Processes submitted to the queue are picked up by the Batch Launcher. The Batch Launcher is part of the Cúram SDE.
When the Batch Launcher is run, the first thing it does is start the stand alone keyserver - this will be required if any batch process is performing inserts onto the database.
When all the batch processes have executed, the batch launcher will stop the stand alone keyserver.
Note that batch process streaming allows multiple instances of a single batch process to be run in parallel, making full use of the available processing. Batch Process Streaming is covered in more detail in the Batch Streaming guide.