Breakthrough in Ion Exchange Resin Technology: Zero Sludge Discharge Achieved in Thallium-Containing Wastewater Treatment at Chinese Lead Smelter

Breakthrough in Ion Exchange Resin Technology: Zero Sludge Discharge Achieved in Thallium-Containing Wastewater Treatment at Chinese Lead Smelter

Summary

On March 10, 2025, a Chinese lead smelter achieved zero sludge discharge in thallium-containing wastewater treatment through advanced ion exchange resin technology. By integrating oxidation-precipitation and resin adsorption, the process achieved 98% thallium recovery and eliminated sludge disposal costs, reducing chemical consumption by 30%. This innovation sets a benchmark for heavy metal pollution control and accelerates green smelting under China's dual carbon strategy.

Breakthrough in Ion Exchange Resin Technology: Zero Sludge Discharge Achieved in Thallium-Containing Wastewater Treatment at Chinese Lead Smelter
Breakthrough in Ion Exchange Resin Technology: Zero Sludge Discharge Achieved in Thallium-Containing Wastewater Treatment at Chinese Lead Smelter

1. Technological Breakthrough: From Hazardous Waste to Resource Efficiency
The lead smelter adopted ​RCX-5143 ion exchange resin developed by Kehaisi, optimizing traditional oxidation methods with the following steps :

​Step 1: Potassium permanganate (KMnO₄) oxidizes ​Tl⁺ to Tl³⁺, forming stable ​TlCl₄⁻ complexes.
​Step 2: Selective adsorption of thallium complexes by ion exchange resin, achieving a capacity of ​1.2 g Tl/g resin.
​Step 3: Resin regeneration using sodium sulfite (Na₂SO₃), recovering ​thallium concentrate (purity >99%) with a ​95% reuse rate.

​2. Activated Carbon Synergy: Dual Safeguards for Water Safety
To address complex pollutants, the plant deployed ​coconut shell activated carbon systems (iodine value ≥800), targeting ​organic sulfides and residual chloride ions. Key findings :

​Collaborative Efficiency: Activated carbon-resin integration increased COD removal to ​92%, outperforming standalone methods (activated carbon: 78%; resin: 85%).
​Material Innovation: Spherical activated carbon derived from ​sulfonic acid-based cation exchange resin via ​CO₂ activation exhibits high mechanical strength (compressive resistance ≥50 MPa) and controlled pore distribution (microporosity >70%).