JP2008088044A - Monolithic refractory and waste melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chromium-free monolithic refractory which has resistance against melting loss as good as a Cr<SB>2</SB>O<SB>3</SB>-containing refractory and a waste melting furnace using the refractory as the lining for a waste melting furnace. <P>SOLUTION: The erosion-resistant monolithic refractory is obtained by adding 1-85 wt.% of a raw material of an (Mg, Ni)O solid solution and 5-85 wt.% of the total of MgO and NiO to a refractory raw material containing Al<SB>2</SB>O<SB>3</SB>-based material and MgAl<SB>2</SB>O<SB>4</SB>. The refractory obtained is useful for a monolithic refractory for a waste melting furnace. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a chromium-free amorphous refractory suitable for a waste melting furnace and a waste melting furnace using the chromium-free amorphous refractory.

  In recent years, the amount of municipal waste and waste generated has increased rapidly, and its disposal has become a major social problem. As a countermeasure, a melting method, that is, a volume reduction, detoxification, or recycling of waste is attracting attention. The melting method is a method of taking out inorganic substances in waste as molten slag and greatly reducing the volume.

The erosion speed of the refractory used in the melting furnace greatly depends on the composition and melting temperature of incinerated ash, fly ash, sewage sludge and the like. Although the composition of the molten slag varies greatly depending on the type of waste, in _general, SiO 2: 15 to 45 _{wt%, Al} 2 O 3: _10~20 wt%, CaO: 5 to 45 wt%, Na ₂ O1～15 _wt%, a K 2 O1~15 wt%, varies greatly by treatment equivalent to about 0.5 to 2.0 in basicity (C / S). In addition, incinerated ash and fly ash contain many harmful metals such as Cd, Pb, Zn, Cu, As, Cr, and Hg. Further, a large amount of S and Cl are contained as volatile components, and the melting temperature must be set to a high temperature of 1200 to 1650 ° C. Further, in a melting furnace where the temperature changes drastically, there is damage due to thermal shock.

Therefore currently, refractories consisting of _Al 2 _{O 3} and _Cr 2 _{O 3} as a refractory material containing _Cr 2 _{O 3} from corrosion resistance point is used. The higher the C ₂ O ₃ content, the better the corrosion resistance of the Cr ₂ O ₃ -containing refractory (see Patent Document 1). However, when the Cr ₂ O ₃ content is increased, the thermal shock resistance is reduced, and when Cr ₂ O ₃ in the refractory is used in a high-temperature and alkali-existing atmosphere, it changes to harmful hexavalent chromium. May cause contamination problems. Further, the higher the Cr ₂ O ₃ content, the greater the amount of hexavalent chromium produced.

Further, as refractories not containing Cr ₂ O ₃ , Al ₂ O ₃ —ZrO ₂ (see Patent Document 2), Al ₂ O ₃ —MgO (see Patent Document 3), Al ₂ O ₃ —SiC (Patent) Reference ₂ ) and Al ₂ O ₃ —NiO (see Patent Document 5) are known, but none of them shows sufficient durability as a refractory for melting furnaces with severe use conditions.
JP-A 63-30363 JP 2000-281455 A JP 2001-153321 A JP2000-203952 JP 2003-183082 A

Conventional chrome-free amorphous refractories are greatly inferior to chromium-containing products when used in a waste melting furnace. Since the slag of the waste melting furnace has many alkali components, Al ₂ O ₃ —ZrO ₂ or Al ₂ O ₃ —MgO is eluted with ZrO ₂ and MgO components in the slag, and is inferior in resistance to erosion. In addition, Al ₂ O ₃ —SiC is inferior in resistance to erosion because silicon carbide is oxidized in an oxidizing atmosphere of a waste melting furnace. In the case of Al ₂ O ₃ —NiO, it is possible to obtain only melt resistance of about 10% of Cr ₂ O ₃ .

The present invention provides, as a lining of a waste melting furnace, a chromium-free amorphous refractory having an excellent erosion resistance equivalent to a Cr ₂ O ₃ containing product and a waste melting furnace using the same for the lining. .

(1) By adding 1 to 85% by weight of a solid solution of (Mg, Ni) O to an amorphous refractory formed by adding a binder and a dispersant to a refractory raw material composition containing an Al ₂ O ₃ raw material As a result, a chromium-free amorphous refractory having excellent melt resistance was obtained. This is useful as a chromium-free amorphous refractory for waste melting furnaces. Moreover, even if other refractory components such as TiO ₂ and ZrO ₂ are included, the same effect is exhibited.

(2) By adding 1 to 85% by weight of a solid solution of (Mg, Ni) O to an amorphous refractory obtained by adding a binder and a dispersant to a refractory raw material composition containing MgAl ₂ O ₄ material As a result, a chromium-free amorphous refractory having excellent melt resistance was obtained. This is useful as a chromium-free amorphous refractory for waste melting furnaces. Moreover, even if other refractory components such as TiO ₂ and ZrO ₂ are included, the same effect is exhibited.

(3) An amorphous refractory material obtained by adding a binder and a dispersant to a refractory raw material composition containing an Al ₂ O ₃ raw material, including the two components MgO and NiO in the total composition, and the total amount of the chemical components By making the content of 5 to 85% by weight, a chromium-free amorphous refractory having excellent melt resistance was obtained. This is useful as a chromium-free amorphous refractory for waste melting furnaces. Moreover, even if other refractory components such as TiO ₂ and Zr ₂ are included, the same effect is exhibited.

(4) An amorphous refractory material obtained by adding a binder and a dispersant to a refractory raw material composition containing MgAl ₂ O ₄ raw material, including two components of MgO and NiO in the total composition, and the total amount of the chemical components By making the content of 5 to 85% by weight, a chromium-free amorphous refractory having excellent melt resistance was obtained. This is useful as a chromium-free amorphous refractory for waste melting furnaces. Moreover, even if other refractory components such as TiO ₂ and ZrO ₂ are included, the same effect is exhibited.

  Waste melting furnace used for at least a part of the furnace by casting or precasting the chromium-free amorphous refractory for waste melting furnace according to any one of items (1) to (4) .

The refractory of the present invention is a chromium-free amorphous refractory that does not contain Cr ₂ O ₃ component, and exhibits sufficient resistance to erosion under severe use conditions such as high alkali slag and high temperature operation unique to waste melting furnaces. . As a result, the chromium-free amorphous refractory of the present invention improves the operating rate of the melting furnace and the refractory unit by extending the life of the refractory, and solves the environmental pollution problem caused by hexavalent chromium generated after use.

By adding 1 to 85% by weight of a solid solution of (Mg, Ni) O to an amorphous refractory obtained by adding a binder and a dispersant to a refractory raw material composition containing an Al ₂ O ₃ raw material, Cr ₂ O Excellent corrosion resistance equivalent to ₃ containing products can be obtained.

By adding 1 to 85% by weight of a solid solution of (Mg, Ni) O to an amorphous refractory obtained by adding a binder and a dispersant to a refractory raw material composition containing a MgAl ₂ O ₄ material, Cr ₂ O Excellent corrosion resistance equivalent to ₃ containing products can be obtained.

An amorphous refractory formed by adding a binder and a dispersant to a refractory raw material composition containing an Al ₂ O ₃ raw material, including two components of MgO and NiO in the entire composition, and the total amount of the chemical components is 5 to By setting it to 85% by weight, excellent corrosion resistance equivalent to a Cr ₂ O ₃ -containing product can be obtained by generating a solid solution of (Mg, Ni) O during use in a waste melting furnace.

An amorphous refractory material obtained by adding a binder and a dispersant to a refractory raw material composition containing MgAl ₂ O ₄ -based raw material, including two components of MgO and NiO in the entire composition, and the total amount of the chemical components is 5 to By setting it to 85% by weight, excellent corrosion resistance equivalent to a Cr ₂ O ₃ -containing product can be obtained by generating a solid solution of (Mg, Ni) O during use in a waste melting furnace.

  The NiO in the (Mg, Ni) 0 solid solution in the present invention is preferably 10% by weight or more. When the NiO component is less than 10% by weight, excellent melt resistance cannot be expected.

  In the present invention, as a solid solution of (Mg, Ni) O to be used, a sintered (Mg, Ni) O solid solution obtained by firing MgO and NiO, and a melt (Mg, Ni) obtained by melting MgO and NiO ) There is O solid solution. When a molten (Mg, Ni) O solid solution is used, the greatest effect is obtained.

  In the present invention, the solid solution of (Mg, Ni) O used preferably has a porosity of 5% or less.

  The NiO component purity of the NiO raw material in the present invention is preferably 99% by weight or more.

  The MgO component purity of the MgO raw material in the present invention is preferably 99% by weight or more.

  The NiO-containing raw material is preferably used as fine particles having an average particle size of 45 μm or less.

In the present invention, MgO ingredient 28% MgAl ₂ O ₄ feedstocks used are theoretical composition, but close to _Al 2 _{O 3} component 72% is most desirable, the component ratio of the MgO component and _Al 2 _{O 3} component changed Use of spinel particles is also effective.

In the present invention, as MgAl ₂ O ₄ feedstocks used, _Al 2 _{O 3} and sintering MgAl ₂ O ₄ feedstocks obtained MgO was calcined, molten MgAl obtained by melting _Al 2 _{O 3} and MgO _{There are 2} O ₄ quality raw materials. When a molten MgAl ₂ O ₄ material is used, the greatest effect is obtained.

  In the present invention, the addition amount of the (Mg, Ni) O solid solution is about 50% by weight, and the most excellent resistance to erosion can be obtained. Even if it is added up to 70% by weight, it does not change the resistance to melting with the 50% by weight added product. When it exceeds 70% by weight, the resistance to melting loss is inferior to that of the 70% by weight added product.

  The amorphous refractory according to the present invention contains two components of MgO and NiO in the entire composition, and the most excellent resistance to erosion can be obtained when the total amount of the chemical components is about 50% by weight. Excellent resistance to erosion can be obtained when the total amount of chemical components is up to 70% by weight. In the case where the total amount of chemical components is 70% by weight and 50% by weight, there is no change in the resistance to melting. When the total amount of the chemical components exceeds 70% by weight, the melt resistance is inferior to that of itself.

  As long as it does not inhibit the effect of the present invention, it may be used as a refractory raw material, further one or more selected from silica, mullite, dolomite, calcia, zircon, zirconia, titania, silicon carbide, carbon, yttria, etc. Good.

The amorphous refractory according to the present invention does not substantially contain Cr ₂ O ₃ in order to prevent environmental pollution. Here, the term “substantially free” means, for example, 0.1% by weight or less of impurities or MgO-based raw material as an anti-digestive amount even if Cr ₂ O ₃ is contained.

  As a technical common sense for the workability of the amorphous refractory, a binder and a dispersant are added. However, these materials and addition amounts are not particularly different from conventional ones. The binder may be used alone or in combination of two or more selected from alumina cement, magnesia cement, Portland cement, hydraulic alumina, aluminum oxycarboxylate, phosphate, silicate, silica sol, phenol resin, and the like. Among these, alumina cement imparted with construction body strength and heat resistance is preferable. The addition of the binder is an outer coating with respect to 100% by weight of the refractory raw material composition, and preferably 1 to 15% by weight.

  The dispersant has the effect of imparting fluidity during construction of the irregular refractory. Various materials for the dispersant have been proposed. The type of the dispersant in the present invention is not limited, but includes sodium tripolyphosphate, sodium hexametaphosphate, acidic hexametaphosphate soda, ultrapolyphosphate soda, sodium citrate, sodium borate, sodium tartrate, carboxyl group-containing polyether Polyacrylic acid soda, polycarboxylic acid soda, sulfonic acid soda, lignin sulfonic acid soda, and the like.

  The addition amount of the dispersant is preferably 0.01 to 1% by weight as an outer coating with respect to 100% by weight of the refractory raw material.

  In addition to the above, the amorphous refractory of the present invention may contain a curing regulator, aluminum lactate, organic fiber, metal, glass and the like as necessary. These addition amounts are desirably 5% by weight or less as an outer coating with respect to 100% by weight of the refractory raw material composition.

  In the construction, about 2 to 8% by weight of water is added and kneaded with the outer coating for the entire blended composition described above, and cast using a mold. When pouring, filling is performed by applying vibration. Curing and drying after construction. This construction may be performed by pouring directly into the furnace, or may be lined by a pre-mold method using a pre-molded product obtained by pouring into a mold at another location.

  Tables 1 and 2 show the chemical components of the raw materials used.

  Tables 3 to 7 show comparative examples of the present invention, and further show the test results of each example.

  Tables 8 to 16 show examples of the present invention, and further show test results of the examples.

  The evaluation method of corrosion resistance is as follows.

  An erosion test at 1500 ° C. for 24 hours was performed by the rotary erosion drum method under the condition of a slag having a basicity of 1.0, and the total value (mm) of the erosion amount was shown from both original dimensions.

  Comparative Example 1 to Comparative Example 4 are greatly inferior in resistance to melting as compared with Comparative Example 5 which is a chromium oxide-containing product.

  In Comparative Examples 6 to 9 in which the (Mg, Ni) O solid solution is added to Comparative Example 1, no significant improvement in resistance to melting loss is observed.

  Even in Comparative Example 10 in which 1% by weight of theoretical spinel is added to Comparative Example 7, no significant improvement in the erosion resistance is observed.

  In Examples 26 to 30, the added amount of the (Mg, Ni) O solid solution is 70% by weight or more, but the added amount of the (Mg, Ni) O solid solution in the example is 70% by weight. As a result, the melt resistance was inferior to that of Example 5, Example 10, and Example 20.

  Comparative Example 11 to Comparative Example 15 contain magnesium oxide and nickel oxide in the refractory, and the total amount of the chemical composition is 5% by weight or less. It is not allowed.

  Examples 46 to 50 include magnesium oxide and nickel oxide in the refractory and the total amount of the chemical composition is 70% by weight or more. Magnesium oxide and nickel oxide are contained in the refractory in the example. In addition, the corrosion resistance was inferior to those of Examples 45 and 55 in which the total amount of the chemical composition was about 70% by weight.

  In Examples 1 to 5, (Mg, Ni) O-5 was added to Comparative Example 1. As the amount of addition increases, the resistance to erosion improves. When the addition amount is around 50% by weight, the corrosion resistance is the best, and the addition amount is almost parallel up to 70% by weight.

  Examples 6 to 10 are obtained by adding (Mg, Ni) O-10c to Comparative Example 1. As the amount of addition increases, the resistance to erosion improves. When the addition amount is around 50% by weight, the corrosion resistance is the best, and the addition amount is almost parallel up to 70% by weight.

  In Examples 11 to 15, (Mg, Ni) O-10c of Examples 6 to 10 is changed to (Mg, Ni) O-10b which is a molten product. Even when the (Mg, Ni) O solid solution having the same composition was used, the use of a molten product showed the most excellent resistance to erosion. In addition, as the amount added increases, the resistance to erosion improves. When the addition amount is around 50% by weight, the corrosion resistance is the best, and the addition amount is almost parallel up to 70% by weight.

  Examples 16 to 20 are obtained by adding (Mg, Ni) O-20 to Comparative Example 1. As the amount of addition increases, the resistance to erosion improves. When the addition amount is around 50% by weight, the corrosion resistance is the best, and the addition amount is almost parallel up to 70% by weight.

In Examples 21 to 25, MgO—NiO—TiO ₂ was added to Comparative Example 1. As the amount of addition increases, the resistance to erosion improves. When the addition amount is around 50% by weight, the corrosion resistance is the best, and the addition amount is almost parallel up to 70% by weight. The difference from Example 6 to Example 10 is that TiO ₂ is included as another refractory component. The deterioration of the melt resistance due to the inclusion of TiO ₂ is not recognized.

  In Example 7 and Example 31, the porosity of the added (Mg, Ni) O-10 is 3% in Example 7, whereas in Example 31, the porosity is 15%. Due to this difference, Example 7 showed better melt resistance. From this, it can be seen that the smaller the porosity of the (Mg, Ni) O solid solution added, the better.

  Examples 32 to 35 are obtained by adding theoretical spinel to Example 7. As the amount of theoretical spinel added increases, the erosion resistance improves.

  In Example 36 and Example 37, the average particle diameter of the added nickel oxide is 45 μm or less in Example 36, whereas it is larger than 45 μm in Example 37. Due to this difference, Example 36 showed superior resistance to melting damage. From this, it is understood that the smaller the average particle diameter of the nickel oxide to be added, the better.

  In Examples 41 to 45, the total amount of two components of magnesium oxide and nickel oxide is added to Comparative Example 1 in an amount of 5% by weight or more. As the amount of addition increases, the resistance to erosion improves. When the total addition amount is around 50% by weight, the resistance to erosion is most excellent, and the total addition amount is almost parallel to 70% by weight.

  In Example 43 and Example 51, the average particle diameter of the added nickel oxide is 45 μm or less in Example 43, whereas it is larger than 45 μm in Example 51. Due to this difference, Example 43 showed better melt resistance. From this, it is understood that the smaller the average particle diameter of the nickel oxide to be added, the better.

  In Examples 52 to 54, the molten alumina of Examples 42 to 44 is changed to a theoretical spinel. From this result, it can be seen that changing molten alumina to theoretical spinel leads to further improvement in resistance to melting.

  In both cases, MgO and NiO-added products showed excellent results. Above all, when the amount of MgO + NiO was 35% by weight or more, the slag erosion resistance was equal to or more than that of 20% by weight of chromium oxide.

  When the amorphous refractory having the composition shown in Example 9 was used at the gate of the fly ash melting furnace, 170 days in Comparative Example 5 yielded high durability of 180 days or more.

The invention's effect

  Chromium-free amorphous refractories combined with magnesium oxide and nickel oxide showed excellent slag erosion resistance by making magnesium oxide and nickel oxide solid solution. Moreover, even if the raw materials already prepared as magnesium oxide and nickel oxide solid solution are added, the same excellent slag erosion resistance is exhibited. This limits the use of chromium oxide-containing refractories and can alleviate the problem of hexavalent chromium.

Claims (5)

A chrome-free amorphous refractory for a waste melting furnace, characterized in that the composition of the refractory material is mainly composed of three chemical components of Al ₂ O ₃ , MgO and NiO.   A chromium-free amorphous refractory for a waste melting furnace characterized by containing 1 to 85% by weight of a solid solution of (Mg, Ni) O in the refractory raw material composition.   A chrome-free amorphous refractory for waste melting furnaces that produces (Mg, Ni) O solid solution during use of large materials in waste melting furnaces.   A chromium-free amorphous refractory for a waste melting furnace, characterized in that the refractory raw material composition contains two components of MgO and NiO, and the total amount of chemical components of the refractory is 5 to 85% by weight.   The waste melting furnace which used the chromium free amorphous refractory for waste melting furnaces of any one of Claims 1 thru | or 4 for at least one part of the furnace by pouring construction or precast construction.