Discharge (unloading) of copper concentrate from marine vessels: dominant method is crane grabs. Typical nominal discharge rates range from 300 to 400 tonnes per hour, max. rate encountered in practice was close to 600 tph.

Note that the rate declines when collecting the final 10 to 20% of concentrate from a hold due to dozing, sweeping, etc. ■

Kolkata

Oct 09 '03

Dear Mr. Velan,

We are presently supplying an equipment for this.

Please let us know your requirement in detail.

Regards

Shibaji Dasgupta ■

Dear Mr. Velan,

We have been offloading copper concentrate vessels and used two methods.

On very old vessels, still having dereks as ships gear, we offloaded by means of skip buckets.

A front-end wheel loader was placed in the hold to fill the skip bucket with the cargo.

Subsequently the skip bucket was lifted by the ship's gear and discharged directly into a dumper truck with minimal spillage.

Operation can take place at 2 holds.

A slower operation, but cheap and allright for smaller cargoes up to 10,000 MT

For a ship with ship's cranes we offloaded with two 10CM grabs which can firstly open partly. Direct delivery into dumper trucks, with a little more spillage due to the grab size being bigger then the truck.

However, cleaning up is easy with a front-end wheel loader.

Faster offloading, but cannot give you figures as we were waiting for transport.

Tarpaulins are placed between ship and shore to collect any spilage from falling into the sea.

For smaller annual quantities I feel investment in special discharge equipment is not justified.

The product is not always uniform, but grab operations went OK. ■