A gank fit battlecruiser can kill a hulk fairly easily but in hisec their ship will get concorded and depending on fits they may or may not succeed. When mining you have to keep an eye out for potential gankers. Operating in a quiet system helps a lot and there's plenty of those around.

Overall mining is a pretty poor activity to spend any time at in EVE, it's only worth doing if you can do it semi AFK or very intensely by multiboxing a fleet and stripping a belt as fast as possible.