There can be many challenges associated with loading crushed stone onto a boat. Lack of space, inflexible shippers that can’t accommodate ships of all sizes, poor docking facilities, and so on. However, there is still a lot that can be done to improve the process. By thinking a little differently, you can drastically improve efficiency.
Fully automated unloading
At Veidekke Ottersbo crushed stone plant, north of Trondheim, a new and automated unloading line was recently installed. The technical solution involves conveyor belts that transport the finished goods directly from production to the ship at the quayside.
In simple terms, the desired fraction is discharged into a culvert and transported by conveyors to ship loads. The combination of hydraulic hatches and feed conveyor adapts the right amount down onto the conveyor. Here it is also possible to mix the masses during loading if necessary. All this is controlled from an iPad in a control room. Pretty cool!
Following the conversion of the plant, they have achieved a significant reduction in the use of diesel as most of the machinery is now electric. In fact, they estimate a reduction in emissions of as much as 1500 tons of Co2 per year(!). Another consequence of this is that significant savings are made on expenses that were previously spent on construction equipment maintenance. The capacity for unloading ships at the plant has increased significantly, as boats are staying shorter.
Lack of space and high demand
Rekefjord Stone is a crushed stone plant outside Eigersund that extracts minerals for the production of asphalt and cement, among other things. This is distributed throughout Europe via 700 cargo ships per year. There are two large cargo ships per day. That’s a lot.
Especially when the plant is located at the end of the Rekefjord, which means there’s not much room when it comes to loading crushed stone onto a boat.
On the west side of the plant, they were previously using an inflexible unloader that presented a number of challenges. There was limited space on the quay and boats of all sizes were arriving. With a less efficient unloader, this led to a lot of queuing and waiting. Another problem was that the material was not spread evenly in all holds, which often meant that the boats had to be moved while docked. This quickly becomes a time-consuming process with large ships.
Increased capacity with a tailored solution
The best solution was the most flexible solution. An unloader that is adjustable in all directions to ensure the most efficient loading for ships of all sizes. The loader can be adjusted 14 meters in and out longitudinally, and side-to-side with a 120-degree turning radius. This ensures smooth and efficient loading for ships of all sizes, and has significantly increased capacity at the plant.
Swapped wheel loaders for transporters
Another challenge was the long distance from the rock to the feeding station on the eastern side of the plant. This was solved with a 120 meter long conveyor. Previously, dumpers had to drive to and from the quarry to the ship’s unloader.
This led to a lot of traffic and was inefficient, not to mention expensive.
To put it another way, for every truck you avoid using, you save 1,000 kroner per hour. Money saved is money earned. Now you just load crushed stone into a feeder close to the quarry, and the transporter takes care of the rest. Simple and effective.
We have now loaded 3 million tons without a single error. It has gone flawlessly.
Reidar Solli, Maintenance Manager in Rekefjord Stone
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Grit for the people
Along the Norwegian coast, there are a number of quays that are not suitable for unloading from large ships. In some cases, there isn’t even a quay. But should this mean that you should not be able to receive deliveries of crushed stone? We don’t think so.
Seaworks needed a solution that could replace the one they already had. With that method, they were dependent on the cargo ships being able to dock. We’ve already talked about how this can be a problem, but luckily most problems have a solution.
Let’s take a look at how they did things before. The ships had to remain docked while an excavator located on the ship unloaded crushed stone from the cargo hold onto dumpers that transported it onwards.
Unfortunately, a ship doesn’t always arrive at its destination between 08:00 and 16:00. There are often many stops on the route, and they often sail through the night. This means that the drivers of the dumper trucks had to work through the night, which means hefty overtime bonuses.
The solution was to install a flexible unloader on the ship itself.
All in all, there are more answers than questions, it’s just a matter of designing tailor-made solutions to suit the application and needs. Because when a boat is such an efficient means of transportation, loading and unloading should be just as efficient.
On to something completely different. Want to know how the wrong screen cloth can put an end to profitable production?
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