Storage & Transportation

Bulk cargo is anything that is transported in large quantities without packaging or packing, where the means of transport itself acts as a container. Volume or mass measurements are used to quantify cargo in these cases.

The type of bulk material determines the means of transport. Construction debris, gravel, or sand can be transported in dump trucks or high-sided trucks. Weather-sensitive goods, such as salt or sugar, require a silo vehicle for transport. Vehicles with push floors are also used or the bulk goods are transported as bagged goods or in big bags. In sea freight, bulk goods are transported in bulk holds or bunkers on the ship.

The most common means for the transportation used to transport bulk solids are the following:

• Trucks
• Ships
• Silo vehicles

Bulk solids are stored in tanks (either above or underground), containers, silos, hoppers, and more, depending on quantity. The storage facilities must be designed such that they neither impair product quality nor cause disturbances to the removal of the bulk solids.

Bulk material storage is either used for buffering between different handling/processing steps or as an equalizer in batch-wise working processes.

Silo’s

A silo, also known as a bin or bunker, generally consists of a vertical cylinder and a sloping. The first step in the process of silo selection is to decide on the type that is required. There are three types of bins:

• Expanded flow
• Funnel flow
• Mass flow

Characteristics to select the best storage equipment

• Maintain reliable feeder flow
• Focus on discharge rather than storage
• Avoid using assumed bulk material flow properties
• Consider a standard design
• Consider combustible dust hazards

For transportation, ships are highly favored for their ability to transport bulk solid goods be it cement, grain, coal, or crude oil at a relatively cheaper cost than the alternatives. It is important to note that the loading and unloading of ships depending on the cargo being transported and the equipment available on the ship and dock.

When moving any freight, there are 4 components of cost, namely: downtime, load time, travel time, and unload time. Downtime and travel time are under the control of the ocean freight company, whereas they are at the mercy of the port facilities for load and unload times.

All ship loaders and ship unloaders serve the same basic purpose: to load or unload bulk materials as efficiently as possible.

To make a well-founded decision on which loader or unloader is the best solution for your terminal, basic issues have to be considered and evaluated, such as total costs, energy consumption, availability, safety, etc.

The following services are required:

• low operating costs,
• environmental compatibility in terms of dust and noise,
• minimum weight and dimensions,
• ease to operate and good mobility,
• flexibility in the loading or unloading of different types of bulk materials,
• reduced times for cleaning the system between operations on different types of materials,
• possibility of carrying out operations even in bad weather (with the hold partially covered),
• complete loading of unloading of the hold with the minimum amount of human involvement inside the hold.

Bulk trucks are a flexible, efficient way to distribute huge volumes of bulk solids.

Although many facilities that require large-scale materials deliveries rely on them being transported by rail, the majority turn to secure their supply via road-based truck deliveries.

Truck loading and discharging these bulk solids is a major logistic issue and has to be managed.

Truck loading and truck unloading systems give a strong capability to move around these materials efficiently, safely, and economically due to their excellent design and robust construction.

Discharge aid devices are devices that stimulate or improve bulk solids flow out of bulk storage containers. Items may be installed downstream of discharge aids to provide a means to shut off or regulate the flow of bulk solids. Some examples of discharge controllers are the slide gate valves and feeders. A discharge system can either be integrated with the silo or installed as an add-on. The primary purpose of a discharger aid is to promote flow, not necessarily to regulate it, and without regard to the order of zone discharge.

A distinction is made between three different kinds of discharge aids, each of which requires a supply of energy:

• Pneumatic discharge aids: function using fluidization, gasification, air blasts, air cushions
• Mechanical discharge aids: function using vibration, discharge agitation, sliding frame
• Vibratory discharge aids: These are used to address flow problems like arching, ratholing, or incomplete material withdrawal
• Manual discharge aids: tapping, poking, and more

Being an integral part of the bulk solid handling process, loading bellows provide dust-free and safe out loading of powdered and granular materials to trucks, ships, and stockpiles. They are generally mounted underneath silos, hoppers, or installed at the end of conveyors like screw feeders, elevators,or pneumatic conveying systems.

The main idea behind the loading bellow system is discharging the powdered or granular bulk solid through a vertical column by its own weight. It collects the dust within the enclosed column upwards. The varying height between the upper discharge point and lower loading point is compensated by making the column flexible.

Depending on the process requirements of the product, loading bellows are available with an extensive range of bellow configurations. The range looks as follows, each with its own characteristics and use cases:

• Single Outer Bellow
• Double Bellows
• Single Outer Bellow With Internal Wear Cones
• Double Bellows With Internal Wear Cones
• Single Loading Chute
• Single Outer Bellow With Internal Loading Chute
• Loading Chute With Double Dust Collection Bellows

Silos are large structures that are used to separate and store different types of bulk materials, such as grain, coal, cement, carbon, and more different bulk goods. It generally consists of a vertical cylinder and a sloping. Three types of silos are in widespread use today: tower silos, bunker silos, and bag silos.

Tower silos are cylindrical structures, typically 30 to 275 ft (10 to 90 m) in height. They can be made of many materials, such as wood staves, concrete staves, cast concrete, and steel panels. An advantage of tower silos is that the silage tends to pack well due to its own weight, except in the top few feet.

Bunker silos are trenches, commonly with concrete walls, that are filled and packed with tractors and loaders. The filled trench is covered with a plastic tarp to make it airtight. These silos are usually unloaded with a tractor and loader.

Bag silos are heavy plastic tubes, usually around 8 to 12 ft (2.4 to 3.6 m) in diameter, and of variable length as required for the amount of material to be stored. They are packed using a machine made for the purpose and sealed on both ends.

A hopper is a large, pyramidal, or cone-shaped container that holds matter or flow-able material such as dust, gravel, nuts, seeds, and more. Hoppers are used for the temporary storage of said materials. They are designed so that stored material can be dumped or fed to a process easily.

Different types of hoppers

• Stretch hoppers: Like self-dumping hoppers, stretch hoppers are designed to be moved and dumped easily with a forklift. The main difference being their design
• Self-dumping hoppers: Self-dumping hoppers are designed to dump materials out the side without needing an external motor or pulley
• Drop bottom hoppers: Drop bottom hoppers are designed to minimize the hopper’s footprint while maximizing the storage space

Key hopper features

• Center discharge
• Strength and durability
• Multiple sizes
• Smooth interior

This section offers an insight into the latest innovations in bulk solids storage systems and dry bulk materials loading and unloading technologies.