The object of the invention is a method as defined in the preamble of claim 1 and an apparatus as defined in the preamble of claim 8 for the handling of a granular material, such as fly ash, that is the input material, and also the use, as defined in claim 19, of the method and apparatus for sorting fly ash.

The method and apparatus according to the invention, referred to hereinafter more briefly as the solution according to the invention, is extremely well suited for handling and processing various materials classified as waste, such as e.g. the powdery or granular fly ash produced as a by-product of coal-fired power stations, into products fit for further refining. The fly ash produced as a by-product of coal-fired power stations is generally nowadays taken as waste to landfill sites, but it can be used when sorted into small grain sizes e.g. as an additive to cement in the manufacture of concrete, in the manufacture of asphalt, as an additive to grouting material, and also as an earthworks material. Fly ash is already used according to prior art for the aforementioned applications, but the results have not necessarily been sufficiently good, because the fly ash has generally been used as it is, without sorting in any way, in which case e.g. concrete, in which unsorted fly ash has been used as an additive, has been improved in terms of quality only to some extent or not at all. Cements supplemented with fly ash contain, in solutions according to prior art, generally approx . 15-35% fly ash. The use of untreated fly ash is typically seasonal, the amounts used are limited and, given the strict technical limit values set, the advantage to be gained has been small. Efforts have been made to refine fly ash also with solutions based on scrubbing technology, but these solutions are expensive and, in addition, a drying process for the fly ash must be added on.

One problem is also the construction of the handling apparatus for fly ash e.g. in connection with a power plant producing fly ash or in connection with some other plant using fly ash. The surrounds of the future apparatus must be dimensioned in the construction phase, in which case it is often necessary to travel to the construction site. In addition, a strange and - for the builder - new environment, as well as a local workforce, e.g. abroad, often causes extra difficulties for the builder. Likewise, the testing of the apparatus on site only after construction can be problematic.

The aim of the present invention is to eliminate the aforementioned drawbacks and to achieve an inexpensive and reliable method and apparatus for the handling of a granular material, such as fly ash. In this case the aim is to increase e.g. the reuse of fly ash in the concrete industry, in asphalt construction and in earthworks, and also at the same time to reduce the amount of fly ash and other industrial waste being taken to landfill sites. One aim is to achieve a solution whereby the fly-ash handling apparatus can be prefabricated at the factory and the operability of the apparatus can be pretested at the factory, and the tested and reliably operating apparatus can be delivered as a single assembly, or at least as a large subassembly, to its production site, where the apparatus is connected via its input connection e.g. to an ash silo that is the storage location of the fly ash that is the input material and via its output connection to a product silo, in which fly ash sorted by its grain size and composition is stored for coming on stream. Another aim is to achieve a remotely-controlled solution, which enables remote control of the sorting apparatus for fly ash and enables adjustments to be made to the apparatus by means of the remote control. The method according to the invention is characterized by what is disclosed in the characterization part of claim 1. Correspondingly, the apparatus according to the invention is characterized by what is disclosed in the characterization part of claim 8. In addition, characteristic of the invention is the use as defined in claim 19 of the method and the apparatus for sorting fly ash. Other embodiments of the invention are characterized by what is disclosed in the other claims.

One great advantage of the solution according to the invention is getting materials that would otherwise be classified as waste and handled as waste, such as e.g. fly ash, into reuse economically and extremely advantageously. In this case one advantage, among others, is a reduction in the C0 ₂ emissions produced in the concrete industry by the manufacture of cement, because less cement is needed for the manufacture of concrete when some of the cement is replaced with very well sorted fly ash. Correspondingly, ground limestone powder has conventionally been used as a filler in the manufacture of asphalt. Suitably sorted fly ash from the burning of coal is, however, well suited for the fine aggregate of asphalt surfacing, because it has homogeneous granularity, good capacity for filling porosity, a suitable low water content and it is alkaline. Since fly ash is in a bound form in asphalt mix, its environmental impacts are minor. Fly ash, and particularly fly ash sorted into a suitable grain size, can replace natural extractable soil resources e.g. in highway substrates. Fly ash is well suited to different filler structures, to foundations and to sound barriers in municipal engineering and special structures e.g. in harbors and landfill sites. One great advantage of the solution according to the invention is that the apparatus can be built to completion outside the final operating location at the factory of the apparatus manufacturer in favorable conditions and can also be tested at the factory before being taken into use. This enables reliability of operation of the apparatus at the production site and conformance to requirements of the end product manufactured with the apparatus. In addition, one advantage is that it is not necessary to travel in the construction phase of the apparatus so often to the production site and to foreign conditions, or even to a foreign country, which reduces costs and improves the quality of the apparatus. A further advantage is the remote control of the apparatus and of the production process, which also improves the quality of the end product and makes the production process more precise, enabling remote control of the apparatus and adjustments to be made by means of the remote control. Yet another advantage is that the apparatus could be disposed in a protected space, e.g. in a cargo container, which is easy to transport and which protects the structures of the apparatus and which is easy and quick to install in its production site.

One advantage is also that the solution according to the invention is extremely energy-efficient compared to solutions known in the art, because in the grinding device not all the raw material mass is ground, but instead only the material containing larger grains after the first classification. Another important advantage is that unground fly ash is mixed into ground fly ash. In this case there is fly ash containing the desired amount of unground, round fly ash particles in the finished end product, in which fly ash the fly ash particles are not broken in any way but instead are only sorted according to their grain size. This property according to the invention significantly improves the quality of e.g. cement in which an end product made with the method and apparatus according to the invention is used as one constituent. Another advantage also is that, owing to the modular construction, the structural solutions of the apparatus assembly are easy to change for achieving different end products. In this case by using only certain modules a product can be made in which e.g. a grinding device is not needed at all, or in the manufacture of which product it is also desired to use a different grinding device than originally anticipated. According to the invention, a granular material classified as waste, such as e.g. fly ash, that has been handled and sorted according to its grain size, can be called a micronized product, for which competing products are, inter alia, untreated fly ash according to prior art and silicon dioxide i.e. silica (Si0 ₂ ) . With the solution according to the invention e.g. the following advantages are obtained: The manufactured products are of homogeneous quality and technically reliable, products manufactured in this way replace more natural materials and replace more cement, the sorting precision and improved technical quality of the sorted product are better, the usage amount needed in the manufacture of concrete is smaller than with conventional fly ash, in which case raw material costs, transport costs and energy costs can be reduced, the ecological footprint is smaller than with conventional fly ash. One significant advantage is also that with the solution according to the invention, depending on the process adjustments, the desired amount of detrimental impurities can be removed from the input material to be sorted, e.g. 2-6% carbon can be removed from fly ash, the amount being removed significantly improving the quality of the fly ash to be used e.g. in cement and concrete.

In the following, the invention will be described in detail by the aid of one example of its embodiment with reference to the attached simplified drawings, wherein presents the method according to the invention as a simplified diagram,

presents the solution according to the invention as viewed from the side and as a simplified diagram,

presents a sectioned, diagrammatic and simplified side view of one sorting line, according to the invention, for fly ash in a protected space, such as in a cargo container, located at the production site,

presents a sectioned, diagrammatic and simplified side view of a second sorting line, according to the invention, for fly ash in a protected space, such as in a cargo container, located at the production site,

presents a diagrammatic and simplified side view of a product silo to be used in conjunction with the solution according to Fig. 4,

presents an oblique view from above of one solution according to the invention, wherein the apparatus assembly is composed of different prefabricated modules that are connected to each other at the production site for producing the desired end product,

presents a simplified view of the apparatus assembly according to Fig. 6, as viewed from the one side and with the nearest walls removed, and presents a simplified view of the apparatus assembly according to Fig. 6, as viewed from the other side and with the nearest walls removed.

In the solution according to the invention the granular material that is the input material, such as fly ash or similar material, is processed in such a way that it is no longer classified as waste. For the sake of simplicity, only a fly-ash handling process and apparatus is presented hereinafter although also meant at the same time are other similar granular materials that can, when sorted, be used for different purposes. In the method according to the invention fly ash is sorted and classified when dry for achieving the desired essentially precise grain size distribution. If necessary, the material that is already sorted, or a part thereof, is ground smaller and delivered again to the grain size sorting. In addition, for each grain size and material their correct applications are determined. The products sorted in this way, being different in their grain size, are kept each in their own reservoirs for future use. The grain size and composition of the end product being manufactured is preferably adjusted by remote control by means of the control system belonging to the solution by monitoring and adjusting the different functions of the apparatus.

Fig. 1 presents a simplified diagram of the method according to the invention. In it, the granular material that is the raw material, such as fly ash or other material suited for the purpose, e.g. material classified as waste, i.e. input material 7, is delivered from the storage location 2 for input material to a sorting process to be performed with the handling apparatus that is in the apparatus space 1 according to the invention, in which process the material is classified and sorted while dry according to the grain size of the material into different- sized fractions.

The apparatus space 1 is preferably a modular structure manufactured outside the production site, which can be composed of e.g. one module, such as a ship container, inside which the apparatus is built, or from a number of ship containers fitted to each other, in each of which is a certain suited-to-purpose part of the apparatus assembly. There can be 1, 2, 3, 4 or even more modules, and each of these can comprise different structures that are connected into one apparatus assembly at the production site by connecting the modules one beside another and/or one on top of another. The modules have connection parts that enable inter alia the passage of the material being handled from one module into another.

Preferably in one apparatus space 1 only one end product 9, i.e. a product type that is homogeneous in grain size and composition, is made with one handling apparatus. By using e.g. apparatus spaces 1 that are one beside another and in each of them an apparatus separately tailored and/or adjusted, end products that are different in their grain size and composition can be made for different purposes at the same production site from the same input material. Likewise, different end products 9 can, if necessary, also be made by changing the adjustment settings of an apparatus of one apparatus space 1, e.g. by means of remote control. The end products 9 sorted according to the invention are stored according to the respective material size and grain size in their storage locations 3, e.g. in silos functioning as storage reservoirs, from where the end products 9, e.g. fly ash screened and sorted into a certain different grain size, is delivered in the desired grain size and in the desired composition to end users, e.g. for the manufacture of e.g. cement, concrete and/or asphalt and/or for earthworks.

Fig. 2 presents a diagrammatic and simplified side view of one sorting line, according to the invention, for granular material, such as fly ash or corresponding waste material. At the production site, e.g. in connection with a coal- fired power station, cement factory or concrete factory, are e.g. one or more silos functioning as a storage location 2, in which is e.g. the fly ash, unsorted by grain size, that is the input material 7. In addition, at the production site are one or more silos functioning as a storage location 3 for the sorted end product 9, in which silo(s) is e.g. fly ash sorted by grain size, which is loaded for different intended uses e.g. into a transport vehicle 5 or into a cargo container by means of a loading bellows 4. The input material 7 is taken from its storage location 2 and transferred, e.g. by means of a conveyor 2a, to the handling apparatus according to the invention that is in the apparatus space 1, in which handling apparatus the input material 7 is dry sorted and conducted after sorting as fully sorted end product 9 to its storage location 3, e.g. by means of the suction brought about by a suction apparatus 6. Instead of a suction device 6, one or more blower apparatuses can also be used, which is/are disposed in the apparatus space 1.

One essential part of one embodiment of the invention is the apparatus space 1 that is presented in more detail in Fig. 3, for example, a large standard cargo container, a plurality of modular structures, such as cargo containers furnished at the manufacturer's factory with the device structures needed, the modular structures being placed one on top of another and/or one beside another and connected to each other, from which an apparatus assembly is composed, or some other corresponding protected space, inside which the sorting apparatus, i.e. handling apparatus, of the input material 7 is pre-installed at the factory of the apparatus manufacturer and in which also the operating values of the sorting apparatus are pre-adjusted and tested at the factory in such a way that the apparatus functions in the desired manner and produces the sorted end product 9 desired, which is stored in its own storage location 3 at the production site before transportation to the end user. In the apparatus space 1 is, inter alia, an input 7a for unsorted input material 7, a prescreen 10, a batcher 11, a first classifier 15, a grinding device 19, a second classifier 21, a product reservoir 26, a mixer 27 and a classifying fan 28, with which suction in at least a part of the conveying path of the input material 7 being sorted is brought about, with which suction the input material 7 being sorted is transported in the apparatus.

The input material 7, e.g. fly ash, to be sorted is guided along a feeder channel that is a part of the conveying path first via the input 7a for the input material 7 to a screening device functioning as a prescreen 10, in which the overlarge and indeterminate particles are separated from the fly ash and is conducted as the first fraction IF via the output 8 for material for removal as a material to be separately classified, e.g. as a material for use in earthworks. The apparatus comprises means for adjusting the prescreen 10 according to e.g. grain size, angle of slope and other desired criteria.

The granular material that has gone through the prescreen 10 drops as the second fraction 2F into a batcher 11, in the bottom part of which is an injector 12 connected to the suction duct 14, which injector is arranged to transfer the fly ash to be sorted along the suction duct 14 to a first classifier 15 via the input 16 of the classifier, which input 16 is in the bottom part of the classifier 15, in which case the incoming material flow travels upwards in the classifier 15. A sound diffuser 13, for damping the sounds produced by suction, is also connected to the injector 12.

The first classifier 15 is e.g. a device functioning by means of suction air, in which device the fly ash is divided into two different fractions according to its grain size, the smallest by grain size of which fractions, i.e. the third fraction 3F, which is unground and contains intact, essentially round fly ash grains, is conducted e.g. along the suction duct 17, into a product reservoir 26 that is inside the cargo container. Round grains, which are not broken in the grinder device 19, are essentially important in the end product because e.g. in cement they strengthen the strength of the cement. In addition, the separation of round grains from the material before grinding substantially reduces the energy needed for grinding.

Correspondingly, the fraction larger in grain size, i.e. the fourth fraction 4F, is conducted with a suitable conveyor arrangement 18 for size reduction to a grinding device 19, e.g. a jet mill, from which the ground material flow is conducted to a second classifier 21 by means of a conveyor arrangement 20, to inside from the bottom part of the classifier 21 and to flow upwards in the classifier 21. If necessary, additional air 15a is used as an aid to the functioning of the first classifier 15, by feeding said additional air in from the side of the classifier 15.

With the second classifier 21 the material is again divided into two fractions that are different in grain size, of which the fraction of smaller grain size, i.e. the fifth fraction 5F, is conducted onwards with the conveyor arrangement 23 to a conveying means 24 and via it to a mixer 27. Correspondingly, the fraction of larger grain size, i.e. the sixth fraction 6F, is conducted from the second classifier 21 with the conveyor arrangement 22 back to the batcher 11 and via it again into the sorting circulation of the apparatus. Alternatively, the fraction 6F that is larger in grain size can be conducted from the second classifier 21 with a suitable conveyor arrangement also directly back to the grinding device 19.

The input material 7 is e.g. >40 μτη in grain size, and in the prescreen 10 all indeterminate particles and particles having a grain size larger than 40 μπι, including most of the carbon particles to be removed, are taken out of it. In this case preferably e.g. 2-6% carbon is removed from the input material. The grain sizes referred to here are maximum grain sizes. After the prescreen 10 the grain size, i.e., particle size, of the material flow going to the batcher 11 and to the first classifier 15, i.e. the second fraction 2F, is smaller than 40 μπι. If a prescreen 10 is not used, the grain size can also be larger than 40 μπι. The smaller fraction leaving from the first classifier 15 along the suction duct 17 into the product reservoir 26, i.e. the third fraction 3F, is in this case e.g. <20 μπι in grain size and the material going on the conveyor arrangement 18 to the grinding device 19, i.e. the fourth fraction 4F, is e.g. <40 μπι .

The smaller fraction leaving from the second classifier 21 on the conveyor arrangement 23 to the conveying means 24, i.e. the fifth fraction 5F, is e.g. <20 μπι in grain size and the larger fraction leaving back to the batcher 11 or alternatively to the grinding device 19, i.e. the sixth fraction 6F, is e.g. >20 μπι in grain size. Finally, the material coming via the conveyors 24 and 25 to the mixer 27 is here e.g. smaller in grain size than 20 μπι, but there are some differences in the composition of both different fractions 3F and 5F . For example, the third fraction 3F is unground and contains a large amount of round, unbroken fly ash grains. For this reason the materials are further mixed in the mixer 27 to become an end product 9 that is as homogeneous as possible, which is transferred via the injector 12 into the storage location 3 for the end product 9. Presented above is only an example of one adjustment in size class according to the grain size of the material being sorted. The maximum grain sizes of the material to be sorted in the different phases of the sorting process can also just as well be selected to be other than this. Thus the final end product 9 sorted by grain size and by composition is made in the mixer 27, to which is taken the material sorted by grain size in the first classifier 15 from the product reservoir 26, e.g. via the aforementioned conveyor 25, and also at the same time the material sorted by grain size in the second classifier 21, e.g. via the aforementioned conveyor 24, and which sorted materials are mixed together by means of the mixer 27 and are also transferred via the injector 12 that is in connection with the mixer 27 by means of the suction apparatus 6 via the output 9a for the sorted end product 9 out of the apparatus space 1 and onwards to the storage location 3 of the sorted product 9.

With the classifier fan 28 suction is brought about for the conveying path of the input material 7 to be sorted, with which suction the input material 7 to be sorted is transported in the apparatus. The suction effect covers at least the batcher 11 and the first classifier 15 as well as the suction duct 14 between them and the suction duct 17 between the first classifier 15 and the product reservoir 26. The classifying fan 28 is in connection with the aforementioned devices and the aforementioned suction ducts via the suction duct 30 and product filter 30a. The blown air of the classifying fan 28 is conducted out of the apparatus space 1 via the air output 31.

In the apparatus space 1, in addition to the aforementioned parts, devices and functions, is also at least one suction connection/compressed air connection 32 as well as at least one electricity network connection 33, via which the apparatus space 1 and the devices therein can easily be connected to local compressed air and/or suction air and to a local electricity network. In addition, in the apparatus space 1 is a control system la, which also comprises a remote control arrangement. The remote control arrangement of the control system la is adapted to enable remotely controlled and remotely monitored apparatus functions, by means of which the devices and functions of the apparatus space 1 are made to function unmanned and in continuous operation .

In addition, the control system la and apparatus space 1 have adjustment means for adjusting the operating values of the apparatus in such a way that it is possible to adjust by remote control which product is made when. In this case e.g. one or more of the following is adjusted by remote control: the air volume, the travel speed of the material, the grinding power of the grinding device 19, the throughput speed of the grinding device 19, the amount of material going to the grinding device 19. The control system is adapted to be used also locally, in which case monitoring and all the necessary adjustments can be performed also in the apparatus space 1 or in the vicinity of it .

What is advantageous to the solution according to the invention is that the products made by sorting from granular waste material are stored in their reservoirs sorted into products according to the essentially precisely defined grain size desired, in which case the products are easy to use in the application for which they are exactly best suited, such as e.g. as an additive to cement for the manufacture of concrete.

Fig. 4 presents a second sorting line, according to the invention, for fly ash in a protected space 1, such as in one or more containers of modular structure, located at the production site. Many of the same device solutions as in the solution presented by Fig. 3 have been used in the solution according to Fig. 4. A difference now, however, that the unground third fraction 3F containing an abundance of unground, round fly ash particles and the ground fifth fraction 5F are not mixed into each other in the apparatus space 1, but instead only later, i.e. for example in conjunction with placement into the storage location 3. In this case from the apparatus space 1 two lines 9b and 9c are led out, of which line 9b contains the third fraction 3F, comprising an abundance of unground and round fly ash particles, and line 9c contains the fifth fraction 5F, comprising ground fly ash particles that are coarser in their granularity than the particles of fraction 3F . When the grain size of the third fraction 3F is <20 μπι, then the grain size of the fifth fraction 5F is e.g. <35 μπι. The solution according to Fig. 4 differs from the solution according to Fig. 3 in the progress of the process essentially only after the classifiers 15, 21. In this case a separate product reservoir 26 is not needed in the apparatus space 1 but instead the third fraction 3F is conducted through the filter 30a directly along the line 9b into the product storage 3. Correspondingly, the fifth fraction 5F is conducted through the filter 30b directly along its own line 9c into the product storage 3. The third fraction 3F and the fifth fraction 5F are mixed into each other outside the apparatus space 1 with air in a mixer 6a, which is disposed e.g. in connection with the product storage 3.

Figs. 6-8 present a type of solution according to the invention wherein the modular apparatus space 1 has been assembled e.g. from apparatus assemblies built into standard cargo containers. In this case the apparatus space 1 according to the embodiment is composed of four modules C1-C4, preferably of cargo containers according to standard, inside which containers the necessary apparatus assemblies have been prefabricated at the manufacturer' s factory. In the first module CI is e.g. an input 7a for the unsorted input material 7, a suction duct 14, which is arranged to convey the fly ash to be sorted, to the first classifier 15 situated in the second module C2 via the first throughput connection 14a, and the start end of the output line 9b of the unground third fraction 3F, the branch connector of which start end can be inside the module CI, as in Fig. 7, or outside module CI, as in Fig. 6. Correspondingly, in the second module C2, which is preferably disposed on top of the module CI, is a first classifier 15, by means of which the second fraction 2F is divided into the third fraction 3F and the fourth fraction 4F. In addition, in the second module are a suction duct 17a and the devices forming the suction or blowing pressure needed in the arrangement, such as a classifying fan 28 or corresponding devices, and a filter 30a through which the third fraction 3F is conducted via a second throughput connection 34 that is below the filter 30a to the start end of the output line 9b that is in the first module CI.

The throughput connections 14a and 34 are apertures, plus associated fastening means and sealings, that are prefabricated at the manufacturer' s factory at suitable points in the roof of the first module CI and in the floor of the second module C2. There can also be other corresponding throughput connections between the modules CI and C2. For conducting the input material 7 onwards, for example, if the input 7a for the input material 7 is arranged e.g. in the roof of the second module C2.

The third module C3 is disposed beside the first module CI and in the third module C3 is disposed e.g. an input for the coarser fraction separated in the first classifier 15, i.e. for the fourth fraction 4F, a grinding device 19, such as a ball mill, a conveyor arrangement 20 for transferring the ground fourth fraction 4F to the second classifier 21 via the throughput connection 21a, and the start end of the output line 9c of the ground and sorted fifth fraction 5F, the branch connector of which start end can be inside the module C3, as in Fig. 8, or outside module C3, as in Fig. 6. For the sake of clarity, neither the conveyor arrangement 18 with which the fourth fraction 4F is conducted to the grinding device 19 nor the conveyor arrangement 20 are presented in more detail in Fig. 8, but the conveyor arrangement 18 is e.g. brought from the module CI via the throughput connection 18a in the walls of the modules CI and C3 into the module C3.

Correspondingly, in the fourth module C4, which is preferably disposed on top of the third module C3, is a second classifier 21, by means of which the material is again divided into two fractions that are different in grain size, of which the fraction of smaller grain size, i.e. the fifth fraction 5F, the grain size of which is however larger than the grain size of the third fraction 3F, is conducted onwards with a conveyor arrangement 23a based on suction or blowing to a filter 30b, through which the fifth fraction 5F is conducted via a second throughput connection 34 that is below the filter 30b to the start end of the output line 9c that is in the third module C3. In addition, in the fourth module C4 are the devices forming the suction or blowing pressure needed in the arrangement, such as a classifying fan 28 or corresponding devices as well as an output line for conducting the sixth fraction 6F back to the grinding device 19.

The throughput connections 14a and 34 are apertures, plus associated fastening means and sealings, that are prefabricated at the manufacturer' s factory at suitable points in the roof of the first module CI and in the floor of the second module C2. There can also be other corresponding throughput connections between the modules CI and C2. For conducting the input material 7 onwards, for example, if the input 7a for the input material 7 is arranged e.g. in the roof of the second module C2.

In the method according to the invention the handling & sorting apparatus, i.e. the apparatus space 1, for granular material, such as fly ash, is assembled at the handling & sorting site, i.e. the production site of the desired end product, e.g. from the different modules C1-C4, which are furnished to be ready for production in the factory that manufactured the apparatus space 1, and which modules C1-C4 comprise different apparatus assemblies, and which are arranged to be connected at the production site of the end product by disposing the modules C1-C4 to be fitted together with each other either one beside another and/or one on top of another and by connecting the apparatus assemblies via the throughput connections that are on the roof, floor and walls of the modules, of which only the throughput connections 14a, 18, 21a, 34 are presented in Figs . 7 and 8.

Table 1 presents an extract from one test result, in which fly ash was sorted with a test device of the type of the method and of the apparatus according to the invention. In it, Product 1 is essentially unsorted coarse input material and Product 5 is the most fine-grained material of all. Four different percentage by volume values are presented in the vertical columns: D10, which corresponds to 10%; D50, which corresponds to 50%; D97, which corresponds to 97%; and D100, which corresponds to 100%. The decimal figures presented in the columns are the grain sizes of the material in micrometers (μπι) .

Volume % Volume % Volume % Volume %

Product 10 (D10) 50 (D50) 97 (D97) 100 (D100)

Product 1 1.82 μπι 16.44 μπι 99.16 μπι 225.00 μπι

Product 2 1.33 μπι 7.54 μπι 36.39 μπι 71.00 μπι

Product 3 0.90 μπι 2.86 μπι 13.94 μπι 60.00 μπι

Product 4 0.86 μπι 1.98 μπι 7.20 μπι 50.00 μπι

Product 5 0.84 μπι 1.46 μπι 2.85 μπι 4.00 μπι Table 1

For example, if looking at the lowermost Product 5, it is seen that in the sorting 100% of all the material has gone through the screen, the aperture size of which is 4 μπι, i.e. in the sorted product the largest grain size is 4 μπι. Generally, however, a more important criterion is considered to be a grain size with the value D97, which in most cases is sufficient instead of D100, and the product is usually evaluated with the value D50, with which the average fineness of the grain size of the product is determined. From Table 1 it is seen that the average fineness D50 of Product 5 is thus 1.46 μπι and more than 10% of the product is of material having a grain size of below 1 μπι, i.e. some of the product already belongs to the nanometer scale in terms of its grain size.

The handling and sorting of fly ash and other usable waste material into products of exactly a certain size in terms of their grain size enables the inexpensive and appropriate productive re-use of these products in different applications, in which the use of materials not sorted in this way could not earlier have been implemented. For example, fly ash selected according to exactly the correct grain size as an additive to cement used in concrete, among other things, improves the quality of the concrete and lowers the price of concrete and also reduces the consumption of cement. It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the example described above, but that they may be varied within the scope of the claims presented below. What is essential is that a granular additive product, such as fly ash or other material classified as waste, sorted by grain size according to the intended use, is used, in which case it is possible to know sufficiently precisely the grain size of the aforementioned additive product.

It is further obvious to the person skilled in the art that the process presented by the method according to the invention can also be implemented with other apparatuses than those presented above. Thus, for example, the screening device in the apparatus space is not necessarily needed in the apparatus and in the method, nor is a grinding device. In this case the grain size sorting is performed with only one classifier or with two or more classifiers, which are e.g. consecutive to each other.