proposed Solution for FFT Problem

This sketch shows an embodiment of our Trident Unit (US Patent 8,419,316) convenient to over-water deployment; the dry-land equipment is portrayed in the "Trident Unit" link below.

The following is how we envision our ground improvement tool being used for this specific task:

With the pokers and pressure input pipe in their withdrawn positions, the buoyant Trident harness would be floated over a location selected for being underlain by coarse tailings in a loose state. The pokers and pressure pipe would then be deployed to a predetermined depth.

The pokers would be activated as drains and remain extended while the pressure pipe would extrude FFT into the surrounding coarse tails. The discharge level of the pressure pipe would be withdrawn at a specified rate till it approached the surface of the tails.

It is very important to keep in mind that introducing high pressure at a point within a tailings pond, where the surrounding slope is only marginally stable, could trigger a regional slope failure. In this proposal that fear is eliminated because such a pressure point is safely encompassed within a drainage system (pokers) which can easily overpower it. So, at no time would this process endanger surrounding tailings slopes.

Following the FFT extrusion process, and the removal of the pressure pipe, the vibratory modules of the pokers would be activated while they were being gradually withdrawn. The increase in soil-structure compaction of the coarse tails thereby attained would result in bringing the pressure of those solid particles to bear on the FFT within the former voids of the host material. Any prospect of promoting consolidation of the entrained FFT would thereby have been given an opportunity to help.

This two-staged process is designed to have two separate & complimentary beneficial affects:

1. Getting rid of the FFT, essentially just by putting it back again where it came from . . .

2. Recovering the water entombed in the voids of the coarse tailings.

William E. Hodge, July 30th 2015