Potassium permanganate from MnO2 ore by KOH roasting and electrolysis (1250 kg/h, concept)

Technical-grade KMnO4 from manganese ore: KOH roasting with air to potassium manganate, leaching, electrolytic oxidation in divided cells, crystallisation and drying, with the KOH recycled by evaporation. Concept stage, assumed basis, preliminary gate-to-gate inventory.

Calculation maturity: not assessedDesign maturity: Concept (research)Not independently reviewedInorganic chemicalsReport a problem with this process
Research outputNot engineering advice and not an approved design: do not use it for construction, operation or safety decisions. What this means

Dried, ground MnO2 ore is roasted with concentrated KOH (recycled from the evaporator plus 50 wt% make-up) and air in an indirectly gas-fired kiln at about 523 K, giving a potassium manganate cake. The cake is leached with recycled mother liquor at 333 K; lime precipitates the dissolved silicate, and the residue (unreacted MnO2, gangue, calcium silicate) is filtered and washed with the evaporator condensate. The manganate liquor is oxidised to permanganate in divided cells (cation-exchange membrane, 2.5 V, 1000 A/m2); hydrogen leaves the cathodes. KMnO4 crystallises on cooling to 303 K, is centrifuged and steam-dried. Most of the mother liquor returns to the leach; a share is concentrated to 50 wt% KOH for the roaster and 3 % is purged. Overall 2 MnO2 + 2 KOH + O2 -> 2 KMnO4 + H2.

All flows are concept estimates from an independent sequential balance (scripts/kmno4_balance.py) on assumed design parameters (roaster conversion, current efficiency, cell voltage, mother-liquor composition, purge), anchored where possible to patent ranges (US 5660712, US 5011672). No electrolyte speciation or solid-liquid equilibrium is calculated. See DESIGN.md for every assumption and gated step.

Capacity
1250 kg/h technical-grade KMnO4, 10 000 t/a (ASSUMED normalisation basis)
Operation
8,000 h/a
Location
generic (not chosen)
Engineering gates
Concept and feasibility (no results yet)
Maintainers
Artur Schweidtmann
Design basis and assumptions (7)
  • ASSUMED MnO2 conversion to K2MnO4 0.90 in the roaster at 523 K, KOH/MnO2 2.5 mol/mol (US 5011672 optimum), air O2 2.0 x stoichiometric, 25 % of the gangue silica dissolved (D-004).
  • ASSUMED leach at 333 K with recycled mother liquor; lime 1.10 x the dissolved silicate; residue cake 0.6 kg liquid/kg solids, displacement wash recovering 90 % of the solutes (D-005).
  • ASSUMED cell feed 6.0 wt% K2MnO4; 90 % conversion per pass; current efficiency 0.85; 2.5 V per cell; 1000 A/m2; 333 K (D-006).
  • Mother liquor 1.5 wt% KMnO4 and 13 wt% KOH at 303 K, inside the likely ranges of US 5660712 (15-20 g/l KMnO4, 125-175 g/l KOH); centrifuge cake 6 wt% liquid; product 0.2 wt% moisture (D-007).
  • ASSUMED mother liquor split: 3 % purge; the evaporator share set by the roaster KOH demand, concentrate 50 wt% KOH (D-008).
  • ASSUMED duties from a lumped enthalpy balance (scripts/kmno4_balance.py): constant heat capacities, roaster losses 15 %, double-effect evaporator economy 1.8, dryer efficiency 0.65, rectifier efficiency 0.97, auxiliary power 150 kWh/t (D-009).
  • No electrolyte thermodynamics: liquors are carried as neutral molecules; no property package covers the streams (D-010).

From process/design-basis.yaml.

Engineering model

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The interactive model (drawings, streams, 3D) is made for larger screens.

Snapshot of c3ab348, cheme-as-code 1.6.0.

What goes in and out

In

  • Manganese dioxideFeedstockfeed:ORE: manganese ore (MnO2 concentrate), dried and ground, 0.787 kg/kg
  • Potassium hydroxideFeedstockfeed:KOH: potassium hydroxide make-up, 50 wt% solution, counted by mass of the solution
  • Calcium hydroxideFeedstockfeed:LIME: hydrated lime
  • WaterFeedstockDemineralised process water to the leach
  • AirFeedstockRoaster oxidant

Out

  • Potassium permanganateMain productPotassium permanganate, technical grade, to packing
  • WastewaterWasteMother-liquor purge (KOH, manganate, permanganate) to effluent treatment, ~0.70 kg/kg
  • HydrogenEmissionCathode hydrogen vented, ~8 g/kg; recovery as fuel is an open option

Utilities: Electricity (DC for the cells through rectifiers (0.55 kWh/kg AC) and auxiliaries), Steam (LP steam 450 kPa(a): KOH evaporator, leach heating, dryer (counted as heat, kWh)), Cooling water (25/35 C (ASSUMED))

Show in the process graph

Reactions

IdAs writtenReactionOther processes
ELEC2 K2MnO4 + 2 H2O → 2 KMnO4 + 2 KOH + H2 · Anodic oxidation of manganate to permanganate (overall cell reaction)2K2MnO4+2H2O2KMnO4+2KOH+H2
LIMEK2SiO3 + Ca(OH)2(s) → CaSiO3(s) + 2 KOH · Silicate removal with lime (causticising the silicate back to KOH)K2SiO3+CaH2O2CaSiO3+2KOH
OX2 MnO2(s) + 4 KOH + O2 → 2 K2MnO4 + 2 H2O(g) · Oxidation of MnO2 to potassium manganate in KOH with air (roaster)2MnO2+4KOH+O22K2MnO4+2H2O
REDKM4 KMnO4 + 4 KOH → 4 K2MnO4 + O2 + 2 H2O(g) · Reversion of recycled permanganate to manganate in the hot KOH melt4KMnO4+4KOH4K2MnO4+O2+2H2O
SILSiO2(s) + 2 KOH → K2SiO3 + H2O(g) · Attack of silica gangue by KOH (alkali loss)SiO2+2KOHK2SiO3+H2O
WATER_SPLIT2 H2O → 2 H2 + O2 · Anodic oxygen evolution (current-efficiency loss; net water electrolysis)2H2O2H2+O21 other process

Each reaction's page has the conversion, heat of reaction, catalyst and sources this process states, next to those of other processes with the same reaction. All reactions

Life cycle assessment

–kg CO2-eqPreliminarypartial, 10 data gaps

Climate change per 1 kg Potassium permanganate (technical grade), cradle-to-gate

No factors. No contribution is characterised, so no factor stands behind any number.

Main contributors
    Method and data
    Goal
    Preliminary foreground (gate-to-gate) life cycle inventory of technical-grade potassium permanganate from manganese ore by KOH roasting and electrolytic oxidation at the concept stage: which raw materials, utilities, emissions and wastes the balanced flowsheet implies per kg of product, ready to be linked to background datasets later. Flows are concept estimates on assumed design parameters (DESIGN.md D-004 to D-009).
    Functional unit
    1 kg Potassium permanganate (technical grade) (1 kg potassium permanganate)
    Boundary
    cradle-to-gate
    Allocation
    none
    Characterisation
    Factors kept with the process · GWP100
    Data quality
    No factors
    Result
    partial screening carbon footprint · 10 data gaps
    ScenarioClimate change (kg CO2-eq)
    baselineno total (data gaps)

    Inventory per 1 kg Potassium permanganate (technical grade) (20 flows)

    FlowPhaseDirectionQuantityUnitProvenance
    Manganese ore (MnO2 concentrate) dried and groundoperationinput0.7874kgassumed
    Potassium hydroxide make-up (50 wt% solution)operationinput0.9197kgassumed
    Roaster airoperationinput0.8769kgassumed
    Hydrated limeoperationinput0.03204kgassumed
    Process wateroperationinput1.313kgassumed
    Fired heat (natural gas, indirect firing of the roaster)operationinput0.991kWhassumed
    LP steam 450 kPa(a) (condensate returned)operationinput1.722kWhassumed
    Electric power (AC, grid)operationinput0.6958kWhassumed
    Potassium permanganate (technical grade) to packingoperationoutput1kgassumed
    Washed leach residue to disposaloperationoutput0.3902kgassumed
    Mother-liquor purge to effluent treatmentoperationoutput0.7035kgassumed
    Roaster off-gas to atmosphere (after the dust scrubber)operationoutput1.767kgassumed
    Cathode hydrogen to atmosphere (diluted vent)operationoutput0.007968kgassumed
    Anode oxygen to atmosphereoperationoutput0.00948kgassumed
    Dryer exhaust vapour to atmosphereoperationoutput0.05155kgassumed
    Cooling water returnoperationoutput2.076kWhassumed
    H2 to the environmentoperationoutput0.007968kgassumed
    H2O to the environmentoperationoutput1.04kgassumed
    N2 to the environmentoperationoutput0.6735kgassumed
    O2 to the environmentoperationoutput0.1143kgassumed

    Computed by ChemE-as-Code from lca/README.md, lca/dataset.yaml, lca/factors.yaml, lca/gaps.csv, lca/inventory.csv, lca/lca.yaml, lca/mappings.yaml, lca/results.csv, lca/results.md, lca/uncertainty.csv.

    In the open LCI database (cheme-as-code-atlas-preview-c3ab348) as Potassium permanganate (technical grade) to packing Preliminary.

    Download it for Brightway, openLCA and other tools.

    In the LCI database: system model, datasets and KPIs against the benchmarks

    In the LCI database

    Status
    Preliminary 4 unmapped exchanges. Some exchanges have no background mapping yet: they are exported unlinked and count no burden, so the inventory is incomplete.
    System model
    attributional, cut-off (methodology 1.1.0)
    Allocation
    none (single-output, from study) · product:KMNO4 100 %
    Allocation findings
    none
    Change report
    Not available: this build has no change report against an earlier release.
    Dataset pages
    Potassium permanganate (technical grade) to packing Preliminary

    KPI benchmark positions: not available (no benchmarked KPI for this process's datasets).

    Maturity and review

    Design maturity Concept (claimed): An idea or first flowsheet; numbers are rough. Concept BFD/PFD with closed mass, component and element balances (cheme validate, cheme process streams: 5 blocks, 10 steps, reactive balances by extents) and a closed Faraday, charge and energy balance of the cells (cheme process cell). All flows and compositions are specified values of an independent balance (scripts/kmno4_balance.py) on assumed design parameters; the current efficiency (0.85) has no open source and the cell voltage (2.5 V) is only bracketed by a patent range. No electrolyte speciation and no multi-solute crystalliser (the core crystalliser models one solute); no property package covers the liquors, melts and solids, so the duties are a lumped script estimate. The gate-to-gate LCI is preliminary, with every background unmapped. `cheme maturity` evaluates the calculation maturity to none and warns that the concept claim exceeds the evidence (cheme.maturity-claim-exceeds): concept is kept only because the manifest schema has no lower level; read it as "below concept: sourced screening on assumed parameters". Independently reviewed once (reviews/2026-10-28-pfd-lci-review.md); not signed off.

    Calculation maturity, from the checked evidenceNot assessed

    The process has no maturity report (cheme maturity, checks/maturity.json), so no calculation maturity is established.

    No level shownThe design maturity (Concept) is the manifest's claim, not evidence. A level appears here once the process's repository holds a current report from cheme maturity --write.

    Artifact completeness

    Which deliverables exist. They never raise a calculation maturity level: a drawing from unchecked numbers is still unchecked.

    Not reported without a maturity report.

    Independent review

    Not independently reviewed

    No independent engineering review yet. Automated checks passing is not a review.

    Set by people only. Reaching a calculation maturity level or passing automated checks is not an independent review or an approval.

    Where the evidence comes from
    Report
    processes/potassium-permanganate-1/checks/maturity.json (not in the library)
    Design basis
    process/design-basis.yaml
    Method
    How ChemE-as-Code checks the levels (requirement by requirement)

    Open items

    0 open items · 0 closed

    New action itemNew engineering holdNew technical queryNew design changeAll issues

    Sources

    Engineering project
    Potassium permanganate · cheme-as-code>=0.8
    Library version
    c3ab348 (process last changed in c3ab348)
    Drawings rendered by
    cheme 1.6.0 (pyDEXPI 2.1.0)
    Data
    Catalog record (JSON) · CC-BY-4.0
    Files
    View the files on GitHub · change history and authors

    References

    How to cite

    For the data, cite the Process Atlas paper; for the platform that builds and checks it, the ChemE-as-Code paper.

    Schweidtmann, A. M. & Weber, J. M. (2026, in preparation). Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title).

    For this process: "Potassium permanganate from MnO2 ore by KOH roasting and electrolysis (1250 kg/h, concept)", ChemE-as-Code process library, version c3ab348.

    BibTeX
    @unpublished{schweidtmann_process_atlas,
  author = {Schweidtmann, Artur M. and Weber, Jana M.},
  title = {{Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title)}},
  year = {2026},
  url = {https://atlas.cheme-as-code.org},
  note = {in preparation}
}

    Schweidtmann, A. M. (2026, in preparation). ChemE-as-Code: An Open-Source Platform for AI-Accelerated Chemical Process Engineering (working title).

    BibTeX
    @unpublished{schweidtmann_cheme_as_code,
  author = {Schweidtmann, Artur M.},
  title = {{ChemE-as-Code: An Open-Source Platform for AI-Accelerated Chemical Process Engineering (working title)}},
  year = {2026},
  url = {https://cheme-as-code.org},
  note = {in preparation}
}