WO2011074985A1

WO2011074985A1 - Bitumen particles

Info

Publication number: WO2011074985A1
Application number: PCT/NO2010/000463
Authority: WO
Inventors: John Charles GRØNLI
Original assignee: Universitetet I Stavanger
Priority date: 2009-12-18
Filing date: 2010-12-15
Publication date: 2011-06-23
Also published as: NO337632B1; NO20093553A1

Abstract

Apparatus for the manufacture of bitumen particles, characterised in that the apparatus comprises a tool for forming of the bitumen particles, an appliance for wetting the surfaces of the tool that form and come into contact with the bitumen, with a fluid that wets the tool but does not wet the bitumen, and an appliance to regulate or hold the temperature of the fluid.

Description

Bitumen particles

Field of the invention

The present invention relates to bodies of bitumen. More specifically, the invention relates to equipment for manufacture of bitumen particles, methods for manufacture of bitumen particles and methods for storage, transportation and the laying out of matter comprising bitumen particles.

Background to the invention and prior art

Bitumen is the heaviest constituent of crude oil and thereby a distillation residual product from the refining. Bitumen, sometimes erroneously called asphalt, can be found in many natural and synthetic compositions. Bitumen is a very viscous, pitch like liquid, which hardens at low temperature. At the temperatures below Fraas breaking point, as determined by EN 12593, cracks are formed in the deformation of bitumen.

A possible application of bitumen is as a joint filler between, and possibly below, paving stones, tiles, blocks and other materials. This is described in Norwegian patent application NO 2009 1508 as a bitumen containing joint filler is cooled down and kept chilled in the placing of the joint filler. In the Japanese patent publication JP 1 1152477 the manufacture of bitumen bodies, with alcohol as the cooling fluid, is described. In particular melted bitumen at a temperature of typically 120-200 °C is dripped or lowered down into a stirred, cooling alcohol solution. To reduce the sticking characteristics an anti-sticking agent is added to the bitumen particles. According to the example in the Japanese patent the manufactured bitumen particles have a relatively variable shape and size.

There is a need for a technology that simplifies the manufacture of particles of bitumen and the transportation and the laying of bitumen-containing joint filler. Summary of the invention

The above mentioned need is met in that the present invention provides an apparatus for the manufacture of bitumen particles, a method for the

manufacture of bitumen particles and a method for storage, transportation and/or laying off and/or sorting/sieving of bitumen particles or a joint filler comprising bitumen particles.

In particular, the invention provides an apparatus for manufacture of bitumen particles characterised in that the apparatus comprises a tool for forming of the bitumen particles, an appliance for wetting the surfaces of the tool that form and come in to contact with the bitumen with a fluid that wets the tool but does not wet the bitumen, and a device to control or hold the temperature of the fluid. It is an advantage if the fluid shall both wet and cool the surfaces of the tool that form and come into contact with the bitumen.

It has surprisingly been found that the bitumen particles can thereby be formed without sticking to the tool or to each other. A fluid that does not wet the bitumen but wets the surfaces of the tool that form and come into contact with the bitumen, means that the fluid has a contact angle for a drop of the fluid on the bitumen greater than 90° while the contact angle for a drop of the fluid on the forming surfaces of the tool is less than 90°. If the fluid is water the tool is hydrophilic whilst the bitumen is hydrophobic. The contact angle is the angle between the interphase of the fluid/solid surface and the tangent where the drop meets the surface around the circumference of the drop. A more detailed explanation can be found on the internet pages

http://en.wikipedia.org/wiki/Contact_angle and

http://aluminium. matter.org. uk/content html/ENG/default.asp?catid=107&pageid =2144416260.

It is advantageous if the apparatus comprises an appliance for the wetting chosen from a fluid container where the forming tool is at least partially submersed in the fluid, and a hosing device. It is an advantage if the forming tool is partially submerged in water and/or hosed down with water because water is not poisonous, not dangerous, cheap, easily available and does not dissolve bitumen. It is most advantageous if the surfaces of the tool that form and create and make the bitumen particle are chilled and moistened by water that is hosed onto them, with the tool being arranged above a water container where the particles that are formed drop down into the cold water. Alternatively, other fluids such as glycol or alcohol can be used but many such other fluids lead to disadvantages with respect to the environment and health and have a dissolving effect on the bitumen. The fluid can also be a mixture of fluids, such as water mixed with glycol, so that the fluid temperature can be held lower than 0 °C. It is possible to feed the tool from below if the bitumen density is lower than the fluid density, as is normally the case with warm bitumen and cold water. When the densities are the other way around, hot bitumen, or bitumen with a content of heavy material will always sink down in the fluid.

It is advantageous if the forming tool is manufactured from anodised aluminium and is in the shape of two opposite facing wheels with half ball-formed recesses distributed around the outer circumference of the wheel surfaces, the wheels are set up to rotate opposite directions and in synchrony and led together, during the supply of bitumen from a feeding part to the recesses, for the formation of bitumen balls, and furthermore it is advantageous if the tool further comprises an elastic suspension for at least one of the rollers so that the roller can retract and let large lumps pass, and it is an advantage if the tool in addition comprises a blowing device directed towards the wheel surfaces for the blowing of air, preferably cold air, to prevent that excess water leads to production failures. The forming tool, made from aluminium, conducts heat well, which is an advantage if the bitumen is warmer than the fluid and the tool before the forming, as the bitumen thereby stiffens a bit and lets go of the tool more easily. The forming tool can, in principle, have any known form for the formation of particles, balls or bodies, such as tools based on cutting, stamping and/or press-forming and other known methods, as the above mentioned is only a preferred form of many possibilities. The tool surfaces that come into contact with the bitumen are advantageously of a material with the best possible wetting of water to let go of the bitumen as easily as possible after the forming.

Anodised or oxidised metal, such as aluminium, steel or other metals are suitable. Polymer materials, composite materials and ceramic materials, such as POM, PVDF, PA, polyolefins and zirconium oxides can also be used for the forming tool, but wetting characteristics, strength and durability at the operating temperature and heat conduction characteristics must be considered. It is most advantageous to combine partial submersion of the tool (the forming tool), i.e. of the lower part of the wheel, with hosing down of the wheels with water above the waterline and blowing of air, with the blowing and hosing down being most advantageous if carried out from both the inside and outside of the tool, as this gives the best control of the manufacture and the highest production rate combined with the lowest rate of production faults. In particular, the tool advantageously comprises channels with nozzles out to the bitumen particle forms, for hosing down with water and/or blowing with air, which ensures that the bitumen particles easily come loose from the tool. Thereby, the bitumen particles have a concave surface shape innermost in the form of the forming surface of the tool.

The invention also provides a method for the manufacture of bitumen particles, characterised in that the particles are formed in a forming tool that is being moistened by a fluid which does not moisten the bitumen but moistens the surfaces of the tool that form and come into contact with the bitumen and the temperature of the fluid is controlled or held at a desired level. It is an

advantage if the fluid is water, for the same reasons as those mentioned previously, preferably at a temperature of 0-10 °C, more preferably 0-5 °C. It is an advantage if the method comprises hosing down with water, whether the hosing is only with the help of the hosing or also by partially submersing the tool in water, as the hosing ensures that cold, hard particles of bitumen do not come back to the warm inlet side of the tool and disturb the production. Alternative fluids are also as previously mentioned. Air, preferably cold air, i.e. air at 0-15 °C, more preferably 0-5 °C is blown at the same time onto the surfaces of the tool to regulate the wetting. It is most advantageous to combine partial submersion of the tool (the forming tool), i.e. the lower part of the wheels, with hosing of the wheels with water above the waterline and blowing of air, as this gives the best control of the manufacturing process and the highest production rate combined with the lowest failure rate.

The invention also provides a method for storage, transportation and/or laying of and/or sorting/sieving of bitumen particles or joint fillers comprising bitumen particles, characterised in that the particles or the joint filler are held in a liquid that does not wet bitumen. It is an advantage if the fluid is water, for the same reasons as those mentioned previously, preferably at a temperature of

0-10 °C, more preferably 0-5 °C. Alternative fluids are also as previously mentioned.

Meant by the description bitumen particles are bodies of bitumen in any shape, but preferably of a moderate, or small, size (typically, but not necessarily below 25, 20, 15 or 10 mm in diameter) and preferably of a uniform shape. Figures

The invention is illustrated with the help of two figures, where

Figure 1 illustrates an apparatus according to the present invention, and

Figure 2 illustrates the forming tool of the apparatus in Fig. 1 . Detailed description

Reference is made to Fig. 1 which illustrates an apparatus 1 according to the invention. A forming tool 2 can also be seen. The apparatus comprises a feeding device 3 of any kind suited to feeding, that is delivery of bitumen to the forming tool. More specifically, the reference numerical of Fig. 1 are as follows: 1 . Warm bitumen

2. Two cogged wheels to synchronise the rotating forms 3. Two rotating, wet and cold forms to shape and cool the bitumen particles

4. Cut up pipe for cold air that shall blow excess water out of the forms

5. Cut up pipe for cold water that shall moisten, cool and flush out possible remains from the forms

6. Bitumen particles that are cooled to a firmer consistency

7. Pump for pumping out bitumen particles together with fluid (water)

8. Storage

9. Storage mounted on a gliding rail against a spring so that the form can be retracted so that the forms have good contact, and hard particles can be let past.

10. Two shafts

1 1. Cold fluid (water)

12. Container for the fluid (water)

13. Pipe/hose for bitumen particles and fluid (water) that shall sieving and storage with or without fluid (water)

14. Recycled fluid (water) and refilling of cold water

15. Hole for flushing out of particles from the inside, according to need.

The feeding device is not illustrated, but can be for example a hose pump, but other pumps, such as a positive displacement pump of nearly any kind, can be used. A free fall from an above lying tank, through a regulation valve or the like can also be used. Similarly, the feeding device can be an extruding machine. Motors and a pump for circulation of fluid are also parts of the illustrated apparatus, but do not represent obligatory features. It is not necessary to cool or heat the bitumen, but one must choose a bitumen quality with a Fraas breaking point lower than the ambient temperature so that the bitumen can be easily formed into shape. For example, bitumen grade 70/100, which has a Fraas breaking point according to EN 12593 of around -10 °C, is good to use. However, the apparatus can advantageously contain heating and cooling appliances so that it is easier to deliver the bitumen with a suitable viscosity from the feeding device at an elevated temperature, and be cooled down in the fluid so that the surface stiffens somewhat. Thus, the feeding device contains a heating appliance, or ready heated bitumen is delivered to the feeding device. This can lead to considerably increased production. In the embodiment illustrated water containing pieces of ice was used as the fluid with very good results. The apparatus can, in its simplest form, only comprise the forming tool itself completely or preferably only partially, contained in a fluid container or subjected to a flow of fluid, for example, in the form of engraved wheels that are facing each other and driven by a crank handle.

Reference is made to Fig. 2 that shows the forming tool 2 of the apparatus illustrated in Fig. 1. In particular, the forming tool is two wheels or rollers facing each other with a half ball-formed engraved surface pattern, arranged for mounting and connecting to a drive device such as a motor. In the figure, the forming tool is out of scale and orientation, and is not illustrated as partly submersed in or flushed by a fluid, for reasons of clarity. The rotation of the two wheels or rollers is in opposite direction, but the rotation is otherwise

synchronous in speed between the wheels, and advantageously carefully adjusted to the delivery rate of the feeding device. Bitumen balls are formed when the bitumen is fed between and past the opposite facing rotating rollers, bitumen balls fall down into the fluid underneath the rollers, from where the bitumen balls, preferably cooled down in a cold fluid such as cold water, can be pumped to storage and be transported on.

The produced bitumen balls have been shown in practical tests to be able to be stored, be transported and be delivered and pumped out as contained in a fluid, advantageously in water, for example, in and from a dairy vehicle with a pump. It is an advantage if the water contains pieces of ice or is held at a temperature in the region of 0-10 °C, more preferentially 0-5 °C as this prevents clumping better and simplifies pumping and delivery. For storage, transportation and laying, the fluid temperature can advantageously be down toward the Fraas breaking point temperature such that clumping too soon and brittle crushing are in practice eliminated as sources of production faults. After laying, the water without significant pollution, will run away or evaporate, while the bitumen particles will stick together naturally. However, it is possible to use water at ambient temperature, but the bitumen ought to have a Fraas breaking point that does not lie too low below a such higher water temperature, for example, not more than 20 °C, more preferably not more than 10-5 °C lower than the water temperature. In cold climates it would be an advantage if a softer bitumen is used than in temperate climates, while in temperate climates it will be an advantage to use a softer bitumen than in hot climates, so that hardness and sticking together and self-repairing characteristics are adapted to the location for the application. Consequently stiffer bitumen should be used at increasing temperatures. Examples of typical quality standards for applicable bitumen, based on intervals for penetration numbers for normal bitumen (=penetration grades)(not polymer modified) or such that it is also applicable (oxidised bitumen = blown/oxidised bitumen) with associated requirements for the highest Fraas breaking point, with the stiffest grades given first being as follows: 35/50 - 5 °C, 50/70 -8 °C, 70/100 -10 °C, 100/150 -12 °C, 250/330 -15 °C and 330/430 - 18 °C. The values are taken from the Norwegian Public Roads Administration Handbook 018 (The penetration number is 1/10 mm indentation by a needle at 25 °C)

http://www.vegvesen.no/binarv?id=198239

For further information reference is made to the international standard EN 1426:2007.

The uppermost part of, for example, a groove can contain harder bitumen than the main part of the groove, for increased hardness and durability. Such harder bitumen is easier to transport and lay, but can require heating to form an even covering if the surrounding temperature is sufficiently high. It is an advantage if the forming of such harder bitumen is carried out at a higher temperature than for softer bitumen. The bitumen is regarded to be mouldable at temperatures above the Fraas breaking point temperature, such that during the forming itself, the average temperature must not fall below the Fraas breaking point temperature. The bitumen particles can be formed while the bitumen is cooled down to a temperature below the Fraas breaking point, but the forming must, in the main, be completed before said temperature becomes too low, which represents a preferred embodiment of the invention.

The apparatus and the methods according to the invention can encompass features which are described or illustrated here in any operative applicable combination, said combinations being a part of the invention.

Claims

Claims 1.

Apparatus for manufacture of bitumen particles, characterised in that the apparatus comprises a tool for the forming of the bitumen particles, an appliance for wetting the surfaces of the tool that form and come into contact with the bitumen with a fluid that wets the tool but does not wet the bitumen, and an appliance to control or hold the temperature of the fluid.

2.

Apparatus according to claim 1, characterised in that the appliance for wetting is chosen from a fluid container where the forming tool is at least partially submersed in the fluid and a hosing device.

3.

Apparatus according to claim ^characterised in that the forming tool is manufactured from anodised aluminium and is in the shape of two facing wheels with half ball-formed recesses distributed around the outer

circumferences of the wheel surfaces, the wheels are set up to rotate in opposite directions and in synchrony and come together during the supply of bitumen from a feeding part to the recesses for the formation of bitumen balls, and furthermore the tool can advantageously comprise an elastic suspension for at least one of the rollers so that the roller can retract and let larger clumps pass, and in addition the tool advantageously comprises a blowing device directed towards the wheel surfaces for the blowing of air, preferably cold air, to prevent that excess water leads to production failures.

4.

Apparatus according to one of the claims 1-3, characterised in that the forming tool is continuously flushed with water at 0-10 °C. Method for manufacture of bitumen particles, characterised in that the particles are formed in a forming tool that is made wet by a fluid that does not moisten the bitumen but wets the surfaces of the tool that form and come into contact with the bitumen and the temperature of the fluid is controlled or held at a desired level.

6.

Method according to claim 5, characterised in that the fluid is flushed continuously during operation and the fluid is water; and air, preferably cold air, is blown at the surfaces of the tool at the same time to regulate the wetting.

7.

Method according to claim 6, characterised in that the fluid is water at a temperature of 0-10 °C, more preferably 0-5 °C.

8.

Method for storage, transportation and/or laying and/or sorting/sieving of bitumen particles or joint fillers containing bitumen particles,

characterised in that the particles or the joint filler is contained in a fluid that does not wet the bitumen.

9.

Method according to claim 8, characterised in that the fluid is water.

10.

Method according to claim 9, characterised in that the fluid is water at a temperature of 0-10 °C, more preferably 0-5 °C.