Customized Engineering

RAUCH will also gladly take over the planning of a foundry for you. Every need can be satisfied with the wide range of products and the modular products.

The RAUCH Top Blown Rotary Converter is used for recycling steel scrap. 

An example: The mineability of zinc ore is currently around 4% zinc content. Flue dust from the steel industry contains up to 40%. The sustainable and energy-efficient recovery of this dust is of the utmost importance today, however it places high demands on process management and the required systems. 

The development of pyrometallurgical processes for extracting such materials from steel industry residues also requires corresponding experiments with appropriate facilities in pilot-scale. RAUCH has taken up this challenge with the construction of a Top Blown Rotary Converter. 

Design:

• Rotating and tiltable reaction vessel to heat residues to above 1300°C by means of oxygen burners and to separate and recover the material contained therein (zinc, lead, copper, ...).

This system is used by the Institute of Non-ferrous Metallurgy at the University of Leoben and the adjoining Christian-Doppler Laboratory as a testing facility for evaluating the metallurgical processes when recycling complex residues.

The aim of this Customized Engineering project was to make a steel surface corrosion-resistant by steaming with Magnesium and Zinc. 

It is known that magnesium is becoming increasingly important in the steel industry, but it serves as an important desulphurising agent in steel production. However, it is ostensibly less well known that pure magnesium also provides excellent corrosion protection if it is used to cover steel surfaces – similarly to galvanisation. An extremely thin Magnesium – Zinc layer forms a compact protective film, which protects the steel surface against corrosion.

The following problem was to be solved:

• Continuous provision of clean Mg melt.
• Continuous transfer of this melt from the furnace to a vaporiser under high vacuum.
• Controlled transfer of the magnesium vapour from the vaporiser through steam pipes with control and shut-off valves to a continuously passing steel strip, in order to re-sublimate the steam on both sides in a dense layer of a few micrometres thickness, also under high vacuum.

This was implemented in two steps:

1. The creation of a test facility on a laboratory scale. In this respect, experience could be gained with regard to the materials to be used, particularly for valves for the magnesium vapour and seals, as these must retain their functionality at temperatures of 700°C and high vacuum.
2. Creation of a pilot system on an industrial scale. The considerable lengths of the melting and steam pipes became additional challenges. The mechanical loads of the containers, pipes and fittings due to evacuation and tempering required extensive calculations and targeted measures (compensators, floating bearings, pre-loading, etc.), so not to overload the materials exposed to over 700°C in case of an internal vacuum.

The system was put into operation on time and handed over on a turnkey basis to the full satisfaction of the client.

One often incorrectly associates lightweight construction in the automotive sector with the industrial application of magnesium and its alloys. However, there are also promising Mg applications in many other areas.

An example of such an application is the efficient storage of hydrogen in the form of metal hydride and in two respects:

• On the one hand, certain magnesium alloys in the form of fine powder are the medium for hydrogen storage, and on the other hand, such storage units require a temperature of around 340°C in order to store and dispense hydrogen with the required dynamic and under suitable pressures. In order to optimally maintain this temperature, the actual storage medium is embedded in a latent storage unit: This latent storage unit also consists of a Mg alloy. It enables the storage of the thermal energy produced during the loading of the storage unit and to provide it during the extracting of hydrogen. The energy density level during the phase transformation of the latent storage unit enables a very compact construction.

RAUCH was entrusted with the task of establishing a melting and dosing unit for such a latent storage unit alloy. When developing this melting and dosing unit, RAUCH was able to use the many years of experience in the development and production of magnesium and zinc furnaces.

Challenge:

• The challenge was to fill the melt into the cavity with the metal hydride storage unit saturated with hydrogen, so that it does not overheat and the pressure of the hydrogen in the storage unit remains within a predetermined range.

Design:

• The temperature of the melt can be precisely maintained down to a few tenths of a degree in the furnace by means of various heated zones and a special agitator design.
• When filling the latent storage unit with a precisely controllable centrifugal pump, the melt flow of the eutectic alloy can be controlled depending on the pressure of the hydrogen in the hydrogen storage unit.
• Filling is complete as soon as the container reaches the required weight; an additional contact sensor is used as a redundant switch-off device, so that fully automatic filling is ensured.

In order to achieve very good, constant quality of the manufactured product, it is necessary to control the process from start to finish. In order to ensure complete control, a higher-level visualisation system is required, which records the process data and logs when limit data is exceeded. 

Advantages of the RAUCH visualisation system:

• A central system that is brought together in a control room, which collects and stores all data.
• Possibility of monitoring the operating conditions at central control rooms.
• Creation of batch reports, operation and malfunction analyses, reports on waste products, etc.
• The existing processes are analysed and optimised in the course of visualisation implemented by RAUCH.
• Furthermore, external devices, such as the spectrometer, can also be integrated in the process recording.