Foamed ball for producing foam slag in process of stainless steel smelting by an electric arc furnace and a manufacture method thereof

Abstract

The invention provides a foaming ball for producing foam slag in the process of stainless steel smelting by an electric arc furnace and a manufacture method thereof. The foamed ball is a hot pressed pellet consisting of iron oxide pieces or powder, coke powder, wasted steel cuttings, iron powder, and wasted plastic crumbles as main materials; The exterior of the pellet is covered by a hard layer comprising a raw material of cement clinker or cement. The manufacture method includes the following steps of: well mixing main materials, and dry materials of the adhesive; adding water to bond the materials; performing hot pressing and pelletization for 0.5-1 hours and mixing the pellets with the cement clinker to enable the surface of the pellets to be covered by the cement clinker slurry; and performing secondary pelletization, airing and baking the pellets. The foaming ball produced by the invention has good strength, such that the foaming ball is not easily broken when falling off from an elevated bunker in the process of stainless steel smelting by an electric arc furnace. Furthermore, the pellet can also produce good foam slag which has a foaming height of over 10cm on average and a foaming time of over 8 min for one time material feeding.The foaming ball can protect electric arc, improve thermal efficiency of the electric arc, reduce power consumption, shorten smelting time and protect the furnace lining.

Description

technical field [0001] The invention relates to the field of electric furnace smelting stainless steel, and relates to a foaming ball used for forming foam slag in the process of electric furnace smelting stainless steel and a manufacturing method thereof. Background technique [0002] The electric arc furnace steelmaking process mainly relies on arc heating. During the smelting process, foaming slag can be used to wrap the arc to absorb more arc energy and reduce arc radiation to the furnace lining. In the actual application process, it can reduce power consumption and fire resistance. Material consumption and other effects, because more arc energy enters the molten pool formed by molten steel and slag, the melting speed can be accelerated, the smelting cycle can be reduced correspondingly, and the production efficiency is improved. [0003] EAF smelting foam slag technology is widely used in EAF smelting of ordinary carbon steel and low alloy steel. It mainly relies on CO ...

AI Technical Summary

Problems solved by technology

[0005] Chinese patent CN101096717 provides a method for generating foamy slag of stainless steel mother liquor smelted by adding dephosphorized hot metal in an electric furnace. Carbon powder is sprayed after the molten pool in the furnace is basically formed, and ferrosilicon powder is sprayed according to the viscosity of the slag to reduce Cr in the slag. 2 o 3 content in order to reduce its viscosity, because it is difficult to control the carbon powder to penetrate the slag layer and not enter the molten steel during the carbon powder injection process, in most cases, the carbon powder stays on the upper part of the slag layer, and the CO gas produced Short residence time, resulting in limited foaming effect of slag

[0007] Korean patent KR970005198 (B1) provides a method of adding manganese ore to slag to make foam slag. The addition of manganese ore can improve the foamability of slag. However, in the process of stainless steel smelting, the reason why it is difficult to make foam slag in stainless steel smelting is the lack of gas source. Slag foaming, this method is difficult to provide enough gas source to ensure good slag foaming effect

[0008] European patent EP1087024 (A1) provides powdery dry ice (ie CO 2 Ice cube) is used as a foaming agent to realize foaming slag in the smelting process of low alloy steel and stainless steel. However, dry ice releases too much gas in the high temperature melting pool, which is easy to cause large splashes and even slag.

[0009] Chinese patent CN101096734 provides an electric arc furnace smelting stainless steel mother liquid steel slag foaming agent, the foaming agent of this invention has quicklime and dolomite and is equipped with Al 2 o 3 , quicklime and dolomite can be decomposed to generate the gas source required for foaming slag, Al 2 o 3 It can lower the melting point of steel slag, and thus create foam slag in the stainless steel smelting process. However, the addition of limestone and raw dolomite will further increase the viscosity of the slag, and the slag may harden. At the same time, after the surface layer of limestone and raw dolomite is decomposed, the SiO 2 Reacts with CaO to form a hard layer, leading to the decomposition of limestone and raw dolomite to produce CO 2 The rate is slow, and by the end of smelting, it cannot effectively produce good foamy slag

[0013] The pellets or briquettes involved in the patents WO2008095575A1, WO2004104232A1 and WO 2010003401 have no strength requirements, and the single foaming time is short. In the actual application process, it is necessary to add new equipment to ensure continuous addition, so as to maintain relatively high Long foaming time, obviously, adding new equipment to the electric furnace not only has high investment cost, but also is installed near the electrode, which is inconvenient to use

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