Maɗaukakin tubalin alumina nau'in nau'in nau'in abu ne mai siffa wanda aka samar ta hanyar harba yumbu mai jujjuyawa ko wasu albarkatun da ke jujjuyawa a yanayin zafi mai girma; Suna cikin dangin samfurin aluminosilicate. Tubalin da ke jujjuyawa kayan aikin ƙarfe ne waɗanda ba na ƙarfe ba ne waɗanda ake samun su a nau'ikan iri daban-daban, gami da manyan{3} alumina, yumbu, magnesia, corundum, mullite, da tubalin siliki carbide. Saboda mafi girman kaddarorinsu na refractory, manyan bulogin alumina ana amfani da su sosai a tsakanin nau'ikan bulogin da ke juyar da su. Dangane da ma'auni na manyan{7}}alumina refractory kayan, abun ciki na Al₂O₃ shine babban ma'aunin rarrabuwa. Musamman, manyan bulogin alumina suna kasassu zuwa maki uku: Grade I ( abun ciki na Al₂O₃> 75%), Grade II (abun ciki na Al₂O₃ tsakanin 60% da 75%), da Grade III (Al₂O₃ tsakanin 48% da 60%).
A matsayin nau'in abu mai jujjuyawa, manyan bulogin alumina na farko sun ƙunshi Al₂O₃. Idan aka kwatanta da tubalin yumbu da ɓangarorin silica na yumbu, manyan tubalin alumina suna nuna mafi girman juzu'i don haka ana rarraba su azaman manyan kayan refractory-. Babban abun ciki na su na Al₂O₃ yana ba su kusa{6} halaye na tsaka tsaki, yana ba da damar juriya mai tasiri ga zaizayar ƙasa ta ɓangarorin acidic da na asali. Koyaya, yana da mahimmanci a lura cewa duk da ƙunshe da SiO₂, juriyarsu ga slag na asali ya ɗan yi ƙasa da juriya ga slag acid. Dangane da abun ciki na Al₂O₃, tubalin alumina masu girma- ana iya ƙara raba su zuwa maki kamar 55, 65, 75, da 80.
An rarraba manyan tubalin alumina zuwa maki daban-daban dangane da abun cikin su na Al₂O₃ (aluminum oxide). Daga cikin su, tubalin corundum{2} tare da abun ciki na aluminium na 90% ko sama - suna wakiltar mafi girman matakin bulogin alumina-. "Ma'auni na musamman" mai girma - tubalin alumina ya ƙunshi aƙalla kashi 85% na aluminium, yayin da tubalin Grade I ya ƙunshi fiye da 75%; Tubalin digiri na II da na III sun ƙunshi aƙalla 65% da 55% na aluminum, bi da bi. Waɗannan ma'auni daban-daban suna ba da kaddarorin kaddarorin daban-daban don biyan buƙatun masana'antu iri-iri. Maɗaukakin tubalin alumina nau'in samfuri ne na aluminosilicate mai jujjuyawa da abun ciki na aluminum oxide (Al₂O₃) ya wuce 48%. Lokacin da abun ciki na Al₂O₃ ya kai kashi 90% ko sama da haka, ana rarraba su azaman tubalin corundum{18}}ananan bulo na alumina iri-iri wanda ke ba da aiki na musamman. Yana da kyau a lura cewa ma'auni don manyan tubalin alumina na iya bambanta a cikin ƙasashe saboda bambance-bambancen albarkatun da ake da su.
Misali, a cikin kasashen Turai, mafi ƙarancin abun ciki na Al₂O₃ don babban{0}}alumina refractory kayan an saita zuwa 42%. A kasar Sin, duk da haka, manyan bulogin alumina yawanci ana rarraba su zuwa maki uku: Tulin Grade I ya ƙunshi fiye da 75% Al₂O₃; Tubalin digiri na II ya ƙunshi tsakanin 60% da 75% Al₂O₃; da tubalin Grade III sun ƙunshi tsakanin 48% zuwa 60% Al₂O₃.