RU2260064C1 - Method of refining flux - Google Patents

Abstract

FIELD: special-purpose electrometallurgy; production of fluxes on base of fluorides of alkaline-earth elements for electroslag remelting.

SUBSTANCE: proposed method includes loading the flux or mechanical mixture of its components into water-cooled crystallizer and melting flux or its components. For melting the flux, use is made of steel electrode; at total content of phosphorus in flux components or in flux within 0.02-0.07 mass-%, 0.8-1.0 kg of electrode metal is molten per kg of flux and at content of phosphorus of 0.071-0.13 mass-%, 1.1-1.3 kg of electrode metal is molten.

EFFECT: reduced content of phosphorus and carbon in flux for excluding increased content of these elements in electroslag remelting.

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Description

The invention relates to special electrometallurgy and can be used in the technology for the production of fluxes based on fluorides of alkaline-earth elements used in electroslag remelting of steels and alloys.

A known method of smelting fluxes based on fluorine compounds of alkaline earth elements, including loading the mixture and refining it in an atmosphere of hydrogen fluoride (AS USSR No. 52921, IPC C 21 C 5/54, 09/25/76.).

The disadvantage of this method of smelting fluxes is the need for a special flux-smelting furnace and the presence of phosphorus in the range of 0.02-0.03 wt.%, Polluting the metal during ESR by 0.004-0.006 wt.%.

Closest to the proposed one is a method of smelting flux, which involves loading a mechanical mixture of flux components into a water-cooled crystallizer of an electroslag furnace and melting it with a graphite electrode (Technological Instructions ZMK-EShP “Electroslag Remelting of Steel and Alloys”, Zlatoust, 2001, p.13 p .2.4.5).

The disadvantage of this method of smelting flux is the presence of phosphorus in it to 0.13 wt.% And its saturation with carbon from a graphite electrode. When electroslag remelting of steels and alloys by a known method in the lower part of the deposited ingot, the phosphorus content increases by 0.004-0.012 wt.%, And the carbon content up to 0.03 wt.% Due to their transition from flux.

The objective of the invention is to reduce the flux content of phosphorus and carbon and, as a consequence, to avoid increasing the content of the latter in the metal ESR.

The problem is solved by loading a mechanical mixture of flux components or unrefined flux itself into a water-cooled mold of an electroslag furnace and melting them with a steel electrode. When the total content of phosphorus in the components of the flux or in the flux is 0.02-0.07 wt.% Per 1 kg of flux, 0.8-1.0 kg of electrode metal is alloyed, and when the phosphorus content is 0.071-0.130 wt.% - 1.1 -1.3 kg.

In the refined flux, the phosphorus content should be less than 0.02 wt.%, Otherwise, in the process of electroslag remelting of high-quality and high-quality steel, phosphorus will go from steel to slag.

When the phosphorus content in the unrefined flux or in the components of the flux is 0.02-0.07 wt.%, To obtain phosphorus in the refined flux of less than 0.02%, 0.8-1.0 kg of electrode metal must be fused to 1 kg of flux. When fusing less than 0.8 kg per 1 kg of flux, the degree of dephosphorization is insufficient, and when fusing more than 1 kg of flux, the degree of dephosphorization does not increase, but the consumption of electricity and steel electrode increases. When the phosphorus content in the initial flux or its components is 0.071-0.130 wt.%, To obtain less than 0.02 wt.% In the refined phosphorus phosphorus, 1.1-1.3 kg of the steel electrode must be fused per 1 kg of flux, while fusing less than 1 , 1 kg the degree of dephosphorization is insufficient, and when fusing more than 1.3 kg, the degree of dephosphorization does not increase, while the consumption of electricity and steel electrode increases unjustifiably.

At Zlatoust Metallurgical Plant OJSC, work was carried out in which it was experimentally established that the kinetics of the flux dephosphorization process is described by a first-order equation with a mass transfer coefficient of 0.0023 1 / s. The distribution coefficient of phosphorus between flux and metal is 0.95. Based on the established dependencies, the proposed method was developed.

Testing was carried out by refining an experimental flux brand ANF6. A mixture of flux components — calcium fluoride (CaF ₂ ) and alumina (Al ₂ O ₃ ) was loaded into a water-cooled copper of the OKB 905 electroslag furnace. The flux was melted using a metal electrode made of technical iron. After melting the flux, a part of the electrode was fused. The metal of the electrode, passing through the flux, refines it from phosphorus. The phosphorus content increases from 0.008-0.011 wt.% In the electrode to 0.03-0.13 wt.% In the alloyed metal. The remelted part of the metal was transferred to the charge. The flux was cooled, crushed and used for electroslag remelting.

The results of testing are shown in tables 1 and 2, from which it is seen that the declared mass limits of the fused steel electrode, depending on the phosphorus content in the flux components, make it possible to obtain a phosphorus content in the refined flux of not more than 0.02 wt.% (Table 1). ESR of steels and alloys on refined flux does not lead to an increase in the content of P and C in the ESR metal relative to the initial metal (Table 2).

Thus, the proposed technology of refining flux allows you to get refined fluxes with a phosphorus content of less than 0.02 wt.%, Which can be used in the production of high-quality and high-quality steels and alloys by electroslag remelting. To reduce costs, technological waste from crimping mills can be used as steel electrodes.

Table 1. No. The phosphorus content, wt.% The mass of the fused electrode, kg Flux weight (kg) The mass of the fused electrode per 1 kg of flux, kg in the electrode in flux components before refining in refined flux 1 0.008 0.016 0.015 120 200 0.6 2 0.008 0.02 0.019 120 200 0.6 3 0.008 0.02 0.012 160 200 0.8 4 0.008 0,055 0.013 180 200 0.9 5 0.008 0,07 0.013 200 200 1 6 0.008 0,07 0.013 250 200 1.25 7 0.008 0,072 0.013 110 100 1,1 8 0.008 0.11 0.014 120 100 1,2 nine 0.008 0.13 0.016 130 100 1.3 10 0.008 0.13 0.016 150 100 1,5 eleven 0.008 0.136 0.017 150 100 1,5

Table 2. No. steel grade The phosphorus content in refined flux,% The phosphorus content, wt.% Carbon content, wt.% in the electrode in metal ESR in the electrode in metal ESR 1 18 × 2nva-sh 0.008 0.007 0.006 0.16 0.16 2 12 × n3a-sh 0.008 0.007 0.007 0.14 0.13 3 Ei835-w 0.01 0,022 0.02 0.09 0.09 4 40 × N2mAh 0.01 0.009 0.009 0.4 0.41 5 O × n3ma-sh 0.01 0.011 0.1 0.36 0.36

Claims (1)

A method of refining a flux, comprising loading a flux or a mechanical mixture of its components into a water-cooled crystallizer, melting the flux or its components, characterized in that the flux is melted with a steel electrode, with a total content of phosphorus of 0.02-0.07 in the flux components or in the flux wt.% per 1 kg of flux alloy 0.8-1.0 kg of electrode metal, and with a phosphorus content of 0.071-0.13 wt.% - 1.1-1.3 kg of metal electrode.