July 23, 2008

Recycling Bitumen

Recycling Asphalt for Economic Advantage
Recycling is becoming part of the production process in many industries and the asphalt sector is no exception. The advantages of reprocessing reclaimed asphalt are not just economic in an increasingly price sensitive market, the process also preserves a valuable natural resource.

Prior to the asphalt planings being used in the recycling process, they have to be broken down to an acceptable size without reducing the original stone content. Benninghoven has developed recycling granulator to break asphalt blocks and plannings to a recyclable size without reducing the original stone content thereby creating minimum fines, all at the most economic production level. The planings are fed into a single shaft granulator where they are broken down and fed up to a single deck screen.

Materials go into the feed hopper and are forced in the single shaft granulator by oscillating hydraulic rams. The granulated material is then conveyed to the single deck screens after passing a magnetic belt detector, which removes any metal in the feed. The single deck screen separates the ready to size material for stockpiling, the oversize material is passed through the secondary double shafted granulator. This double shaft granulator is equipped with an adjustable setting to enable final product grading. The final material is produced to meet acceptable gradings that enables further processing to give maximum economical results.

Cold recycling

Reclaimed asphalt planings can be added in quantities of up to 25% direct into the asphalt plant paddle mixer, where it is mixed homogenously with virgin aggregates. This method is in common use throughout the UK and Ireland for processing small percentages of RAP.

A further innovative add on system, which can result in up to 35% asphalt planings being processed, is by using the existing plant dryer. Here the planings are introduced into the discharge end of the dryer via a slinger conveyor to mix with new material in the drum. Heat transfer continues during the materials movement to the plant mixing section, where it bypasses the screen and is introduced to the mixer through the weigh section.

Hot recycling

Although hot asphalt recycling has become an accepted practice throughout Europe, it is only now that operators are striving to keep down costs, maximising their operating efficiency together with projecting a more sustainable image, that they have started to embrace this new technology. Where larger quantities of reclaimed asphalt planings need to be processed - above 35% and up to 100% - then hot recycling is the only option. For many years Benninghoven have been developing new and improved methods of processing these waste asphalt materials. Their designs have made possible this high percentage of RAP recovery and provided operators with equipment, which helps preserving valuable natural resources.

A feature of the hot recycling plant is that the drum is mounted at high level to facilitate the movement of reclaimed materials into the existing asphalt plant process. At the heart of the system is a separate 11 m long large volume uniflow drum, which both dries and heats the recycled asphalt. The design of the drum internals ensures the burner flame makes no contact with the moving reclaimed material inside the drum. In the heat exchange zone, material travels smoothly through the cross section of the drum, which results in optimum heating combined with economic use of the burner and low exhaust gas temperatures.

In the next hot gas zone the materials are agitated, so protecting the drum skin from thermal overheating. The combustion zone of the hot RAP drum is fitted with special finger lifters, which vibrate during the production process to prevent clogging of the material during the heating process. The drum is fully lagged to minimise radiation loss and insulated with special zinc coated steel. Drive is by four 22 kW geared motors with friction drive.

A special compact, multi-fuel burner, which can burn a variety of fuels, including oil, natural gas, liquefied gas and coal, is used and is fitted with its own internal axial fan which provides the total air required for the combustion process. Frequency inverter control of the main blower fan provides the benefits of a perfect air/fuel ratio throughout the burner's operating range, thereby obtaining optimum running efficiency.

Hot recycled materials are discharged from the drum through an enclosed conveyor then by chute into a holding buffer silo. This is fully insulated and clad to maintain the temperature of the materials. From here it is batch weighed to the plant mixer as required. A feature of hot recycling systems is that the drum is mounted at a high level to facilitate the movement of the reclaimed materials into an existing plant process.

In recent months, Benninghoven have secured a major order for a state-of-the-art, high level, hot recycling plant for a site at West Drayton, with installation to start in May 2008. This will be the first plant of its type in the UK.

Mobile Bitumen Plants

Mobile Asphalt Plants ready to take off
Demand for more productive methods of reconstructing runways is increasing the need for high capacity, mobile asphalt plants.

Engineers at Colas are preparing to take the firm's Ermont asphalt plant out on the road again, for supplying a programme of runway resurfacing projects at UK airports. The paving materials and contracting company is anticipating a busy 2008 in the airfields sector, following project successes over the past two years using innovative paving materials and its Ermont plant. Demand for similar work is gaining momentum.
Runways and taxiways at a number of UK airports are likely to be resurfaced by Colas this year, using airfield paving technology the company has introduced from France. The materials allow higher levels of asphalt laying productivity compared to traditional UK techniques and so have raised the need for high output plants such as the company's Ermont TSM225.

Over the past two years, the mobile plant has been used on the Shetland Isles and Tiree in the Inner Hebrides; projects which have shown materials developed to the French BBA (Beton Bitumeux Aeronautique) standard can be laid quicker than the Marshall Asphalt traditionally used in the UK. Airport operators are under pressure to maximise the availability of their runways and the demand is for greater durability, which brings a long term benefit for operators tghrough reduced frequency of maintenance.

"There has been a surge in interest from UK airport operators, in European materials, due to the now proven possibilities for reducing project time and extending the life of their runways," says Colas's airfields division business manager Carl Fergusson. "The mobile Ermont plant is just as suitable for producing large quantities of conventional asphalt for airfield and road surfacing projects, but the BBA materials have made very high outputs possible over a given time. This makes it economically viable to use the Ermont plant on airfield paving projects."
Colas's mobile plant, comprising material silos, mixing drum and generators, is transported on 11 trailers and, according to Fergusson, is the only one of its kind in the UK with a production capacity of 225 tph. It is also available for hire and further in its favour, the plant is connected up still standing on its trailers and very rarely requires construction of foundations before it is set up. "This takes only two weeks, from arrival to commissioning, so the plant is a huge help in planning terms and for getting to sites and starting work quickly," Fergusson says.

Colas first introduced BBA asphalt to the UK with the aid of its Ermont plant for the extension and resurfacing of Sumburgh Airport's main runway for operator HIAL (Highland & Islands Airports Ltd). This was no mean feat because Colas first had to demonstrate that the BBA asphalt mix would work when produced with the particular aggregates and bitumen to be used.

The BBA specification is more flexible than the Marshall Asphalt mix recipe approach; instead specifying materials to their required end performance. The French specification, however, requires aggregates and bitumen with particular high spec characteristics. Every BBA mix has to be designed to its specific constituents and then tested to prove the mix of ingredients will provide the necessary performance.

"We carried out the mix development work with help and advice from our CST (Campus for Science & Techniques) technical centre in France, with aggregates won on site at Sumburgh and bitumen from Nynas' refinery in Dundee," Fergusson says. "Mix design tests proved the required stiffness and other important performance parameters and the surfacing, once under way, demonstrated how much easier the BBA material was to manufacture and lay.

"We needed the Ermont plant because with the BBA mix, we could produce 200 tph and lay 200 m of surface course over the full 45m width of the runway in one shift. This was without cause for concern over correct compaction and air voids which can be the case with Marshall Asphalt."

That was in 2006 and was followed by HIAL asking Colas for a near repeat for resurfacing Tiree Airport's main runway last year. The Tiree work was similar, although this time with high spec aggregate from southern Ireland and an even greater test of planning and logistics to get materials and the Ermont plant to site on chartered and scheduled ferries.

All went well, according to Fergusson. With good planning and the Ermont plant's large bitumen and fuel storage sufficient to keep it running continuously through a 12 hour shift, Colas was able to lay more than 300 m of the 100 mm deep asphalt overlay between scheduled flights. The surfacing was finished during 21 working days in September 2007 and since then, representatives from UK airport operators including BAA have visited Tiree to inspect the results. There could be a lot of work in future for high output plants at UK airports.

Hot Asphalt Storage

BG Europa of Wickhambrook has recently installed an FMA Ullrich Hot Asphalt storage extension to existing Sherwin silos at the Lafarge Ashbury Depot in Manchester.

A two compartment SE120/2 with a total storage capacity of 120 tons split equally between the two bins has been installed to the end of the three existing silos. A 37Kw frequency controlled winch along with a complete track replacement completed the installation.

The speed of the skip is controlled through an invertor to ensure rapid transit along the track and gentle arrival at the charging and discharge points with rope stretch accounted for by the continual reset of the skip reference point on each journey. A tacho -generator ensures that skip positioning during operation is accurate to 10mm; as this system does not require limit switches at the skip charging and discharging points, maintenance issues are therefore reduced.

The new bottom discharge skip has a capacity of 2000kg and is lined with stainless steel to promote clean operation. The skip system can operate at 140 tph with a 52 second cycle time to the furthest bin which represents a significant improvement in skip performance.

The FMA Ullrich UCC5 skip controls feature an energy saving mode which matches skip performance to batch plant output. The speed of the skip is automatically controlled to ensure that it returns to the mixer at the time required for batch discharge, eliminating excessive power usage by unnecessarily accelerating the skip.

As the low level Parker Batch Tower at Ashbury does not allow vehicles to be loaded directly it was imperative that the project was completed during the programmed shutdown period. BG Europa successfully ensured full plant production was achieved on the programmed date with minimal disruption to the established Lafarge customer base.

Joan Hughes, Manager of the Ashbury depot, commented, "We were very pleased at how safe the work was completed onsite. During and after commissioning we had very few teething problems. The new skip system has improved our production rate, and reduced down time. The Hot Storage has given us more flexibility so that we meet our customer needs better."

The Ashbury project represents the first BG Europa - Ullrich hot storage installation for Lafarge in 2008. A second installation is planned for the Lafarge Ackworth depot where an S200/4 II will provide 200 tons of storage in a total of four bins; two at 53 tons and two at 47 tons. The S200/4 II parallel storage silo offers a versatile compact storage solution where space and site layout can prelude alternative arrangements. The Ackworth S200/4 will be the third such system operated by Lafarge with the others at Mountsorrel and Hafod Quarries. BG Europa of Wickhambrook has recently installed an extension to existing Sherwin silos at the Lafarge Ashbury Depot in Manchester.

A two compartment SE120/2 with a total storage capacity of 120 tons split equally between the two bins has been installed to the end of the three existing silos. A 37Kw frequency controlled winch along with a complete track replacement completed the installation.

The speed of the skip is controlled through an invertor to ensure rapid transit along the track and gentle arrival at the charging and discharge points with rope stretch accounted for by the continual reset of the skip reference point on each journey. A tacho -generator ensures that skip positioning during operation is accurate to 10mm; as this system does not require limit switches at the skip charging and discharging points, maintenance issues are therefore reduced.

The new bottom discharge skip has a capacity of 2000kg and is lined with stainless steel to promote clean operation. The skip system can operate at 140 tph with a 52 second cycle time to the furthest bin which represents a significant improvement in skip performance.

The FMA Ullrich UCC5 skip controls feature an energy saving mode which matches skip performance to batch plant output. The speed of the skip is automatically controlled to ensure that it returns to the mixer at the time required for batch discharge, eliminating excessive power usage by unnecessarily accelerating the skip.

As the low level Parker Batch Tower at Ashbury does not allow vehicles to be loaded directly it was imperative that the project was completed during the programmed shutdown period. BG Europa successfully ensured full plant production was achieved on the programmed date with minimal disruption to the established Lafarge customer base.

Joan Hughes, Manager of the Ashbury depot, commented, "We were very pleased at how safe the work was completed onsite. During and after commissioning we had very few teething problems. The new skip system has improved our production rate, and reduced down time. The Hot Storage has given us more flexibility so that we meet our customer needs better."

The Ashbury project represents the first BG Europa - Ullrich hot storage installation for Lafarge in 2008. A second installation is planned for the Lafarge Ackworth depot where an S200/4 II will provide 200 tons of storage in a total of four bins; two at 53 tons and two at 47 tons. The S200/4 II parallel storage silo offers a versatile compact storage solution where space and site layout can prelude alternative arrangements. The Ackworth S200/4 will be the third such system operated by Lafarge with the others at Mountsorrel and Hafod Quarries.

July 11, 2008

Total to Tap Indian Bitumen Market

International oil and gas giant Total of France on Wednesday announced the setting up of a joint venture with Vinergy International for manufacturing and marketing world-class value added bitumen products for India. The joint venture will witness an investment of Rs. 100 crore during the next three years.

Making this announcement here, Total’s India Country Chairman, Christian Chammas, told newsmen that the 50:50 joint venture, Total Vinergy Bitumen India, had already commissioned a plant at Jodhpur in Rajasthan with an investment of about Rs. 25 crore and was in the process of selecting sites for setting up units in East, South and West of the country.

Vinergy Managing Director, Mukul Agarwal, said the four plants would have a bitumen manufacturing capacity of three lakh tonnes a year. Bitumen is used in the construction of roads and highways.

“The quality of bitumen being produced at these plants would be much higher than what was available. We are going to introduce the latest technology that would ensure that the life of roads would increase by 3-4 years,” Mr. Chammas said.

The joint venture will provide high quality bitumen and modified bituminous products to the road construction industry, something that is now not available. Mr. Aggarwal said they planned to commission one plant a year adding that the country had a demand of 4.1 million tonnes of bitumen as against a supply of 3.7 million tonnes. The joint venture is targeting $50 million in sales in the first year of operation.

July 6, 2008

Safety in handling bitumen

This arricle was reporduced from BBC for the sake of safety in handling bitumen

15-year-old boy was engulfed in flames and suffered a serious ankle injury when a metal drum exploded.

The teenager was using a grinder to cut the top off the 45 gallon drum, which contained a residue of bitumen, when a spark set off an explosion.

He suffered burns to his face and right hand and the blade from the grinder sliced into his ankle.

The boy was helping out at his father's fencing business in Brentwood, Essex, when the accident happened.

When Essex Fire and Rescue Service arrived, workers at the site had already stripped off the boy's burning clothes and put out the flames.

One of the first fire fighters on the scene, sub officer Neil Young said: "When we arrived, the boy was in a very bad way.

"Every exposed part of his body had been burnt. We put dressing on his burns and bandaged his ankle while waiting for paramedics to arrive."

The teenager was taken to the burns unit at Broomfield Hospital, Chelmsford. His injuries are not thought to be life-threatening.

Bitumen Standards


This article attempts to have a re-look at a comparitive study of bitumen standards acorss Asia and the key differences in evaluation to suit the local needs.

Most of the bitumen producing nations including Saudi Arabia, Thailand, Singapore, Iran, Malaysia and Newzeland in Asia uses the penetration test (ASTM D-5) ( as specified by TNZ/M/1 in Newzeland's standards) as against their Australian counterparts who uses the viscosity of the bitumen to define the grades of bitumen. This has given rise to difference in manufacturing standards between the rest of it's neighbors.

Grades as per D-5, carried out under laboratory conditions at 25 deg C to determine the depth that a weighted needle skins into bitumen specimen over 5 seconds. Thus the higher the grade, the softer the bitumen. It is measured in tenths of a millimeter. 60/70 grade has a depth of penetration between 6 & 7 millimeters.

This test, although look crude, is still internationally used as it serves as a reference point to compare the property of the bitumen at higher temperatures and it’s consistency with regards to Softening point and viscosity.

with reference to it’s physical characteristics, simply at the ambient temperature, are graded as

180/200 Softer Sealing
130/150 Soft Sealing
80/100 Hard Hot mix Asphalt binder, sealing
60/70 Harder Hot mix Asphalt binder

Most of the nations like Newzeland has one or more than one refinery , which cannot cater to their local demand, the additional requirements for the road construction are being imported.

Australian Bitumen

Australia uses the viscosity of the bitumen to define the grades of bitumen. This is in total contrast with the simple and internationally followed standard of Penetration test per ASTM D-5 .

To comply with AS 2008, the viscosity of the bitumen is tested at 60 deg C to define the four grade of bitumen used for pavement construction.


Grade Viscosity International Character Application
Class 50 40-60 No Equivalent Softer Sealing
Class 170 140-200 80/100 Soft Sealing
Class 320 260-380 60/70 Hard Hot mix Asphalt , sealing
Class 600 500-700 40/50 Harder Hot mix Asphalt

Viscosity is basically a measure of consistency and higher the viscosity , the harder the bitumen gets.


The advantages of using Viscosity over the Penetration tests are

• Viscosity is independent of the test system and the sample size.
• At 60 deg C, the testing range is close the pavement temperature
• Comparative studies of viscosity over a range from 60-150 deg C yields the bitumen’s temperature susceptibility.

Resources
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