Surface cleaning with acid is the process of cleaning impurities such as rust and metal oxide on metal surfaces with strong mineral acids called surface cleaning solutions. Hydrochloric acid and Sulfuric acid are commonly used acids. Phosphoric, Hydrofluoric or Nitric acid is also used. Sulfuric or Hydrochloric acids are used for surface cleaning of carbon steel. Phosphoric, Nitric and Hydrofluoric acids are used together with Sulfuric acid for surface cleaning of stainless steel. ​

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Waste acid is disposed of by the methods specified in the 1st and 2nd articles below or recovered.

1. Offsite disposal

2. Sending to waste water treatment plants after neutralization and clarification processes within the facility

3. Recovery of acid

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Advantages of acid recovery:

• Environmentally friendly

• No disposal or neutralization/clarification costs

• No acid loss. Therefore, the need for clean acid is reduced.

• Increased efficiency in production as it is a closed-loop system

• Improved cleaning speed and quality due to ideal and constant acid/iron concentrations in surface cleaning tanks

• Reuse of the water obtained in the HCl recovery system

• Obtaining commercially valuable by-products such as ferrous sulfate heptahydrate, iron(II) chloride