I. Project Background and Core Challenges

A leading domestic rare earth separation technology company, in order to meet the growing international demand for ultra-high purity single rare earth oxides, decided to strategically upgrade its core hydrometallurgical process. While the company's existing production line could operate stably, traditional metal equipment gradually revealed its limitations in long-term corrosion resistance and preventing "secondary contamination" of products when facing extraction and separation purity requirements exceeding 99.99% in strong hydrochloric acid or sulfuric acid environments. The core objective of the production line upgrade was to construct a solvent extraction and separation system that was absolutely stable, absolutely clean, and highly automated in highly corrosive media to meet the stringent raw material requirements of downstream industries such as high-end magnetic materials and phosphors.

II. Innovative Solution: Full-System PVC Rigid Panel Engineering Integration

After rigorous evaluation and demonstration, the project abandoned the traditional metal material solution and creatively proposed a "full-process PVC rigid panel engineering integration" solution. This solution not only replaced the core extraction tank with PVC material but also extended this concept to every stage of the entire process flow.

Core Equipment: Modular PVC Extraction Tank Assembly

The core of the entire extraction system consists of dozens of PVC mixing and clarification extraction tanks connected in series. Each tank is made of industrial-grade rigid PVC sheet with a thickness of over 30 mm, integrally formed through CNC precision cutting and professional hot air welding. The internal design of the tank is extremely precise: the mixing chamber is equipped with a unique PVC baffle system, combined with an adjustable-speed PVC agitator, to achieve extremely gentle mixing of the organic and aqueous phases; the clarification chamber is equipped with a precisely adjustable PVC overflow weir to ensure a clear and stable interface between the two phases. Some key stages even use transparent PVC side panels, allowing operators to directly observe phase changes and achieve visualized process management.

Auxiliary System: Fully Plasticized Piping and Storage Units

To achieve the absolute goal of "zero metal contact," the auxiliary units of the entire system are also fully plasticized. All connecting pipes, valves, and pump flow parts are made of PVC or reinforced PP materials. Large containers, including rare earth liquid storage tanks, hydrochloric acid storage tanks, and organic phase transfer tanks with volumes of several cubic meters, are all fabricated on-site using rigid PVC sheets welded together. Their strength and sealing performance fully meet the requirements of continuous industrial production.

Control System: Intelligent Closed-Loop Management

This physically "pure" equipment system is deeply integrated with an advanced distributed control system. Special interface sensors and online pH monitors installed on the PVC tanks provide real-time data feedback to the central control room. The system can automatically adjust the stirring intensity and precisely control the two-phase flow ratio and acidity, achieving "three constants" intelligent closed-loop operation: constant interface, constant pH value, and constant flow ratio. This elevates the process stability from "human control" to "intelligent control."

III. Operational Results and Comprehensive Benefits

Since the official commissioning of this fully integrated PVC production line, its performance has exceeded project expectations in all aspects, achieving significant technical and economic benefits.

In terms of product quality, the purity of single rare earth products such as praseodymium oxide and neodymium oxide produced by the production line is consistently maintained above 99.995%, with the content of key metal impurities below the detection limits of analytical instruments. This breakthrough quality has enabled the company to successfully enter the global high-end supply chain.

Regarding process and equipment reliability, the superior chemical inertness of PVC material has brought about a fundamental change. The production line has achieved an excellent record of three consecutive years without unplanned downtime, completely eliminating production stoppages and material losses caused by equipment corrosion and leaks. The process is extremely stable, with the total yield of the extraction section consistently exceeding 99.8%, resulting in a qualitative leap in production efficiency.

In terms of economic benefits, the advantages are even more pronounced. First, the initial investment cost of the project is reduced by approximately 35% compared to using high-end corrosion-resistant metal materials. Second, in operation and maintenance, the main body of the equipment eliminates the tedious work of updating anti-corrosion coatings and repairing weld points, and daily energy consumption is also reduced due to low pipeline resistance, resulting in a nearly 25% reduction in overall operating costs. Furthermore, the entire system is leak-free, and the production site is clean and environmentally friendly, significantly reducing safety and environmental management costs. IV. Case Summary and Industry Implications

IV. Case Summary and Industry Implications

The success of this case is not merely a simple material replacement, but a systematic engineering innovation based on a profound understanding of the process. It fully demonstrates that in the traditional heavy industry of hydrometallurgy, the scientific design and precision manufacturing of non-metallic materials can overcome core pain points in high-end manufacturing.

This project provides a highly valuable reference for the rare earth and even the entire non-ferrous metal refining industry: when facing the requirements of high purity, strong corrosion, and long-cycle operation, the PVC rigid board integrated solution demonstrates its overwhelming advantages in economy, reliability, and cleanliness. It is not just an upgrade of a production line, but represents a new path for industrial development that is more cost-effective and sustainable, setting a benchmark for technological progress and cost reduction in the industry.