1. Project background

In recent years, my country's electronics industry has developed rapidly. As the foundation of the electronics industry, the printed circuit board (referred to as PCB) industry has continued to grow at an annual rate of 14.4%. In 2006, China replaced Japan and became the world's largest printed circuit board production base. The annual output value of my country's printed circuit board industry reaches US$29 billion, mainly distributed in the "Yangtze River Delta" and "Pearl River Delta" regions.

A large amount of etching waste containing high concentrations of copper is generated during PCB production. The main component in these etching waste liquids is copper salts, but also contains other inorganic substances, such as ammonia, hydrochloric acid, hydrogen peroxide, sulfuric acid, etc. These components together have an extremely high pollution index and are hazardous liquid waste. At the same time, the concentration of copper ions in etching waste liquid exceeds the standard by several million times, and the potential for resource recovery is huge. At present, my country's average daily production of etching waste liquid exceeds 2000 tons/day, and it still grows at a rate of about 10% every year. Generally speaking, 2 of etching solution is consumed for every 1m2 of circuit boards produced~2.5L, corresponding to 2 etching waste liquid~2.5L, the PCB industry consumes more than 100,000 tons of refined copper every year, while the copper content in etching waste liquid is more than 50,000 tons.

In the actual production process of my country's industry, the current common practice for the treatment of etching waste liquid is to store etching waste liquid in closed storage tanks in each PCB manufacturer and send it to outsourced environmental protection units for treatment. The commonly used waste liquid treatment methods are chemical precipitation method, electrolysis method, extraction method, etc. The copper in the etching waste liquid is prepared into products such as copper sulfate, electrolytic copper plate or copper oxide powder. The products of these treatment methods have low added value and poor economy.

2. technical advantages

Supercritical hydrothermal synthesis reaction refers to the hydrolysis and dehydration reaction of metal salts in a closed high-pressure reactor using supercritical water as the reaction medium, and then nucleate, grow, and finally form nanocrystals with a certain particle size and crystalline morphology. Since the reaction medium is supercritical water, the reaction process is carried out in a closed high-pressure vessel, so no other pollutants will be introduced during the reaction process. It is considered to be a green and environmentally friendly nano-preparation technology.

Using supercritical hydrothermal synthesis method to treat copper-containing waste liquid, the conversion rate of Cu2 + can reach more than 99.8%, and the average particle size of the product can reach 10~20nm。Testing and analysis show that all the products are Cu, and the purity of the product can reach more than 99.9%. In addition, the treated waste liquid can be completely reused to achieve zero discharge of waste liquid.

3. market economic analysis

Taking a system for preparing nano-copper through supercritical hydrothermal synthesis of printed circuit board etching waste liquid with a processing capacity of 10t/d as an example, based on the concentration of Cu2 + in the waste liquid of 120g/L, the equipment investment cost is about 10 million yuan., the operating cost of treating tons of wastewater is 3514 yuan/ton, and the income from treating tons of wastewater is about 360,000 yuan/ton. Based on this estimate, the investment of the entire project can recover all project investment costs within 3 months, and a net profit of approximately 100 million yuan per year can be created every year. Therefore, this technology has strong technical and economic advantages and broad market prospects.

4. main application fields

This technology is suitable for harmless treatment of production wastewater and related fields of resource utilization in printed circuit board factories. The application of this technology has no geographical restrictions.

5. Cooperation conditions requirements

(1) A natural person with the ability to independently bear civil liability or an enterprise legal person who independently bear civil liability.

(2) Carry out industrial demonstration and operation by combining industry, academia and research, and cooperative enterprises need to provide financial and operational support.

(3) Have certain investment capabilities and risk awareness, and have certain market promotion and expansion capabilities.