Electric Furnace Shallow Bottom Buffer Zone Slag Foaming

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Solution Overview

Problem

Existing slag treatment methods face inefficiencies due to slag foaming and overflowing issues when molten slag is poured into an electric furnace, leading to reduced productivity and increased energy consumption, particularly because of vigorous mixing with molten iron, which requires repeated adjustments in carbon concentration and treatment processes.

Innovation Solution

An electric furnace design featuring a cylindrical furnace body with a deep and shallow bottom portion, where the shallow bottom portion is positioned to receive the molten slag, preventing direct contact with the molten iron layer and reducing mixing, thereby alleviating foaming through a controlled pouring mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If molten slag is poured directly into the electric furnace, then the treatment efficiency is improved, but slag foaming and overflowing occur due to vigorous mixing with molten iron

Engineering Contradiction:

Improvetreatment efficiencyVSAvoidslag foaming

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a buffer zone as an intermediary layer between the molten slag and molten iron. This buffer zone prevents direct contact and vigorous mixing between the two molten materials, thereby suppressing slag foaming while allowing continuous treatment operations. The buffer zone acts as a mediator that enables the pouring process without causing harmful foaming effects.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the furnace bottom into a deep bottom portion and a shallow bottom portion, creating distinct functional zones. The shallow bottom portion specifically serves as the buffer zone area where molten slag is received before potentially contacting molten iron. This segmentation allows the system to maintain both efficient slag treatment and foam suppression capabilities.

Inventive Principle:

Principle #1Segmentation

2Productivity

If the pouring rate of molten slag is increased to improve productivity, then treatment efficiency is improved, but slag overflowing occurs

Engineering Contradiction:

Improvepouring rateVSAvoidslag overflowing control

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent creates a buffer zone in advance by designing the shallow bottom portion before slag pouring occurs. This pre-established buffer zone provides a cushioning capacity to absorb the incoming molten slag at high pouring rates without causing immediate overflowing. The cushioning effect is built into the furnace structure itself, allowing reliable operation at improved pouring rates.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Object-affected harmful factors

If carbon concentration in the steel bath is reduced to suppress slag foaming, then foaming is reduced, but the reduction treatment of slag becomes less effective

Engineering Contradiction:

Improveslag foaming suppressionVSAvoidreduction treatment effectiveness

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The buffer zone serves as an intermediary that decouples the relationship between slag pouring and molten iron contact. By preventing direct mixing through this intermediate layer, the system suppresses foaming without requiring reduction of carbon concentration in the molten iron. This allows the molten iron to maintain its reducing capability for effective slag treatment while the buffer zone handles the foaming suppression function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design effectively prevents vigorous mixing and foaming, enhancing treatment efficiency by maintaining a stable molten slag layer as a buffer zone, allowing for increased pouring rates without overflowing and improving overall productivity.

Implementation Method 1

electric furnace that is used for a process in which molten slag produced in a steelmaking step is temporarily held in a slag holding furnace while maintaining the molten state thereof

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a molten slag layer is formed as a buffer zone on a molten iron layer in an electric furnace

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentUS11898797B2Electric furnace

Publication Date: 2024.02.13 NIPPON STEEL CORPORATION

AI summary

The present invention provides an electric furnace including: a furnace body that includes an electrode; and a slag holding furnace that is configured to hold molten slag in a molten state and is capable of pouring the molten slag into the furnace body when tilted, in which the furnace body includes a cylindrical furnace wall, a furnace cover that is provided at an upper end of the furnace wall, a furnace bottom that is provided at a lower end of the furnace wall and includes a deep bottom portion and a shallow bottom portion as a region having a height of 150 mm to 500 mm from a deepest point of the deep bottom portion, and a slag pouring port that is provided at the furnace cover and through which the molten slag is poured from the slag holding furnace, the slag pouring port overlaps the shallow bottom portion in a plan view, and the area ratio of the shallow bottom portion to the furnace bottom in a plan view is 5% to 40%.