Acid Microfiltration

The Steuler Acid Microfiltration (SAM) is mainly used for the filtration of mixed acid (HF/ HNO3),HF/H2SO4 and HCl, and has al🌳ready been well-proven in approximately 20 reference systems for 20 years.

Using this process the insoluble solids accumulated iꦇn the pickling solution are separated by continuous microfiltration and concentrated.

The objectives of the solid separation are:
— the 𝄹removal of the particles from the pickling bath - thꦅus the sedimentation of solids, the deposit and

    accumulation of mud in the pickling bath are re💃duced-consequently often plant shutdowns nec🅠essary

🦩&n❀bsp;   for cleaning the pickling baths are avoided and the consumption of acid is reduced
— the production of an absolutely solid-free filtrate that canꦚ be further used in a downstream process

    stage for cleaning the💛 free acid or♔ regenerating the total acid

Process description:
The complete homogenization of the particles𓆏 contained in the pickling bath is  a pre-condition for the separation of solids by means oꦗf filtra-

tion in a separate microfiltration cycle.Therefore we use different circulation cycles ♌and injectors in the strip and wire coil pickling line🦋s. Due to

a continuous mixing of the pickling baths the homogenized solids in the pickling solution are supplied to ✨the microfiltration system in a partial stream. One or more cross-flow-microfiltration modules are the principal parts of this separating stage where the pickling solution is pressed through the membrane at high speeds. The solids are completely retained at the surface of the membrane, strongly accumulated in the cycle

and drained with a small partial stream.  Because of the hyd💝raulic design and periodic backwashing the service life of the used acid-resistant microfiltration membranes is v♚ery long.

The plants are constructed in modular🧸 design and designed according to amount of the accumulated solids or to the filtrate flows that are re-

quired for the downstream acid purifi🎃cation/recovery.

Furthermore the design of the plants🃏 complies with the respective technical requirements/stan𝓡dards: At high pickling acid temperatures either

a single-stage heat exchanger ✨for cooling by cooling water or a double-stage heat exchanger can be installed. When using the latter, cooling

is carried o💯ut in the first heat exchanger stage with the filtrated pickling solution by heat recovery, so that only a small cooling water quantity 

is needed in the second stage.

The operation of the microf❀iltration system along with the periodical backwashing is fully automated. This includes the required rinsing of the filtration cycle in case of plant shutdowns, the main♔tenance or failures as well as rinsing of the acid feed and drain pipes.   This high process automation as well as the operation and documentation via the central processing unit (CPU)  are the main features ensuring a user-friendly design and operation of the plant.

When using an acid purification/ recovery downst🙈ream to the microfiltration systems, it is useful to concentrate the solids further in order to minimize the loss of free acid in the flow to be drained. This is achieved by thickening the pre-concentrated suspension in filtration by means

of sedimentation or hydro cyclone stages.

The main benefits in sum are:
— finest particles in the μm ᩚᩚᩚᩚᩚᩚ⁤⁤⁤⁤ᩚ⁤⁤⁤⁤ᩚ⁤⁤⁤⁤ᩚ𒀱ᩚᩚᩚrange are separated completely at high solid concentrations
— all used materials and diaphragms are a🦂cid-resistant
— the modular🍌 design makes it possible to retrofit the plant and increase the capacities subsequently
— high process automation and user-friend𒈔ly design in order to reduce the pe🐭rsonnel costs at the job-site the standardized plant parts can

    be pre-assembled