Q&As

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Indietro

REACH

Sostanza intermedia

Can a substance that is imported into the EU for use as a transported isolated intermediate; maintain its intermediate status where it undergoes a purification step prior to its use as an intermediate?

As described in Appendix 4 of the Guidance on Intermediates (page 35)" due to the practical nature of manufacturing processes and to the fiscal attributes of manufacturing sites, one or more steps between the manufacturing of the substance (A) and its use in the manufacturing of substance (B) may be necessary to facilitate/ensure proper chemical processing in the synthesis of substance B." Therefore, necessary purification of the intermediate, which takes place after its manufacture and before the synthesis, does not prevent it from being considered an intermediate.

Article 3(15)(c) of the REACH Regulation does not require that the manufacture of the transported isolated intermediate and its synthesis is done on sites operated by the same legal entity.

However, in order to benefit from the reduced information requirements for registration dossiers submitted under Article 18 of the REACH Regulation, the registrant must ensure that the substance is handled under strictly controlled conditions throughout its lifecycle - also if it undergoes a purification. It must also be ensured that the substance is always manufactured for and consumed in or used in the synthesis of another substance.

The Guidance on Intermediates is available on the ECHA website at: http://echa.europa.eu/guidance-documents/guidance-on-reach

Can the use of Anthracene Oil (AO) andCoal tar pitch, high temperature (CTPHT) in the manufacture of coke electrodes for the aluminium industry be regarded as the use of an intermediate?

Yes, under the conditions specified in the reasoning provided below.

Manufacturing of coke electrodes

Coal tar pitch, high temperature (CTPHT - EC number 266-028-2) and Anthracene oil (AO - EC number 292-602-7) are used in the manufacture of electrodes for applications in electrolytic processes in the aluminium industry (i.e. aluminium smelters). These substances are used specifically to manufacture the following types of electrodes:

  • Søderberg electrodes – these are first manufactured directly in the electrolytic cell and subsequently used in the same cell. 
  • pre-baked electrodes - they are manufactured in dedicated units and later used in the electrolytic cells. Electrodes manufacturing units may be located in the same site as the electrolytic cells or in another site.

In both cases, the manufacturing process of the electrodes consists of the following stages:

  1. Mixing of the raw materials (so called filler grains usually petroleum coke or calcinated coke + CTPHT and/or AO) 
  2. Shaping (to give the electrode the final shape which is required to fit it into the housing of the electrolytic cell)
  3. Baking

The outcome from the baking process is "Coke", a new substance. The new substance is manufactured from petroleum coke or calcinated coke, AO and CTPHT that contribute to its structure.

In more detail the baking process works as follows:

  1. Coke substances are carbonaceous materials obtained from coking processes such as baking at relatively high temperature. These substances are characterised by a high carbon elemental content and can display unique structures presenting a high carbon-to-hydrogen ratio. The exact composition of coke is generally complex and depends on the source used and the conditions applied for the coking. As a source of carbon, coke substances find applications in processes such as aluminium manufacturing by electrolysis. In this specific case, CTPHT and AO are themselves chemically transformed into coke during the manufacturing process of pre baked and Søderberg electrodes. These transformations involve complex chemical reactions including polycondensation and polymerisation of the constituents which CPTHT and AO consist of. These reactions begin during the baking process in a low oxygen atmosphere at temperatures of ~400 C. The transformation process into coke is completed at around ~700 C with the condensation of all polyaromatic hydrocarbons. The transformation leads to a carbonaceous material of high carbon elemental content and CTPHT and AO contribute to the structure of the coke substance intended to be manufactured. In this case, the baking process is carried out in the presence of readily available coke filler grains. The result is a homogenous coke displaying specific electrical conductivity (a required feature for the coke to be used as an electrode) and mechanical strength. In this specific case, the resulting coke would in principle not have the chemical structure that would enable its use as a source of carbon in electrolytic processes without the combined use of the AO and CPTHT as precursors and readily available coke grains.
  1. The outcome from the manufacturing process (i.e. the coke electrode) is, in this specific case, a substance under REACH and not an article as defined in Article 3(3) of REACH. The shape of the electrode is decided to fit it into the housing of the electrolytic cell, which can be different from case to case. Furthermore, during theuse of the electrodethe carbon from coke is consumed. The specific shape, surface and design given to the electrodes during their manufacture are therefore less relevant for its use in the aluminium production process than its chemical composition.

Regulatory analysis

According to Article 3(15) of REACH, an intermediate is a substance which is "manufactured for and consumed in or used for chemical processing in order to be transformed into another substance (…referred to as synthesis)".

Whenever a substance is used to achieve another function than its transformation into another substance (e.g. as an individual step in the production process of an article), it cannot be regarded as an intermediate. It is also recognised that, due to the practical nature of manufacturing processes and to the fiscal attributes of manufacturing sites, one or more steps between the manufacturing of a substance (A) and its use as an intermediate in the manufacturing of another substance (B) may be necessary to facilitate/ensure proper chemical processing in the synthesis of that other substance (B) (see Appendix IV of ECHA's Guidance on intermediates, December 2010).

In the current case, if all stages a, b and c are an integrated part of the coke manufacturing process installations, the use of AO and CTPHT may be considered the use as an intermediate.

However, whenever the mixing of AO, CTPHT and filler grains (stage a) is not carried out on the same site, this may indicate that the mixing step is not performed to facilitate/ensure proper chemical processing in the synthesis of the coke. In that case and AO and CTPHT cannot be regarded as intermediates.

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