Hydrometallurgy/Urban Mining

As part of the growing electric mobility the topic of “mobile power supply” is of central importance. The current state-of-the-art technology for compact and mobile power supply units in electric vehicles is the Lithium-Ion battery. In addition to this battery technology there are numerous other concepts based on nickel-cadmium or metal hydride technologies. The Lithium battery is considered the most promising version for the future. For this reason the demand for Lithium will continue to rise, in conjunction with the increasing number of electric vehicles, and other devices, coming on the market. The Lithium-Ion technology, however, is considered expensive. According to the current level of development of electric mobility the battery is the most expensive part of the electric car. This is also linked to the raw material supply of the market. An essential approach to the lowering of battery prices is, from MME’s point of view, that technologies be made available which can recover the raw material Lithium as a pure substance from dead Lithium-Ion batteries, in order to feed it into a closed circuit of the manufacturing industry. Because Lithium-Ion batteries are made of a number of different materials the challenge is to design suitable technological concepts for separating the individual metal fractions. MME is rising to the challenge of establishing suitable recycling concepts.

Based on the academic work and multi-years of research by our company’s founder in the field of tungsten and cobalt chemistry, MME Engineering has a deep understanding of this metallurgical discipline. Also in the field of refractory metallurgy, the topic of recycling is getting more important. MME Engineering has the know-how for processing secondary raw materials containing tungsten based on hydrometallurgical process operations for extracting the pure metals tungsten, cobalt, nickel, iron, titanium etc.

The chemistry of cobalt is strictly linked to the recycling of cemented carbide scraps. This strategic important raw material is needed for the production of hardmetal alloys as binder phase. Additionally cobalt is applied as alloying component in High-speed steels and superalloys like INCONEL. Further examples for the field of applications are catalysts, which are used for desulphurization in the petrochemical section, so called Hydrofiner.

Cobalt is a quite seldom element. It comprises only about 0.004% of the earth´s crust. The well-known cobalt deposits are located in political unstable regions, for example in the Republic Kongo. This country is the biggest producer of cobalt bearing ores. Because of it´s outstanding role in the high technology sector it is very important for the western world to have technologies for keeping the raw material circuit closed.

The overarching term “Urban Mining” is used in the professional world and stands for increasing readiness also in the field of assuring a supply of raw materials to describe concepts for developing ways to extract valuable materials from existing waste storage facilities in order to feed these back into the production industry. MME Engineering’s approach to this topic lies in hydrometallurgical concepts. Old repositories which in some cases store several different metals, are transitioned to the hydrous phase by means of chemical decomposition. By means of steps of separation, one can extract elemental metals.

Control Technologies for iron in hydrometallurgy

Iron is present as an associated material in nearly all initial materials. The topic of iron control is the object of continuous professional discussion, which shows how important this topic is for refining in hydrometallurgy. The hydrolytic precipitation of haematite from salt acids or sulphuric acid solutions is a technological possibility for selective separation of the iron fraction from hydrous leachates. This process is known in the literature under the name “PORI-process” and can be used in combination with many other hydrometallurgical process steps for shaping new hydrometallurgical processes.

Red sludge processing from the aluminium industry

Red sludge is a ferrous by-product from extraction of aluminium from its ores. The classical process is called the Bayer-process. The characteristic colour from its ores comes from iron (III)-compounds. Mostly these are Fe(OH)3 or Fe2O3. Along with iron, depending on the origin of the ore, there are considerable amounts of TiO2presenting red sludges. They can also contain traces of poisonous heavy metals such as mercury, cadmium, chromium, arsenic. The red sludges are deposited and mostly not fed into additional processing. This depositing becomes an environmental problem when poisonous substances from a deposit get into the ground water or dams break and contaminate entire swathes of land, such as happened in Hungary in 2010.

MME Engineering is in the position to make a technological contribution to the processing of red sludges and extracting iron.

Copper was one of the first metals that brought humankind forward in its technological development. It is certainly a metal that is still of great significance in technology today. It is difficult to replace with other metals particularly in the electro-technical field. Virtually all electrical and electro-technical components are manufactured out of a variety of different metals. A homogenous separation of copper requires corresponding knowledge of the hydrometallurgical chemical composition. MME knows the corresponding technological strategies for recovery of copper from secondary raw materials, such as slag and scrap metal. In the discipline of hydrometallurgy there are many technological concepts possible in order to achieve the desired Goal.

Practically the only process for extracting aluminium used today is the so-called Bayer-process. In this process bauxiteis disintegrated under pressure using sodium hydroxide solution at 180°C. Here the aluminium selectively precipitates as Na[Al(OH)4], while the iron is separated as oxide-hydrate (red sludge) by means of filtration. Due to the fine distribution of the precipitant, the filtration is often plagued by considerable technical problems. The aluminium fraction is brought to crystallisation and then converted into aluminium oxide at around 1200°C . The silicon dioxide from the bauxite converts into sodium-aluminium silicate in wet extraction, which precipitates together with red sludge. The formation of these silicates is then associated with losses of aluminium, which naturally increase with higher concentrations of SiO2 in the bauxite.For this reason there is limited applicability for the classical Bayer-process, which has been constantly optimised over the decades, stemming from the composition of the initial materials.

MME Engineering has know-how concerning alternative routes for extracting aluminium out from primary or secondary raw materials with high proportions of silicate and/or high iron concentrations. With these procedures it is possible specifically to process raw materials with low concentrations of aluminium. Simultaneous separation of iron and aluminium is the key point in this procedure.