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Spent copper-zinc-alumina catalyst secondary resource

Used CuO-ZnO-Al2O3 catalyst material from synthesis-gas processing, including low-temperature carbon monoxide conversion. This composition-defined secondary resource is distinct from fresh catalyst, its constituent oxides, elemental copper/zinc and spent refinery hydroprocessing catalysts. The selected Polish-market sample had 35.1 wt% Cu, 29.9 wt% Zn and 9.2 wt% Al by AAS; these are sample measurements, not a universal formulation. Its plant and service history are unspecified. No constituent criticality is inherited.

Microbial & Biochemical Mechanisms (2)

Laboratory coal reduction with slag-forming additions

recovery

Coal-assisted melting produced a copper-rich alloy, with substantial copper remaining outside the alloy. Zinc transfer to dust was inferred from an incomplete balance, not measured as a collected zinc product.

Experimental Context & Analytical Limits:
Four laboratory variants used 100 g uncrushed spent catalyst and 10 g coal in graphite crucibles, with different SiO2/CaO/NaOH/Na2CO3 additions. Variant I used 50 g SiO2 and 15 g CaO at 1300 degrees C for 45 minutes; variants II-IV used 1250-1300 degrees C for 50-90 minutes. Graphite also provided reducing conditions.
Curated Evidence Points:
§§3.1-3.2 and Table 1: variant I yielded 26 g alloy containing 23.2 g Cu and 2.5 g Zn; 66.1% of feed Cu entered alloy. Reported Cu-to-alloy yields across four arms were 50.4-66.1%. Copper also remained in slag, and unmelted fines were observed in variants I/II. The alloy is not pure copper, and arms must not be pooled.
Table 1 labels the unbalanced zinc remainder as dust and gives 68.2-71.6% yield, but §3.2.1 states its amount could not be identified and §5 describes the zinc-dust yield as estimated from the alloy/slag difference. Unmelted fractions are omitted from that table. These values do not establish isolated zinc recovery or a closed mass balance. Viscous slag and copper losses limited the tested routes; industrial throughput and emissions performance were not demonstrated.

Sequential alkaline zinc and acid copper leaching

separation

Sequential NaOH and H2SO4 leaching separated aqueous zinc and copper fractions from a zinc-aluminate/carbon residue. Reported overall metal accounting includes retained solids and must not be read as isolated-metal recovery.

Experimental Context & Analytical Limits:
Feed was fragmented below 90 micrometres. NaOH at 200 g/dm3, 75 degrees C for 120 minutes preceded H2SO4 at 180 g/dm3, 60 degrees C for 120 minutes; both used the reported liquid/solid ratio 10, whose units are not specified. A small, unquantified H2O2 addition was used during acid leaching. Each stage was filtered; fine particles made filtration difficult.
Curated Evidence Points:
§§4.1-4.2 and Figure 4: the 100 g laboratory feed produced separate 0.8 dm3 liquids, reported at 23 g/dm3 Zn and 43 g/dm3 Cu, plus 33 g residue. The reported balance assigns 18.5 g Zn (61.9%) and 34.5 g Cu (98%) to leachates. Volume-times-concentration differs slightly from rounded balance masses. Residue diffraction identifies ZnAl2O4 and carbon; air heating at 600 degrees C removed about 10% of residue mass.
The stated 97.5% Zn and 96% Al overall yields count zinc/aluminium retained in residue as products, whereas only 61.9% Zn was reported leached. Residue was not established as pure zinc aluminate, and no downstream electrolysis, precipitation, catalyst reuse or isolated metal yield was demonstrated. The unknown peroxide dose and undefined liquid/solid units limit reproduction. The §4.1 statement about insoluble copper/zinc oxides is inconsistent with the reported aqueous separation and residue analysis; the narrower measured fractions are retained. Laboratory tests do not establish a waste-free industrial process.

Sources & References

  1. malecki_2018: Małecki and Gargul (2018). Low-Waste Recycling of Spent CuO-ZnO-Al2O3 Catalysts. Metals 8(3):177. DOI 10.3390/met8030177; complete published eight-page PDF, §§2-4, Table 1, Figures 1-4.
    https://doi.org/10.3390/met8030177 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T22:14:11.578484+00:00 Codex (GPT-6; Codex) CREATE Created a distinct spent-catalyst resource with source-scoped abiotic laboratory evidence and explicit yield, composition and scale limits.
2026-10-15T22:21:05.307363+00:00 Codex (GPT-6; Codex) EDIT Corrected nonexistent table/section locators and attributed the inferred zinc-dust balance to the actual source passages.

Record source: data/records/spent-copper-zinc-alumina-catalyst.yaml