Patent Application
20070272776
The invention relates to a method for processing excavated material, such as mud, waste material, or other types of material containing interfering substances, as well as an apparatus for realizing this method.
German Utility Patent 202 14 956 discloses a comminuting apparatus with two counter-rotating shafts on which crusher plates are mounted. The comminuting apparatus is suitable, for example, for crushing mineral materials such as excavated earth, coarse gravel, rocks or other types of material. A fine-grain comminuting is possible, wherein grain sizes of 10 mm to 60 mm can be achieved.
Furthermore known from German Patent 101 11 305 A1 is an apparatus for processing mineral material, in particular excavated earth, which can also contain coarse-grained, brittle components. A splitting tool is used for the comminuting operation, which comprises two counter-rotating shafts with tapered chisels positioned thereon. These chisels are designed to break up the coarse components for a comminuting, wherein this can occur in the presence of cohesive material, such as clay-containing or loam-containing material. The coarse components are comminuted to a grain size of approximately 60 mm, wherein the share of powdery and fine-grained material is low.
As a result of the comminuting of the coarse components, the material generated in this way is basically suitable for reuse, e.g. for filling in excavated areas in the ground, such as ditches or pits. However, an additive such as cement, ash, powdered rock, granulate, fibers, wood shavings, wood flour, and suspensions such as lime suspensions, bentonites, or dense suspensions must be added to this material.
Starting with this premise, it is the object of the present invention to specify an improved processing method.
This object is solved with the method as defined in claim 1:
The material of an indeterminate shape which is to be processed is subjected to a comminuting process, for example if coarse material pieces are present, in which the coarse material is at least partially comminuted and mixed with the material to be processed. The comminuting operation in that case is selected such that bondable components are released during the comminuting of the coarse material pieces. The process is realized such that the generated bondable components, in general extremely fine components, act in the manner of an additive. The processing consequently can take place without having to mix in additional materials such as cement, lime, fibers, shavings, and the like. The fine components necessary for the form stabilization, drying, and/or hardening of the processed material are generated from the material to be processed itself during the comminuting of the coarse material pieces. This can be present naturally in the material to be processed in the form of chunks of rock (limestone, sand stone or other types of stone), or the coarse components can also be added just prior to realizing the processing method according to the invention to the loam/clay excavation material which does not contain such coarse material. The coarse material can furthermore also be added during the comminuting process. However, the coarse material does not represent an additive in the traditional sense because it is not bondable when used by itself and obtains this characteristic only through the comminuting and/or grinding operation in the comminuting apparatus. The coarse material travels together with the excavated earth through the comminuting apparatus. It has turned out that the process control can be selected such that a sufficiently high share of the fine material can be generated from the coarse material, despite the presence of the excavated earth or a different, corresponding mineral material with loam/clay components. This share of fine components is mixed during the comminuting operation into the clay/loam component and acts as an additive. The bonding capacity of the coarse component results from the comminuting process, in particular if the material is at least partially pulverized. However, the grinding of the coarse material can also be done separately.
A bondable additive can furthermore be added to the material to be processed (e.g. cement, lime, dusts, seeds, nuts/nut shells) preferably before or after the grinding. In that case, the amount added is considerably lower than would be required for a process without grinding of the coarse components. The ground coarse components above all are capable of absorbing water and thus increase the stability and soil-bearing capacity if the processed material is used, for example, for filling in excavated ditches, without resulting in an unacceptable post-hardening of the material. If the soil-bearing capacity of the material to be processed is achieved only by adding cement, the material will harden so strongly that a re-excavation of the ditch at a later date becomes difficult. The invention in many cases allows lowering the required amount of additive to below 0.5 weight %, wherein the admixture of an additive frequently is not even necessary. As a rule, no additional bonding agent is needed for a water content of up to 30% and a rock share of approximately 50%.
If the material to be processed is a cohesive material, meaning it contains plastic, water-containing solids such as clay or loam, then the powdered rock obtained during the comminuting operation, for example, acts in the manner of an additive. Depending on its chemical composition, the bonding properties of the powdered rock can vary, for example it can be water-absorbing. In addition, it can also have a hardening effect as a result of ion-exchanging processes or it can have a puzzolanic bonding effect. The material can furthermore have a bonding effect by absorbing water, for example if it contains anhydride components. In addition, it can form hydrate bonds as a result of micro-crystal growth. This is the case in particular if bentonite or other construction waste materials are used as coarse material. Construction waste materials of this type generally contain non-bonded components and thus have a residual bonding capacity. In addition, re-crystallization processes can furthermore lead to renewed setting after the fine grinding.
The dryness of the material can furthermore be selected such that the material can be sifted. It has turned out that rocks which may still be present can be sifted out without noticeable amounts of loam or the like adhering to them.
Comminuting apparatuses with asymmetric plates for accommodating tools are considered particularly advantageous.
Further details of advantageous embodiments of the invention can be found in the drawing, the associated description, or the dependent claims, which show in:
Otherwise, the shafts 2, 3 are tightly covered with uniformly embodied toothed disks 8 to 14, wherein differently embodied toothed disks can also be used. The teeth 15, 16 are provided with approximately radially oriented frontal areas 17, 18 in rotational direction and with back areas 19, 20 which are slanted counter to the peripheral direction. The toothed disks 8 to 14 are respectively arranged with gap, meaning adjacent toothed disks arranged on the shaft 2 respectively enclose a gap. The toothed disks on the shaft 3, which are also arranged so as to enclose a gap, respectively engage in the gaps. The number of toothed disks 8 to 14 is preferably higher than the number of plates carrying the chisels (plates 4, 5).
A mostly cylindrical pressure surface is assigned to each toothed disk on the respectively opposite side, wherein this pressure surface together with the tooth back 18, 19 of the respectively opposite-arranged toothed disk acts as a pressure gap for grinding the coarse material. However, it is also possible to arrange the toothed disks 8 to 14 on the two shafts so as to respectively fit against each other. In that case, the peripheral circles of the toothed disks 8 to 14 on the two shafts 2, 3 do not overlap. Rather, the distance is adjusted such that respectively only a small gap remains between the tooth backs of the toothed disks on both shafts 2, 3 which then functions as crushing gap.
The comminuting apparatus 1 according to
During the operation of the comminuting apparatus 1, the comminuting tools supported by the shafts 2, 3 pick up the loamy, cohesive material and convey it in downward direction. The rock-type material 23, 24 is furthermore split and broken up by the chisels 6, 7 (
The comminuting apparatus 1 according to
The system illustrated in
The metering device 36 is preferably adjusted such that only small amounts of material are released, amounting to less than 0.5 weight % of the material amounts conveyed by the conveyor belts 33, 34. Also provided can be a control device which determines the metered-in amount in dependence on the residual moisture of the material 26. A respective moisture-sensing device can also be provided, but is not shown in further detail in
The mixing device 39 with post-comminuting function, which is indicated only schematically in
The rotor 43 is assigned a cap 48 which is arranged above the rotor 43, on the side opposite the conveyor belt 34. The cap preferably covers approximately one fourth of the peripheral area of the rotor 43 and is supported on a covering hood 49 that is arranged above the rotor 43, such that it can pivot around a pivoting axis 50. A hydraulic cylinder opens and closes the covering hood 49. The rotor is fixedly connected to the conveying belt 34, for example, or to a frame which also carries the rotor 43 and the conveyor belt 34. The cap 48 is positioned pivoting by means of a corresponding bearing arrangement 51 on the supporting covering hood 49, wherein the pivoting axis is arranged above the rotor 43. The pivoting position is secured, for example, by an adjustment mechanism 52 in the form of a simple adjustment screw or also in the form of fluid-operated cylinders (hydraulic, pneumatic).
The cap 48 is curved approximately parallel to the circular trajectory traversed by the chisels 44, 45, 46, 47. Thus, it delimits together with the rotor 43 a gap-type comminuting space 53, wherein one, two or more beater bars 54, 55 can be attached to the cap 48, if necessary. These beater bars extend over the complete axial length of the rotor 43 and project in the direction of rotor 43.
During the operation, the mixing device 39 effects a further mixing and comminuting of the material supplied by the conveyor belt 34. The adjustment mechanism 52 can be used to select the desired grain size. A mostly homogeneous material is thus deposited on the roller classifying screen 35.
According to the invention, a grinding operation is used for processing excavated earth or ground, or any other type of material of an indeterminate shape, which is to be reused at a construction site, for example, or which is to be processed further or is destined for waste disposal. During this grinding operation, the respective excavated earth travels along with the coarse-material pieces through the machinery for comminuting, grinding, and removal of undesirable material. The powdered rock, obtained during the comminuting of the coarse material by means of suitable breakage and/or crushing operations, can be used as additive for the excavated earth which is generated, so-to-speak, on location. This additive is suitable for regulating the moisture content of the excavated earth or mud, as well as to effect a stabilization and hardening of same. The material becomes compact. Also possible is a granulation. The degree of drying and compacting can be adjusted through the grinding fineness, for example by grinding the coarse components to a more or less fine degree, depending on the amount of moisture or the desired degree of post-compacting. In addition, coarse components such as asphalt, construction waste materials, concrete chunks, or natural stones can be added during the comminuting operation to the excavated earth to generate the desired amount of powdered rock. The machinery for comminuting, grinding, and removing undesirable material is designed to comminute all materials which can be comminuted and prevents the passage of undesirable materials which cannot be comminuted. These materials are rejected, e.g. large steel pieces are not picked up, because they will otherwise result in blocking or reversing the machine. Any overload or one-time or multiple reversing can result in a shut-down of the machinery.
During the material processing, it is furthermore possible to add fluid, e.g. water or a watery solution, to the material during the comminuting operation as well as between the individual stages of a multi-stage comminuting operation, either before or after the comminuting. Water can be added to the mixed-in or generated fine-grain components, for example, so as to result in the setting or aid in the setting of the material. The absorption of liquid by adding pulverized dry material or the moistening of the material by adding water takes place in dependence on the starting moisture content of the material.
| Number | Date | Country | Kind |
|---|---|---|---|
| 103218327 | May 2003 | DE | national |
| 103375902 | Aug 2003 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/05146 | 5/13/2004 | WO | 12/4/2006 |
