Waste lithium battery recycling, pyrolysis, and incineration treatment process and oxygen content control objectives

I. Brief description of the current treatment process

Pretreatment stage

Discharge treatment Thoroughly discharge the waste lithium batteries to prevent short circuits or explosions during subsequent processing.

Physical disassembly and sorting Separate components such as the shell, diaphragm, and electrode materials through methods such as crushing, screening, and magnetic separation.

Enrichment of active substances Separate the positive and negative electrode materials (such as lithium cobaltate, ternary materials) from metals such as copper and aluminum foil.

Pyrolysis and incineration stage

High-temperature pyrolysis Heating in an oxygen-deficient or low-oxygen environment (usually 500–800°C) causes the organic electrolyte, binder (such as PVDF), and diaphragm to volatilize and decompose into combustible gas and coke, avoiding complete oxidation.

Incineration treatment High-temperature incineration (>1000°C) of the pyrolysis residue under oxygen-rich conditions to completely decompose residual organic matter and melt metal components for subsequent recovery.

Flue gas treatment system

Rapid cooling and dust removal Rapidly reduce the temperature to prevent the resynthesis of dioxins, and remove particulate matter using bag dust removal or electrostatic precipitators.

Gas purification Using wet scrubbing (such as alkali solution absorption of HF, HCl), activated carbon adsorption (removal of dioxins), and SCR/SNCR denitrification (control of NOx).

Metal recovery

The ash after incineration is extracted for valuable metals such as cobalt, nickel, and lithium through hydrometallurgy (acid leaching, extraction) or pyrometallurgy (smelting).

II. Core objectives of oxygen content control

Optimize combustion efficiency and energy utilization

Real-time monitoring of flue gas oxygen concentration using a zirconia oxygen analyzer, dynamically adjusting the oxygen supply to maintain the optimal air-fuel ratio, ensuring complete combustion of organic matter, reducing CO and unburned hydrocarbon emissions, and avoiding energy waste caused by excessive oxygen.

Inhibit the generation of pollutants

Dioxin control Maintain high temperature (>850°C) and sufficient oxygen during the incineration stage to ensure complete decomposition; strictly control the oxygen content (<6%) during the flue gas cooling stage to avoid low-temperature resynthesis.

Reduce NOx generation Reduce the generation of thermal NOx through staged combustion (oxygen-deficient zone inhibits NOx formation, oxygen-rich zone completes combustion).

Ensure process safety

Avoid excessive oxygen in the pyrolysis stage causing violent oxidation reactions of the electrolyte or binder, leading to a sudden increase in furnace pressure or explosion risk.

Improve metal recovery quality

Precisely control the oxygen concentration in the incineration furnace (usually 2–5%) to prevent excessive oxidation of metal components (such as cobalt and nickel) to form difficult-to-treat oxides, affecting the efficiency of subsequent hydrometallurgical leaching.

III. The key role of the zirconia oxygen analyzer

This instrument is based on the principle of solid electrolyte (zirconia conducts oxygen ions at high temperatures). By measuring the difference in oxygen partial pressure between the flue gas and the reference gas, it provides real-time feedback of the oxygen concentration signal to the control system, ensuring that the process is always in the optimal oxygen content range. It has high precision (±0.1% O₂) and high-temperature resistance, suitable for the harsh working conditions of pyrolysis and incineration.

Summary Oxygen content control is a core link in the pyrolysis and incineration process of waste lithium batteries, directly affecting pollution reduction, energy efficiency, and resource recovery rate, while the zirconia oxygen analyzer is a key monitoring method for achieving this goal.