When you get hard beans like that, just add a pinch of baking soda and cook a while longer. The soda will soften them right up, but don't use too much or they'll turn to mush, lol...ask me how I know.

You might start with a little pinch and if they haven't gotten soft enough after a little while add a little more. After the first time, you'll know for sure how much the next time. It's an old country trick, but I've never seen it fail.
Pressure cooking works too, but I'll let oldmania answer jmtinmi's question directly. From my experience, I have a 4-quart cooker. I cook 1 pound of pinto beans at a time, rinse, add a few chunks of ham or salt pork and about a tablespoon of bacon grease (hey, I never said they were healthy, lol) and fill my pot to about the halfway mark. Pressure cook at 15 pounds for 25-30 minutes, and they're done. I don't salt or anything until they're done.
The general rule for pressure cookers is to never fill them more than 2/3 full and only about 1/2 for beans, as they tend to foam up and block the vent tube. Hwever, adding oil of some sort to the cooking water helps prevent that also.
I wouldn't waste lots of energy or days of work on hard beans either, but it's a quick and easy fix and might come in handy some day if that pound of beans is hard to come by. Good luck!