JP6366953B2 - Casting method for irregular refractories - Google Patents

Description

  The present invention relates to a method for casting an irregular refractory.

  Curing troubles such as curing during the construction and curing delay are known as problems when pouring in an irregular refractory. The cause of this curing trouble is that the pot life is affected by the temperature during construction. The pot life refers to the time from when the raw material mixture and water are kneaded until the plasticity is lost.

  Therefore, the pot life is adjusted by using a curing regulator (for example, Patent Document 1). For example, since there is a concern that the temperature will be high and the material will harden quickly in summer, a curing retarder is added. On the other hand, since there is a concern that the temperature is low in winter and the material does not cure within a predetermined time, a curing accelerator is added.

  However, even if a curing modifier is used, stable construction may not be possible depending on changes in environmental conditions. For example, if a sudden temperature change occurs and the temperature differs greatly from the temperature at the time of shipment verification, there will be a difference between the pot life set at the time of shipment and the pot life at the time of construction. There is. There is also a problem that a slight trouble in the addition amount of the curing regulator causes a curing trouble and prevents stable construction.

  In addition, the construction of the amorphous refractory is performed through a curing process and a drying process. In the curing process, if the curing strength can be expressed in a short time, the time to the drying process can be shortened. For this reason, in a curing process, there existed a request to express curing intensity in a short time.

JP-A-9-76056

  The problem to be solved by the present invention is to provide a method for casting an amorphous refractory that can solve curing troubles and can develop curing strength in a short time.

  The present inventor prevents curing during construction by adjusting the addition amount of the curing regulator so that the pot life is sufficiently longer than the casting construction time, and performs microwave irradiation during curing. Thus, it has been found that if curing delay due to longer pot life is prevented, curing trouble can be solved and curing strength can be expressed in a short time.

  That is, according to one aspect of the present invention, in the casting method of the amorphous refractory obtained by kneading the raw material mixture and water, the casting construction is performed when the temperature of the amorphous refractory after kneading is 35 ° C. A casting process in which an amorphous refractory to which a curing modifier is added so as to have a pot life of more than twice the time is poured into the construction area, and microwaves are irradiated to the irregular refractory poured in by the casting process. And a curing process for curing, and a method for casting an irregular refractory is provided.

  In the present invention, when the temperature of the amorphous refractory after the kneading is 35 ° C., the casting is performed using the amorphous refractory to which a curing regulator is added so that the pot life is more than twice the casting construction time. I do. By securing a sufficiently long pot life with respect to the pouring construction time in this way, even if environmental conditions such as the outside temperature change, the amorphous refractory hardens during the pouring construction (in the middle of the pouring work). Can be prevented in advance.

  For example, in summer, the temperature of the irregular refractory may be 35 ° C. or higher. At this time, as the temperature rises, there is a concern that the amorphous refractory is poured and hardened during the construction. On the other hand, when the temperature of the amorphous refractory is 35 ° C., the pot life is sufficiently longer than the pouring work time if the pot life is more than twice the pouring work time. For this reason, the trouble of hardening of the irregular refractory during the pouring work can be prevented in the summer. Then, by irradiating microwaves to the cast amorphous refractory, the amorphous refractory can be cured at a temperature higher than the temperature of the amorphous refractory in summer, and in case of natural curing or warm air curing In comparison, the curing strength appears in a short time.

  On the other hand, in the winter, the temperature of the amorphous refractory is lower than in the summer. In the present invention, when the temperature of the amorphous refractory is 35 ° C., the curing regulator is added so that the working time is more than twice the casting construction time. It will grow further. Even in such a case, the curing intensity is expressed in a short time by irradiating the microwave as compared with the case of natural curing or warm air curing.

  That is, according to the construction method of the present invention, the curing strength can be expressed in a short time without causing a curing trouble even in summer or winter. Thereby, the time to a drying process can be shortened.

  Regardless of the outside temperature, the amount of curing modifier is adjusted so that the pot life is sufficiently long with respect to the pouring time. Trouble can be prevented. Moreover, since it is not necessary to delicately adjust the addition amount of the curing modifier, it is possible to prevent the occurrence of curing troubles due to the variation in the addition amount.

  Furthermore, by curing using microwaves, it is possible to increase the temperature to the back of the material in a short time compared to curing with warm air such as a burner, and the input energy is directly Since it is absorbed by the material, it is energy efficient and effective in reducing costs.

  The amorphous refractory used in the present invention is obtained by kneading a raw material blend and water as in the conventional case. The raw material blend is mainly composed of a refractory raw material, and typically contains a binder and a dispersant. Furthermore, in the present invention, a curing modifier is added in order to adjust the pot life of the irregular refractory. The curing modifier may be blended in advance with the raw material blend, or may be added when kneading with water. In addition, a hardening regulator is a general term for a hardening accelerator and a hardening retarder.

  As these refractory raw materials, binders, dispersants, and curing modifiers, those generally used for conventional amorphous refractories for pouring can be used.

  For example, examples of the refractory raw material include alumina, silica, magnesia, calcia, silicon carbide, carbon, spinel, clay, and the like, and those obtained by combining two or more of these also correspond to this.

  Examples of the binder include alumina cement, phosphate, silicate, chloride, sulfide, hydroxide, silica sol, and alumina sol.

  Examples of the dispersant include sodium tripolyphosphate, sodium hexametaphosphate, polyacrylic acid, sodium polyacrylate, sodium polyacrylate, polycarboxylic acid, sodium naphthalene sulfonate, sodium lignin sulfonate, and the like.

  Among the curing modifiers, examples of the curing accelerator include lithium carbonate, lithium hydroxide, lithium chloride, lithium citrate, sodium hydroxide, potassium hydroxide and the like. Curing retarders include boric acid, borax, pyrophosphoric acid, metaphosphoric acid, tripolyphosphoric acid, hexametaphosphoric acid, ultrapyrophosphoric acid, ultratripolyphosphoric acid and their sodium and potassium salts, citric acid, tartaric acid, gluconic acid and their sodium. Examples include salts and potassium salts.

  In the present invention, when the temperature of the amorphous refractory after kneading is 35 ° C., the curing regulator is added so that the pot life is twice or more the casting construction time. If the pot life is less than twice the casting time, if a sudden temperature change occurs, curing problems may occur. Therefore, it is necessary that the addition amount of the curing modifier is a pot life that is at least twice as long as the casting time. The pot life is not particularly limited as long as it is at least twice as long as the casting time. This is because the curing strength can be expressed in a short time by irradiating the microwave if the pot life is more than twice the casting construction time. The inventor has confirmed that no problem arises with a pot life of at least 20 times the casting construction time.

  Here, in the present invention, the “pouring time” means that the amorphous refractory after kneading after the raw material mixture is charged into the kneading machine (mixer), after the addition of water and the kneading operation, has a predetermined shape. It is the time from pouring into the frame and finishing applying vibration to the poured amorphous refractory. When kneading is performed in multiple steps, that is, when there are multiple kneading batches, vibration is applied to the irregular refractory in the last kneading batch from the time when the first kneading batch is put into the kneading mixer. It means the time to finish.

The “pot life” is the time from the end of kneading of the irregular refractory (when there are multiple kneading batches, the end of kneading for each kneading batch) until the amorphous refractory loses its plasticity. Means the time until the penetration value of the push cone becomes 24 mm or more when the amorphous refractory is penetrated by the push cone based on JHS A601 “Soil Hardness Test Method”.

  In the present invention, the amorphous refractory poured into the frame (construction area) is cured by irradiation with microwaves. Conventionally, the microwave irradiation to the amorphous refractory is performed in the drying process after the curing process (see, for example, JP-A-2005-194110), and the microwave irradiation is not performed in the curing process. However, since the technique itself for irradiating the amorphous refractory with microwaves is known, a microwave irradiation method and irradiation conditions suitable for the curing process are set with reference to this known technique.

  Examples and Comparative Examples of the present invention will be described with reference to Tables 1 and 2.

  In the examples and comparative examples, the refractory raw material of alumina-magnesia shown in Table 1 was used. Then, a binder, a dispersant, and a curing modifier were added to the refractory raw material to obtain a raw material blend. Alumina cement was used as a binder, polyacrylic acid was used as a dispersant, and sodium silicofluoride was used as a curing retarder.

  For irregular refractories using the raw material blends of Examples and Comparative Examples, casting construction time (h), pot life (h) when the temperature of the irregular refractory after kneading is 35 ° C., casting construction Table 2 shows the pot life (magnification) with respect to time, the temperature of the amorphous refractory after kneading, the curing method, the curing time after construction, the presence or absence of curing trouble, and the overall evaluation.

  The construction of the irregular refractories in the examples and comparative examples is a construction that assumes a construction amount of about several tons and requires one hour as a casting construction time.

  The casting construction time takes longer as the construction amount is larger, but the pot life is constant regardless of the construction amount. Therefore, the pot life in the examples and comparative examples was evaluated in the following manner using raw materials of the same lot as the raw materials used for the construction with a construction amount of several tons.

  The raw material composition of the same rod as the raw material composition used for construction of several tons is kneaded at a water temperature of 35 ° C., and the kneaded material is poured into a metal frame of 40 mm × 40 mm × 160 mm, and the JHS A601 “ It measured based on the soil hardness test method. In this measurement, when the sample is not strong and soft, the penetration value cannot be measured, and the penetration value increases as the strength of the sample develops. Specifically, when the sample was penetrated with a push cone, the time until the penetration value of the push cone reached 24 mm was defined as the pot life. The adjustment of the pot life in Examples and Comparative Examples was performed by appropriately changing the addition amount of the curing retarder. The pot life may be adjusted by using a curing accelerator and a curing retarder in combination.

  The pot life with respect to the pouring construction time is indicated by the magnification with respect to the pouring construction time (1 hour) as measured by the above method.

  Regarding the curing method, the microwave curing was performed by placing a sample in a microwave device and irradiating the material with microwaves at a constant output.

  Natural curing was performed by placing a sample in a constant temperature incubator. The warm air curing was performed by placing a sample in a thermostat and applying warm air to the sample.

  The temperature of the amorphous refractory after kneading was measured with a thermometer on the surface of the amorphous refractory.

  The curing time after construction is the time required to obtain the strength required for drying. The curing time after the construction was the time until the penetration value of the push cone reached 35 mm when the surface of the construction body was penetrated with the push cone based on JHS A601 “Soil Hardness Test Method”.

  In the curing process, if the curing strength can be expressed in a short time, the time to the drying process can be shortened. Therefore, the shorter the curing time after construction, the better. About an Example and a comparative example, relative evaluation was carried out in order of (circle), (triangle | delta), and x in order with the short curing time after construction. Specifically, a curing time of less than 2 hours was indicated as ◯, 2 to 4 hours as Δ, and over 4 hours as X.

  Hardening trouble shows hardening in the middle of construction, or hardening delay.

Comprehensive evaluation evaluated in three steps, (circle), (triangle | delta), and x. The evaluation criteria are as follows.
○: Curing time after construction is ○ and there is no curing trouble △: Curing time after construction is △ and there is no curing trouble ×: Curing time after construction × Or if there is a curing problem

  In the comprehensive evaluation, “◯” was accepted, and Δ and “x” were rejected.

  As shown in Table 2, the comprehensive evaluation of Examples 1 to 8 within the scope of the present invention was good with good. In contrast, in Comparative Examples 1 to 7, the overall evaluation was x.

  Comparative Examples 1 to 3 are examples in which the pot life (measured at 35 ° C.) is 1.2 times the casting construction time. In Comparative Example 1, the temperature after kneading at the time of actual construction was 5 ° C., and the curing method was natural curing, so that the curing time after the construction was long and a delay in curing occurred. Although the comparative example 2 did not generate | occur | produce the hardening trouble, the curing time after construction became long compared with the case of microwave curing. In Comparative Example 3, since the temperature after kneading at the time of actual construction was 40 ° C., the working time at the time of construction was shorter than the working time measured at 35 ° C., and the material was cured during the construction. Trouble occurred.

  Comparative Examples 4 and 5 are examples in which the pot life was doubled with respect to the casting construction time and natural curing was performed. The longer the pot life, the longer the curing time after construction, causing a delay in curing.

  Comparative Examples 6 and 7 are examples in which the pot life was doubled with respect to the casting construction time and the warm air curing was performed. Compared with microwave curing, it took time for the temperature to rise sufficiently to the inside of the material, so the curing time after construction was longer than with microwave curing.

Claims (1)

In the casting construction method of the irregular refractory formed by kneading the raw material blend and water,
A pouring step of pouring an amorphous refractory to which a curing modifier is added so as to have a pot life of twice or more of the pouring construction time when the temperature of the irregular refractory after kneading is 35 ° C .;
A curing process for irradiating microwaves to the amorphous refractory poured by the casting process,
Casting method of irregular refractories including