Fertiliser dust sifters – a difficult mission complete

Fertiliser dust sifters

Fertiliser dust sifters – a difficult mission complete

Problem:

  • a fertiliser manufacturer faced the following problem – during the storage and transport of granulate, dust is formed which reduces the quality of the product;
  • adverse health effects and corrosion of equipment caused by dust can have a negative effect on the company’s bottom line;
  • high performance of up to 150 t/h and small equipment dimensions – these are the key challenges for the new machine.

Remedy:

  • tests conducted using a VFE sifter® have proven its effectiveness.
  • this way, we were able to decide on the dimensions of the equipment and confirm its performance;
  • we have delivered a sifter which meets all the stringent requirements.

High dust extraction performance

The sifters remove dust fractions below 0.5 mm at the capacity of 100 – 150 t/h

Compact size

The units offer high performance despite small dimensions (1.25 x 3 m). This made it possible to install them in the small space available in the building.

Testing at the customer's site

In order to prove the effectiveness of the sifters, we have conducted tests at the customer’s site. This made it easier for the customer to make a quick decision.
sifter for chemical fertilizers

VFE® sifter for chemical fertilizers (4 units, top section of the picture) – example

Corrosion and threat to human life

Corrosion, caking and jamming agricultural equipment as well as negative effects on human health – these are the most important, but not the only, drawbacks resulting from the presence of dust in a fertilizer. For example, dust from certain fertilizers poses an explosion risk.

In this particular case, dust is generated by the friction of the granules against each other during storage and on-site handling. Currently, there is no way to completely eliminate it from the final product. However, manufacturers do their best to keep the dust presence as low as possible.

Tough requirements

One way to eliminate dust is to sift the finest fraction. This was the solution chosen by our customer. However, it came with very stringent requirements. Based on our detailed survey and the letter of inquiry, we have contained these requirements in the following four points. Namely, the sifters must guarantee:

  1. high sifting efficiency for fractions below 0.5 mm with capacity of up to 100-150 t/h;
  2. many months of failure-free operation – the equipment is one of the key elements of the packaging installation which must ensure reliable operation at the peak of the season;
  3. automatic screen cleaning during operation to prevent clogging and reduce maintenance to a minimum;
  4. compact design with high performance, as the equipment must fit into the existing transport system and little space is available.

Upon analysing the above points, one can easily conclude that the project is very demanding. The ability to sift fine fraction combined with high performance and small dimensions of the equipment is a deadly combination of requirements which only a handful of suppliers can meet.

First, the tests

We approached the project carefully, because a mistake made at this stage could cause a lot of problems in the future both for us as well as the manufacturer. Deliveries of devices which, ultimately, fail to deliver the expected performance are not that rare explains Krzysztof Wnęk of WOLFF GROUP, who is responsible for the implementation of this project.

We offered the customer to conduct tests with their product. This not only allowed us to select the optimal equipment dimensions, but also to confirm that VFE® sifters will achieve the required performance and dust sifting efficiency. The tests were conducted at the investor’s plant so that he could see the effectiveness of the proposed solution with his own eyes.

This step was extremely important because VFE®sifters work in a unique, patented way. When we attempt to explain its operation without the prop in the form of an actual, working unit, the reaction is mostly a combination of surprise and disbelief. At best customers respond with curiosity – says Mr. Wnęk. If you would like to conduct a similar test without undertaking any commitments, it is absolutely possible. Check out the information below or continue to read the implementation description.

Perform a no-commitment test with your product

The sifting efficiency of this equipment, even when used with very fine powders like limestone dust, is so high that we have successfully substituted it for an air separator in one of the plants. We are looking for companies willing to challenge the status quo at their production facility and would like to test the efficiency of sifting of their product with our machine.

Krzysztof Wnęk
Grupa Wolff

Everyone is surprised to see that it actually works

The way this equipment works seems to contradict the fundamental principle that has guided sifting equipment manufacturers so far. This unique character makes VFE® sifters achieve very high sifting efficiency at low purchase and maintenance costs.

What makes it unique?

First of all, in the case of VFE® sifters, the screen is not stretched. It is only attached at the top, so that it rests freely on the support deck. Installation is done by screwing in three standard screws. I don’t mean to say that you can do any old way, but it certainly doesn’t require any special tools or skills.

It takes only 6 minutes to replace the screen

The screen is additionally sealed on the sides by so-called skirts, which are in turn fixed to the construction of the sifter by means of magnetic strips. All this means that one person can replace the sifting screen in about 6 minutes. Please watch the video below to see how easy and quick it is to replace the scree

Unique vibrations

Let us return to the question of the unique nature of our sifter. After all, a loose screen is not going to cut it. If we applied a similar solution in another sifter… it would stop sifting.

The secret of our sifters lies in patented vibration inductors made of special elastomer and metal. It is these inductors which turn small vibrations generated by two small vibrators (motors with unbalanced masses) into asynchronous vibrations of the screen characterised by chaotic frequency and high acceleration. It sounds complicated but, basically, the idea is that the screen waves across its entire surface – it is elevated in one spot while it drops in another.

 

Tak wibruje siatka w przesiewaczu VFE

Screen vibrations in a VFE®sifter

 

The combination of a loose screen with the inductors has six fundamental advantages which were appreciated by the investor:

  1. the screen vibrates in a very dynamic manner and therefore guarantees efficient sifting;
  2. the freely waving screen does not get clogged with the product – the effect is similar to shaking out a blanket;
  3. vibration inductors significantly reduce the energy consumption (the equipment described herein consume the same amount of electricity as two electric kettles while offering the capacity of 100-150 t/h);
  4. screen replacement is very simple and quick (one person can do it in 6 min.);
  5. only the screens are made to vibrate with an appropriate energy – the housing of the equipment vibrates only at a minimum degree, which means that virtually no dynamic load is transferred onto the supporting structure;
  6. parts subject to wear and tear have been reduced to a bare minimum – so if you associate sifters with costly repairs, this is not the case at all.

Delivered sifter

In order to meet the investor’s requirements, we delivered and installed two 1.25 x 3 m VFE® SD sifters. The equipment is used to sift fertilizer granulate in the form of ammonium nitrate (a chemical fertilizer based on ammonium nitrate with the addition of dolomite or sulphur stone with granulation from 1 mm to 5 mm). The goal was to remove dust fraction below 0.5 mm from the final product.

The sifters are doing their job to the fullest and at this point, almost a year after their installation, they have been working without a single failure – concludes Krzysztof Wnęk.

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