Treatment of alluvial sand, treatment of washing water and sludge.

Client: FAMY & Cie SARL – Site of BELLEGARDE

Treatment of alluvial sand, treatment of washing water and sludge.

Presentation of the project

 

The company Famy operates in the department of Ain, with a dozen quarries supplying materials to their own worksites and major regional projects. Famy activity revolves currently around three main activities, namely public works, quarries and construction equipment rental.

Famy operates near Bellegarde, on the quarry of Lacrans (the largest of its scheme with 40 ha authorized); an alluvial deposit composed of a sandy limestone grave. The grainsize of the extracted raw  materials is 0/100-150 with 80% of 0/20.

In order to modernize the worksite, a new sand treatment unit, a water treatment plant and a sludge dehydration unit entirely designed by MS were installed in 2010. The sludge dehydration plant is a singularity of the site because we designed and installed two 10.8 m3 filter presses, the largest ever designed by MS.

Technicals challenges and provided solutions

Famy asked MS to design, downstream Metso crushing/screening installation, a sand treatment plant able to value 250 t/h of 0/4 mm sand while ensuring washing of materials with a water recycling in closed circuit (total capacity: 1000 m3/h of water) and a sludge dehydration unit to convert 40 t/h of dry solid from sludge to dried shoveled cakes.

The entire project was subject to two technical constraints, namely:

  • The variation in the percentage of sand in raw materials, which can saturate the cyclone if the percentage is too high.
  • A rate of clay to high, which increase flocculant consumption and decrease efficiency of sludge dehydration.

In response to the technical specifications, MS designed and manufactured a complete sand, water and slurry treatment plant:

Sand treatment unit

 

 

 

0/4 sand (about 250 t/h representing 45% of raw materials) with process water (about 1000 m3/h) are recovered in tanks under the screens. From these tanks, pulp (water + sand) is taken up by a pump to be treated in two cyclones. 0/4 sand from the underflow of both cyclones is dewatering on a vibrating dewatering screen before being stored. Process water with residual sand from the second screen are also recovered in a tank under the screen and pumped to a third cyclone of which underflow also falls onto the vibrating dewatering screen. Sandy water from overflow of the three cyclones is sent to a buffer tank before the thickener. This entire unit of sand treatment is installed outside the main building.

 

 

 

 

 

 

 

 MS Sand treatment unit with 3 cyclones

Process water treatment plant

 

Process water from the buffer tank is sent to a thickener DR16 (16 m of diameter) in order to clarify water and concentrate sludge with addition of flocculant solution dosed and injected automatically. MS thickeners include all recent improvements in flocculation box, flocculation controller and scraper. A technical bungalow including flocculant preparation unit, controlfloc and electrical cabinet is installed on the bridge of the thickener.

Clarified water from the thickener overflow is discharged into water recovery tank. Two water pumps feed washing process in closed circuit from this tank and two slurry pumps transfer slurries from the bottom of the thickener to two buffer silos.This water treatment unit is installed inside the main building

 

 

 

Thickener MS DR16

Sludge dehydration unit

 

 

 

Concentrated sludge is stored in two buffer silos, which allow to regulate alimentation of the two filter presses FP15. Each with a capacity of 10,8 m3, they are the most largest filter presses ever designed by MS.

A lime milk preparation unit with a silo of lime comes as necessary supplement in case of sludge difficult to treat. Each filter press treat up to 30 t/h of sludge converted to dehydrate cakes by pressing. These cakes fall by gravity into two separate storage spaces and then are loaded in truck. Filtrates are sent to the thickener. The whole pressing unit is controlled by PLC with touch screen to display the synoptic and to give access to the settings.

 

 

 

 

 

 

 

Filter press MS FP15

Delivery and assembly on site

These units described previously were pre-assembled and pre-wired in our workshop, thus ensuring a fast and easy erection, as well as a more efficient commissioning on the site of GAMA.

Filter press departure from our workshop 

Filter press delivery on site


Filter press assembly on site

Conclusion

The extent of this project, its technical constraints and the commissioning of these two 10.8 m3 filter presses have made a feature of the site of FAMY and a flagship project for MS. This installation works with satisfaction about the performance, the quality of the sand and mud that the operator is now trying to value.

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