how many shareholders to block merger

As everybody knows, the Sapex board has recommended merger with Linc, with conditions that most Sapex shareholders see as unfavourable to them.

I believe that the board has to get share-holder approval, as stated in Sapex's report:

The Schemes also require Court approval in accordance with 411(4)(b) of the Corporations Act, and the approval of shareholders and option holders of SAPEX.

How many percent of the shareholders in Sapex have to vote for this proposal for it to be passed. In other words, how many percent do we need voting against the proposal for it to be consigned to the rubbish-bin, where it rightfully belongs?