GB2208809A

GB2208809A - A mixing device for road-making or road-repairing materials

Info

Publication number: GB2208809A
Application number: GB8719795A
Authority: GB
Inventors: Arthur James Stenhouse Winter
Original assignee: ROBERT STENHOUSE Co LIMIT
Current assignee: ROBERT STENHOUSE Co LIMIT
Priority date: 1987-08-21
Filing date: 1987-08-21
Publication date: 1989-04-19
Anticipated expiration: 2007-08-21
Also published as: GB8719795D0; GB2208809B

Abstract

A device for mixing materials for surfacing or repairing roads includes a chamber 1, a burner 6 and a fan for supplying a stream 5 of hot gas into the chamber and a hopper 8 in which initially cold aggregate is preheated by heat from the chamber 1 before being admitted through a door 10 into the chamber 1. An emulsion of a binder material in water is admitted to the chamber through a conduit 9. A rotor comprising a shaft 2 and arms 3 carrying paddles 4 mixes the materials in the chamber 1, which the hot mixture leaves when a door 15 is opened. <IMAGE>

Description

A MIXING DEVICB FOR ROAD-MAKING OR ROAD-REPAIRING MATERIALS According to the invention, there is provided a device which is suitable for mixing materials for use in surfacing or repairing roads, the device comprising a chamber, means for supplying a stream of hot gas to the chamber, a rotor within the chamber, an aggregate storage space adjacent to but outside the chamber for receiving a measured quantity of aggregate which will be pre-heated by heat from the chamber, means for causing the pre-heated measured quantity of aggregate to pass from the aggregate storage space into the chamber where it will be whirled around in the hot gas and further heated, means for admitting a measured quantity of an emulsion of binder material and water into the chamber, whereby a mixture of aggregate and binder is formed, and means for causing the mixture to flow out of the chamber when desired.

Preferably the device is such that the materials whilst in the chamber are not exposed to any flame.

An example in accordance with the invention is described below with reference to the accompanying drawings, in which: Figure 1 shows a diagrammatic view, taken from one side, of the interior of part of a mixing device, Figure 2 shows a diagrammatic view, taken from the same side, of the exterior of the mixing device, Figure 3 shows a view, taken from the rear, of a second mixing device, Figures 4 and 5 show views, taken from opposite sides, of the second mixing device, and Figure 6 shows a diagrammatic view, taken from one side, of a third mixing device.

Figure 1 shows a chamber 1 in which is a rotor comprising a shaft 2 along which are distributed eight arms 3, of which only four can be seen, the other four being behind them. Each arm supports a paddle 4 at its outer end.

A stream 5 of very hot gas is blown downwardly into the chamber by a fan (not shown in Figure 1) from a burner 6 which is within a burner hood 6A and burns diesel fuel to produce a flame 7 which does not enter the chamber 1. Consequently, materials in the chamber, to be mixed, are not exposed to any flame.

Adjacent to the chamber 1, but outside it, is a hopper 8 providing a storage space for receiving aggregate 11. The aggregate is separated from the chamber 1 only by a wall 9 and a door 10 and so it is pre-heated, by heat from the chamber 1, to such a temperature that it cannot be held in the hand, and at least some of the water in it is evaporated, before it is admitted into the chamber 1 by opening the door 10. The quantity of aggregate in the hopper is a measured quantity. For example, the hopper may be loaded with a known number of bags of aggregate, each containing a known quantity of aggregate, or the hopper may be loaded until the level of the aggregate reaches a mark on the hopper, when the amount of aggregate in the hopper is a known amount.

A measured quantity of an emulsion 12 of binder material, for example bitumen, in water is admitted to the chamber 1 through a conduit 13 a few seconds after all the pre-heated aggregate in the hopper 8 has been admitted to the chamber 1 by opening the door 10. In those few seconds the aggregate has been further heated and dried by being whirled around in the stream 5 of hot gas. A hot mixture of aggregate and binder is produced in the chamber 1 by a churning action of the paddles 4 and flashed-off water and gases escape from the chamber through a flue 14 which has a fixed lower section 14A and a movable lower section 14B which can be swung down to a position shown in Figures 3 to 5 to enable it to pass under low bridges and other obstacles when the device is travelling on a road.

A discharge opening for discharging the hot 0 mixture, for example at 110 C, is controlled by a discharge door 15 which, when open, allows the hot mixture to fall on to the road or into a container 16 (Figure 2).

The measured quantities of aggregate and emulsion are such that the resultant hot mix is in accordance with a specification. For example, eight bags each containing 25 kilograms of aggregate may be mixed with 16.7 kilograms of emulsion containing 60% by weight of bitumen and 40% by weight of water to produce a mixture of 200 kilograms of aggregate and 10 kilograms of bitumen.

Figure 2 shows the parts 8, 14A, 14B and 15 referred to above and a container 17 for the emulsion, these parts being carried on a trailer having two large road wheels 18, one smaller road wheel 19 and a draw-bar 20 for coupling the trailer to a vehicle carrying cold aggregate and cold emulsion, which vehicle is to tow the trailer. The emulsion is fed from the towing vehicle through a flexible pipe (not shown) and a fixed pipe 21 coupled to it, then through a valve 22 into the container 17 and subsequently through another valve 23 into the chamber 1.

Supports 24 for the trailer can be lowered to engage the ground and the trailer can be jacked up until the road wheels 18 cease to engage the ground. The trailer carries a diesel engine 25, which drives the rotor shaft 2 at constant speed through a chain drive 26 (Figure 4) and also drives the fan at constant speed through a belt drive 27 and pulleys 27A (Figure 4) and the trailer also carries a tank 28 for the diesel fuel for the engine 25 and for the burner 6. A chain 29 supports the container 16, which is open at the top and at the rear end, shown on the right in Figure 2, so that an operative may shovel the hot mix out of it.

Figures 6 shown the parts 6A, 14A, 14B, 15 to 18 and 21 to 25 mentioned earlier, but in a slightly different configuration, also a pipe 30 through which the still rather cold emulsion flows into the conduit 13 and then into the chamber 1. The valves 22 and 23 for the emulsion are operated by long levers 22A and 23A. A lever 31 opens the door 10 to admit the aggregate into the chamber 1 and a control member 32 controls the opening of the door 15 which, in contrast to what is shown in Figures 1 and 2, is preferably so low that all the material in the chamber 1 can flow out of it under gravity when the door 15 is opened. The aggregate and the emulsion are also conveyed into the chamber 1 entirely by gravity.

Another control member is a valve 35 for regulating the supply of fuel to the burner 6.

The emulsion may be supplied to the container 17 until an operative sees that the level in the tank is at one of several graduation marks on the container, according to the mix required, the quantity and nature of the aggregate and the nature of the emulsion, or the emulsion may be automatically metered into the container 17, for example by means of a floating-ball cock as in w.c. cisterns. In either case the entire quantity of emulsion in the container 17 passes into the chamber 1 when the valve 22 is opened.

The pipes carrying the emulsion to the conduit 13 pass above and close to a duct carrying exhaust gases from the engine 25, so that the emulsion is slightly pre-heated before entering the chamber 1. Apart from that, no special steps are taken to pre-heat the emulsion. The aggregate is pre-heated only in the hopper 8.

The emulsion may be a tar emulsion.

The mixing device may be used without an emulsion, for example with cold but flowable bitumen or tar-based medium-curing or rapid-curing cut-backs. Instead of supplying only stone to the hopper 8, there may be supplied to it bituminous or tar-coated aggregate recovered from a road surface, which is then mixed with further binder material, possibly supplied to the chamber 1 in the form of an emulsion, and/or more aggregate. The device can also be used to re-heat a mixture of aggregate and binder which has become cold, whether the binder is cut-back bitumen or cut-back tar or a bitumen emulsion or a tar emulsion. Another use of the device is in drying and/or mixing aggregate, without mixing it with a binder, and another use is in producing slurry seal, i.e.

so-called "flow mixes" with cold bituminous emulsion for small-scale or large-scale sealing or resealing of bituminous or concrete surfaces. Another possibility is to leave the burner 6 switched off and to use the device to produce a cold mix, at ambient temperature, using cut-back or an emulsion, or a cold flow mix such as a slurry seal using cold emulsion.

Claims

CLAIMS:

1. A device which is suitable for mixing materials for use in surfacing or repairing roads, the device comprising a chamber, means for supplying a stream of hot gas to the chamber, a rotor within the chamber, an aggregate storage space adjacent to but outside the chamber for receiving a measured quantity of aggregate which will be pre-heated by heat from the chamber, means for causing the pre-heated measured quantity of aggregate to pass from the aggregate storage space into the chamber where it will be whirled around in the hot gas and further heated, means for admitting a measured quantity of an emulsion of binder material and water into the chamber, whereby a mixture of aggregate and binder is formed, and means for causing the mixture to flow out of the chamber when desired.

2. A device according to claim 1 which is such that the materials whilst in the chamber are not exposed to any flame.

3. A device according to claim 1 including a burner above the chamber, from which burner a flame extends upwardly, and a fan which blows hot gas downwardly into the chamber from the vicinity of the flame.

4. A device according to any preceding claim in which the aggregate storage space is provided by a hopper which is separated from the chamber only by a single wall having a door in it which, when opened, permits the aggregate to be fed by gravity into the chamber.

5. A device according to any preceding claim in which the rotor comprises a shaft along which are distributed radial arms which are angularly spaced around the shaft and carry paddles at their radially outer ends.

6. A device according to any preceding claim in which the means for admitting emulsion is a conduit having openings in its wall from which the emulsion enters the chamber.

7. A device according to any preceding claim having a flue extending upwardly from the upper part of the chamber to carry away from the chamber into the atmosphere flashed-off water and gases, the flue having an upper section which can be folded down to decrease the height of the device for travel.

8. A device according to any preceding claim having a door for the chamber which, when opened, allows the hot mixture produced in the chamber to leave it under gravity.

9. A device according to any preceding claim in which the rotor is driven by a diesel engine and its exhaust gases flow along a duct near the flow of emulsion to the chamber so that the emulsion is pre-heated before entering the chamber.

10. Apparatus comprising a device according to claim 6 mounted on a first vehicle, the upstream end of the conduit being connected by a flexible pipe to a vessel containing cold emulsion and situated on a second vehicle which tows the first vehicle.

11. A device which is suitable for mixing materials for use in surfacing or repairing roads, substantially as hereinbefore described with reference to Figures 1 and 2 or Figures 3 to 5 or Figure 6 of the accompanying drawings.