You can use a Resource object to model the unplanned failures and repairs of a crusher or conveyor. The Resource object has unplanned failures built in, and furthermore, can accommodate a shift pattern.
When the resource fails, close the flow node and when it is repaired, open the flownode again.
I have modified your model to illustrate this concept.
There was custom Flow Library shared in the past that contains a "flow server". Basically an object such as a server, but that can handle flow.