JPS61201657A - High density sintered magnesia-chromium clinker and manufacture - 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] [Industrial Application Field] The present invention provides a high-density sintered magnesia-chromium clinker (
(hereinafter referred to as mag/croclinker) and its manufacturing method. More specifically, the present invention relates to a mag chrome clinker suitably used for manufacturing direct bonded magnesia chrome bricks (hereinafter referred to as direct bonded mag chrome bricks) and a method for producing the same.

[Conventional technology]

In recent steelmaking processes, for example, with the advent of the ladle refining method, conditions have become stricter for the refractories used, and there is a demand for refractories with particularly excellent high-temperature properties. Various studies are being conducted to improve the quality of maguro bricks, such as reducing the Sin content or adopting high-temperature firing methods. The aim of such high-quality steel was to increase the direct bond area between magnesia and chromite or between magnesia and secondary spinel. Among these methods, a method of blending sintered mag chrome clinker in addition to magnesia clinker and chromium ore as raw materials for bricks has been developed as an effective means, and good results have been obtained.

Japanese Patent Publication No. 29-3775 states that the chromium oxide content is 4.
A method is disclosed in which fine magneside powder is added to fine chromite powder of 0 to 45 inches, kneaded with magnesium chloride, and calcined to produce mag chrome clinker. The same bulletin states that 50% of fine chromite powder with a chromium oxide content of 4446%,
An example is disclosed in which 50% of magnesite fine powder is kneaded with a magnesium chloride solution and fired to obtain a mag black clinker.

Japanese Patent Publication No. 43-28714 discloses that magnesia containing 098% or more of Mg and less than 2% of SiO, and low-silica chromite powder with less than 5% of Si and less than 150 mesh on anhydrous basis are used as raw materials. The ratio of magnesia to chromite is 70:30 or more, and the StO content in the entire mixture does not exceed 3% in terms of fired product, and after granulation and molding, the temperature is 1800°C or more. A method for producing a magnesia-chromium based clinker is disclosed.

The same example includes magnesia vs. Cr, 0. 46.1
It is described that a Mag-Chrome clinker having a bulk specific gravity of 30 was obtained by firing a mixture of 80:200 ratio of chromite containing 2 parts by weight of chromite.

Japanese Patent Publication No. 47-15687 describes a method for producing magnesia spinel clinker using seawater magnesia and chromite as raw materials, in which the SSO content after blending the raw materials is 20% or less in terms of the fired product, and By mixing 65 parts of seawater magnesia and 35 parts of chromite fine powder with a diameter of 44 microns, press-molding the mixture, and firing it at a high temperature of 1900°C or higher, a highly heat-resistant spalling with dense hot strength is created. A method for sintering a high purity magnesia spinel clinker that produces a sintered body with excellent properties is disclosed. Furthermore, in the example, the apparent porosity of the sintered mag black clinker changes as the blending ratio of seawater magnesia and chromium ore changes; when the blending ratio is 80:20, the apparent porosity becomes 24%
It is stated that in the case of 70:30, it will be 13%, and in the case of 65:35, it will be 42 inches.

In addition, Kawasaki Rozai Edane A4.1973, page 40, has a report titled About Mag and Black Renka. Table 4 of the same report discloses a Mag Kurokuri 7 car with an MQO content of 86°0% and a bulk density of 14317/cps.
472 inches, bulk density λ31-&32g/cm'' mag-black clinker, MQO content 8&31 inches, bulk density 3.0
2~106g/an'' mag black clinker and M
QO67,819b.

Mag black clinker with bulk density 3.09-116 g/cm'': as shown.

[Problems to be solved by the invention]

However, as described above, all of the mag and black linkers obtained by the prior art have properties such as bulk density that still need to be improved. In particular, in order to withstand the more severe refining techniques of recent times, conventional mag and black bricks are insufficient in terms of quality, and there is a need for sintered mag and black clinkers that are of even higher quality and economically cheaper. .

An object of the present invention is to provide a high density sintered magnesia-chromium based clinker.

Another object of the present invention is to provide high-density sintering with improved sinterability, which is a particularly important property for improving the quality of direct-gened magnesia-chromium clinker among the various properties of sintered magnesia-chromium clinker. An object of the present invention is to provide a magnesia-chromium clinker.

Still another object of the present invention is to provide a method for producing a high-density sintered magnesia chromium clinker by a method completely different from conventional methods.

The focus in improving the conventional sintered mag/croclinker was to examine the chemical composition and particle size of the raw material chromium ore, as well as the firing conditions.

However, as described above, according to the conventional method based on this point of view, a high-density sintered magnesia-chromium clinker having an MQO content of 62% or more and a bulk density of at least 145 g 15 t'' has not been obtained.

[Means and Effects for Solving the Problems] According to the present invention, the above-mentioned objects and advantages of the present invention can be achieved by: 30% or less of other oxides with a chemical composition of 20% or less and at least 145 g/ctyt
This is achieved by a high-density sintered magnesia-chromium based clinker characterized by having a bulk density of .

According to the present invention, the above-mentioned high-density sintered magnesia of the present invention
Chromium-based clinker is produced by adding a water-soluble iron compound to seawater, bittern, or brine, and adding dolomite slag, lime, or their hydrates substantially simultaneously or after the addition to produce mainly magnesium hydroxide. A method for producing a high-density sintered magnesia-chromium clinker, which is characterized by producing a precipitate consisting of: mixing the precipitate thus obtained with chromite powder; and sintering the resulting mixture. I can do it.

The magnesium-containing aqueous solution used in the method of the invention is seawater, bittern or brine, preferably a decarbonated aqueous solution thereof. A decarboxylated aqueous solution can be obtained by adding an alkaline compound such as lime or calcium hydroxide or a strong acid such as sulfuric acid to seawater, bittern or brine according to known methods.

It is well known that magnesium hydroxide is precipitated by adding an alkaline compound such as calcium hydroxide to such a decarbonated aqueous solution, but in the method of the present invention, there is a time when an alkaline compound such as lime is added to the magnesium-containing aqueous solution. It is essential that the water-soluble iron compound is added substantially simultaneously or prior to the addition of the alkaline compound.

By using the magnesium hydroxide thus produced, it becomes extremely easy to produce the high-density magnesia-chromium clinker targeted by the present invention.

The method of the present invention, in which a water-soluble iron compound is added to an aqueous magnesium-containing solution substantially at the same time as or before adding an alkaline compound such as lime, produces a high-density magnesia-chromium based clinker having an increased density. Although the reason for this is not necessarily clear, according to the method of the present invention, when lime, etc. is added to a magnesium-containing aqueous solution containing a water-soluble iron compound, fine iron hydroxide particles are first generated, and then magnesium hydroxide is formed using these particles as nuclei. This is thought to be due to the fact that the water-soluble iron compound acts advantageously in forming the precipitate of magnesium hydroxide, but on the other hand, there is little chance of forming a low-melting compound during calcination.

The water-soluble iron compound may be an inorganic or organic acid salt of divalent iron or trivalent iron. Mineral acid salts, such as inorganic acid salts, are preferred iron compounds. Examples of such water-soluble iron compounds include inorganic acid salts such as iron chloride, iron sulfate, iron nitrate, iron phosphate, acetate, iron benzoate, p-)luenesulfonate, and the like. Water-soluble iron compounds can be added to the precipitate, which mainly consists of magnesium hydroxide, in amounts amounting to 0.2 to 5% by weight on a scorching basis.

The addition of an alkaline compound such as lime to a magnesium-containing aqueous solution containing a water-soluble iron compound is carried out so that the pH of the aqueous solution becomes about 1.0 g or more, which produces magnesium hydroxide, but preferably at a pH of 11 or more, e.g.
This is done so that H11-12 is obtained. When the pH of the aqueous solution exceeds 10.8, some excess of the alkaline compound will be added, thereby making it possible to produce magnesium hydroxide with a lower boron content, thus also resulting in less boron. It is possible to produce a magnesia-chromium based clinker with a small content.

When the pH is set to 11 to 12, the alkaline compounds such as lime in the above reaction solution are somewhat excessive, so before separating the formed precipitate mainly consisting of magnesium hydroxide from the reaction solution. Next, it is preferable to react this reaction solution with a decarbonated aqueous solution of seawater, bittern or brine to dissolve excess alkaline compounds such as lime. In this case, it is possible to obtain a precipitate of magnesium hydroxide which has a reduced content of calcium as well as boron.

Examples of the alkaline compound used in the above step include lime, dolomite a-fired products, and hydrates thereof.

According to the method of the present invention, the produced precipitate mainly consisting of magnesium hydroxide is separated using, for example, a thickener,
If necessary, it is washed with water, filtered, mixed with fine chromium ore powder, further press-molded, and then fired.

As the fine chromium ore powder, it is preferable to use, for example, a crushed natural ore containing at least about 30% by weight of chromium in terms of C, O8, and at most about 5% by weight of silicon in terms of SiO2. It is advantageously used as a fine powder with a particle size that can pass through a 44μ sieve.

Firing is usually performed at a temperature of 1800 to pH 00°C for about 15 minutes.
It will be held for 1 hour. Pressure forming is preferably carried out under a pressure of a2 to 2 tons/ell.

In order to facilitate understanding of the method of the present invention, preferred embodiments up to the formation of magnesium hydroxide precipitation in the present invention will be described as follows.

For example, an aqueous solution of ferrous sulfate is added to a decarbonated bath solution of seawater, and then lime is added to produce a reaction solution with a pH x L2 to IL8, and the weight ratio as oxides (chi) CαO/MQO is about 2 to 4 chi, SiO,/MgO about α05-α2% and Fg, 0. A precipitate mainly consisting of magnesium hydroxide with a concentration of about α2 to 3% /MtO is formed, and before separating this precipitate from the reaction solution, for example, decarbonated water of seawater is added to the reaction system to adjust the pH to 9.8 to 10. .8 and weight ratio as oxide (%) Ca 07 M g O approx. L8-40%,
S40. /MgO about α05~(L 25% Oyohi Fa, 0./MyO) A precipitate mainly consisting of magnesium hydroxide of about 0.2~3ts is formed, then washed with water as necessary, and the amount ratio of %)CaO
/MctO approx. L 4-1.8%, Sin, /MgO
Approximately (1,05~0.30 TokyohiFa!0./M
A precipitate consisting primarily of magnesium hydroxide with a QO of about .alpha.2-3 is formed.

Thus, according to the method of the present invention, it is possible to produce a high-density sintered magnesia-chromium clinker that cannot be obtained by conventional methods.

Thus, according to the method of the present invention, as described above, MgO62
% by weight or more, Cr, 0.30% by weight or less, and other oxides such as Cab, 540. , FatO3 and A
I, 0. A high density sintered magnesia-chromium based clinker having a chemical composition of 20% by weight or less can be provided. The clinker of the present invention preferably exhibits a chemical composition containing at least 65% by weight of MQO, more preferably at least 70% by weight.

Further, the clinker of the present invention has at least one
45 (1/an”, preferably 148g 10n”
.

More preferably, it has a high density of 3.50 g/cs''.

Furthermore, the clinker of the present invention contains the above-mentioned other oxides, for example, in an amount of 2 g of CaO or less, sio! 2% by weight or less,
FatO, 10% by weight or less and At.

It is preferred to indicate a chemical composition containing less than 0.036% by weight.

Hereinafter, the present invention will be explained in detail using examples, but the present invention is not limited in any way to the examples.

In addition, various physical property values in this book 8A#1 were measured by the following method.

Chemical composition Measured according to "JSPS 1 Chemical analysis method of Madanesian clinker" (x, s g', refer to 'x edition refractory notebook) determined by the Test Methods Subcommittee of the 124th Committee of the Japan Society for the Promotion of Science. did.

Especially B20. Regarding the analysis, the committee will consider and
The measurement was carried out using the curcumin method (absorption photometry) adopted as the Jakushin method.

“JSPS Method 2 Method for Measuring Apparent Porosity, Apparent Specific Gravity and Bulk Specific Gravity of Madanesia Clinker” (1981
(Refer to the 2015 Refractory Handbook) According to K, it was calculated using the following calculation formula.

island Bulk specific gravity=□×S W, -W.

117, : Dry weight of clinker Cy>W2 : Weight of sample saturated with white kerosene in white kerosene (g) W, : Weight of sample saturated with white kerosene (g) S : White kerosene at measurement temperature Specific gravity Crt1cm") [Example] Examples 1 to 4 FttS04 solution was added to decarboxylated seawater so that the ratio of Kg ions and F- ions was 0.4/100 in terms of Fe, 0./MgO weight. was added.

Purified Ca(OH) and milk were added to this seawater to produce a slurry mainly composed of Mrt(OBOt).

The pH of the reaction solution was IL7. The slurry thus produced was further washed with fresh water and filtered, and the resulting My(OH)t cake having the chemical composition shown in Table 1 was finely ground to a particle size of 44p or less. Chromium ore from New Caledonia / J
/ y (OR) The weight ratio of t is 10/9G based on the scorching heat standard.
, $10/80.30/70.4G/600 ratio.

Table 1 MgOCa0 54011azO, Al, 0 @ B, 0
．． Cr2O2 Further, each of the obtained mixtures was dried and f
After molding at a pressure of lto%/at'', 1950
A sintered mug black clinker was produced by firing at 30 minutes at ℃. The apparent porosity, bulk density, and chemical composition of the obtained clinker are shown in Table 2.

Examples 5 to 8 The M y (OH) 2 used in Examples 1 to 4 had the chemical composition shown in Table 3, and the South African chromium ore finely ground to a particle size of 44 μ or less was mixed with chromium ore/M
The weight ratio of rt(OK)t is 10/s o based on scorching heat,
They were mixed at a ratio of 2G/80.3G/7G and 4G/66.

Table 3 MgOCa0540pHg! 0@Al, 03E, 03
Cr, 0311709 view 0.96 f120 13
．． 32 α05 5LOO Furthermore, each of the obtained mixtures was dried and molded at a pressure of 2gO%/Country 2, and then 1
A sintered mug clinker was produced by firing at 950° C. for 30 minutes. The apparent porosity of the obtained clinker,
The bulk density and chemical composition are shown in Table 4.

Comparative Examples 1 to 4 Purified Cα(m) milk was added to decarboxylated seawater,
A Mrt (011)z slurry was produced. The pH of the reaction solution at this time was 10.5. After washing the generated slurry with fresh water and filtering it, the New Caledonian chromium ore used in Examples 1 to 4 was converted into chromium ore/Jf
The weight ratio of I <Of) 2 is 10/90 on a scorching basis.
They were mixed in a ratio of 20/80, 30/70, and 40/6G. Further, each of the obtained mixtures was dried for 2 t.
After molding at a pressure of 1,950°C and 30°C
A sintered mug/black clinker was produced by firing under conditions of 1 minute. The blind porosity, bulk density and chemical composition of the obtained clinker are shown in Table 5.

Comparative Examples 5-6 Decarboxylated seawater was purified to produce a 90a (0 liter, milk added, MyCoH)t slurry. The pH of the reaction solution at this time was 11.7. After washing the generated slurry with fresh water and filtering it, the New Caledonian chromium ore used in Examples 1 to 4 was mixed with chromium ore/M
y(OH'h weight ratio is 30/7G based on scorching heat, 4
They were mixed at a ratio of 0/800.

Furthermore, each of the obtained mixtures was dried to 2 ton/cm"
A sintered mug/black clinker was produced by molding at a pressure of 1,950° C. for 30 minutes. The apparent porosity, bulk density and chemical composition of the obtained clinker were
Shown in the table.

Claims (1)

[Scope of Claims] 1. Showing a chemical composition of 62% or more of MgO and 30% or less of Cr_2O_3 and 20% or less of other oxides, expressed in weight%, and having a high density of at least 3.45 g/cm^3 A high-density sintered magnesia-chromium clinker characterized by: 2. The other oxides mentioned above are CaO, SiO_2, Fe_
The clinker according to claim 1, containing at least 2O_3 and A1_2O_3. 3. The clinker according to claim 1 or 2, which has a chemical composition containing 65% by weight or more of MgO. 4. A clinker according to any one of claims 1 to 3 having a high density of at least 3.48 g/cm^3. 5. Adding water-soluble iron compounds to seawater, bittern or brine,
Dolomite ■ substantially simultaneously with or after said addition
It is characterized by adding calcination, lime or hydrates thereof to produce a precipitate mainly consisting of magnesium hydroxide, mixing the precipitate thus obtained with chromite powder, and calcination of the obtained mixture. A method for producing high-density sintered magnesia-chromium clinker. 6. The method according to claim 5, wherein a water-soluble iron compound is added to the precipitate consisting mainly of magnesium hydroxide in an amount amounting to 0.2 to 5% by weight on a scorching basis. 7. The precipitate mainly consisting of magnesium hydroxide was reduced to pH 1.
7. The method according to claim 5 or 6, wherein the compound is produced in one or more reaction solutions.