Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
  • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
  • C25C3/12—Anodes
  • C25C3/125—Anodes based on carbon

Definitions

• the present invention relates to 'the' socalled continuous electrodes, which are baked in the electric furnace in which they are used and the object of the invention is to provide an improved electrode mass from which an electrode is obtained hav ng first class mechanical and electric qualit1es.
• the usual carbon electrodes for electrothermic use are, as'is known, made by mixing anthracite, previously heated to a red heat, cinders and other carbon materials with a binder, comprising pitch with some oil, or tar and pitch, to form a mass-which is pressed or tamped into moulds.
• the electrodes thus formed are then baked in special baking furnaces where they are slowly heated until the binder is ooked, usually to least possible amount of volatile constituents. The less volatile constituents there are contained in the electrode mass, the
• the moulding of the electrode must be effected by means of high pressures or powerful blows whereby the particles of the 65 as it is termed be able to take pressing?" mass are pressed together and the air con tained is driven out.
• tamping one has been able to make good electrodes.
• the process then consists in subjecting the electrode mass to a tamping b means of a ram-like tamping apparatus. 0th with regard to the transportation and the baking of the raw elec trodes and to. make the mechanical treatment of the mass efiective the electrode mass must have a definite consistency. It must I and take tamping.
• Electrodes stand less current density than first class electrodes and may in many cases lead to breakage, the electrodes not being strong enou h to stand the strains to which they will e subjected.
• This behaviour is especially noticeable in the production of se fbaking electrodes which are provided with an ironor metal armature.
• Such electrodes generall consist of an iron mantle with inwardly irected' radial longitudinal ribs and this armature encloses the electrode mass and determines its form. In the lower part of the armature facing the furnace the electrode'mass will. be ready baked, in the upper part it is entirely raw.
• the ribs transmit the current from the electrode holder to the baked part of the electrode and hold this tight for which reason they are provided with projections or the likewhich prevent the hard baked electrode from moving relatively to the ribs.
• Such a continuous electrode is generally4 to 7 meters long.
• the resulting hard non-electric mass is fixed the armature is subjected to a strainwhich may result in a division of the electrode into pieces whose length varies with the electrode diameter and temperature conditions.
• Amount of binder 27.5%, 28%, 28.5%, 29%, 30 32%.
• the absolute percentage at which the mass ceases to be tampable depends on the amount of fine particles in the electrode mass and on the nature of the fines, and can therefore not be determined beforehand.
• the turning point of the curve was found to be at 27.5% binder. This is of course only the case in a mixture of definite fines with a definite binder. If the quality or fineness of the fines are altered the turning point will become displaced. Under all circumloo binders. The coarse particles require very little I binder to .become moistened. The pieces are in the mass completely surrounded by fines on all sides and the consistency of the fines determines that of the mass.
• the iron mantle moves slowly downwards together with the electrode mass towards the crater of the furnace.
• the temperature of the mass rising slowly from. about 60 C. to a bright red heat at the point of the electrode.
• the first distillation of the most volatile constituents of the mass begins and these escape in the form of vapor.
• the binders are transformed to highmolecular carbon compounds which are slowly transformed to a gradually harder coke.
• the porosity of the electrode is increased.
• the raw mass durin the tamping still contains some air, but uring the storing in the electrode a part of the air escapes and the porosity sinks to about 5%. In the completely baked electrode it is about 15 to 20%.
• An electrode mass for use in forming continuous electrodes containing an excess of binder in proportions suiiiciently high to cause the mass in warm condition to settle in the electrode.
• An electrode mass for use in forming continuous electrodes in which. the proportion of binder content is sufficiently high to render the mass elastic and non-tampable.
• An electrode mass for use in forming continuous electrodes in which the proportion of binder content is sufiiciently high to prevent reduction of the total volume of the mass under a tamping action.
• An electrode mass for use in forming continuous electrodes in which the proportion of binder content is sufficiently high to render the mass liquid.
• An electrode mass for use in forming continuous electrodes in which the binder content forms at least 14% of the mass.
• An electric furnace electrode of the kind which is baked during its use in any electric furnace characterized by a baked portion at the operating end and by soft electrodepaste at the feeding end, said paste being of such consistency as automatically to exert sufiicient pressure by its own weight to assure such compa tness of the electrode materials throughout the baked portion of the electrodes as to afford physical and electrical characteristics of a pre-baked electrode.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Discharge Heating (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=19909955

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Country Status (4)

Cited By (5)

Families Citing this family (1)

• 0
  • NL NL15605D patent/NL15605C/xx active
• 1924
  • 1924-07-12 DE DED45822D patent/DE443907C/de not_active Expired
  • 1924-07-22 FR FR584594D patent/FR584594A/fr not_active Expired
  • 1924-07-22 US US727597A patent/US1670052A/en not_active Expired - Lifetime

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