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Accident analysis of mining industry in the United States - a retrospective study for 36 years

Rahimi Elham, Shekarian Younes, Shekarian Naser, Roghanchi Pedram

Journal of Sustainable Mining

2022

Vol. 21, iss. 1

27--44

A retrospective study on accident analysis of the United States mines for 36 years was achieved using statistical analysis on the MSHA's accident databases between 1983 and 2018. A regression model of generalized estimation equation (GEE) was used for unbalanced panel data that provided 95,812 observations for 19,924 mine-ID-year in aggregate, coal, metal, and non-metal mines. The contributions of various parameters, including mine type, injured body part, days lost, age, and experience on the rate of accidents and injuries were investigated across the commodity types. The results showed coal miners in the East region are at a higher risk of accident. The results of regression analysis show that mine-tenured workers have a vital role in accident frequencies. Analysis of the injured body part on the injury rate indicates that the upper body injuries are the most significant among all mine types. Also, the fatality rate is significant in aggregate, and coal mines in comparison with metal and non-metal mines.

Effect of coating steps on uniformity and gas permeability of mesoporous layers in ceramic membranes

Pakdehi Shahram G., Rahimi Elham, Shafiei Korosh

Materials Science Poland

2020

Vol. 38, No. 4

535--544

Porous silica, silica-cobalt, silica-zirconia and zirconia membranes were synthesized by the sol-gel method. Multi-step coating (two, six, and ten steps) was used to reduce the defectiveness of the mesoporous layer. Scanning electron microscopy (SEM) images indicated that an increase in the number of coating steps improved the mesoporous layer quality. The results obtained from gas permeability tests with nitrogen and argon, however, indicated a reduction in the gas permeability with increasing coating steps. The reduction in gas permeability from two to six coating steps was more pronounced than from six- to ten- coating steps. It was found that six-step coating was economically justified in obtaining a uniform mesoporous layer. The results of pore radius calculations by Knudsen flow mechanism revealed that the pores in the silica, silica-cobalt, and zirconia membranes were in the mesoporous range. The sols with a mean particle size more than 100 nm are not recommended for synthesis of mesoporous layer free of defects. Furthermore, the type of acid used as a catalyst is also important in obtaining a layer without defectiveness.