Secondary aluminium dross secondary resource
Heterogeneous residual aluminium dross after an earlier recovery of metallic aluminium from primary dross by screening or flux-assisted remelting. This source-defined secondary dross is narrower than the umbrella aluminium-dross category; the accepted specimen came from an aluminium remelting plant in Guangxi, China. It contains metallic aluminium, aluminium oxides and nitride, magnesium-aluminium spinel, and other oxides and process salts. It is not a mineral species, elemental aluminium, bauxite residue, spent potlining, or an automatically equivalent feed to an unspecified aluminium-smelting slag. Laboratory chemical extraction is documented without a microbial mechanism, inherited criticality designation, or demonstrated industrial deployment.
Microbial & Biochemical Mechanisms (1)
Abiotic roasting and caustic extraction from secondary aluminium dross
separation
Alkali-assisted roasting altered the mixed dross to sodium-aluminate-rich clinkers that were subsequently leached with caustic liquor. Before/after diffraction and solid compositions support aluminium mobilization and residual insoluble phases. The reported recovery is a magnesium-normalized clinker-to-residue estimate, not an independently closed original-waste mass balance or an isolated aluminium or alumina product yield.
Experimental Context & Analytical Limits:
The real plant specimen is characterized in Section 2.1, Figure 2 and Table 1, including 38.23 wt.% total Al; this is not its metallic-Al fraction. Section 2.2 used 100 g dross mixed with alkali, dry pressed at 30 MPa into cylinders 20 mm in diameter and 40 mm long. Samples were heated in a corundum crucible in air at 10 degrees C/min, held for 1 h, cooled in a desiccator, crushed through 200 mesh, and leached; residues were filtered and repeatedly rinsed with boiling water. The final condition stated in the abstract and Section 3.5/Table 4 is 1150 degrees C roasting, Na2CO3/Al2O3 molar ratio 1.3, followed by 90 degrees C leaching for 30 min at liquid-to-solid ratio 10 mL/g. Section 2.2 states 60 g/L caustic, while Table 2 expresses this as C(Na2O) and lists alpha_k = 3.0 without a complete liquor preparation recipe. The Table 2 carbonate-ratio series instead specifies 1100 degrees C roasting and 60 min leaching. These distinct source conditions are retained rather than collapsed into one unqualified reproduction protocol. No cells, microbial products or biological treatment arm were used.
The real plant specimen is characterized in Section 2.1, Figure 2 and Table 1, including 38.23 wt.% total Al; this is not its metallic-Al fraction. Section 2.2 used 100 g dross mixed with alkali, dry pressed at 30 MPa into cylinders 20 mm in diameter and 40 mm long. Samples were heated in a corundum crucible in air at 10 degrees C/min, held for 1 h, cooled in a desiccator, crushed through 200 mesh, and leached; residues were filtered and repeatedly rinsed with boiling water. The final condition stated in the abstract and Section 3.5/Table 4 is 1150 degrees C roasting, Na2CO3/Al2O3 molar ratio 1.3, followed by 90 degrees C leaching for 30 min at liquid-to-solid ratio 10 mL/g. Section 2.2 states 60 g/L caustic, while Table 2 expresses this as C(Na2O) and lists alpha_k = 3.0 without a complete liquor preparation recipe. The Table 2 carbonate-ratio series instead specifies 1100 degrees C roasting and 60 min leaching. These distinct source conditions are retained rather than collapsed into one unqualified reproduction protocol. No cells, microbial products or biological treatment arm were used.
Curated Evidence Points:
Support
Source:
lv2022
Sections 2.1-2.3, Figures 2 and 6-7, and Tables 1 and 4 support a mixed industrial feed and altered roasted/residual assemblages. Sodium aluminate is assigned in the clinkers; magnesium oxide, residual spinel and aluminium-silicate phases remain in the residues. These source-assigned phases do not establish quantitative conversion of every original Al host or product purity. The generic introductory low metallic-Al description of secondary dross is distinct from the specimen's 38.23 wt.% total elemental Al.
Support
Source:
lv2022
Section 3.2.1, the carbonate-ratio panel Figure 5d, Section 3.5/Table 4 and Conclusions report 90.79% Al and 92.03% Na recovery for the selected carbonate route. Section 2.3 derives recovery from XRF compositions of roasted clinkers and leaching residues using their Mg ratio. This relies on magnesium as a conserved solid tracer; Equations 1-2 also have incomplete printed brackets. These are source-reported solid-balance estimates, not directly measured solution inventory or overall original-dross-to-product recovery. Added sodium carbonate and caustic contribute sodium, so the Na value is not recovery of sodium initially present in the waste. Figure 8a shows a rapid initial increase and a later plateau; higher liquid-to-solid ratios beyond 10 mL/g give little further improvement in the separate 60 degrees C Figure 8b series.
Partial
Source:
lv2022
Section 3.2.1 reports slightly higher selected extraction with NaOH but rejects it for subsequent work because moisture uptake caused AlN hydrolysis, ammonia release and collapse of the pressed samples into slurry. No quantitative ammonia comparison or untreated-dross leaching control is presented, and no independent replicate counts or error bars are specified. Figure 5's caption interchanges the descriptions of panels b and c relative to their axes and plotted alkali labels; Table 2 and the final optimized recipe also differ. Figure 7's caption calls the varied ratios mass ratios, whereas its labels and the text use n(N/A). The XRD method states a 10-60 degree scan, while the initial-feed Figure 2 extends to 90 degrees. These reporting limits preclude a uniquely reconstructed protocol or an unqualified global optimum.
Partial
Source:
lv2022
Sections 3.4-3.5 and Figures 8-11 provide fitted kinetics, thermal curves and selected microscopy/EDS, not unique proof of a controlling molecular step. The reported 9.69 kJ/mol activation energy and layer-diffusion interpretation remain model dependent. Lower N and Cl concentrations in Table 4 do not alone close a gas or total-mass balance after reagent addition; neither recovered condensate purity nor complete environmental detoxification is established. The source alternates chlorate and chloride terminology despite a chloride-ion assay. Figure 1's alumina-production endpoint is a process proposal; the Conclusions leave desilication and crystal-seed decomposition for future work, so no isolated alumina product is claimed here.
Sources & References
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lv2022: Lv, Xie, Wu, Li, Yang, Han, Liu and Zhao (2022). Effective Extraction of the Al Element from Secondary Aluminum Dross Using a Combined Dry Pressing and Alkaline Roasting Process. Materials 15(16):5686. DOI 10.3390/ma15165686. Complete 16-page original, Sections 1-4, Figures 1-11 and Tables 1-4; published 18 August 2022.
https://doi.org/10.3390/ma15165686 (accessed 2026-10-15)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-15T03:51:53.820238Z |
Codex (GPT-6; Codex) | CREATE | Created a post-metal-recovery secondary aluminium dross resource using the complete original laboratory study. Preserved mixed-feed identity, source recipe and graphical conflicts, Mg-normalized extraction denominators, missing product balances and the absence of microbial treatment. |
Record source: data/records/secondary-aluminium-dross.yaml