Substance description/characteristics
The substance Cadmium, dross is a UVCB (origin: inorganic)
Public name: Cadmium dross
| EC number: | 273-707-7 |
| EC name: | Cadmium, dross |
| CAS number (EC inventory): | 69011-69-4 |
| Description: | The scum is isolated, from the molten metallic bath, by mechanical separation (rattling). The separated material is poured into small containers near the furnace or the casting line and allowed to cool down. Further transfer of the Cadmium-dross to enclosed or covered buildings through especially designed transfer units, i.e. trucks, big-bags or containers, in accordance with legislation. Cadmium-dross is used to produce Cadmium metal and Cadmium compounds. |
| Molecular formula: | n.a. |
| Molecular weight range: | n.a. |
| Physical state: | Solid (massive) at 20°C, 1013 hPa |
2. Source, process and conclusion
| Source | Cadmium cathodes |
| Process |
When refining, melting and casting cadmium and cadmium alloys, a scum is formed on the surface of the melt, consisting of cadmium, cadmium oxide and small amounts of the alloying elements, their oxides and possibly fluxing agents. The scum is extracted/isolated from the surface of the metallic bath by mechanical separation (rattling). The separated material is poured into small containers near the furnace or the casting line and allowed to cool down. The furnace(s) are placed under negative pressure and the exhaust gases are filtered before release to the stack; the dust collected in the bag-house filters has a very similar composition as the Intermediate EC 273-707-7. So, the basic reaction to form the intermediate is the atmospheric oxidation of metallic cadmium to cadmium oxide. The molten metallic cadmium phase or alloyed cadmium (EC 231-152-8) are cast and delivered to downstream users. The Intermediate EC 273-707-7 is further transferred to enclosed storage zones or silos through especially designed transfer units: forklift, containers and/or conveyors, pneumatic transport. It is unloaded from transport trucks, trains, ADR-big-bags or containers and transferred to storage zones or silo’s through specially designed transfer units. It is optionally blended with other cadmium containing primary or secondary materials and fed to the treatment unit if not temporarily stored. The mixture can be fed to: => Pyro-process: rotary furnace, induction furnace, ISF, etc. for production of cadmium => Hydro-process: chemical hydrometallurgical reactors for further synthesis reactions of another cadmium compound, i.e. cadmium chloride EC 233-296-7 It is typically used in the production of cadmium or cadmium compounds. |
| Conclusion | Scum formed on the surface of molten cadmium isolated to be further used for the production of cadmium metal and cadmium compounds. Cadmium dross is further processed to excrat Cd or Cd compounds. |
3. Composition of the substance
The Cadmium, dross boundary composition is detailed here below.
Elemental composition - boundary:
| Core | min (% w/w) | max (% w/w) | Typical (%w/w) |
| Cd | 65 | 90 | 80 |
| Na | 2 | 15 | 1.92 |
| Zn | 0.1 | 2 | 0.37 |
Mineralogical composition - boundary:
|
Core |
min (% w/w) | max (% w/w) | Typical (%w/w) |
| Cd | 36.97 | 51.19 | 45.50 |
| CdO | 22.28 | 30.84 | 27.42 |
| Na2CdO2 | 14.45 | 20.01 | 17.78 |
| Na2CO3 | 2 | 15 | 8.84 |
| ZnO | 0.12 | 2.49 | 0.46 |
4. Classification revised 2024
| The classification is always based on the worst case. For Cadmium, dross, this corresponds to: | |
|
Acute toxicity - oral |
Acute tox oral 4 |
| Acute toxicity - inhalation | Acute tox inhalation 2 |
| Germ cell mutagenicity | Muta 2 |
| Carcinogenicity | Carc 1B |
| Reprotoxicity | Repro 2 |
| Specific target organ toxicity - repeated: | STOT RE 1 |
| Hazards to the aquatic environment (acute/short-term): | Aquatic Acute 1 |
| Hazards to the aquatic environment (long-term): | Aquatic Chronic 1 |