CMMMech > Secondary resource > Spent indium-tin oxide targets

Spent indium-tin oxide targets secondary resource

Spent indium-tin oxide targets are a solid secondary resource associated with sputtering-target use, distinct from elemental indium or tin, virgin ITO products, LCD glass panels and dissolved etching wastewater. Gu and colleagues identify their supplied Wako material as spent ITO target material and analyze its ground powder. The specific prior sputtering history and service conditions are not documented in the accessible main article, so the spent designation is retained as the study's feed description. Its mixed oxide composition and impurities are sample-specific, not a universal target specification. No criticality designation is inherited from constituent elements.

Microbial & Biochemical Mechanisms (1)

Laboratory acid dissolution followed by chloride dehydration and fractionation

recovery

Ground spent ITO material was dissolved in hydrochloric acid, followed by distillation to obtain mixed chloride hydrates, thionyl-chloride dehydration, and fractionation to separate tin tetrachloride from solid indium chloride. The main article reports isolated product fractions and identifies the solid indium chloride by X-ray diffraction; this endpoint extends beyond aqueous metal solubilization. Product purity and whole-process recovery percentages are not adopted here because relevant supplementary assays were unavailable and numerical reporting requires reconciliation. No microbial step or industrial operation was demonstrated.

Experimental Context & Analytical Limits:
The laboratory feed was crushed and milled Wako spent target material. The selected leaching condition was 5 mol/L HCl, 10 g/L solid loading, 40 degrees C, 500 rpm and 120 min. The main article describes rotary evaporation in a 90 degrees C oil bath for 2 h with a reported vacuum degree of 0.09 MPa, without converting that ambiguous pressure description to absolute pressure. Mixed hydrates were treated with 1.2 mL thionyl chloride per gram of hydrate under reflux at 75 degrees C for 2 h, then fractionated using a Vigreux column. Table 3 reports three parallel full-process experiments with approximately 5 g feed charges. This is gram-scale laboratory evidence; its separate comparison normalized to 1 kg is not a demonstrated kilogram-scale run. No acid-free control is described. Particle-size distribution and additional feed measurements depend on the unavailable supporting information.

Curated Evidence Points:

Support Source: gu2017

Sections 2.1-2.3 and 3.1-3.3 support the laboratory sequence; Figure 1 shows leaching comparisons, Figure 4 identifies the isolated solid as anhydrous InCl3, and Table 3 reports product masses for three runs. Separation relies on the distinct solubility and volatility of the chlorides and thionyl chloride; this is chemical processing, not biological extraction. The support is for the observed product separation, not a claim of complete recovery or universal applicability to all ITO wastes.

Partial Source: gu2017

Table 1 presents XRF oxide mass fractions alongside ICP entries labelled as ions with nearly matching percentages; their normalization cannot be resolved without supplementary Table S1. Tin recovery is described differently in the abstract, section 3.3 and conclusion. Supplementary Table S5 underlies purity claims, and Tables S3 and S6-S8 underlie process comparisons; these were not inspected. Table 4 labels energy consumption in kW, so it is not accepted as a verified energy balance. Reagent reuse, lower environmental impact, commercial economics and scalability remain author proposals or comparisons, not demonstrated closed-loop operation, lifecycle assessment or deployment.

Sources & References

gu2017: Gu S, Fu B, Dodbiba G, Fujita T, Fang B (2017). A sustainable approach to separate and recover indium and tin from spent indium-tin oxide targets. RSC Advances 7:52017-52023. DOI 10.1039/C7RA11976C. Complete seven-page main article: sections 2.1-2.3 and 3.1-3.3, Tables 1-3, Scheme 1 and Figures 1-4. Supporting information was not obtained; supplementary composition, physical characterization, purity and process-comparison details remain unverified.
https://doi.org/10.1039/C7RA11976C (accessed 2026-10-16)

Curation History

Timestamp	Curator	Action	Summary
`2026-10-16T08:07:01Z`	codex (GPT-6; codex)	CREATE	Created a distinct spent target secondary-resource record with primary laboratory chloride-separation evidence and explicit unavailable supplementary assays and numerical limits.

Record source: data/records/spent-ito-targets.yaml