• RMS-Ross Corporation
    Tel.  (604) 792-5911
  • Chilliwack, BC, Canada, V2R 4H2
    Fax.  (604) 792-7148
  • 44325 Yale Rd. West



The Derocker is ideal for alluvial mining in areas with large boulders, and can easily handle light to moderate clay with an optional high-pressure spray system. It delivers a -2" product to downstream recovery and discharges clean washed +2" rock and boulder separately.

RMS-Ross Derocker loaded for transport

Key Features 

  • Automatic, spring loaded feeder
  • Self-cleaning Grizzly Bars
  • All rocks washed thoroughly

The Derocker was developed in Canada’s historic Yukon Territory by a professional Placer Miner to overcome the problems of plugged grizzlies and effectively washing course rocks, boulders and gravel to liberate and retain the particles of gold.

The Derocker easily handles angular and slab shaped materials or boulders up to 4 feet in diameter. Unlike other systems, the greater the percentage of larger rocks and boulders, the greater yardage the Derocker will process.

RMS-Ross Derocker - section view showing operation
As the subframe moves back and forth (yellow arrows), the deck (3) undulates, causing the material (1) to move down the deck with the 2" minus dropping through the grizzly bars (purple arrows) and out the bottom to the gold recovery system, leaving the washed coarser material (2) on the top of the deck to be discharged.
SpecificationsModel 8 x 20Model 10 x 20Model 14 x 20
Fine Material Capacity *
Yards/Hour 80 100 100
(Tons per Hour) (120) (150) (150)
Average Gravel Capacity
Yards/Hour 120 - 180 150 - 200 200 - 300
(Tons per Hour) (180-270) (225-300) (300-450)
Coarse, Rocky Material Capacity
Yards/Hour 180 250 250-400
(Tons per Hour) (270) (375) (375-600)
Water Requirements* 1,000 - 1,800 GPM
3,800 - 6,800 Litres/ min
1,500 - 3,000 GPM
5,600 - 11,500 Litres/ min
2,100 - 4,000 GPM
8,000 - 15,400 Litres/ min
Operating Dimensions 8' 6" x 21'+ 10' 5" x 21'+ 14' 5" x 21'+
Shipping Dimensions 8' 6" x 21'+ 10' 5" x 21'+ 1 piece 10' 5" x 21'+
2 piece 3' x 21'+
Weight 34,000 Lb 40,500 Lb 50,500 Lb
Motor 30 Hp Electric Motor 40 Hp Electric Motor 50 Hp Electric Motor
Grizzly/ Screening Plates 400 brinell plates spaced 2” apart joined by wear-resistant pins and bushings/ or optional sealed Caterpillar pins and bushings
Hydraulics Variable volume pressure compensated pump, for adjustable automatic speed and cycle control
Options Dump box suitable for loader or dozer.
Recovery units: Sluice box, centrifuge concentrators for fine gold recovery, Jigs

* Processing capacity and water requirements vary with site conditions.

RMS-Ross Derocker Control Panel

There are a variety of dump box options available for the Derocker depending on the type and size of dozer, loader, or excavator used.

With the Derocker set on a eleven degree slope, the material to be processed is loaded into a surge pile in the upper end of the machine where a built-in Spring-Loaded Feeder evens the material flow across the deck while the loader cycles to the pit for more material.

RMS-Ross Derocker side view with high-pressure spray manifoldThe gold bearing boulders and gravels are moved across the self-cleaning grizzly bars in a wave action while being washed by high pressure from the water manifold. The coarse, rocky material is discarded from the lower end of the Derocker where it can be easily removed.

The 2" minus fines wash through the slots between the grizzly bars and are carried out the bottom to suitable gold recovery equipment (Centrifuges, Circular Jigs and Sluices, available from RMS) by the process water. The total water requirement of the system is relatively low as the sluice uses the same water that is used to wash the boulders.

RMS-Ross 10x20 Derocker with Sluice, clean-up of concentrates

RMS-Ross 10x20 Derocker in operation