iPad mini 3 is fully supported with iOS 10.0.0 onwards.

The erasure process for iOS 9.x and earlier, by using overwriting without firmware update:

1. • Go to Settings > iOS and select "Skip 'Apple iOS erasure' if not supported for the device"
   • Select the overwriting standard you wish to use in the drop-down box below this
   • Run factory reset for the device manually, either from device settings or with iTunes. Please refer to manufacturer documentation: https://support.apple.com/en-us/HT201252

• • When the device is in 'Hello' screen, it is ready to be erased with Blancco  Mobile Eraser.