It is not advisable to put any parts of your black walnut tree in the compost bin. This includes the dirt anywhere under the canopy. Just as the juglone poisons the ground around the tree, it will also poison your compost. Using this tainted compost anywhere else would spread the juglone poison. It would most likely kill the plants there and destroy that soil too. Burn any debris from your tree or properly dispose of it through your local refuse station.