Presentation of the project
MS has been asked by the company Aggregates Oued Cherrat (AOC) in 2012 to deal with problematic of recomposition of sand and treatment of water. This company produced 0-5 mm sand and in a constant concern for quality, Aggregates Oued Cherrat wanted to value it, producing 2 fractions in order to recompose the sand and follow a specific grainsize.
Both fractions were composed of a fine 0/1 mm sand and coarse 1/5 mm sand with a feed of 100 t/h. 0/5 sand contained about 10% of fine particles < 63 mm.
Aggregates Oued Cherrat wanted also to establish downstream, a water treatment plant allowing to recycle sewage water containing fine particles < 63 mm and to use this water in closed-circuit.
MS thanks to its know-how in solutions of liquid/solid separation, guided exchanges with AOC team and suggested this innovative concept: design, manufacture and install a grainsize correction unit and a water treatment plant which will be put together in the best possible way on site.
Technical challenges and provided solutions
In the light of the specifications of the client and the tests carried out in our laboratory, we recommended:
- A first cut to 1.5 mm using a cyclonic sifter with dewatering of the coarse fraction (1.5-5 mm)
- A 2nd cut to 63 μm of the fine fraction by cycloning (single stage) followed by a dewatering of the cyclone underflows (0-1, 5 mm)
- Recycling of sewage water containing fine particles < 63 μm (by flocculation) for a closed circuit use.
- Concentration of dry solids into a liquid sludge stored in basin.
Regarding the phase of sand treatment, we provided a grainsize correction unit (MCC 100) with 200 m3/h of water. This equipment allows to produce both required fractions and recompose sand through automatic flaps. This system enables the plant user to completely control the grainsize distribution (fineness modulus) and the stability of one specific sand production envelope.
The clayey sand and the washing water are treated in a compact unit enabling to combine the washing of the sand (through an hydro cyclone) with a grainsize correction according to the following principle :
- cut at 1 mm with a cyclonic sifter to create 2 fractions (so called 0-1 mm and 1-4 mm)
- cycloning of the fine fraction to remove the fines < 63 µm
- dewatering of the 2 fractions
- production of a recombined sand from the 2 fractions
Cyclonic sifter (MS Patent)
Functionning of the grainsize correction unit
Regarding the phase of water treatment, we provided a water treatment plant (DR8/20) receiving sewage water from the washing process, with as dual purpose to clarify the water and concentrate sludge using the principle of flocculation.
This water treatment plant include a settling tank with peripheral overflow channel, a pendular scraper with a raising and driving mechanism, a control room (including Dosafloc and Controfloc units), a recycled water tank, a sludge pump and a water pump.
The technical study of these two phases represented 46 specific plans and 230 hours of design study.
Delivery and assembly on site
For this project, the whole plant was pre-assembled and pre-wired in our workshop, thus ensuring a fast and easy erection, as well as a more efficient commissioning on site.
Pre-assembly in our workshop
Departure from our workshop
Commissioning on site
Moreover, in order to convey the image of our client, we customized the control room according to grahic charter of AOC Company.