Tonnage
150tph
Material
Sand & Gravel, Limestone, Crushed Rock
Output
High quality concrete sand
THE CHALLENGE
Situated in the Gulf region in Tabuk to the North West of the Kingdom of Saudi Arabia, cement producer Abdullah Abdein faced several challenges when processing material for its concrete production including processing very fine dune sands, water availability, and maximising yields from variable feedstocks.
THE SOLUTION
In 2013 CDE installed a sand washing plant which included an EvoWashTM 151 sand washing plant and an AquaCycleTM thickener.
A key factor in the success of this installation was the ability of the EvoWash to accept a combination of feed materials. This was required in this instance in order to produce the sand specification required for use in the block making factory and ready-mix production.
Due to the variation between the composition of the dune sand and crushed rock feed it was recommended that the two materials should be blended prior to processing through the EvoWash. This is because dune sand is a very fine material so if processing this material on its own the capacity of the wash plant would be reduced to approximately 120tph. Blending the two materials allows the customer to maintain the 150tph required capacity while also delivering high quality concrete sand.
The feed material is delivered to the plant dry and the EvoWash comes equipped with the additional option of a feed box mounted on the side of the sump with an integrated water inlet point. This ensures that the material is adequately fluidised before it enters the EvoWash sump. The material is then pumped to a dual cyclone arrangement via the integrated Warman slurry pump.
The cyclone underflow is discharged onto the EvoWash dewatering screen with the -63 micron material removed and is subsequently discharged to stockpile with approximately 12% moisture content.
The cyclone overflow containing the waste water and the -63 micron material is discharged to the water treatment phase which employs an AquaCycle A400 thickener. This allows for 90% of the water used during the sand washing process to be recycled to the washing plant thus reducing the volume of fresh water required to feed the plant. The AquaCycle makes sand washing possible in the Gulf’s arid environment enabling the customer to produce a high quality concrete sand.
The AquaCycle thickener works by separating the waste water from the fine material with the assistance of a flocculent. Material enters the thickener and is dosed with flocculent prepared in the integrated FlocStation unit. From here the material is delivered to the centre of the tank in order to ensure efficient settlement of the fine particles. Discharging material in the centre of the tank ensures that it is as far away from the recycled water overflow point as possible thus ensuring maximum settlement of the fine particles.
The flocculent forces the fine particles to bind together and sink to the bottom of the AquaCycle tank. The clean water overflows a weir at the perimeter and is then delivered to a holding tank before being re-circulated to the EvoWash sand washing plant. The settled sludge is conditioned for discharge via the quadrake system which ensures that the sludge is of a consistency that allows it to be pumped greater distances than would otherwise be the case.
THE RESULTS
The project was delivered in partnership with the Middle East Development Company (MEDCO) headquartered in Jeddah with a number of offices throughout the Kingdom of Saudi Arabia in Riyadh, Al-Khobar and Abha.
Mr Sameh Awny El-Hofy of MEDCO added “The EvoWash and AquaCycle in combination provides the template for how operators can introduce a washing plant to their processes in the Gulf region as it effectively tackles the issues around water availability that until now have been a major barrier.”
According to Ruchin Garg (CDE Regional Manager for MEA) the combined solution allows this operator to enjoy the efficiency gains and flexibility that the EvoWash and AquaCycle offers. “The EvoWash has been chosen on hundreds of our global installations for the simple reason that it offers the most efficient sand washing system available.”
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