Pre-formed Refractory Plug for Slag Drain Corrosion

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Solution Overview

Problem

The high FeO content in slag causes aggressive corrosion of refractory linings in metallurgical vessels, leading to frequent maintenance and significant downtime, especially in the slag drain channels, which are difficult to maintain without shutting down the vessel.

Innovation Solution

A pre-formed refractory plug with similar corrosion-resistant properties to the surrounding lining is placed at the inlet end of the slag drain channel, reducing corrosion and allowing for maintenance without shutting down the vessel, and a method to increase pressure temporarily to facilitate refractory repair without draining the molten metal and slag.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the slag drain channel is sealed with traditional plugging material, then the slag drain can be maintained, but the refractory lining suffers aggressive corrosion and requires frequent shutdowns for repair

Engineering Contradiction:

Improverefractory lining durabilityVSAvoidvessel downtime

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the material parameter of the plug from traditional plugging material to pre-formed refractory material with similar composition to the surrounding lining. This parameter change reduces chemical incompatibility and aggressive corrosion, extending refractory life and reducing shutdown frequency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite refractory material that matches the surrounding lining composition. This composite approach ensures chemical compatibility and uniform corrosion resistance throughout the slag drain channel, preventing the funnel-shaped corrosion pattern that occurs with traditional plugging materials

Inventive Principle:

Principle #40Composite materials

2Ease of repair

If the vessel is shut down to maintain the slag drain, then the refractory can be repaired, but production stops and external molten metal supply is required

Engineering Contradiction:

Improveslag drain accessibilityVSAvoidcontinuous operation capability

Core Design Contradiction:

Ease of repairVSProductivity

Solution Approach 1:

The patent applies preliminary action by pre-forming the refractory plug before installation. This pre-prepared plug can be quickly installed during brief maintenance windows without requiring full vessel shutdown, enabling rapid repair and minimizing production interruption

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The pre-formed refractory plug acts as a sacrificial protective element that can be replaced relatively quickly compared to full refractory lining replacement. This disposable-like approach allows maintenance without prolonged shutdowns, as the plug protects the main lining during service and can be swapped during brief maintenance periods

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If traditional plugging material is used in the slag drain channel, then the channel can be sealed, but funnel-shaped corrosion patterns develop and refractory life is reduced

Engineering Contradiction:

Improveplug installation simplicityVSAvoidrefractory service life

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical composition parameter of the plug material to match the surrounding refractory lining. This parameter alignment prevents galvanic and chemical corrosion mismatches, eliminating funnel-shaped corrosion patterns and extending uniform service life across the entire slag drain channel

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent achieves homogeneity by using refractory material with similar composition throughout the slag drain channel. This homogeneous material selection ensures uniform corrosion resistance and thermal properties, preventing localized corrosion patterns and extending overall refractory life

Inventive Principle:

Principle #33Homogeneity

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

This approach reduces refractory corrosion, minimizes vessel downtime, and allows for continuous operation during maintenance, extending the refractory life and reducing the need for external molten metal supply for restarting the process.

Implementation Method 1

A pre-formed refractory plug, similarly resistant to corrosion by the molten slag as the surrounding refractory lining, is located in an inlet end of the channel

Methodology Applied

Scientific EffectCorrosion resistance:

Implementation Method 2

increasing a pressure in the vessel to cause molten metal to flow from the vessel into the forehearth to further decrease the metal level in the vessel

Methodology Applied

Scientific EffectPressure-driven flow: Pressure Gradient

Data Source

PatentUS10781497B2Method of sealing and repairing a refractory tap hole

Publication Date: 2020.09.22 TATA STEEL LTD

AI summary

A method of sealing a slag drain in a direct smelting vessel is disclosed. Also disclosed are a method of maintaining a slag drain channel and a direct smelting vessel with a slag drain channel that extends through a sleeve of refractory material installed in the direct smelting vessel. The method for sealing the slag drain includes locating a pre-formed refractory material at an inlet end of the slag drain channel so that it is exposed to a molten bath contained within the direct smelting vessel and sealing the slag drain channel with sealing material downstream of the pre-formed refractory material.