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Economic preparation technology for ores, pellets, sinter mixtures and residual materials as well as for the production of graphite electrodes 24/06/2019

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EIRICH at METEC 2019: Economic preparation technology for ores, pellets, sinter mixtures and residual materials as well as for the production of graphite electrodes

The name EIRICH stands for the best possible mixing and processing quality, tailor-made solutions and high economic efficiency. Since 1960 the company has been supplying mixing and agglomeration plants for fine ores, e.g. for conditioning iron ore for subsequent pelleting. Around 1985 the preparation of sinter mixtures and the preparation of residual materials were added, in recent years the production of ore granulates for use in fluidized bed reactors. Mixers with a capacity of up to 12,000 litres operate highly efficiently in many plants worldwide. In 2018, an innovative testing device was developed for sinter preparation, which enables stabilization and increased performance of the sintering plant. EIRICH agitator bead mills with an installed motor power of up to 1100 kW are available for the efficient fine grinding of ores. For decades, EIRICH technology has proven itself worldwide for the preparation of graphite electrode masses; UHP quality electrodes in particular offer significant advantages.

At METEC 2019, technical solutions will be presented which enable small and large companies to work better and more economically.

The EIRICH mixing technology

The heart of a processing plant for ores, sinter mixtures and residual materials containing valuable substances is the mixing plant. The so-called EIRICH mixer – a further development of the ring trough and planetary mixer – shows its unique capacity here. The operating principle – a rotating pan for transporting the material to be mixed and a variable, slow to fast running mixing tool for mixing – brings advantages which are almost completely unique selling points. Compared to other mixing systems, friction and wear are greatly reduced. In many applications, this has led to the replacement of wear-prone single-shaft axial mixers / ploughshare mixers by EIRICH mixers.
With the EIRICH system, the speed of the mixing tool can be adapted to the respective task. The tool speeds can be between 1 and more than 30 m/s. The power input into the mixture can thus be specifically controlled. At high tool speeds, for example, dusts and sludges are blended into granules without any build-up on the mixing tool. At low speeds, granulates are gently mixed with other materials or coated. One and the same mixer can mix, granulate, coat, knead and disperse.

Conditioning of iron ore for pelletisation

Fine ores are mixed with binding agents. Because the mixer distributes better, the quantities of binders can be reduced. This results in considerable savings. In these plants, which operate with mixers with useful volumes of up to 12,000 litres and throughputs of up to 1500 t/h, running times of 9 months without wear repairs are standard.

Sinter preparation

In sinter preparation, customer reports indicate higher strength and permeability, a reduction in coke demand and an increase in the performance of the sintering plant. By granulating in the EIRICH mixer, up to 60% finest particles can be used without reducing the performance of the sinter belt. For stabilization and optimal, continuous control of the sintering process, a device has been developed which ensures fully automatic representative sampling and material analysis and thus a high and stable sintering quality. This instrument, first introduced in 2019 as QualiMaster MT1, leads to an increase in performance at the sintering belt.

Generation of ore granules for use in fluidized bed reactors

The power of a reactor is significantly influenced by the grain size and shape of the feed material. Granulates produced with the aid of EIRICH technology have proven to be the best feed material. The “raw materials” are often available as sludge or (filter) dust. EIRICH’s granulation technology makes it possible to convert these starting materials into a very uniform granulate within short batch times, e.g. 3 to 5 minutes, e.g. with a grain band of 0.5-1 mm. The grain band can be influenced to a large extent by varying the tool and speed; depending on the material, granulates with d50 of 100 µm to 5 mm are possible.

Preparation of recyclable residual materials

The EIRICH mixer also scores in the processing of residual materials. In recycling plants, it agglomerates steel mill dusts, sludges, mill scales, etc., e.g. for return to the sinter belt. For zinc recycling in the WAELZ process, residual materials (such as steel mill dusts, cupola furnace dusts, electroplating residues, zinc sludge, zinc ash and residues from the chemical industry) are mixed with a carbon carrier (such as coke), which serves as a reducing agent and energy carrier. Granules must be formed from the mixture. The use of EIRICH mixing technology has proven itself for mixing and granulating. Material of any consistency – from highly plastic to dusty – is mixed in high quality and processed into granulates. The better and more homogeneous distribution of the reducing agent enables a faster furnace throughput and thus an increase in production.

Preparation of ore-containing tailings

By means of a powerful mixing technology, flotation residues (tailings) which still contain a considerable amount of valuable material can be processed economically – even with varying moisture contents. For the recovery of recyclable materials, the residual materials usually have to be mixed and granulated with one or more other materials. The EIRICH technology makes it possible to process materials of all kinds and consistencies without any problems, e.g. to produce granulates from sludges with the addition of dry materials. Agglomerates are optimally broken down and the end product exhibits a very high mixing quality, even when auxiliary materials such as chemicals are added in the ppm range. In addition to batch mixers, continuous mixers are also used for these applications. One of the advantages is that there is no time for filling and emptying compared to batch operation. In addition, smaller mixers with lower drive powers can be used. In these cases, continuous mixing brings significant process and cost advantages.

Fine grinding of ores

Crushing is an integral part of ore processing. Fine grinding also exposes the finest ore particles from the surrounding mineral rock and prepares them for the subsequent wet separation process. EIRICH’s vertical agitator ball mills have been used for decades for the wet grinding of minerals containing ores, including iron, copper, zinc and gold ores. These mills, referred to as TowerMill, can ground mineral rocks to product finenesses down to P80 = 20 µm. In order to be able to process the high mass throughputs required in ore processing, various mill sizes are available with an installed motor power of up to 1100 kW.

Preparation of masses for graphite electrodes

In the production of the graphite electrode mass, coke is mixed with pitch and additives at temperatures of around 180 °C. This process determines the quality; in addition to optimum mixing of all recipe components, it is necessary to fill the pores of the coke with pitch as best as possible and to coat each individual coke particle with pitch. Sigma kneaders are not able to meet these requirements sufficiently well due to the system. If Sigma kneaders are replaced by EIRICH intensive mixers, a significant increase in quality is achieved.

The EIRICH mixing system with its power input that can be controlled via the shape and speed of the mixing tools enables both mixing and kneading. This results in fast homogenization. The cooling process from 180 °C mixing temperature to e.g. 120 °C processing temperature, which is carried out by adding water to the mixer (evaporation cooling), is also optimal; the melt temperature can be adjusted to +/- 2 °C.

Thanks to these advantages, processing in EIRICH mixers, called “EIRICH Mixer-Cooler” in the industry, has been established for about 50 years. Today, more than 25 batchwise plants with comparable EIRICH technology are in operation worldwide. A single EIRICH mixer can replace up to 12 kneaders. Productivity increases by up to 200 % with low investment and maintenance costs; the initial costs usually pay for themselves within a few years.

In addition to mixing, kneading and cooling, heating the coke to process temperature with EIRICH has now become easy for almost 40 years. Direct electric resistance heating brings the coke quickly and cleanly to the mixing temperature, without the fire hazard associated with simple heating systems and with less energy consumption. When small plant capacities are involved, it is worth combining heating and mixing; EIRICH offers mixers with induction heating for mixing temperatures up to 300 °C; this is of particular interest to manufacturers of graphite or carbon specialities.


EIRICH exhibits at METEC 2019 in Hall 4, Stand D27

EIRICH is looking forward to making your production more economical and cost-effective.


The EIRICH Group, with Maschinenfabrik Gustav Eirich as its strategic center in Hardheim, is a supplier of industrial mixing, granulating/pelletizing, drying and fine grinding machinery, systems and services. EIRICH has core expertise in processes and techniques used for the preparation of free-flowing materials, slurry and sludge. The main applications for these processes are in the ceramics, refractory, foundry, construction materials, plaster, rechargeable battery, battery compound, fertilizer, glass and ore dressing industries. Close co-operation between our own test centers around the world and collaboration with the research and academic community enables the “hidden champion” to provide solutions for innovative, cost-efficient products and processes. The family-managed company was founded in 1863 and operates from twelve locations on five continents.

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