CN100493771C - Continuous casting protection slag - Google Patents
Continuous casting protection slag Download PDFInfo
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- CN100493771C CN100493771C CNB2006100282535A CN200610028253A CN100493771C CN 100493771 C CN100493771 C CN 100493771C CN B2006100282535 A CNB2006100282535 A CN B2006100282535A CN 200610028253 A CN200610028253 A CN 200610028253A CN 100493771 C CN100493771 C CN 100493771C
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- covering slag
- continuous casting
- cooling water
- cao
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Abstract
The invention relates to a continuous casting mould fluxes, especially a low-pollution continuous casting mould fluxes. The invention mainly solves technical problems that because fluoride ion increases continuous casting equipment is eroded, post-processing difficulty is increased and treatment cost is increased. The technical project in invention is that the low-pollution continuous casting mould fluxes comprises 28-35% by wt of CaO, 28-34% by wt of SiO2, 3-7% by wt of Al2O3, 8-13% by wt of Na2O, 3-5% by wt of F, 3-5% by wt of B2O3, 1-5% by wt of Li2O, 3-5% by wt of MnO and 4-8% by wt of MgO. The weight ratio of CaO and SiO2, CaO/SiO2, is controlled more than 1. Pollution component index, (8F%+ 1.2SiO2%+B2O3%+Al2O3%+MnO%)/(0.8CaO%+Na2O%+Li2O%+MgO%), is less than or equal to 2.4. Obtained protection fluxes in the invention can not only satisfy various performance indexes of protection fluxes but also control pollution degree of cooling water under two grades so as to satisfy discharging requirement of environmental protection.
Description
Technical field: the present invention relates to a kind of continuous casting covering slag.
Background technology:
Fluorine in the continuous casting covering slag is one of flux of the most normal use, and in the existing continuous casting covering slag, fluorine content is generally between 5～10%.With respect to other flux in the covering slag (soda ash, borax etc.), fluorine can more effectively be regulated viscosity coefficient of dross, and less to the fusion temperature influence of slag, thereby the serviceability of viscosity and melting temperature better performances ground and covering slag is complementary.In addition on the one hand, the heat transfer between the crystal property of covering slag and strand and the copper plate of crystallizer is closely related, and fluorine can significantly improve the crystallization temperature of covering slag, especially at the basicity (CaO/SiO of covering slag
2) surpass at 1.0 o'clock, more obvious to the raising of crystallization temperature, cuspidine (3CaO.2SiO in main and the high basicity covering slag
2.CaF
2) separate out relevantly, so fluorine can effectively improve the thermal resistance of covering slag slag film between crystallizer and strand, reduces the responsive steel grade cracking frequency of crackle.
Yet; molten mold flux at high temperature interacts with cooling water; make fluorinion concentration and acidity in the cooling water increase also constantly enrichment; the pH value of certain factory's continuous casting machine fan-shaped segment cooling water reaches 3.5; fluorinion concentration is up to more than the 200mg/L, causes the continuous casting installation for casting corrosion, has increased the difficulty of circulating water treatment; improve the cost of nertralizer, also strengthened the blowdown presssure of cooling water waste water.National Specification cooling-water drain standard, fluorinion concentration are not more than 10ppm (referring to GB3838-88).
Chinese patent 03117824.3 and United States Patent (USP) 6461402 all provide a kind of floride-free covering slag; the core of these two patents is substitutes of fluorine in the exploitation covering slag; use other flux such as Li2O, B2O3 to wait the fluorine that replaces in the covering slag, develop the floride-free covering slag that is applicable to specific steel grade serviceability.
Summary of the invention:
The purpose of this invention is to provide a kind of low-contamination type continuous casting protection slag, mainly solve because continuous casting installation for casting corrosion that the fluorine ion increase causes and the technical problem that post-processing difficulty increases and processing cost rises.
Technical thought of the present invention is: the fluorine in the molten mold flux to the pollution level of cooling water except outside the Pass the fluorine content with covering slag itself has; also relevant with other compositions of covering slag, that is to say the dissolving of fluorine in cooling water in other composition influence covering slags of covering slag.So the covering slag of identical fluorinated volume can differ greatly to the fluorinion concentration and the acidity influence of cooling water; the present invention has made full use of the important function of fluorine in covering slag; collocation by proper raw material; pollution level to cooling water is controlled at below the secondary, and a kind of low-contamination type covering slag is provided.
Technical scheme of the present invention is: a kind of continuous casting covering slag, the weight percent proportioning of its constituent is: CaO:28～35%, SiO
2: 28～34%, Al
2O
3: 3～7%, Na
2O:8～13%, F:3～5%, B
2O
3: 3～5%, Li
2O:1～5%, MnO:3～5%, MgO:4～8%.The weight ratio of control calcium oxide and silica is CaO/SiO
2Greater than 1,
Conventional covering slag compound method is adopted in the preparation of low-contamination type continuous casting protection slag.
The invention has the beneficial effects as follows: the present invention adopts thermal modeling test; studied the influence of the component in the molten mold flux to cooling water pH value and fluorinion concentration; test method: restrain the covering slag of de-carbon with 10 and put into 1350 ℃ of high temperature furnace graphite crucibles fusings after 8 minutes; take out and pour into fast in the stainless steel tank that holds the 200ml cooling water; even back to be cooled is removed residue and is got that water sample detects in the groove, the pH value of analysis water-like and fluorinion concentration.And the pollution level of cooling water is divided into four classes according to the pH value of cooling water and fluorinion concentration, see classification chart 1.National Specification (standard GB3838-88), cooling water fluorinion concentration are lower than 10mg/L and belong to first discharge standard; 10～20mg/L is a secondary standard, the low fluoride pollution type in the correspondence table.
Table 1: covering slag is to the cooling water pollution classification of type
| Classification | The covering slag classification | The pollutant component index | Influence to cooling water PH | To the influence of cooling water fluorinion concentration, mg/L |
| I | Pollution-free type | <1.5 | 9.0~8.0 | <5 |
| II | Low-contamination type | 1.5~2.4 | 9.0~8.0 | 5~20 |
| III | Middle contamination type | 2.4~2.6 | 8.0~6.5 | 20~35 |
| IV | The high pollution type | >2.6 | <6.5 | >35 |
The covering slag of reality and the ratio of cooling water during the ratio of covering slag and cooling water is produced far above continuous casting in the thermal modeling test; the former approximately is 25 times of the latter; that is to say if thermal modeling test draws this covering slag and belong to low fluoride pollution type; cooling water meets secondary discharge standard, when then using this covering slag in the actual production after the cooling water circulation 25 times discharging also belong to secondary discharge standard.
Test shows that pH value reduces (acidity increase) along with the fluorinion concentration in the increase cooling water of fluorine content increases, but when fluorine content greater than 5% the time, fluorinion concentration obviously rises in the cooling water, pH value obviously descends.Result of study has been found will reach the low-contamination type in showing no matter how other compositions of covering slag change, and fluorine element in the covering slag is necessary≤and 5%; Even also found the fluorine in the covering slag≤5% simultaneously; if there is not the reasonable combination of other compositions; also not necessarily become the low-contamination type covering slag; also may be middle contamination type or even high pollution type; this has illustrated the influence of also protected other components of slag of the dissolution of the fluorine element in the molten mold flux in water, so the low-contamination type covering slag is not only to fall the fluorine problem.
The reason that causes the pollution of cooling water be fluoride in the covering slag and cooling water reaction generate hydrofluoric acid water-soluble after, cause the acidity of cooling water and fluorinion concentration to rise.Covering slag mainly is to be undertaken by following reaction to the pollution of cooling water,
CaF
2+H
2O＝CaO+2HF
2CaF
2+SiO
2＝SiF
4+2CaO
SiF
4+2H
2O＝SiO
2+4HF
Different component has nothing in common with each other to the influence degree of above-mentioned reaction, and what have conditions each other.Basicity (the CaO/SiO of covering slag
2) be influential to the solubility behavior of fluorine in cooling water of covering slag.CaO and SiO
2Be the main component of covering slag, both sums are usually greater than 60% in covering slag, and test shows works as CaO/SiO
21 o'clock, the solubility of fluorine begins to reduce, and the influence of cooling water acidity is weakened.Illustrate that the increase of covering slag neutral and alkali oxide has suppressed the dissolving of fluorine, test shows along with Na
2O, Li
2The increase of O, MgO, these basic anhydride content of BaO, the solubility of fluorine begin to reduce, and cooling water acidity is influenced reduction approximately, CaO/SiO in this and the covering slag
2Increase similar rule is arranged.Test shows B
2O
3, Al
2O
3, these oxides of MnO and aforesaid oxide have opposite effect, i.e. B
2O
3, Al
2O
3, oxide such as MnO is acid in cooling water, these oxides help the dissolving of the F element in the covering slag.Above-mentioned oxide component is influenced in the molten mold flux F element dissolving situation in cooling water has carried out quantitative experimental study,, result of the test is carried out having obtained after mathematical regression is handled following relational expression also in conjunction with of the influence of fluorine content to the dissolving of F element:
Exponential quantity is big more, the then easy more dissolving of the F element in the covering slag, and having the greatest impact of F constituent content as can be seen from formula, coefficient reaches 8, however, because the absolute magnitude of the fluorine of allocating in the covering slag is limited, and CaO, SiO
2Higher etc. absolute magnitude, so CaO, SiO
2Influence also very big.Other composition is not all to allocate in the covering slag, and the amount of allocating into is limited, therefore a little less than the influence relatively to cooling water.Analog reslt shows that when " pollutant component index "≤2.4, the fluorinion concentration in the cooling water has reached secondary discharge standard, that is to say that this covering slag is the low-contamination type covering slag.The covering slag that the present invention obtains can satisfy every using property data of covering slag effectively, and the pollution level to cooling water is controlled at below the secondary simultaneously, has satisfied the requirement of environment protection emission.
The specific embodiment:
It in the table 2 correction data of two comparative examples of the present invention and 3 embodiment;
Comparative example 1 covering slag fluorine content is higher, reaches 6.91%, " pollutant component index " (8F%+1.2SiO
2%+B
2O
3%+Al
2O
3%+MnO%)/(0.8CaO%+Na
2O%+Li
2O%+MgO%) ratio is 2.61, exceeds 2.4, and this covering slag is very big to the influence of cooling water, and pH value is 4.8, and fluorinion concentration is 45.36mg/L, belongs to the high pollution type.Comparative example covering slag 2 fluorine content are 4.4%, and " pollutant component index " is 2.50, exceeds 2.4, and this covering slag is bigger to the influence of cooling water, and pH value is 6.9, and fluorinion concentration is 34.75mg/L, contamination type in the genus.
And be respectively 4.5%, 5.0% and 4.0% by covering slag embodiment 1, embodiment 2 and the embodiment 3 fluorine weight percentages of the present invention's preparation; " pollutant component index " is respectively 2.25,1.89 and 1.96; all be lower than 2.4; two covering slags are all less to the influence of cooling water, reach low contamination levels.As can be seen, although fluorine content is than comparative example 2 covering slag height in embodiment 1,2 covering slags, as long as rationally regulate the proportioning of " pollutant component index ", fluorine content is no more than 5% simultaneously, and covering slag can be controlled at low fluoride pollution level to the influence of cooling water.
Table 2 embodiments of the invention and original covering slag fluoride pollution type are relatively
Claims (1)
1, a kind of continuous casting covering slag, the weight percent proportioning of its constituent is: CaO:28～35%, SiO
2: 28～34%, Al
2O
3: 3～7%, Na
2O:8～13%, F:3～5%, B
2O
3: 3～5%, Li
2O:1～5%, MnO:3～5%, MgO:4～8%; And CaO/SiO
2Greater than 1; And control 8F%+1.2SiO
2%+B
2O
3%+Al
2O
3%+MnO%
8CaO％+Na
2O％+Li
2O％+MgO％
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|---|---|---|---|
| CNB2006100282535A CN100493771C (en) | 2006-06-28 | 2006-06-28 | Continuous casting protection slag |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100282535A CN100493771C (en) | 2006-06-28 | 2006-06-28 | Continuous casting protection slag |
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|---|---|
| CN101096049A CN101096049A (en) | 2008-01-02 |
| CN100493771C true CN100493771C (en) | 2009-06-03 |
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ID=39010250
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102712036A (en) * | 2010-01-21 | 2012-10-03 | 新日本制铁株式会社 | Mould powder for continuous casting of steel |
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|---|---|---|---|---|
| CN101530896B (en) * | 2008-03-14 | 2011-06-15 | 宝山钢铁股份有限公司 | High casting speed continuous casting covering slag used for ultra-low-carbon steel |
| CN101612652B (en) * | 2008-06-23 | 2011-06-15 | 宝山钢铁股份有限公司 | Mold powder for continuous casting of low nickel and high manganese stainless steel and preparation method thereof |
| CN101612653B (en) * | 2008-06-23 | 2011-04-13 | 宝山钢铁股份有限公司 | Mold powder for continuous casting of high aluminium-titanium-rare earth steel |
| CN102554161A (en) * | 2011-12-31 | 2012-07-11 | 西峡龙成冶金材料有限公司 | Covering slag of square billet continuous casting crystallizer and production method thereof |
| CN102825233B (en) * | 2012-07-31 | 2016-08-03 | 马鞍山科润冶金材料有限公司 | A kind of mould steel continuous crystallizer protecting slag and manufacture method thereof |
| CN102962420B (en) * | 2012-11-22 | 2014-12-17 | 河南省西保冶材集团有限公司 | Environmental-friendly low-carbon-steel fluorine-free casting powder for round billet |
| CN104107890B (en) * | 2013-04-19 | 2016-06-01 | 宝山钢铁股份有限公司 | A kind of cold rolled sheet steel continuous casting covering slag and manufacture method thereof |
| CN104607608B (en) * | 2015-01-29 | 2017-02-22 | 中南大学 | Medium manganese steel casting powder for automobile and application thereof |
| CN112247087A (en) * | 2019-07-22 | 2021-01-22 | 宝山钢铁股份有限公司 | Low-fluorine lithium-free covering slag for titanium-containing welding wire steel |
| CN112195304B (en) * | 2020-07-28 | 2022-02-18 | 龙南龙钇重稀土科技股份有限公司 | Core-spun yarn containing rare earth crystallizer pre-melted slag and application thereof |
| CN114210940B (en) * | 2021-12-24 | 2023-07-14 | 西峡龙成冶金材料有限公司 | Continuous casting crystallizer casting powder for YQ450NQR1 high-strength high-weather-resistance steel and application thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102712036A (en) * | 2010-01-21 | 2012-10-03 | 新日本制铁株式会社 | Mould powder for continuous casting of steel |
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