Field

The invention relates to inorganic solid material processing method and apparatus. Background

Mineral wool products and certain other inorganic solid materials naturally include ammonia. Moreover, ammonia may be added to mineral wool products during a manufacturing phase.

Alkali activation, for example, results in a strong smell of ammonia if such a process is applied to mineral wool waste or the like because ammonium is released into air. The Permissible Exposure Limit for ammonia set by Occupational Safety and Health Administration (OSHA) is 50 parts per million (ppm) averaged over an eight-hour work day. The harmful release of ammonia from the mineral wool waste or the like can exceed the limit and thus prevent recycling and use of mineral wool waste as a precursor for alkali activated materials (AAMs) or as supplementary cementitious material (SCMs), for example. The release of ammonia may continue also after the manufacturing phase based on recycled mineral wool products or the like, which exposes not only the workers but potentially people in general to ammonia. Ammonia may also react in an undesirable manner with other substances during a manufacturing phase of a product or even after that if utilization of the recycled mineral wool or the like were attempted as a raw material. Ammonia can decrease strength development, durability and/or length of service of the AAMs or SCM products, for example.

Therefore, mineral wool waste or the like poses an insurmountable recycling challenge and is due to that currently landfilled.

Brief description

The present invention seeks to provide an improvement in the processing. The invention is defined by the independent claims. Embodiments are defined in the dependent claims.

If any of the embodiments does not fall under the scope of the independent claims, such an embodiment should to be interpreted as useful example for understanding features of the invention.

List of drawings

Example embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which Figure 1A and IB illustrate examples of an apparatus for processing inorganic solid material that includes ammonia or nitrogen containing compounds that could form ammonia by chemical reactions;

Figure 2 illustrates an example of breaking and/or mixing fluid and inorganic solid material; Figures 3A and 3B illustrate examples of abrasion; and

Figure 4 illustrates of an example of a flow chart of a processing method.

Description of embodiments

The following embodiments are only examples. Although the specification may refer to "an" embodiment in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such embodiments may also contain features/structures that have not been specifically mentioned. All combinations of the embodiments are considered possible if their combination does not lead to structural or logical contradiction.

It should be noted that while Figures illustrate various embodiments, they are simplified diagrams that only show some structures and/or functional entities. The connections shown in the Figures may refer to logical or physical connections. It is apparent to a person skilled in the art that the described apparatus may also comprise other functions and structures than those described in Figures and text. It should be appreciated that details of some functions, structures, and the signalling used for measurement and/or controlling are irrelevant to the actual invention. Therefore, they need not be discussed in more detail here.

Mineral wool products and certain other inorganic solid materials contain organic resins, typically urea-modified phenol formaldehyde without limiting to this. The possible organic resin types include, but not limit to, phenolic resin, polyesters, melamine-urea-formaldehyde, polyamides, furan-based resin, and sugar-based resin. Ammonia is typically added during manufacture and amide/ nitrogen containing compounds in the organic resin structure like urea in phenolic-urea formaldehyde and melamine urea formaldehyde, amide in polyamides etc. may be added.

Figs. 1A and IB illustrate examples of an apparatus for processing inorganic solid material that includes ammonia. In an embodiment, the inorganic solid material may include mineral wool.

In Fig. 1A, the apparatus comprises a break unit 100, which receives the inorganic solid material and breaks the structure of the inorganic solid material. The inorganic solid material includes ammonia or one or more nitrogen compound. The ammonia and at least one nitrogen compound may be infiltrated in the inorganic solid material as free ammonia or as part of organic phenol- formaldehyde resin, for example. Although Fig. 1 shows only one break unit 100, there may be more than one break unit 100 in general.

The apparatus of Fig. 1A also comprises at least one treatment unit 102, which receives the inorganic solid material, which has been processed in the break unit 100, and treats the inorganic solid material with fluid, which includes water, for hours. Then the inorganic solid material is dried. Ammonia emission of the inorganic solid material is reduced after this kind of processing. Temperature or a temperature range may be above melting point of water during the fluid interacts with the inorganic solid material. In the treatment, the fluid and the inorganic solid material touch each other physically or interact physically. During the treatment, ammonium reacts chemically with water, and ammonium of the inorganic solid material becomes ammonium hydroxide. The ammonium hydroxide, in turn, solves into the fluid and ammonium is removed from the inorganic solid material.

Before treating the inorganic solid material in a humid condition, the inorganic solid material may be treated in an elevated temperature, i.e. in an oven, about 70°C to about 100°C for 5 h or less. The decision whether the inorganic solid material should be treated in an elevated temperature before the exposing it to humidity depends on the material response towards the process types, whichever is more efficient is chosen for the treatment of that material. The decision of use of the oven may be based on a test or experience, for example.

In an embodiment, the temperature or the temperature range of the fluid with which the inorganic solid material interacts may be about 0°C to about 100°C, for example. In an embodiment, the temperature or the temperature range of the fluid with which the inorganic solid material interacts may be about 20°C to about 30°C, for example. In an embodiment, the temperature or the temperature range of the fluid with which the inorganic solid material interacts may be about 20°C to about 70°C, for example. In an embodiment, the temperature or the temperature range of the fluid with which the inorganic solid material interacts may be about 70°C to about 100°C, for example.

The ammonia formation is likely related to the depolymerization of the organic binder, more specifically hydrolysis of amide, methylene ether, and methylene linkages between urea groups without limiting to this possibility. In an embodiment, the water of the fluid may be in a liquid phase. In an embodiment, the water of the fluid may be in a vapor phase. In an embodiment, the water of the fluid may be in both a liquid phase and in a vapor phase. The phases of the water during the treatment or within the treatment unit 102 may be controlled by total amount of water, pressure and temperature, for example. In an embodiment, the fluid may be steam. Fig. IB illustrates an example of the apparatus, which comprises a combined breaking and treatment unit 104. In general, at least one treatment unit 102 treats the inorganic solid material with the fluid simultaneously with or after the breaking the structure of the inorganic solid material. In an embodiment, the treatment unit 102 and the combined break and treatment unit 104 may be container or a tank within which gas, vapor or liquid can be inserted and kept. In similar manner the break unit 100 may be container within which the inorganic solid material can be inserted and broken. The breaking in the break unit 100 or in the combined break and treatment unit 104 may be performed mechanically.

In an embodiment, the duration of the treatment and the size of particles, which the inorganic solid material is broken into, may depend on each other. Larger particles sizes may be treated for a longer time. Correspondingly, the smaller the particles of the inorganic solid material are, the shorter the duration of treatment may be. That is, the particle size and the duration of the treatment may be directly proportional to each other.

In an embodiment, the water may be tap water i.e. water from the system of water pipes, for example. In an embodiment, the water may be natural water of a lake, river, sea or rain, for example. In an embodiment, the water may be technically purified water such as distilled water.

In an embodiment, duration of the treatment may be about one day, for example. In an embodiment, duration of the treatment may be about two days, for example. In an embodiment, duration of the treatment may be about a plurality of days, for example. In an embodiment, duration of the treatment may be about one week, for example. In an embodiment, duration of the treatment may be about ten days, for example. In an embodiment, the treatment may last least the length mentioned above.

For glass wool, the process may include grinding in order to break the glass wool into pieces or powder, and exposure to the fluid in a suitable temperature or temperature range. For stone wool, the process may include grinding in order to break the stone wool into pieces or powder, and exposure to the fluid in a suitable temperature or temperature range.

In an embodiment, the inorganic solid material may be inside a humid environment, the moisture being caused by water. The moisture may a gas phase of water or water vapor, or water may have condensed and made tiny liquid water droplets that do not fall down by the gravitational force. In such a case, the inorganic solid material is inside fog. In addition to water, the moisture may include other substances in addition to water. In that manner, water consumption can be reduced (at least with respect to immersion). The humidity should be in a range about 90% to 100%. For example, lOOg of the inorganic solid material has typically adsorption less than about 10 g of water or to maximum of about 20 g. The inorganic solid material may adsorb about 10% to 20 % of the humidity.

In an embodiment, stopping the treatment with the fluid is stopped, and the fluid is removed from the inorganic solid material that is structurally broken. In an embodiment, the fluid may be removed from the inorganic solid material by drying, for example. In an embodiment, the inorganic material may be dried in temperature that is higher than a normal temperature (293.15K) of the NTP (Normal Temperature and Pressure) in chemistry. In an embodiment, the temperature or the temperature range for drying may be about 50°C to about 200°C, for example. In an embodiment, the temperature range for drying may be about 70°C to about 100°C for example. In an embodiment, the temperature range for drying may be about 120°C to about 100°C, for example. In an embodiment, the temperature range for drying may be about 120°C to about 200°C, for example. During drying phase a good ventilation or collection of gas phase of ammonia may be required.

In an embodiment, the treatment phase with the fluid and drying phase may be repeated one after another a plurality of times. In an embodiment, at least two treatments with the fluid may be performed with different fluid. In an embodiment, at least two treatments with the fluid may be performed with different fluid. In an embodiment, at least two treatments with the fluid may be performed in different temperatures. In an embodiment, at least two drying phases may be performed in different temperatures. In an embodiment, the temperature or the temperature range of the treatment may depend on the fluid of the treatment. In an embodiment, the temperature or the temperature range of the drying phase may depend on the fluid of the treatment.

In an embodiment, the fluid may be removed from the inorganic solid material by applying centrifugal force to the inorganic solid material, for example. In such a case, the inorganic solid material that is treated with the fluid may be inserted in a centrifuge and kept in the centrifuge switched into operating state for a period of time.

In an embodiment, the fluid may be removed from the inorganic solid material by filtering, for example. In such a case, the inorganic solid material that is treated with the fluid may be filtrated to separate the solid and the fluid.

In an embodiment applying to Fig. 1A, the structure of the inorganic solid material is first broken in the break unit 100. After that the inorganic solid material, which is structurally broken, is mixed with the fluid for exposing all surfaces of the inorganic solid material equally to the fluid.

In an embodiment, at least surface of the inorganic solid material may undergo abrasion in the break unit 100. In an embodiment an example of which is illustrated in Fig. 2, the breaking of the inorganic solid material may be performed mechanically. The inorganic solid material may be broken by grinding, milling, comminuting, crushing, beating, cutting, tearing, bending, winding, applying abrasion or friction, or using any combination of these or the like, for example. In an embodiment, the breaking mechanism 200 may comprise steel balls or steel rods 208 in a milling jar or applying pressure, abrasion or friction in a container or at least one blade 202 that moves up and down and/or rotates, and breaks the solid material. Alternatively or additionally, the breaking mechanism 200 may comprise rolls 204, 206 between which the inorganic solid material is forced to travel, the pressure between the rolls 204, 206 breaking the inorganic solid material into pieces. In an embodiment an example of which is illustrated in Fig. 3A, abrasion between surfaces of at least two pieces 300, 302 of the inorganic solid material is applied for breaking at least the surface of the pieces 300, 302 of the inorganic solid material. If there are more than one piece 300, 302 of the inorganic solid material in the break unit 100 or the combined break and treatment unit 104, the pieces 300, 302 may be mechanically moved using mixing or the like within the break unit 100 or the combined break and treatment unit 104. Then the movement causes the pieces 300, 302 of the inorganic solid material touch each other during movement which results in abrasion and breakage of at least surface of the pieces 300, 302 of the inorganic solid material.

In an embodiment an example of which is illustrated in Fig. 3B, abrasion between at least one abrasive surface 204 and at least one piece 300 of the inorganic solid material is applied for breaking at least the surface of the inorganic solid material. When a piece 300 of the inorganic solid material in the break unit 100 or the combined break and treatment unit 104 is mechanically moved using mixing or the like within the break unit 100 or the combined break and treatment unit 104, the movement causes the piece 300 of the inorganic solid material touch the abrasive surface 204 during movement which results in abrasion and breakage of a surface of the piece 300 of the inorganic solid material.

Abrasion increases surface roughness which, in turn, increases surface area and improves the contact between the ammonia or nitrogen containing compounds and water. Surface roughness may also include at least one fracture or crack such that the inorganic solid material is not broken into completely separate parts. Alternatively or additionally, abrasion may cause a piece of the inorganic solid material break into two or more separate parts or sub-pieces.

In an embodiment, the inorganic solid material may be milled into pieces. In an embodiment, the inorganic solid material may be wet-milled into pieces. Then, the break unit 100 or the combined break and treatment unit 104 comprises a mill, which a person skilled in the art is, perse, familiar with.

In an embodiment, the break unit 100 may break the inorganic material into pieces a diameter of which may be less than about 5mm, for example. In an embodiment, the break unit 100 may break the inorganic solid material into pieces a diameter of which may be less than about 1mm, for example. In an embodiment, the break unit 100 may break the inorganic material into pieces a diameter of which may be less than about 0.5mm, for example. For agglomerates of mineral wool particle size could be 5 cm to 0.5 mm in diameter. As individual fibre length it could be 20-500 micrometers in an embodiment. In an embodiment, an individual fibre length could be 10-100 micrometers, for example.

In an embodiment, the break unit 100 may break the inorganic material into pieces a diameter of which may be less than about 20-500 micrometers. In an embodiment, the diameter may be less than about 50 micrometers on average. In an embodiment, an individual fibre length may be less than about 100 micrometers, for example. However, the fiber length may be less than about 50 micrometers, for all or at least almost all fibers. The small particles of the inorganic solid material have a large surface which helps the adsorption of water vapor. In other words, milled mineral wool has large surface area and hence also high extent of reaction with the treatment.

In an embodiment, the inorganic solid material may be broken into powder such that it becomes inorganic solid material powder.

In an embodiment, the inorganic solid material may be treated with fluid that is a mixture of water and at least one of the following: organic solvent such as ethanol, methanol or some other alcohol, acetone, mineral acid, organic acid, or peroxide. The fluid may also be an alkaline solution.

In an embodiment, the inorganic solid material may be treated with fluid that is gas with relative humidity at least 50%. In an embodiment, the gas is air of the atmosphere.

In an embodiment, the inorganic solid material may be treated with fluid that is gas with relative humidity at least 70%.

In an embodiment, the inorganic solid material may be treated with fluid that is gas with relative humidity at least 90%. In an embodiment, the inorganic solid material that is structurally broken may be input into a process including alkali activation after treating the inorganic solid material with the fluid.

In this simple manner, a precursor can be formed, the precursor being utilizable in a production of consequent material of a higher value. The consequent material may be alkali activated material which is often also called a geopolymer or used as supplementary cementitious material or used as fibre reinforcement in composite materials, or as brick raw material, or as briquette raw material to be used as recycled raw material in mineral wool manufacturing, for example. This way of treating the inorganic solid material practically avoids production of sludge. That means, the inorganic solid material does not dissolve which can affect the cementitious properties. It should also be noted that formation of zeolite or any other delirious surface precipitates or phases are significantly reduced or non existent. This has a technical advantage that material needs to be not modified as various mix composition for different application differs (manufacturer’s desire for certain quality).

Figure 3 is a flow chart of the measurement method. In step 400, breaking structure of the inorganic solid material, which includes ammonia or one or more compound including nitrogen. In step 402, the inorganic solid material is treated with fluid including water in a temperature or temperature range above melting point of ammonia, simultaneously with or after the breaking the structure of the inorganic solid material, for hours in order to reduce ammonia emission of the inorganic solid material after the treatment.

As some general notes it should be understood that when mineral wool is kept in the humid chamber as the next step following grinding after 1 day or so, smell of ammonia is in the air, and the powder will be somewhat wet. This is typically observed in all the cases of glass wool. But some stone wools did not react with humidity even after 7 days. This may be caused by the hydrophobic mineral oil coating. So, after grinding the powder is heated at 50- 100° C for about 2 h to 5 h and then kept in humid chamber. This made the material to react with humid. A few examples of test that have been carried out and that can be carried out for removing or lowering ammonium (NH3) emissions.

In method 1, the inorganic solid material is ground in a metal container and kept in humidity about 94% to 97% for 7 days and then dried in temperature about 50°C-100°C. After this treatment, the powder is alkali activated. Measurement of ammonia with a NH ₃ -detection meter is performed. The result is compared with alkali activation of mineral wool without this treatment. Loss on ignition is done and the results showed that some amount of organic resin is destructed due to this treatment and NH3 has been removed at least almost fully. In method 2, the inorganic solid material is ground in metal container.

Then a following cycle is repeated a plurality of times: the inorganic solid material is kept in humidity about 94% to 97% for 1 day and then dried in temperature about 50°C-100°C. After cycling, the powder of the inorganic solid material is alkali activated. Results showed that ammonia removal occurred at least almost fully. In method 3, the glass wool is ground in metal container. Then the ground glass wool is kept in humidity about 94% to 97% for 1 day and dried for 2 h in temperature about 100°C- 200°C. Stone wool is ground in metal container. Then the ground stone wool is kept in humidity about 94% to 97% and dried for 2 h in temperature 100°C- 200°C. In method 4, glass wool and stone wool are ground. Then the ground glass and stone wool are kept in humidity about 94% to 97% for 1 to 7 days. Drying is performed in temperature about 100°C. In this method, when the material has dried, water may be added/humidity may be increased again and the drying process may be repeated. In method 5, the inorganic solid material is ground. Then the ground material is exposed to pure solvent such as isopropanol, ethanol, acetone, cyclohexene, peroxide, or a mixture of solvents or a mixture of water and at least one solvent for 1 day to 7 days. Then the ground solid material is separated from the solvent by filtering or pouring the solvent out once the inorganic solid material is settled in the bottom. Finally the inorganic solid material is dried in temperature about 100°C. In method 6, the inorganic solid material is ground. Then the ground material is exposed to a mixture of solvent and water for about 1 day to 7 days. Then the ground inorganic solid material is filtered or the mixture is poured out. Finally the inorganic solid material is dried in temperature about 100°C. In method 7, the inorganic solid material is milled with 10 - 40 % quartz during milling. During milling, the milled material may turn grey to black. After that alkali activation is realized.

In method 8: the inorganic solid material is ground with quartz. Then the ground inorganic solid material is pre-treated with humidity about 94% to 97% for 7 days. Then the ground solid material is dried for about 0.5 days to 1 day and alkali activation is performed.

In method 9: the inorganic solid material is milled and kept in humid chamber for seven days. Then the inorganic solid material is exposed to a heat treatment of about 75°C for about 5 h at maximum. In general, the treatment in an elevated temperature should not last longer than 24 h.

The process is not intensive, cost effective and easy with clear and well defined process steps.

In order to break the inorganic solid material into pieces milling may be dry-milling or wet-milling. Milling the inorganic solid material may be performed in set temperature or humidity conditions. Exposure to the fluid may be performed in a climatic chamber with fixed or deterministically varying humidity and temperature. Ammonium (NH3) is at least partially removed so that during the initial time of alkali activation, the workers can work with it without any trouble. The ammonia emission may be measured during and/or after the whole treatment. When a suitable level of emission is reached, the process may be stopped. Alternatively or additionally, material surface morphology after the treatment may be checked whether any surface precipitates formed on the material surface due to the process. The treatment process may be compatible for the treatment of glass wool and stone wool, although it may be utilized for other inorganic solid materials, too. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the example embodiments described above but may vary within the scope of the claims.