Acid regeneration plants

In a conventional spray roasting process, the thermal chloride contained in the pickling acid is converted to metal oxide by thermal decomposition. The metal oxide composition then mirrors that of the pickled base material.

With the Wapur process introduced upstream of the spray roasting plant, much of the undesirable contamination can be removed from the pickling acid. Iron oxide, once a by-product, is thus turned into a valuable material which meets the stringent requirements of the electronics industry.

The Wapur process has many advantages

The untreated acid is pumped continuously from the waste acid storage tank to the leaching column in the Wapur system.

As the waste acid passes through the column, it is enriched with iron, using scrap from the trimming shears of the pickling line. In the leaching column, the residual free hydrochloric acid in the untreated pickling liquor is bound to the iron. The overflow from the leaching column flows into the reaction tank.

Here, ammonia solution is added to the waste pickling acid to increase its pH value. In this process step, part of the bivalent iron is transformed into iron hydroxide. This hydroxide then adsorbs the SiO2 particles.

The particles are precipitated in the sedimentation tank by means of an added flocculent. Piston membrane pumps convey the slurry from the sedimentation tank to a filter press. Together with the overflow from the sedimentation tank, the filtrate, i.e. the cleaned pickling acid, is routed to the storage tank.

Process advantages

• No waste water
• Can be added to an existing regeneration system
• No additional personnel required
• Adapts to variations in capacity
• Imports no changes to the existing regeneration plant’s operating procedures

Wapur process is very economical and produces high-quality material

• The iron oxide produced from the “waste” product creates an attractive source of revenue.
• The iron scrap used in the process is transformed into high-value iron oxide.
• Low utility consumption
• Continuous operation