JPH04952B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a monolithic refractory composition used in various industrial kilns for non-ferrous metals, ceramics, etc., as well as various steel kilns. [Prior Art] Monolithic refractories are generally constructed by mixing a powdered material with water or an aqueous binder solution. However, monolithic refractories containing basic components such as MgO and CaO undergo hydration reactions when mixed with water.
It often undergoes the so-called digestive phenomenon, cracking or collapsing during curing or drying. In order to suppress such defects, refractories containing basic aggregates are disclosed in Japanese Patent Application Laid-Open No. 52-32908, Japanese Patent Application Laid-Open No. 113812-1982, Japanese Patent Application Laid-Open No. 129864-1987,
There is a method using additives disclosed in JP-A-58-99177. [Problems to be Solved by the Invention] However, all of the additives disclosed in the above-mentioned publications exhibit sufficiently satisfactory performance in terms of the digestion suppressing effect and the construction work as a monolithic refractory. It's hard to say. That is, JP-A No. 52-32908 and JP-A No. 53-113812 both disclose digestive inhibitors made of organic substances, but the former is an additive that also has a binder effect during the production of firebrick. Although it is effective when mixed with aggregate as an aqueous solution and then pressure-molded, the concentration of the aqueous solution is high for pouring materials, etc., making it difficult to use. In the case of the latter, it is mainly effective for slinger materials, etc., but it is not sufficiently effective for pouring materials, coating materials, spraying materials, etc., and if used in large quantities, the strength of the construction object will decrease, which is undesirable. On the other hand, JP-A-57-129864 and JP-A-58-
Publication No. 99177 discloses an inorganic digestive inhibitor, but the former is highly effective in drying in an aqueous solution and in a low temperature range, but is not effective in drying under conditions that produce an autoclave state of 100°C or higher. not enough. The latter includes silica flour, etc., which are commonly used in pouring materials and coating materials, but when added in small amounts, the effect is poor, and when used in large amounts, the corrosion resistance of the basic aggregate decreases, which is undesirable. [Means for Solving the Problems] The present invention was made in view of the above-mentioned circumstances, and its purpose is to provide excellent construction workability and to eliminate water or steam during construction, curing, and drying processes. An object of the present invention is to provide an amorphous refractory composition comprising a basic raw aggregate that does not cause cracking or collapse phenomena accompanying hydration reactions in a refractory molded article. Conventionally, phosphoric acid, water-soluble aluminum phosphate, or the like has been used as a binder for refractories that do not contain basic aggregate. However, these binders have not been put to practical use in monolithic refractories containing basic aggregates. However, the present inventors focused on the reactivity of such basic aggregates with phosphoric acid, etc., and created a slow reaction rather than a rapid reaction, and did not react with the basic aggregate as a whole. As a result of various studies on methods for stabilizing basic aggregates and suppressing the digestion phenomenon by reacting only on the particle surface of basic aggregates or only with basic ions dissolved in water, the present invention was arrived at. That is, the present invention provides an amorphous refractory made of one or more of magnesia clinker, spinel clinker, magnesia-chromium clinker, dolomite clinker, and lime clinker, and cations such as aluminum, chromium, iron, magnesium, calcium, potassium,
Contains one or more of lithium, boron, zinc, lead, barium, bismuth, and silver, and is insoluble in water or has a solubility of 2.5 in water below 40°C
A monolithic refractory composition characterized in that 0.02 to 20 parts by weight of a phosphate which is hardly soluble in g/100ml or less and whose water suspension is acidic is added to 100 parts by weight of the total amount of the clinker. It is a thing. Magnesia clinker, spinel clinker, magnesia-chrome clinker used in the present invention,
Dolomite clinker and lime clinker are commercially available in various grades such as seawater magnesium shea clinker, natural magnesia clinker, fused magnesia clinker, sintered spinel clinker,
Electrofused spinel clinker, natural dolomite clinker, synthetic dolomite clinker, sintered lime clinker, fused lime clinker, etc. can be used. Preferably, it is a pulverizable lump or one classified into various particle sizes so that the particle size constituting the refractory composition can be freely selected. These clinkers may be used alone or in combination of two or more. The phosphate used in the present invention is insoluble in water or has a solubility of 2.5 g/100 ml in water below 40°C.
It is poorly soluble and exhibits acidity in water suspension. If the solubility in low-temperature water is high, the reaction with basic aggregate will proceed rapidly during kneading with water or during construction, causing coagulation, etc., making construction difficult. Furthermore, if the PH in the suspended state is alkaline, the digestive suppressive effect is poor. The above water-insoluble or sparingly soluble phosphates,
It has an orthophosphate group or a condensed phosphate group, and contains aluminum, chromium, magnesium, calcium,
Those that form salts with potassium, lithium, boron, zinc, lead, barium, bismuth, silver, etc. are applicable. For example, in the case of aluminum phosphate,
Among the orthophosphoric acid groups, Al(H ₂ PO ₄ ) ₃ is water-soluble, but AlH ₃ (PO ₄ ) ₂ , Al ₂ (HPO ₄ ) ₃ and
AlPO ₄ is insoluble in water and can be used in the present invention.
AlPO ₄ etc. have various crystal forms including amorphous, and any of them may be used. Condensed phosphates such as aluminum metaphosphate and aluminum tripolyphosphate are also sparingly soluble and can be used. Salts other than aluminum can be considered in the same way, and salts in which two or more salts are combined or form a solid solution can also be used. The amount of water-insoluble or sparingly soluble phosphate added varies depending on the type and blending ratio of the clinker used. That is, for magnesia chromium clinker, which is relatively stable against water, and alumina-rich spinel clinker, an effect can be seen with a very small amount of addition, but for magnesia-rich spinel clinker and magnesia clinker, the amount added will increase somewhat. Dolomite clinker and lime clinker, which contain a large amount of CaO and are active in water, need to be added in even larger amounts. Of course, the amount added also changes depending on the crystal state and crystal size of MgO and CaO in each clinker. Further, when each clinker is blended in various proportions, the amount added should be determined according to each blending proportion. In any case, 0.02 to 100 parts by weight of each clinker
Add in an amount of 20 parts by weight. If less than 0.02 parts by weight is added, cracks may occur in an autoclave during rapid drying, and if more than 20 parts by weight is added, the effect will not be high and it will be uneconomical. The monolithic refractory composition of the present invention may contain cements, inorganic binders such as sodium silicate, water-soluble sodium phosphate, and various resins, as well as those used in conventional general monolithic refractories. It is possible to use organic binders such as, dispersants such as various water-soluble sodium phosphates and carboxylates, hardening modifiers such as various sulfates, carbonates, hydroxides, chlorides, borides, carboxylic acids, etc. can. However, the amorphous fireproof composition of the present invention does not necessarily require a binder, especially when performing pouring construction. This is because the pH increases due to Mg and Ca ions eluted from the clinker, which causes a trace amount of phosphoric acid to elute and gradually form compounds with Mg ²⁺ and Ca ²⁺ , strengthening the construction structure. This is thought to be due to the The particle size structure of the refractory composition of the present invention includes pouring, pouring,
It is possible to provide aggregate particle size composition suitable for construction methods such as spraying, patching, coating, and ramming, and if necessary, clay or silica fine powder can be used to improve properties such as fluidity and viscosity. , alumina fine powder, etc. may be added. [Function] Since the monolithic refractory composition of the present invention contains a phosphate salt that is insoluble or sparingly soluble in water, it is stable in water, and hardly reacts when the monolithic refractory composition is mixed with water and applied. However, as time passes after water is added, the pH of the water increases due to Mg ²⁺ and Ca ²⁺ ions eluted from each clinker, and a trace amount of phosphoric acid component elutes, causing Mg ²⁺ and Ca ions to elute. It is thought that it forms a compound with ²⁺ and does not cause cracks or collapse due to digestion phenomena. [Example] Example 1 A blend was prepared in the proportions shown in Table 1, and the blend
Add 6.5 parts by weight of water to 100 parts by weight, and after kneading 40 parts by weight
It was poured into a shape of 40 x 160 mm, left to cure at room temperature for 24 hours, and used as a sample. After drying samples of each formulation at 110°C for 24 hours,
The bending strength and porosity were measured. Immediately after curing, another sample was subjected to an autoclave test under conditions of 5 atm x 3 hours. Bending strength and porosity were measured for the samples that did not disintegrate after the autoclave test. The results are shown in Table 1. As is clear from Table 1, the formulation according to the present invention shows no cracking or disintegration even under severe conditions of 5 atm x 3 hours. Furthermore, the flexural strength of the formulations according to the invention after the autoclave test is increased compared to the dried sample, and the porosity is also reduced. On the other hand, the comparative example collapsed in the autoclave test and showed a decrease in strength, and Al(H ₂ PO ₄ ) ₃
With water-soluble and acidic phosphates such as phosphates, a reaction occurred during kneading, making it impossible to apply the method.

【table】

[Table] Example 2 Compounds were prepared in the proportions shown in Table 2, water was added according to each construction method, and after kneading the mixture was 230×230×
After molding into 300mm blocks and curing at room temperature for 24 hours,
Drying was performed at 110°C for 3 hours and then at 200°C for 24 hours, and the appearance after drying was observed. This type of drying test for large blocks is a practical method for determining the extent of defects that occur during drying in an actual furnace, since the internal vapor pressure is not constant due to differences in the air permeability of the construction body. As shown in Table 2, all of the comparative examples cracked or collapsed after drying, but the composition of the present invention had good workability and showed no change at all after drying.

【table】

[Table] *Water of polysorbit solution [Effect of the invention] The present invention improves workability during construction by adding a phosphate that is insoluble or sparingly soluble in water to an amorphous fireproof composition made of basic aggregate. In other words, it is possible to obtain a construction body that has excellent fluidity, viscosity, filling properties, etc., and does not generate cracks or collapse due to the hydration reaction of the basic aggregate during construction, curing, and drying. Slinger material, spray material,
It can be applied to any construction method such as coating material or ramming.

Claims (1)

[Claims] 1 One or two of magnesia clinker, spinel clinker, magnesia-chromium clinker, dolomite clinker, and lime clinker
In monolithic refractories consisting of more than 1 species, cations include aluminum, chromium, iron, magnesium,
Contains one or more of calcium, potassium, lithium, boron, zinc, lead, barium, bismuth, and silver, and is insoluble in water or poorly soluble with a solubility of 2.5 g/100 ml or less in water at 40°C or lower. , and a phosphate whose water suspension is acidic, per 100 parts by weight of the clinker.
A monolithic refractory composition characterized in that 0.02 to 20 parts by weight is added.