Zinc leach residue secondary resource
Mixed residual solids from acid leaching in zinc hydrometallurgy, including zinc retained in ferrite, sulfide and other specimen-dependent phases. The accepted studies used separate industrial residues from Hunan and Yunnan, China; their compositions and treatment outcomes are not interchangeable. This processing-generated resource is distinct from elemental zinc, a pure zinc-ferrite phase, zinc calcine before leaching, and zinc-purification waste. Two laboratory abiotic treatments are documented. No criticality designation, microbial mechanism, isolated zinc-product yield or deployment of these particular experimental protocols is inferred.
Microbial & Biochemical Mechanisms (2)
Abiotic copper-assisted acid leaching of a Hunan zinc leach residue
separation
Adding metallic copper increased aqueous zinc extraction relative to the same sulfuric-acid treatment without copper. The authors interpret this as reductive dissolution of zinc ferrite; the industrial-feed experiment measures solution concentrations and residual solids, not a purified zinc product or an independently established molecular rate-limiting step.
Experimental Context & Analytical Limits:
Sections 2.1-2.3 used a residue from an unnamed Hunan zinc smelter, reported as 17.30 wt.% Zn and 25.20 wt.% Fe, with zinc ferrite and minor lead sulfate assigned by XRD. Its D10/D50/D90 were 4.39/23.77/60.99 micrometres; the separate calcine's sieving protocol is not transferred to this feed. Reagent copper powder was 200 mesh and 99.7% purity. Batch tests used 4 mL sulfuric-acid solution in 50 mL centrifuge tubes, perforated film allowing air contact, 240 rpm and 60 min. The matched comparison used 60 degrees C, 100 g/L H2SO4, 20 mL/g liquid-to-residue ratio, and copper addition 21.60% of residue mass or no copper. Products were centrifuged at 5000 rpm for 2 min; solids were washed three times with 10 mL water and freeze-dried for 12 h. Solution metals were assayed by ICP-OES. No organism, biomass or biological reagent was used.
Sections 2.1-2.3 used a residue from an unnamed Hunan zinc smelter, reported as 17.30 wt.% Zn and 25.20 wt.% Fe, with zinc ferrite and minor lead sulfate assigned by XRD. Its D10/D50/D90 were 4.39/23.77/60.99 micrometres; the separate calcine's sieving protocol is not transferred to this feed. Reagent copper powder was 200 mesh and 99.7% purity. Batch tests used 4 mL sulfuric-acid solution in 50 mL centrifuge tubes, perforated film allowing air contact, 240 rpm and 60 min. The matched comparison used 60 degrees C, 100 g/L H2SO4, 20 mL/g liquid-to-residue ratio, and copper addition 21.60% of residue mass or no copper. Products were centrifuged at 5000 rpm for 2 min; solids were washed three times with 10 mL water and freeze-dried for 12 h. Solution metals were assayed by ICP-OES. No organism, biomass or biological reagent was used.
Curated Evidence Points:
Support
Source:
zhang2024
Section 3.2/Figures 1-3 and Conclusions report zinc extraction of 92.82% with copper versus 32.82% without it under the matched conditions, calculated from solution zinc relative to initial feed zinc. The corresponding residual-solid rates were 25.20% and 62.34%. Equation 2 subtracts an estimated unreacted copper contribution from weighed solids, so these are source-defined copper-corrected residual rates, not a complete waste or metal balance. Copper changes the aqueous metal inventory as well as zinc dissolution; the source does not isolate a zinc product.
Partial
Source:
zhang2024
Figure 4 and Table 1 retain a reagent-demand tradeoff: 90.47% zinc extraction is reported at 100 g/L acid and 15 mL/g, versus 96.30% at 200 g/L and 30 mL/g, each at 60 degrees C for 60 min with 21.60% copper. Higher extraction is not evidence of less reagent use. Section 2.3 records pH below zero as zero; plotted zero values are censored, not exact pH measurements. Replicate counts and uncertainty are not supplied for these curves. The galvanic/valence explanation in Section 3.1 invokes a separate zinc-ferrite study; no such molecular mechanism is independently established for every phase in this mixed residue. The separate calcine results and proposed industrial implementation are excluded.
Abiotic anthracite-assisted redox smelting of a Yunnan zinc leach residue
redox transformation
Laboratory heating with anthracite in flowing air altered zinc-bearing phases and reduced the zinc inventory remaining in slag. XRD and spatial EPMA observations support changing sulfide, oxide and silicate assemblages. The proposed oxidation, dissolution into molten slag and subsequent reduction/volatilization pathway is an interpretation of these observations; collected zinc vapor or dust was not quantified.
Experimental Context & Analytical Limits:
Sections 2.1-2.4/Table 1 used a different Yunnan smelter residue with 14.51 wt.% Zn, 21.34 wt.% Fe and 8.70 wt.% S. Figure 1 identifies zinc ferrite, zinc sulfide, calcium sulfate and quartz; reported chemical extraction fractions refer to the allocation of total Zn, not bulk mineral mass fractions. Dried residue was ground below 74 micrometres and mixed with anthracite, whose Table 2 fixed-carbon and ash contents were 59.42 and 30.58 wt.%. The clearly cross-referenced condition is 17.5 wt.% anthracite relative to residue, 1623 K and a 90 min hold. A laboratory furnace heated cylindrical crucibles at 10 K/min under dry air at 300 mL/min, followed by cooling to 1273 K within 5 min and water quenching to 298 K. The separate zero-minute series still includes heating to the target temperature. No biological treatment was used.
Sections 2.1-2.4/Table 1 used a different Yunnan smelter residue with 14.51 wt.% Zn, 21.34 wt.% Fe and 8.70 wt.% S. Figure 1 identifies zinc ferrite, zinc sulfide, calcium sulfate and quartz; reported chemical extraction fractions refer to the allocation of total Zn, not bulk mineral mass fractions. Dried residue was ground below 74 micrometres and mixed with anthracite, whose Table 2 fixed-carbon and ash contents were 59.42 and 30.58 wt.%. The clearly cross-referenced condition is 17.5 wt.% anthracite relative to residue, 1623 K and a 90 min hold. A laboratory furnace heated cylindrical crucibles at 10 K/min under dry air at 300 mL/min, followed by cooling to 1273 K within 5 min and water quenching to 298 K. The separate zero-minute series still includes heating to the target temperature. No biological treatment was used.
Curated Evidence Points:
Support
Source:
wang2026
Sections 3.1 and 3.3/Figures 3 and 12 report 99.13% zinc 'recovery' and 0.22 wt.% residual slag Zn at 17.5 wt.% anthracite, 1623 K and 90 min. Equation 2 actually calculates the fraction of initial-mixture Zn no longer in slag. It is not an isolated product yield: off-gas, condensate purity and a closed zinc balance are not supplied. Figures 4-5 and 8-11 retain heterogeneous residual sulfides and spatially different upper/lower slag assemblages, rather than demonstrating complete conversion to one pure phase.
Support
Source:
wang2026
Sections 2.3 and 3.1/Figure 3d report Zn extract concentrations of 960.6 mg/L for raw residue and 29.9 mg/L for the stated 17.5 wt.% anthracite treatment. The author-described TCLP assay used ground slag below 150 micrometres, acetic acid at pH 2.88 +/- 0.05, 20 mL/g, 296 +/- 1 K, 18 h, 30 rpm, 0.22-micrometre filtration and ICP-OES. Lower Zn extractability in this test does not establish zero toxicity, compliance with an independently verified regulatory limit, long-term environmental stability or recovery of other metals. The 15 wt.% anthracite arm still gave 338.4 mg/L Zn extract, retaining a less favorable outcome.
Partial
Source:
wang2026
Section 2.2 lists target temperatures 1473-1623 K, whereas the introduction and Figure 6 use 1523-1673 K. Section 3.2 assigns 10.41% Zn inventory loss to 1473 K; Figure 7a instead places 10.41% at 1323 K and 25.22% at 1473 K. These discrepancies are not silently reconciled. Equation 1 and its definition of liquid assay Ci as wt.% leave the chemical-phase normalization unclear. Reported arithmetic means and error bars lack an explicit replicate count and uncertainty definition. Detailed phase fractions and the full temperature series therefore remain qualified.
Partial
Source:
wang2026
Section 3.3 proposes desulfurization followed by 1373 K smelting and claims an iron concentrate, but the inspected methods, figures and tables do not separately document that complete sequence or product characterization. Its cited references concern other feeds. This proposal is not accepted as a second demonstrated recovery route. Suggested gas-phase reactions and oxygen-potential effects lack direct off-gas or oxygen-profile measurements here, and general statements about industrial furnaces do not deploy this particular laboratory protocol.
Sources & References
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zhang2024: Zhang, Wang, Liu, Min, Lin and Ke (2024). Research on Cu-assisted leaching process of zinc leaching residue and zinc calcine. The Chinese Journal of Process Engineering 24(5):558-565. DOI 10.12034/j.issn.1009-606X.223327. Complete eight-page original in Chinese with English abstract; Sections 2-4, Figures 1-8 and Table 1. Only the ZLR specimen is this record's feed.
https://jproeng.ipe.ac.cn/EN/Y2024/V24/I5/558 (accessed 2026-10-15) -
wang2026: Wang, Tan, Yu, Fan, Hu and Wang (2026). Assessment of zinc migration behavior and toxicity characteristics in redox smelting of zinc leaching residue. Transactions of Nonferrous Metals Society of China 36(6):1921-1933. DOI 10.1016/S1003-6326(26)67069-0. Complete 13-page original, Sections 2-4, Tables 1-2 and Figures 1-12.
https://doi.org/10.1016/S1003-6326(26)67069-0 (accessed 2026-10-15)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-15T20:24:56.474346+00:00 |
Codex GPT-6 | CREATE | Create zinc leach residue as a secondary resource with two separately scoped laboratory abiotic treatments. Preserve source-specific conditions, contradictory results and recovery limits. |
Record source: data/records/zinc-leach-residue.yaml