THE PROJECT
NEYRTEC MINERAL was involved in this solid rock quarry in Brittany, near Brest. The operator called on our team to treat the sludge produced by washing water from the sand and aggregates processing plant. The washing waters were sent directly into the filling pits, and the customer needed to find an economical solution to reduce the volume of sludge stored. NEYRTEC MINERAL proposed a decanter with a polymer preparation unit, complemented by a sludge pump and a water tank.
NEYRTEC MINERAL SOLUTION
To reduce the volume of sludge stored in washing water reception pits, NEYRTEC MINERAL designs and manufactures a custom-designed 14-meter-diameter decanter that ensures separate separation of water and sludge. The decanter is sized according to the quarry’s water flow rate, i.e. 370 m3/h. The thickened, recovered sludge is scraped from the bottom of the decanter and pumped to a sludge tank. A powerful pump transfers the sludge over a length of 500 metres and 26 metres of positive gradient. The flow of wash water fluctuates considerably depending on the wash program (sand/chips).
Next to the thickener, NEYRTEC MINERAL installs a water tank to recover clarified water, which will be reused for washing sand and aggregates upstream.
A polymer preparation unit (1m3) prepares the flocculant solution and adjusts dosage and distribution according to the mineral load and flow rate of the water to be clarified. Flocculent accelerates sedimentation speed, improves water clarification and promotes sludge thickening.
PERFORMANCES
With the commissioning of the thickener and polymer preparation unit (main equipment within the NEYRTEC MINERAL range), the quarry washed waters are treated at a flow rate of 370 m3/h. Sludge leaving the decanter has a minimum concentration of 650 g/L. The sludge discharge is located 26 meters above the decanter.
FIND OUT MORE ABOUT AGGREGATES
Aggregates have 3 origins: those from crushed rock are angular, those from alluvial deposits are rounded (or rolled, like pebbles) and artificial granular materials. Also known as aggregates, they are used in the composition of various bound and unbound materials. These are essential elements in the planning, construction and public works sectors.
Their nature, shape and characteristics vary according to deposits and production techniques. Three categories of aggregates can be distinguished: alluvial aggregates, which account for around 40% of total production; solid rock aggregates (eruptive and limestone), which account for 30%; and recycled aggregates, also known as limestone, which account for 25%. They are produced in different grain sizes ranging from 0 to 125 mm.
In France, the annual consumption of aggregates is 350 million tonnes, or 6 tonnes per inhabitant per year, making it one of the most widely exploited resources.
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