GB1590788A - Magnetic separators - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO MAGNETIC SEPARATORS (71) We, INTERNATIONAL RESEARCH & DEVELOPMENT COMPANY LIMITED, a British Company, of Fossway, Newcastle upon Tyne NE6 2YD, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a magnetic separator and is particularly, although not exclusively, applicable to separators for the extraction of magnetic particles, relatively non-magnetic particles or with suitable pretreatment non-magnetic particles from a fluid stream.

It is well-known in magnetic separators to employ a filter matrix within an electromagnetic structure, the structure including electric coils which induce an electromagnetic field in the matrix. The matrix is made of a material which enables high field gradients to be set-up, so that when a fluidised stream containing magnetic or paramagnetic partices is directed through the matrix, via inlet and outlet manifolds, the arrangement has the effect of extracting the particles from the fluid and retaining these particles within the matrix. The fluid may be in the form of a slurry and the strength of the magnetic field is dependent upon the nature of the fluid and the particles to be removed. The preferred form of filter comprises a canister containing a quantity of ferromagnetic material such as stainless steel wool; other material such as steel balls may, however, be employed.

At various stages of a magnetic separation process it is usually necessary to clean the filter matrix of entrapped material in order to maintain separation efficiency and a number of solutions of this problem have been employed, including back-flushing either in the absence of any magnetic field or with the aid of an alternating magnetic field.

This present invention has the object to provide a construction which not only improves the efficiency of separation but is so constructed that removal of the filter matrix is such a simple operation that filter replacement may be considered as an alternative to the cleaning process referred to above. The removed filter matrix can subsequently be cleaned for re-use.

According to the present invention a magnetic separator comprises a ferromagnetic structure constructed to define a central passage, a filter matrix contained in the passage, an electromagnetic coil housed within the ferromagnetic structure around the passage to create a magnetic field in the matrix, an inlet and outlet connected to one end of the said passage for the introduction of fluid to be treated into the matrix and removal of treated fluid therefrom and a removable cover closing the other end of the said passage to allow removal of the matrix following removal of the cover.

Preferably means are provided which divide the matrix into an inflow portion leading from the inlet towards the said other end of the passage and a return portion leading back to the outlet. Such dividing means may comprise a tubular wall, preferably forming a continuation of the inlet conduit, extending axially through the matrix, the removable cover defining a space for flow from the inflow portion to the return portion of the matrix.

An embodiment in accordance with the invention will now be described, by way of example only, with reference to the drawing accompanying the provisional specification which is a diagrammatic cross-sectional elevation of a magnetic separator for the treatment of slurry containing magnetic or paramagnetic particles.

The separator comprises an annular iron core 10 which has a central bore 11 and a counter bored recess 12 which accommodates an electromagnetic coil 13. The coil 13 is connected to a direct current supply for energisation to produce a high magnetic field gradient within a matrix 16 of stainless steel wool which is divided into a central cylindrical portion 14 and a surrounding toroidal portion 15 contained in respective perforated canisters (not shown). Perforated plates 17, 18 are provided to assist in directing the flow of process fluid and to positionally locate the canisters.

The lower end of the separator is connected to an inlet supply of process fluid and an outlet for directing processed fluid away from the separator. The arrangement comprises a manifold 19 secured to the bottom of the iron core 10 by flanges 19a and includes an inlet pipe 20 which passes in liquid tight manner through the lower wall of the manifold 19. The inlet pipe 20 passes through the manifold 19 and leads to a central pipe 21 which directs the inlet flow through the central matrix portion 14 into a space 22 defined by a removable cover 23 at the opposite end of the matrix. The internal surface of the cover 23 is so shaped that the flow of process fluid is reversed to flow downwards through the matrix portion 15, as shown by flow arrows, into the manifold 19 and thence through an outlet pipe 24 connected in the side wall of manifold 19.

In operation the magnetic coil is energised by a direct current supply so as to generate high magnetic field gradients within the matrix 16 so that the process fluid in flowing through the separator has the magnetic or paramagnetic particles removed. The counter-flow path which this construction provides increases the efficiency of separation and access to the filter matrix for replacement is not impeded by pipework as employed in other known constructions.

The invention is not restricted to the constructional features described above. Thus the arrangement described may be inverted so that the filter matrix is removed from the bottom of the assembly. The connection of process fluid may also be reversed to reverse the fluid flow path so that the outlet pipe 24 becomes an inlet and inlet pipe 20 becomes an outlet.

Further advantages of the arrangement described are that the effective length of the separator is increased by virtue of the counterflow path and also, if required, different grades of filter material can be employed in the inner and outer portions of the matrix.

It will be seen that in the preferred construction the end of the central inlet pipe runs up through the lower perforated plate to define above that plate a central space into which a cylindrical matrix enclosed in a perforated canister can be inserted. Between the outer wall of the end of the pipe and the wall of the bore in the iron core an annular space is defined to receive a matrix of corresponding shape which is also conveniently enclosed in a perforated canister.

The canisters are held in place by the upper perforated plate but can easily be removed either with the upper plate or after removal thereof. Both perforated plates are best made of ferromagnetic material to aid the passage of magnetic flux through the matrices.

WHAT WE CLAIM IS: 1. A magnetic separator comprising a ferromagnetic structure constructed to define a central passage, a filter matrix contained in the passage, and electromagnetic coil housed within the ferromagnetic structure around the passage to create a magnetic field in the matrix, an inlet and outlet connected to one end of the said passage for the introduction of fluid to be treated into the matrix and removal of treated fluid therefrom and a removable cover closing the other end of the said passage to allow removal of the matrix following removal of the cover.

2. A magnetic separator as claimed in claim 1 including means dividing the matrix into an inflow portion leading from the inlet towards the said other end of the passage and a return portion leading back to the outlet.

3. A magnetic separator as claimed in claim 1 in which the said dividing means comprises a tubular wall extending axially through the matrix, the removable cover defining a space for flow from the inflow portion to the return portion of the matrix.

4. A magnetic separator as claimed in claim 4 in which the ends of the said passage are closed by perforated plates of ferromagnetic material, the space between the perforated plates being filled by the matrix and the tubular wall extending between the plates in continuation of an inlet conduit.

5. A magnetic separator as claimed in claim 3 or 4 in which the removable cover is shaped to direct the flow from the inflow portion to the return portion of the matrix.

6. A magnetic separator as claimed in any of the preceding claims in which the inflow and return portions of the matrix are enclosed in separate perforated metal canisters.

7. A magnetic separator substantially as described with reference to the drawing accompanying the provisional specification.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. directing the flow of process fluid and to positionally locate the canisters. The lower end of the separator is connected to an inlet supply of process fluid and an outlet for directing processed fluid away from the separator. The arrangement comprises a manifold 19 secured to the bottom of the iron core 10 by flanges 19a and includes an inlet pipe 20 which passes in liquid tight manner through the lower wall of the manifold 19. The inlet pipe 20 passes through the manifold 19 and leads to a central pipe 21 which directs the inlet flow through the central matrix portion 14 into a space 22 defined by a removable cover 23 at the opposite end of the matrix. The internal surface of the cover 23 is so shaped that the flow of process fluid is reversed to flow downwards through the matrix portion 15, as shown by flow arrows, into the manifold 19 and thence through an outlet pipe 24 connected in the side wall of manifold 19. In operation the magnetic coil is energised by a direct current supply so as to generate high magnetic field gradients within the matrix 16 so that the process fluid in flowing through the separator has the magnetic or paramagnetic particles removed. The counter-flow path which this construction provides increases the efficiency of separation and access to the filter matrix for replacement is not impeded by pipework as employed in other known constructions. The invention is not restricted to the constructional features described above. Thus the arrangement described may be inverted so that the filter matrix is removed from the bottom of the assembly. The connection of process fluid may also be reversed to reverse the fluid flow path so that the outlet pipe 24 becomes an inlet and inlet pipe 20 becomes an outlet. Further advantages of the arrangement described are that the effective length of the separator is increased by virtue of the counterflow path and also, if required, different grades of filter material can be employed in the inner and outer portions of the matrix. It will be seen that in the preferred construction the end of the central inlet pipe runs up through the lower perforated plate to define above that plate a central space into which a cylindrical matrix enclosed in a perforated canister can be inserted. Between the outer wall of the end of the pipe and the wall of the bore in the iron core an annular space is defined to receive a matrix of corresponding shape which is also conveniently enclosed in a perforated canister. The canisters are held in place by the upper perforated plate but can easily be removed either with the upper plate or after removal thereof. Both perforated plates are best made of ferromagnetic material to aid the passage of magnetic flux through the matrices. WHAT WE CLAIM IS:

1. A magnetic separator comprising a ferromagnetic structure constructed to define a central passage, a filter matrix contained in the passage, and electromagnetic coil housed within the ferromagnetic structure around the passage to create a magnetic field in the matrix, an inlet and outlet connected to one end of the said passage for the introduction of fluid to be treated into the matrix and removal of treated fluid therefrom and a removable cover closing the other end of the said passage to allow removal of the matrix following removal of the cover.

2. A magnetic separator as claimed in claim 1 including means dividing the matrix into an inflow portion leading from the inlet towards the said other end of the passage and a return portion leading back to the outlet.

3. A magnetic separator as claimed in claim 1 in which the said dividing means comprises a tubular wall extending axially through the matrix, the removable cover defining a space for flow from the inflow portion to the return portion of the matrix.

4. A magnetic separator as claimed in claim 4 in which the ends of the said passage are closed by perforated plates of ferromagnetic material, the space between the perforated plates being filled by the matrix and the tubular wall extending between the plates in continuation of an inlet conduit.

5. A magnetic separator as claimed in claim 3 or 4 in which the removable cover is shaped to direct the flow from the inflow portion to the return portion of the matrix.

6. A magnetic separator as claimed in any of the preceding claims in which the inflow and return portions of the matrix are enclosed in separate perforated metal canisters.

7. A magnetic separator substantially as described with reference to the drawing accompanying the provisional specification.