REACH - Applications for authorisation AFA066-01 Chromium Trioxide

Overview

Public consultation on alternatives

Reference: AFA066-01

Applicant: Vertik-al ltd (7 companies – see names on application documents)    

Application Type: Initial application

Substance Name: Chromium Trioxide

• EC Number: 215-607-8       
• CAS Number: 1333-82-0

Annex 14 Entry number: 16

Proposed Use: Pre-treatment conversion coating of aluminium for the construction industry by spray and dip process.

Broad Information on Use Applied for (Conditions of Use and Function): 

The consortium operates powder coating facilities for aluminium mainly for the architectural industry, they operate pre-treatment lines based on Chromium trioxide (Chromic acid) by the chromium phosphate conversion method (green chromate). The Chromium trioxide is used as a conversion layer coating for aluminium to provide a suitable base for powder coating of architectural parts. The parts require good adhesion of the paint coating and corrosion resistance in all environments.

The aluminium is oxidised with the loss of electrons, chromic acid is reduced with the gain of electrons, with the addition of phosphoric acid a further conversion takes place. The conversion coating is characterised by chromic oxide at the aluminium surface and chromic phosphate forming a layer on top. These reactions are dependent on the concentrations, free Fluoride and the pH. The chromium on the surface of the aluminium after conversion is in its trivalent transition state so that Chromium Trioxide does not appear in the downstream uses. The chromium provides adhesion of the powder paint to the aluminium, corrosion resistance and is self-healing so that damage to the paint does not result in corrosion. The consortium companies operate pre-treatment lines by spray or immersion plant for extrusions, fabrications and panel work.

List of Descriptors:  

• Sector of end Use (SU): 3 (Industrial end use, pre-treatment)
• Process category (PROC): 0, 1, 2, 3, 8a, 8b, 15
• Environmental release category (ERC): ERC7

Annual Tonnage Used: 10 - 100 tonnes per annum (all sites combined)

Review Period Requested: 12 years

How to submit comments

Provide some basic information on possible alternative(s) in the online survey below but more detailed information should be provided in document(s) prepared using the commenting templates in the related section below. A “public version” should always be completed and will be published after the consultation has closed. If you want to include confidential information in your submission, please additionally complete a “confidential version” and submit both versions as attachments.

The consultation lasts for 8 weeks (unless otherwise specified) and closes at 23:59 London time (BST).