METHOD AND APPARATUS FOR REGENERATING INDUSTRIAL SAND

Abstract

In the method, adding (110) an aluminium silicate based additive to industrial sand, heating (120) the industrial sand and the additive added to it, whereby the additive reacts with impurities, that comprise at least alkali metal, in the in dustrial sand thus forming at least partially melted alkali salts, bringing (130) the heated industrial sand and the alkali salts into a motion occurring in relation to each other, whereby at least part of impurities remaining in the industrial sand adhere to the alkali salts thus forming grains, and sepa rating (140) industrial sand for removing grains from indus trial sand. An apparatus for regenerating industrial sand, which apparatus comprises a feeder (220) for feeding indus trial sand and an additive to a processing apparatus (300), a processing apparatus (300) for heating the industrial sand and the additive added to it, and further bringing the indus trial sand and the additive added to it into a motion occurring in relation to each other, and a separation device (400) con figured to separate industrial sand for removing grains from industrial sand.

Description

1 / 20 “METHOD AND APPARATUS FOR REGENERATING INDUSTRIAL SAND” BACKGROUND OF THE INVENTION

[001] The invention relates to the regeneration of industrial sand using an additive. Specifically, the invention relates to the thermomechanical regeneration of industrial sand using an additive.

[002] Typically, industrial sand is defined by several requirements depending on its use related to its strength, loss on ignition, acid demand value, pH value and / or grain shape. These requirements are not necessarily met by used industrial sand because used industrial sand comprises binders and impurities adhered to the sand, thus preventing the fulfillment of at least some of the aforementioned requirements.

[003] According to one practice, industrial sand can be thermally regenerated in a fluidized bed reactor or, according to another practice, industrial sand can be thermomechanically regenerated in a rotary kiln, i.e., a combustion furnace. However, thermally or thermomechanically regenerated industrial sand does not meet the defined requirements for its use because regenerated industrial sand comprises adhesives and impurities adhered to it and thus prevents the fulfillment of some of said requirements. BRIEF DESCRIPTION OF THE INVENTION

[004] The object of the invention is to provide a new type of apparatus and method for regenerating industrial sand.

[005] The method according to the invention is characterized by, in the method, adding an additive based on aluminum silicate to industrial sand. Additionally, in the method, heating the industrial sand and the additive added to it, whereby the additive reacts with impurities containing at least an alkali metal in the industrial sand, thus forming at least partially molten alkaline salts. Additionally, in the method, placing the heated industrial sand and alkaline salts in a motion that occurs relative to each other, whereby at least some of the impurities remaining in the industrial sand adhere to the alkaline salts, forming, Petition 870250080613, dated 08 / 09 / 2025, pp. 66 / 94 2 / 20 thus, grains. In the method, further separate the industrial sand to remove the grains from the industrial sand.

[006] An apparatus according to the invention is characterized in that the apparatus comprises a feeder for feeding industrial sand and an additive to a processing apparatus. Additionally, the apparatus comprises a processing apparatus for heating the industrial sand and the additive added to it and, furthermore, for setting the industrial sand and the additive added to it in motion relative to each other. The apparatus further comprises a separation device for separating the industrial sand by removing grains from it.

[007] One advantage of the method and apparatus according to the invention is that the physical-chemical processing performed in the processing apparatus substantially removes binders and impurities from the industrial sand.

[008] Some embodiments of the invention are presented in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[009] The invention will now be described in more detail with regard to preferred embodiments and with reference to the accompanying drawings, in which: Figure 1 schematically shows a method for regenerating industrial sand, Figure 2 schematically shows another method for regenerating industrial sand, Figure 3 very schematically shows an apparatus for implementing the method of Figures 1 and 2, and Figure 4 very schematically shows another apparatus for implementing the method of Figure 1. DETAILED DESCRIPTION OF THE INVENTION

[010] Industrial sand refers to regenerable sand that has been used in industry, such as in the foundry industry. Industrial sand can be, for example, resin sand. Petition 870250080613, dated 08 / 09 / 2025, pp. 67 / 94 3 / 20 phenolic sand comprising organic resin as a binder and an additive added to the binder, wherein the additive added to the binder may be, for example, an ester hardener. Industrial sand may be green sand comprising at least bentonite as a binder and an additive added to the binder, wherein the additive added to the binder may be, for example, carbon. Industrial sand may be furan resin sand. Industrial sand comprises impurities containing alkali metal, such as, for example, potassium and / or sodium. Impurities in industrial sand may be in the binder of the industrial sand and on the surface of a grain of sand of the industrial sand. There may be requirements relating to industrial sand for end use regarding sand firmness, loss of ignition (LOI), acid demand value (ADV), sand grain shape and / or cracks that may occur in sand grains.It should be mentioned that industrial sand can refer to regenerable sand that has been used, for example, in the energy industry. As a binder, power plant sand may comprise, for example, a clay-based impurity film.

[011] For example, when industrial sand is regenerated thermomechanically, the industrial sand is heated and set in motion mechanically by means of a furnace, in which binders in the industrial sand are released, at least partially, as a result of heat and collisions, but in which impurities on the surface of the sand or sand grain are not sufficiently released. When thermally or thermomechanically regenerated industrial sand is reused, said impurities can hinder the use of regenerated sand, for example, in that the impurities prevent the binder to be added to the sand from working, in which the binder affects the requirements related to industrial sand.For example, impurities comprising alkali metal compounds, such as potassium residues, can remain in green sand that has been thermally or thermomechanically regenerated, and these prevent a binder, such as bentonite, from working in the green sand in the foundry industry, so the target firmness defined for the area is not achieved. Prevention of binder... Petition 870250080613, dated 08 / 09 / 2025, pp. 68 / 94 Working with 4 / 20 can lead to larger quantities of binders being used in industrial sand to meet the defined requirements for the sand.

[012] Figure 1 shows a method for regenerating industrial sand. Figure 2 shows another method for regenerating industrial sand. Figure 3 shows an apparatus comprising a processing apparatus 300 based on a thermomechanical operating principle, wherein the processing apparatus 300 is a rotary kiln 300A, i.e., a combustion furnace 300A. Figure 4 shows an apparatus comprising a processing apparatus 300 based on a thermal operating principle, wherein the processing apparatus 300 is a fluidized bed reactor 300B.

[013] The apparatus of the figures comprises a feeder 220, a processing apparatus 300 and a separation device 400. The feeder 220 is configured to feed the processing apparatus 300 with industrial sand and an additive, or more specifically, the feeder is configured to feed the processing apparatus 300 with industrial sand and the additive added to it, wherein the additive will be described in more detail below. The processing apparatus 300 is configured to heat the industrial sand and the additive added to it, whereby the additive reacts with impurities, containing at least an alkali metal, in the industrial sand, thus forming at least partially molten alkaline salts.Additionally, processing apparatus 300 is configured to place the industrial sand and heated alkaline salts in a motion relative to each other, whereby at least some of the impurities remaining in the industrial sand adhere to the alkaline salts, thus forming grains. In more detail, said alkaline salts thus form grains or agglomerates of grains. Separation device 400 is configured to separate industrial sand to remove grains from it. Separation device 400 is configured to separate industrial sand to remove grains and agglomerates from it.

[014] The removal of impurities occurs as a result of a physical event. Petition 870250080613, dated 08 / 09 / 2025, pp. 69 / 94 5 / 20 chemical. Industrial sand is heated and set in motion, whereby binders in the industrial sand are burned and released, in which, for example, carbon in the industrial sand burns due to the effect of heat. The industrial sand and the additive added to it are heated, for example, to 500-850 °C, 600-800 °C, 650-750 °C or 700-750 °C. The additive reacts with the impurities in the industrial sand and released from the industrial sand, thus forming at least partially molten alkaline salts. In more detail, the additive reacts with impurities in the binders of the heated industrial sand, thus forming at least partially molten alkaline salts, which said impurities are at this stage in their molten state during reaction with the additive.For example, an additive based on aluminum silicate, or, for example, an additive based on aluminum hydroxide silicate, or, for example, an additive containing kaolin, reacts with impurities in heated industrial sand, thereby forming at least partially molten alkaline salts. Additionally, the heated industrial sand and at least partially molten alkaline salts are placed in a motion relative to each other, whereby at least some of the impurities remaining in the industrial sand adhere to the alkaline salts, thus forming grains. In more detail, at least some of the impurities remaining on the surface of a grain of industrial sand adhere to the alkaline salts, thus forming grains. Furthermore, grains agglomerate with the industrial sand and impurities and binders that exist in and / or are released from the industrial sand, thus forming grains, pellets, and increasingly larger agglomerated clusters.It should be mentioned that alkaline salts melt at least partially at a lower temperature than that of industrial sand, thus aiding in grain formation. It should also be mentioned that at least partially melted alkaline salts can be fully melted alkaline salts. For clarity, it should be mentioned that said alkaline salts release impurities onto the surface of the industrial sand, adhering to the impurities on the surface of the industrial sand, thus forming grains when combined, after which at least some of the grains are separated from the industrial sand. Petition 870250080613, dated 08 / 09 / 2025, pp. 70 / 94 6 / 20

[015] The additive may be based on aluminum silicate (Al2O3-SiO2). The additive may be based on aluminum hydroxide silicate Al2Si2O5(OH)4 (Al2O3^2SiO2^2H2O). The additive may comprise one of the following: andalusite, kaolin (H2Al2Si2O8 ·H2O), kyanite, and / or sillimanite. The aluminum silicate minerals of the additive to be added to the industrial sand are in their solid state. The additive may comprise a liquid, such as water, whereby the additive to be added to the industrial sand is in a liquid state, or in other words, whereby the additive to be added to the industrial sand is a suspension. The consistency of the additive is determined so that it melts at a higher temperature than the heated industrial sand. The melting point of the additive may be, for example, above 1000 °C.The additive is added to the industrial sand in such a quantity that there is, for example, 0.2-5.0 percent by weight of aluminum silicate minerals relative to the industrial sand, or, for example, 0.3-4.0 percent by weight relative to the industrial sand, or, for example, 0.5-3.0 percent by weight relative to the industrial sand. Alkaline salts or grains may be in their at least partially molten state, for example, at 500-850 °C, or for example, at least at 500-850 °C, or, for example, at least at 500-700 °C. The melting point of alkaline salts or grains may be, for example, at 700-1100 °C, or, for example, at 700-850 °C, or, for example, at least at 700-1100 °C.

[016] The industrial sand to be regenerated is pre-processed before being fed into the processing apparatus 300. The apparatus in the figures comprises a pre-processing apparatus 200. The pre-processing apparatus 200 comprises a crushing device 201 which is configured to crush pieces, such as molds, formed from industrial sand into smaller lumps of sand and industrial sand. The industrial sand is guided forward to a classification device 202 and lumps of sand are removed 201-R and possibly pre-processed again in the crushing device 201. The crushing device 201 may be, for example, a crusher. Petition 870250080613, dated 08 / 09 / 2025, pp. 71 / 94 7 / 20 rotary crusher, a roller crusher, an impact crusher, a jaw crusher, a hammer crusher, or a screw crusher.

[017] In addition, the pre-processing apparatus 200 comprises a classification device 202, which divides the industrial sand processed by the crushing device 201 into different quality classes, for example, by means of air classification. The quality classification may be based, for example, on the sand grain size. The industrial sand having a specific quality classification is guided to an industrial sand container 210 and the rest of the industrial sand and particles in it are removed 202-R for some other use or to be reprocessed. The classification device 202 may be connected, for example, to the crushing device 201 or the classification device 202 may receive, for example, sand processed by the crushing device 201, for example, by means of transport.

[018] Additionally, the pre-processing apparatus 200 comprises an industrial sand container 210 or, in other words, an industrial sand hopper 210, where crushed industrial sand having a specific quality class is stored for regeneration. The industrial sand container 210 can be connected to the classification device 202. The industrial sand container 210 comprises a feeder for supplying industrial sand forward.

[019] Additionally, the pre-processing apparatus 200 comprises a grinder 212 for grinding industrial sand. By means of the grinder 212, vibration is applied to the industrial sand, whereby mechanical grinding is applied to the industrial sand which assists in breaking down or releasing binders in the industrial sand from the industrial sand. Said grinder may be, for example, a substantially vertical column grinder which may comprise, for example, a rotating paddle or screw-like blade to produce said mechanical impacts on the industrial sand being processed, whereby both the impacts applied directly to the industrial sand by the paddle and the mutual grinding of sand grains that occurs from the industrial sand being ground release the binder and carbon possibly contained therein, from the Petition 870250080613, dated 08 / 09 / 2025, pp. 72 / 94 8 / 20 surface of sand grains. Alternatively, said grinder may be a substantially horizontal drum grinder comprising, for example, two drums rotating relative to each other within one another, whereby said drums produce mechanical impacts on the industrial sand that is fed between the furnaces, such that both the impacts applied directly to the industrial sand by the drums and the mutual grinding of sand grains on the industrial sand being ground, release the binder and carbon possibly contained therein from the surface of the sand grains. The grinder 212 may be connected to the industrial sand container 210. The released binder and carbon are removed 212-R and directed to some other use which is not further discussed in this context. Instead of the grinder 212 for grinding the industrial sand, the pre-processing apparatus 200 may comprise a friction means for grinding the industrial sand.Alternatively, grinder 212 can be a means of friction.

[020] Additionally, the pre-processing apparatus 200 comprises a metal separation apparatus 214 for removing metals from industrial sand. The metal separation apparatus 214 may comprise, for example, a conveyor and a magnet connected to the conveyor, the conveyor being configured to transport industrial sand to the feeder 220 and the magnet being configured to remove metals 214-R from industrial sand. The sand magnet may be called a magnet device. According to one embodiment, the feeder 220 described below is connected below the grinder 212, wherein the metal separation apparatus 214 is a magnet located in an area between the grinder 212 and the feeder 220, the magnet removing metals and other ferromagnetic substances from industrial sand as the industrial sand falls from the grinder 212 into the feeder 220.

[021] The apparatus in the figures comprises a feeder 220 for feeding industrial sand and additive into the processing apparatus 300. The feeder 220 is configured to receive previously processed industrial sand. In more detail, the feeder 220 is configured to receive processed industrial sand. Petition 870250080613, dated 08 / 09 / 2025, pp. 73 / 94 9 / 20 previously in the pre-processing apparatus 200. The feeder 220 of the figures comprises a conveyor 222. The conveyor 222 may be, for example, a belt conveyor, or the feeder may be, for example, a screw conveyor 222. Additionally, the feeder 220 may comprise an additive feeder 224 for adding the additive to the industrial sand in the conveyor 222. The additive feeder 224 is connected to the conveyor 222. By means of the feeder 220, the additive can be added to the industrial sand uniformly, or more specifically, by means of the feeder 220, the additive can be mixed with the industrial sand uniformly. The feed rate of the additive feeder 224 can be adjusted to achieve a suitable additive ratio.The speed of conveyor 222 can be adjusted so that the amount of industrial sand and additive being fed is appropriate in relation to the line speed of processing apparatus 300. According to one embodiment, feeder 220 can be a gravity-based feeder 220, wherein the industrial sand is dropped into the processing apparatus and wherein the feeder 220 supplies the additive at a specific ratio to the industrial sand falling into the processing apparatus.

[022] The processing apparatus 300 of the apparatus in the figures will be described in more detail below. The processing apparatus 300 comprises at least one inlet 302 for receiving industrial sand and additive.The processing apparatus 300 further comprises a heating device 310 configured to heat 300-H the industrial sand and the additive added to it, whereby the additive reacts with impurities, containing at least an alkali metal, in the industrial sand, thereby forming at least partially molten alkaline salts. The processing apparatus 300 further comprises means configured to place 300-M the industrial sand and the at least partially molten alkaline salts in a motion relative to each other, whereby at least some of the impurities remaining in the industrial sand adhere to the alkaline salts, thus forming grains. The processing apparatus 300 further comprises an outlet 304 for feeding the industrial sand and formed grains 300-F to a device for... Petition 870250080613, dated 08 / 09 / 2025, pp. 74 / 94 10 / 20 separation 400.

[023] The processing apparatus 300 of Figure 3 is a rotary kiln 300A or in other words a firing furnace 300A, or in other words a rotary kiln 300A or in other words, a rotary kiln 300A. The rotary kiln 300A comprises a vessel 303 where industrial sand is processed. The rotary kiln 300A, or in more detail the vessel 303 of the rotary kiln 300A, includes a first end 301A and a second end 301B. The first end 301A and the second end 301B are situated at opposite ends relative to each other. In more detail, the vessel 303 is a longitudinal hollow cylinder or a cylindrical construction.

[024] Additionally, rotary kiln 300A comprises an inlet 302 for receiving industrial sand and additive. Inlet 302 is connected to feeder 220. Inlet 302 is located near said first end 301A. Furthermore, rotary kiln 300A comprises an outlet 304 for feeding industrial sand and grains out of rotary kiln 300A. Outlet 304 is connected to separation device 400. Outlet 304 is located near said second end 301B. In Figure 3, inlet 302 and outlet 304 of rotary kiln 300A are located at opposite ends relative to each other.

[025] Additionally, the rotary kiln 300A comprises elevators 306 or in other words, paddles 306 or in other words vanes 306, which assist in placing the aforementioned industrial sand and alkaline salts in a moving motion inside the rotary kiln 300A. The elevators 306 are situated inside the rotary kiln 300A or more specifically inside the vessel 303. The elevators 306 are shaped so that they place the industrial sand and alkaline salts from the first end 301A towards the second end 301B of the rotary kiln 300A. When the rotary kiln 300A rotates, the elevators 306 lift the industrial sand until the industrial sand falls to a specific height from the vane 306 onto the bottom of the rotary kiln 300A, whereby the particles of the industrial sand collide with each other, which assists in releasing the binders in the industrial sand. Additionally, the fall Petition 870250080613, dated 08 / 09 / 2025, pp. 75 / 94 11 / 20 of the industrial sand from the 306 paddle on the bottom of the 300A rotary kiln helps the industrial sand receive thermal energy when thermal energy is applied to the falling industrial sand.

[026] The rotary kiln 300A further comprises a base 308, on top of which the rotary kiln 300A is situated, the base 308 of which is shown very schematically in Figure 3. By means of the base 308, the rotary kiln is adjusted to an angular position, or in other words inclination, relative to the horizontal plane, by means of which angular position it is possible to affect the propagation speed of industrial sand in the rotary kiln 300A. The base 308 can be an adjustable base 308 for changing the angular position of the rotary kiln. The angle between the rotary kiln 300A and the horizontal plane can be, for example, 0.5 - 5.0 degrees. The adjustable base 308 can operate, for example, hydraulically.

[027] Additionally, rotary kiln 300A comprises a heating device 310 for heating the industrial sand and the additive. The heating device 310 is configured to heat the industrial sand and the additive added to it by supplying thermal energy to the rotary kiln. The heating device 310 may comprise, for example, a burner, an electric resistor, a plasma source, or an induction device for supplying thermal energy to the rotary kiln, wherein the thermal energy may thus be, for example, combustion gas, heated air applied directly to the industrial sand, or heated air applied indirectly to the industrial sand through the constructions of the processing apparatus. The heating device 310 is connected to the first end 301A.

[028] The rotary kiln 300A further comprises an air exhaust device 320, through which thermal energy, air mass and exhaust gases and combustion dust possible in the air mass located in the rotary kiln 300A is removed 300-R. An exhaust gas filter to filter exhaust gases, a heat recovery system to recover heat and / or a dust filter to filter dust, may be connected to the exhaust device 320. In more detail, the exhaust filter of Petition 870250080613, dated 08 / 09 / 2025, pp. 76 / 94 The 12 / 20 air exhaust device is for removing solids from exhaust gases. The air exhaust device 320 is located at the opposite end from the heating device 310, or in other words, the air exhaust device 320 is located at the second end 301B of the rotary kiln 300A. This arrangement assists in applying thermal energy to industrial sand in an efficient manner.

[029] In addition, the rotary kiln 300A comprises a motor 330 for rotating the rotary kiln 300A. The motor 330 is configured to rotate the rotary kiln 300A and the elevators 306 contained therein to rotate the industrial sand, wherein the rotational speed of the rotary kiln 300A and the elevators may be, for example, 5 - 20 revolutions per minute (rpm). The rotation of industrial sand assists in supplying thermal energy to the industrial sand. The rotary kiln 300A comprises necessary means, such as, for example, bearings, toothed conveyors and / or gears connected to the motor 300 to enable the rotation of the rotary kiln 300A. The rotational speed of the motor 330 and thus of the rotary kiln 300A may be adjusted, wherein the rotational speed of the rotary kiln affects the speed of movement of industrial sand and, consequently, the magnitude of forces applied to the industrial sand.

[030] Additionally, rotary kiln 300A comprises a control unit 340 for adjusting the parameters of rotary kiln 300A and specifying the size of the grains thus formed. Control unit 340 can affect the industrial sand cycle time in rotary kiln 300A and the physicochemical reaction that occurs in industrial sand. Control unit 340 is shown very schematically in Figure 3 and is generally connected to rotary kiln 300A. The control unit is configured to control the amount of industrial sand received and additive added to it. Additionally, the control unit is configured to regulate the amount of thermal energy supplied by the heating device 310. Additionally, the control unit is configured to control the amount of air mass removed by the air exhaust device 320. Furthermore, the control unit is configured to adjust the angle of the rotary kiln relative to the level. Petition 870250080613, dated 08 / 09 / 2025, pp. 77 / 94 13 / 20 horizontal adjusting the position of the base 308. The control unit is additionally configured to manage the rotational speed of the rotary kiln 300A motor 330. The parameters of the rotary kiln 300A can be adjusted and thus affect the size of the grains to be formed, as mentioned above. The cycle time of industrial sand processed through the rotary kiln can be adjusted, for example, from 10-60 minutes. The size of the formed grains can be, for example, 3-10 mm, or for example, 4-8 mm, or for example, 5-6 mm.

[031] The apparatus in the figures comprises a separation device 400 configured to separate industrial sand to remove the grains from it. The separation device 400 is connected to the processing apparatus 300, or more specifically, the separation device 400 is connected to the output 304 of the processing apparatus 300. Industrial sand is separated from grains based on grain size, wherein in the separation, the grain size of industrial sand is smaller than the grain size of the grains. The separation device 400 may be a sieve, or in other words, a screen mesh with its mesh size being sized smaller than the grains formed, or in other words, the parameters used in the regeneration of industrial sand are adjusted so that the size of the grains to be formed is larger than the mesh size of the sized sieve. The separation device 400 may be a vibrating table comprising a screen of a specific size.Industrial sand with particle sizes below the specified size passes through the 400-S separation device, while industrial sand and formed grains with particle sizes above the specified size do not pass through the separation device. The industrial sand and formed grains that do not pass through the screen of the 400 separation device are removed by the 400-R and possibly further processed. In said further processing, the formed grains can be refined into secondary products, and the industrial sand in said further processing can be guided back, for example, to the 200 pre-processing apparatus or the 220 feeder of the apparatus. The mesh size of... Petition 870250080613, dated 08 / 09 / 2025, pp. 78 / 94 A 14 / 20 sieve can be, for example, 1-5 mm, or for example, 2-4 mm, or for example, about 2-3 mm.

[032] The apparatus of Figure 3 comprises a cooling furnace 500. The cooling furnace 500 comprises a container 503 in which the industrial sand is cooled. The cooling furnace 500, or more specifically its container 503, includes a first end 501A and a second end 501B. The first end 501A and the second end 501B are situated at opposite ends relative to each other. The container 503 is more specifically a longitudinal hollow cylinder or a cylindrical construction.

[033] Additionally, the cooling furnace 500 comprises an inlet 502 for receiving separated industrial sand. The inlet 502 is connected to the separation device 400 or more specifically, the inlet 502 is connected to the screen of the separation device 400 or in relation to it. The inlet 502 is located near said first end 501A. Additionally, the cooling furnace 500 comprises an outlet 504 for supplying the industrial sand out of the cooling furnace 500 to a classification device 600, wherein the outlet 504 is connected to the classification device 600, which will be described in more detail below. The outlet 504 is located near said second end 501B. In other words, the inlet 502 and the outlet 504 are located at opposite ends relative to each other.

[034] Additionally, the cooling furnace 500 comprises a base 508 on top of which the cooling furnace 500 is situated, which base 508 is shown very schematically in Figure 3. By means of the base 508, the cooling furnace is adjusted to an angular position relative to the horizontal plane, which angular position can affect the propagation speed of industrial sand in the cooling furnace 300A. The base 508 can be an adjustable base 508 to change the angular position of the cooling furnace. The adjustable base 308 can operate, for example, hydraulically.

[035] In addition, the cooling oven 500 comprises a device for Petition 870250080613, dated 08 / 09 / 2025, pp. 79 / 94 15 / 20 Air supply 520 to supply cooling air to the cooling furnace to release latent thermal energy that exists in industrial sand from the industrial sand. The cooling furnace is configured to cool 500-C industrial sand by supplying cooling air to the cooling furnace 500. The cooling air can be air at the temperature prevailing in a space outside the cooling furnace. The air supply device 520 is located at the second end 501B of the cooling furnace. Supplying cooling air to the cooling furnace causes the temperature of the industrial sand to decrease, which aids in the release of binder residues from the industrial sand.

[036] In addition, the cooling furnace 500 comprises an air exhaust device 530 for receiving cooling air and for receiving thermal energy released from the industrial sand, through which air exhaust device, the cooling air flowing through the cooling furnace 500 and any dust contained therein are removed. The air exhaust device 530 is configured to remove 500-R mass of air and any dust contained therein from the cooling furnace. The air exhaust device 530 is situated at the opposite end with respect to the air supply device 520, or in other words, the air exhaust device 53 is situated at the first end 501A of the cooling furnace 500. A dust filter may be connected to the air exhaust device 530 to filter dust and various binder residues, and a thermal energy recovery system may be connected to the air exhaust device 530 to recover thermal energy.

[037] The cooling furnace 500 further comprises grinding spheres 530 for grinding the cooled industrial sand and thereby releasing the remaining binder residues from the industrial sand. The grinding spheres 540 may, in other words, be crushing balls 540. Grinding may, in other words, be crushing. The cooling furnace comprises a grinding compartment 505A, where the grinding spheres 540 are arranged. The grinding compartment 505A starts from the first end 501A of the cooling furnace 500 and extends to a specified distance from said first end 501A. Petition 870250080613, dated 08 / 09 / 2025, pages 80 / 94 16 / 20 The grinding compartment 505A can be separated from the other part of the cooling furnace, for example, by means of a wall baffle with openings located inside the cooling furnace. Industrial sand is ground 540-M by grinding balls. Grinding industrial sand with grinding balls 540 and simultaneous cooling of industrial sand helps to release binders remaining in the industrial sand from the industrial sand. The industrial sand in the cooling furnace has already been ground once in the rotary kiln and, additionally, the temperature of the industrial sand in the cooling furnace is colder than the industrial sand in the rotary kiln, so the uniform grinding applied to the industrial sand is different from the uniform grinding that occurs in the rotary kiln, which helps to release the binders remaining in the industrial sand from the industrial sand.

[038] The cooling furnace 500 further comprises elevators 550, or in other words paddles 550, which assist in setting the industrial sand in motion within the cooling furnace 500. The elevators 550 are shaped so that they accompany the industrial sand from the first end 501A of the cooling furnace 500 towards the second end 501B. The elevators 550 are situated in a paddle compartment 505B, wherein the paddle compartment 505B is at a specific distance from the grinding compartment 505A extending a specific distance from the second end 501B of the cooling furnace 500.When the cooling furnace 500 rotates, the elevators 550 raise the industrial sand until the industrial sand falls to a specific height from the paddle 550 onto the bottom of the cooling furnace 500, which helps the industrial sand release thermal energy into the cooling air flowing through the industrial sand. Additionally, the falling of industrial sand onto the bottom of the cooling furnace causes collisions of the industrial sand particles against each other, which helps release binders from the industrial sand.

[039] Additionally, the cooling furnace 500 comprises a motor 560 for rotating the cooling furnace 500. The cooling furnace 500 comprises means Petition 870250080613, dated 08 / 09 / 2025, pages 81 / 94 17 / 20 required, such as bearings, toothed conveyor rings and / or gears connected to motor 560 to rotate cooling furnace 500.

[040] The apparatus of the figures comprises a classification device 600 configured to classify 600-F industrial sand, which industrial sand has been thermomechanically processed in the rotary kiln 300A, and which industrial sand has been further mechanically processed, i.e., by grinding in the cooling furnace 500. The classification device 600 comprises at least one screen for classifying the industrial sand based on grain size. The classification device 600 thus comprises a first screen with a specific mesh size. The industrial sand that passes through the first screen forms the first quality class of industrial sand. Additionally, industrial sand that has passed through the first screen can be guided to a second screen with a specific mesh size smaller than the first screen. The industrial sand that has passed through the second screen forms the second quality class of industrial sand.The sorting device may comprise n number of screens (n ​​= 1, 2, 3, 4, 5...). The industrial sand that did not pass through the first screen is removed 600-R for some other use or guided, for example, to reprocessing or to feeder 220. The mesh size or mesh sizes of the screen may be, for example, 0.1 mm, 0.2 mm, 0.5 mm and / or 1.0 mm.

[041] The apparatus in Figure 3 comprises a post-processing device 700 which may be, for example, a storage, transport or industrial processing device for industrial sand.

[042] The processing apparatus 300 of the apparatus in Figure 4 is a fluidized bed reactor 300B. The fluidized bed reactor comprises an inlet 302 and an outlet 304. The fluidized bed reactor 300B is configured to receive industrial sand and additive from feeder 220. The fluidized bed reactor 300B comprises a heating device 310 for heating the industrial sand and additive added to it. The heating device 310 may be, for example, a gas combustion device. The heating device 310 puts the heated industrial sand and alkaline salts into motion that occurs in relation to Petition 870250080613, dated 08 / 09 / 2025, pages 82 / 94 18 / 20 to the other, so that at least some of the remaining impurities adhere to the alkaline salts, thus forming grains. The fluidized bed reactor 310B comprises a processing device 320B, such as a cyclone, through which burned gases are guided in the process for further gas processing and through which the industrial sand and formed grains are guided to the separation device 400. It is additionally possible to connect the cooling furnace 500, the classification device 600 and / or the post-processing device 700 to the apparatus of Figure 4, however these are not shown in Figure 4 for clarity.

[043] According to a first example, the following arrangement was implemented to regenerate industrial sand. The industrial sand is phenolic resin sand, that is, sand bound with organic resins, which was regenerated using feeder 220, rotary kiln 300A and separator 400 of Figure 3. Phenolic resin sand comprises carbon and alkali metal as binders, wherein the alkali metal comprises potassium. An additive is added relative to the industrial sand so that there is about 1 percent by weight of kaolin to the industrial sand. The industrial sand and the additive added to it are heated to 500-850 °C, whereby the additive reacts with impurities, comprising at least alkali metal, in the industrial sand forming at least partially molten alkali salts. In said temperature range, carbon in the phenolic resin sand burns.Industrial sand and alkaline salts are placed in a motion relative to each other, whereby at least some of the impurities remaining in the industrial sand adhere to the alkaline salts, thus forming grains, the size of which is approximately 5-10 mm. The rotation speed of the 300A rotary kiln is approximately 5-20 rpm, and the angular position of the 300A rotary kiln relative to the horizontal level is approximately 0.5-5.0 degrees, so the industrial sand is thermomechanically processed for approximately 10-60 minutes. When the loss of ignition of industrial sand after thermomechanical processing is approximately 1.5 percent, the pH value of industrial sand is approximately 10-11 and its electrical conductivity is approximately 1000 EC. Petition 870250080613, dated 08 / 09 / 2025, pages 83 / 94 19 / 20

[044] According to a second example, an arrangement corresponding to the first example is implemented, however there is about 1.5 percent by weight of kaolin in the additive relative to the industrial sand. When the loss of ignition of industrial sand after thermomechanical processing is about 1.5 percent, the pH value of industrial sand is about 9.0 - 9.5 and its electrical conductivity is about 400 EC.

[045] According to a third example, an arrangement corresponding to the first example is implemented, however there is about 2.0 percent by weight of kaolin in the additive relative to the industrial sand. When the loss of ignition of industrial sand after thermomechanical processing is about 1.5 percent, the pH value of industrial sand is about 7.5 - 8.2 and its electrical conductivity is about 200 EC.

[046] According to a fourth example, an arrangement corresponding to the first example is implemented, however the industrial sand is green sand comprising bentonite and alkali metal as binders, wherein the alkali metal comprises potassium. For clarity, it should be mentioned that the additive is added to the industrial sand so that there is about 1 percent by weight of kaolin in the additive relative to the industrial sand. When the loss of ignition of industrial sand is about 1.5 percent, the pH value of industrial sand is about 8.4 and its electrical conductivity is about 150 EC.

[047] According to a fifth example, an arrangement corresponding to the fourth example is implemented, however there is about 1.5 percent by weight of kaolin in the additive relative to the industrial sand. When the loss of ignition of industrial sand after thermomechanical processing is about 1.5 percent, the pH value of industrial sand is about 8.0 and its electrical conductivity is about 100 EC.

[048] According to a sixth example, an arrangement corresponding to the fourth example is implemented, however there is 2.5 percent by weight of kaolin in the additive relative to the industrial sand. When the loss of ignition of industrial sand after thermomechanical processing is about 1.5 percent, the pH value of industrial sand is about 7.4 and its electrical conductivity is about 30 EC.

[049] People versed in the technique will find it obvious that, as the Petition 870250080613, dated 08 / 09 / 2025, pages 84 / 94 As technology advances, the basic idea of ​​the invention can be implemented in many different ways. The invention and its embodiments are therefore not limited to the examples described above, but may vary in the scope of the claims. Petition 870250080613, dated 08 / 09 / 2025, pages 85 / 94

Claims

1 / 4 CLAIMS 1. Method for regenerating industrial sand, wherein the method is characterized by adding (110) an aluminum silicate-based additive to the industrial sand, heating (120) the industrial sand and the additive added thereto, wherein the additive reacts with impurities, comprising at least alkali metal, in the industrial sand forming at least partially molten alkaline salts, placing (130) the heated industrial sand and the alkaline salts in a motion that occurs relative to each other, wherein at least part of the remaining impurities in the industrial sand adhere to the alkaline salts forming grains and separating (140) the industrial sand to remove grains from the industrial sand.

2. Method according to claim 1, wherein the method is characterized by placing (130) heated industrial sand and alkaline salts in a motion relative to each other in a rotary kiln (300A) thus assisting in the formation of grains.

3. Method according to claim 1 or 2, wherein the method is characterized by heating the industrial sand and the additive added to it to 500–850 °C.

4. Method, according to any one of claims 1 to 3, wherein the method is characterized in that, during the heating of industrial sand and the additive added to it, the additive reacts with impurities, comprising at least an alkali metal, in the binders of the industrial sand, thus forming at least partially molten alkaline salts, and wherein the method places the heated industrial sand and the alkaline salts in a motion that occurs relative to each other, and at least part of the impurities remaining on the surfaces of the sand grains of the industrial sand adhere to the alkaline salts, thus forming grains. Petition 870250080613, dated 08 / 09 / 2025, page 86 / 94 2 / 4 5. Method, according to any one of claims 1 to 4, wherein the method is characterized in that the industrial sand is green sand.

6. Method, according to any one of claims 1 to 4, wherein the method is characterized in that the industrial sand comprises organic resin as a binder.

7. Method, according to any one of claims 1 to 6, wherein the method is characterized by separating the grains formed from industrial sand based on grain size.

8. Method, according to any one of claims 1 to 7, wherein the method is characterized by further cooling (150) the industrial sand to assist in the release of binders remaining in the industrial sand, grinding (160) by grinding spheres (540) the cooled industrial sand to release the binders remaining in the industrial sand from the industrial sand and sieving (170) the industrial sand to classify the industrial sand based on grain size.

9. Method, according to any one of claims 1 to 8, wherein the method is characterized in that the additive comprises one of the following aluminum silicate minerals: andalusite, kaolin, kyanite or sillimanite.

10. Apparatus for regenerating industrial sand according to the method as defined in any one of claims 1 to 9, wherein the apparatus is characterized by comprising a feeder (220) for feeding industrial sand and an additive, a processing apparatus (300), a processing apparatus (300) for heating the industrial sand and the additive added thereto, and additionally for placing the industrial sand and the additive added thereto in a motion that occurs relative to each other, and a separation device (400) configured for separating industrial sand to remove grains from the industrial sand. Petition 870250080613, dated 08 / 09 / 2025, pp. 87 / 94 3 / 4 11. Apparatus, according to claim 10, characterized in that the feeder (220) comprises a conveyor (222) for receiving industrial sand and further guiding it to the processing apparatus (300), wherein the conveyor (222) is connected to the processing apparatus (300) and an additive feeder (224) for adding the additive to the industrial sand in the conveyor (222).

12. Apparatus according to claim 11, characterized in that the conveyor (222) is a helical conveyor.

13. Apparatus, according to any one of claims 1 to 12, characterized in that the processing apparatus (300) is a rotary kiln (300A) comprising an inlet (302) connected to the feeder (220), a heating device (310) configured to heat the industrial sand and the additive in the rotary kiln (300A), a motor (330) configured to rotate the rotary kiln to place the industrial sand and the additive added to it in a motion that occurs relative to each other, a control unit (340) to adjust the parameters of the rotary kiln (300A) and to specify the grain size to be formed and an outlet (304) connected to the separation device (400).

14. Apparatus, according to any one of claims 1 to 13, characterized in that the separation device (400) is a screen that separates grains from industrial sand based on grain size.

15. Apparatus, according to any one of claims 1 to 14, wherein the apparatus is characterized by further comprising a cooling furnace (500), wherein the cooling furnace (500) comprises an inlet (502) connected to the separation device (400) for receiving separated industrial sand, Petition 870250080613, dated 08 / 09 / 2025, p. 88 / 94 4 / 4 an air feed device (520) for supplying cooling air to the cooling furnace to release thermal energy from the industrial sand, an air exhaust device (530) for receiving cooling air and for receiving thermal energy released from the industrial sand, grinding balls (540) for grinding the cooled industrial sand to release remaining binders in the industrial sand, a motor (560) for rotating the cooling furnace, grinding balls and the industrial sand and an outlet (504) for supplying the industrial sand forward.

16. Apparatus according to claim 15, wherein the apparatus is characterized by comprising a sorting device (600) connected to the outlet (504) of the cooling furnace (500), the sorting device (600) comprising at least one screen for sorting industrial sand based on grain size. Petition 870250080613, dated 08 / 09 / 2025, pp. 89 / 94

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