Iinkqubo zokupholisa ukuntywiliselwa ngolwelo zisebenzisa ulwelo olungaqhubekiyo ukupholisa izixhobo zombane, ezifana ne-oyile yeminerali okanye incindi yokugquma.Ulwelo luhlala lugcinwe kwitanki okanye kwenye inkqubo etywiniweyo.Isixhobo sombane silungiselelwa ukuntywiliselwa ngenkqubo yokuntywiliselwa emva koko sintywiliselwe kulwelo kwaye sipholiswe yinkqubo yokutshintsha ubushushu.