In 2018 companies performing coal handling in Riga port (Latvia) began relocating to new jetties. According to the new city development plan, all bulk terminals must be moved from the city centre to areas distant from the residential districts. This will improve environmental situation and reduce the load of freight transport and railway.

Stevedoring companies faced the issue of upgrading cargo technology to move to a new location. The unstable situation on the coal market also made it difficult to make decisions in favour of large investments in new equipment.

Against this back­ground, Latvian production company TTS offered the Riga Central Terminal to implement a coal transshipment solution using fully mobile equipment. This solution has four main advantages compared with traditional port equipment:

* short term commissioning of equipment — less than six months;

* construction of expensive foundations and engineering networks is not required;

* lower cost of equipment; and

* possibility to use the territory of the sea terminal more flexibly.

An important condition for the customer was to ensure the performance of the equipment — 1,000 tonnes per hour. In addition, coal in piles must be at least 140,000 tonnes. Plus cleaning of tramp metal and crushing to a fraction of 0–50mm is to be performed. For loading into vessels, stevedores wanted to use already existing portal cranes. Following these requirements, TTS engineers developed technology for coal handling using mobile equipment.

The cargo enters the terminal in railroad cars. Hydraulic grapple cranes unload cars and deliver coal into two receiving hoppers. Each hopper is equipped with a grate for screening large pieces of frozen coal.

Two chain feeders deliver material to the conveyor line, where a self-cleaning electromagnet removes tramp metal. After cleaning, material enters two-roll crusher for grinding. Once crushed, coal fits into a transitory pile by radial stacker.

Crushing and stacking

From here, wheel loaders deliver coal to radial stackers, which form stacks in the area of portal cranes. These radial stackers are able to form 17 metre-high stacks. Such height makes it possible to store a large volume of coal in a small area. In addition, the boom of the radial stacker has a variable height, which significantly reduces the formation of dust, while the stack of cargo has a small height.

None of the equipment, including receiving hoppers and crusher, requires foundations and can be moved to another berth zone within a few hours. This solution makes it possible to quickly reorient the terminal to load not only bulk cargoes, but also breakbulk.

The design of the equipment makes it possible to process not only coal, but also other bulk cargoes — including ores, green fuel, aggregates, wood chips.