Common dysprosium salts and compounds: solubility and recovery
Dysprosium in industrial and mining process water may occur as dissolved Dy(III) or in suspended solids. Its behavior depends on the salt present and the chemistry of the water. The table below distinguishes soluble process salts from minerals and solids that may form during treatment. Neodymium, Nd(III), is included where the cited studies provide useful comparisons; its behavior should not be assumed to be identical to dysprosium.
Solubility of dysprosium salts and compounds
| Compound and formula | Reported solubility behavior and caveat | Where encountered |
|---|---|---|
| Dysprosium sulfate, Dy2(SO4)3, including hydrates | Solubility varies with temperature, pH, sulfate concentration and other dissolved salts. Measurements for Dy and Nd sulfates cover pH 2–7 and 25–80 °C, including sodium- and ammonium-sulfate mixtures; a single value cannot represent all streams [1]. Hydrate form also matters when comparing solid salts [5]. | Sulfate-rich leach solutions and process salts; possible solid phases in concentrated streams. |
| Dysprosium chloride, DyCl3 | Generally soluble as a process salt; dissolved Dy(III) can subsequently complex or precipitate as water chemistry changes. | Chloride-based process solutions and reagents. |
| Dysprosium nitrate, Dy(NO3)3 | Generally soluble as a process salt. This does not establish the solubility of other dysprosium compounds formed downstream. | Nitric-acid process solutions and reagents. |
| Dysprosium carbonate, Dy2(CO3)3, and basic carbonates | Carbonate-bearing solids may have low solubility, but dissolved carbonate complexes and alternative solid phases complicate prediction. Nd carbonate studies also show double-salt precipitation under particular solution conditions [4]. | Carbonate-rich waters, neutralization solids and precipitation processes; not necessarily the same phases as natural carbonate minerals. |
| Dysprosium hydroxide, Dy(OH)3 | Precipitation becomes more favorable as pH rises; dissolved complexes and competing ions can shift the observed removal point. | Alkaline neutralization and treatment precipitates. |
| Dysprosium oxalate, Dy2(C2O4)3 | Low-solubility precipitate under suitable conditions; acid concentration, competing metals and oxalate dose affect crystallization and product composition [3]. | Oxalic-acid recovery steps and mixed rare-earth concentrates. |
| Dysprosium phosphate, DyPO4 | Low-solubility phase where phosphate is available; the amount formed depends on solution chemistry and competing phosphate reactions. | Phosphate-bearing waters, treatment solids and distinct naturally occurring phosphate minerals. |
| Dysprosium fluoride, DyF3 | Low-solubility phase under suitable fluoride conditions; fluoride complexation and the activities of dissolved species also affect behavior. | Fluoride-bearing process solutions and precipitates; distinct from natural fluoride minerals. |
Interpreting results from actual streams
A salt formula does not, by itself, identify the dissolved species or the solid present in a plant stream. pH influences hydrolysis and precipitation, while temperature, ionic strength and sulfate or carbonate concentrations affect activities, complexation and solid-phase equilibria [1, 4, 5]. Hydrates can produce different reported solubility results; concentrations reported for a pure salt in water should not be transferred uncritically to a mixed liquor. Mine-drainage treatment wastes can contain rare earths associated with several solid phases, rather than a single identifiable dysprosium compound [2].
Treatment and recovery options
Neutralization can transfer dissolved rare earths into solids, including hydroxide- or carbonate-bearing precipitates. Iron or aluminium precipitation may co-remove them; freshly formed Fe, Al or Mn oxides can also sorb dissolved rare earths [2]. These routes generate residuals and may collect several elements together rather than yield a recoverable dysprosium product.
Cation or chelating ion exchange can capture dissolved rare earths, followed by elution to produce a smaller, more concentrated stream [3, 6]. Competing ions, solution chemistry and regeneration affect the resulting separation. Staged precipitation and oxalate crystallization can then be evaluated for a mixed rare-earth concentrate; reported recovery depends on the element mix and operating conditions [3]. Neither precipitation nor ion exchange guarantees selective single-element dysprosium recovery.
Nanofiltration or reverse osmosis may be considered to concentrate a suitable stream where osmotic pressure, scaling and fouling permit. They are not inherently selective methods for recovering dysprosium from other rare earths. Representative-stream testing is needed to assess separation, residual water quality and management of spent regenerants, concentrates and precipitated solids.
Discuss a dysprosium treatment or recovery challenge
For an enquiry about a dysprosium-bearing water or process stream, contact Lenntech with the available information about its composition and treatment objective.
Discuss a water-treatment challenge
Last reviewed: 8 November 2026 by Lenntech.
Sources and further reading
- [1] Cunningham et al. (2024), measured neodymium and dysprosium sulfate solubility, Hydrometallurgy 224. DOI: 10.1016/j.hydromet.2023.106253. Read study.
- [2] Hedin et al. (2024), rare-earth associations in mine drainage treatment wastes, USGS. Read publication.
- [3] Crespo et al. (2026), ion exchange followed by oxalic-acid precipitation from acid mine water. Read study.
- [4] Yang et al. (2019), neodymium carbonate solution behavior and double-salt precipitation, ACS Omega. Read study.
- [5] IUPAC Solubility Data Series, Dysprosium. View data series.
- [6] Lenntech, Ion Exchange.