How long can we use a bottle containing anti-bumping granules?

Can it be used indefinitely?

2 answers

You can use them indefinitely.
Just as an added note:
Those anti-bumping granules are great BUT you want to be careful if they are used in quantitative or qualitative analytical work. I have first hand knowledge that some of them (at least the ones I used) contaminated my samples. If you are working with large quantities it is more than likely that small amount of "stuff" will not be noticed but if you are working with trace amounts of elements, that small amount of "stuff" may well be as much or more than the sample had in it to begin with which means the analysis is worthless.