I can recommend two books:
SMALL MINES OF SOUTH WALES [= Vol 1] by A J Booth 1995 96 pp over 120 photos, 32 maps. A superb book of black and white photos of some of the privately owned mines in South Wales interspersed with many anecdotes. For each of the 32 mines there is NGR, description type of coal, method of haulage etc. A timely historical record. SB
SMALL MINES OF SOUTH WALES Vol 2 by A J Booth 1997 112 pp 145 photos, 32 maps. A superb book of black and white photos of some of the privately owned mines in South Wales interspersed with many anecdotes. For each of the 34 mines there is NGR, description type of coal, method of haulage etc. A timely historical record.
Cutting coal in my spare time.