Tarmac – Shireoak case study

Material source:

50/50 split between gravel and fine sand

Equipment installed:

  • Commander 1400 10x5 2 deck full rinser
  • Powerscrub 120R
  • Finesmaster 120
  • Commander 1400 10x5 2 deck part rinser
  • 6 T5032 conveyors
  • Pegson cone crusher
  • Caterpillar genset

Project requirements:

Bunter sand deposit Tarmac Shireoak needed to process sand and gravel raw material containing a very fine sand content. Typically, 30% of the material passes the 300mm sieve and 7% of the raw material presents as silt.
Successful production of the 20-5mm gravel product was considered essential, as it’s the grade most customers need for concrete, however to achieve the correct specification, the Tarmac Shireoak plant needed to remove some of the 10mm product.

Duo’s solution:

In devising a plant where hopper loaded material could subsequently be washed by the Commander 1400 to produce 0-3mm sand, 0-6mm sand (using a split bottom deck), a midsize 6-20mm and an oversize (+20mm); the designed Duo system could successfully enable sand slurries to be piped to the Finesmaster, before being dewatered and having the fines recovered and stockpiled.

The system would enable oversize product to be crushed and fed back to the primary Commander and midsize material could be scrubbed of clay in the Powerscrub 120R, before a secondary screen rinse and grading to the required 10 and 20mm products.

Project success:

The Powerscreen wash plant is producing 4 grades of high-quality clean aggregate. The Finesmaster 120 with its combination of bucket wheel and twin hydro cyclone sand recover systems means that fine sand losses to the ponds are minimised thus maximising production of saleable product. In addition, the second screen process, using a 2-deck box system and a variety of modular mats brings the 20-5mm gravel product within the required spec. As such, a tonnage: 200,000 TPY, 100 TPH + recirculated material from the crusher, is successfully producing building sand to BS1200, concrete sand to BS882, 10mm stone and 5-20mm stone.