The Little Sandy Desert region, within which the LD Project is located, is underlain by the Savory Basin.

The shallow sediments of the Savory and southwestern Yeneena Basins generally comprise gently eastdipping medium to coarse-grained sandstone and pebbly conglomerate. The underlying bedrock outcrops infrequently: more than 90% of the basin is covered by unconsolidated or semi-consolidated Cainozoic deposits, consisting largely of windblown sands in the form of dunes and sandplains (Williams, 1992). The sand is composed of medium to medium-coarse quartz grains, with occasional ferruginised grains or ironstone pebbles. The wide-spread longitudinal dunes that occur throughout the Savory Basin are thought to have formed during the intensely arid conditions that prevailed during the last glacial maximum. Colluvial deposits occur to a limited extent in the Basin and are mostly located adjacent to infrequent rocky outcrops. Alluvial deposits of unconsolidated silt, sand and gravel are also relatively uncommon and are restricted mostly to drainage lines and to the terminal Lake Disappointment playa.

The superficial sequences are underlain at variable depth by members of the Neoproterozoic Tarcunyah Group, which comprises an interbedded sequence of sandstone, siltstone and shale deposited around 800 Ma. These bedrock materials outcrop locally to the east and the south-west of LD.

The stratigraphy beneath and adjacent to LD reported in published literature has been generally confirmed by Reward’s explorations programs. Subsurface conditions beneath the playa comprise windblown silty or clayey sands, interspersed with – and underlain by – clayey / silty lake sediment (lacustrine) deposits, with occasional sandy lenses.

The project will extract brine from the surface of the playa via infiltration trenches and then be moved from the infiltration trenches to the main feed channel and then into a series of evaporation ponds.

The total length of the initial trench system will be approximately 133 km including 116 km of infiltration trenches. These will be relatively shallow at around 1.8 m which is 0.5 m below the nominal base of the gypsum sand layer, although further tests are being conducted on deeper trenches.

Excavators (30 t machines with 15 m reach and amphibious tracks) will operate on a permanent basis for ongoing trench maintenance to ensure that they remain in an open, free flowing condition. The material from trench excavation will be used to construct road bunds and flood protection bunds alongside the trenches.

The brine from the infiltration trenches will flow into the plant feed channel and then onto the halite ponds at the start of the brine evaporation system. The feed channel will be 6 m wide and 2.5 m deep at the start in the infiltration area and gradually increase in depth along the 16.3 km distance from the trenches to the corner of the halite pond area.

Kainite Crushing and Milling
Kainite solids reclaimed to the process plant will discharge into a kainite feed bin to allow for steady flow into the plant. The kainite feeder discharges into a sizer which reduces the feed size to a P95 of 50mm. The solids are then further reduced in size in a conventional ball mill in closed circuit.

The ball mill will be operated with 100 mm media and a coarse grate aperture of approximately 80-90 mm to minimise over grinding.

The evaporation ponds will initially crystallise raw salt and ultimately crude potash salts (predominantly kainite). The crystallised crude potash salts will be dry-harvested and trucked to the process plant for further treatment.

The ponds form an integral part of the brine processing system. The primary components of the production ponds are as follows:

- Infiltration trenches – extract brine from the playa.
- Plant feed channel – transfers brine from the infiltration trenches to the evaporation ponds.
- Halite ponds – used to concentrate brine and crystallise primarily halite.
- Back-mix ponds – crystallise halite and various additional salts prior to potassium crystallisation.
- Crystallisation ponds – designed to produce crude potash salts for harvest, prior to transport to the plant for SOP recovery.
- Halite salt stacks – will store halite generated in the halite and back-mix ponds.
- Plant bleed pond – after about 10 ye ........