Following the success of the new plant at Norton Bottoms, Breedon Aggregates (now Breedon Southern) ordered new equipment to modify the existing sand washing plant at Astley Moss, Greater Manchester.
The plant is situated very close to the former Astley Green Colliery and the site of Alexander Russell coal recovery plant.
The coal recovery plant, built in 1988, also used Hydrosizers but configured to produce a clean coal.
The new equipment was installed together with major modifications to upgrade the existing under-performing sand plant.
The modifications have proved to be successful and the plant is now achieving the required rate of production with correct grades of sand whilst removing lignite from the sand products.
Lignite is a contaminant contained within the raw material which, in the past, has caused major problems for the operator and has been a barrier to sales from the plant.
The contract included the full process design, transportation to site, installation and commissioning.
The Process
The process was designed to handle up to 150 t/h of < 5 mm sand and produce decontaminated concrete and building sands. The existing ability to produce a cable sand was retained.
The sand and water slurry is pumped using an existing slurry pump to new and repositioned Primary Cyclones where it is partially dewatered and de-slimed.
The underflow from the Primary Cyclones report to the Primary TBS 2400 Hydrosizer and the overflow is available for balancing the primary sump. Excess reports to the effluent sump.
The Primary TBS 2400 Hydrosizer separates the sand at approximately 0.30 mm, clean coarse sand particles discharge to the existing concrete sand de-watering screen. The fine particles, together with lignite, pass over the existing sieve bend.
The coarse lignite is rejected by the sieve bend and passes directly to the effluent sump. The fines and water report to the secondary sump where it is pumped to the new Secondary Cyclone where it is partially dewatered.
The underflow from the Secondary Cyclone reports to the Secondary TBS 2400 Hydrosizer. The overflow being available for balancing the secondary sump with excess reporting to the effluent sump.
The Secondary TBS 2400 Hydrosizer separates the remaining lignite from the sand with the clean fine sand discharging to a splitter box where it is divided between the concrete and building sand screens.
The sand products are dewatered using the existing inclined sand screens and stockpiled using existing radial conveyors.
