Key Benefits

  • Safe, efficient discharge
  • Flexible storage options for a range of materials
  • Complete reclaim
  • Low maintenance
  • Low energy costs

Energy-efficient blending, storage and reclaim

You have a lot of choices for your blending silos and storage . Each has different strengths and characteristics, allowing you to choose the best fit for your application. And you can be sure that whatever you choose will be low-dust, high-efficiency and long-life.

Storage solutions to keep your process moving

Whatever material you’re storing and however it fits in to your process, efficient and complete reclaim is always a priority. It impacts productivity and profitability – not to mention safety. Problems retrieving material from storage can be a major bottleneck to your operation.

This is why we have prioritized First In – First Out in all our silo designs. By keeping material moving using controlled flow technology, your materials are held safe in storage and easily reclaimed. With First In – First Out built in as standard, you can choose from our range of silo technologies in accordance with your needs. 

CF silo for raw meal

Achieving homogeneity in your kiln feed is vital. It affects everything, from the stability of your pyro process to the quality of your end product. The impact of a poorly balanced raw meal composition in kiln feed is felt on fuel efficiency, refractory life and, most evidently, your bottom line. So how do we make sure your raw feed remains consistent?


The answer can be found in the CF (Controlled Flow) silo. Originally launched in 1981, this unique concept continues to deliver high homogenizing efficiency and low maintenance costs. Layers of raw meal are fed into the silo in a carefully controlled sequence that promotes mixing as the product moves through the silo.


Key to the successful homogenization and discharge is the clever silo bottom, which is divided into seven hexagonal sections, each of which is split into six segments around a central outlet with a conical steel cone. The outlets feed the material continuously at different rates – giving you efficient and consistent homogenisation. Every segment has an aeration unit, ensuring easy and complete storage reclaim.


As part of the kiln feed system, the raw meal leaves the silo via Airslide® conveyors and enters a mixing tank mounted on load cells, giving you complete control of your kiln feed for a stable and efficient pyro process.


Key benefits of the CF silo


Our state-of-the-art silo systems give you:

  • High kiln feed stability and consistency – Continual adjustments made by the Controlled Flow silo ensure stable kiln operation.
  • Outstanding homogenisation efficiency – The control panel determines the sequence of extraction, opening of valves, and aeration of each segment.
  • Power-saving design – Our Controlled Flow silo delivers efficient air and power consumption by aerating only one segment in each of just three of the seven outlets, out of the 42 total sections.
  • Low maintenance – Adjustments are only infrequently needed to the kiln speed and firing rate.
  • Smart design with filters to prevent blockages – The air supply system to each section has a filter that cleans the air and prevents material from entering in case of leaks in the aeration system inside the silo. If desired, each individual segment can also be supplied with a filter.
CFI cement storage silo, fly ash and other similar materials

Whenever you’re storing fine, powdery products, cohesion can be a problem. The materials stick together and to the silo walls, making it very challenging to reclaim. Manual clean-up is difficult and dangerous work – to be avoided at all costs. What you need is a silo that prevents agglomeration in the first place and assures the “First In – First Out” principle.

We developed the CFI (Controlled Flow Inverted Cone) silo based on the successful design of the CF silo, which is used for raw material storage. The design makes use of individually aerated segments to keep material moving and prevent build-up.

The CFI silo bottom is divided into 6, 8, 10, 12 or 14 sections depending on the silo diameter, which can be anything from 10 to 30 m. Each section is fitted with an aeration box and slopes 10 degrees towards its respective outlet at the base of the inverted cone. To keep energy consumption to a minimum, only two sections are aerated at a time. This combination of factors ensures easy and complete reclaim as well as low energy and maintenance costs.

CFS cement storage silo and other similar materials

Are you concerned about the environmental footprint of your cement storage? Silo reclaim can be surprisingly energy intensive – which is why we have developed the CFS (Controlled Flow Storage) or Flat Bottom Silo with incredibly low power consumption.

The CFS silo bottom is divided into six sections, which can be anything from 10 to 16 m. Each section is fitted with an aeration box and slopes 15 degrees towards outlet at the centre.

The aeration system can be made even more efficient with the addition of filters to prevent material from making its way into and blocking the entire system.

The CFS design builds on our long experience with controlled flow silos to give you the ultimate low-maintenance option for your storage demands.

CFMI silo for storing multiple products

How do you handle the storage requirements of manufacturing multiple products? You could choose to have multiple storage facilities, if you have the space and the logistics to make it work – or you could opt for a more compact solution that can handle all your storage needs.

The CFMI (Controlled Flow Multi-compartment with Inverted cone) silo was developed to be that flexible alternative. Based on our successful controlled flow technology, it guarantees complete “First In – First Out” and reliable reclaim of multiple products thanks to a truly adaptable internal structure. You can choose from silo diameters from 10 – 30 m, with multiple compartments designed according to your need (and civil engineering requirements).

We’ve designed silos with two compartments, silos with four compartments – even silos with seven compartments. As with the CFI silo, each compartment floor is divided into aerated segments to ensure easy discharge. You can choose from the inverted cone type CFI silo bottom or a combination of a flat-bottomed CFS silo and inverted cone CFI design. The raised silo bottom leaves plenty of room underneath for the installation of packers, mixers and/or bulk loading equipment.

With such a flexible offering, the best thing to do is talk to our experts about your needs so that we can help you decide on the optimal solution for your process.

MDS silo for long-term storage

Seasonal demand and supply can mean long-term storage of bulk products for 6 months or more. In that time, it’s common for material to build up, forming lumps and bridges that are almost impossible to displace without risky manual intervention.

The MDS (Multi-Dom®) silo provides large storage capacities of up to 40,000 m3 and is especially suited to long-term storage. The silo bottom is divided into aerated segments that each feed to their own discharge point. Using a minimal amount of fluidizing air, each segment is aerated in turn to ensure stable flow. A special technology avoids material build up that would form lumps and bridges. Material can even be discharged and conveyed back into storage, ensuring that when the time comes for the product to be put to use, it is ready to go.

Pneumatic blending silos for virtually any application

Pneumatic blending technology maximises the benefits of fluidisation and gravity to achieve complete blending with low power consumption. Our range of pneumatic blending silos caters for high capacity, low pressure and low dust applications in bulk materials industries.


RANDOM-FLOW™ blender
This space-saving system gives maximum storage capacity and includes space on the ground floor. The Random Flow™ Silo design uses six pie-shaped sectors, which are each subdivided into six aeration zones, and a timed discharge pattern to achieve continuous blending with the lowest possible energy consumption. Low pressure air is combined with gravity withdrawal, giving you maximum cleanout with power consumption as low as 0.07 kWh/metric ton for raw meal. And because there are no moving parts, it’s a very low-maintenance system.
Airmerge™ blending

The gentle blending action of the Airmerge™ system gives a near-perfect blend that’s even suitable for food applications. Air blending is achieved by use of a porous membrane over the entire bin bottom, four air plenums and a simple flow control system. Together they change the density of material in the fluidized bed of material to generate a gentle folding action and a near perfect blend.

Higher air velocities in the blending quadrant lower the bulk density causing the denser material in the three fluidized quadrants to flow into it and be displaced upward in a continuously circulating bed.

Airmerge blenders can be designed for batch or continuous operation to meet your requirements.

This system is low maintenance, simple to operate and achieves complete cleanout.

Column blender

For materials that are more difficult to blend, we recommend the column blender. It uses a ‘fountain flow’ technique to give a radial circulation capable of blending ultrafine powders, coarser sandy materials and products with a wide particle size distribution. Air enters the fully fluidized cone beneath the column, reducing the density of the material within, which is then displaced upward as the denser material from the annulus of the cone flows inward.

This simple-to operate system has no moving parts and utilises a 60˚ cone design to achieve gravity discharge. One of the biggest benefits of the design is the flexibility in particle size range. But you can also accommodate different volumetric batch sizes by dividing the central column into two or more separate pieces.

Complete reclaim. Smart design. Low maintenance

Safe, efficient discharge

Whichever silo you choose, easy discharge remains a priority. And it’s our priority too, which is why we’ve worked hard to perfect our aeration and reclaim technology. First In – First Out is our philosophy.

When product gets stuck in the silo, you have to get it out – and ultimately that can mean sending in personnel to clean up. A risky procedure best avoided at all costs. By ensuring that product is continually in motion, bridging, lumping and compaction are prevented. The silo technology and related controls do all the work for you, so your personnel aren’t in danger – and you get your materials out safely.

Flexible storage options for a range of materials

Whether you are searching for a blending silo that can deliver a more stable kiln feed, seeking a more effective means of storing and reclaiming cement, or looking to minimize the storage footprint for your range of finished products, we have the silo for you. Talk to our experts about your precise needs.

Complete reclaim

We engineer all our storage silos to maximize the benefits of fluidization while minimizing power consumption. Our Ful-Floor™ reclaim systems for dome silos use our industry-proven Airslide® fabric anchored to nearly 100% of the floor area. Embedded aeration troughs and piping eliminate restrictions that can inhibit material flow. The result? Complete reclaim of your stored material with minimal floor slope, low average power and low maintenance.

Low maintenance

Our blending and storage silos are designed with very minimal moving parts so maintenance requirements are low.

Low energy costs

Fluidizing air keeps your material moving, but we all know that the use of compressed air can be a major expense. To keep costs low, we use minimal fluidizing air and only aerate one or two sections at a time. This also brings down your maintenance requirements. 

Easier raw meal cement processing with the Controlled Flow silo

Increasing productivity and efficiency to meet your demands


Your productivity relies on a process that handles product flow capably, reliably and efficiently. The Controlled Flow silo provides optimal flow, homogenising efficiency and significant power reduction at low investment cost. It operates continuously and is built to blend, homogenise and store cement raw meal.

Dependable kiln feed systems


Our kiln feed systems have proven short- and long-term accuracy and deliver outstanding reliability in hundreds of installations. We offer two solutions for kiln feed systems:

  • FLS Low (loss of weight) 
    This arrangement uses signals from the load cells to start and stop the process, maintaining pre-set material level limits. The kiln free flow rate is controlled by measuring the extraction rate of kiln feed by units determined by loss in tank weight per time unit while no raw meal is entering the silo. The position of the flow gate is then adjusted to maintain the pre-set rate while the kiln is filling.
  • Pfister® FRW
    The special design of this rotor weigh feeder is ideal for continuous dosing powdered bulk materials with high dosing uniformity and precision. The integration of weighing and dosing makes the Pfister® FRW easy to operate and extremely reliable, with negligible wear. High feed ranges and feed rates up to 1000 t/h can be achieved.


Programmable controls let you determine your flow rate distribution, as well as enabling you to fix the feed sequence, valve operation and aeration of the segments. The program starts and stops based on feed tank level. The Controlled Flow silo’s control panel is programmable through the kiln feed system and vice versa.



Additional design features

  • A single rotary blower aerates the kiln feed tank and operates at up to 0.8 bar of pressure.
  • For storage silos, the optimised low-height tank operates at up to 0.4 bar of pressure.
  • The bottom of the feed tank has one or more electrically or pneumatically-regulated gates that control flow – allowing you to regulate the flowrate.
  • The rotary blowers have noise-reduced blow off pipes that release fluidization air out at the correct pressure level.
  • The standard features of the silo top include manholes, sounding pipes, over- and under-pressure valves (also known as the pressure equivalizing valve), a level switch and level indicator, along with a de-dusting system. 


PDF (818KB)
PDF (365KB)
PDF (830KB)
PDF (1131KB)
PDF (543KB)
PDF (1068KB)

FLSmidth research delivers SiloSafe cement

Read Story

High-quality, SiloSafe cement

Read Story

Stories from FLSmidth