The present invention relates to a process and apparatus for producing elementary nanoparticulate mineral components (nanocrystallites) and rare metal oxides therefrom using primary and secondary mineral resources, such as ores, mineral-containing industrial wastes, e.g. from ore tailings ponds, residues, mud, slag, fly ash, EAF (Electric Arc Furnace) exhaust gas, emulsions, sludges from energetic, cohesive processes and their preparation operations.

Raw materials of modern industries, like electronics, lighting, energy production, pharmaceuticals and dyes, etc. consist of nanomaterials, i.e. nanosize particles of minerals, i.e. nanocrystallites, such as garnets, grossulars, metal silicates, hematites and goethite, zinc ferrite, perovskite, coal, coal derivatives, etc.

In a geological sense, both ores and coals are complex geological formations, mineral associations of known composition. During their hydrometallurgical and/or thermometallurgical processing, some minerals remain unchanged, together with their contaminating but valuable trace elements, while others are modified or new ones are formed. In the case of steel production, e.g. zincite is transferred without any change; zinc ferrite is newly formed, while in the red mud a bauxite residue of alumina production, hematite and goethite are present without change with their trace element scandium oxide, the newly formed cancrinite, hydrogrosular, with their trace elements, and perovskite. Bauxite, as a primary, i.e., mined mineral resource, is also a heterogeneous material that includes several aluminium hydroxide minerals (gibbsite, boehmite, and diaspore), iron oxide and iron hydroxide minerals (hematite, goethite), titanium mineral (anatase), quartz, and other silicates, and the association of their contaminating trace elements. The production of alumina from bauxite therefore generates residues in an amount more than one and a half times the amount of alumina produced, ie. red mud, being a secondary mineral resource with a moisture content of about 40% and a particle size of <40 microns after proper filtration and storage. Red mud and other processing wastes of ores, coal and lignite, debris, slag, flue ash, EAF exhaust gas, sludges, emulsions that is mineral ore clusters, contain valuable materials, metals, semimetals, rare metals, rare-earth metals, even precious metals as well in the form of crystalline MO _X , MS _X , MNx, etc. compounds or complexes thereof, for the extraction of which hydro- and thermometallurgical processes are developed.

US 2,203,9978, describes a system and process in which insoluble SiO2 silica is separated by muriatic dissolution of sloppy fly ash of coal, and then the strategically valuable materials are selectively trapped out from liquid reaction products by the use of a hydroxide reagent. Precipitates thus obtained include a mixture of iron, aluminium, magnesium, calcium, rare earths and transition metals. These can be separated as their hydroxides or converted into oxides and carbonates. If hydrochloric acid is used for dissolution and the chloride is converted to sodium chloride in the last step, then the process is almost waste- free. The silica can be further purified by leaching in NaOH or CaOH and some end products of the process can be recycled to minimize the amount of waste. The described system and process can be used to treat a number of other industrial wastes, such as red mud left over by the production of aluminium, slag from steel furnaces, mining dirt, and other metal-containing wastes.

A significant disadvantage of the solution is that its unit cost is relatively high, and environmentally severely harmful, toxic and corrosive chemicals, hydrochloric acid, caustic soda, slaked lime are used, which, even with the utmost care, poses a danger to the environment and workers.

It is therefore object of the present invention to provide a closed-loop physicochemical process and equipment for primary and secondary mineral resources, i.e. mineral associations, such as ores, industrial wastes, fly ash, mining wastes, blast furnace or steel slags, sludges and debris of other metallurgical processes like red mud and similar materials and ores stored today in huge amounts as hazardous wastes but containing valuable minerals, which process break them down into elementary, nanoscale mineral particles that make up these mineral associations, thus allowing all nanomaterials and rare metal oxides contained therein to be produced, without the use of toxic, corrosive and environmentally harmful chemicals.

This object was achieved by providing a process for producing elemental nanoparticulate mineral components and rare metal oxides therefrom using primary and secondary mineral resources as base materials, such as ores, mineral-containing industrial wastes, e.g. from mining wastes of ores, residues of energetic and metallurgical processes and from slag, fly ash, eaf exhaust gas, emulsions, sludges by filling the raw material into a mixing tank, wherein it is diluted with water to a 20% by weight colloidal solution, then the colloidal solution is fed to a colloid mill and dispersed into particles having an average particle size of up to 10 pm, then transferring it to a wet grinding attritor, the nanoparticulate colloidal solution thus obtained is passed under pressure to a classifying unit in which its nanocrystallite content is separated into at least two size fractions, each size fraction being dried in a vacuum drier, while a further nanocrystallite fraction containing trace elements is separated by the vacuum drier, which is passed to a separator where adsorbed rare metal trace elements are separated.

If the raw material is a lumpy, it is comminuted before filling into the mixing tank by coarse grinding and fine grinding in a tribo -electrostatic belt separator, wherein a nanocrystalline product containing at least one selected mineral is isolated.

The selected mineral is chosen from the group of minerals contained in ores, tailings or other industrial wastes.

A plurality of wet grinding attritors provided with decreasing sized steel balls are used in a cascade arrangement.

The maximum particle size of the particles previously reduced to less than 1 pm is further reduced to less than 800 nm, preferably less than 400 nm.

The colloidal solution is fed under pressure to a membrane-, cyclone-, or acoustic- separator or ultracentrifuge classifier having a cascade arrangement.

The nanocrystallite fraction containing trace elements is passed through a fluidized bed to the nano-tribo-electrostatic belt separator or a recirculation ion exchange unit via a cyclone separator.

Above aim was achieved also by providing an apparatus for carrying out a process for the production of nanocrystallites from ores or mineral containing industrial wastes according to the invention. The apparatus is formed by at least: a mixing tank, a colloid mill, at least one wet grinding attritor, a classifying unit, a vacuum dryer connected to a separator and a water collection tank, a nano tribo-electrostatic belt separator and a recirculation ion exchange unit successively connected in this order.

A coarse crusher and a fine crusher and a tribo-electrostatic separator are arranged downstream of the mixing tank, whereby the lumpy material which can be processed by the method and apparatus according to the invention is crushed up to the order of millimeters, or even smaller particles are slurried, suspensions and slurries are dispersed with water to produce a colloidal solution containing 20 m% of dry material with max.10 pm particle size, then grind it further in an ball mill up to a nano-sized state. This is followed by the separation of nanocrystallites by species in a clean room with a nano membrane or acoustic separator, or using an ultracentrifuge or cyclone. After individual vacuum drying of different nanocrystallites thus obtained, the water is returned to the disperser, and the nanocrystallite free of impurities (trace elements) is packaged in a closed metal barrel. Rare metal oxide trace elements are separated from the impure nanocrystallites by a tribo electrostatic separator or in a recirculation ion exchange unit and fed to separate sealable metal boxes.

The invention will now be described in more details with reference to the accompanying drawings. In the drawing

Figure 1 shows a flow chart of the process according to the invention.

Figure 1 shows a flow chart of the process according to the invention. The first embodiment of the process according to the invention is described by the processing of bauxite and bauxite residue (red mud), however, instead of bauxite, other ore, mining waste or processing waste can be processed. The bauxite is a lumpy raw material 1 which is fed to coarse crushers 2, where its average particle size is reduced to less than 10 mm. Since the bauxite has a particle size suitable for further processing according to the invention is of the order of mm, the coarse-grained bauxite is fed into a fine cone crusher 3, where its maximum particle size is reduced to less than 1 mm. In this size range, according to their zeta potential-based charge, the aluminium minerals can be separated from other minerals and their contaminating trace elements on respective positive and negative comers of a belt tribo-electrostatic separator 4, and then appearing as an aluminium mineral product that can be processed into metal aluminium by way of electrolysis. The other minerals thus separated, together with their trace elements, are filled as secondary raw materials 6 into a mixing tank 7, where they are diluted with water to a 20% solution. From the mixing tank 7 the 20% by weight colloidal solution is fed into a colloid mill 8 and dispersed into particles with an average size of max. 10 microns. It is then passed through energetic wet grinding attritor 9, preferably a plurality of mills 9 in a cascade arrangement each provided with decreasing sized steel balls, until the expected maximum crystallite particle size of a few hundred nanometers, preferably 800, more preferably 400 nanometers is reached, but in each case remains in nano range that is below 1 pm.

The resulting nanoparticulate colloidal solution is fed under pressure, preferably to a plurality of membrane, acoustic, or ultra centrifugal classifiers 10, where a separation starting from the smallest nanoparticles and passing through units 10 with increasing membrane porosity or centrifugal filter porosity up to the separation of further nanoparticles. Each nanoparticulate crystallite fraction is passed through a vacuum dryer 11 to a container 12 or directly to a packaging machine (not shown).

A portion of the trace element-containing crystallites deposited on the vacuum dryer 11 is passed together with adsorbed trace elements, through a fluidized bed (not shown, but known per se), to a nano tribo-electrostatic belt separator 13, e.g. the dielectric scandium oxide adsorbed on the electrically conductive hematite and goethite crystallite are separated and packaged by a packaging machine at the poles in sealable containers 14. The electrostatically unresponsive trace elements are separated in a recirculation ion exchange unit 13a and then packaged in sealable containers 14 as well.

Crystallites of the same nanosize can be separated e.g. in a cyclone system separator I la based on their specific density, then separately transferred to a vacuum dryer 11 , then to a fluidized bed, then to a nano tribo-electrostatic belt separator 13 or a recirculation ion exchange unit 13a, and finally to be packed. Thus, crystallites of the same nanosize, e.g. both the cancrinite and the hydrogrosular crystallite, having a particle size of 99 nanometers and a density of 3.594 g / cm3 and 4.03 g / cm3, are separated on the basis of their specific gravity, for example in a cyclone separator I la, and then transferred separately to a vacuum dryer 11, then to the nano tribo-electrostatic separator 13 and a container 12, or to the recirculation ion exchange unit 13a, and to a sealable container 14. The water condensed in the vacuum dryer 11 and the cyclone separator 1 la is returned to the mixing tank 7.

The process according to the invention is of course suitable not only to process raw materials 1 in a lumpy state, but also for other wastes, e.g. it is also suitable for processing raw material 15 is a slurry state, EAF exhaust gas raw material 16 and emulsion as raw material 17. During e.g. the production of alumina, a bauxite residue i.e. red mud is generated as waste in an amount of more than one and a half times the amount of alumina produced, which can be considered as a secondary mineral resource due to its valuable mineral content. The red mud has a moisture content of about 40% after filtration and storage, with a particle size <40 microns.

During the processing of a sludge 15 as a raw material, e.g. red mud, the red mud extracted from the reservoir is filled directly into the mixing tank 7, where it is diluted to a 20 m% solution with water, then feeding to the colloid mill 8 and dispersed into particles of up to 10 microns, after which it is transferred to the grinding ball mill 9.

During processing of an emulsion 17 as base material or powder 16 e.g. blast furnace fly ash, the fly ash from the separator of the iron or steel mill is also filled directly into the mixing tank 7, where it is similarly diluted to a 20 m% solution with water, and feeding into the colloid mill 8 and dispersed into particles of up to 10 microns and then transferred to the grinding ball mill 9.

It can be seen that the processing of the primary and/or secondary mineral resources downstream the mixing tank 7 takes place in the same way.

Apparatus for carrying out the process according to the invention shown in Figure 1 contains at least a mixing tank 7, a colloid mill 8, at least one wet grinding attritor 9, a classifying unit 10, vacuum dryer 11, and nano- triboelectrostatic belt separator 13 all arranged and connected to each other in series according to the process, and preferably also contains a tank 1, a coarse crusher 2, a fine crusher 3, and a further tribo-electrostatic separator 4.

In summary, the process of the present invention is for producing elemental nanoparticulate mineral components and rare metal oxides therefrom using primary and secondary mineral resources as base materials, such as ores, mineral-containing industrial wastes, e.g. from mining wastes of ores, residues of energetic and metallurgical processes and from slag, fly ash, EAF exhaust gas, emulsions, sludges. During this process the raw material 1,15,16,17 are filled into a mixing tank 7, wherein it is diluted with water to a 20% by weight colloidal solution, then the colloidal solution is fed to a colloid mill 8 and dispersed into particles having an average particle size of up to 10 pm, then transferring it to a wet grinding attritor 9, the nanoparticulate colloidal solution thus obtained is passed under pressure to a classifying unit 10 in which its nanocrystallite content is separated into at least two size fractions, each size fraction being dried in a vacuum drier 11 , while a further nanocrystallite fraction containing trace elements is separated by the vacuum drier 11 , which is passed to a separator 13,11a where adsorbed rare metal trace elements are separated. In a specific embodiment of the process according to the invention the raw material 1 is lumpy, that is comminuted before filling into the mixing tank 7 by coarse grinding 2 and fine grinding 3 in a belted tribo -electrostatic separator 4, wherein a nanocrystalline product 5 containing at least one selected mineral is isolated. This selected mineral is chosen from the group of minerals contained in ores, tailings or other industrial wastes. A plurality of wet grinding attritors 9 with decreasing sized steel balls is used in a cascade arrangement in order to further reduce the 1 pm maximum particle size of the particles to less than 800 nm, preferably less than 400 nm. Te colloidal solution is fed under pressure to a membrane-, cyclone-, or acoustic-separator I la or ultracentrifuge classifier 10 in a cascade arrangement, and nanocrystallite fraction containing trace elements is passed through a fluidized bed to the nano-tribo-electrostatic belt separator 13 or a recirculation ion exchange unit 13a via a cyclone separator I la.

The apparatus for carrying out a process for the production of nanocrystallites from ores or mineral containing industrial wastes is formed from at least: a mixing tank 7, a colloid mill 8, at least one wet grinding attritor 9, a classifying unit 10, a vacuum dryer 11 connected to a separator I la and a water collection tank 11b, a nano tribo-electrostatic belt separator 13 and a recirculation ion exchange unit 13a successively connected in this order. Preferably a coarse crusher 2 and a fine crusher 3 and a further triboelectrostatic separator 4 are arranged upstream of the mixing tank 7.

The advantage of the process and apparatus according to the invention for processing industrial wastes, i.e. mineral associations, such as ores, industrial wastes, fly ash, mining wastes, blast furnace or steel slags, sludges and debris of other metallurgical processes like red mud and similar materials and ores stored today in huge amounts as hazardous wastes but containing valuable minerals, is that avoiding thermometallurgical or hydrometallurgical destruction of valuable mineral clusters to extract less valuable metal compounds, and also omitting the use of chemicals that are toxic and corrosive, and severely harmful to the environment.