DE2552823C2 - Process for the production of a metallurgically effective fluorspar-free slag - Google Patents

Description

containing substances. So was z. B. observed that when adding 400 kg of aluminum phosphate instead of 200 kg fluorspar after two minutes the same slag height as when the fluorspar was added.

An increased liquefying effect is therefore achieved if fluxes are used, which consist primarily of aluminum phosphates or substances containing aluminum phosphate, which are low Amounts of borate in a replacement ratio of 1: 2 (one part of boronite has the same effect as two parts of aluminum phosphate I will be admitted.

In this procedure, the initial phosphate content of the liquid iron used is used of approx. 0.2% P, as is customary for the blow steel process, a phosphorus content of the finished steel of achieved less than 0.02% P, as can be seen from the following examples.

There are z. B. in a 50-tonne converter 451 liquid iron with 0.17% P is used. Depending on the silicon content, those in the following Lime and flux quantities listed in the table are added. The table also shows that when using aluminum phosphate instead of fluorspar with practically the same amount of slag the P content of the steel is only increased to the extent permitted.

Pig iron % Si % P lime Flux kg slag % PA stole t 0.60 0.170 t Art 200 t 2.4 % p 45 0.60 0.171 3.3 Fluorspar 400 6.5 4.1 0.012 45 0.80 0.171 3.3 Al-phosphate *) 200 6.7 2.1 0.016 45 0.80 0.172 3.7 Fluorspar 500 7.3 4.1 0.011 45 3.7 Al-phosphate *) 7.6 0.016

*) P, O ₅ content in the aluminum phosphate approx. 30%.

Claims (5)

the exhaust gases are emitted and thus can exert a negative impact on the world. For this reason a number of attempts are made 1. Process for the production of a metallurgically carried out, which replaces the fluorspar effective flußspatfrera, essentially from 5 to keep other fluxes to the goal. So were Lime existing slag for basic steel z. B. aluminum, manganese, T.Unoxyd, iron oxide production process Tried with the use of liquids containing substances, Ilmenite sand and Ol.v.n (56 "« Iron with phosphorus contents of S 0.2% P and National Open Hearth and Basic Oxygen Steel Confe for the manufacture of steels with non-essentials 1973). Furthermore, substances containing borate were used lent phosphorus contents lower than 0.02% P, io used (Stahl und Eisen, 92, 1972, No. 4, p. 255- characterized in that as 259, and no. 6, pp. 260-262) Flux aluminum phosphate or aluminum- Only fluorspar- phosphate-containing substances are added. and borate-containing fluxes are preserved. All other 2. Process for producing a metallurgically failed because they either Effective fluorspar-free slag for basic 15 caused insufficient desulfurization Steelmaking processes formed when using liquid or too viscous slag, so that the Iron with phosphorus contents were slowed down by significantly more metallurgical reactions. than 0.2% P and / or for the production of In addition, it turned out that the liquefaction Steels with much less phosphorus - the lime ran too slowly, so that these substances held as 0.02% P, characterized, could only be used when fluoride or that fluxes are used, which were also added before borates. predominantly made of aluminum phosphates or alumi- Another disadvantage of using There are substances containing phosphate, which borates are based on the fact that, depending on the melt flow small amounts of borates in a replacement ratio of 1: 2, boron can be absorbed into the steel, (One part of borate has the same effect as two parts of AIu- 25 In addition, the use of minium phosphate) can be added. Fluorides and borates reduce the effectiveness of the 3. The method according to claim 1 or 2, characterized by slag produced fertilizer significantly because characterized in that the aluminum phosphate or part of the fertilizing effectiveness is based on the phosphorus Aluminum phosphate-containing substances in the bulk content of the slag is based. So z. B. the addition able earth-moist or dry state 3 ° of fluorspar or other fluorides to form be admitted. of fluorapatite, which only dissolves in strong acids 4. Flußspat-free slag-forming agent can be essentially and thus also from extremely finely thickened slag consisting of lime for basic steel-milled slag is practically not released into the soil-generating process when using liquid. The addition of boron-containing substances iron with phosphorus contents of ^ 0.2% P and 35 leads to a release of borates into the soil, for the production of steels with not significantly lower phosphorus contents than 0.02%, which does not affect the phosphorus release. However, the growth of plants is characterized by the fact that, as a flux, B ₂ O ₃ uptake is impaired. Containing substances are included as a limit for aluminum phosphate or aluminum _{phosphate - the permissible B 2} O _{3 levels in fertilizers.} 40 to consider a few hundredths of a percent. Should the 5. Use of the slag according to claim 1 or 2 as fertilizer, slag obtained for the production of phosphate, the process must not be operated with fluorspar- nor with borate- and lime-containing fertilizers with phosphate-containing substances in such amounts 3% P ₂ O ₅ . as they are in themselves for metallurgical effectiveness 45 would be required. The object of the invention is to provide a method for To create a slag for basic steelmaking processes that is both metallurgically effective and suitable for fertilization purposes.
50 To solve this problem, according to the invention The invention relates to a method for producing a method for producing a metallurgically a metallurgically effective fluorspar-free, in the effective fluorspar essentials that can be used for fertilizers slag consisting of lime, which is suggested for free slag, the one for basic steel-basic Steel production process when using production processes of the above-mentioned type liquid Iron is turned with phosphorus content of 0.2% P 55 g, characterized in that instead and for the production of steels with a minor amount of fluorspar or borates as a flux of aluminum Phosphorus contents lower than 0.02% P anphosphate or substances containing aluminum phosphate are used and also for the production of fertilizer. The addition of the aluminum phosphate can be used, as well as a slag former phats or the aluminum phosphate-containing substances for this purpose. 60 takes place in a pourable earth-moist or To achieve a metallurgically effective slag dry state. it is customary to add fluorspar as a flux. It is also the use of the slag obtained (DT-OS 19 16 419 and DT-AS 19 55 869). With this addition to the production of phosphate and lime-containing additions, the rate of dissolution of the lime fertilizers with phosphate contents is to be increased by more than (Ironmaking and Steelmaking, 1975, 65 3% P ₂ O ₅ claimed. Volume 1, No. 2, p. 115). The addition of fluorspar It has surprisingly been found that however, it has the disadvantage that aluminum phosphate contains about the same liquefying fluoride in steel production Gases or dusts arise that have an effect on the slag such as fluorine or boron