Phase-diagram engineered trains that split mixed-salt streams into marketable products: NaCl–Na₂SO₄ salt–glauber separation, NaCl–KCl potash recovery and high-purity salt refining — turning ZLD mixed salt from a landfill liability into by-product revenue.
Reference figures from published salt-separation and resource-recovery system data on mixed-salt and potash streams.
Evaporation concentrates the liquor; selective crystallization splits the salts; solids handling turns each fraction into a bagged product — with mother liquor looping back closed-circuit.
Mixed-salt feed → Pretreatment (filtration / pH) → Evaporator train (MEE / MVR) → Salt crystallizer (NaCl) → Centrifuge → Dryer → Salt product · Mother liquor → Cooling / freeze crystallizer (Na₂SO₄) → Centrifuge → Sulfate product · Mother liquor return (purge to dryer)
The evaporation train takes out water and crystallizes the first salt; the cooled mother liquor crystallizes the second; a controlled purge keeps impurities from accumulating — every stream leaves as product, distillate or a small handleable residue.
Aggregated from published supplier data on salt-separation, potash-recovery and mixed-salt resource systems — indicative figures for preliminary screening, not a process guarantee.
Figures aggregate published supplier specifications and project data on salt-separation and resource-recovery systems (separation evaporator builders, wastewater evaporation contractors, potash-recovery technology providers). Purity and capacity values are duty-specific — your feed’s salt composition and phase behavior govern what is achievable; send a full water analysis for a case-specific assessment.
The same separation logic — concentrate, crystallize selectively, close the liquor loop — dressed three ways by feed and product target.
Anonymized configurations reconstructed from published supplier project data.
Engineering guides on separation route selection, salt–glauber systems, salt refining and potash recovery.
The crystallization bodies, equipment modules and solution pages this system is built from.
This page aggregates published supplier specifications and project data (separation-evaporator builders, wastewater evaporation contractors, potash-recovery technology providers) into an engineering screening view. All names are withheld; configurations are described generically. Purity and capacity figures are duty-specific published values, not universal guarantees — separation performance is governed by your feed’s salt composition and phase behavior, and must be confirmed against a full water analysis.
Recurring questions from engineers assessing mixed-salt resource recovery.
Sequential selective crystallization suits systems of up to about three salts whose solubility behavior is distinctly different — NaCl–Na₂SO₄ and NaCl–KCl are the two classic pairs. The first screening step is a full salt-composition analysis laid on the phase diagram: if the salts’ solubility curves diverge across the operating temperature range, a separation route exists.
By ternary phase-diagram analysis with the lever rule — the published design basis for mixed Na₂SO₄/NaCl systems. The diagram fixes which salt crystallizes first as water is removed, at what concentration the second salt drops out, and the recoverable yield of each fraction; hardware is sized only after that split is calculated.
Evaporative separation handles feeds from roughly 0.5% to 30% salinity. Below ~0.5%, a membrane pre-concentration stage (single membranes rated up to 0.45 m³/h) lifts the salinity to where thermal separation is economic. The comparison against the alternatives matters too: evaporation crystallization consumes almost no chemicals and carries no resin or exchange-membrane consumables.
Published K–Na separation duty reports NaCl at ≥95% and KCl at ≥85%; mixed-salt separation reports separated salts at national by-product salt standard — the grade that allows direct resource use rather than disposal. On potash recovery duties, >99% K₂SO₄ (FCO grade) white crystals are in commercial operation. Marketability still depends on your local by-product regulations.
Both run on the same flowsheet — published systems offer either configuration. MVR variants report energy savings above 60% versus conventional evaporation on comparable salt duty, at the cost of compressor capital and a power supply; MEE trades energy for simplicity where live steam is cheap. The choice is an energy-price calculation, not a process constraint.
Mother liquor returns closed-circuit to the evaporator train, with a controlled purge keeping impurities bounded — a mother-liquor drying unit can recover the balance as solid. Desalted residues need not be landfilled: in the published potash-from-ash system, the depleted residue goes to brick making, making the recovery loop zero-waste and offsetting ZLD operating cost.
Representative configuration of a 40 t/h (2 x 20 t/h) TVC-driven four-effect evaporation and crystallization train in Southwest China separating ammonium sulfate from magnesium sulfate with ammonia removal, in 2205
Representative configuration of a 1,200 t/d silica-production wastewater zero-liquid-discharge plant in East China: 50 t/h double-effect evaporation with salt separation in 2205 duplex stainless construction, integrating 200,000 Nm³/h waste-heat recovery.
Send the full water analysis — salt composition, concentration range, daily volume and any purity targets. We will return a phase-diagram separation assessment with the crystallization route and an indicative equipment configuration — not a brochure.
Send your feed characterization (TDS, COD, main salts, viscosity), throughput and product targets — we respond with a preliminary process route within two business days.
