How are the hard-to-flow bulk solids loaded, transported, and unloaded in general?

Of the many ways to bulk handling materials, some are obviously more efficient than others for specific products, but in general, the logistics operators or the companies that produce and/or use the hard-to-flow bulk solids have already their own way of doing things, to a point that, like most processes, there is always resistance in changing to a new one, even though the new process could offer lower costs to the user.

Initially, we must separate things regarding their volume and distance to be transported or possible modal to be used.

When talking about maritime modals there is a way of bulk handling the material, either easy or hard-to-flow, that will not get into our discussion that is the bulk solids carriers, ships made specifically to carry large quantities of bulk solids, of one or several origins and types. They transport the bulk solids that were brought by some bulk conveying method (pneumatic conveying, belt conveying, bucket conveying, and so on) in their holds, and are unloaded also by similar processes, which are eventually much more efficient than any other modal, but one can only use it for very large quantities.

On the other hand, when one needs to transport smaller quantities or have to split the product to different destinations, the use of other methods is important.

For a long time, companies that produce and transport the hard-to-flow solids have carried them in tank carrier trucks. As those trucks are normally not specifically designed for some specific solids, they will have different performances for the different products. The hard-to-flow bulk solids are even more troublesome once they could clog the pneumatic conveying piping or even the hoppers that were not designed for the specific end, so, part of the hard-to-flow solids started to be transported in big bags placed inside containers instead of bulk tank trucks.

Even being able to split loads more efficiently with big bags, there was still some points that needed to be analyzed once this simple operation affects the total costs of the Supply Chain.

Supply Chain, what exactly is that?

At the beginning of the 1980s, the concept of “Supply Chain” was first used by Keith Oliver from Booz Allen Hamilton in an interview with the Financial Times, this was (and still is) a very strong concept, that leads companies to start to work with idea that the linkage between different events influenced the total end cost of this Supply Chain influencing the total profits or losses of a certain company.

Supply Chains are “Two or more parties linked by a flow of resources – typically material, information, and money – that ultimately fulfill a customer request” as the definition of Dr. Chris Caplice from MIT.

A Supply Chain Operations Reference (SCOR) Model – developed by the Supply Chain Council in the 1980s, breaks supply chains into Source, Make, Deliver, Plan, and Return functions resulting in the basic functions inside the companies: Procurement, Inventory Control, Warehousing, Materials Handling, Order Processing, Transportation, Customer Service, Planning, etc.

From the definitions above we can see that the material handling performs a very important role in the process, so that better or worse efficiency in this portion of the process would affect the whole chain, once the actions from one function impact (and are impacted) by the other functions.

The main idea is that even though one needs to manage the entire system rather than the individual siloed functions, as the sum (or multiplication) of the individual impacts are what generate the whole performance (good or bad) and that a chain is always as weak as its weakest link, there needs to be very close attention to each individual process.

The individual process that we are dealing with, loading – transporting – unloading of bulk solids materials plays an important role inside the whole chain once it somehow regulates the flow of materials (raw), so, if it takes too long it will affect the whole chain negatively increasing the need of inventory while impacting the level of service between the two links (raw material producer and utilizer) of the chain. A bad decision on this portion of the chain may negatively impact the whole chain to the point of a disruption, so that good management of this portion is essential, even though it is somehow hidden from the rest.

What impacts our chain then?

Let us think about the following possible situations:

    1. A mid-sized plastics injection business makes approximately 50 tons of injected material every working day. If this company buys its pelletized resins in bags of 50 kg, it means 1,000 bags a day what will take approximately 72 sqm to be stored a day.
      There are many reasons for holding inventory. These include minimizing the cost of controlling a system, buffering against uncertainties in demand, supply, delivery and manufacturing, as well as covering the time required for any process. If the delivery time of the resins, plus purchase time, plus transportation makes the total lead time of about 14 days with a standard deviation of 1, the minimum inventory that needs to be held to guaranty a 96% level of service will be approximately 800 tons. This leads to a 1,152 sqm of warehouse necessary to hold this raw materials inventory plus 25 people and 2 fork trucks to handle it; This means a high holding rate considering the costs of building rent, plus all handling costs.
      There is, however, a problem with having too much inventory: the excess inventory can lead to losses, spoilage (excess moisture and many other forms for instance), obsolescence (deterioration), and damage.
      Spending too much on inventory also limits the resources available for other activities and investments. Inventory reduction in the determination of the right amount of inventory of the raw materials and products.
      Inventory management is at the core of all supply chain and logistics management because it represents high costs.
      If instead, this material is transported in 20ft containers, using container bulk liner bags, the total needed area will be reduced to 450 sqm, and the total number of people reduced to approximately 4 with no forklift needed. There will be some investment in tilting rigs or the need for trucks with tilting capabilities and silos, but the operation is much faster and those investments are quickly returned by the improvements in the supply chain.
      This shows the big difference that this little change in the process can do to the whole supply chain, and we are not talking about a hard-to-flow product that would require even more handling manpower, which could be solved using the Tiltless Liner System.
  1. A concrete distributor that sends 400 metric tons a day of concrete to their customers:
    To make this 400 metric tons a day they will need approximately 150 metric tons of cement.
    It is completely unpractical to use 50 kg bags in this case, but there are still 2 possibilities:
    – Use of 2 metric tons big bags (75 a day)
    – Use of bulk cement carrier trailers – (3.5 a day)
    The first possibility has a need for the storage area to hold at least a day of supply before it is transferred into the silo, plus a need for 1 fork-truck and 8 people to handle the operation, while the second one has the cost of the empty trailer travel plus the investment on specific trailers, creating a maximum radius of action smaller than 100 miles to be competitive, while the more flexible answer is the use of bulk lined 20ft Standard ISO containers that will use as little as 2 people with no fork-truck to operate the discharge, plus no need for “quick storage” once every container is directly dumped into the pneumatic conveyor system that leads to the silo and the containers can be used to transport other merchandise in the way back, optimizing the use of it, reducing the cost of return of them, as well as not investing in specific trailers that can only be used for this purpose. The use of fluidized liners will reduce even more the time to unload the materials, reducing also the tilting angle necessary for discharge, which makes most tilting truck chassis suitable for this kind of operation, reducing, even more, the costs to operate the transportation of this kind of product.
  2. Many hard to flow bulk solids transport processes:
    On many processes as with animal food, dehydrated eggs, or powder milk (hard to flow common bulk solids materials) where most companies use 50 kg bags or silo trailers, can reach important handling cost reductions by means of using container liner bags, and bigger cost reductions for lowering discharge time and lowering investment needs in special equipment, while reducing the time spent in the discharge operation, handling labor and warehouse or a storage area.

A common answer?


The fluidizing systems can help to process the unloading operation of the hard-to-flow bulk solids materials to a point that the BULK FLOW fluidizing liners bring success to your hard-to-flow discharge operation, reducing times, labor, storage room, and increasing your company’s profits by reducing the total landed cost of the products.

We will be pleased to help you improve your logistics process methods and create a much more efficient Supply Chain, generating profits for your company.

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Posted by Team BULK FLOW

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