SU954456A1 - Composition for treating hearth of heating furnaces - Google Patents

Description

The invention can be used by ferrous metallurgy enterprises, mainly in the process of removing liquid slag from heating furnaces and wells of rolling mills.

A known method for charging the bottom of the heating furnaces for removing slag from them in liquid form, comprising, by weight,% 3 blast-furnace granulated slag 50-65, coking 30-38, quartz sand - the rest ID.

Refueling material is relatively high as a result of the presence in its composition of a significant amount of expensive coke and less expensive but widely used for other purposes granulated blast furnace slag and quartz sand. In addition, the coking gas entering the kiln quickly burns out, which reduces the effectiveness of the filling material, and in the kilns there will be growths of unremoved slag.

The closest to the proposed is a known composition for filling the bottom of the heating furnaces, including, wt.%: Dolomite 65-85, coking - the rest 21.

A disadvantage of the known composition is its relatively high

streams, as it contains expensive combustible material - toxic. and dolomite. The coking at the heating temperatures of the metal in the furnaces quickly burns out, as a result of which the iron oxide () contained in the slag does not have time to completely recover to ferrous oxide (FeO) and the ability of the composition to liquefaction decreases.

10 slag.

This composition contains almost no active slag-forming silicon oxide (SiO, j), which is necessary to convert the refractory oxides FeO, MpO, ..., contained in the furnace slag, into fusible eutectic compounds with a melting point of 1150-1280 ° C. The composition also contains no oxides of alkali metals (, K, 0) and calcium fluoride (CaFii), which have a strong incinerating ability for furnace slag. The specified composition of the filling material does not allow

25 to transfer the entire volume of furnace slag to low-melting eutectic compounds, as a result, refractory slag build-ups will be formed in the furnaces, the removal of which will require

30 significant costs. . The purpose of the invention is to reduce the cost of removing the spike from the heating furnaces in the liquid state. The goal is achieved by the fact that the composition of the filler refills on the heating furnaces when the slag is removed in the liquid form, includes working molding earth, melted welding flux and dolomite. wt.%: Spent molding. earth 50-60 Spent welding flux 25-40 Dolomite,, 10-25 At the same time, the worked form on the earth contains, wt.%: Silicon oxide Alkaline earth metal oxides Alkali metal oxides per, aluminum and manganese marOstal exhaust welding flux keeps wt.% of silicon oxide, alkaline earth metal oxides calcium fluoride oxides of iron, aluminum and manganese marOstal The welding, the flux may contain alkali metal oxides impurities up to 0.6 wt.%. The composition includes waste molding ground, which is obtained by using for various types of casting liquid glass molding mixtures (quick-drying liquid glass mixtures, self-hardening mixtures), which are prepared on the basis of quartz sand with the addition of liquid glass and other components. The liquid glass molding mixture of steel casting is prepared in the following ratio of components (volume,%) t quartz sand 90, liquid glass fiber 9.5, fuel oil 0.5. Fractional particle size of the found molding sand is 0-25 mm. Spent welding flux is a waste of welding production, which is formed during the welding of metal structures under a layer of various types of fluxes having the initial composition of elements close to the composition of the spent flux. Dolomite is applied calcined, with a fraction of 0-25 mm, SiO - 1-3, CaO + + MgO - 88-98. To provide a wide temperature range for the liquid-mobile state of slag and more fully transfer it into low-melting eutectic compounds. The intervals of the content of elements in the materials of the composition are given in the table.

2-4

88-95

The components of the proposed composition, spent molding soil, spent welding flux and dolomite, are thinners of furnace slag.

Spent molding earth is a heat-treated material, which speeds up and facilitates its interaction with furnace slag. It contains active oxides - SiOtj, KACO, KiO, CaO, MgO, necessary for

1.5-3.0

Rest

conversion of refractory slag into low-melting compounds: 2FeSiO i, 3MnO-2SiOi, 2 (CaO, MgO). 4510 -Alj2 02, ZFeOtoO2SiOj. with melting points of 1150-1280 ° C and especially low-melting compounds (,) - FeO SiO-i with melting point 660750 ° C.

The spent welding flux is also a heat-treated material, which facilitates its interaction with the killer donkey; its composition contains active thinning oxides — SiOrj, CaO, MgO, and CaF. Oxides SiO / 2, CaO and MgO allow the slag composition to be converted into low-melting compounds with a melting point of 11501280 ° C, while calcium fluoride, CaF, is one of the main fluxes, reduces the viscosity of the slag, and activates oxidative processes in it. Calcined dolomite is also a heat-treated material, which basically contains the active oxides CaO, MgO, necessary to lower the melting point of the slag. Thus, the proposed stock for filling the hearth of the heating furnaces is not expensive, as it contains mainly production waste — spent molding soil and spent welding flux. Pre-treated materials containing active liquefying oxides SiOij, CaO, MgO, , CaF, which endows its interaction with furnace slag, allows the refractory slag to be converted into low-melting compounds and reduce the cost of its removal from the furnaces. To determine the ratio of components in this composition, tests were carried out on the furnaces of the sheet-rolling shop. The main results are given below. Experience 1. Composition, including, wt.%: Spent molding earth, 50% each, fraction 25 mm, spent welding flux 25%, fraction .25 mm and calcined dolomite with 25% fraction - 25 mm are mixed before use. The composition, at the rate of 70 kg per ton of slag formed, in portions of 10 kg is thrown onto the slag surface on the slag surface. Temperature is maintained in the slag. During the operation of the furnace, the liquid slag is removed by gravity from the slag through the tap holes. After conducting the experiment and stopping the furnace, no accretions of slag were found in the slags. Experiment 2. A composition is prepared that includes, in wt.% 5, spent molding soil with a 50% fraction - 2 mm, spent welding flux with a 40% fraction - 5 mm and dolomite with a 10% fraction - 5 mm. The composition is mixed before use and fed to slag in portions of 10 kg, at the rate of 50 kg per ton of slag. The temperature in the slag is 1320 ° C. During the operation of the furnace, the slag flows out of the slag through the summer, after stopping the furnace, no slag build-up was found in the slags, Experience 3. A composition is prepared that includes, in wt.%: Spent molding soil 50% in 15 mm fraction, spent welding flux 30% .Faction - 15 mm, dolomite 15% fraction - 155 mm. The composition is fed in portions of 10 kg at a rate of 60 kg per ton. The temperature in the slag 13. 1330 C. In the process of operating the furnace, the slag flows out of the slag-stone through the tap holes, after stopping the furnace, no slag build-up in the slag was detected. The composition is prepared from the following materials. 1.Well-up molding ground, obtained as a result of the use in foundry purposes of liquid-molding sand mixture of the following composition (volume,%) quartz sand 90, liquid glass 9.5, masto, 5. Spent molding earth contains, wt% SiO. 92, 2.1, CaO - "- MgO 2.3 and is taken with a fraction of 15 mm. 2. The waste welding flux formed during the welding of structures under a layer of flux AHB, containing, wt.%: SiO 45, CaO + MgO 8, 7. Fraction of flux particles 15 mm. 3. Annealed dolomite, containing, wt.%: CaO + MgO 97, fraction 15 mm. Before use, the composition is mixed and fed to the furnace on the surface of the slag formed periodically, in portions of 10 kg at the rate of 60 kg per ton of slag. The temperature in the furnace at the slag surface is maintained at 1330 ° C. Thus, the proposed composition contains pre-heat-treated materials that are non-deficient industrial waste, and as a result of the presence in it of a whole range of active thinning oxides: CaOj MgO,, KrjO, CaF-i allows the slag composition to be converted into low-melting compounds and removed in liquid form from furnaces. The use of the proposed composition makes it possible to eliminate the formation of slag buildup and reduce the cost of its removal. The economic effect will be obtained by reducing the repair of furnaces for slag removal; increasing the productivity of the hot rolling mill as a result of reducing furnace repairs, saving coke-blast furnace gas consumed to heat slag in slags, reducing the cost of composition, saving refractories consumed during repairs of furnaces. On the basis of the pilot industrial test of the proposed composition, the economic effect is due to a reduction of 2.5 tons of heat, an increase in the productivity of the rolling mill by 1.1 times, the economy of coke-house gas by 5%, saving of refractories and cheaper composition of more than 150 thousand. year. The proposed composition can be used iroko on heating

furnaces and wells 5lumingov, as it contains n-expensive materials available in metallurgical plants.

Claims (3)

1. The composition for refueling the furnace of the foaming furnaces when slag is removed in bulk form, which also, in order to reduce the costs of slag removal, it contains spent molding earth, spent welding flux and dolomite in the following ratio of components, weight.% Spent molding soil 50-60 Spent welding flux 25-4-0 Dolomi t10-25. 2. Composition POP.1, distinguished with, the fact that the waste molding sand contains, Bec.%: I: Alkaline-earth metal oxides2-4 Alkali metal oxides 1.5-3 Silicon oxide 88-95 Iron, aluminum and manganese oxides Rest 3. Composition POP.1, distinguished by the fact that the spent welding flux contains, wt%: . Silica 30-48 Alkaline-earth metal oxides 5-15 Calcium fluoride 5-9 Iron, aluminum and manganese oxides Rest Sources of information taken into account in the examination 1. USSR author's certificate No. 403777, cl. C 21 D 9/70, 1971. 2. USSR author's certificate No. 253852, cl. C 21 D 9/70, 1968.