Originally Posted by dcasanova

Urea bulk ship unloading and transport to warehouse

Hi, I'm currently involved in a short project for optimization of granular urea transport from ship to warehouse.

Our current unloading procedure is done by the ship's own crane/clamshell bucket that deposits all material on the quay which in turn is transferred into a dump truck by a front loader (shovel). This truck travels to a nearby warehouse, located about 2 km away, unloads all its cargo onto the floor and returns to the ship to be loaded again (actually, many trucks are involved). At the warehouse, another shovel is then used to gather and pile the material.

A conveyor belt system actually exists for this purpose but it's been inoperative for more than 10 years and reparation costs have been deemed excessive (haven't seen a return of investment study, though). Since there's an operational expense for equipment rental, the procedure is somewhat risky and some product is lost during transfer, there's still incentive to evaluate alternative loading/unloading solutions.

We currently receive 8000 ton shipments each month which are unloaded according to the above procedure in about 5 days (1500 to 2500 ton/day). Warehouse space is just enough to hold all this material because shovels can only achieve 3-meter high piles whereas original design accounted for about three/four times this figure, so storage optimization would be another benefit from a different unloading machine.

Mobile pneumatic machines have been proposed for unloading the ship and trucks, but there's some concern about possible particle fracture and atmospheric moisture absorption. Does granular urea share the same pneumatic conveying limitation of prilled urea? Will air transport further increase moisture exposure in comparison to mechanical grabbing? Should we forget pneumatic systems altogether and concentrate on restoring the belt conveyor system?

Thanks in advance.

It all depends on your pocket book and how well or sick it is pretty much.

Another option that would be an excellent choice is the pneumatic tank trailer where it can vacuum

the urea into the trailer or load it from the top by using hopper filled by the shipboard crane (no urea in the ground/no dirt in the urea).

You would want to keep the mobile hopper covered or placed in storage to keep it out of the sea air,

Towing it away to fresh air between loads to prevent salt air rusting the collection hopper.

The pnuematic tank trailer can off load the urea into to discharge piping and fill the storage as high as you wanto fill it within reason and

the storage capacity of the bins.

A small fleet of pneumatic tank trailers could be used to carry the urea from port to storage and the trailers could be unloaded by a stationary

pneumatic system at the dump site eliminating the need to purchase trailers with pneumatic systems installed on the trailers.

It would be advisable to have two permanent systems installed at the storage site to allow unloading of two pneumatic trailers at a time and

also have to the abilty to have a spare just in case one of the pneumatic systems breaks down. ■

Dear Sir

We noted your requirement for a Urea Unloader. Our Portable Siwertell Screw type unloader should work nicely. Rated 300tph.

Please feel free to contact us.

Sincerely,

Al Goodmundson

Email norsequip@sasktel.net

Phone Canada (306)-664-7260 ■

Dear dcasanova,

Your worries about urea degradation and moisture absorption during pneumatic conveying are real.

The cost, involved in building and operating a pneumatic unloading and pressure conveying system for 2 km is probably as much or more than refurbishing the belt conveyor.

Using a loading hopper to fill the truck could save you some labor and a shovel on the dock.

A hopper with an elevating mobile belt could pile the urea higher.

The turnaround time of a pneumatic bulk truck is longer than for the truck and therefore, using pneumatic tankers requires more units.

I believe the best way to go (but you have to do the research) is to keep using the grab crane (de most efficient type of unloading bulk goods) an add a loading hopper (also functioning as a surge hopper).

Then use a mobile elevating belt conveyor in the warehouse for piling up the urea.

If these improvements are not sufficient, investigate the repair of the 2 km belt conveyor.

Take care

Teus ■

Dear dcasanova,

Your existing bulk truck dumps the urea faster than a pneumatic bulk truck can unload.

However, when a pneumatic bulk truck can transport 25 tons and your bulk truck only 5 tons, the overall transport capacity of a pneumatic bulk truck could be higher.

The application of pneumatic bulk trucks require:

-pneumatic bulk truck loading hopper filled by the grab crane

-pneumatic bulk trucks

-discharge pipe(s) into the warehouse

-Filter/fan assembly on the warehouse

Furthermore, you have to establish the pneumatic convey ability and the conveying capacity of the urea.

The particle size and the particle density are ruling parameters here as well as the local conditions (Temperature, humidity and altitude above sea level)

Ask the supplier, whether they use pneumatic tankers for their deliveries.

Pneumatic tankers are sold around the world and hoppers are manufactured normally locally as tailor made units by companies in the bulk handling business.

Now you have 4 options so far:

1)Existing installation (grab crane, front loader, 5 tons truck, front loader)

2)Loading/surge hopper (grab crane, hopper, 5 tons truck, dump hopper, mobile belt conveyor)

3)Pneumatic solution (grab crane, hopper, pneumatic trailer, pipeline(s), filter/fan)

4)Repair of existing 2 km belt conveyor.

Actually all systems have to be evaluated for a decision.

Have a nice day

Teus ■