METHOD AND DEVICE FOR BULK SORTING MACHINES

Abstract

Bulk sorting using a bulk sorting machine that comprises a conveying means (7), an exciter (5) for generating a separating force, a splitter (1) with a blade, and a sensor (2) that senses the particles hitting the blade. The signal generated by the sensor (2) is used to optimize the result of the separation process.

Claims

30. A method for sorting a bulk-material stream having at least a first bulk-material fraction and a second bulk-material fraction, wherein the bulk-material stream is directed toward a splitter to be positioned between the bulk-material fractions and having a separating edge, wherein the bulk-material fractions only partially overlap or do not overlap on or slightly above the separating edge, wherein with at least one sensor the number stream is detected of the particles that pass through a detection region of the at least one sensor, the detected number stream being assigned to the corresponding position of the at least one sensor, wherein a control signal is generated from the measured number stream and from the corresponding position of the at least one sensor, and wherein the separating edge and the bulk-material stream are aligned relative to one another on the basis of the control signal in such a manner that the first bulk-material fraction comes to be situated substantially on the one side and the second bulk-material fraction comes to be situated substantially on the other side of the splitter.

31. The method as claimed in claim 30, wherein at least one of the detection region of the at least one sensor extends substantially parallel to the separating edge and the detection region is situated above the separating edge.

32. The method as claimed in claim 30, wherein the separating edge is directed contrary to the bulk-material stream.

33. The method as claimed in claim 30, wherein the detection region is defined by a plane that extends substantially parallel to the separating edge or at least one of the detection region is defined by a cuboid situated on or above the separating edge, the longitudinal axis of which extends parallel to the separating edge, and wherein the detection region does not extend over the entire width of the bulk-material streams.

34. The method as claimed in claim 33, wherein at least one of the plane extends on or above the separating edge and said longitudinal axis of the cuboid coincides with the separating edge or the underside of the cuboid rests on the separating edge.

35. The method as claimed in claim 30, wherein the separating edge is positioned by means of the control signal substantially where the number stream of the particles determined by means of the at least one sensor is minimal.

36. The method as claimed in claim 30, wherein the at least one sensor exclusively detects the particles impinging in the region of the separating edge but not the particles impinging outside said region.

37. The method as claimed in claim 30, wherein the distribution function of the number stream of the particles above the corresponding positions of the at least one sensor is determined, and wherein a relative minimum of the distribution function or a relative minimum of a derivative of the distribution function is determined, and wherein the separating edge is positioned relative to the stream of bulk material in the vicinity of this minimum.

38. The method as claimed in claim 37, wherein the distribution function of the number stream of the particles at least one of above the separating edge and laterally in relation to the separating edge is determined.

39. The method as claimed in claim 37, wherein at least one of the position of the at least one sensor relative to at least one of the bulk-material stream and to the separating edge is varied in the detection region during operation for the purpose of determining the distribution function of the number stream, and several sensors make available several parallel measurement sections.

40. The method as claimed in claim 30, wherein in a step of separation the bulk material is divided up into the two bulk-material fractions having respectively differing flight trajectories, said step of separation occurring spatially and temporally prior to the impinging of the bulk-material fractions on the separating edge.

41. The method as claimed in claim 40, wherein the separation is controlled with said control signal.

42. The method as claimed in claim 40, wherein the separation is undertaken in a bulk-material separator having a conveying means and an exciter for making a separating force available, wherein at least one of the speed of the conveying means and the force made available by the exciter and acting on the bulk material is/are controlled by said control signal.

43. The method as claimed in claim 42, wherein in a step of setting the separating edge the separating edge is positioned, with separating force suppressed, at the spacing from the active position of the exciter of the separating force at which the signal detected by the sensor reaches a predetermined value.

44. A sorting device for sorting a bulk-material stream having at least a first bulk-material fraction and a second bulk-material fraction, wherein the sorting device includes a splitter, to be positioned between the bulk-material fractions, having a separating edge directed contrary to the stream of bulk material and wherein the sorting device further includes at least one sensor, wherein the bulk-material fractions only partially overlap or do not overlap on or slightly above the separating edge, wherein the stream of bulk material can be guided to the separating edge, wherein the at least one sensor is designed for determining the number stream of the particles that pass through the detection region of the at least one sensor, wherein the detected number stream is assigned to the corresponding position of the at least one sensor, wherein a control signal is generated from the determined number stream and the corresponding position of the at least one sensor, and wherein the separating edge and the bulk-material stream are aligned relative to one another on the basis of the control signal in such a manner that the first bulk-material fraction comes to be situated substantially on the one side and the second bulk-material fraction comes to be situated substantially on the other side of the splitter.

45. The sorting device as claimed in claim 44, wherein the at least one sensor has been arranged in such a manner that it exclusively detects the particles impinging in the detection region.

46. The sorting device as claimed in claim 45, wherein at least one of the separating edge can be positioned in relation to the bulk-material stream at the point at which the number stream of the particles detected by the sensor is minimal and the bulk-material stream can be positioned in relation to the separating edge at the point at which the number stream of the particles detected by the sensor is minimal.

47. The sorting device as claimed in claim 44, wherein the distribution function of the number stream of the particles over the separating edge and laterally in relation to the separating edge can be determined, and wherein a relative minimum of the distribution function or a relative minimum of a derivative of the distribution function can be calculated, in which case said control signal can be made available on the basis of the relative minimum.

48. The sorting device as claimed in claim 44, wherein for the purpose of determining the distribution function of the number stream the position of the at least one sensor relative to at least one of the bulk-material stream and the separating edge is varied parallel to the separating edge during operation, or wherein several sensors make available several measuring sections parallel to the separating edge.

49. The sorting device as claimed in claim 44, wherein the at least one sensor is arranged fixedly in relation to the separating edge or integrated into the separating edge, said at least one sensor and said separating edge being traversable together for the purpose of detecting the particles at various positions; or wherein the at least one sensor is traversable to various positions for the purpose of detecting the particles independently of the separating edge.

50. The sorting device as claimed in claim 44, wherein the at least one sensor is at least one of an optical sensor and a pressure-sensitive sensor and an acoustic sensor.

51. The sorting device as claimed in claim 44, wherein the separating edge has been designed with a positioning device with which the separating edge can be positioned relative to the bulk-material stream on the basis of the control signal.

52. The sorting device as claimed in claim 44, wherein the sorting device comprises product outlets via which the sorted bulk-material fractions can be emitted from the sorting device, further sensors for detecting the particles capable of being emitted via the product outlets being arranged in the region of the product outlets.

53. The sorting device as claimed in claim 44, wherein the at least one sensor can be moved relative to the separating edge independently of the separating edge, or wherein the at least one sensor can be moved jointly with the separating edge.

54. The sorting device as claimed in claim 41, the sorting device being for implementing a method for sorting a bulk-material stream having at least a first bulk-material fraction and a second bulk-material fraction, wherein the bulk-material stream is directed toward a splitter to be positioned between the bulk-material fractions and having a separating edge, wherein the bulk-material fractions only partially overlap or do not overlap on or slightly above the separating edge, wherein with at least one sensor the number stream is detected of the particles that pass through a detection region of the at least one sensor, the detected number stream being assigned to the corresponding position of the at least one sensor, wherein a control signal is generated from the measured number stream and from the corresponding position of the at least one sensor, and wherein the separating edge and the bulk-material stream are aligned relative to one another on the basis of the control signal in such a manner that the first bulk-material fraction comes to be situated substantially on the one side and the second bulk-material fraction comes to be situated substantially on the other side of the splitter.

55. The sorting device as claimed in claim 54, wherein the optical sensor is a light barrier.

56. A bulk-material sorting plant comprising a sorting device as claimed in claim 41 and a bulk-material separator with which the bulk material can be split into the bulk-material fractions in such a manner that the bulk-material fractions only partially overlap or do not overlap.

57. The bulk-material sorting plant as claimed in claim 56, wherein the bulk-material separator is an eddy-current separator or a magnetic separator or an electrostatic separator or a sensor-type sorter.

58. The bulk-material sorting plant as claimed in claim 56, wherein the bulk-material sorter further includes a conveying means with which bulk material to be separated can be fed to the bulk-material separator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Preferred embodiments of the invention will be described in the following on the basis of the drawings, which serve merely for elucidation and are not to be construed as restrictive. Shown in the drawings are:

[0086] FIG. 1 an embodiment of a bulk-material sorting plant with a sorting device and with a bulk-material separator;

[0087] FIG. 2 a schematic representation of FIG. 1, with particles having differing flight trajectories;

[0088] FIG. 3 a schematic representation of FIGS. 1 and 2 with the distribution of the particles;

[0089] FIG. 4 a schematic representation of FIGS. 1 and 2 with the distribution of the particles;

[0090] FIGS. 5a,b,c schematic representations of sensors in the region of the separating edge, which can be employed in a bulk-material sorting plant according to one of the preceding figures; and

[0091] FIGS. 6-8 bulk-material sorters known from the prior art.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0092] Preferred embodiments of the present invention will now be elucidated on the basis of FIGS. 1 to 5.

[0093] In FIGS. 1 to 4 a bulk-material sorting plant 12 is represented schematically. The bulk-material sorting plant comprises a sorting device 13 and a bulk-material separator 14. With the bulk-material separator 14 it is possible for a bulk-material stream S to be split into a first bulk-material fraction S1 and a second bulk-material fraction S2. The two bulk-material fractions S1 and S2 then impinge on the sorting device 13 and are sorted apart there.

[0094] The first bulk-material fraction S1 comprises particles 11, and the second bulk-material fraction S2 comprises particles 10. In the sorting device 13, particles 11 are to be sorted from particles 10. For this purpose the sorting device 13 includes a splitter 1 with a separating edge which is to be positioned between the two bulk-material fractions S1, S2 so that particles 11 come to be situated on the one side and particles 10 come to be situated on the other side of the separating edge. The sorting device 13 further includes a sensor 2 with which the particles 10, 11 of the two bulk-material fractions S1, S2 appearing in the region of the separating edge can be detected. The separating edge extends substantially in the horizontal plane.

[0095] The bulk-material separator 14 may be an eddy-current separator according to FIG. 6. But the bulk-material separator 14 may also have been designed differently, for example as a magnetic separator (FIG. 7) or as an electrostatic separator (FIG. 8). In principle, bulk-material separators of such a type, with which a bulk-material stream S can be divided up into two or more bulk-material fractions, are known from the prior art. The bulk-material separator 14 comprises a material feed 7 and an exciter 5 for the separating force with which the stream of bulk material can be separated.

[0096] According to the method according to the invention for sorting a bulk-material stream S having at least the first bulk-material fraction S1 and the second bulk-material fraction S2, the bulk-material stream S is directed onto the separating edge to be positioned between the bulk-material fractions S1, S2 and onto the at least one sensor 2. The bulk-material fractions S1, S2 do not overlap or overlap only partially in the region of the separating edge—that is to say, on or slightly above the separating edge. “Slightly above the separating edge” means, for example, within a range of at most 50 centimeters, in particular at most 10 centimeters, vertically above the cutting edge. The at least one sensor 2 detects the number stream of the particles that pass through a detection region of the at least one sensor. On the basis of a linkage of the sensor position with the number stream detected at this point, a control signal is made available. The separating edge and the bulk-material stream S are aligned relative to one another on the basis of the control signal, specifically in such a manner that the first bulk-material fraction S1 comes to be situated substantially on the one side and the second bulk-material fraction S2 comes to be situated substantially on the other side to that of the splitter 1. By this means, the bulk-material fractions are easily split apart.

[0097] By a “number stream”, the number of particles impinging over a predetermined unit of time is understood. For example, the unit of time may be a minute or a second.

[0098] With respect to the relative positioning arrangements, in particular the following configurations are conceivable: [0099] The flight trajectories of the bulk-material fractions are influenced by the bulk-material separator in such a manner that the bulk-material fractions impinge on the corresponding side of the separating edge. For example, with the control signal the speed of the material feed 7 or, to be more exact, of the conveying means 7 is influenced and/or the power of the exciter 5 is influenced. [0100] The position of the separating edge is displaced relative to the stream of bulk material on the basis of the control signal. [0101] The position of the separating edge and the flight trajectories are influenced on the basis of the control signal.

[0102] The relative alignment between separating edge and bulk-material stream S is preferentially undertaken in such a manner that the number stream of the particles in the region of the separating edge is minimal. The separating edge is accordingly positioned at the minimum, whereas the sensor may be somewhere else entirely. The sensor is imperatively located at the minimum only when it has been fixedly mounted on the separating edge.

[0103] According to a preferred embodiment of the method according to the invention, the particles impinging in the region of the separating edge are detected by means of the sensor 2. The number of particles impacting per unit of time is designated as the counting-rate or number stream (for example, in number/min=#/min). The current counting-rate determined in this way is compared with the counting-rate at another position in the particle stream S and is used for positioning the separating edge and/or for influencing the flight trajectories of the particles. As a rule, the positioning of the separating edges is performed in such a way that the current counting-rate is at a relative minimum in comparison with the counting-rates after a slight displacement of the separating edge to the right or to the left.

[0104] As sketched in FIG. 3, the plotting of the counting-rate against the spacing x yields a bimodal number-distribution function q.sub.0(x). The left “bump” therein represents the non-conductive material (11), and the right “bump” the conductive material (10). An ideal positioning of the separating edge lies within the region of the minimum of the number-distribution function q.sub.0(x). Depending upon whether a good concentrate quality or a high yield of conductive particles is being striven for, the edge of the separating edge is positioned somewhat to the right or to the left of this relative minimum. On the basis of this insight, the optimal positioning of the separating edge for a separation of conductive and non-conductive material can accordingly be undertaken solely by identification of the minimum of the counting-rate—an additional determination of the metal contents is not necessary. In contrast to WO 2012/118373 A1, the number of particles in one product or in both products of the separation is accordingly not determined directly or indirectly by measurement of representative partial streams, but rather the locally—preferentially horizontally—resolved particle-stream distribution is determined. In contrast to WO 2012/118373 A1, the detection region preferentially does not extend over the entire width of the bulk-material streams S1 and S2 but extends only to the regions of the streams of bulk material that are adjacent (the right flank of S1 and the left flank of S1)—that is to say, to the region between the two “bumps”, and in particular to the regions in which the bulk-material streams S1 and S2 overlap.

[0105] In a preferred embodiment of the invention, in contrast to WO 2012/118373 A1 the number stream is measured of particles that cannot be incontestably assigned to one of the products because they are impacting precisely on the separating edge.

[0106] In a preferred embodiment, as shown in FIG. 1, the sensor 2 has been connected via a data-processing unit 3 to an actuator 4 which performs the positioning of the separating edge, and/or to a means for changing the flight trajectories of the particles, in particular to the drive unit of the conveying means 7 and/or to the exciter 5 of the separating force. The data-processing unit 3 may also be designated as a controller or control unit.

[0107] The sensor 2 may have been designed in diverse ways. For example, the sensor may be an optical sensor, such as a light barrier for example (FIG. 5c). But the sensor may also take the form of a pressure-sensitive sensor or acoustic sensor. Depending upon the arrangement, the sensor 2 may have been fixedly connected to the separating edge or it may have been designed to be displaceable relative to the separating edge.

[0108] As in FIGS. 5a, b, and c several sensors 2, 2a, 2b may also have been provided. In FIGS. 5a and 5c, sensor 2 is located in the region of the separating edge, and sensors 2a, 2b have been arranged to be spaced to the left and right in relation to the separating edge. In this case, all three sensors are in communication with the data-processing unit 3. On the basis of the sensor data, said control signal can then be made available on the basis of the measured particle stream and the corresponding sensor position.

[0109] In all embodiments, the at least one sensor 2 has preferentially been arranged in such a manner that it detects a predetermined region (the “detection region” defined above) of the particles appearing but not those particles which lie outside the predetermined region. In a preferred embodiment, the at least one sensor has been arranged in such a manner that it exclusively detects the particles appearing in the region of the separating edge.

[0110] A preferred embodiment of the device according to the invention consists in utilizing as sensor 2 a structure-borne-sound microphone which has been integrated into the separating edge and detects the impact noises of the particles on the separating edge (FIG. 5a). The structure-borne-sound microphone is an example of an acoustic sensor. In order to suppress disturbing impact noises when particles strike the flanks of the splitter 1, said flanks (in particular, the flank on the concentrate side) can be provided with a rubber coating. Alternatively, sensors enter into consideration that detect particles immediately prior to impingement on the separating edge, for example by means of a light barrier or by disturbance of an electric field. Instead of determining the counting-rate directly, the latter can also be derived from other measurements, for example by measurement of the impulse transmitted to the sensor. As a rule, in this case sensor 2 has been rigidly connected to the separating edge.

[0111] The position of the separating edge is preferentially set, for example by means of a worm gear, via the counting-rate. A manual setting of the separating edge, for example on the basis of an acoustic signal, would also be conceivable. But, in principle, in the case of a fixed position of the separating edge there is also the possibility to vary, for example, the speed of the conveying means 7 or the exciter for the separating force 5, in order to influence the flight trajectories of the particles relative to the separating edge.

[0112] A preferred configuration of the method according to the invention consists in that the sensor samples the counting-rate periodically (for example, once per minute) in the neighborhood of the current position of the separating edge (for example, +/−30 cm), and the separating edge is subsequently positioned at the relative minimum of the number-distribution function measured in this way. The particular advantages of this method are evident from FIG. 2. As represented at the top in FIG. 2, coarse material was firstly processed. Subsequently, however, mainly fine-grained material arrives at the eddy-current separator. On account of the steeper flight trajectories of the fine-grained particles, all the material is now discharged in the residue 21—in the original position of the separating edge no separation takes place any longer. However, by virtue of the periodic sampling of the neighborhood of the separating edge the sensor finds the new relative minimum in the number-distribution function (FIG. 2) below, and the separating edge is repositioned there by the data processing.

[0113] In addition to sensor 2, which detects the counting-rate on the separating edge, further sensors 2a and 2b may be installed, as sketched at FIG. 5c. In this case, a displacement of the minimum of q.sub.0(x) in operation could also be measured without periodic sampling, by displacement of the separating edge. In normal operation the central sensor 2 measures a lower counting-rate than the two flanking sensors 2a and 2b. If, however, the counting-rate minimum shifts to the right, for example, the counting-rate of sensor 2b becomes lower than that of 2 and of 2a. In this case, the data processing would displace the sensors further to the right via an actuator until such time as sensor 2 again outputs lower counting-rates than sensors 2a and 2b—that is to say, the new minimum of the number-distribution function has been found. The separating edge is now moved into this position.

[0114] If the particle clouds of the conductive and non-conductive material overlap very considerably, for example as a consequence of a broad grain-size distribution of the material, it may happen that the optimal region for the positioning of the separating edge is marked not by a relative minimum but only by a point of inflection of the number-distribution function (FIG. 3, bottom). In this case, the optimal position of the separating edge would result as the minimum of the first derivative of the number-distribution function q.sub.0(x) with respect to the horizontal spacing x.

[0115] A particular advantage of the device according to the invention is the possibility of the very simple optimization of the position of the separating edge by temporary suppression of the separating force (FIG. 4). The exciter 5 of the separating force is briefly switched off in operation or transferred from its “active position” 5 into a “neutral position” 5a, so that no separating force is acting on the material 10 and consequently no deflection takes place. The material 10, just like the material 11, accordingly follows the trajectories for the horizontal projection—that is to say, those of S1. Subsequently the separating edge with the integrated sensor 2 is moved to the left, starting from an initial position x.sub.0, and positioned at x.sub.min, where the counting-rate just exceeds zero. Subsequently the exciter 5 of the separating force is switched on again or moved back into the active position. In this way, the separating edge was positioned automatically in such a way that only particles 10 overcome the separating edge and are transferred into the concentrate. An analogous way of proceeding may, for example, also be locked into the start-up procedure of the bulk-material sorting plant in such a way that the separating edge has already been positioned before the exciter 5 of the separating force is switched on.

[0116] The exemplary configurations above for an eddy-current separator can, with due alteration of details, be carried over to other sorting appliances with separating edges, as sketched in FIG. 7 for a magnetic-deflection separator or in FIG. 8 for an electrostatic-influence separator.

[0117] With reference to FIG. 5b, the following will also be elucidated: three parallel sensors (preferentially light barriers) have been positioned along the horizontal plane barely above the separating edge and fixedly connected to the latter, the middle sensor being situated approximately above the separating edge (FIG. 5b, top). In order to obtain a high yield or a high concentrate quality, the three sensors may also have been positioned a few centimeters to the side of the separating edge, as shown in FIG. 5b (middle and bottom). In the optimal setting, the counting-rate on the middle sensor is lower than in the two flanking sensors. If this condition no longer obtains, the minimum has obviously drifted. In this case, the separating edge, with the sensors fastened thereto, is traversed until the middle sensor again indicates a minimum in relation to the flanking sensors (alternatively, the speed of the belt is varied minimally without the sensor and the separating edge being moved). The advantage of this arrangement is that it is independent of fluctuations in the charging quantity.

[0118] Alternatively, the sensors have not been fixedly connected to the separating edge, so that the sensors can be traversed independently of the separating edge.

LIST OF REFERENCE SYMBOLS

[0119] 1 splitter with separating edge

[0120] 2 sensor

[0121] 3 data-processing unit

[0122] 4 actuator

[0123] 5 exciter in active position

[0124] 5a exciter in neutral position

[0125] 7 conveying means

[0126] 10 electrically conductive material or particle

[0127] 11 electrically non-conductive material or particle

[0128] 12 bulk-material sorting plant

[0129] 13 bulk-material separator

[0130] 14 bulk-material sorter

[0131] 20 product outlet, concentrate

[0132] 21 product outlet, residue

[0133] S stream of bulk material

[0134] S1 first bulk-material fraction

[0135] S2 second bulk-material fraction