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PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
Definition statement
This subclass covers:

Electrolytic production or recovery (electrowinning) of metals and alloys from solutions or melts.

Electrorefining of metals and alloys in solutions or melts.

Constructional parts, cells or assemblies of cells for the electrolytic production, recovery or refining of metals or alloys.

Servicing or operating of cells for the electrolytic production, recovery or refining of metals or alloys.

Relationship between large subject matter areas
  • Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process provided for in class C25 are classified in group C23F 17/00
  • Compounds of particular interest are also classified in the relevant classes, C01 (inorganic chemistry), C07 (organic chemistry) and C08 (organic macromolecular compounds).
  • The electrolytic or electrophoretic purification of materials is classified according to the nature of the liquid in the relevant places, e.g. A01K 63/00, C02F 1/46, C25B 15/08, C25D 21/16, C25F 7/02
  • The electrolytic deposition of coatings (electroplating), the electrophoretic production of coatings and electroforming is classified in C25D.
  • Production and refining of metals by non-electrolytic processes is classified in C22B, C21B, C21C. An electrothermal treatment (C22B 4/00) does not involve an electrolytic process.
  • Alloys as such, prepared by electrolytic methods are classified in C22C.
References relevant to classification in this subgroup
This subclass does not cover:

Removing metallic impurities from waste water or sewage by electrolytic methods

Inhibiting corrosion of metals by anodic or cathodic protection

Single crystal growth

Informative references
Attention is drawn to the following places, which may be of interest for search:

Catalysts comprising metals, metal oxides or hydroxides

Processes for preparing catalysts

Refining molten metal during a continuous casting process

General processes of refining metals

Composition of alloys

Multistep processes for surface treatment of metallic material

Electrodes, membranes for fuel cells

Special rules of classification within this subclass

Classify each metal mentioned in the document, if too many are mentioned, then classify the examples and for the rest of the metals use C25C 1/00 or C25C 3/00, respectively.

Electrolytic production, recovery or refining of metals by electrolysis of solutions (C25C 5/00 takes precedence)
Special rules of classification within this group

Classify also in C25C 5/02, when applicable.

Electrolytic production, recovery or refining of metals by electrolysis of melts (C25C 5/00 takes precedence)
Special rules of classification within this subgroup

Classify also in C25C 5/04, when applicable.

Glossary of terms
In this group, the following terms (or expressions) are used with the meaning indicated:

Melt

molten salt or ionic liquid or fused bath

Cell construction, e.g. bottoms, walls, cathodes
References relevant to classification in this subgroup
This subgroup does not cover:

Constructional parts, or assemblies thereof, of cells; servicing or operating of cells for the production of alloys or metals other than aluminium

Anodes
Informative references
Attention is drawn to the following places, which may be of interest for search:

Electrodes used in cells for the electrolysis of melts, other than aluminium production

{based on carbon}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Carbon masses

Electrodes used in cells for the electrolysis of melts, other than aluminium production

Electrodes used for heating by electrical discharge, electrodes mainly consisting of carbon, self-baking type (e.g. Söderberg anodes)

H01B7/09

Heating by electrical discharge, electrodes mainly consisting of carbon

Glossary of terms
In this subgroup, the following terms (or expressions) are used with the meaning indicated:

Söderberg anode

An electrode used in metallurgy, which continuously forms in an electrical furnace when a mixture of coke and coal-tar pitch is added to a heated steel casing and is baked as it passes through. It emerges into the furnace where it is continuously consumed.

Automatic control or regulation of cells (controlling or regulating in general G05)
Informative references
Attention is drawn to the following places, which may be of interest for search:

Controlling or regulating in general

of titanium, zirconium, hafnium, tantalum or vanadium
Definition statement
This subgroup covers:

Electrolytic production of the metal (titanium, hafnium, tantalum, vanadium) by the direct reduction of the metal ion at the electrode.

Reduction of the metal oxide by another metal (usually calcium) which is itself electrolytically reduced from the electrolyte (usually calcium chloride), although the reduction step of the metal ions is chemical rather than electrolytic.

Relationship between large subject matter areas

Documents involving the latter reaction should also be considered by a classifier in C22B 34/00.

Special rules of classification within this subgroup

Classification should also be made in C25C 5/04, when applicable.

of titanium
Definition statement
This subgroup covers:

Electrolytic production of titanium by the direct reduction of the metal ion at the electrode.

Reduction of titanium oxide by another metal (usually calcium) which is itself electrolytically reduced from the electrolyte (usually calcium chloride), although the reduction step of the titanium ions is chemical rather than electrolytic.

Relationship between large subject matter areas

Documents involving the latter reaction should also be considered by a classifier in C22B 34/12.

Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells (for the production of aluminium C25C 3/06 to C25C 3/22)
References relevant to classification in this group
This group does not cover:

Constructional parts, or assemblies thereof, of cells; servicing or operating of cells for the production of aluminium

{of cells comprising at least a movable electrode (C25C 7/002, C25C 7/02 to C25C 7/06 take precedence)}
Definition statement
This subgroup covers:

Movable electrodes, be it electrodes that move in space or electrodes that move around an axis, such as rotary electrodes.

Diaphragms; Spacing elements
Informative references
Attention is drawn to the following places, which may be of interest for search:

Diaphragms used in the electrolytic or electrophoretic production of compounds or non-metals

Membranes for fuel cells

Synonyms and Keywords

In patent documents the following expressions/words "diaphragm" and "membrane" are used as synonyms

Operating or servicing
Definition statement
This subgroup covers:

Operating or servicing of cells, when generally applied to a cell or in a process of C25C.

Informative references
Attention is drawn to the following places, which may be of interest for search:

Controlling or regulating in general

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Last Modified: 10/11/2013