Managing director John Bird entered discussions early with CDE to achieve a complete lignite-removal solution, ultimately resulting in the company’s 170 tonnes/h installation.
The dumptruck feed hopper (40-tonne capacity) is fed via an access ramp. Its heavy-duty design and 6in tipping grid accepts ‘as-dug’ material while removing excess oversize. Feed is then conveyed to a twin-deck R2M108 (20ft x 6ft) rinsing screen. This separates oversize, intermediate aggregate and sand.
The oversize is stockpiled while the –5mm slurry passes to a CDE MultiSands plant. The Multi-Sands plant comprises two CDE counter-flow classification units (CFCUs) fitted with sieve bends, and three hydrocyclones. The CFCUs separate sand at 250 microns, overflowing fine particles and lignite from the main sand fraction. PLC-controlled pneumatic pinch valves control the flow of sand from these units to two integrated C-Series quick-dry, high-frequency dewatering screens.
Finer cutpoints are achieved with the cyclones; these are specified according to the flow volumes at different stages in the system and have effective silt separation points from 75 mircons to 40 microns.