Here, ore mining began in the fourth century - a date which is supported by remains of melting furnaces found in the small Styrian town called Eisenerz (the German word for iron ore). The name could not be more characteristic. The reddish terraces of the Erzberg, the largest open cast mine of Central Europe and, at the same time, the largest siderite deposit worldwide, are widely visible.
It is estimated that since the beginning of the records, about 255 million tons of iron ore have been mined. The annual hewing amount is currently 9 million tons/year, 2.2 million of which are ore for sale. About 6,000 tons of ore are transported to the nearby smelting works in Linz and Donawitz every day.In order to further improve the quality of the extracted finished ore, sorting by means of a REDWAVE XRF-S was integrated in the corresponding processing line for the first time. The main purpose of the sorting plant is to sort out unproductive rock particles with an iron content of less than 20 % as well as ore grains containing interfering substances. The plant is operated according to demand, i.e. it only works when contaminated finished ore is going to be conveyed.
The chief editor of AT MINERAL PROCESSING met Dipl.-Ing. Armin Kogelbauer, Production Manager at VA Erzberg GmbH in Eisenerz/Austria, on site to learn more about the biggest iron ore mine in Central Europe and the new sorting system.
AT MINERAL PROCESSING: The name says it all – can you briefly describe Eisenerz as a mining location?
Kogelbauer: In 2012, we celebrated1300 years of ore mining. Ore mining has been carried out here for a long time. It really started during the reign of Archduke John who encouraged industrialization. Here at the Erzberg site, we have carbonatic iron ore with an iron content of 33.5 %. Compared to other deposits, as for example in Brazil, the content is relative, but due to the proximity to the steel works in Linz and Donawitz, we are a good supplier for smelting works. The smelting works appreciate our iron ore, because we are able to deliver very homogeneous material.
AT MINERAL PROCESSING: Who is behind the VA Erzberg GmbH and how big is the company?
Kogelbauer: The owner of the VA Erzberg GmbH is the VA Erzberg Private Foundation. Eisenerz with its altogether 220 employees, is the only site we have. It includes the subsidiary Maschinenservice Erzberg, which is active in special steel construction. The current processing plant was built in the early 1960s. It consists of a heavy-liquid enrichment plant with two drums, where the specifically lighter components such as lime and ankerite, are separated to reach the shipping quality of about 33.5 % iron.
AT MINERAL PROCESSING: How much longer will the iron ore last?
Kogelbauer: There are various scenarios: at the moment we go on the assumption of another 40 to 60 million tons of commercial products, i.e. we still have recoverable ore for the next 25 to 30 years. Furthermore, this long-term analysis will be carried out again if required, and then modified economic framework conditions will be included.
AT MINERAL PROCESSING: Meanwhile, many raw materials come from outside Europe – how do you see the future of the VA Erberg GmbH?
Kogelbauer: Our customers will still be able to use our iron ore over a long period – when this became clear we began to modernize the plants over the last three years. Not least in order to ensure the quality of our product and to improve indi-vidual quality parameters, respec- REDWAVE XRF - State-of-the-art technology for ore mining tively. Within this context we decided to incorporate sensorbased sorting.
AT MINERAL PROCESSING: Why did you decide in favor of a new sensor-based sorting plant?
Kogelbauer: The plant is used in the material flow that we call high-grade ore. There, we want to separate rock particles, which can be selected by classical sorting procedures to that extent. The aim is not primarily to separate low-iron grains from the flow, but also grains containing particular heavy metal contaminations. The sensor-based sorting machine REDWAVE XRF allows a more selective procedure regarding the iron and heavy metal content. Detection occurs in a grain size range between 30 and 120 mm – which was another reason for us to choose the sensorbased sorting.
AT MINERAL PROCESSING: With this you have broken new ground in iron ore dressing?
Kogelbauer: Originally, the manufacturers of sensor-based sorting plants contacted us and wanted to compete with the classical sorting methods in the coarse grain range, such as density separation etc. In the discussions, we were able to identify completely different applications for us. The REDAWAVE, which operates with X-ray fluorescence, enables the online determination of the iron content and the content of heavymetal contaminations as well as the clearing of grains so that they cannot reach the continuing product flow. Prior to this, the material flow passes the density separation.
AT MINERAL PROCESSING: What are the essential advantages of the new sorting plant?
Kogelbauer: On the one hand, an increase in quality of our end product and the better utilization of our resources, since the contaminated material can be sorted out very precisely. Grains with very low iron content will be removed and thus relieve the end product from undesired accompanying minerals. This in turn bears advantages for the operation of the sinter plant and for the pig iron production in the furnace. One of the most important topics when contemplating a possible sorting plant was, among others, the throughput. A pre-requisite for us is a minimum throughput of 100 t/h.