Ngati zomwe zili mu Al2O3 ndizoposa 90%, zimatchedwa njerwa ya corundum. Chifukwa cha zinthu zosiyanasiyana, miyezo ya mayiko osiyanasiyana sikugwirizana kwathunthu. Mwachitsanzo, mayiko a ku Ulaya amanena kuti malire otsika a Al2O3 opangidwa ndi aluminiyamu apamwamba kwambiri ndi 42%. Ku China, njerwa zapamwamba za alumina nthawi zambiri zimatanthawuza njerwa zosakanizika zomwe zili ndi Al2O3 yoposa 48%. Amapangidwa makamaka ndi chilengedwe chapamwamba kwambiri cha bauxite, chomwe chili ndi mchere monga diaspore, bomerite, kaolinite, ndi zina zotero. Dongo lofewa kapena theka-lofewa limawonjezeredwa ku klinker yapamwamba ya alumina monga chomangira kuti ayambe kusakaniza ndi kusakaniza, kenako imapangidwa, yowumitsidwa, ndipo pamapeto pake imathamangitsidwa. The refractoriness wa njerwa mkulu aluminiyamu ndi pafupifupi 1770 ℃, ndi katundu kufewetsa kutentha ndi 1420 ℃-1550 ℃. Common mkulu alumina njerwa ndi LZ-80, LZ-75, LZ-65, LZ-55, LZ-48, etc. Iwo makamaka ntchito akalowa kuphulika ng'anjo, otentha kuphulika ng'anjo, ore-kutentha ng'anjo, magetsi ng'anjo denga, kuphulika. ng'anjo, ng'anjo yoyatsira moto ndi ng'anjo yozungulira. Kuphatikiza apo, njerwa zazikulu za alumina zimagwiritsidwanso ntchito kwambiri ngati njerwa zotsegula zosungira kutentha, mapulagi otsanulira, njerwa za nozzle, ndi zina zambiri.