JPS5845171A - Hot melt refractories of spinel-periclase tissue - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot melt refractory having excellent corrosion resistance against steel slag.

Heat-melted refractories are made by melting refractory raw materials adjusted to the desired composition in an electric furnace, generally by pouring the molten water into a suitable mold, and then casting the cast material in a controlled manner. It is obtained as a refractory of the desired shape and size by cooling under certain conditions to cause the crystals to re-precipitate.
It can also be obtained by cooling each time and solidifying it again.

Heat-fused refractories are widely known as high-grade refractories that have a structure that is essentially different from that of ordinary 6-component refractories, which are made by sintering and bonding waste particles to each other.

The thread widely used for cast refractories is A1203-8in2. Al2O3, ZrO,, =
A1203-8in2. Mg0-Al2O3-Cr2
031 There are AI, O, -Cr203 series, etc. Among them, MgO-Al2O, -Cr2O3 yarn is unrivaled by other basic refractories in the steel and non-ferrous metal industries as a monobasic cast refractory. It has been valued for its excellence.

In other words, it has a stable crystal structure mainly composed of periclase and crim spinel, and has excellent corrosion resistance and shore wear resistance against various clay-based slags. It has been used in furnaces, vacuum degassing furnaces, and various melting parts for non-ferrous metals, and has achieved excellent results.

However, as the operating conditions of the industry become more severe, and as a result of the desire on the part of users for better products, it has become imperative to develop even better products.

The non-invention was discovered as a result of various studies from these points of view, and to explain it specifically, the present invention is based on a material selected from weight% ``c'45%''c'45% or more and Fe0. RO component and Cr2O3゜Al2O3 and Fe
It consists of a crystal structure mainly composed of a composite spinel phase and a periclase phase consisting of R2o3 components selected from , 03, and a small amount of glass matrix phase, and the weight% of each component is
If the Cr, 03/AX203 ratio is in the range of a5 to 55, the amount of MgO exceeding 4° and less than 60%,
CaO is 15% or less, Fe, ・O, (FeO is also Fe,
03) is 15% or less, and 51o2 is 5% or less, which is a refractory with a dense heat-fused spinel-periclase structure.

Here, MAC-EC (
To explain about Asahi Glass Co., Ltd. (product name), MAC-Eci
Standard chemical analysis values are Mg055% (wt%, hereinafter the same unless otherwise specified), A120315
%, Cr20318% l "0203"%,
5iO22,,6%, other Tie2. This fabric contains a small amount of CaO, and is clearly different from the fabric HV and silk fabric of the present invention. For example, if we take one Cr20s/Al2O3 ratio, the present invention is as described above (85 to 55, but 1
~2 pestle strength.

Essentially, due to these differences, the present invention has superior corrosion resistance against steel slag, etc., which is three times or more as described later. It is not clear why, but it is a major factor.''
No doubt.

In addition, the Cr2O3/Al2O3 ratio is higher than that of conventional MAC-EC, although it is the only product currently in use as a product.
Although the above basic cast refractories have been worked on, most of the -7 are around 8, and there is nothing that should be restricted by the present invention in terms of structure or chemical composition, and as a product. were just different things.

The present invention achieves unprecedented corrosion resistance and -
We have succeeded in providing an extremely dense hot bath fusion cast refractory with heat resistance, and the present invention will be specifically explained below.

In the present invention, most of the organizational components are RO-R', O, (R:
Fe.

It consists of a composite spinel represented by Mg, R': Fa, Al, Cr), and various raw materials mainly composed of chromium, alumina, and magnesia are heated in an electric furnace at a high temperature of generally 2800°C or higher. It is obtained by completely melting the hot water, casting it into a mold of a predetermined shape, and cooling it.Most of the refractory raw materials include magnesia clinker, chromite, Bayer alumina, and chromium oxide.

First, to explain the structure of the refractory of the present invention, the crystal structure of 45 or more is composed of composite spinel (MgO, FeO).
, (Cr, 03. Al2O3, F'e20.)
and in these spinels Cr2O,
The physical structure is dense with few pores, and the apparent porosity is 7 or less, often 5 or less, and can be easily obtained.

One of the reasons for understanding this invention is that it is a composite spinel in which spinel accounts for 45% or more of its crystal structure, and that there is a large amount of r203 (': Cr2O
It is thought that 3 constitutes these spinels and at the same time contributes to their strengthening in some way.

Composite spinel is FeO-Cr2O, MgO-Cr2
O3°F, eO-A1203. MgO-Al2O3,
MgO-Fe, ,O, Fe0-Fe2O.

7, respectively, or in the form of a partial solid solution.Among these, Cr2O5 plays an important role, and Fed-Cr2'3+Mg
○-Cr2'03 or other spinel Al2O3 or F
There are many forms in which Cr20a is solidly dissolved in a part of e, O,.

In the present invention, these spinel phases account for 45% of the total
This is because if the spinel phase is not sufficiently generated, a strong and dense refractory cannot be obtained as a heat-fused cast refractory, or the corrosion resistance against steel slag is lower than that of Cr2O.

This is because the composite spinel phase, which contains a large amount of components, is more stable than the periclase phase, so it does not provide more than twice the corrosion resistance of conventional practical products.

In addition to spinel, what constitutes the refractory of the present invention is a glass matrix mainly consisting of periclase crystals and a small amount of silicate.

In any case, the structure of the present invention contains 45% or more of spinel, periclase, and a small amount of silicate, and a desirable embodiment includes 45 to 65% spinel phase, 49 to 84% periclase phase, and glass matrix. phase is 1
It consists of 8 pieces of Cr, 03 and Al2O, which make up the spinel, and Cr2O is Al2O.
,, a5 times or more of O, 40-60% for MgO
It is necessary to keep it.

This is because first of all, if Cr, O, /Al, 03 is less than a5, a reinforced composite spinel will not be formed and sufficient corrosion resistance will not be obtained.
If there is too much Cr2O3, there is a possibility that Cr2O3 will evaporate in the high temperature range, so it is necessary to keep the maximum Cr2O3//A12o3 ratio at &5.

Next, regarding MgO, it has been confirmed that if it is less than 40% and it is more than 0%, better corrosion resistance can be obtained.
Since the corrosion resistance against slag with a high O/f:Jio ratio is slightly inferior, it is not optimal for the purpose of use, so in the present invention, an amount exceeding 40% is required. On the other hand, when the content exceeds 60%, not only does the spinel weave decrease, but the cast refractory is tt4. This is undesirable because the occurrence of H and cracks will increase dramatically and the yield will be extremely poor.

Note that the most desirable range of MgO is 45 to 55%.

Here, to explain the other components constituting the tissue, in terms of components, Cr2O, 30 to 60%, Al2O,
CaO 5-15%, 5i02 05-5%, CaO (1-
8-15%, Fe, 05 (of course it also exists as FeO-, but in this specification it is all calculated as Fe20.) is preferably limited to 4-10%, and the desired excellent composite is achieved. A spinel structure is obtained.

To explain each of these components, first, Cr2
If there is too little O, as mentioned above, the formation of spinel containing Cr2O3 will be insufficient, and if it is too much, C'r20. This is because the evaporation of

Regarding ^120s, if it is too small, there is no particular problem, but it is undesirable because it requires a lot of expensive Cr20s as a raw material, and if it is too large, the chromium ratio will be relatively reduced. ．． This is because if the amount is too high, it causes a decrease in slag resistance and a decrease in melting point.

Furthermore, Sio and Cao components, along with some Fe2O and components, are the main constituents of the glass matrix on the set line, and it is difficult to obtain a casting as a large ingot without them being present at all, so it is difficult to obtain a casting as a large ingot. - As mentioned above, the phase is desirably 1% or more and 2% or more; on the other hand, too much content impairs corrosion resistance, so it should be at most 8%, preferably 5% or less. For each seedling, if the Sin content exceeds 5%, the glass matrix portion will form into multiple pieces, and if the CaO content exceeds 15q6, monticerite with a low melting point will be formed, which is undesirable.

The cast refractories of the present invention having such a structure are considered to have significantly fewer bores (pores, cavities), which are unavoidable defects peculiar to cast refractories, and the apparent porosity is usually 10 cm. There are almost no more than 8~
It is now possible to obtain as much as 696 with less than 5 inches.

As a result, the refractory of the present invention has a corrosion resistance of about 8 to 5 times higher than that of currently commercially available chromium spinel-periclase materials compared to electric furnace slag for manufacturing. The corrosion resistance of silicate glass kiln flue slag is more than 8 times higher than that of flue slag, and the MgO content is less than 40% especially for steelmaking electric furnace slag with low operational turbidity and high CaO/SiOt ratio. It exhibits better corrosion resistance than most refractories of this type, and is resistant to C at high temperatures.
ab/Sin, including electric furnaces for steelmaking with high operating conditions, mixer furnaces, degassing furnaces, and non-ferrous metals/? ! It is suitable for many uses such as R-class melting furnaces and glass kiln flues.
Its industrial value is enormous.

Although the main purpose of the present refractory is to improve corrosion resistance, it not only has the strength necessary for cast refractories, but also has properties such as thermal shock resistance that will not cause any problems in use. That is confirmed.

In addition, the pulverized product of these materials can also be used as raw material particles for bonded refractories, rather than being crushed as lumps.

The present invention will be further explained by examples.

Examples Magnesia clinker, chromite, Bayer alumina,
A predetermined amount of chromium oxide, etc. was prepared, and 200 kg of these mixed raw materials were charged into an arc electric furnace and completely melted at a temperature of 2200° C. or higher for about 150 minutes. This molten raw material was poured into a mold having a shape of 1956x280ggx450y+++, and cooled to room temperature in a heat insulating material for each mold to obtain various cast refractories having the components and structures shown in Table 1.

Table 1 (marked Samples 4-7 are samples for comparison) The physical properties and corrosion resistance of these castings are listed in Table 2.

Table 2 (Note) Corrosion resistance is measured by cutting the sample and measuring 50. The results of the internal dense portion (with the same porosity value) using a rotating crucible type erosion tester in the following manner were compared using the Konkari Example Preparation Material (a typical commercially available example) 5. Corrosion resistance index (
Add 100 to the value obtained by dividing the corrosion of sample 5 by the corrosion of the sample.
(number multiplied by ).

Test method: 8pOX50X100. A crucible was assembled with the trapezoidal sample, and synthesized steelmaking electric furnace slag (C
aO/S soil 0. (basicity 1.6 and A4) was charged and heated from above with a propane-oxygen burner (1620°C x 16 hours and 1690°C x 5 hours) while rotating.

In addition to these corrosion test results, after the test mackerel “
Microscopic observation of the eroded surfaces of the samples revealed that most of the samples for the periclase phase absorbed 79g and turned black, but for the spinel phase, the product of the present invention hardly eroded the slag. In contrast, conventional products such as Sample 5 were observed to absorb slag and change color.

393-

Claims (1)

[Claims] L RO skin component Cr selected from MgO and Fe0, which accounts for 45 cm or more in terms of weight, 03. Al2O3 and Fe
It consists of a crystalline structure mainly composed of a waste spinel phase, a periclase phase, and a small amount of glass matrix phase, consisting of R2O3 component 75 selected from 2O3, and the amount %f''r203/A12 os ratio of each component is 35. - 55, the amount of MgO is more than 40% and less than 60%, the amount of CaO is less than 1.5, Fe2O, (FeO
A heat-melting refractory having a dense impinell-Rubélicase structure in which Fe, O, and Ni are less than 15 times and 5i02 is less than 5 times. 2 Spinel phase is 45 to 65 inches, periclase phase is 34 inches
49'% and a glass matrix phase of 1 to 8%. The heat-melting refractory according to claim 1, wherein the aCr203/Al2O ratio is 4 to 5. 4 MgO is 40-60%, cr, o, is 80-6
0%, Al, O8 is 5-15%, 5102 is α5-5
, CaO (18%, 15%, Fe2O, 4-10%)
A heat-melting refractory according to claim 1. (v) The heat-melting refractory according to claim 1, which has an apparent porosity of 5% or less.