Panorama Editorials Archive

Editorials Archive

Less risk - More benefit: Mobile loading solutions


 Ely, April 2011 – In order to cover great distances with general dry bulk cargo, both barge and rail transportation represent the least polluting and most economical solution. However road haulage is very attractive in terms of flexibility and low capital cost. Trucks may be easily loaded and simply tip their load off at the point of discharge.

The difference springs to mind when comparing trucks to barges: While one truck may carry 30 tons, one barge may carry 150 to 200 trucks (5,000 tons) and both the truck and the barge only require one driver. That is why in the dry bulk sector often a single self-propelled barge is the only viable option for higher tonnages of the same material. Energy consumption and required manpower favour barges, still the need for loading and discharging facilities has to be considered. Where there are no existing facilities the cost of building new load out and discharge plant can make both barge and rail transportation uneconomic with a relatively high investment risk. Mobile equipment might therefore be the best solution with low capital risk and high operational flexibility. Especially when it comes to transporting minerals, coal or ore from quarry to processing plants, mobile handling equipment is first choice.

Mobile Ship And Train Loading

A good example is the Basalt Company’s quarry in Russia. The B&W (Aumund Group) StormajorTM is operated there as a mobile barge loader. It comprises an integral SamsonTM surface feeder with a radial loading boom, both mounted on an integrated fully mobile chassis with pneumatic tyres for easy movement as a single and fully autonomous machine. The cantilevered boom of the StormajorTM is a major advantage with sufficient outreach to load barges moored off shore. The only civil works that are required is a hard standing for the StormajorTM plus some mooring dolphins for the barge.

Material may be received either from local stockpile using a loading shovel to feed the StormajorTM or with the use of a small truck ramp vehicles and dump trucks may discharge directly to the integral Samson feeder eliminating double handling.

In the Russian project the aggregates are shipped from Sheleki (south of Murmansk) down to St. Petersburg and Moscow with 5,000 DWT barges since neither city has any natural stone available locally.

In addition to barge loading, the B&W equipment may also be applied to railcar loading. Often seen in ports and terminals, bulk material has to be loaded onto trains for inland transportation. The risk of overloading the railcars is eliminated through integral weighing equipment. This way only the desired net weight is loaded onto each railcar thus eliminating the costs and delays associated with either over or under loading. Knowing the load on the weigh idler, the angle of the boom and the belt speed, the instantaneous handling rate, may be computed and the total integrated using a specially designed instrument arranged such that the required railcar load may be simply entered on a keypad and the equipment will ensure only this weight of material is loaded to within an accuracy of plus or minus 1.5 per cent.

Another important aspect is the full mobility of the StormajorTM. It can move along the rake of wagons eliminating the need for a locomotive permanently employed for shunting. It only requires a suitable rail siding.

Train Unloading

In addition to the SamsonTM surface feeder as employed with the StormajorTM, the apron-belt feeder concept may also be utilised for the discharge of railcars. The first such application utilising the SamsonTM feeder principle for under rail installation was installed at Cementos Balboa in Spain. The Samson receives material directly from hopper bottom railcars, requiring the minimum excavation depth and thanks to the raised discharge, provides a simplified transfer to the ongoing belt conveyor equipment.

The SamsonTM body and belt are actually wider than the typical railcar outlet and therefore the material flows freely into the Samson body with the absolute minimum of free fall, reducing the level of particulate separation and material terminal velocity. Therefore the velocity of the displaced air is significantly reduced, thereby significantly reducing dust generation requiring less dust extraction in even the most environmentally sensitive location.

Mobile Shiploading Solutions

Another good example of mobile bulk handling comes from Greenland. A mobile shiploader is operating in Fiskefjord harbour exporting olivine rock. Olivine is found in the volcanic rocks of Greenland where there are substantial deposits. It is an important mineral used in steel production mainly as a refractory raw material and slag conditioner.

The facility is operated on behalf of Minelco (part of the LKAB group headquartered in Sweden) and includes a mining operation plus crushing and screening station located close to the new deep water jetty with a planned annual output of 2 million tons. The European steel industry is a self-evident market for olivine, which is an important additive in LKAB’s blast furnace pellets. The first vessel sailed from Greenland on December 2nd 2005, bound for Amsterdam using a temporary system provided by B&W as a short term solution.

From the crusher stockpile the olivine is taken by loading shovel to the shiploader utilising a SamsonTM 1600 series mobile feeder to control the loading rate to a design capacity of 2,000 tons per hour. The jetty is simply constructed with in-filled rock; fenders and mooring dolphins are provided for berthing vessels typically up to 50,000 DWT. This is an excellent example of the application of the professional mobile shiploader in a location where fixed or rail mounted equipment would be entirely inappropriate.

The mobile solution eliminates the need for permanent port infrastructure or even any concrete quay surface or foundations, offering the operator the flexibility to establish an export facility with minimum cost and fast track availability.

For this application the new shiploader was supplied with a boom length of 45 metres and a belt width of 1400 mm to achieve the required loading rate. In addition, an on-board diesel generator provides electric power for the equipment making the shiploader fully autonomous. To make things more demanding, operating temperature varied from minus 30 to plus 10 degree Celsius, thus creating flow problems caused by frozen stockpiles.

Anyway, at this latitude daylight hours are limited in the autumn months and in the winter the port becomes iced up, limiting the available working period. Building any fixed port infrastructure under these conditions would be uneconomic and impractical.

Whilst the olivine was transported from the local stockpile by loading shovel right from the start, B&W offers its Link Conveyor to transfer the material more economically over larger distances from the quarry or the crusher to the ship loading facilities.

Low Capital Risk

In today’s rapidly changing international market the ability to react quickly to market volatility and take advantage of short-term market positions is essential if operators are to maximise profitability and return on capital invested.

The mobile solution offers the performance - both in terms of loading rates and environmental qualities - of a fixed installation with the added bonus of complete flexibility and ease of operation on existing berths without the need for dedicated port infrastructure or expensive permanent civil works.

The Truck-to-Ship concept pioneered by B&W (Aumund Group) opens up new possibilities for existing ports, eliminating the need for storage at port and the associated double handling. It simplifies investment decisions allowing the port operator or shipper to take advantage of smaller, but potentially lucrative cargo volumes and short term contracts. That would certainly not be viable with the high investment and long lead times associated with a conventional fixed installation.

Furthermore, for large, fixed installations the local permitting process and inevitable environmental impact study requirements may often be waived for mobile plant, thereby not only simplifying the process of bringing a new facility into the port but also speeding up the effective project lead time, from identifying the potential bulk export opportunity to loading the first vessel.

Mobile solutions are not tied to one berth, one harbour or even one port and may easily be moved on demand.

Dust Control

Handling dusty materials discharged by grab can be a real environmental hazard if not properly managed using a dust controlled grab hopper by Aumund. The Eco-Hopper comprises an inner and outer hopper with flex-baffles in between allowing the material to flow freely into the hopper and constraining any reverse flow to minimise dust generation. Air displaced by the falling material is evacuated from the hopper’s inner bowl by reverse jet dust filters mounted around the hopper periphery between the inner and outer garners.

The Eco-Hoppers as illustrated may discharge direct to quayside belt conveyors using the Aumund control gate. However, the hopper may discharge directly to trucks using the Aumund dust controlled loading chute, similar to the unit previously illustrated for barge loading.

In conclusion, where fixed loading facilities cannot be economically justified, the B&W Mechanical Handling division of the Aumund Group has unique solutions based on highly developed, mobile designs able to achieve the same level of performance and environmental protection but with complete flexibility in operation.

Innovative designs based on proven engineering skills deliver performance with reliability, whilst meeting the requirements of the customer first and foremost.