coal mining crusher internal control questionnaire roller
coal mining internal control questionnaire. Coal mining in the United States is an industry in transition Production in 2017 was down 33% from the peak production of 1,1627 million short tons (1,055 million metric tons) in 2006Employment of 50,000 coal miners is down from a peak of 883,000 in 1923 Generation of electricity is the largest user of coal, being used to produce 50% of electric power in