FI119475B - A process for preparing a useful product from a slurry - Google Patents

Description

119475

Process for the preparation of a recovery product from sludge Förfarande för tillverkning av en nyttoprodukt av slam

The present invention is directed to a process for the preparation of a finely divided particulate utility product from a digestion slurry as set forth in the preamble of independent claim 5 below.

Municipal waste, waste from livestock farms and waste from, for example, the food industry as well as sewage sludge from sewage treatment plants contain very large amounts of useful organic and inorganic substances 10 that can be used as soil improvers. However, waste is generally not available as such. In the past, organic / biological wastes have generally been composted to be recycled. Composting is time consuming and therefore requires a large space.

It is also known to treat the aforementioned wastes by digesting with anaerobic bacteria so-called. bioreactors. The biogas produced by decomposition can be used for energy production. Digested sludge or digestate sludge from digestion • · · V * 'contains a large amount of nitrogen, phosphorus and potassium, substances which can be used as plant nutrients. On the other hand, some sludges may contain toxic substances, · ·: making them unsuitable for such use.

* ·· • · • • · *.:. 20 The sludge from digestion is usually immediately dried to a dry matter content of about 20-30%. Drying is typically done using screw dryers or spin dryers.

···. . Solids from digestion can be composted into soil improvers, which • ♦ · however, takes quite a bit of time and thus also requires a lot of storage space.

• · · · · · · · · · · · · · · · · Composting of digested sludge is hampered by its composition. The slurry is mainly • · '* ··] 25 slurry-like, sticky, sticky materials. Therefore, sludge is before. * composting mixing litter to make the slurry airy. Litter • * ·: · is mixed, for example, by adding sludge to the litter pile and mixing the pile with a bucket loader. The finished mixture is stored in folds, which are rotated from time to time. Storage may take years. Of course, mixing with a bucket loader 2 119475 is not the optimal way to mix caked material. Therefore, such composting often causes odor problems as anaerobic reactions continue inside the lumps.

It is an object of the invention to provide an improved process for the preparation of a useful product 5 from digestion sludge. The purpose here is to obtain the composition of the slurry as well as possible in a form suitable for the particular application. It is also an object to provide a method for stopping anaerobic digestion in a slurry as effectively as possible.

To achieve the aforementioned objects, the method according to the invention is characterized by what is mentioned in the characterizing part of the independent claim below.

The present invention relates to a process for the preparation of a cementitious furnace fuel utilization product, which is formed from finely divided loose particles, whereby the coarse digestion sludge 15 is fed simultaneously with the particulate solids and air into a finely divided pulp, The comminuted digestate is effectively contacted with: * · * · air to stop anaerobic reactions in digestate, and •; · ·: The digestion slurry particles are dispersed in 20 solids of inorganic origin or the solids of inorganic origin are dispersed in the digestion slurry particles to form a utility product consisting of loose particles. The invention is characterized in that the refiner is a refiner using a refractory mill and that the inorganic material fed to the refiner is ash, a mixture of sand and ash or fly ash.

• • • • • • • •; ***. The solids content of the lumpy digestate slurry is typically 20-30%.

• * · • · · :: Digestion sludge cans are typically ground in a refiner to a size <1 mm * ':: particles, even powdery, resulting in substantially total: * ·]: total amount of digestion sludge in contact with air to terminate anaerobic !,] *: operations.

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The refiner-based refiner automatically absorbs a sufficient amount of air from the sludge inlet to stop anaerobic functions in the comminuted digestate. If necessary, additional air or oxygen-containing gas can be supplied to the device.

5 An inorganic substance such as sand or fly ash is added to the refiner at the same time as the digestion sludge. This results in a dry-feel material whose particles remain loose and do not lump again. This results in a slurry which is easily handled, for example, for transport, storage or dispensing.

The inorganic material is fed in an amount such that a product of the desired composition is obtained. Inorganic matter, such as sand and ash, can also absorb moisture. The drier the sludge, the less sand, ash or other additives are needed. The destination of the recovered product partially determines how much and what inorganic matter is or can be added to the digestion sludge.

The sand is fed to the digestion slurry typically in a ratio of digestate / sand between 1 / 0.5 and 1/4.

Similarly, the ash can typically be fed in relation to the digestion sludge

• · I

digestate / ash from 1/1 to 1/5.

• · • · ·

The ash can contain even toxic substances and its use may be restricted.

• «* ··· * 20 Sand is clean but relatively expensive, which limits its use. Therefore, sand and ash mixtures can also be used if the most economical solution is available.

., * · * If desired, organic matter or »·«: * bedding such as bark, peat, chips, sticks, straw or other airiness may be added to the slurry; : * · 25 yielding organic solids. Additionally, something can be added to the slurry mixture

• M

: | * *: An additive such as lime or a substance that affects pH.

• • 4 4 * 4 · If desired, the slurry can be treated with two or more reciprocating mill type successively.

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In the past, it has been very difficult to handle either too wet, drier or too fine sludge. Wet sludge is difficult to mix with anything. In the partially dried curdled slurry, anaerobic reactions continue inside the cakes, causes bad odor. On the other hand, a very finely ground slurry is also difficult to handle as such.

By applying the solution according to the invention, the slurry cans can be finely ground and mixed with air so that the anaerobic reactions are definitively terminated.

By mixing sand, ash or the like into the comminuted slurry, various slurry mixtures can be obtained which are suitable for various recovery applications.

10 Sand and ash make the mixture even and easy to handle, making it easy to use.

The device used in the invention is particularly well suited for use when it is necessary to simultaneously feed or mix very different substances 15 such as sludge, sand or ash and air.

The present invention will now be described in more detail with reference to the accompanying drawings, which are exemplary only, in which:. 1a illustrates schematically the apparatus used in the invention for the production of digestate-containing ·· * · ... · 20 utility products; .. * FIG. Ib schematically illustrates another device φ · * · .. * used in the invention for producing a digestate-containing beneficial product; • · • · · * · γ FIG. 2 is a schematic vertical sectional view of the application of * * 25 multi-ring counter-mill mills with five rings ··

* .., · with the device according to FIG. 3 intersection AA of the device

in accordance with; : * · *: FIG. Fig. 3 is a schematic horizontal sectional view of a · ·: | ": multi-ring reciprocating mill apparatus applied in accordance with the invention, in Fig. 30, in accordance with BB; 5 119475 Fig. 4 is a top view of one of the rotors; Fig. 2 is a schematic cross-sectional view of a device according to the invention in which the rotor pair has an open outer periphery, Fig. 6 shows a lumpy digestion slurry obtained from digestion, and Fig. 7 shows a useful product manufactured according to the invention.

Figure 1 schematically illustrates a device 10 for producing a useful product containing digestion sludge. The device 10 is a high-efficiency refiner which is known per se, and which has been previously described e.g. in Finnish patents FI-105699 B and FI-105112 B and PCT publication WO-96/18454.

The apparatus 10 is fed to a dry solids content of 20 to 30% dry solids, typically forming a lumpy mixture. The digestion slurry in the apparatus is ground to a very fine powder which is discharged from the apparatus through the outlet 14. The unit mixes 10 air in the unit 16. The unit will automatically flow to the unit unless the unit is shut down and prevented from entering. Without air, 1S anaerobic reactions in the digestion slurry stop. In addition, the digestion sludge can be mixed with various inorganic materials, such as sand or ash, in the device 18. The slurry mixture leaving the device is suitable for various ... recovery applications. The composition of the mixture is such that the mixture can be easily «· * • · · '. handle and carry. It is no longer sticky or lumpy.

• * • ♦ ·, ·. · '20 In FIG. Ib shows another alternative solution according to the invention for the preparation of a useful product. This solution employs two refractory ^ · • ..: mill-based refiners / mixers. The first device 10 operates * · * ·· · * in FIG. 1a as a refiner for a curdled digestate. The slurry mixture 14 leaving the first device 10 is conducted to the second device. 25 countermeasure device 10 'which can mainly operate • * · *; * ', For example, as a mixer for mixing the powdered digestion slurry with •,;.: Additional inorganic material 18 such as sand or ash, or other additives 18' or * ··· φ * ... * adds digestion slurry as needed.

If desired, the digestion slurry may be run two or more times through the same refiner, as shown by arrow 14 'in Fig. 1b.

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In the figures FIG. 2 and FIG. Figure 3 shows a typical device 10 applied by the invention for fragmenting (milling) the dried, curdled slurry into small particles and dispersing (mixing) in air so that the anaerobic reactions still occurring in the curds of the slurry are stopped. The device is so called. a centrifugal mixer operating on the back mill, 5 or pin mill principle.

FIG. 2 and FIG. The device shown in Fig. 3 has two concentric rotors 20 and 22 extending in opposite directions. One of the rotors could be a stator or could run in the same direction as the first rotor, but at a distinctly different speed. The main thing is that there is a relatively large speed difference between the rotors.

10 The first rotor 20 has blades 26, 26 'and 26' arranged on three circumferences 24,24 'and 24'. Blades 30 and 30 'are similarly disposed on the second opposite rotor 22 in two circumferences 28 and 28'. The rotors may have more or less circles or wings shown in the figures, as the case may be. Preferably, the peripheral blades 26, 26 'and 26' of the first rotor 20 are supported, except for the body portion 32 15 of the rotor 20, below the annular support portions 34 ', as exemplified in Figure 4. The support portion of each circumference is essentially only wing-length in radial direction. Figure 4 shows a part of the rotor 20 at the periphery 24 '.

* * * v · * The digested slurry 12 is fed to the device 10 through its central inlet 36 * "*. The rotor 20 and 22 move in different directions under the influence of the slurry rotors and • · \ V 20 centrifugal force to the outermost periphery of the rotors. * ... · from which the fragmented slurry in the case of Figure 2-3 is tangentially discharged through the outlet 38.

··· • i • · ·· ·

The wings 26,26 ', 26 "have collision surfaces a, a', a" in front of the direction of travel indicated by the arrows of these wings. The wings 30,30 'respectively have the collision surfaces b, b' in the forward direction of these wings: * * *: 25. The digestion slurry fed into the unit first collides. . ·. to the collision surfaces a of the wings 24, which throw the slurry obliquely outwards so that the slurry • f »·· ·. * · *. the collision surfaces b of the wings 30 traveling in the opposite direction, and travel «• i *. obliquely in the other direction outwards. This is how the slurry is affected by the impact surfaces • · i • * ·! throwing the ring through the ring toward the outer periphery of the rotors 40, from which the slurry treated in the apparatus is discharged through the outlet 38.

7 119475 Thus, the sludge and any other material colliding with each of the circuits with high motion energy collide with the collision surfaces of the wings in question. In the opposite directions, rotors rotating at high speeds of 1500 to 3000 rpm, typically about 1600 rpm, in addition to efficient disintegration, provide powerful centrifugal forces that maintain effective flow in the device.

The gap 44 between the outermost periphery 24 "and the housing wall 42 forms an annular or cylindrical trough toward the rotors through which the treated material passing through the peripheries is guided to the housing outlet. The outlet can be tangentially connected, for example, with a motor driven screw 10.

In the case of Figures 2-4, the cross-sectional profile of the wings 26,26 ', 26 ", 30, 30' is rectangular and rotated such that the collision surfaces of the blades are radial. The collision profile of one or more wings may deviate from the radial direction. non-shaped, for example triangular.

The peripheries formed by the impact surfaces are at a small horizontal distance L from each other. This distance can be the same between all adjacent circles, M · #, • t! · * Typically about 2-4 mm. On the other hand, the distance L between the rings may be decreasing _ · *: * ϊ when moving outward from the center of the device, e.g.

• i · • · • · ·· ·

The spacing of the wings a, a ', a "or b, b', distance S, is on the outermost rings 24", 30 'preferably • · · · • * * *. noticeably smaller than the inner ring 24.30. The distance S could be the same.

• a · * IV, The large blade spacing on the innermost blades allows the material to be fed into the device • a * · * 25, which contains relatively large coarse aggregates, agglomerates. A smaller distance S on the outer periphery allows for a good grinding of lumps, agglomerates.

• · • »a ♦ * a ···«, .. ,; A significant advantage is achieved when the number of wings and the distances between the rings, the so-called "wings"

stringency, can be selected according to the particular need. Both the spacing between the rings 8 119475 and the spacing between the blades can be traced to decrease towards the periphery, whereby disintegrating lumps or the like are forced into increasingly tight spaces as they flow towards the periphery, which enhances dissolution.

In FIG. 5 is a modification of FIG. 2-3 of the device shown. FIG. 5 illustrates a device in which the housing walls 42 'are spaced from the outer periphery of the rotors 24 ", leaving a space 48 between the rotors and the housing walls into which the slurry is ejected from the collision surfaces a" of the outer peripheral blades. Part of the slurry may freely fall down into the funnel-shaped bottom 50 of the housing, some will be ejected up to the housing walls 42 and flow downwardly along these walls toward the outlet 52 in the funnel-shaped bottom 10.

A useful product produced by the process according to the invention means a finished product which, without composting, is available as a fuel for a cement kiln. The digestate with added ash is well suited for use as a cement kiln fuel because it still contains considerable amounts of combustible material. Any toxic substances in the ash decompose in a high oven temperature of 1450 ° C. Any remaining toxic substances will not cause any damage to the cement or concrete from which they will not be released. Substances other than ash and sand can be used as an inorganic, mineral, binder in the slurry · # · ♦ · · * · '*. For example, waste gypsum or rock dust or other industrial dust such as 20 from flue gas cleaning can be mixed with sludge.

• * · * · ♦ • ·

In FIG. Fig. 6 is a view of untreated partially dried '1' digestion slurry. In FIG. 7 is a corresponding view of a loose and readily usable utility product of digestion sludge and ash according to the invention having a particle size of less than 1 mm.

• · * · · ♦ · ♦ • *. * * *. The invention is not intended to be limited to the exemplary embodiment of the invention described above, but is intended to be widely applied within the scope of the following claims.

♦ ♦ · · · · · · · · · ··· • · ♦ · · «♦

Claims (5)

119475 Claims, 1. A process for preparing a useful product for finishing a cement kiln of fine loose particles from a lumpy digestate slurry, wherein the lumpy slurry is fed simultaneously with the inorganic solids and air, effective contact with air, 10 to stop anaerobic reactions in the digestion sludge, and - dispersing the digestion sludge particles in a solid of inorganic origin or inorganic solids in a disintegrating agent, and substance is ash, a mixture of sand and ash, or fly ash. Method according to Claim 1, characterized in that the digestion sludge: 20 and the ash are fed in a ratio of "**: digestion sludge / ash in the range 1/1 to 1/5. 3. A process according to claim 1, characterized in that the dry matter content of the curdled digestate slurry is from 20 to 30%. The 25 mills are additionally fed with bark, peat, chips, sticks, straw and / or other volatile organic solids • · · ♦ · · · j *. Method according to claim 1, characterized in that: • · In addition to the refiner, an additive such as lime or other active ingredient at pH ··· is fed. 1. Förfarande för framställning av en nyttoprodukt bestäende av losa partikar ur klumpformat rötslam och avsedd som bränsle för en cementugn, colors det klforforad rötslammet inmatas i en Kvam samtidigt med en fast substans av 5 oorganiskt ursprung och luit , typiskt <1 mm, - det finfördelade rötslammet bringa i effective contact med luft för att avryryta anaerobic reaction reactor rötslammet, och - particle av rötslammet dispersant i fast substance av oorgansikt ursprung eller 10 den fasta substansen av oorganiskurs för att bilda en nyttoprodukt av losa particle, kännetecknat därav, att - man som kvam adverder en Kvam som fungerar enligt repulsionskvamsprincipen, och att - det oorganiska som inmatas i kvamen är Aska, en blandning av sand och 15 Aska eller faska. ··· • · · · · · *. 2. Förfarande enligt patentkravet 1, kännetecknat därav, att rötslam och Aska • ♦. . inmatas sav att förhällandet rötslam / Aska är 1/1 -1/5. • · φ • · · ♦ ·· · ... · 3. Förfarande enligt patentkravet 1, kännetecknat därav, att torrhalten hos det. »· • ♦ • · ··· 20 4. Förfarande enligt patentkravet 1, kännetecknat därav, att man i quamen: V: dessutom inmatar bark, Horn, flis, stickor, halm, och eller face you give organiciskt fast: ***: material som ger luftighet. • · · • · · *;] / 5. Förfarande enligt patentkravet 1, kännetecknat därav, att man i kvamen * · * *; * 'dessutom inmatar et tillaggsämne säsom kalk eller face you give ämne som inverkar 25 päpH. • · • · ♦ • * · • ·