Q1: Dab tsi yog cov kauj ruam tseem ceeb hauv kev hloov bauxite rau alumina?
Bauxite ore raug crushing thiab sib tsoo ua ntej nkag mus rau hauv cov txheej txheem Bayer. Nws yog tov nrog kub sodium hydroxide (caustic soda) kom yaj aluminium hydroxides rau hauv sodium aluminate. Insoluble impurities (liab av) lim tawm, thaum lub aluminate tov yog txias thiab noob los precipitate ntshiab alumina hydrate. Cov hydrate no yog calcined ntawm 1,100℃los tsim cov alumina anhydrous (Al₂O₃). Txhua tonne ntawm alumina yuav tsum tau 2-3 tonnes ntawm bauxite thiab generates 1-1.5 tonnes ntawm liab av nkos residue.
Q2: Vim li cas Hall -Héroult txheej txheem tseem ceeb rau kev tsim khoom txhuas?
Txoj kev electrolytic no decomposes alumina rau hauv molten aluminium siv carbon anodes. Dissolved alumina nyob rau hauv molten cryolite undergoes electrolysis ntawm 950 degree, tso oxygen uas reacts nrog carbon anodes los ua CO₂. Aluminium ions migrate mus rau cathode, ua kua hlau pas dej ua ke. Cov hlwb niaj hnub ua haujlwm ntawm 4-5 volts thiab 150, 000+ amperes, ua tau ~ 2 tonnes ib hnub. Inert anode kev tshawb fawb aims los hloov carbon anodes kom tshem tawm CO₂ emissions.
Q3: Yuav ua li cas smelters tswj lub zog noj?
Hluav taws xob suav nrog 30-40% ntawm cov nqi tsim khoom vim yog 12-15 kWh / kg zog siv. Smelters nrhiav nyob ze ntawm lub pas dej da dej kom muaj zog txaus; Iceland cov nroj tsuag siv 100% geothermal zog. Advanced "potline" tsim rov qab cov cua sov pov tseg rau hauv cheeb tsam cua sov. Smelter efficiency yog ntsuas los ntawm "tam sim no efficiency" (feem ntau 90-95%), qhia tias hluav taws xob tam sim no ua tau txhuas. Digital ntxaib technology tam sim no optimizes real-time zog siv.
Q4: Dab tsi tiv thaiv ib puag ncig muaj rau cov av nkos liab?
Cov av nkos liab (pH 10-13) muaj hlau, titanium, thiab cov hlau hnyav. Qhuav- stacking nyob rau hauv lined impoundments tiv thaiv cov dej hauv av. Neutralization nrog seawater los yog CO₂ txo alkalinity. Upcycling teg num muaj xws li extracting scandium rau alloys, siv nws nyob rau hauv cement ntau lawm, los yog hloov mus rau hauv cib. Cov txheej txheem xoom pov tseg tshiab rov qab 95% ntawm alkali los ntawm cov av nkos liab rau rov siv dua.
Q5: Yuav ua li cas anode cuam tshuam thaum lub sij hawm electrolysis?
Cov teebmeem anode tshwm sim thaum alumina concentration poob qis dua 1-2%, ua rau lub zog hluav taws xob thiab PFC emissions. Tsis siv neeg pub khoom noj kom pom cov qib alumina zoo (2-3%). Point feeders txhaj alumina precisely thaum voltage tshaj 8 volts. Niaj hnub smelters txo PFC emissions rau<0.1 tonnes CO₂e per tonne of aluminum using these systems.
