The discharge port size of an ore crusher can vary depending on the model and type of the crusher. Typically, the size is adjustable to accommodate different material sizes and desired output. Commonly, the discharge port size ranges from a few millimeters to several centimeters. To get the specific discharge port size for a particular ore crusher, you would need to refer to the manufacturer's specifications or the operating manual for that model. If you have a specific model in mind, please provide that information for a more detailed response.