Design of Acid Regeneration for Waste Acid Etching Liquid
Introduction
Acid etching liquid is a type of liquid solution composed of acids, such as hydrochloric acid, nitric acid and sulphuric acid. It is used in the manufacturing of printed circuit boards (PCBs), coatings, surface treatments, chemical mixtures and etching. The purpose of using this type of acid is to etch away unwanted material, such as impurities, from the material being etched.
However, the use of acid etching liquid produces a large amount of waste liquid which contain large amounts of pollutants, such as metals, fluorides and alkalis. In order to minimise the environmental impact of the waste acid etching liquid, an efficient acid regeneration technology is needed.
Objectives
The objectives of this design are to develop an acid regeneration process to treat and recover the waste acid etching liquid while minimising the environmental damage caused by the disposed acid etching liquid. In addition, the design should reduce the cost of acid regeneration, optimise the treatment efficiency and reduce the amount of waste produced.
Process Description
The acid regeneration process consists of three stages: pre-treatment, filtration and neutralisation.
The pre-treatment stage includes a combination of physical and chemical treatments to remove solids, chlorine volatile compounds and other toxic compounds from the acid etching liquid.
The next step is filtration, which involves using a filter to remove solids, metals and fluorides from the liquid. The filtered material can be reused as a part of the acid regeneration process.
The last step is neutralisation, which involves neutralising the acid by adding alkalis to the solution, such as sodium hydroxide and calcium hydroxide. The neutralised solution can then be reused as part of the acid regeneration process.
Equipment
The acid regeneration process requires the following equipment:
• Clarifier:
This is used to physically separate solids from the liquid.
• Filter:
This equipment is used to separate metals and fluorides from the liquid.
• Mixer:
This equipment is used to mix the alkalis with the acid to achieve neutralisation.
• Neutralising Tanks:
These are used to store the neutralised liquid until it is reused.
• Disposal Tanks:
These are used to store the acid that has been removed from the regeneration process.
Cost Analysis
The cost of the acid regeneration process will vary depending on the type of equipment and materials used. The cost of pre-treatment depends on the amount of physical and chemical treatments needed. The cost of filtration depends on the type of filter and the size of the filter needed for the application. The cost of neutralisation also depends on the amount of alkalis needed.
In addition, the cost of disposal of waste from the acid regeneration process has to be taken into account. Disposal costs include transportation, landfill charges, hazardous waste disposal fees and other expenses related to safely disposing of hazardous waste.
Conclusion
The acid regeneration process is designed to recover the acid etching liquid and reduce its environmental impact. The process consists of three stages: pre-treatment, filtration and neutralisation. Each stage requires different types of equipment, such as clarifiers, filters, mixers and neutralising tanks. The cost of the acid regeneration process depends on the types of equipment and materials used and the cost of disposing of the waste generated by the process.
