Millions on the line: compare the right figures | Bruks Siwertell
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Millions on the line: compare the right figures

8 Sep 2021

Dry bulk handling equipment lasts for decades, so a long-term view and comparing the right figures at the point of investment will pay dividends, potentially saving an operator millions of dollars, explains Jonas Fack, President, Bruks Siwertell AB.
High on everyone’s agenda is economic, social and environmental sustainability, and how we can all navigate and grow our businesses during this time of massive transitions. One of the ways that we are meeting our commitment to support the United Nations (UN) sustainability goals and positively contribute to environmental protection is through our dry bulk handling technology.

Our Siwertell screw-type unloaders offer the most environmentally friendly way to discharge dry bulk materials off a ship. They ensure that operations are dust free and eliminate wasteful practices such as spillage. Furthermore, they deliver very high through-ship capacities, reducing the time a vessel spends in port, which in combination, means that operators can not only save considerable sums of money, but can positively impact the environment. So, even if environmental concerns are not the main driver for change, they automatically come hand-in-hand with our equipment.

Simple, but complex

Comparing the right figures seems simple in practice, but we do understand that to build a calculation model, which includes all the aspects that need to be considered, is not so easy. At the same time, it needs to be structured in such a way that calculations provide meaningful comparisons and evaluations for different types of equipment.

So, what should be considered when making an investment in dry bulk handling equipment? Firstly, we need to look at actual through-ship capacity, where all the movements of the ship unloader and the handling of other equipment, such as payloaders, are included. A higher through-ship capacity reduces unloading times, translating into reduced vessel costs and the costs of the operation as a whole. Also, if the jetty is less occupied, the port has the opportunity to receive more vessels over the course of a year, boosting jetty utilization rates, and increasing through-put and terminal profitability.

Secondly, we would ask operators to consider total investment costs, including the actual jetty construction. Depending on the type of equipment, the weight of screw-type unloaders, bucket chain unloaders or grab cranes varies considerably. The higher the weight of the equipment, the higher the jetty construction or reinforcement costs. Jetty reinforcements, to accommodate heavy bulk handling equipment, can easily correspond to fifty percent of the cost of the actual equipment.

Also, rail span is an important factor. If the unloader can be designed to have a narrower rail span, the width of the jetty can be reduced, which again saves money.

Removing the waste

Thirdly, dust- and spillage-free unloading is essential, and not just for the environment. It is a well-known fact that a grab unloader has a much higher degree of spillage and dust control compared with totally enclosed systems such as pneumatics or screw-type unloaders. Spillage literally wastes cargo, and also incurs clean-up costs, and both damage the environment, but this is difficult to quantify. 

However, when unloading dusty materials, the terminal’s surrounding areas are impacted by the operation. This is often accentuated if you have residential zones close by or a marina, or other commercial operations sensitive to dust. Globally, government authorities demand much higher dust emissions standards for operational permits, which is why this should be considered early in the planning process of a new terminal.  

Lastly, but no less important, are maintenance figures. The long-term costs of servicing equipment and the lifetime of wear components should be at the forefront of an operator’s mind when considering any investment, especially considering the longevity of dry bulk handling equipment.

For ship loading equipment, similar comparison figures need to be held in mind. However, in general, loaders offer much higher through-ship capacities, as there are no clean-up costs, and maintenance costs are lower, as no vertical lifts of material are required. But long-term operating and servicing costs are pertinent and most ports today have very high requirements for dust and spillage.

Consider all factors

Calculations do vary for different materials, so these should always be part of the mix as well. Some materials are simply more difficult to handle because of their intrinsic characteristics. For powdery materials, the issues of dust and spillage preclude the use of particular types of dry bulk handling equipment entirely. A good example are operations that import cement. This material is almost 100 percent handled by either pneumatic unloaders or screw-type unloaders; grab cranes are not used because of issues around dust and spillage.

Environmental considerations aside, just looking at spillage in terms of costs, depending on the equipment you are comparing, savings can extend to millions of dollars a year. For example, some operators state that their grab unloader can spill between two and four percent of a shipment, depending on material. If the cost of the material is, for example, USD 100 per metric ton and the annual intake is two million metric tons, actual losses due to spillage could be as much as USD four to eight million per year.

Calculations for which equipment best suits a terminal need to be related to its annual volumes, types of materials handled, as well as ship size. This delivers the best results.
Although it is difficult to give an accurate comparison of through-life costs for each piece of dry bulk handling equipment, if an operator has to make an early reinvestment in equipment because of reliability issues, or running, or maintenance costs, this will have a negative impact on terminal profitability due to the cost of the loan, as well as the cost of depreciation. 

Different needs, different calculations

Some calculations become more complex depending on the nature of the project, for example, if it is a new terminal or port, or an expansion of existing facilities. For expansion projects, a number of set parameters already have to be followed and there are infrastructure limitations that are often in place. 

These are not present for newbuild projects, and so there are potentially greater savings to be made from the outset, certainly in terms of weight and rail span. The main cost savings that directly relate to equipment are the costs for the jetty. 

The weight of a Siwertell unloader is much lower compared with a bucket chain or grab unloader. When comparing equivalent capacities and ship sizes, the difference is typically between 30 and 40 percent lower for a Siwertell unloader. They potentially also require in the region of 40 percent less rail span, reducing the space occupied on the jetty and/or the required width of the jetty.

Do the maths, it is worth it

However, in all of this, given the service life of port equipment, in almost every case, the cost for the entire operation, including maintenance, is the most important factor. To put some figures on this, take two types of equipment: both offer a rated capacity of 1,500t/h, but one has a through-ship capacity of 60 percent, and the other 70 percent. 

If a terminal has an annual intake of two million metric tons, and the equipment operates for 22 hours a day, at 60 percent, it will provide a through-ship capacity equivalent to 900t/h, delivering 2,222 operational hours per year, or 101 days per year. At 70 percent, this equipment has a through-ship capacity equivalent to 1,050t/h, so the number of operational hours per year will be 1,905, or 87 days per year.

This is a difference of 14 days a year, so if the cost of the vessel stands at around USD 30,000 per day, the savings per year will be USD 420,000, and over the lifetime of the equipment, say 25 years, this builds to an impressive USD 10.5 million. 

Some might see it beneficial, then, to increase the discharge rate to 2,000t/h for the equipment that can offer 60 percent efficiency; but it will still only deliver a through-ship capacity of 1,200t/h, and be considerably more expensive. However, if you have equipment than can deliver 70 percent efficiency, you could, in fact, reduce the discharge rate of the equipment to 1,700t/h and still have the same through-ship capacity. This makes far better economic sense, as an operator can buy unloading equipment with lower capacity, but still have the same efficiency. This generates significant savings, not only from the cost of the equipment itself, but also for the conveyor system that serves it.

I should point out that Siwertell screw-type unloaders offer a minimum through-ship capacity of 70 percent.

Sustainable choices

We are suggesting that before an operator chooses any new dry bulk handling equipment that it considers all the options. They might be very surprising. We have developed a value calculation tool that helps compare the complexities of calculations and we are happy for our systems to be compared with all other mechanical and pneumatic ship unloaders and loaders on the market.

The choice an operator makes today can impact a terminal decades down the line. We are encouraging the industry as a whole to not only consider the best economic decision, but also the best environmental one too; and our systems offer both.


Jonas Fack
President, Bruks Siwertell AB

Jonas Fack

+46 766 771501

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