Engineered For Your Success

Treatment of sand
and gravel washing water

Reduce the need for fresh water by 90%

Decanter centrifuges for recovery of wash water in sand and gravel mills.

Sustainable use of water as a resource and stronger regulations call for an intelligent and simple solution to recycle existing process water. When treating sand and gravel, Flottweg industrial centrifuges drain the sludge from wet treatment. The reclaimed water can then be returned to the process. 

The treatment of sand and gravel requires a lot of water. The sludge separated in wet treatment is often temporarily stored in lagoons or ponds. The ponds serve as water reservoirs and sedimentation tanks. Over time, the solid sediments and settles on the bottom of the pond. The clear water is extracted and fed back into the process. Gradually, more and more sediment accumulates on the bottom of the pond. The usable volume of the pond is reduced and less water can be stored. The pond therefore has to be excavated regularly at a high cost. Mountain regions also make it more difficult to set up lagoons as there is less space available. Decanter centrifuges for sludge dewatering separate the fine solids from the water. The clear water can be stored in a washing water reservoir and is immediately available to the washing process again. There is no need to maintain sedimentation ponds.

In order to prevent contamination of groundwater, water protection authorities regulate the formation of new lagoons. Decanter centrifuges use centrifugal force to separate even the finest particles from the water. At the same time, the volume of the solids and thus the disposal costs are significantly reduced.

The more washing water that can be recycled, the less fresh water the sand and gravel mills need. There is a lack of water in many regions of the world. The increasing shortage is making groundwater extraction more expensive. If the existing washing water is temporarily stored in lagoons, some of the water evaporates through the large water surface. This part must be replaced with fresh water.

In addition to the machine, the efficiency of the entire process plays an important role in achieving the best results. We take over the engineering for you from project planning to the planning of complete process solutions.

Our high-performance centrifuge for the recovery of sand and gravel washing water

Water treatment with Flottweg industrial centrifuges

The washing water to be recycled flows from the wet preparation into the lamella or oblique clarifier.  The sludge deposited there is pumped directly into the decanter centrifuge for sludge dewatering. As the centrifuge can process large quantities, interim storage in a stacking tank is generally not necessary.

The water clarified in the decanter is continuously returned to the fresh water reservoir. The dewatered solid falls into a bunker. A wheel loader or belt conveyor brings it from there to the stockpile.

During treatment, the sludge from the lamella or inclined clarifiers goes directly into the decanter centrifuge. Here it is separated into clean process water and dewatered solids. How to drain the washing water with Flottweg separation technology

Customer benefits

Sustainable management with water recycling

Flottweg systems drain the sludge from wet treatment very efficiently. The clarified water is available to the washing plant again. Depending on the process, over 90 percent of the process water can be recovered. This means that valuable groundwater hardly needs to be used for cleaning.  As it is a closed circuit, no process water is returned to the environment. Settling basins or lagoons for the used washing water are reduced or can be partially omitted.

  • Low fresh water consumption
  • Recirculation of over 90% of the processed water into the washing process (depending on the process)
  • No return of process water to the environment
  • Closed process water circuit
  • Reduction or elimination of sedimentation basins and lagoons

Reliable high-performance decanter for gravel and sand processing

Flottweg decanter centrifuges can continuously process high sludge quantities. Sand and gravel can thus be fully automatically processed in parallel operation. Designed for mining work, the machine has highly efficient wear protection on the screw and rotor. The centrifuge works as a closed system and separates even the finest solids from the washing water. Thanks to the Simp Drive® drive system, it automatically adjusts to different feed volumes and, if necessary, to fluctuating solids concentrations in the incoming sludge. A high dry matter content in the discharged solids enables  the material to be conveniently conveyed or loaded. At the same time, recycled water is clean and virtually free of solids.

  • High sewage efficiency to increase uptime of your wet treatment
  • Continuous processing of large amounts of sludge
  • Designed with high material quality and high wear protection for processing abrasive sludges  etc.
  • Low energy consumption and high flexibility under varying load conditions

Save investment and operating costs

The compact design of the Flottweg decanter centrifuge makes the construction of additional buildings or infrastructure for gravel and sand mills unnecessary. This significantly reduces investment costs. As decanter centrifuges use centrifugal force, there is no need for consumables such as filter cloths.

Flottweg decanter centrifuges are designed for use around the clock. Fully automatic operation is easy with the sensor-based Motice condition monitoring system, the intelligent screw drive Simp Drive ® and the new Ingo user interface. Hardly any personnel are required to operate the system. In addition, the cleaning cycle is omitted during the operating phase. This saves time and costs.

  • Compact design means low investment costs in steel construction and infrastructure
  • No consumables such as filter cloths etc. are necessary
  • Full operation from 8 h/day to 24/7 leads to low staff requirements
  • No cleaning cycle during the operating phase

Project handling made easy

Whether you need to expand your existing sand and gravel treatment system or need a complete turnkey solution for water treatment: We can handle the entire project on request. Depending on the process, we integrate our decanter centrifuge into existing processes or supply further equipment, such as fresh water storage tanks, conveyor belts, etc. After consultation, we act as the sole contact for our customers and take care of all necessary construction and mechanical measures. Our engineers have many years of experience in designing machines and systems for the treatment of sand and gravel. We are there to support you as a reliable partner throughout the entire project and beyond.

  • Flottweg can handle the entire project on request
  • Integration into existing processes 
  • On request, delivery and integration of further equipment (individual engineering) and works
  • Flottweg know-how and experience

320 m³/h fresh water saved in the treatment of washing water

The Reithelshöfer GmbH sand distribution and management company has been relying on Flottweg since June 2003. The decanter centrifuge is used in the treatment of sand washing water. 

The system consists of two components: sand treatment and washing water treatment. Flottweg decanter centrifuge Z92 has been in use for 17 years. The purified wash water is returned to the system. As a result, the sand mill was able to reduce the fresh water requirement from 350 m³/h to around 20 m³/h. Learn more about the results in this video!


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