DE1471337A1 - Process for the production of porcelain objects using blast furnace slag - Google Patents

Description

Patent attorney ;.

Dipi.-lng. E. bder

Munich 13, EllsabethstraBeS * 1471337

Note: NGK Insulators Ltd,

Munich, August 28, 1968

"Process for the production of porcelain objects using blast furnace slag "

The present invention relates to a method of making porcelain objects using Blast furnace slag together with quartz sand or other ceramic Substances as base materials.

The main aim of the present invention is generation of porcelain articles of higher strength and good machinability at lower cost.

Blast furnace slag occurs in ironworks as a by-product in an amount of around 800 kg per ton of pig iron, so that already various uses for it have been envisaged. For example, you have the slag by quenching solidify to a vitreous body and its latent hydraulic hardening ability for the production various types of slag cements, slag bricks,

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Lightweight concrete, slag wool and the like are more exploited. However, the use as a raw material for the manufacture of ceramic objects "has not yet been considered. On the other hand, since the blast furnace slag is available at a very low price, it can be used very well as Use raw material for special porcelain items, if the slag in question is at all suitable for it.

The invention is based on the discovery that the blast furnace slag as the main component of a raw material set Can be used for the production of porcelain if you have several masses to facilitate glass formation and the nucleating agent for converting the glass structure into a crystal structure is added by heat treatment. The mass is then melted and molded, and the molded articles are subjected to a heat treatment subjected. These special porcelain objects * and of course also equal or even surpass those of ordinary porcelain objects.

In carrying out the present invention, the blast furnace slag is used as the main component of the raw material with the addition of a nucleating agent composed of one or more of the following substances - Cr ₂ O ^, MnO, CaF ₂ , P ₂ O ₅ , TiO ₂ and the glass-forming substances such as Feldspar, limestone, picrite (containing magnesite) and dolomite in the following proportions: 40-70 % SiO ₂ , 5-15% Al ₂ O ₃ , 15-35% CaO, have properties that are similar to those of ordinary glass objects

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2 - 12% MgO, 2 - 12% Na ₂ O and 0.5 - 10% of the nucleating agent. The mixture is melted into a flow of gals, which makes it easier to incorporate into the molds or other design. The shaped pieces are then subjected to a heat treatment at a temperature of 700 ° -900 ° and from 900 ° -1100 °, whereupon the object is slowly cooled for the purpose of 'formation of crystals or a

crystalline structure, like porcelain objects from blast furnace slag can get. According to the invention, the slag available at a very low rate becomes used as a raw material, so that the porcelain objects made from them also have very low cost prices.

The production of porcelain objects by the method according to the invention will be explained in more detail below will.

The composition of the blast furnace slag produced in Japan is given in Table 1 below:

Table 1

SiO ₂ 30 - 34 % MgO 2 - 5 Al ₂ O ₅ 14 - 18 % K ₂ O 0.5 - 1.0 FeO under 1 % Na ₂ O 0.5 - 1.0 MnO 0.8- 1.5 % S. 0.9 - 1.2 CaO 39 - 42% TiO ₀ 0 2

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The blast furnace & chlacke in itself has a very high melting point and is difficult to melt in an ordinary tank furnace for glass, so that Si0 _OJ CaO, MgO, Na ₀ O, etc. added

must set to melt at a temperature of 1300 - 1400 ° and pour the melt at this temperature in molds or otherwise deform, similar to the manufacture of objects from glass. That way The glass objects obtained must have the basic composition of the glass described below, so that they get a crystalline structure during the subsequent heat treatment. In the entire glass mass must be about 95% of such a composition must be included.

label. Ie 2

SiO Al _{0 0} O _7, CaO MgO Na ₀ O ^ Eernbildungsf ° F medium

- 70 5 - 15 15 - 35 2 - 12 2 - 12 0.5 - 10

The composition of the raw material is given in two examples in Table 3 below:

Table 3

I. Blast furnace slag 30 - 70 %

Quartz sand 30 - 70%

Calcium carbonate 10 - 30 %

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2 - 42 2 ■ - 12th ο, 5 - 10 40 - 70 30th - 60 0 - 5 ο, 5 - 10

Magne siumc art »onat Calcined soda. Nucleating agents

II. Blast furnace slag .., Matrönfeldspar. "". Calcined soda .., nucleating agent

Examples of nucleating agents are given in Table 4 below:

Tabel Nuclear Forming Agent Raw Material;

Cr 0, potassium dichromate

MnO pyrolusite

CaF ₂ (or NaF) fluorspar (or sodium fluoride)

P ₂ Oc phosphoric acid

TiO ₂ titanium dioxide

The nucleating agent to be used in the present invention, which consists of one or more of the substances listed in the table is extremely suitable, and the substances in Table 4 are relatively easy to use.

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The masses described above can be used at a temperature from 1300 - 1400 ° easily processed into a glass flow and, as desired, in one of the usual shapes to manufacture deformed by glass objects. The resulting glass objects then become a little less in the long run than three hours at a temperature of 900 - 1100 ° subjected to a final heat treatment.

During the heat treatment, the heat can be increased by 100 - 400 ° per hour up to the softening point, which can be maintained or can not hold, whereupon the temperature can be increased by 200 ° every hour or in a shorter period of time to 900 - 1100 ° increases.

In this case, the heat treatment up to the softening point of the glass can be carried out at such a speed that no cracks occur in the glass objects. The temperature should be kept close to the softening point be, but the reaching of the glass up to the highest temperature of the heat treatment must be avoided. The temperature rise is less than 200 ° per hour limited to crystal formation to the innermost part to allow the glass object to penetrate. In the case of thin-walled fittings and if the same are somewhat supported, there is no risk of deformation To avoid this, the pieces do not need to be kept at a temperature close to the softening point of the glass will. The temperature can drop by less than 200 ° up every hour

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Rise to a height of 50-100 ° below the softening point in order to bring about a crystalline structure. When examined with X-rays, it was found that the crystals of the porcelain objects obtained in this way form a very fine-grained rigid solution of the type BfeUjO-GaO (MgO) -Al ₂ O ^ -SiO ₂ . According to the invention

Porcelain objects obtained by the method had a bend'S

strength of 2000 - 3000 kg / cm and a softening point of over 1000 °, which was previously not possible with the usual porcelain objects.

The reason that the composition of the set for the vitreous articles is restricted in the manner described above can be attributed to the fact that the compositions within the range of Table 2 are most suitable for glass formation and crystallization by heat treatment, as by experiment has been confirmed. Addition of the nucleating agent below the lower limit of the above range has no substantial effect, while when the amount exceeds the upper limit, the crystal grain becomes coarse and large and the properties of the products are lowered. Whether or not the glass objects according to the invention can be brought to crystal formation by the heat treatment depends mainly on the proportions of CaO and MgO as well as the nucleating agent, such as CrpO *, MnOp, PpOc, CaIo or TiO ₂ , which are very important are. With less than 15 % CaO and with less than 2% MgO, the formation of a

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of crystals never occur, even if the other proportions of the mass are appropriately chosen. The upper limit of the proportions of CaO and MgO, i.e. 55 % and 12%, respectively, is to be regarded as the maximum limit value with regard to the special molding process. In the usual molding processes for glass objects, devitrification and a large temperature change in viscosity close to the mold temperature occur, so that according to the invention, the glass objects must necessarily be without glass. With such glasses, if they are melted at high temperature and quickly cast, the desired shaped pieces can be obtained. obtain. The other ingredients within the above range are limited in their proportions by the proportions of CaO, MgO and the nucleating agent. This area cannot be represented graphically, as the effect of smaller proportions in the blast furnace slag is great, but the following tendencies can be observed:

(1) With a large proportion of nucleating agents: For at least 10 % of the nucleating agent causing the crystallization, a range of 15 - 35 % CaO, 2 - 12% MgO, 6 - 12% STa ₂ O, 5 - 15 % Al ₅ O _{3 is required} and 50 - 70 % SiO ₂ suitable for the production of crystallized objects, while outside this range the products show a low degree of crystal formation and softening phenomena during the heat treatment. They also have a lower strength, and these phenomena become with increasing proportions of Na ₂ O and Al ₂ O ₅ even larger.

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(2) When the proportion of nucleating agent is smaller: The proportions of CaO and MgO are preferably large. With a proportion of less than 0.5 % of the nucleating agent, no crystal formation occurs; with less than 20 % CaO, the degree of crystal formation is low, while with more than 30 %. CaO and 10 % MgO, if the proportions of MgO and Al ₂ O _{5 are} closer to the lower limit value, wollastonite (calcium silicate) crystallizes out during the melting process, so that there is a tendency towards devitrification.

When deforming the above mass, you can create different products each with special properties, namely:

(1) Ceramic heating elements by embedding electric heating elements ;

(2) High magnetic composite porcelain articles Properties or high permeability by embedding magnetic material in the fittings}

(3) Porcelain articles with high thermal conductivity and Strength by adding a small amount of BeO to the mass egg

(4 ·) an excellent putty for joining Porcelain objects by adding an appropriate amount of glaze material.

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Basic mass

Example Example Example Example Example Example 1 2 3 4 5

Ha ₂ O 5.5 6th 8th 4th s e 8th - 4th Al ₂ O ₃ 7th 6.5 15th 6th 10 15th CaO 26th 15th 15th 33 33 30th MgO 4th 3 3 7th 7th 10 SiO ₂ 57 66.5 56 49 41 40 Cr ₂ O ₃
MnO ₂ 2 2 2
1 CaF ₂ 10 - P ₂ O ₅
TiO ₂ 5 10 Mixed Mas

Ex. Ex. Ex. Ex. Ex. Ex. 1 · 2 3 4 5 6

Blast furnace slag 34 37 37 34.2 34.2 70

Matron

feldspar - - 55.2 - 30.3

EaIz.Soda 6.4 9.8 7.5 4.8 8.5 3.8 nium—

hydroxide - - 1.9 - - 3.1

Calcium Oxide 13 _ _ 21.8 21.8

magnesia

(Pricrit) - 1.9 1.9 - - 11.8

Dolomite 7 - .. - 23 23

Quartz sand 38 54.5 - 38 24 16

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Potassium dichromate

Pyrolusite J ¹ IuB late ο-phosphorus.

Titanium dioxide

10

6.9

3.9

2.5

3.9 1.2

10

Conditions of heat treatment and characteristics

Ex. Ex. Ex. Ex. Ex. Ex. 1 2 3 4th 5 6th Heat re
plot 700
1.5
Hours. 700 °
1.5
Hours. 700 °
1.5
Hours. 720 °
1.5
Hours. 720 °
1.5
Hours. 720 °
1.5
Hours. Holding tempe
rature 1000
1 H. 950 °
3 hours. 950 °
1 H. 1000 °
1 H. 1000 °
1Sd. 1000 °
2 hours. Heat dissipation elongation _r
coefficient 63x10 ' ¹ 60x10 " ⁷ 60x10 ~ ⁷ 65x10 ~ ⁷ 7Ox1O ~ ⁷ 68x10 ~ ⁷ (25 - 325 ^o) Softening
point over
1000 ° above
1000 ° 980 ° above
1000 ° above
1000 ° . above
1000 ° Flexural strength
speed ρ
(kg / cm) 3000 2000 2100 2500 2600 2800 hardness
(Enoop ^
(Kg / mni) 800 MM 750 mm. Acid resistant
speed
(JIS powder
method) 1.0 - - - - -

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Claims (9)

Patent attorney Dlpl.-Ins-E.Eder Munich 13, Eiisabethstraße34 - 12 - Claim Process for the production of porcelain objects using blast furnace slag, characterized in that the blast furnace slag is used as the main component, with the addition of a nucleating agent consisting of one or more of the following substances: chromium oxide, manganese oxide, Calcium fluoride, sodium fluoride, phosphoric acid and titanium dioxide, as well as a glass-forming material, e.g. Quartz sand, calcium carbonate, magnesium carbonate, calcined soda, etc., in. the following proportions: 40 - 70% SiO ₂ , 5 - 15 % Al ₂ O ₅ , 15 - 35 % CaO, 2 - 12% MgO, 2 - 12 % ITa ₂ O and 0.5 - 10 % of the nucleating agent, whereby these substances must represent more than 95% of the total glassware, whereupon this Ge.-mixture is melted and shaped in order to then subject the shaped pieces obtained to a heat treatment so that a crystalline structure is formed. 9 0 9 8 G 5/0 8 6 8 ιλ I J- · «---