GB2302866A

GB2302866A - Process and Apparatus for Recycling Airborne Particulate Matter

Info

Publication number: GB2302866A
Application number: GB9513354A
Authority: GB
Inventors: Edward Joseph Polhill
Original assignee: LANTON PARK Ltd
Current assignee: LANTON PARK Ltd
Priority date: 1995-06-30
Filing date: 1995-06-30
Publication date: 1997-02-05
Also published as: GB2302866A8; GB9513354D0

Abstract

The invention relates to apparatus 1 for recycling airborne particulate matter such as dust for use with a material delivery system (2, Fig 2), comprising a conduit 3, and drive means 4 for conducting airborne particulate matter from a delivery point 5 of the system 2, the conduit 3 being adapted for connection, in use, to a container 6 of the system 2 for transport thereto of the airborne particulate matter. The material in the container 6 is of larger particle size than the airborne matter and preferably wetted to enable mixing. Preferably the conduit outlet is an open ended 9, steel mesh 8, downwardly pointing cylinder. The delivery system is preferably a batch concrete making plant with the dust being returned to the aggregate container.

Description

1 A PROCESS AND APPARATUS FOR RECYCILING AIRBORNE PARI1CULATE MATTER

2302866 This invention relates to a process for recycling airborne particulate matter in a material delivery system and to apparatus for carrying out the process.

Many industrial processes involve the mixing of granular or powdered constituents. The constituents are often stored in bulk storage silos, and mixing occurs upon delivery of the constituents to a mixing vessel. A problem which has been experienced with such apparatus is the release, on transfer of the constituents, of fine powders or particles which become suspended in the air space around the apparatus, resulting in a loss of raw material, a hazard to the health of personnel, and the coating and clogging of peripheral apparatus. It is an object of the invention to seek to mitigate problems such as these.

According to the invention there is provided a process for recycling airborne particulate matter in a material delivery system, comprising the steps of delivering material, extracting airborne particulate matter liberated thereby and conducting the matter to a container of the delivery system containing material of a larger average particle size for mixing therewith.

The invention provides a process which not only overcomes the problems of airborne dust and powder contaminating the working area, but also is further environmentally friendly in that the powder which would otherwise be lost or discarded is effectively recycled back into the system via the material of a larger average particle size.

It is preferred that the airborne particulate matter is substantially disbursed in the container. This ensures a better mixture of the constituents upon ultimate 2 delivery by the system.

It is particularly preferred that the airborne particulate matter is extracted and conducted to the container via an airstream. This aids dispersal in the container and is an efficient and effective method of removing the airborne particulate matter from the air space around the delivery system.

It is preferred that the process comprises extraction of airborne particulate matter comprising one or a mixture of cement dust, powder, concrete dust, concrete powder, pulverised fly ash and/or lime. It is further preferred that the material of a larger average particle size comprises an aggregate used in concrete making. It is also preferred that the material of a larger average particle size is wet.

According to one preferred embodiment, the material for delivery by the system preferably comprises the constituents of concrete. The process may conveniently be operated in a concrete producing plant.

According to a second aspect of the invention, there is provided apparatus for recycling airborne particulate matter for use with a material delivery system, comprising a conduit, and drive means for conducting airborne particulate matter from a delivery point of the system, the conduit being adapted for connection, in use, to a container of the system for transport thereto of the airborne particulate matter. The conduit may include outlet means through which the airborne particulate matter passes into the container in use, the outlet means being adapted for dispersal thereof.

It is preferred that the outlet means is adapted to substantially prevent blocking thereof by the contents of the container.

3 Ile outlet means may comprise a mesh, and the mesh may be in the form of a downwardly (in use) extending open ended cylinder. Alternatively, the outlet means may comprise a flared part.

According to a third aspect of the invention there is provided a unit for use in a.plant, comprising apparatus as described hereinabove.

According to a fourth aspect of the invention there is provided a plant including apparatus as hereinbefore defined.

A process and apparatus embodying the invention are hereinafter described, by way of example, with reference to the accompanying drawings, in which:Fig. 1 is a schematic representation of apparatus according to the invention; Fig. 2 is a side view of a plant fitted with the apparatus of Fig. 1; Fig. 3 is a plan view of the plant of Fig. 2; and Fig. 3 is an end view of the plant of Figs. 2 and 3.

Referring to the drawings there is illustrated apparatus 1 for recycling airborne particulate matter for use with a material delivery system 2, comprising a conduit 3, and drive means 4 for conducting airborne particulate matter from a delivery point 5 of the system 2, the conduit 3 being adapted for connection, in use, to a container 6 of the system 2 for transport thereto of the airborne particulate matter.

As illustrated, the conduit 3 connects the constituent delivery area of the plant 4 2 with an aggregate silo 6, (or silos). At the delivery end, the conduit may have a dust extraction shroud 7 which may assist in dust collection. The conduit 3 is provided with an air impeller of any suitable form known in the art, such as for example an 18 kilowatt 2,800 rpm fan. The conduit itself may comprise any suitable form of ducting known in the art. Where it enters the silo 6 the conduit may have a specially formed outlet designed to aid in dispersion of the powder through the contents of the silo 6, and also to prevent clogging of the outlet. In the illustrated embodiment, the conduit is provided with a downwardly (in use) oriented cylinder comprising a high tensile steel mesh 8, which is open ended 9. The outlet is positioned substantially above an outlet of the silo 10 which is provided with a ram 11 for opening and closing.

Referring to Figs. 2 to 4, the apparatus 1 is shown installed in a batch plant used in the production of batches of concrete for delivery to mixer lorries. The plant 2 is of conventional design, incorporating bulk storage silos for aggregate and cement and other ingredients of concrete.

In operation, when a mixer lorry enters the plant, the concrete constituents are loaded via chutes 12. The constituents mix as they enter the lorry. As will be appreciated, the mix comprises cement, along with a conglomerate of gravel, pebbles, sand, broken stone, blast furnace slag or cinders termed the aggregate as well as additives such as pulverised fly ash and lime. Water is also added to the mix. During delivery, a quantity of fine dust from the cement, aggregate, and other additives becomes airborne. The drive means 4, in this case a fan, is operated to suck the dust-contaminated air via the shroud 7 into the conduit 3 whence it is piped to the aggregate silo 6. "I'lie air and suspended particles are blown into the silo where dispersal throughout the aggregate occurs due to the airstream forcing the suspended particulate matter through the interstices in the aggregate. The particles coat the larger aggregate particles, clinging to their surfaces, and thereby when delivery of the next batch of aggregate occurs, substantially all of the previously airborne suspended particulate matter passes with the aggregate in the next batch to be delivered, and virtually none escapes back into the air. The process is assisted if the aggregate is pre-wetted, as this aids adherence of the airborne particulate matter to the aggregate.

In a variation, the drive means 4 can be automatically operated to coincide with operation of the delivery system. In addition, it will be appreciated that the apparatus according to the invention can easily be retrofitted to existing plants in which airborne particulate matter may be a problem.

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Claims

CLAIMIS

1. A process for recycling airborne particulate matter in a material delivery system, comprising the steps of delivering material, extracting airborne particulate matter liberated thereby, and conducting the matter to a container of the delivery system containing material of a larger average particle size for mixing therewith.

2. A process according to Claim 1, wherein the matter is substantially dispersed in the container.

A process according to Claim I or Claim 2, wherein the particulate matter is conducted to the container via an airstream.

4. A process according to any preceding claim, wherein the airborne particulate matter comprises one or a mixture of cement dust, powder, concrete dust, pulverised fly ash arid/or lime.

5. A process according to any preceding claim, wherein the material of a larger average particle size comprises an aggregate used in concrete making.

6. A process according to any preceding claim, wherein the material of a larger average particle size is wet.

7. A process according to any preceding claim, wherein the material for delivery by the system comprises the constituents of concrete.

8. A process according to any preceding claim, in operation in a concrete producing plant.

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9. Apparatus for recycling airborne particulate matter for use with a material delivery system, comprising a conduit, and drive means for conducting matter from a delivery point of the system, the conduit being adapted for connection, in use, to a container of the system for transport thereto of the airborne particulate matter.

10. Apparatus according to Claim 9, wherein the conduit includes outlet means through which the airborne particulate matter passes into the container, in use, the outlet means being adapted for dispersal thereof.

11. Apparatus according to Claim 10, the outlet means being adapted to substantially prevent blocking thereof by the contents of the container.

12. Apparatus according to Claim 10 or Claim 11, wherein the outlet means comprises a mesh.

13. Apparatus according to Claim 12, wherein the mesh is in the form of a downwardly (in use) extending open ended cylinder.

14. Apparatus according to any of Claims 10 to 12, wherein the outlet means comprises a flared part.

15. Apparatus according to any preceding claim, wherein the drive means comprises a fan.

16. Apparatus substantially as hereinbefore described, with reference to the accompanying drawings.

17. A unit for use in a plant, comprising apparatus according to any of claims 8 9 to 16.

18.

A plant, including apparatus according to any of claims 9 to 16.

19. A plant, substantially as hereinbefore defined with reference to Figures 2 to 4 of the drawings.