Design method for preparing electric furnace wall refractory material for rock wool from long-life hot molten slag, furnace wall and electric furnace

Abstract

The invention discloses a design method for preparing electric furnace wall refractory for rock wool from long-life hot molten slag, a furnace wall and an electric furnace, the method comprises the following steps: S1, selecting a silicon carbide castable or a chromium castable as the furnace wall refractory, arranging the furnace wall refractory on a furnace shell, and enabling the furnace wall refractory to be in direct contact with the furnace shell; and S2, in the production and operation process of the electric furnace, the amount of cooling water sprayed by the furnace wall in unit time is controlled to be 5-6 times of the weight of the rock wool melt, so that the rock wool melt forms a viscous slag adhering protection layer on the refractory material of the furnace wall. Effective cooling and thin furnace wall refractory materials are combined, furnace wall slag hanging is achieved through external cooling, a natural slag hanging protection layer is formed, the furnace wall refractory materials are prevented from being eroded, and it is ensured that the service life of the furnace wall refractory materials reaches one year or above.

Description

Technical Field

[0001] The invention relates to a rock wool preparation technology, and more specifically to a design method for an electric furnace wall refractory material for preparing rock wool from long-life hot molten slag, a furnace wall and an electric furnace. Background Art

[0002] Mineral (rock) wool is an inorganic fiber insulation material with the advantages of Class A non-combustibility, heat preservation, sound insulation, light weight, good durability, etc. It is widely used in building insulation and industrial insulation. The product is made of natural rocks or slag and other raw materials melted at high temperature, and formed by the combined action of centrifugal force and wind. Professionally, mineral wool and rock wool adopt the fiber acidity coefficient Mk=(W SiO2 +W Al2O3 ) / (W CaO +W MgO ), the acidity coefficient ≥1.6 is called rock wool, and the acidity coefficient <1.6 is called mineral wool.

[0003] At present, the manufacturing process of mineral (rock) wool has the following characteristics: cupola melting and electric melting furnace melting coexist, cold material production and hot slag raw material production coexist. Rock wool products are mainly made of cold material (basalt, dolomite, dry slag) as the main raw material, and adopt the manufacturing process of electric furnace or cupola melting; the products prepared by hot slag raw materials are all slag wool, single electric furnace melting process, adding a certain proportion of quenching and tempering materials, and the products are mainly granular wool and mineral wool board.

[0004] In the process of rock wool production, the equipment used to melt raw materials is mainly electric furnace, which uses graphite as electrode and uses the heat generated by electric current passing through the resistor to heat and melt the material. Under normal circumstances, the temperature of the melt in the furnace is controlled at about 1500℃; combined with Figure 1 As shown, the furnace body consists of three parts: a furnace cover 1, a furnace wall 2 and a furnace bottom 3; the furnace cover 1 is composed of several steel plates with water-cooling jackets, which are connected together at the furnace top and integrally cast by refractory castables. A graphite electrode 4 is installed on the furnace cover 1. The furnace wall 2 is generally an annular cylinder made of steel. The total height of the outer shell of the furnace wall 2 is about 3 to 3.5 meters. There is an open or closed cooling water system 7 outside the furnace wall 2. The furnace wall 2 is provided with a slag outlet 6. The furnace wall on the other side of the slag outlet is provided with an iron outlet 5. The furnace bottom 3 is supported by a steel structure and paved with refractory materials. In the entire production process, the service life of electric furnace refractory materials has become an important factor affecting the production line operation rate. Combined with Figure 2 As shown, the refractory materials for the furnace wall of general electric furnaces are often made of carbonaceous ramming materials (the layer that is in direct contact with the melt), thick-walled refractory materials with a thickness of 500 to 800 mm and a service life of about 4 to 8 months, and the refractory material life is short.

[0005] In recent years, in order to achieve the goal of energy conservation and carbon reduction in the rock wool industry, the raw materials used in the preparation of rock wool have been adjusted to reduce the use of natural mineral resources such as basalt and dolomite. The research on hot blast furnace slag cotton making has been devoted to the technical path of hot molten slag rock wool making. However, in the process of using hot blast furnace slag to make rock wool, it was found that the service life of the 600mm thick carbon refractory material of the furnace wall was very short, which could only last for 2 to 3 months. Each refractory maintenance required more than 20 days of shutdown and maintenance, which seriously reduced the operation rate of the production line. The working environment of the furnace wall refractory material is harsh, especially the slag line, which is subject to oxidation erosion, thermal shock erosion, scouring erosion, and chemical reduction erosion under the slag line. It can be seen that the hot blast furnace slag rock wool technology has very high requirements for the refractory material of the electric furnace wall. Summary of the invention

[0006] In view of the defects existing in the prior art, the purpose of the present invention is to provide a design method and furnace wall and electric furnace for long-life hot molten slag to prepare rock wool for electric furnace wall refractory, select silicon carbide castable or chromium castable as the electric furnace wall refractory, combine effective cooling with thinner furnace wall refractory, and realize the formation of a natural slag protective layer by external cooling to prevent the furnace wall refractory from being eroded, thereby ensuring that the service life of the furnace wall refractory reaches more than 1 year.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A first aspect of the present invention provides a method for designing a refractory material for an electric furnace wall for preparing rock wool using long-life hot molten slag, comprising the following steps:

[0009] S1, select silicon carbide castable or chromium castable as the furnace wall refractory material, cast the furnace wall refractory material on the inner side of the furnace shell, so that the furnace wall refractory material is in direct contact with the furnace shell;

[0010] S2. During the operation of the electric furnace, the amount of cooling water sprayed on the furnace wall per unit time is controlled to be 5 to 6 times the weight of the rock wool melt, so that the rock wool melt forms a viscous slag protective layer on the furnace wall refractory.

[0011] Preferably, in step S1, the thickness of the furnace wall refractory material is 150 to 200 mm.

[0012] Preferably, in step S2, the amount of cooling water sprayed on the furnace wall is 240-300m 3 / h.

[0013] Preferably, in step S2, during the production and operation of the electric furnace, the inlet temperature and outlet temperature of the furnace wall cooling water are monitored to ensure that the temperature difference between consecutive hours is not higher than 3°C, and at the same time, a thermal imager is used to detect the furnace wall of the electric furnace once every hour to ensure that the temperature change of the furnace wall of the electric furnace in a continuous period of time is ≤5°C.

[0014] Preferably, in step S2, the thickness of the slag protection layer formed on the furnace wall refractory is 1 to 20 mm.

[0015] Preferably, in step S2, the mass percentage composition of the rock wool melt is: SiO 2 40~45%,Al 2 O 3 12~15%, MgO 5~7%, CaO 26~30%, iron oxide 4~6%.

[0016] The second aspect of the present invention provides a long-life hot molten slag electric furnace wall for preparing rock wool, which is prepared according to the design method of the long-life hot molten slag electric furnace wall refractory for preparing rock wool according to the first aspect of the present invention, and is provided with a spray water system, which comprises a furnace shell and a furnace wall refractory provided on the furnace shell; the furnace wall refractory is selected from silicon carbide castable or chromium castable, and its thickness is 150-200mm;

[0017] The electric furnace wall also includes a cooling water sprayed during the production and operation of the electric furnace so that the rock wool melt forms a viscous slag protective layer on the furnace wall refractory material.

[0018] The third aspect of the present invention provides a long-life electric furnace for preparing rock wool with hot molten slag, comprising a furnace wall of the long-life electric furnace for preparing rock wool with hot molten slag as described in the second aspect of the present invention.

[0019] The effects of the present invention are as follows:

[0020] 1. The present invention can greatly increase the service life of the refractory materials of the electric furnace wall, reduce the downtime of the production line due to the maintenance of the electric furnace refractory materials, and thus improve the operation rate of the hot molten slag rock wool production line;

[0021] 2. The present invention selects silicon carbide castable or chromium castable as the furnace wall refractory material, so that it is in direct contact with the electric furnace shell, reduces the thickness of the furnace wall refractory material, and increases the amount of cooling water on the outside of the furnace wall; the present invention combines effective cooling with thinner furnace wall refractory material with good thermal efficiency and thermal conductivity, so that the temperature of the heating surface of the furnace wall refractory material decreases. Under thermal equilibrium, the rock wool melt becomes viscous on the heating surface of the refractory material as the temperature drops, and forms a natural slag protective layer to prevent the furnace wall refractory material from further erosion, thereby ensuring that the service life of the furnace wall refractory material is more than 1 year. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of an electric furnace for producing mineral wool using hot molten slag in the prior art;

[0023] Figure 2 It is a schematic diagram of the structure of the refractory material for the electric furnace wall used for making mineral wool from hot molten slag in the prior art;

[0024] Figure 3It is a schematic structural diagram of an electric furnace wall for preparing rock wool using long-life hot molten slag according to the present invention;

[0025] Figure 4 It is a schematic diagram of slag formation on the wall of an electric furnace for preparing rock wool with long-life hot molten slag according to the present invention;

[0026] In the figure, 1. furnace cover; 2. furnace wall; 3. furnace bottom; 4. graphite electrode; 5. iron outlet; 6. slag outlet; 7. cooling water system; 10. furnace wall refractory; 11. furnace bottom; 12. slag outlet; 13. cooling water system; 14. iron outlet; 15. slag protective layer. DETAILED DESCRIPTION

[0027] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0028] In order to solve the problem of short life of furnace wall refractory materials, silicon carbide castables, carbon ramming materials, chrome bricks and other refractory materials have been tried, but no improvement has been achieved. Through multiple experiments, the present invention found that the type of refractory material is not the most critical factor in achieving the long life of furnace wall refractory materials. The key to solving the problem is to select thin-walled refractory materials and realize self-protection of furnace wall slag hanging by external cooling.

[0029] Combination Figure 3 As shown, the present invention provides a design method for an electric furnace wall refractory material for preparing rock wool using long-life hot molten slag, comprising the following steps:

[0030] S1, select silicon carbide castable or chromium castable as the furnace wall refractory 10, and cast the furnace wall refractory 10 on the inner side of the furnace shell so that the furnace wall refractory 10 is in direct contact with the furnace shell;

[0031] This step is mainly aimed at the structure of the furnace wall refractory material 10. Silicon carbide castables or chromium castables are selected as the furnace wall refractory material 10. Silicon carbide castables and chromium castables have oxidation resistance and certain thermal conductivity. Figure 3 As shown, the furnace wall refractory material 10 is poured inside the furnace shell of the electric furnace, so that the furnace wall refractory material is in direct contact with the furnace shell without an intermediate filling layer, and the thickness is thin and the thermal resistance is small. The specific thickness can be controlled within 150-200 mm. In addition, the furnace wall refractory material used must meet the following properties: (1) The performance maintained at 110°C for 24 hours is as follows: Volume density ≥ 2.45 g / cm 3 , compressive strength ≥5MPa, flexural strength ≥60MPa; (2) the properties after calcination at 1450℃ for 3h are as follows: compressive strength ≥7MPa, flexural strength ≥80MPa, and the linear change rate after sintering is in the range of -0.4% to +0.4%.

[0032] S2, during the operation of the electric furnace, the amount of cooling water sprayed on the furnace wall per unit time is controlled to be 5 to 6 times the weight of the rock wool melt, so that the rock wool melt forms a viscous slag protective layer 15 on the furnace wall refractory material 10.

[0033] In this step, the main purpose is to form a slag protective layer 15 on the furnace wall refractory 10. A cooling water system 13 is provided on the outside of the furnace wall of the electric furnace, so when preparing rock wool, it can be achieved by controlling the amount of cooling water; since the thickness of the furnace wall is reduced in step S1, the amount of cooling water on the outside of the furnace wall needs to be increased in this step, so that the cooling effect is better; in addition, combined with the high-temperature viscosity curve of the rock wool melt, when the rock wool melt drops, the viscosity of the rock wool melt increases significantly, and the fluidity becomes worse, which effectively protects the furnace wall refractory. In this way, effective cooling is combined with thinner furnace wall refractory with good thermal efficiency and thermal conductivity, so that the temperature of the heating surface of the furnace wall refractory decreases. Under thermal equilibrium, the rock wool melt becomes viscous on the heating surface of the furnace wall refractory as the temperature drops, forming a natural slag protective layer 15 to prevent the furnace wall refractory from being further eroded.

[0034] During the preparation of rock wool melt, the amount of cooling water sprayed on the furnace wall per unit time is controlled to be 5 to 6 times the weight of the rock wool melt. The specific amount of cooling water sprayed on the furnace wall can be 240 to 300 m 3 / h. In addition, during the preparation of rock wool melt, the inlet and outlet temperatures of the furnace wall cooling water are monitored to ensure that the temperature difference between consecutive hours is no more than 3°C. At the same time, a thermal imager is used to detect the furnace wall once an hour to ensure that the temperature change of the furnace wall within a continuous period of time is ≤5°C. Finally, the thickness of the slag protection layer 15 formed by the rock wool melt on the furnace wall refractory 10 is ensured to be 1 to 20 mm.

[0035] The mass percentage composition of the rock wool melt prepared by the above method is: SiO 2 40~45%,Al 2 O 3 12~15%, MgO 5~7%, CaO 26~30%, iron oxide 4~6%.

[0036] The long-life hot molten slag electric furnace wall for preparing rock wool prepared by the design method of the long-life hot molten slag electric furnace wall is provided with a spray water system, and the electric furnace wall includes a furnace shell and a furnace wall refractory 10 arranged on the furnace shell; the furnace wall refractory 10 is made of silicon carbide castable or chromium castable, and its thickness is 150-200mm. The electric furnace wall also includes spraying cooling water during the production and operation of the electric furnace to form a viscous slag protective layer 15 on the furnace wall refractory 10 by the rock wool melt.

[0037] The present invention also provides an electric furnace for preparing rock wool with long-life hot molten slag, comprising the above-mentioned electric furnace wall for preparing rock wool with long-life hot molten slag.

[0038] Example

[0039] refer to Figure 3 As shown, the design method of a long-life hot molten slag for preparing rock wool in an electric furnace wall refractory is as follows:

[0040] (1) Electric furnace equipment and its parameters;

[0041] Specifications of the long-life hot molten slag electric furnace for preparing rock wool: outer diameter 4700mm, height 3295mm, electrode circle diameter 1386mm, graphite electrode diameter 300mm;

[0042] The furnace wall of the electric furnace for preparing rock wool with long-life hot molten slag is provided with a slag outlet 12, an iron outlet 14 and a cooling water system 13. The furnace wall of the electric furnace includes a furnace shell and a furnace wall refractory material 10 arranged on the furnace shell; the furnace wall refractory material 10 is made of silicon carbide castable material with a thickness of 150 to 200 mm. The physical and chemical indicators of the silicon carbide castable material are shown in Table 1;

[0043] Table 1 Physical and chemical indicators of electric furnace wall refractory 10

[0044]

[0045] (2) Formation of slag protection layer 15 and preparation of rock wool

[0046] During the operation of the electric furnace, the amount of cooling water sprayed on the furnace wall per unit time is controlled to be 240-300m 3 / h (i.e. the amount of cooling water is 5 times the weight of the rock wool melt), and at the same time, the inlet temperature and outlet temperature of the furnace wall cooling water are regularly monitored to ensure that the temperature difference between consecutive hours is not higher than 3°C; the electric furnace wall is inspected once an hour using a thermal imager, the temperature of each position of the electric furnace wall is recorded, and whether there are abnormally high temperature points is checked to ensure that the temperature change of the electric furnace wall in a continuous period of time does not exceed 5°C. Through the above operations, the rock wool melt forms a slag protective layer 15 with a thickness of 1 to 20 mm on the furnace wall refractory material 10.

[0047] The above method is used to obtain a rock wool melt with an acidity coefficient ≥ 1.6, and its composition is shown in Table 2; then it enters the subsequent rock wool preparation process.

[0048] Table 2 Composition of rock wool melt

[0049] chemical composition <![CDATA[SiO 2 ]]> <![CDATA[AL 2 THE 3 ]]> MgO CaO <![CDATA[Fe 2 EITHER 3 +FeO]]> scope% 40～45 12～15 5～7 26～30 4～6

[0050] In the above process, silicon carbide castables or chromium castables are selected as the refractory materials for the electric furnace wall. They have a certain thermal conductivity. The refractory materials are in direct contact with the electric furnace shell without an intermediate filling layer. They are thin and have low thermal resistance. The key is to increase the amount of cooling water on the outside of the furnace wall to enhance the cooling effect of the furnace wall, so that the rock wool melt forms a viscous slag protective layer on the heated surface of the furnace wall refractory materials. This can prevent the furnace wall refractory materials from further erosion, and the service life of the furnace wall refractory materials can reach more than 1 year.

[0051] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A design method for electric furnace wall refractory material for preparing rock wool with long-life hot molten slag, characterized in that: The following steps are involved: S1, select silicon carbide castable or chromium castable as the furnace wall refractory material, and cast the furnace wall refractory material on the inner side of the furnace shell so that the furnace wall refractory material is in direct contact with the furnace shell; S2. During the operation of the electric furnace, the amount of cooling water sprayed on the furnace wall per unit time is controlled to be 5 to 6 times the weight of the rock wool melt, so that the rock wool melt forms a viscous slag protective layer on the furnace wall refractory.

2. The design method of electric furnace wall refractory for preparing rock wool with long-life hot molten slag according to claim 1 is characterized by: In the step S1, the thickness of the furnace wall refractory material is 150 to 200 mm.

3. The design method of electric furnace wall refractory for preparing rock wool with long-life hot molten slag according to claim 1 is characterized by: In step S2, the amount of cooling water sprayed on the furnace wall is 240-300m 3 / h.

4. The design method of electric furnace wall refractory for preparing rock wool with long-life hot molten slag according to claim 1 is characterized by: In step S2, during the production and operation of the electric furnace, the inlet temperature and outlet temperature of the furnace wall cooling water are monitored to ensure that the temperature difference between consecutive hours is not higher than 3°C. At the same time, a thermal imager is used to detect the furnace wall of the electric furnace once every hour to ensure that the temperature change of the furnace wall of the electric furnace in a continuous period of time is ≤5°C.

5. The design method of electric furnace wall refractory for preparing rock wool with long-life hot molten slag according to claim 1 is characterized by: In the step S2, the thickness of the slag protection layer formed on the furnace wall refractory is 1 to 20 mm.

6. The design method of electric furnace wall refractory for preparing rock wool with long-life hot molten slag according to claim 1, characterized in that: In step S2, the mass percentage components of the rock wool melt are: SiO2 40-45%, Al2O3 12-15%, MgO 5-7%, CaO 26-30%, and iron oxide 4-6%.

7. A long-life hot molten slag electric furnace wall for preparing rock wool prepared by the design method of the long-life hot molten slag electric furnace wall refractory for preparing rock wool according to any one of claims 1 to 6, which is provided with a spray water system, characterized in that: It comprises a furnace shell and a furnace wall refractory material arranged on the furnace shell; The furnace wall refractory material is made of silicon carbide castable or chromium castable, and its thickness is 150-200mm; The electric furnace wall also includes a viscous slag protective layer formed on the furnace wall refractory material by spraying cooling water during the production and operation of the electric furnace.

8. A long-life electric furnace for preparing rock wool using hot molten slag, characterized in that: It comprises the furnace wall of an electric furnace for preparing rock wool with the long-life hot molten slag as described in claim 7.

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