Ukukhiqizwa kwe-aluminium sulfate-izinto zokusetshenziswa, i-aluminium trihydrate

I-aluminium sulfate (Al2(SO4)3), evame ukubizwa ngokuthi i-alum, ikhiqizwa njengamakristalu amhlophe angashi futhi ancibilikayo emanzini. Le hydrate eyomile (Al2(SO4)3.14H2O) ingu-17% Al2O3 futhi ithengiswa njengesixazululo se-aluminium sulfate esingu-47% w/w esingu-8% Al2O3. Iphinde ithengiswe ngesimo esiqinile njenge-mashed, i-ground noma uthuli.

I-aluminium sulfate, i-Al2(SO4)3, isetshenziswa kabanzi embonini. Ukusetshenziswa kwayo okuvame kakhulu kusembonini ye-pulp kanye nephepha kanye nasekuhlanzweni kwamanzi. I-aluminium sulfate ibilokhu isetshenziswa ngumuntu kusukela ngo-2000 BC, lapho abaseGibhithe besebenzisa i-mineral alum njenge-mordant ekudayini. Sekuyisikhathi eside isetshenziswa ngobukhulu bephepha ukuthuthukisa ukuqina kanye nokwamukelwa kweyinki kanye nokwelashwa kwamanzi ukuze kucwengisiswe amanzi. Okunye ukusetshenziswa kwe-alum kufaka phakathi ukwelashwa kwamanzi amdaka, njenge-ejenti yokuvimbela amanzi kanye ne-accelerator kukhonkolo, njenge-clarifier yamafutha namafutha kanye ne-ejenti yokukhipha amagwebu omlilo.

I-Alum (njengoba ivame ukubizwa kanjalo i-aluminium sulfate) yenziwa ngenqubo elula enezinyathelo ezimbili kusukela ku-aluminium trihydrate kanye ne-sulfuric acid ngokuya ngokulandelayo:

2Al(OH)3 + 3H2SO4 + 8H2O → Al2(SO4)3 .14H2O ∆fH = -156 kJ mol-1

Isinyathelo sokuqala sihilela ukuxuba izithako ku-reactor, kanti esesibili inqubo yokuchoboza izinto ukuze kwenziwe izinhlobo ezahlukene ze-alum eqinile ethengiswayo.

Ama-Raw material

I-aluminium trihydrate ihlanzwa kusuka ku-bauxite. Ama-deposit e-bauxite ebhizinisi (30-75% Al2O3) ayenzeka e-Australia, eJamaica, eFrance, eGuyana, eGuinea, e-USA naseBrazil. I-Bauxite ore incibilikiswa ku-caustic soda enamandla ukuze kwakheke i-sodium aluminate. I-aluminium trihydrate ibe isiba yi-neutralization (ngokuvamile nge-carbon dioxide) noma nge-autoprecipitation (inqubo ye-Bayer). Enye into eluhlaza, i-sulfuric acid, yenzelwe ukukhiqizwa kwe-superphosphate kwa-Farmers Fertiliser Ltd. I-asidi ifika nge-road tanker bese ipompelwa emathangini okugcina.