DE1817491A1 - Process for the production of a molded body from a powder-tar system - Google Patents

Description

DR. E. WIEGAND DIPL-ING. W. NIEMANN 1817491

phone. 55547Ä 8000 MONKS December 15, 28, 1968

TELEGRAM BI KARPATENT 'NUSSBAUMSTRASSE 10

w. 14 065/68 13 / never

Kureha Kagaku Kogyo Kabushiki Kaisha Tokyo (Japan)

and

Kaoru Urneya
Sendai-shi (Japan) '<

Process for the production of a shaped body from a powder-tar system

There are many industries in which a molding or compact is formed using a powder-tar system is obtained from which a final or finished product as such or after subjecting the molded body to a heat treatment is obtained. Such molded bodies include, for example, carbon electrodes for large electric furnaces, refractory carbon materials, silicon carbide refractory materials and basic firebricks mainly consist of fireproof dolomite bricks.

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The main purpose of the invention is to improve the quality of a molded or pressed body or its final one Commercial article, being a tar-like material used for molding or pressing a powder-tar system is to be used, a heat treatment at a relatively high temperature before the Subjected to molding or pressing treatment.

The above tarry material generally consists of coal tar and pitch or tar, where these materials are obtained from a coal well or asphalt from a petroleum well, and in ordinary use for molding or pressing a powder-tar system, the tar or pitch source can be separated or mixed or with a solvent with a low boiling point such as coal tar or petroleum fraction material A proportion of 0 to 60 # are always used. The one commonly used

t
tarry material · having a softening point of 45 to 90 ⁰ C and a melting point of 85 to l40 ° C.

Disadvantages encountered in carrying out powder molding or molding using these tarry materials occur, for example, with reference to the production of a tar-bound Ddbmitziegel in the various industries mentioned above. Calcined dolomite powder is used as Raw material and fine magnesia powder for the formation of a ceramic bond In a kneading machine

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the type of heating introduced, at a temperature (85 to 14O ° C) increased to about the melting point of this tarry material and then mixed with the flowing tarry material that was previously ^{heated to a temperature above its melting point (95 to 150 0} C) was kneaded. After kneading, the temperature of the mixed system is brought to a temperature close to the softening point of the tar used (45 to 90 ^° C., in certain cases close to room temperature) and the mixture is molded under high pressure at this temperature. After molding, the molding is placed in a dry distillation furnace after the temperature has been lowered to approximately room temperature, or in the case of molding, it is placed immediately at room temperature and then subjected to a dry distillation heat treatment.

"The properties of the molded body and the brick or stone product at this point are essentially influenced by the heat treatment temperature, as well as by the softening behavior, the volatility and the charring or coking behavior of the tarry material used. If the heat treatment is carried out at a low dry distillation temperature (250 to 450 ⁰ C) is carried out, there is a relatively little evaporation of volatile materials from the tar-like material, the majority of which remains in the bound parts between the grains.

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sem Pall, the bound part proportionately under this condition is strong and the stone or brick product has sufficient strength for transportation or the handling involved in furnace manufacture, shrinkage of sized brick or occurs Stones that, for example, lead to a considerable defect or fault in the properties as a lining material of a Converter leads if the stone product is used as furnace material, as it is exposed to high temperatures whereby an evaporation of the tarry material takes place.

Another disadvantage is that the tarry

artip; e material when used as furnace material on a

from
Part / high temperature evaporates and deposits on a part of low temperature in the built stone or furnace material, whereby a local accumulation of the tarry material and in certain ^ extreme cases an erosion phenomenon is obtained in which the tarry material thus accumulated due to the change in temperature Formation of cavities flows out. Therefore, the user must pay attention to this.

On the other hand, when the heat treatment temperature in a dry distillation furnace is increased (450 to 650 C), in order to overcome these disadvantages, the tarry material evaporates and a part thereof is coked. Accordingly, there is the bound part consists of a mixture of tar and the coked material, which as a result of pyrolysis during

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the dry distillation heat treatment. In this case, the cavitation phenomenon and shrinkage in use are favorably reduced, however, it is inevitable that the strength of the bonded part is lowered and the handling properties at normal temperature in transportation and Furnace manufacturing are deteriorated.

As described above, the usually grazed tarry material having, for example, the properties listed in Table I below, gives high strength at normal temperature in the case of a low dry distillation temperature, for example lower than JOO ⁰ C, but evaporates when using the stone or Brick product at one. Temperature above 500 ⁰ C, thereby often drawbacks, such as shrinkage and AushÖhlungserscheinung obtained. In the case of a high dry distillation temperature, for example above 50O ⁰ C, the shrinkage when using the stone product and the hollowing phenomenon can be reduced, but the strength is reduced at normal temperature and the transport and the furnace production are disadvantageous, accordingly there is no temperature for Dry distillation heat treatment capable of completely eliminating both drawbacks if such a tarry material is used. .

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SAD ORIGINAL "

Expansion i Curse \ sphalt I. solid coal tar and Firm chungs term Curse speed Tabel Point
( ⁶ G) Be term Firm at Various properties of was standing Be speed higher share was standing at Tempe sample Ms _n share normal rature 72 30O ⁰ C
{%) until Toiüpe- (kg / cm 3 50O ⁰ C
(fo) rature 200 62 23 (kg / cm ² ) 2 35 192 53 30th Coals tar asphalt

The above statements are restricted to the production of a tar-bound dolomite dceine; however, similar problems have been encountered in all other industries, e.g., electrode industry, industry für.feuerfestematerials or the like encountered.

According to the method according to the invention, a tarry material to be used becomes a special heat treatment, which will be explained in more detail below, before molding or pressing to modify tarry material, thereby overcoming the disadvantages outlined above, i.e. the quality a molded body from a powder-tar system or its final commercial product is improved.

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Disadvantages that occur in a powder-tar system and in its heat-treated article, are usually related to the properties of the tar, e.g. (1) softening behavior (melting point), (2) volatility and (j5) coking behavior after evaporation. A high melting point usually means high strength at normal temperature, which is suitable for use as a brick or refractory stone. A low volatility means a large one Amount of residual carbon after heat treatment, this being for use as brick or refractory stone suitable is. A higher level of residual carbon is beneficial for a refractory material because it does Prevents molten iron or slag from entering.

In general, the coking of a tarry material, as described above, does not "only depend on the" Volatility (content of low-boiling fraction), but also on the chemical composition. In the event of of a petroleum-type tarry material, the degree of coking is not good due to thermal decomposition by heating and the decomposed constituents which are to be vaporized and given off as a result of the higher Content of aliphatic hydrocarbons and aliphatic side chains.

In contrast, in the case of using a particular tarry material according to the invention, such as described below, the coking yield is excellent

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net, since there is hardly any thermal decomposition due to heating and dehydration polymerization due to the higher content of aromatic hydrocarbons progresses effortlessly with a relatively high molecular weight.

In the method according to the invention, the production of a molded body of the powder tar Arfc, a dry-distilled body or calcined body with a higher bond strength than the known objects at any temperature from a low temperature to a high temperature, whereby the Disadvantages of the known tarry materials can be overcome by using a tarry material is subjected to any of the various pre-compression heat treatments set forth below to thereby a tarry material with a high melting point, low volatility and high coking behavior to win.

According to the invention, five modes of heat treatment of the tarry material are employed, as follows are listed:

Working method A :

Any petroleum type tarry material, coal source tarry material or any mixture obtained by mixing these tar products is subjected to the heat treatment before use. The temperature is between einge- I50 to 55O ⁰ C

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This temperature is higher than / äieie in the usual heat treatment (95 to 150 ⁰ G), whereby these tar materials become liquid and volatile substances are thoroughly removed. The tar material modified or treated in this way is used as the tar raw material.

Work way B:

Any tar-like material of the Erdölart, any tar-like materials from coal sources or any mixture of these Teermaterialien is subjected to a heat treatment at 150.bis 55O ⁰ C before use, where oxygen, nitrogen, air, chlorine, hydrogen chloride or the like. is blown into it or the presence of an inorganic salt, for example iron chloride or aluminum chloride, is brought about. The tar-like material thus modified or treated is used as a tar raw material.

Working method C:

One or more of the usual tar and pitch materials from coal sources and asphalt from petroleum sources are not used, but a tarry material, which was prepared at a high temperature, said pitch at a temperature above 900 ⁰ C and below 230O ⁰ C of any type of Kohlenwasserstoffrohrnaterialien is formed (see. Japanese Patent Application 71920/1967).

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- ίο -

Working method D:

The heat-treated at a high temperature pitch material according to operation of C obtained is further subjected to a heat treatment at I50 to 55O ⁰ C before use. The pitch or tar material thus treated is used as a pitch or tar raw material.

Working method E:

When carrying out the modification treatment according to the procedure D, the pitch or tar material becomes eira? Subjected to heat treatment at 150 to 550 ° C while Oxygen, nitrogen, air, chlorine or hydrogen chloride is blown into it or the presence of one inorganic salt, e.g. ferric chloride or aluminum chloride, is brought about. The tar material treated in this way is used as a tar or pitch feedstock.

'The five modified or treated tar or pitch products described above have a H / C ratio (hydrogen atoms / carbon atoms ratio) of less than 1.0 and contain such aromatic substances of high molecular weight in order to high melting point, lower volatility and excellent carbonization yield or To get coking. Examples of the powder materials used according to the invention as refractories The material is basic powder, e.g. dolomite powder, magnetic

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sium oxide powder (MgO), calcium oxide _{powder (CaO) and chromium oxide powder (Cr 2} O ₇ ), neutral powders, e.g. thorium oxide powder (Th ₀ O,), yttrium oxide powder (YpO ₇ ) and aluminum oxide powder (ΔΙρΟ ^,) and acidic powders, e.g. silicon dioxide powder (SiOp) * Quartz glass powder (silica glass powder) and mullite powder, and for the production of electrodes and special refractory materials carbon powder (amorphous and graphitic), silicon carbide powder, boride powder and nitride powder.

Examples of finished products are all basic refractory materials including dolomite bricks or -bricks, carbon electrodes for large electric furnaces, electrodes for batteries, refractories Carbon-based and silicon carbide refractories.

ⁿ a, the modified or treated pitch or tarry material generally used according to the invention has a high melting point, in the case of producing a shaped body of powder / tar type a working condition at a higher temperature than the known kneading and ^w ormpreßbedingung is required, however, the quality of the product is remarkably improved. Moreover, using the procedure described below, this purpose can be achieved even under a similar condition as that of the prior art. 80 is made taking advantage of the fact that the pitch or tar material used, treated or modified according to the invention due to its high

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Melting point and hcäiaromatischen behavior is easily pulverized, the modified pitch or tarry material prior to molding pulverized, mixed with a Pulveraggregat.in adequately at a lower temperature than the melting point of the pitch or Teermaterials, kneaded with a suitable amount of coal tar fraction or ^w rdölfraktion and then press-molded. By doing this, an excellent molded article having a high bulk density and a high compression ratio can be obtained. strength can be obtained.

Hie invention is described below with the aid of an example of operation explained in more detail with reference to dolomite stone.

example

100 kg of a powder mixture consisting of 60 wt .- ^ nolomitpulver (diameter 5 mm to 0.5 mm, continuous grain size distribution) and 40 wt .- ^ of a fine Magnesluraoxydpulvers (diameter less than 0.05 mm, continuous grain size distribution) were in a Introduced kneading machine with an internal volume of 100 liters and ^{kneaded with stirring at a temperature of 10 to 15 0} C above the softening point of each of the tar or pitch materials given in Table II below. Then, each of the pitch or tar material previously heated to about the melting point in order to impart flowability thereto was flowed into the kneading machine and kneaded sufficiently. The mixture

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was then placed in a metal mold having dimensions of 50 × 50 × 80 μm and press-molded under a pressure of 500 kg / cm. The resulting shaped body. of the material characteristics was evaluated as subject to such a provision, although a variation of about - 5 mm in the length ichtung ^ of 80 mm occurred never "esults of this evaluation are shown in Table II below:

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- to sample Treatment
lung
working
way 0 9 8 2 9/1 Coal tar A. co
«Η asphalt A. asphalt B. More pyrolitical
Tar * C. Pyrol.ytiseher
Tar *
More pyrolitical
Tar * D.

Table II

(D (2) (3) (4) (5) (6) (7) (8)

400 2 no 125 0 4th 60 310 400 3 no 120 0 30th 55 210 250 12th Sour
material 125 0 45 57.. 270

no no no 150

360 2 no 180

350 1 Sauer- 200 0
material

44 75 300 30 76 320 15 87 320

Note on the table:

(1) heat treatment temperature (° C);

(2) heat treatment time (hours); O) treatment agents!

(4) softening point ( ⁰ C);, -

(5) Volatile constituents up to 300 ^° C.

(6) Volatile constituents up to 500 ^° C.

(7) normal temperature compressive strength (kg / cm);

(8) High temperature compressive strength (kg / cm).

High temperature pyrolytic tar obtained by thermal cracking. from Kuwait crude oil at 1200 ⁰ C by means of the flame cracking system using a combustion gas at 2000 ⁰ C.

It can be seen from these results that the normal temperature strength and the strength at & oher temperature which increases the strength after heat treatment by dry distillation when using the Tar products according to Procedures A and B, burn up with Table I, are improved. This tendency is particularly noteworthy in the examples using the tar products from procedures C, Ti and E, being the strength at normal temperature two to three times that of the known article and the strength after dry distillation (Strength at high temperature) is 1.5 times that of the known object,

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In the production of a molded body from the powder-tar system, as described above, the strength at normal temperature and the strength after dry distillation of the molded body by using a pitch or tar material of the petroleum type or the coal type, the preceding a particular Had been subjected to heat treatment at 150 to 550 ⁰ C, in particular a tar or pitch material that was specially prepared so that it was subjected to a special heat treatment at a high temperature of above 900 ⁰ C during the tar or pitch preparation, one Teeroder pitch material that had been obtained by subjecting the specific Teeroder pitch thus obtained material to a second heat treatment at I50 or 55O ⁰ C, or a Teeroder pitch material by injecting the above-mentioned gas in the second heat treatment to further promote Response obtained could be improved significantly. r> i * e moldings produced and products have a higher bonding strength at höheer temperature of normal temperature to an operating temperature of up to 1500 ⁰ C than the known products. the disadvantages of the previous technology; in remarkable. Wise to be overcome, according to the prior art, the high temperature behavior with improvement or increase in the behavior at normal temperature was ver worsened or vice versa.

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The advantages according to the invention naturally also occur in all other cases of basic refractories Stones other than dolomite stones, carbon electrodes for large electric ovens. Electrodes for electrolytic cells, carbon-based refractory materials, refractories Materials made of silicon carbide or the like. on.

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Claims (6)

Claims 1. A method for producing a molded body from a powder-tar system, characterized in that one subjecting a tarry material to be used for compression molding to a heat treatment before compression molding and thereby modifies and improves the quality of the molded body and its final commercial product. 2. The method according to claim 1, characterized in that a tar-like material is previously subjected to a heat treatment at 150 to 550 ⁰ C and then used for compression molding. 3. The method of claim 1 or 2, characterized in that a-tar-like material above a heat treatment at I50 to 55O ⁰ C under inputs · bubbles of oxygen, chlorine, nitrogen, air or hydrogen chloride or in the presence of an inorganic salt such as Iron chloride or aluminum chloride subjects to promote the modification reaction and used the product modified in this way .. 4. The method according to claim 1, characterized in that there is used a tar-like material which is subjected to a heat treatment at a very high temperature in the range of ⁰ to 2300 C · 9OO was. 909829/135 7 5. The method according to any one of claims 1, 2 or 4, characterized in that there is used a tar-like material that was subjected to heat treatment at a high temperature has been subsequently subjected to a high temperature heat treatment at 150 to 55O ⁰ C in the range 900-2300 ⁰ C and . 6. The method according to claim 1, characterized in that a tarry Mateiäal is used, the first heat treatment at high temperature at 900 to 2350O ⁰ C and then a second heat treatment at high temperature at 150 to 550O ⁰ C with blowing oxygen, chlorine , Nitrogen or air or in the presence of an inorganic salt, e.g. . Ferric chloride or aluminum chloride, had been subjected to the modification reaction to further promote it. 909829/135?