While the majority of pulp is made in digesters, there is also ground-wood pulp which is made by grinding wood (that aforementioned naming process).
This involves a spinning stone drum, water, a hydraulic ram, logs, and lots of steel cage-work - the ram shoves the log against the spinning drum, and water washes the pulp away. Sometimes the logs fracture, splinter, or break free from the ram, and then you have bouncing logs inside the steel cage.
It’s slow, and the groundwood pulp needs some further processing, but it is still used for some purposes.
Groundwood is used a lot in newsprint and coated magazine paper. It’s a high yield pulp, you get a lot of pulp per ton of wood, especially compared to bleached chemical pulps, where you end up with less than half a ton of pulp per ton of wood. The lignin isn’t removed from groundwood pulps, that’s why if your newspaper sits in your driveway for a couple of hours it turns noticeably yellow, ultraviolet light generates a lot of chromophores in lignin.
