3.It is shown that expansible ettringite forms in the topochemical reaction,and crystallizes in-situ on the surface of unhydrated aluminate minerals and orients radially.
4.Modified calcium aluminate as a purifying agent, with two functions both of coagulability and desaltification, can be produced from industrial waste slag from alumina plant.
2.Strontium aluminate is more expensive, but it has a longer persistence, which means it emits visible light more slowly, and glows longer after being energized.