The earliest surface photos of Welsh metal mines that I can bring to mind are from the very early 1860s (various photos are reproduced in T.A.Morrison 'Goldmining in Western Merioneth', Llandysul, 1975 and in G.W.Hall 'The Gold Mines of Merioneth', Gloucester, 1975) and there are certainly surface views of Welsh Collieries of comparable date. Earlier photos of Merioneth gold mines are unlikely as it was only in the 1860s that they really began to command massive public attention and hence attract photographers.
Quite possibly Snowdon (Llanberis) Copper Mine, being adjacent to one of the mid C19 tourist paths up Snowdon, may be the first Welsh metal mine to feature in photographs.
C.Howes 'To Photograph Darkness: a history of underground and flash photography', Gloucester, 1989, establishes that the earliest known underground mine photographs were taken in Bradford Colliery, Bentley, near Doncaster, Yorkshire, in March 1865 (four exposures of six to seven minutes each in a four foot seam, using magnesium ribbon), though they had been preceded by the earliest known cave photographs a month or two previously (Blue John Caverns, Chapel-en-le-frith, Yorkshire) and had been preceded by the earliest known underground photos by almost four years (Paris catacombs and Paris sewers 1861 and 1862).
A much-visited and highly important mining region such as Cornwall is very likely to have seen mines photographed in the early 1850s or late 1840s - keep searching folks!
Establishing dates for earliest known UK surface mining photographs would help write an important footnote to photographic and mining history. For comarison, Richard Calvert Jones is regarded as an internationally important photographic pioneer, not least because he seems to have been the one of the very first photographers to take images of ships (copper ore traders at Swansea, 1847 - reproduced in a great many books). Establishing similar detail for UK mining photographs would be really useful.
Just beware the propensity of some authors to optomistically push dates of early photographs back to dates that are sometimes unlikely. Often, well known and much reproduced early photogrpahs will have been ascribed to a variety of dates by different authors. It is best not to uncritically accept the earliest of a range of dates...