The steel process step by step

After melting, we add various dry products. Due to the heat, we cannot use added liquids because of the risk of vapour explosion. We use ceramic valves, hoses and pipes that can withstand the wear and tear.

The steel refining process

Transport and storage of acids

Centrifugal pumps are mainly used for the internal transport of the raw acid station. A magnetic drive pump can be recommended here as it is mainly a matter of safety as these are leak-free. From a raw acid station, the acids are usually pumped to a mixing tank. We can offer different types of tanks for this purpose. Dual laminate tanks, i.e. fibreglass tanks that are coated with a polymer that can withstand corrosion. These are also referred to as lined tanks. When using e.g. hydrogen fluoride, HF, it is preferable not to use fibreglass, so we recommend tanks in pure polymers, e.g. HDPE (high molecular weight polyethylene). For these mixing tanks, you can advantageously use a static mixer.

We sell PP and PVDF plastic valves for these applications. In cold outdoor environments we recommend fluoroplastic lined steel valves. These valves can withstand temperatures between -60 up to 200 degrees.In environments with acids the air is corrosive and needs to be ventilated away. This is advantageously done using grp pipes, grp fans and large dampers in various plastic materials.

prayer bath

Different acids are used depending on the type of steel to be pickled. When pickling carbon steel, sulphuric acid or hydrochloric acid is used. When it comes to stainless steel AISI 304 or acid-resistant steel AISI 316L, a mixed acid of, for example, 5% hydrofluoric acid, HF, and 20-25% nitric acid, HN03, is used. We can manufacture pickling tanks in lined glass fibre, GRP. The pickling tanks are heated with the help of heat exchangers, and we have both plastic and graphite heat exchangers to offer.

The pumps we recommend are shaft-sealed linear centrifugal pumps. Due to the metal particles, we cannot use magnetic drive pumps. In the environment around the pickling bath, we can offer gratings and supporting structures that can withstand the corrosion environment - these are made of glass fibre, GRP. In combination with the pickling bath, the choice of valves depends on the temperature. For the regeneration stage that comes when the pickling sludge is emptied, we mainly use linear centrifugal pumps.

Acid neutralisation department

The acid neutralisation section that comes after the regeneration, lime is used to neutralise the acid back to pH 7. If lime milk is used, we pump it with a centrifugal pump. On the other hand, if we use dry lime, we can use a hose for handling these in combination with a sending vessel. When we neutralise the milk of lime, we use a dynamic mixer in the lime mixing vessel. When we pump milk of lime, we need to use continuous flushing and then we use a so-called quench tank, otherwise the lime clogs the pump. The valves used in this step are usually hose valves, which at neutral pH can be made of natural rubber.

Filter press

The sludge produced after neutralisation is sent to a chamber filter press. To transport this sludge, we cannot use a normal centrifugal pump but use a filter press pump with 14-15 bar outlet pressure.

The internal treatment plant

This stage, which includes flocculation and sludge handling, requires both dosing pumps and, for example, hose pumps.