Electrolyte Crust Plasma Cutting to Prevent Melt Contamination

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Solution Overview

Problem

Existing methods for breaking the electrolyte crust in aluminum reduction cells are inefficient, leading to the formation of solid crust pieces that contaminate the melt, increase energy consumption, and reduce productivity, as they often require extensive time and resources to remove and re-melt, and are not effectively applicable to all areas of the reduction cell.

Innovation Solution

The method employs a directed thermal plasma jet to break the electrolyte crust through separation cutting, where a high-speed, high-temperature plasma jet is used to melt and evaporate the crust material, creating a slit that allows continuous removal of the molten material, thereby minimizing the formation of solid pieces and optimizing energy use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If impact mechanisms are used to break the electrolyte crust, then the crust can be broken effectively, but the device structure becomes complex and immobile

Engineering Contradiction:
Improvecrust breaking efficiencyVSAvoiddevice structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical impact mechanisms with a thermal plasma jet system. The plasma jet melts and removes crust material through thermal energy rather than mechanical impact, eliminating complex mechanical structures while maintaining effective crust breaking capability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the physical state and parameters of the crust by applying high-temperature plasma. The crust transitions from solid to molten state through thermal heating, allowing easy removal without mechanical impact forces

Inventive Principle:
Principle #35Parameter changes

2Productivity

If pneumatic cylinders with breakers are used, then the crust can be broken at specific points, but the method is immobile and only effective at installation points

Engineering Contradiction:
Improvecrust breaking effectivenessVSAvoidmobile arrangement
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The plasma jet system is designed to be universally applicable across different locations on the reduction cell. The portable plasma generator can be moved to any position around the cell, making the system adaptable to various crust formation points without fixed installation requirements

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If vibrohammers are used to break the crust, then the crust can be broken, but the process takes too long

Engineering Contradiction:
Improvecrust breaking capabilityVSAvoidcrust breaking time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The plasma jet induces rapid phase transition of the crust material from solid to liquid state through intense thermal heating. This phase change occurs much faster than mechanical vibration can fracture the crust, dramatically reducing the time required for crust removal

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The plasma jet operates in continuous or pulsed modes, delivering sustained thermal energy to the crust. This continuous thermal action is more efficient than periodic mechanical impacts, achieving faster crust removal

Inventive Principle:
Principle #19Periodic action

4Productivity

If impact forces are applied to break the crust, then the crust can be broken, but solid crust pieces form and contaminate the melt

Engineering Contradiction:
Improvecrust breaking efficiencyVSAvoidcrust pieces contamination
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

By heating the crust to melting point, the plasma jet transforms solid crust into liquid form that can be smoothly removed and re-melted in the electrolyte, preventing the formation of solid contaminating pieces that would result from mechanical impact

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The invention changes the temperature parameter of the crust significantly, raising it above the melting point. This parameter change alters the material behavior from brittle solid to viscous liquid, enabling clean removal without fragmentation

Inventive Principle:
Principle #35Parameter changes

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 power consumption, minimizes the amount of recycled raw materials, and enhances the efficiency of the reduction cell by preventing crust pieces from falling into the electrolyte melt, thus improving both technical and economic characteristics.

Implementation Method 1

a directed jet of thermal plasma is used to break the electrolyte crust

Methodology Applied
Scientific EffectThermal plasma: Plasma

Implementation Method 2

thermal melting a crust material with a high-speed high-temperature concentrated flow of thermal plasma jet heat energy

Methodology Applied
Scientific EffectThermal melting: Melting

Implementation Method 3

a formed molten material is continuously removed from a zone of the thermal plasma jet impact to create in the electrolyte crust a slit

Methodology Applied
Scientific EffectDynamic flow removal: Jet

Data Source

PatentEP3553206B1Method for breaking electrolyte crust by plasma cutting
Publication Date: 2022.08.03 OBSHCHESTVO S OGRANICHENNOY OTVETSTVENNOSTYU OBEDINENNAYA KOMPANIYA RUSAL INZHENERNO TEKHNOLOGICHESKIY TSENTR
  • EP3553206B1 patent drawingFigure 1
  • EP3553206B1 patent drawingFigure 2~3

AI summary

The invention relates to the field of aluminium production, more particularly to breaking electrolyte crust in electrolysers of any type. According to the proposed method, breaking the electrolyte crust in an aluminium electrolytic cell by cutting comprises breaking the crust material by thermal melting thereof using a high-speed, high-temperature concentrated thermal energy flow of a thermal plasma jet, which is accomplished by generating a directed thermal plasma jet and moving same along a pre-set trajectory above the electrolyte crust, continuously removing the resulting melted material from the zone impinged by the thermal plasma jet, and creating with the thermal plasma jet a split in the electrolyte crust sufficient to allow the subsequent cutting of the crust and breaking thereof. The technical result makes it possible to reduce the volume of broken electrolyte crust, to eliminate the formation of lumps of electrolyte crust during breaking of the crust, and consequently to reduce the energy required to heat the covering material consisting of a mixture of alumina and crushed electrolyte which is used to form an electrolyte crust.