Pickling tank

▍ Working principle

The working principle of a pickling tank is relatively simple and direct. Its core function is to safely hold and contain acidic chemical liquids, providing a reaction space for workpieces (such as metal parts, semiconductor silicon wafers, etc.) to soak, clean, corrode, or perform surface treatment.

1. Filling and Immersion: A predetermined concentration and volume of acid (such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, etc.) or mixed acid is injected into the tank.

2. Chemical Reaction: The workpiece to be treated is immersed in the acid solution using hangers or baskets. Within a set immersion time, the acid reacts chemically with oxides (such as rust), oil stains, or specific coatings on the workpiece surface, dissolving or peeling them off.

3. Post-treatment: After treatment, the workpiece is removed for subsequent processes such as washing, neutralization, and drying. Waste acid is discharged into a wastewater treatment system through a pre-installed outlet in the tank.

Throughout the process, the PP material tank acts as a completely inert "barrier," ensuring that the highly corrosive chemical liquid reacts only with the workpiece and does not corrode the equipment itself, guaranteeing the purity and safety of the process.

▍Structural features

The design of PP pickling tanks fully considers strength, durability, and ease of operation, with distinct structural features:

1. Superior Materials:

● Main Material: Utilizes imported or domestically produced high-quality polypropylene (PP) sheets, typically 8mm to 20mm thick, selected based on tank size and load-bearing requirements to ensure sufficient structural strength.

● Welding Materials: Uses PP welding rods with the same composition as the base material, achieving seamless connections through hot-melt welding to avoid electrochemical corrosion caused by material differences.

2. Reinforced Design:

● External Reinforcing Ribs: To prevent tank deformation due to hydrostatic pressure, large pickling tanks typically feature a dense "grid" or "U"-shaped reinforcing rib structure on the exterior. These ribs are also welded from PP sheets, greatly enhancing the tank's resistance to pressure and deformation.

● Tank Edge Embossing: The top edge of the tank is usually thickened and edged, not only for aesthetics but also to increase edge strength, facilitating load-bearing and installation.

3. Multifunctional Accessory Interfaces:

● Drain Port: A drain port is designed at the bottom or side wall of the tank for easy and thorough emptying of waste liquid. It can typically be connected to a pipe valve.

● Overflow Port: Used to control the liquid level or remove surface oil, maintaining a stable liquid level.

● Side Drain: A side drain can be installed as needed to connect to a circulating filtration system, keeping the tank solution clean and of uniform concentration.

● Other Interfaces: Installation interfaces for instruments such as heating elements, temperature sensors, and level gauges can be provided.

4. Optional Configurations:

● Saddle/Bracket: Can be equipped with a PP saddle of the same material or a carbon steel bracket with a PP/PVC outer sheath to ensure stable placement of the equipment.

● Cover: Can be equipped with a flat or arched cover to reduce acid mist evaporation, provide insulation and dust prevention, or ensure safety.

● Internal Partitioning: Can be designed as a multi-tank or stepped tank for continuous operation.

▍ Scope of application

PP pickling tanks have an extremely wide range of applications, suitable for almost all processes involving acid and alkali treatment:

● Metal surface treatment industry: Used for pretreatment processes such as rust removal, pickling, phosphating, passivation, and oxidation of metals such as steel, copper, and aluminum.

● Electroplating industry: Used as pre-plating pickling and activation tanks, and post-plating cleaning tanks.

● Electronics and semiconductor industry: Used for cleaning and etching silicon wafers.

● Chemical industry: Used as small reaction vessels, mixing tanks, and storage tanks for corrosive chemical media.

● Environmental water treatment industry: Used as tanks for neutralization, flocculation, and sedimentation processes in wastewater treatment.

● Laboratory: Used as corrosion-resistant containers for various chemical reagents.

Precautions: Although PP has broad corrosion resistance, its suitability for specific concentrations and temperatures of chemicals must still be confirmed before use. For example, PP has poor resistance to strong oxidizing acids (such as concentrated nitric acid and chromic acid) and certain organic solvents, requiring special attention.

▍ Summarize:

PP pickling tanks, with their excellent corrosion resistance, robust seamless structure, long service life, and low maintenance costs, have become one of the standard configurations for handling corrosive liquids in modern industry. Choosing a well-designed and well-manufactured PP pickling tank is a key investment to ensure the safe, efficient, and environmentally friendly operation of the production process.