Italian to English Tech/Engineering Mining & Minerals / Gems

I'm wondering if this is the same word in English - when I googled it, the only references I found were on Italian sites, some of them very poorly translated into English. Context follows:

La nefelina grado vetro viene stoccata in tramoggia dedicata e da qui tramite trasporto a nastro coperto fino al mulino con carica macinante in sfere di allubit da 1'1/2.