Been past that place a few times over the years, never stopped properly until last autumn. Felt an odd pressure in the chest area when I got close to the north wall, which I've experienced at certain sites before - usually where there's been some kind of intense human activity over a long period. Mills had a brutal history in general, long hours, accidents, kids working in conditions we'd consider horrific now.
What specifically did you feel? And whereabouts on the site were you standing? That matters more than people realise. Some of these locations have very localised spots rather than a general atmosphere across the whole building.
Anyone else who's visited - was it daytime or after dark? I'm generally more interested in daytime reports because you've got fewer variables muddying the water. Night time at an old ruin and your brain is already halfway there before you've even got out the car.