MVR system for separation and purification of sodium sulfate and lithium sulfate from lithium battery wastewater with a processing capacity of 10t/h

In the production and recycling of lithium-ion battery cathode materials, mixed wastewater rich in sodium sulfate and lithium sulfate is generated. This wastewater has a complex composition and high salt content, and traditional treatment methods often only allow it to be disposed of as hazardous waste, which is not only costly but also results in a significant waste of sodium and lithium resources. Faced with the urgent need for sustainable development in the lithium battery industry and increasingly stringent environmental regulations, a well-known lithium battery material manufacturer commissioned Conqinphi to design and build an industrial-grade solution capable of simultaneously recovering high-purity sodium sulfate and lithium sulfate from wastewater.

I.Core System Advantages

1.Process Design

Based on the phase equilibrium theory of the sodium sulfate-lithium sulfate-water ternary system, Conqinphi developed a unique "thermal separation" process. By precisely controlling the evaporation temperature curve and crystallization path, the system guides the saturated precipitation of sodium sulfate and lithium sulfate at different stages, fundamentally solving the problem of separating two common ionic salts.

2.Multi-stage Crystallization Coupling Technology

The system innovatively couples evaporation crystallization with cooling crystallization. First, preferential crystallization separation of sodium sulfate is achieved in the high-temperature zone, followed by directional crystallization of lithium sulfate through temperature-controlled cooling. This graded crystallization strategy ensures high-purity production of both products.

3.Dynamic Concentration Control System: Equipped with an online density meter, conductivity meter, and chemical analyzer, the system monitors changes in system composition in real time and automatically adjusts evaporation intensity and cooling rate to ensure the system always operates within the optimal separation range, effectively preventing eutectic phenomena.

4.Product Refinement Processing Unit: Subsequent processing technologies are designed to address the different characteristics of the two salts: sodium sulfate undergoes high-temperature dehydration to obtain anhydrous product; lithium sulfate is purified through recrystallization to obtain battery-grade product. This differentiated refinement process significantly enhances the market value of the products.

5.Intelligent Anti-Eutectic Mechanism: The system incorporates artificial intelligence algorithms that utilize machine learning of historical operating data to predict and proactively avoid eutectic regions, automatically adjusting operating parameters to ensure continuous optimization of separation efficiency.

II.Technological Innovation Highlights

1.Directed Crystallization Technology: By adding specific crystal-directing agents, lithium sulfate is controlled to precipitate in a specific crystal form, significantly improving product purity and crystal quality.

2.Mother Liquor Purification Circuit: A dedicated mother liquor purification unit is set up to effectively control impurity accumulation and ensure long-term stable operation of the system.

3.Energy Cascade Utilization: The latent heat of vaporization is innovatively used for subsequent drying processes to maximize energy utilization.

4.Online Cleaning System: Cleaning schemes are designed for different crystallization stages to ensure that each unit always maintains optimal operating conditions.

III.Project Achievements and Value Creation

Since its commissioning, the system has achieved significant results:

1.Resource recovery benefits: Annual recovery of 3,000 tons of battery-grade lithium sulfate and 8,000 tons of industrial-grade anhydrous sodium sulfate, transforming a wastewater treatment cost center into a profit center.

2.Environmental benefits: Achieving near-zero wastewater discharge, reducing hazardous waste generation by approximately 12,000 tons annually.

3.Product value: Lithium sulfate products meet battery-grade standards, and sodium sulfate meets first-class industrial standards, significantly increasing product value.

4.Operational efficiency: The system is highly automated, requiring only two operators per shift, and reducing overall operating costs by 40% compared to traditional methods.

IV.Technological Outlook:

The successful implementation of this project sets a new technological benchmark for wastewater resource utilization in the lithium battery industry. Conqinphi is further optimizing this technology and plans to extend it to separation scenarios in other mixed salt systems, providing solid technical support for promoting the green and sustainable development of the new energy industry.