TECHNICAL FIELD

The disclosure relates to the technical field of fine chemicals, and more specifically to a production device and production method of electronic grade hydrofluoric acid.

BACKGROUND

Electronic grade hydrofluoric acid is an inorganic acid with weakly acidic, colorless and transparent liquid under room temperature. It is volatile and has a strong pungent odor. The strong corrosiveness makes it one of the key basic chemical materials in the microelectronics industry. The purity and cleanliness of the electronic grade hydrofluoric acid have a very important impact on the yield, electrical performance and reliability of integrated circuits. According to statistics from the International Semiconductor Industry Association (SEMI), by 2020, 62 new wafer fabs will be built globally, of which 26 are in China, accounting for 42%. The global semiconductor production capacity is gradually shifting to China. The rapid development of downstream semiconductors, liquid crystal panels, and crystalline silicon solar energy will drive the demand growth for electronic grade hydrofluoric acid. It is conservatively estimated that the annual demand for electronic grade hydrofluoric acid used in the semiconductor industry will reach 40,000 tons.

The key to the preparation of electronic grade hydrofluoric acid is to control the required content and cleanliness of alkali metal, heavy metal and non-metal impurity ions. Currently, the commonly used technologies for preparing high-purity hydrofluoric acid in China and abroad include rectification, sub-boiling distillation, vacuum distillation, gas absorption and other technologies. These technologies have their own characteristics and strengths. For example, gas absorption technology can be used for large-scale production, while sub-boiling distillation technology can only be used to prepare a small number of products, and the production methods in the prior art may introduce new impurities, or have low yields, or high production costs.

It is difficult to meet industrial needs, and the waste produced during the production process pollutes the environment, and the disposal of the waste increases the production cost.

Therefore, providing a low-cost, high-efficiency, environmentally-friendly, high-purity electronic grade hydrofluoric acid production method is an urgent problem to be solved by those skilled in the art.

SUMMARY

For the reasons above, the disclosure provides a production device and production method of electronic grade hydrofluoric acid. At the same time, the byproducts are applied to the preparation of industrial grade hydrofluoric acid, without introducing additional impurities. The electronic grade hydrofluoric acid products have high yield, good quality and low cost, and the hydrogen fluoride gas is recovered in the tail gas.

In order to achieve the above objectives, the disclosure adopts the following technical solutions.

A production device of electronic grade hydrofluoric acid is provided. The production device includes a purification system. The purification system includes a raw material tank, an evaporator with an inlet connected to a bottom of the raw material tank, a purification tower with a bottom connected to an outlet of evaporator, an absorption tower with a bottom connected to a top of the purification tower, an absorption tower kettle storage tank connected to a bottom of the absorption tower. A bottom of the absorption tower kettle storage tank is sequentially connected to a first delivery pump, an ultrapure filtration device and a filling device. A raffinate storage tank is connected to a bottom of the purification tower.

Further, the production device of electronic grade hydrofluoric acid includes a reabsorption system. The reabsorption system includes a second delivery pump and a first cooler connected sequentially. The second delivery pump is connected to the bottom of the absorption tower kettle storage tank. The first cooler is connected to a top of the absorption tower.

Further, the production device of electronic grade hydrofluoric acid includes a first tail gas absorption system. The first tail gas absorption system includes a first tail gas absorption tower, a first tail gas absorption tower kettle storage tank and a third delivery pump connected sequentially. The first tail gas absorption tower is connected to the tops of the raw material tank and the absorption tower. The third delivery pump is connected to the absorption tower kettle storage tank.

Further, the first tail gas absorption system includes a fourth delivery pump and a second cooler connected sequentially. The fourth delivery pump is connected to the first tail gas absorption tower kettle storage tank. The second cooler is connected to the first tail gas absorption tower.

Electronic grade desalinated water is used in the first tail gas absorption tower to absorb hydrogen fluoride tail gas, and the generated liquid phase is used as the absorbent in the absorption tower.

The above-mentioned further solutions have the beneficial effects that the tail gas in the process is effectively treated, and environmental pollution and resource waste caused by discharged tail gas are avoided.

Further, the production device of electronic grade hydrofluoric acid includes a raffinate treatment system. The raffinate treatment system includes a Venturi ejector, a third cooler, a hydrofluoric acid cycle storage tank, and a fifth delivery pump connected sequentially. The Venturi ejector is connected to the raffinate storage tank. The fifth delivery pump delivers the processed hydrofluoric acid to an industrial grade hydrofluoric acid storage device.

Further, the raffinate treatment system includes a sixth delivery pump connected to the hydrofluoric acid cycle storage tank. The sixth delivery pump is connected to the Venturi ejector.

Further, the raffinate treatment system includes a second tail gas absorption system. The second tail gas absorption system further includes a second tail gas absorption tower, a second tail gas absorption tower kettle storage tank and a seventh delivery pump connected sequentially. The second tail gas absorption tower is connected to a top of the hydrofluoric acid cycle storage tank. The seventh delivery pump is connected to the hydrofluoric acid cycle storage tank.

Further, the second tail gas absorption system includes an eighth delivery pump and a fourth cooler connected sequentially. The eighth delivery pump is connected to the second tail gas absorption tower kettle storage tank. The fourth cooler is connected to the second tail gas absorption tower.

Among them, electronic grade desalinated water is used in the second tail gas absorption tower to absorb the hydrogen fluoride tail gas, and the absorbed liquid phase is transported to the hydrofluoric acid cycle storage tank used as the diluted absorption liquid of hydrogen fluoride.

A production method of electronic grade hydrofluoric acid is provided. The production method includes:

(1) rectification:

transporting an industrial grade anhydrous hydrofluoric acid to the raw material tank, pressurizing the industrial grade anhydrous hydrofluoric acid to 1-10 atm by a compressed nitrogen in the raw material tank, transporting the pressurized hydrofluoric acid to the evaporator for gasification, the gasified hydrogen fluoride entering the bottom of the purification tower;

processing, by the purification tower, the gasified hydrogen fluoride and obtaining high purity hydrogen fluoride gas on top of the purification tower, entering the high purity hydrogen fluoride gas into the absorption tower;

discharging the industrial grade hydrofluoric acid from the bottom of the absorption tower into the raffinate storage tank, processing the discharged industrial grade hydrofluoric acid containing in the raffinate storage tank by the raffinate treatment system, and obtaining an industrial grade hydrofluoric acid;

(2) absorption:

entering the high purity hydrogen fluoride gas into the absorption tower from the bottom of the absorption tower, filling 30% wt-95% wt of liquid phase hydrofluoric acid into the top of the absorption tower, discharging the tail gas from the top of the absorption tower into the first tail gas absorption system for processing after a mass transferring through contacting, and entering the transferred hydrofluoric acid from a bottom output of the absorption tower to the absorption tower kettle storage tank;

(3) ultrapure filtration or reabsorption:

measuring a concentration of the hydrofluoric acid entering the absorption tower kettle storage tank, pumping the hydrofluoric acid into the ultrapure filtration device through the first delivery pump when a concentration of 50% wt is reached, obtaining an electronic grade hydrofluoric acid after being processed by the ultrapure filtration device, transporting the electronic grade hydrofluoric acid to the filling device for storage, reabsorbing the hydrofluoric acid, by the reabsorption system, and returning to the absorption tower for processing when a concentration of the hydrofluoric acid is less than 50% wt.

Further, the processing of the raffinate treatment system in the step (1) includes:

(1.1) Venturi ejector absorption;

transporting the hydrogen fluoride in the raffinate storage tank to the Venturi ejector; diluting and absorbing the hydrogen fluoride in the raffinate storage tank by the 30% wt-90% wt hydrofluoric acid liquid in the Venturi ejector;

(1.2) cooling, by the third cooler, the hydrogen fluoride absorbed by the Venturi ejector and transporting the cooled hydrogen fluoride to the hydrofluoric acid cycle storage tank;

(1.3) storage or recycle;

measuring the concentration of the hydrofluoric acid entering into the hydrofluoric acid cycle storage tank;

transporting, by the fifth delivery pump, the hydrofluoric acid in the hydrofluoric acid cycle storage tank defined as a finished industrial grade hydrofluoric acid to the industrial grade hydrofluoric acid storage device for storage when a concentration of 55% wt is reached;

pumping, by the sixth delivery pump, the hydrofluoric acid in the hydrofluoric acid cycle storage tank to the Venturi ejector when a concentration of the hydrofluoric acid is less than 50% wt and absorbing, by the Venturi ejector, the pumped hydrofluoric acid continually; entering the tail gas discharged from the top of the hydrofluoric acid cycle storage tank into the second tail gas absorption system, and processing the tail gas.

Compared with the prior art through the above technical solutions, the disclosure provides a production device and production method of electronic grade hydrofluoric acid. The purification process is reduced by using Class II superior grade industrial anhydrous hydrofluoric acid as the raw material. During the production of electronic grade hydrofluoric acid, a very small amount of hydrogen fluoride that has not been dissolved and absorbed by the desalinated water is recovered by the secondary absorption of high purity desalinated water to improve the utilization rate of hydrogen fluoride. No waste gas in the production of hydrofluoric acid. During the production of electronic grade hydrofluoric acid, the process is physical mixing without chemical reaction. All the water for producing in the project enters the product, and no wastewater is produced. The annual production scale of electronic grade hydrofluoric acid produced by the technical scheme of the disclosure reaches 25000 tons of EL-grade hydrofluoric acid, 5000 tons of UPS-grade hydrofluoric acid. And byproduct industrial grade hydrofluoric acid reaches 7750 tons of per year. The technical scheme has high economic benefits and environmental protection significance.

