CN1690012A

CN1690012A - Electric furnace bottom dry ramming mass and its making method

Info

Publication number: CN1690012A
Application number: CN 200410018075
Authority: CN
Inventors: 蓝振华
Original assignee: PENGPU SPECIAL REFRACTORY FACTORY SHANGHAI
Current assignee: Shanghai Pengpu Special Refractory Material Factory Co., Ltd.
Priority date: 2004-04-29
Filing date: 2004-04-29
Publication date: 2005-11-02
Anticipated expiration: 2024-04-29
Also published as: CN1300043C

Abstract

The present invention is dry refractory ramming material for bottom of electric furnace and its preparation process. The dry refractory ramming material consists of magnesia-calcium oxide- ferric oxide sand and high purity fused magnesia. The magnesia-calcium oxide- ferric oxide sand is prepared with the materials including MgO, CaO, Fe2O3, Al2O3, SiO2, burnt IL and other material in certain proportion and through sintering in rotary kiln at 1700-1750 deg.c, and has density not lower than 2.5 g/cu cm. The high purity fused magnesia has critical granularity of 10 mm and accounts for 0-75 wt%. The preparation process of the dry refractory ramming material includes preparation of magnesia-calcium oxide- ferric oxide sand and grading based on Andrassen formula. The dry refractory ramming material has no cracking and high corrosion resistance and can meet the requirement of use in steel making electric furnace.

Description

Electric furnace bottom dry rammingmaterial and preparation method thereof

Technical Field

The invention relates to the field of electric furnace steelmaking, in particular to an electric furnace bottom dry-type ramming mass (trade name: PN-novel electric furnace bottom dry-type ramming mass) and a preparation method thereof.

Background

The electric furnace steelmaking is a short-flow steelmaking mode which recycles scrap steel, is environment-friendly, energy-saving, rapid and efficient, and rapidly develops and drives MgO-CaO-Fe₂O₃Is a rapid research and development and comprehensive popularization of the ramming material at the bottom of the electric furnace. For example, Bao Steel 150 ton ultra high Power DC arc furnace is available from Clecim, FranceAnd introducing the steel, wherein the capacity is 190 tons, the steel is left for 40 tons of operation, the scrap steel is added with molten iron, a double-furnace-base alternative smelting mode is adopted, the tapping temperature is 1600-1650 ℃, and the average tapping time is 60 minutes. Because the smelting production adopts the technologies of composite blowing, oxygen lance fluxing, foam slag submerged arc and the like, the steelmaking process has ultrahigh power and fast rhythm operation, the overhaul times and the shutdown time of the furnace bottom are reduced as much as possible, thus the ramming material at the bottom of the electric furnace is required to be simple and convenient to construct, can be subjected to cold repair and hot repair, and can be immediately put into smelting after being repaired; the high-temperature resistant steel is quickly sintered into a compact and solid whole at medium temperature, does not have too much liquid phase at high temperature, has good high-temperature structural strength, resists the erosion of slag and the impact of scrap steel, can withstand intermittent operation of smelting, and has good rapid cooling and rapid heating resistance.

At present, the 2CaO and Fe are commonly used at home and abroad₂O₃Is magnesium and is rich in 3 CaO. Fe₂O₃A magnesium dolomite mixture; but the defects of cracking, turning and poor melting loss resistance caused by over-thick sintering layer generally exist.

Disclosure of Invention

The invention aims to solve the technical problem of providing an electric furnace bottom dry ramming material and a preparation method thereof, and aims to solve the defects.

In order to solve the technical problems, the invention is realized by the following technical scheme:

the electric furnace bottom dry-type ramming mass contains magnesium calcium iron sand and high-purity fused magnesia; wherein: the Mg-Ca-Fe sand contains MgO (30-83%), CaO (55-8.5%), and Fe₂O₃(1％-8％)，Al₂O₃(≤1.3％)，SiO₂Less than or equal to 1.5 percent, less than or equal to 1.0 percent of burning IL, less than or equal to 3.2 percent of other material property, more than or equal to 2.5g/cm³) (ii) a The critical granularity of the high-purity fused magnesia is 10mm, and the introduction amount of the particles is 0-75 percent;

the preparation method is realized by the following steps:

the preparation of the magnesia-calcium-iron sand comprises the following steps: selecting raw materials and re-burning in a rotary kiln; wherein, the raw material selection comprises MgO (30-83 percent) and CaO (55 percent)-2.5％)，Fe₂O₃(1％-8％)，Al₂O₃(≤1.3％)，SiO₂Less than or equal to 1.5 percent, less than or equal to 1.0 percent of burning IL, less than or equal to 3.2 percent of other material property, more than or equal to 2.5g/cm³) (ii) a The re-burning temperature of the rotary kiln is 1700-1750 ℃;

electric furnace bottom dry ramming mass utilizes Andreassen formula y as 100(D/D)^qCarrying out optimal particle size distribution, wherein the q value is generally 0.19-0.45;

compared with the prior art, the invention has the beneficial effects that: the method solves the fatal defects of cracking and poor corrosion resistance caused by over-thick sintering layer, fully meets the requirements of electric furnace steelmaking such as Bao steel 150-ton ultrahigh-power direct-current electric arc furnace and foreign steel mills, and creates good economic benefit and social benefit.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments below:

example 1

The electric furnace bottom dry-type ramming mass contains magnesium calcium iron sand and high-purity fused magnesia; wherein: the Mg-Ca-Fe sand contains MgO 30%, CaO 55% and Fe₂O₃8％，Al₂O₃1.3％，SiO₂1.5 percent of burning reduction IL1.0 percent, 3.2 percent of other material property, dense body (not less than 2.5 g/cm)³) (ii) a The critical granularity of the high-purity fused magnesia is 10mm, and the introduction amount of the particles is 0 percent;

the preparation method is realized by the following steps:

the preparation of the magnesia-calcium-iron sand comprises thefollowing steps: selecting raw materials and re-burning in a rotary kiln; wherein the raw material selection comprises MgO 30%, CaO 55%, Fe₂O₃8％，Al₂O₃1.3％，SiO₂1.5 percent of burning reduction IL1.0 percent, 3.2 percent of other material property, dense body (not less than 2.5 g/cm)³) (ii) a The re-burning temperature of the rotary kiln is 1700 ℃;

electric furnace bottom dry ramming mass utilizes Andreassen formula y as 100(D/D)^qCarrying out optimal particle size distribution, wherein the q value is 0.19;

example 2

The electric furnace bottom dry-type ramming mass contains magnesium calcium iron sand and high-purity fused magnesia; wherein: the Mg-Ca-Fe sand contains MgO 83%, CaO8.5% and Fe₂O₃4.1％，Al₂O₃0.45，SiO₂0.78, burning reduction IL0.11, other properties 3.06, dense (not less than 2.5 g/cm)³) (ii) a The critical granularity of the high-purity fused magnesia is 10mm, and the introduction amount of the particles is 75 percent;

the preparation method is realized by the following steps:

the preparation of the magnesia-calcium-iron sand comprises the following steps: selecting raw materials and re-burning in a rotary kiln; wherein the raw materials comprise MgO 83%, CaO8.5%, and Fe₂O₃4.1％，Al₂O₃0.45，SiO₂0.78, burning reduction IL0.11, other properties 3.06, dense (not less than 2.5 g/cm)³) (ii) a The re-burning temperature of the rotary kiln is 1750 ℃;

electric furnace bottom dry ramming mass utilizes Andreassen formula y as 100(D/D)^qCarrying out optimal particle size distribution, wherein the q value is 0.45;

example 3

The electric furnace bottom dry-type ramming mass contains magnesium calcium iron sand and high-purity fused magnesia; wherein: the Mg-Ca-Fe sand contains MgO 63%, CaO27.6%, and Fe₂O₃5％，Al₂O₃0.9％，SiO₂0.8 percent of burning reduction IL0.5 percent, 2.2 percent of other material property, dense body (not less than 2.5 g/cm)³) (ii) a The critical granularity of the high-purity fused magnesia is 10mm, and the introduction amount of the particles is 45 percent;

the preparation method is realized by the following steps:

the preparation of the magnesia-calcium-iron sand comprises the following steps: selecting raw materials and re-burning in a rotary kiln; wherein the raw materials comprise MgO 63%, CaO27.6%, and Fe₂O₃5％，Al₂O₃0.9％，SiO₂0.8 percent of burning reduction IL0.5 percent, 2.2 percent of other material property, dense body (not less than 2.5 g/cm)³) (ii) a The re-burning temperature of the rotary kiln is 1730 ℃;

bottom of electric furnaceFormula ramming mass using Andreassen formula y as 100(D/D)^qCarrying out optimal particle size distribution, wherein the q value is 0.30;

the raw material selection, the physical and chemical indexes of the raw material and the finished product, and Andreassen formula y as 100(D/D)^qThe relationship between the q value and the body density and the product example are described as follows:

1. selection of raw materials

From the analysis of domestic and foreign data, MgO-CaO-Fe₂O₃The ramming material for the bottom of the electric furnace generally takes fused magnesia and magnesia-calcium-iron sand as main raw materials and does not contain additives, so that the selection and control of the raw materials are particularly important, especiallyThe selection of the magnesium-calcium-iron sand and the matching of the addition amount of the magnesium sand. Guided by a phase diagram, from MgO-CaO-FeO_nIn a ternary phase diagram, MgO-CaO-FeO_nWhen the refractory is in equilibrium with Fe (i.e. under steelmaking conditions), as long as the composition point falls within the range of MgO-CaO-MgO/Fe₂O₃When the temperature is within the triangle of 2.33, a liquid phase does not appear under 1600 ℃, and the composition is MgO-solid solution or MgO-solid solution + CaO-solid solution, so that the durability is good.

(1) Control of Fe2O3 ① produces a liquid phase at moderate temperatures to form a dense sintered body, which reacts as follows, (C₂f, melting point 1449 ℃), (C₄AF, melting point 1415 ℃), and promotes rapid sintering of the ramming mass at the bottom of the furnace due to the generation of liquid phase.

② at high temperature, C₂F decomposition of Fe₂O₃Becomes FeO, MgO and FeO form an infinite solid solution at the temperature of about 1436 ℃ to form a magnesium-rich body, thereby achieving the compact high-temperature ceramic combination; from the phase diagram, the finished product Fe₂O₃The content of the magnesium, calcium and iron sand is controlled within 5 percent, and the content of the magnesium, calcium and iron sand is controlled to be about 7 percent;

(2) and (3) CaO control: due to FeO_nMuch less durable than MgO or CaO, so Al in the material₂O₃、Fe₂O₃、SiO₂The impurities should react withCaO sufficiently, and the climate of the air humidity in the Shanghai is consideredCharacterized by adopting MgO-CaO-Fe without fCaO type₂O₃Is a furnace bottom ramming material of an electric furnace. If CaO is too low, MgO-CaO-Fe cannot be added₂O₃The ramming material at the bottom of the electric furnace and impurities in molten steel completely react, and low-melting substances exist, so that the electric furnace is not durable; if CaO is too high, good sintering may not be formed due to lack of sufficient liquid phase at high temperature, resulting in deterioration of service properties. The MgO/CaO ratio is controlled to be more than 3 when the high-temperature operation is carried out; under the condition of ultrahigh temperature operation, the ratio of MgO/CaO is controlled to be about 9; the saturation degree of CaO is controlled to be 1.1Al₂O₃+0.7Fe₂O₃+2.8SiO₂A range;

(3)SiO₂the control of (2): from MgO-CaO-SiO₂In the ternary phase diagram, the temperature of the liquid phase is not low, but SiO₂React with CaO to generate 2CaO&SiO₂And 3 CaO. SiO₂2 CaO. Fe on the surface of periclase₂O₃The MgO-CaO refractory is extruded out, so that the MgO-CaO refractory lacks a sintering aid and is difficult to sinter. And 2CaO SiO₂Phase change occurs below 1200 deg.C: with about 10% to 20% volume expansion, causing the material to crumble; therefore, the content of silicon dioxide in the raw material of the magnesia-calcium sand is controlled to be SiO₂Not more than 1.5 percent, and SiO in the product is controlled₂≤1.5％；

(4)Al₂O₃The control of (2):

melting point 1415 ℃ C.) at C₄In the presence of AF, the lowest eutectic point of MgO-CaO is reduced from 2300 ℃ to 1320 ℃The temperature is higher than the melting point of the magnesium oxide, the magnesium oxide is stable in liquid phase, a solid solution cannot be formed, and the corrosion resistance of the material is greatly reduced, wherein the magnesium oxide is MgO-CaO-FeO_nControlling Al in the mixture₂O₃＜1.3％；

(5) Selection of preparation process of magnesium-calcium-iron sand

The preparation process of the magnesium-calcium-iron sand adopts a rotary kiln with the temperature of 1700-1750 ℃ for re-burning, the temperature of the rotary kiln is uniform, the material components and the burnt material are good, and the high-temperature burnt densification is good. The down-draft kiln has uneven temperature and difficult control of raw material components. The furnace age of the magnesia-calcia-iron sand furnace of Shandong inverted-flame kiln factory is 1450, the furnace age of the magnesia-calcia-iron sand furnace re-fired by a rotary kiln of Liaoning factory is more than 1650, and the furnace age is 1900 at most. Therefore, we use the magnesia-calcium-iron sand re-burned in the rotary kiln of Liaoning factory at a fixed point.

2. Physical and chemical indexes of raw materials and finished products

In summary, in combination with the specific circumstances of the use environment, we controlled the raw material and finished product indexes as the following table (%)

	MgO％	CaO％	Fe₂O₃％	Al₂O₃％	SiO₂％	IL％	Body density g/cm³	Other material property%
	MgO％	CaO％	Fe₂O₃％	Al₂O₃％	SiO₂％	IL％	Body density g/cm³	Other material property%	Magnesium calcium iron	30～83	2.5～55	1～8	≤1.3	≤1.5	≤1.0	≥2.50	0-1
Finished product	≥55	0～30	0～12.5	≤1.6	≤2.0	≤1.0	≥2.30	0-1	Magnesium calcium iron	30～83	2.5～55	1～8	≤1.3	≤1.5	≤1.0	≥2.50	0-1

Andreassen formula y as 100(D/D)^qRelation between medium q value and body density

The critical particle size is 10mm, and the relationship between the bulk density and the q value of the finished product is as follows:

q value	0.19	0.24	0.29	0.34	0.39	0.45
q value	0.19	0.24	0.29	0.34	0.39	0.45	The density of the finished product is g/cm³	2.43	2.50	2.61	2.57	2.45	2.37

4. Examples of products

The on-site use tracking finds that similar products at home and abroad crack in the using process, so that the defects of furnace bottom turnover and rapid erosion are caused. According to MgO-CaO-Fe₂O₃The characteristics of the ramming material for the bottom of the electric furnace and the use environment of the ramming material are proved by repeated experiments, high-purity fused magnesia is introduced, the critical granularity is increased to 10mm, and the aims of reducing cracking and improving durability are fulfilled. Then using Andreassen formula y as 100(D/D)^qAnd (3) carrying out optimal particle grading, wherein the q value is generally 0.19-0.45 according to specific conditions so as to achieve closest packing and improve the erosion resistance. According to different requirements, the common manufacturers design that magnesium calcium iron sand particles are added with fused magnesia fine powder, the introduction amount of the magnesia powder is 0-25 percent, and the method comprises the following steps ofThe sintering thickness is often too large, the temperature is rapidly reduced after tapping, the cooling shrinkage is large, the steel is cracked and infiltrated, furnace bottom material overturning is repeatedly caused to block a tapping hole, accidents such as high temperature of a furnace shell and a bottom electrode are caused, the magnesia-calcium-iron sand is extremely high, the transport and the storage are difficult due to extremely high hydration, the corrosion resistance is reduced after moisture absorption, moisture absorbed by the moisture is vaporized in the temperature rising process, volume expansion of 1244 times is generated, and the material is easy to bulge and crack. The introduction amount of the high-purity fused magnesia is 30-45%, and the high-purity fused magnesia is from particles to fine powder; the critical particles are designed into high-purity fused magnesite of 10mm, so that the addition amount of the magnesium-calcium-iron sand material is reduced, and the adverse effect caused by over-sintering or hydration is greatly reduced. The addition of the high-purity fused magnesia can also improve the erosion resistance of the material, and the increase of the critical granularity improves the thermal shock resistance of the material. This is our unique design. Specific products are given in the following table

Square block Table (A table)	MgO ％	CaO ％	Fe₂O₃ ％	Al₂O₃ ％	SiO₂ ％	IL ％	Others Material property ％	Body density g/cm	Magnesium alloy Sand	Magnesite clinker Granules ％	Normal temperature compressive strength (Mpa)
											Normal temperature compressive strength (Mpa)			1300℃ ^*3h	1500℃ ^*3h	1600℃ ^*3h
											①	93.63	0.34	1300℃ ^*3h	1500℃ ^*3h	1600℃ ^*3h	4.42	0.23	0.32	0.10	0.96	2.68	95	75	5.1	27.0	35.4
②	86.86	8.21	2.76	0.38	0.63	0.18	0.98	2.65	50	42	①	93.63	0.34	15.7	37.2	48.5	4.42	0.23	0.32	0.10	0.96	2.68	95	75	5.1	27.0	35.4
②	86.86	8.21	2.76	0.38	0.63	0.18	0.98	2.65	50	42	③	84.73	9.87	15.7	37.2	48.5	3.32	0.46	0.68	0.23	0.71	2.64	40	35	38.0	49.0	52.0
④	82.60	11.51	3.89	0.53	0.79	0.29	0.39	2.61	30	24	③	84.73	9.87	40.5	50.6	60.0	3.32	0.46	0.68	0.23	0.71	2.64	40	35	38.0	49.0	52.0
④	82.60	11.51	3.89	0.53	0.79	0.29	0.39	2.61	30	24	⑤	72.41	20.22	40.5	50.6	60.0	5.25	0.36	0.45	0.35	0.96	2.58	10	10	51.8	63.5	72.0

Claims

1. The utility model provides an electric stove bottom dry-type ramming mass which characterized in that: contains magnesium calcium iron sand and high-purity fused magnesia; wherein: the Mg-Ca-Fe sand contains MgO (30-83%), CaO (55-8.5%), and Fe₂O₃(1％-8％)，Al₂O₃(≤1.3％)，SiO₂Less than or equal to 1.5 percent, less than or equal to 1.0 percent of burning IL, less than or equal to 3.2 percent of other material property, more than or equal to 2.5g/cm³) (ii) a The critical granularity of the high-purity fused magnesia is 10mm, and the particle introduction amount is 0-75%.

2. The electric furnace bottom dry ramming mass according to claim 1, characterized in that: the Mg-Ca-Fe sand contains MgO 63%, CaO27.6%, and Fe₂O₃5％，Al₂O₃0.9％，SiO₂0.8 percent of burning reduction IL0.5 percent, 2.2 percent of other material property, dense body (not less than 2.5 g/cm)³) (ii) a The critical granularity of the high-purity fused magnesia is 10mm, and the particle introduction amount is 45 percent.

3.A method for preparing the compound of claim 1, comprising the steps of:

the preparation of the magnesia-calcium-iron sand comprises the following steps: selecting raw materials and re-burning in a rotary kiln; wherein, the raw material selection comprises MgO (30-83%), CaO (55-2.5%), Fe₂O₃(1％-8％)，Al₂O₃(≤1.3％)，SiO₂Less than or equal to 1.5 percent, less than or equal to 1.0 percent of burning IL, less than or equalto 3.2 percent of other material property, more than or equal to 2.5g/cm³) (ii) a The re-burning temperature of the rotary kiln is 1700-1750 ℃;

electric furnace bottom dry ramming mass utilizes Andreassen formula y as 100(D/D)^qThe optimal particle size distribution is carried out, and the q value is generally 0.19-0.45.

4. The production method according to claim 3: wherein the raw materials comprise MgO 63%, CaO27.6%, and Fe₂O₃5％，Al₂O₃0.9％，SiO₂0.8 percent of burning reduction IL0.5 percent, 2.2 percent of other material property, dense body (not less than 2.5 g/cm)³) (ii) a The re-burning temperature of the rotary kiln is 1730 ℃;

electric furnace bottom dry ramming mass utilizes Andreassen formula y as 100(D/D)^qThe optimum grain size distribution was carried out, and the q value was 0.30.