CDE has recently commissioned a new wash plant for C.O. Williams to process material from an existing crushing operation at Lear’s Quarry in Barbados.
The company operates a 250 tonnes per hour crushing plant processing coral limestone. This produces over 35,000 tonnes of aggregates per month and the company also produces more than 18,000 tonnes of asphalt per year.
The existing crushing plant produces a large quantity of minus 6mm material with very high fines content and as a result this material was stockpiled as a waste product on site.
“The waste from the crushing operations was an ongoing concern for us and the high fines content required that we look at a wash plant to see if we could recover any material which could be used either as construction sands or in our own asphalt production” explains Neil Weekes, General Manager at C.O. Williams.
There are waste stockpiles approaching 500,000 tons of the minus 6mm material to be processed using the CDE wash plant and the crushing plant produces another 500 tons per day of this material. An analysis of the waste stockpiles revealed a material with 20% minus 63 micron.
A further sieve analysis revealed that the feed to the sand washing plant (minus 2.4mm) would contain 36% minus 63 micron material. This required a customised double pass washing system to ensure this would be reduced to a level that would allow the washed sand products to have a commercial application.
The space available on site was also limited and access to the volumes of water required to feed a wash plant to do this job satisfactorily was also an issue. Taking all of this into consideration CDE designed a project that includes the M2500 mobile washing plant with the required customised dual pass sand washing system.
The plant also includes closed circuit water recycling with the introduction of an AquaCycle A400 thickener and a side beam filter press.
The final plant measures 45m x 29m and as a result of the inclusion of the side beam filter press has eliminated the requirement for settling ponds.
“Without the introduction of the AquaCycle thickener and filter press this project just would not have been possible” explains Neil Weekes. ”The space we had available at Lear’s quarry was very restricting and it is only the compact, modular nature of the CDE design that allows us to generate value from existing waste stockpiles and ensure that in future we are able to deal with the minus 6mm material from our crushing operations in an efficient manner.”
The new wash plant is producing a range of products which C.O. Williams are using in a number of different applications – a 2.4mm to 6mm material is being used in concrete production as is the 63 micron to 2.4mm sand product. The 2.4mm to 6mm material is also being used in asphalt production. The 63 micron to 1.2mm washed sand is used in masonry processes for block work and plastering.