolts is a significant problem in underground coal mines, resulting in premature bolt failures. However, it has not been seriously studied in U.S. underground coal mines. As a preliminary study, the most common roof bolt material used in U.S. mines, ASTM A 615 Grade 60 steel, was studied under stress corrosion conditions. ASTM G30 standard was applied to achieve this and tested in the simulated coal mine conditions. SCC was observed on samples that were tested for 180 days. Chloride SCC (ClSCC) was found to be the corrosion mechanism resulting in cracks from the EDS data. This paper mainly discusses the test protocol, shortcomings of this preliminary testing and makes recommendations based on the observations and results.