Here is an overview from my own knowledge. I suggest you also either listen to the music of Jez Lowe and Ed Pickford/Pigford, the Albion Band's 'Gresford Disaster',or simply read their lyrics. They are both beautiful and brutal. For example, singing of lost youth and slow death through black lung, Ed wrote these first and last verses (hew: cut coal with a pick).

When Ah wes young and in me prime
Ee, aye, Ah could hew!
Whey, Ah wes hewing aal the time
Now me hewing days are through, through, me hewing days are through.

And it's noo ne mair that pit Ah'll see
Ee, aye, Ah could hew!
But Ah carry it roond inside of me.
Now me hewing days are through...

The conditions were atrocious, and the mine-owners, in particular the Vane-Tempest family (Lord Londonderry) were hated with a passion The truck system was abolished by law, so workers had a right to require payment in cash. However...

Miners were 'bound' each year by a hiring fair. They were attracted to a particular mine by a bounty. They either had to buy their own tools, or hire them from the mine owners. They were accommodated in houses owned by the mine-owners and bought their provisions from shops they also owned. They were paid a weekly wage subject to the following deductions (some of many):
Rent.
Hire of lamp.
Sharpening of tools.
Not filling enough coal into their tubs.
Mixing too much stone with the coal.
Cutting coal in too small pieces.
Cutting coal in too large pieces.
Not cutting enough coal in the week (the coal was weighed on a steel yard scale that was...calibrated by the mine owners. It was one of two; the other one came out when the 'weights and measures' man made his visit by appointment: work that one out).

At the end of the week, even without factoring in food and rent, a miner could have worked sixty or seventy hours or more and ended up owing the bastard coal owner money. He could then, of course, get an advance or a loan. Guess who from?

Each time there was a strike, they were evicted and the shops banned from supplying them. "Candymen" and blacklegs (derivation obvious) were brought in, hence the song lyrics

Across the way they stretch a line
To catch the neck and break the spine
Of the dirty blackleg miner.

It is difficult to capture the sheer depth of hatred that still exists in mining communities for those involved.

The conditions were indeed awful, and the word 'damp', from the German 'dampf', was used to mean cjoking gases (choke damp) and explosive gases (fire damp). 'Putters' were employed, from a very, very young age, to push loaded coal tubs along the wagon way from the hewers, who would sit cross legged on a very low home-made wooden seat called a 'cracket' and hew coal by hand, sometimes with their entire upper body laid over to the side. Putters would push the tubs with their heads, and the whole situation can be summed up by one advertisement I saw: "Wanted: Putters for eighteen inch seam"

The eighteen inches refers to the height of the passage they would work in. That's right: pushing a loaded coal tub with their head in a passage eighteen inches from floor to ceiling.

Geordie miners used their own language, called Pitmatic, and one term, 'canny kyevil', which means 'nice cable', is still used to mean comfortable work. It derives from the cable as a measure of length assigned to a particular miner to hew. One free from choke damp, because if you were assigned a seam full of damp you STILL had to work it, or starve.

I could write a hell of a lot more. Meat? In their dreams.