JPS58153717A - Flux for refining and its using method - Google Patents

Abstract

PURPOSE:To economically profitably carry out the dephosphorization and desulfurization of hot metal, by a method wherein flux obtained at a low cost is used by feeding the flux having burnt trona ash as main component into hot metal at a certain rate and by mixing them. CONSTITUTION:The dephosphorization and desulfurization is carried out by feeding the flux having the trona ash burnt at a low temperature as main component of 10-20kg per 1ton of hot metal into hot metal and by mixing them. For the method of feeding this flux, the abovementioned flux is injected into the hot metal in a mixer car or an iron ladle together with inert gas such as N2, Ar, etc., or is fed during stirring hot metal with an impeller. Thereby, hot metal is caused to react with the flux, and the reactions of desulfurization and dephosphorization of hot metal are made to proceed at the same time. This method has plenty of economical merit because of using cheaper trona ash as raw materials by comparing the beforehand known refining method using extremely highly refined soda ash. That is, the decrease of cost may be obtained, for example, by not less than 30%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refining solvent used in the dephosphorization/desulfurization process of hot metal and a method for using the same.

Phosphorus and sulfur contained in the hot metal tapped from the blast furnace need to be removed because they cause deterioration of the quality of steel. It is being done.

In recent years, it has become possible to dephosphorize and desulfurize hot metal using a solvent whose main component is alkali metal charcoal, for example, soda ash mixed with an oxidizing agent such as fluorite, cholestonite, or iron oxide. It has been tried, and its effects have been found to be significant. According to this method, the usability of the dephosphorization/desulfurization agent is less than that of other conventional dephosphorization/desulfurization methods; for example, 10 to 20 kg of soda ash is required per unit of hot metal. In particular, since the dephosphorization process progresses efficiently and slag with good fluidity is obtained, the granular iron content in the slag is
It has the great advantage that there are very few
Furthermore, since the amount of slag generated is small, the slag can be easily disposed of.

As described above, the dephosphorization/desulfurization method mentioned above is a refining method that is attracting attention, but the major obstacle here is that the main ingredient, soda ash, is expensive. Traditionally, soda ash has been mostly consumed in the glass industry, ceramic industry, and chemical industry, so it has a high purity and is expensive as a refining industrial chemical. For example, as shown in the analysis below, this soda ash has a purity higher than that required by the steel industry.

Na2CO:s98, 5-99,
O%NaC,G O,5% S04 0.1% FeOO, 006% NaOHO, 2% NaHCO30.2% The purpose of the present invention is to avoid using chemicals similar to these high-purity first-class chemicals in the hot metal refining process. The object of the present invention is to provide a refining solvent that can be obtained at a low price, paying attention to the fact that it is not necessary to use it. Another object of the present invention is to provide a method for using a refining solvent that effectively uses the solvent described in 1-1.

1--To achieve the above-mentioned object The gist of the invention is a refining solvent characterized in that the main component is calcined trona ash.

Moreover, the gist of the present invention related to the above-mentioned invention is that in hot metal,
10 to 20 kg of a 17M solvent containing low-temperature fired trona ash as a component is added per ton of hot metal, and stirred with W.
This is a method of using a refining solvent, which is characterized by dephosphorizing and desulfurizing hot metal.

Here, trona ash is a naturally occurring rust substance, and its composition varies depending on the place of production, and some typical examples are as follows.

Example l NaHCO3.2H2050,7% Na HCO344,4% NaCl1l t, o%NaF
l , 28%CaCO30,25% 5i02 2.01% Example 2 NaHCO3,,,e2H2066,7%,1 NaHCO329,0% NaCN O,9% NaF 1.19%CaCO30,
21% 5i07 1.70%Example 3 Na2 co3 45.2% NaHCO, 35.7% NaFO, 9% Na2S0. 0.1% Water of crystallization 15.3% When these trona ash are calcined at a low temperature of 120 to 130°C, for example, Na2CO397,4 to 98.2% NaCρ 1.63 to 0.32% NaF 0.22- Approximately 0.30% becomes nails, and the other ingredients are Na HCOA.

Na2, S04, etc. are about 1% or less.

This calcination evaporates the adhering water and crystallized water in the trona ash, and also eliminates the moisture in NaHCO3, converting Na2 co
, it can be changed to . It is preferable that the firing humidity is relatively low as described in 1-1, but there is no problem in firing at a higher humidity for industrial production at other humidity, for example, Oosaka.

By blowing the solvent obtained by firing this I-ronaji into the 11N pig iron market or into the hot metal in a hot metal pot together with inert residues such as nitrogen and argon, or by adding the hot metal while stirring it with an impeller. When the hot metal and the solvent are reacted, the dephosphorization and desulfurization reactions of the hot metal proceed simultaneously.

For example, the dephosphorization reaction.

(415) [P co + Na2COA−(N a2o
)+ (215)(P2o, , )+C is represented by the reaction mechanism.

In addition, the solvent produced in this way contains Na2
It also contains halogen compounds such as SO2, NaF, and NaCρ, and these compounds bring about favorable results such as lowering the solidification temperature of the slag. In particular, soda ash does not contain NaF, and at present, fluorite, which is made of NaF, is intentionally added. However, since trona ash contains NaF, the unit consumption of fluorite is low, making it effective for non-rich ash.

In this case, it is preferable to use the solvent for particles with a particle diameter of about 200 pm, for example. 1- as a solvent is #pig 1
It has been confirmed that the performance of dephosphorization and desulfurization for 1 minute with 10 to 20 kg of +W per ton is poor, and the properties of the obtained slag are also good.

Historically, it is easier to handle than soda ash, which has a high purity and is less hygroscopic.

In addition, for example, oxides such as iron oxide, manganese, chromium, nickel, vanadium, niobium, lithium, etc.
The effect is even more remarkable when one or more of these are added to the solvent a little earlier.

As explained in 1-1 above, the refining slave solvent and the method using the same according to the present invention are cheaper than the conventionally known extremely highly refined soda ash and the refining method using soda ash. Since trona ash is used as a raw material, it has great economic advantages, for example, costs can be reduced by 30% or more, and the actual operating costs are almost the same as when using soda ash.

Claims (1)

[Scope of Claims] (1) A scouring solvent characterized in that the main component is calcined trona ash. 2. Add 10 to 20 kg of a solvent mainly composed of calcined trona ash into the hot metal and stir it,
A method of using a refining solvent characterized by dephosphorizing and desulfurizing hot metal. 3. The method of using a refining solvent as set forth in claim 2, which comprises adding an oxide to the solvent and adding it into hot metal and stirring.