Low carbon aluminum production method using single furnace carbothermic reduction operated in batch mode
View Patent ↗A batch process for producing low carbon aluminum using a single carbothermic reactor furnace is disclosed in which the slag making, metal making and carbon extraction is carried out in a single furnace, single compartment reactor. The Al 2 O and Al vapors generated in slag making and metal making steps are recovered in a vapor recovery reactor, and treated with a carbonaceous material to produce recyclable material comprising Al 4 C 3 . The recyclable material is used to assist with one or more subsequent slag making steps.
1. A batch carbothermic method of producing low carbon aluminum, the method comprising:
(a) producing a first mixture in a single furnace reactor having a single reactor compartment and a plurality of resistance heating electrodes, wherein the first mixture comprises slag and solid aluminum carbide;
(b) forming in the single furnace reactor an upper Al—C alloy phase and a lower slag phase from the first mixture;
(c) extracting carbon from the upper Al—C alloy phase into the lower slag phase via addition of aluminum oxide to the single furnace reactor;
(d) removing at least a portion of the upper Al—C alloy phase from the single furnace reactor;
(e) collecting, during at least one of the producing and forming steps, off-gas from the single furnace reactor in an external vapor recovery reactor, the off-gas comprising at least one vapor species of Al 2 O, Al and CO;
(f) adding, concomitant to the collecting step, a carbonaceous material to the external vapor recovery reactor, thereby forming a recyclable material, the recyclable material comprising Al 4 C 3 , and
wherein the producing step comprises:
(g) feeding the recyclable material from the vapor recovery reactor to the single furnace reactor to assist in the production of the first mixture.
2. The method of claim 1 , wherein the collecting step (e) occurs during both the producing step (a) and the forming step (b).
3. The method of claim 1 , wherein the forming step (b) occurs without utilizing the recyclable material in the single furnace reactor.
4. The method of claim 1 , wherein, after the extracting step (c), the Al—C alloy contained in the single furnace reactor comprises less than 5% carbon by weight.
5. The method of claim 1 , wherein, after the extracting step (c), the Al—C alloy contained in the single furnace reactor comprises less than 3% carbon by weight.
6. The method of claim 1 , wherein the feeding step (g) further comprises:
adding concomitant to the producing step (a), at least one of Al 2 O 3 and C to the single furnace reactor.
7. The method of claim 1 , wherein the collecting step (e) occurs during at least one of the extracting and removing steps.
8. The method of claim 1 , wherein the collecting step (e) occurs during both of the extracting and removing steps.
9. The method of claim 1 , wherein the recyclable material comprises slag and Al 4 C 3 .