ST. LOUIS, July 27, 2021 /PRNewswire/ — Arch Resources, Inc. (NYSE: ARCH) today reported net income of $27.9 million, or $1.66 per diluted share, in the second quarter of 2021, compared with a net loss of $49.3 million, or $3.26 per diluted share, in the prior-year period. Arch had…