ecoinvent Forum Archive

Hello,

i'm working on the modeling of cadmium extraction with your database.

Maybe you know that there is no cadmium mines. Cadmium is only recovered through zinc metallurgical operation (mainly hydrometallurgical route). Moreover, cadmium is considered as an impurity that have to be removed, in zinc purification process.

Also i'm wondering in what way cadmium extraction impacts are allocated, when proceeding to the impact assessment.

From my pov, as cadmium need to be separated from zinc, to reach zinc required purity, cadmium extraction impacts could be allocated to zinc metal produced. 

Is it the case in EcoInvent?

Do you think this is relevant?

If no, how should i do to model cadmium extraction as i'm working on a lare LCA about CdTe thin film photovoltaic systems.

Dear user,

Thank you for your question. In the ecoinvent database, you can find 2 activities which describe the primary production of cadmium, i.e. “cadmium production, primary” and “primary zinc production from concentrate”.

The first activity (cadmium production, primary) represents the treatment of cadmium sludges from hydrometallurgical zinc operations (modelled in the activity "primary zinc production from concentrate") and the refining of cadmium by electrolysis.  This activity represents 30% of production of refined cadmium.

The second activity is "primary zinc production from concentrate" where cadmium metal is produced as a by-product. Roughly 70 % of primary cadmium are produced in this way.

You can find this information in the meta data of the datasets (i.e. general comment, Included Activities Start/End comment, technology comment). In the meta data you will also find information on references. The activity “cadmium production, primary” for example is documented in the following report:

Classen M., Althaus H.-J., Blaser S., Doka G., Jungbluth N. and Tuchschmid M. (2009) Life Cycle Inventories of Metals. Final report ecoinvent data v2.1 No.10. Swiss Centre for Life Cycle Inventories, Dübendorf, CH.

You can find it in the report section when accessing version 2 of ecoQuery (page 474).

Regarding your second question, economic allocation is applied as a default in the ecoinvent database. You can find prices defined for the reference and by-products under the exchange properties.

I hope this answers your question.

Kind regards,

Nora Minas, Junior Data Analyst, ecoinvent Association