CS212770B2 - Graphite agglomerate and method of producing same - Google Patents

Abstract

1530677 Graphite articles SIAP SOC INDUSTRIALE AGGLOMERATI E PRODOTTI PETROLIFERI SpA 18 June 1976 [23 June 1975] 25308/76 Heading C1A Shaped graphitic articles are made by mixing together 10-50% by weight of a graphitic powder obtained from, or during the production of, graphite electrodes or electrode pastes, 80-28% of a coal or coke and 10-22% by weight of coal tar pitch; heating the mixture to about the melting temperature of the pitch; and feeding the resultant blend into a moulding press in which it is solidified into ovoid shapes, briquettes, or other predetermined shapes, or feeding it into a pelletizing plant. The coal or coke ingredient may be anthracite. A preferred mixture comprises 35% of the graphite powder, 50% of anthracite particles having a size up to 10 mm. and 15% of coal tar pitch having a Kraemer-Sarnow softening point of 70‹ C. The shaped articles are useful as a means of increasing carbon content in the production of cast iron or steel.

Description

Egg-shaped, briquette or pellet-shaped graphite agglomerates consisting of mixtures of 10 to 50% of very fine graphite according to the invention. dust, 80 to 28% coal and 10 to. 22%. binders such as charcoal pitch. The invention also relates to a process for the preparation of these agglomerates, in which the ingredients are mixed together, the mixture is heated to a temperature above the melting point of the binder, and after joining them together to a homogeneous mass is introduced into a molding press in which of desired shapes, or introduced into a pelletizing device.

The invention also relates to graphite agglomerates intended especially for use in the production of steel in a Martin furnace, in an arc furnace, in an induction furnace, as well as in the production of cast iron in an arc furnace, in an induction furnace, in rotary and furnace furnaces, and method of their production.

The use of 'coal' dust that is captured - in the various stages of the manufacture of graphite electrodes, electrode mastics, graphite anodes, etc., or arising from the grinding of these product wastes is a problem that has not been solved to date. This very fine graphite dust is in practice both usable in the powder state and it is very difficult to agglomerate it. Because of its fineness, it is commonly known as -dried grease, so-until now its agglomeration into useful products has never been successful.

Therefore, up to now, this very high-density graphite dust has been deposited in large pits where it is then covered with soil. In addition to the fact that this method of disposal entails economic losses, it also presents environmental problems.

Considering that said very fine graphite dust contains - from .55-% to 10-0.%. carbon, and further that this 'carbon' is present in an allotropic form of graphite, it is clear that by successfully solving the agglomeration of this dust into products which could be effectively and easily used in metallurgical plants to increase the carbon content of steels and cast iron, big profits can be made. The ecological advantage that is achieved is obvious, since such an agglomerate is not only dust-free but is very compact.

Various tests have been carried out to solve this very difficult process of agglomerating very fine graphite dust using coal pitch, but this requires the addition of at least 30% pitch so that the agglomerate can then contain at most 70% graphite dust. Such a high percentage of pitch gives a very hard product whose melt absorption is very difficult and which gives a very low yield in dissolved carbon. This product is therefore unsuitable for its intended purpose.

The above-mentioned drawbacks are overcome by an egg-shaped, briquette-shaped or pellet-shaped graphite agglomerate according to the invention which consists of a mixture of 10 to 50% ultra-fine graphite powder, 80 to 28% coal such as anthracite, coal, coke and 10-22% binders such as coal pitch, starch, lignin and derivatives thereof such as lignosulfonates, thermoplastic and thermosetting resins.

The invention also relates to a process for the production of graphite agglomerates, wherein the ingredients are mixed together in a suitable mixer, the principle of the invention comprising heating to a temperature in the range from the binder melting point to 40 ° C above the binder melting point and after It is fused together into a homogeneous mass, introduced into a molding press in which it is allowed to solidify into egg shapes, briquette shapes, or introduced into a pelletizing device. . .

The disclosed graphite agglomerate and the process for its preparation solve the problem of utilizing very fine graphite powder at the same time economic profit by providing a convenient material for use in metallurgical plants and eliminating the environmental problems that arise when graphite powder has to be disposed of as unusable industrial waste. .

The invention is explained in more detail in the following example.

The process according to the invention comprises a mixing phase together in a suitable mixer of very fine graphite dust, coal and a binder such as bituminous pitch, and a heating phase of this mixture of about 30 ° C above the melting point of the binder (about 100 ° C in the case of pitch). ° C], and feeding the amalgamated mixture to a molding press in which it solidifies into an egg shape, briquettes and the like, or a phase of feeding the mixtures into a lump machine.

The following components were used as starting materials for the invention: very fine graphite dust containing 70% graphite in an amount of 38%, anthracite in particles up to 3 mm in size of 40%, coal pitch with a softening point of 70 ° + 2%, in particles up to 5 mm, dried to about 5% residual moisture in an amount of 16%. These components are mixed together in a mixing cylinder into which steam is simultaneously injected, and - the mixture is maintained at a temperature of 90 ° C to achieve a melt-black coal pitch. After perfect mixing to a uniform mass, the mixture is fed to a cylindrical type press in which it is allowed to solidify to ovoid briquettes. The resulting product shows the following composition when - following chemical analysis:

carbon - 75%, sulfur - 0.85%, ash - 12%, volatile substances - 11%, the rest is moisture.

The graphite agglomerates according to the invention are not comparable to other similar products. This is particularly so since all attempts to achieve very fine graphite dust bonding by means of a binder have been unsuccessful. In contrast, the graphite agglomerates according to the invention are comparable with existing types of coal having the same analytical composition and which can be used as an additive to the molten bath in a metallurgical furnace. The graphite agglomerates of the present invention, in contrast to these types of coal, have a high percentage of carbon in the allotropic form of graphite, and therefore, when these graphite agglomerates are applied, carbon is advantageously dissolved in the steel melt in much greater amounts than when used.

Claims (2)

SUBJECT OF THE INVENTION Egg-shaped, briquette or pellet-shaped graphite agglomerate, characterized in that it consists of a mixture of 10 to 50% of very fine graphite powder, 80 to 28% coal such as anthracite, coal coal, coke and 10 to 22% binder , such as coal tar, starch, lignin and its derivatives, such as lignosulfonates, thermoplastic and thermosetting resins. 2. A process for the production of graphite agglomerates according to claim 1, wherein the ingredients are mixed together in a suitable mixer, characterized in that the mixture is heated to a temperature in the range of the binder melting point to 40 ° C above the binder melting point. they are joined together to form a homogeneous mass, introduced into a molding press in which they are allowed to solidify to ovoid shapes, briquette shapes, or introduced into a pelletizing device.