Patent Publication Number: US-7581689-B2

Title: Device for processing excavated material

Description:
This is a continuation-in-part application of international application PCT/EP2004/010032 filed Sep. 8, 2004 and claiming the priority of German application 203 14 137.7 filed Sep. 10, 2003. 

   BACKGROUND OF THE INVENTION 
   The invention relates to a device for processing excavated material including a crushing device disposed above a screening structure. 
   German Utility Model DE 202 14 956 U1 discloses a crushing device with two shafts rotating in opposite directions and provided with crushing discs. The crushing device is suitable for crushing, for example, mineral materials, for example, ground, coarse gravel, stones, or other materials. The materials can be crushed down to particle sizes of 10 mm to 60 mm. 
   Furthermore, DE 101 11 305 A1 discloses an apparatus for processing mineral materials, particularly excavated ground which may include brittle, coarse components. For the crushing, a gapping structure consisting of two shafts is provided, which shafts rotate in opposite directions and which carry pointed bits. The bits are intended to crack the coarse components in order to initiate the crushing. This may occur in the pressure of binding materials such as clay. The coarse components are crushed to a particle size of about 60 mm. The powder or fine particle content is small. 
   The material produced in this way is suitable, as a result of the crushing of the coarse components thereof, basically for re-installation, that is, for example, for the filling of excavated areas such as pits or ditches. However, it is necessary to add to this material filler materials such as cement, ashes, stones powder, fibers, wood chips, saw dust, suspensions such as limestone suspensions, bentonite or other dense suspensions. 
   It is the object of the present invention to provide an improved device for processing excavated materials. 
   SUMMARY OF THE INVENTION 
   In an arrangement for processing excavated materials including a material crushing device and a classifier to which the crushed material is supplied for screening, the classifier includes a leveling structure which provides for a desired orientation of the classifier relative to a horizontal plane independently of the orientation of the crushing device. 
   The material to be processed which includes coarse components is subjected to a crushing process wherein the coarse components are crushed and mixed with the rest of the material. The crushing is preferably accomplished in a very whereby components capable of binding the particulate material are formed. The process is operated in a way such that the components capable of binding the particulate material, which are normally finely crushed parts act as filler materials so that the need for an addition of filler materials such as cement, lime, fibers, wood chips, etc. is eliminated. The fine particle components required for the form-stabilization, drying and/or the solidification of the processed materials are therefore provided by the material being processed itself during the crushing of the coarse material. This material may already be naturally present in the material to be processed in the form of rock pieces (limestone, sandstone or other rocks). But it is also possible to add such coarse materials to materials which do not include the needed components, such as clay-type excavation material, before the processing. 
   However, the coarse material in this case is not an additive in the conventional sense as, by itself, it does not have binding functions. This property is obtained only by the crushing or, respectively milling procedure in the crushing device. The coarse material is fed through the crushing or milling device together with the excavated soil. It has been found that the process can be so controlled that, in spite of the presence of the excavated soil or another corresponding mineral material with clay-like components, a sufficient amount of the fine components can be produced during the crushing of the coarse material. The fine components are then mixed with clay-like components during the crushing procedure and act as added materials. The coarse components provide during crushing for the binding capability particularly well if they are partially pulverized during the crushing. However, the particulate coarse material may also be ground separately. 
   An additive which improves the binding capability such as cement, lime, dusts, seeds or nuts/nut shells can additionally be added to the material being processed preferably before the crushing or grinding but it may also be admixed afterward. The amount of additive required, however, is substantially smaller as it would be without the crushing or grinding of coarse components. The crushed coarse components have particularly the capability of binding water and therefore increase the stability and carrying capability of the processed material if it is used for example for the filling of excavated ditches without provoking an undesirable subsequent hardening of the material. If the carrying capability of the processed material is obtained only by the addition of cement the material becomes too hard so that a later opening of the ditch becomes difficult. With the present invention the need for additional materials can in many cases be lowered to less that 0.5 wt %. With a water content of up to 30% and a rock content of about 50% generally no additional binding materials are needed. 
   If the material to be processed is a binding material, that is if it contains pliable water-containing solid materials such as clay, the rock powder formed during the crushing acts as an additive material. The rock powder may have different binding properties depending on its chemical constitution. It may, for example, be water absorbing. It may furthermore have stabilizing or solidifying effects by ion-exchange processes. It may further have a porrolanic binding effect. It may also have a binding effect by absorption of water, for example, it is contains hydrate components. Furthermore, it may form hydrate binding which may be established by microcrystal growth. This is particularly the case, if a coarse material, concrete or other construction waste materials are used. Generally, such construction waste materials shall include unsaturated components and consequently, have a residual binding capability. Furthermore, after the fine-milling or crushing re-crystallization processes may result in the establishment of renewed solidification. 
   The material may also be so dry that it can be screened. It has been found that larger stones still present after the crushing can be sifted out without essential adherences of clay or the like. 
   Particularly advantageous are crushing devices with asymmetrical discs for the accommodation of tools. 
   In a particularly preferred embodiment according to the invention, the crushing device is in the form of a milling cutter which is disposed above a screening structure such as a roller classifier, a sieve or a separator. The screening structure is provided with a leveling device by which the screening structure can be maintained in a predetermined orientation. If for example, a horizontal orientation is to be maintained and the device for processing the excavated material is moved, the screening structure automatically maintains its horizontal orientation. This is particularly important because the screening occurs with the co-operation of gravity. The leveling device makes it possible to construct the crushing device as a movable unit or as an arrangement of several movable units. 
   The invention will become more readily apparent from the following description of an advantageous embodiment thereof on the basis of the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows schematically a device for processing excavated materials including a crushing device. 
       FIG. 2  shows schematically wherein excavated material and coarse components are separately supplied to a crushing device. 
       FIG. 3  shows in a partial perspective view the crushing device of  FIG. 1  or  2 . 
       FIG. 4  shows a modified arrangement showing schematically leveling arrangement; and, 
       FIG. 5  shows a mixing device with an adjustable secondary crushing structure. 
   

   DESCRIPTION OF THE ADVANTAGEOUS EMBODIMENTS 
     FIG. 1  shows a crushing device  1  which serves as a diminution-, milling- and coarse pieces crushing device. 
   The device comprises for example, two shafts  2 , 3  rotating in opposite directions with crushing tools mounted on the shafts  2 , 3 . The crushing tools may be, for example, in the form as shown in DE 101 11 305 A1 or in DE 202 14 956 U1. Other then shown in these patent documents the crushing tools are however so adjustable that not only a piece size of 60 mm is obtained, but that at least part of the coarse pieces are crushed to a much greater degree. This can be achieved in various ways. In this regard, reference is made to  FIG. 3 .  FIG. 3  shows the shafts  2 ,  3  in a perspective view. They carry axially displaced discs  4 ,  5  which are provided at their circumferences with recesses in which break-up chisels  6 ,  7  are supported. The recesses may have the same or different shapes. The break-up chisels  6 ,  7  preferably have conical tips which move toward each other above a plane defined by the axes of the two shafts  2 ,  3 . The respective opposite directions of rotation of the two shafts  2 , 3  are indicated in  FIG. 3  by arrows. Stones engaged between the tips of the break-up chisels  6 ,  7  are broken by the movement of the chisels toward each other by the slowly rotating shafts (for example about 10 to 60 rpm). Interfering materials possibly present such as wood, steel cans, tires are either processed or they are rejected. 
   Otherwise, toothed discs  8  to  14  are disposed on the shafts  2 ,  3  adjacent one another in axially spaced relationship. They may all have the same shape or they may be differently shaped. The teeth  15 ,  16  have radially extending front faces  17 ,  18  and receding back areas  19 ,  20 . The toothed discs  8  to  14  are arranged on the shafts  2 , 3  so as to provide spaces there between into which the toothed discs of the opposite shaft extend. The number of toothed discs  8 - 14  is preferably larger than the number of discs provided with chisels (discs  4 ,  5 ). 
   The teeth of the discs are so arranged that it is disposed opposite on essentially cylindrical pressure surface portion between circumferentially adjacent teeth of the disc of the opposite shaft forming a pressure gap for the crushing of the coarse material components. But the toothed discs  8  to  14  of the two shafts may also be arranged closely adjacent one another and have a diameter such that the enveloping circles of the toothed discs  8  to  14  of the two shafts  2 ,  3  do not intersect. Rather they are so selected that between the tooth backs of the booth discs of the two shafts  2 ,  3  remains a small gap which serves as a compression gap. 
   The crushing device of  FIG. 1  also includes a drive arrangement for the two shafts  2 ,  3  comprising for example two hydraulic motors, one for each shaft  2 ,  3 . both hydraulic motors may be powered by a common diesel engine. Above the coupling device  1  there is furthermore a transport device  21  which transports a material mixture  22  to the crushing device  1  as shown schematically in  FIG. 1 . The material mixture  22  is for example excavated soil of clay-like constitution. It contains coarse components in the form of stones  23 ,  24 . They may be contained naturally in the material mixture  22  or they may be added as needed. The stones  23 ,  24  may be bricks, concrete blocks, natural stones (limestone, sandstone, granite, basalt, gneiss, tuff, parphyry or similar). Also a mixture of different stones, gravel, sand or similar materials may be used. The material mixture  22  is fed by the transport device  21  to the crushing device  1  where it may be collected in a collection funnel  25  disposed above the crushing device  1 . 
   During operation of the crushing device  1 , the crushing tools carried by the two shafts  2 ,  3  engage the clay-cohesive material and moves it downwardly. Furthermore the stones  23 ,  24  split and broken up by the break-up bits or chisels  6 ,  7  ( FIG. 3 ). Then the broken pieces are further crushed by the toothed discs  8  to  14 , wherein the process is so controlled that a high proportion of small particles is generated. The crushing procedure results partially in the milling of the stones to fine powder. The stone powder formed hereby (quartz powder, lime powder, etc.) is instantly mixed with the clay like material of the material mixture  22 . If the clay like material sticks to the toothed discs  8  to  14 , it is carried once around and subjected to an even more intense mixture with the stone powder. In this way, a largely homogenized solubilized material  26  is formed consisting of ground stones, particulate components and clay-like base material. This material mixture is generally suitable for immediate re-installation at the construction site (highway construction). 
   The stone powder content generated during the crushing procedure results at least in an absorption of moisture and therefore in an instant reduction of the stickiness and the kneadability of the material. Over a larger period this stone powders tend to harden also if they are formed in the crushing procedure described above in a moist environment. The hardening or solidification process may be based on ion exchange processes, the formation of pozzolanic bindings or hydration processes. The material is suitable to a low-pore compression and in this way becomes capably of carrying high loads. The binding components of the mixture ensure that, upon re-excavation of ditches or the excavation of new ditches adjacent to filled in ditches the walls of the ditches are very stable. 
   The crushing device  1  as shown in  FIG. 2  is particularly suitable for the processing of material  27  of clay-like base structure without coarse material components. The needed coarse material that is stones  22 ,  23  can be supplied by an additional transport device  28  to the crushing device which is formed by the two shafts  2 ,  3  with the break-up discs  4 ,  5  and the toothed discs  8 - 14 . In this way, the supply of the material  27  and of the stones  22 ,  23  can be accurately controlled. The stones  22 ,  23  are generally construction waste materials that is concrete pieces, brick-waste or other demolition material, but they may also be natural stones. 
   The stones  22 ,  23  are crushed in the crushing device in the presence of the material  27  whereby the stone powder generated is homogenously mixed with the material  27 . The material mixture  26  formed in this way is suitable for installation at the construction site. 
   The processing arrangement as illustrated in  FIG. 4  comprises the crushing device  1  as shown in  FIG. 1  and described earlier in connection with  FIG. 1  which is supplemented by a supplemental treatment arrangement  31 . The supplemental treatment arrangement  31  comprises a transport device  32  with two conveyors  33 ,  34  which supply the material  26  that has been homogenized in the crushing device  1  to a roller classifier  35 . Above one of the conveyers  33 ,  34  a dosing apparatus  36  is arranged by way of which additive materials such as cement are supplied to the homogenized construction materials on the conveyers  33 ,  34 . The dosing apparatus comprises for example a storage container  37  and a cell wheel sluice  38  disposed at the outlet of the container  37 . Between the conveyor  34  and the roller classifier  35 , a transport wheel or a supplemental milling device  39  may be arranged which takes up the material supplied by the conveyor  34  and distributes it on the roller classifier  35 . The roller classifier comprises a group of round or oval rollers which rotate in the same or opposite sense and between which the material  26  supplied to the classifier  35  passes downwardly and is collected on a pile  41 . Coarse components such as insufficiently crushed stones  42  are discharged from the roller classifier  35  to one side and may be taken for further processing. 
   The closing apparatus  36  is preferably so adjusted that it supplies only relatively small amounts of additional materials that is amounts of less than 0.5 wt % of the materials transported by the conveyor  33 ,  34 . Also a control device may be provided which determines this dose depending on the residual moisture in the material  26 . A corresponding moisture measuring device may be provided, however is not shown in  FIG. 4 . For the processing of sludge, however, the dosage of additional material may be increased above the normal value. 
     FIG. 4  shows schematically a transport wheel  39  which preferably forms a mixing device with an additional supplemental crushing function as shown in greater detail in  FIG. 5 . It includes a motor  43  preferably with a horizontal axis of rotation which is driven by a hydraulic motor or any other drive means. The motor  43  preferably extends over the full width of the conveyor  34  shown in  FIG. 4 . At its circumference it is provided with tools such as bits or chisels  44 ,  45 ,  46 ,  47 , which are inclined in the direction of rotation. Preferably chisel bits with rounded heads are used. However, other bits such as flat tip bits or suitable hammer bits may be used. Preferably the bits  44  to  47  are rigidly mounted. However, particularly with the use of hammer bits they may be supported so as to be pivotable about a pivot axis which extends parallel to the axis of rotation of the motor  43 . The motor  43  in most cases is designed for a rotational speed of 200 to 1000 rpm. Preferably its speed is 400 rpm. 
   The motor  43  is covered by a hood  48  which is arranged above the motor  43  at the side thereof opposite the conveyor  34 . Preferably, the hood  48  covers the motor  43  over about a quarter of its circumference. It is pivotally supported on a support hood  49  which is mounted so as to be pivotable about an axis  50 . A hydraulic cylinder  50 ′ is connected to the support hood  49  for opening an closing the support hood  49 . The motor  43  may be supported by the conveyor  34  or by a frame which carries both the motor  43  and the conveyor  34 . The hood  48  is supported by the support hood  49  by a bearing structure  51 . This pivot axis is disposed above the motor  43 . The pivot position of the hood  48  is determined by an adjustment mechanism in  52 , for example, in the form of a simple adjustment bolt or in the form of fluid, that is hydraulic or pneumatic cylinders. 
   The hood  48  is curved so as to extend about parallel to the circle of movement of the bits  44 ,  45 ,  46 ,  47 . It delimits therefore with the motor  43  a gap-shaped crushing space  53 . If necessary one or two impact webs  54 ,  55  may be provided on the hood  48  which extends over the full length of the motor  43  and project toward the motor  43 . 
   The mixing device  39  provides for further mixing and crushing of the material supplied by the conveyor  34 . The particle size can be adjusted by the adjustment mechanism  52  as desired. As a result a highly homogenous material is supplied to the roller classifier  35 . 
   In accordance with the invention, for the processing of excavation materials or of other materials which may be provided for re-installation at a construction site or another type of processing or for waste management, a crushing process is provided wherein excavated materials and additionally coarse pieces are moved through the crushing, milling and jamming material removal arrangement. The stone powder formed during crushing of the coarse material by suitable crushing an/or compression procedures is used as locally produced additive material for mixture with the excavated soil. This additive material is suitable for controlling the moisture of the excavated soils or sludge as well as stabilizing and solidifying the excavated material so that it becomes stable. Also granulated formation is possible. The degree of drying and solidification can be adjusted by the degree of crushing or milling for example by a more or less intense milling of the coarse material components depending on the moisture content or the desired subsequent solidification. Furthermore, coarse components such as asphalt, construction waste, concrete pieces or natural stones may be added to the excavated material so as to obtain during the crushing procedure the desired stone powder amount. The crushing-milling and jamming material removal arrangement breaks down any destructible jamming material and prevents the passage of coarse jamming materials which can not be crushed. Those material parts are rejected. For example, large steel parts are not engaged by the crushing wheels or they result in a blockage and reversal of the machine. Overloading of one or multiple reversals result in a shut-down of the device. 
   The plant as shown in  FIG. 4  which includes a separation device  35  in the form of roller classifier or another material separation apparatus, is provided with a leveling arrangement  60 . This arrangement comprises electrical or hydraulic actuators  61 ,  62  which support the classifier structure  63 . The actuators  61 ,  62  are preferably so connected to the classifier structure that they can adjust the inclination of the classifier in the longitudinal direction as well as in the transverse direction. The actuators  61 ,  62  are supported at their other ends, for example, on a machine frame which also supports the conveyor  34 , and the mixing or milling device  39  but which is not shown. A control unit  64  is connected to the actuators  61 ,  62  for operating the actuators appropriately. To this end the control unit  64  senses the inclination of the classifier frame  63 . In addition the control unit is connected to input means by which an operator can enter a desired inclination of the frame  63 . If for example, an inclination of 5 degrees with respect to the horizontal is desired this value is entered by the operator. The control unit then causes the adjustment of the actuators  61 ,  62  such that this inclination is maintained also if the whole plant changes its position that is also when the support points  65 ,  66  for the actuators  61 ,  62  are displaced by movement of the plant. The leveling arrangement  60  ensures that the classifier  35  can properly perform also under difficult operating conditions as they frequently occur in the practical operation at construction sites. 
   Driving the material processing furthermore ahead of or subsequent to, the main crushing procedure, a preliminary or, respectively, follow-up crushing may be provided for and liquid such as water or an aqueous solution may be added to the material between the individual crushing stages. Water may be added for example to enhance the binding of the added material or the powder material formed during crushing. The absorption of liquid by the addition of powdered dry material or the moistening of the material by addition of water is controlled on the basis of the initial moisture content of the material. 
   In accordance with the invention, the classifier is for example a roller classifier connected to a leveling structure which ensures a desired orientation of the classifier independently of a movement or the set-up of the whole arrangement. The desired orientation may be horizontal or inclined. By ensuring the desired orientation the classifier reliably can fulfill the classification task to be performed by it. As a result the classifier can be used in connection with pivotable or movable processing plants wherein, after a position change no manual adjustment of the classifier is necessary as it is automatically maintained at the desired inclination entered by the operator.