Settling apparatus

Abstract: A settling apparatus for the separation of amalgam from waste water in a dental procedure includes an inclined passage through which the water is caused to flow from below and upwards while depositing amalgam. The inclined passage (9A) has an inclination of between 3° and 15°. It is filled with a large number of thin-walled, narrow tubes (17), which contact each other in a side-by-side manner. The water flows from below and upwards through the tubes and through the channels between the tubes while amalgam is settled and deposited on the interior, as well as on the exterior, surfaces of the tubes.

Description: This invention relates to a settling apparatus for removing amalgam from waste water produced in a dental procedure, comprising an inclined passage having an inclination to the horizontal of from about 3° to 15°; a plurality of tubes having circular cross section, extending through said passage, substantially all of the tubes contacting other tubes in a side-by-side manner and forming channels therebetween; and means for flowing said waste water from a lowermost end of said passage, through said tubes in laminar flow and out of said passage, wherein amalgam in said waste water is settled in said tubes. BACKGROUND OF THE INVENTION Several different embodiments of settling apparatus comprising a plurality of parallel and inclined settling canals separated by lamellar elements are known to the art. By way of example may be mentioned those apparatuses which are described in the U.S. patents Nos. 2,868,384, 3,494,475, 3,741,892, and in the German patent No. 3 010 365. It is also known to utilize tubular settling channels, according to Swedish patent No. 352 243. Those apparatus which so far have been used in practice, however, have not satisfactorily met the specific demands which are required for settling apparatus intended for the separation of amalgam from waste water in dentists' practices, i.e. for applications where there is a comparatively small flow of water. The known apparatus either have been designed for very large installations and to comply with those specific demands which are raised in connection with such large installations, or they do not have satisfactory separation efficiency. GB-A-1 238 489 describes a settling apparatus of said large size type. US-A-4 529 383 relates to a gravity separator for use in dental suction apparatus. FR-A-1 568 571 describes a rotary- and labyrinth type of separator. EP-A-0 096 670 relates to a filter apparatus for separating for example amalgam from waste water. US-A-2 613 811 describes a continuous settling apparatus. BRIEF DESCRIPTION OF THE INVENTION The purpose of the invention is to provide a small, handy apparatus which can satisfy the specific demands which are required for apparatus for the separation of amalgam from the waste water from a dentist's practice or the like. Among these demands may be mentioned that the apparatus must have small dimensions, be inexpensive and simple to use, and have a very high separation efficiency as far as amalgam is concerned. It is also a purpose of the invention that the apparatus, when it has been filled with removed amalgam to a certain degree, shall be readily reconditioned for further use. These and other objects may be achieved therein that the apparatus comprises in series, and in fluid connection with each other, a presettling chamber, an inlet chamber to said inclined passage, and said inclined passage; that said inclined passage has at least a bottom wall extending in the longitudinal direction of the passage, and an end wall (13, 46) in the inlet end of the passage; that said end wall consists of a perforated partition wall provided between said inlet chamber and said inclined passage; that the inclined passage has a cross-section of between 2000 and 20000 mm²; that the tubes extend in said inclined passage parallel to said bottom wall, resting at their lowermost ends against said perforated partition wall; that the inclined passage and the tubes resting against the perforated partition wall have a length of about 100-400 mm; and that the tubes have an internal diameter of between 1 and 4 mm, and a wall thickness of not more than 0.5 mm, wherein amalgam may be deposited by settling or by direct contact not only on the interior, but also on the exterior of the tubes. Preferably the passage and hence the tubes have an inclination of 5-10°. According to a preferred embodiment the settling apparatus comprises a pre-settling chamber, which has a larger volume than the inclined passage which contains the tubes, and the inclined passage, according to a preferred embodiment, is part of a separate unit or cassette which can be removed from and replaced in the main part of the apparatus. By exchange of cassettes the apparatus can be reconditioned quickly when the tubes and the passage between the tubes have been loaded with amalgam to a predetermined degree. The exchange of cassettes may, for example, be made regularly and rather frequently according to a certain time schedule, while the cleaning of the larger pre-settling chamber may be performed less frequently. The cassette may consist of a cylindrical barrel in the form of a thicker outer tube, which, at least in that end thereof which is lowermost when the cassette is mounted in or on the settling apparatus, is provided with a bottom plate against which the narrow tubes may rest inside the thicker outer tube. In fluid communication with this bottom plate there may be provided a pre-chamber which communicates with the pre-settling chamber. Further, according to another embodiment of the invention, the exterior of the apparatus may consist of a housing having upper and lower compartments, with the upper end lower compartments being separated from each other by an inclined partition wall. The inclination of the inclined partition wall is equal to the inclination of the inclined passage, which is provided in the lower compartment beneath the inclined partition wall, together with an inlet chamber for the inclined passage. The upper compartment defines a pre-settling chamber and a conduit is provided through the inclined partition wall in the lower part thereof between the pre-settling chamber in the upper compartment and the inlet chamber in the lower compartment. According to this embodiment, the tubes in the inclined passage rest directly or indirectly on support members provided in the lower compartment. Further features and aspects of the invention will be apparent from the appending claims and from the following description of a preferred embodiments. BRIEF DESCRIPTION OF DRAWINGS In the following description of preferred embodiments reference will be made to the accompanying drawings, in which Fig. 1 is a side view of a settling apparatus according to a first preferred embodment; Fig. 2 is an end view of Fig. 1; Fig. 3 shows a cross-sectional view of a settling cassette forming part of the settling apparatus, along the line III-III in Fig. 1; Fig. 4 shows a cross-sectional view of the settling cassette along the line IV-IV in Fig. 3; Fig. 4A shows enlarged details of Fig. 4; Fig. 5 is a top view of a settling apparatus according to a second preferred embodiment; and Fig. 6 shows a vertical section through the settling apparatus along the lines VI-VI in Fig. 5. With reference to Fig. 1 and Fig. 2 the main part of the settling apparatus according to the first embodiment is designated 1. In this main part there is a pre-settling chamber 2 having an inlet conduit 3 and an outlet conduit 4 for waste water. Further there is provided a clean-out lid 5 on one side of the pre-settling chamber. On the other side of the main part 1 there is provided an inclined recess 6, in which there is provided a removable cassette 7, which is secured in the recess 6 by means of a pair of rubber bands 8. The inclination of the recess 6 defines the inclination of the cassette 7, which is, in a most preferred embodiment, about 7° to the horizontal plane. The cassette 7 consists of an outer cylindrical barrel 9, which according to the embodiment has a circular cross section, although a rectangular and other cross-sections may be used. In each end of the barrel 9 there is a cap, e.g. a screw cap 10 and 11, respectively. As shown in Figure 3, fastened between circular abutment surface 12 on the inside of caps 10 and 11, respectively, and the outside of barrel 9 are perforated plates, e.g. circular wire screens 13 and 14, respectively. Between these screens 13, 14 and the end portions of the caps 10 and 11 there is provided a lower inlet pre-chamber 15, and an upper end chamber 16, respectively. The interior, inclined passage 9A (see Figures 4 and 4A) of the barrel 9 is filled with a plurality of small diameter, narrow, thin-walled plastic tubes 17, which are in a number that they contact each other in a side-by-side manner and in a more or less regular pattern and extend through the barrel 9, so that channels are formed between the tubes. The sizes of these channels may vary somewhat depending on irregularities in the arrangement of the tubes and also on the number of tubes, i.e. on how closely the tubes are packed. According to a preferred embodiment the tubes have a diameter of about 2.5 mm and a wall thickness of 0.5 millimeter or less, e.g. only a few tenths of a millimeter, i.e. a thickness which can be neglected with regard to the cross-section of passage 9A. The tubes 17 rest at their lowermost ends against the lower screen 13. Preferably the tubes 17 have the same length as the barrel 9 and are secured between the two screens 13 and 14. The previously mentioned outlet conduit 4 from the pre-settling chamber 2 is connected to an inlet opening 20 of the lower inlet pre-chamber 15, and a discharge conduit 21 for clarified water is connected to a discharge opening 22 in the end wall of the upper end-chamber 16. When the settling apparatus is in use, waste water containing amalgam is flowed through the conduit 3 to the pre-settling chamber 2. Larger lumps of amalgam, tooth chips and other larger solid objects have been separated from this waste water by screening in a previous operation. The main part of remaining amalgam is deposited on the bottom of the pre-settling chamber 2. From the pre-settling chamber 2 the water is flowed to the cassette 7. In the inclined passage 9A in the cassette 7 the water is caused to flow slowly upwards from the pre-chamber 15 through the screen 13, and further through the large number of tubes 17 as well as through the spaces 18 between these tubes 17 and up to the upper end-chamber 16 and further out through the discharge conduit 21. Due to the facts that the tubes 17 are narrow and that water also passes between the tubes in the spaces 18, laminar flow of the water is achieved. The laminar flow in combination with the low flow speed of the water and the small inclination, preferrably about 7°, of cassette will cause even extremely small amalgam particles to be deposited by settling or by direct contact on the exterior, as well as on the interior, surfaces of the walls of the tubes 17. The flow of the waste water through the apparatus may be caused by any convenient means, such as by gravity, by syphon action, by pumps or the like. When the cassette 7 has been filled with amalgam to a certain degree or when the settling process has been conducted for a certain pre-determined period of time, the cassette 7 is removed and is replaced by a new cassette containing clean tubes 17. The used cassette is sent to a commercial plant for recovery of the amalgam. At certain intervals, also the pre-settling chamber 2 is cleaned with respect to the amalgam which has been collected in pre-settling chamber 2. With reference now to Fig. 5 and Fig. 6 a settling apparatus of a second embodiment is general designated 30. All the parts of the apparatus are enclosed in a housing 31 consisting of two identical main parts, namely an upper half 32 of the housing, and a lower half 33. The two halves 32 and 33 consist of injection molded plastic material and may be made in the same molding tool or die which reduces the production cost. The two halves 32 and 33 are secured to each other along an inclined parting plane, for example, by clamping together the two halves along a circumferential edge portion of an inclined partition wall 34 in said inclined plane. The inclined partition wall 34 may consist of rubber or a polymeric material which may serve as a gasket between the two halves 32 and 33. The inclined partition wall 34 has an inclination of between 3° and 15°, preferably between 5° and 10° or for example 7°, with respect to the horizontal. The compartment in the housing 31 above the inclined partition wall 34 constitutes a pre-settling chamber 35 and may correspond to 50% of the whole volume of the housing 31. The pre-settling chamber 35 has an inlet 36 in the top portion or roof 37 of the pre-settling chamber 35 in the region of the top portion which is nearer of the inclined partition wall 34. In the bottom part of the inclined partition wall 34 there is provided a communication conduit 38 extending through the partition wall, establishing fluid communication between the pre-settling chamber 35 and an inlet chamber 39 beneath the inclined partition wall 34. Further, vertical baffles 40A, 41A, 42A extend downwards from the roof 37 between the inlet conduit 36 and the communication conduit 38, the length of said baffles 40A, 41A, and 42A successively being longer in relation to the slope of the inclined partition wall 34, as shown in Figure 6. In the bottom compartment defined by the lower half 33, which is preferrably of the same size and configuration as the upper half 32, there are also vertical partition walls 40B, 41B, and 42B corresponding to the baffles 40A-42A in the upper compartment. The partition walls 40B-42B serve as supports for an inclined plate 43 which is parallel with the inclined partition wall and rests on said supports 40B-42B. Between the inclined partition wall 34 and the inclined plate 43 there is an inclined passage 44 which has the same inclination as the inclined partition wall 34 and the inclined plate 43. The inclined passage 44 extends between the longitudinal side walls of the housing 31. In the lower end of the inclined passage 44 there is provided the inlet chamber 39 and in the upper end there is correspondingly provided an outlet chamber 45. The inlet chamber 39 is defined by a screen 46 which is integrated with top and bottom distance members 47 and 48, which contact the end wall of the housing 31. The outlet chamber 45 is correspondingly defined by a screen 50 and upper and lower space members 51 and 52, respectively. In the region of the outlet chamber 45 there is provided a discharge opening 53. The passage 44 is filled with tubes 55 of the same type as have been explained in connection with the above described first embodiment. Like the tubes in the said first embodiment, the tubes 55 contact each other in a side-by-side manner so that, preferrably, the whole volume of the passage 44 is filled with the tubes 55, and also so that channels are formed between the contacting tubes in a more or less regular pattern. When the settling apparatus 30 is in use, water containing amalgam is fed through inlet 36 to the pre-settling chamber 35 where the main part of amalgam existing in the waste water is deposited on the inclined partition wall 34, wherein the baffles 40A, 41A, and 42A contribute to a flow pattern of water in the pre-settling chamber 35 which is advantageous to the settling procedure. From the pre-settling chamber 35 the waste water is fed via conduit 38 through the bottom part of the inclined partition wall 34 to the inlet chamber 39 beneath the lowermost part of the partition wall 34. From the inlet chamber 39 the waste water flows through the screen 46 and further through the large number of tubes 55 as well as through the channels between the tubes 55 and up to the outlet chamber 45 and out through the discharge conduit 53. In the inclined passage 44, which according to this embodiment has a rectangular cross section, the water will have laminar flow, as according to the previous embodiment, wherein even extremely small amalgam particles are deposited by settling or by direct contact on the exterior, as well as on the interior, surfaces of the walls of the tubes 55. When the space 44 has been filled with amalgam to a certain degree or when the settling process has been conducted for a certain predetermined period of time, the apparatus is demounted; amalgam which has collected in the pre-settling chamber 35 is removed, and the tubes 55 are replaced by new ones, which may be in a cassette form, whereafter the apparatus is re-assembled.

Claims: A settling apparatus for removing amalgam from waste water produced in a dental procedure, comprising an inclined passage (9A, 44) having an inclination to the horizontal of from about 3° to 15°; a plurality of tubes (17, 55) having circular cross section, extending through said passage, substantially all of the tubes contacting other tubes in a side-by-side manner and forming channels therebetween; and means for flowing said waste water from a lowermost end of said passage, through said tubes in laminar flow and out of said passage, wherein amalgam in said waste water is settled in said tubes, characterized in that the apparatus comprises in series, and in fluid connection with each other, a presettling chamber (2, 35), an inlet chamber (15, 39) to said inclined passage, and said inclined passage; that said inclined passage has at least a bottom wall (43) extending in the longitudinal direction of the passage, and an end wall (13, 46) in the inlet end of the passage; that said end wall consists of a perforated partition wall (13, 46) provided between said inlet chamber and said inclined passage; that the inclined passage has a cross-section of between 2000 and 20000 mm²; that the tubes extend in said inclined passage parallel to said bottom wall, resting at their lowermost ends against said perforated partition wall; that the inclined passage and the tubes resting against the perforated partition wall have a length of about 100-400 mm; and that the tubes have an internal diameter of between 1 and 4 mm, and a wall thickness of not more than 0.5 mm, wherein amalgam may be deposited by settling or by direct contact not only on the interior, but also on the exterior of the tubes. Apparatus according to claim 1, wherein the inclined passage forms part of a cassette (7), which can be removed from the main part of the settling apparatus. Apparatus according to claim 2, wherein said main part contains said presettling chamber (2). Apparatus according to claim 1, wherein the apparatus includes a housing (31) having upper and lower compartments separated from each other by an inclined partition wall (34), the inclination of said inclined partition wall being equal to the inclination of said inclined passage (44), and wherein the inclined passage is disposed in the lower compartment and beneath said inclined partition wall and an inlet chamber (39) for said inclined passage is in fluid communcation with said passage, and wherein the upper compartment defines a pre-settling chamber (35), and a conduit (38) is provided through said inclined partition wall (34) in the lowermost part thereof between the pre-settling chamber in the upper compartment and the inlet chamber in the lower compartment. Apparatus according to claim 4, wherein the circumferential edge portion of the inclined partition wall is clamped between an upper half (32) of the housing defining said upper compartment and a lower half (33) of the housing defining said lower compartment, and wherein the inclined partition wall also serves as a gasket between said upper and lower halves. Apparatus according to claim 4, wherein the inclined passage (44) is supported on members (40B, 41B, 42B) provided in said lower compartment. Apparatus according to claim 6, wherein vertical partition walls (40A-42A, 40B-42B) are provided in the upper and lower compartments, extending downwardly from a roof (37) of the upper compartment and upwards from a bottom of the lower compartment, respectively, and an inlet conduit (36) to said pre-settling chamber is provided in the part of the pre-settling chamber which is opposite that part where said conduit (38) between the pre-settling chamber and said inlet chamber is located, said partition walls in the upper compartment serving as baffle-members in the pre-settling chamber, and said partition walls in the lower compartment serving as support members for said inclined passage, the vertical length of said vertical partition walls in the pre-settling chamber increasing with the slope of the inclined partition wall from the inlet conduit (36) to the said conduit from the pre-settling chamber to the inlet chamber (39), and the vertical length of said vertical partition walls in the lower compartment increasing along the length of the inclined passage in relation to the inclination of the inclined partition wall.

Inventors: SUNDSTROEM GUSTAF FOLKE, SUNDSTROEM, GUSTAF FOLKE, Sundström, Gustaf Folke
Applicants: STIFTELSEN CT FOER DENTALTEKNI, STIFTELSEN CENTRUM FOER DENTALTEKNIK OCH BIOMATERIAL I HUDDINGE
Application year: 1991
Main classification: B01D21
IPC codes: B01D21