Australian Potash Limited (APC) provided a summary comparison of the Lake Wells Sulphate of Potash Project (LSOP), 160 kilometres north-east of Laverton in the north-eastern Goldfields of Western Australia. The early works program has focussed on progressively reducing development risk. Key aspects in this phase are: Lake Wells is a 100% borefield Sulphate of Potash project with zero kilometres of trench abstraction.

Being developed without any recourse to a trenching system to abstract, or mine, the potassium rich brines makes the Lake Wells project unique amongst its peers. 20 bores of the 79 bores required in steady state operations have been drilled. Brine volume flow rates and grade in test-pumping in line with Hydrogeological (Reserve) model.

The Lake Wells' evaporation network comprises on-lake pre-concentration ponds and off-lake, HDPE lined harvest ponds. 460 geotechnical test-sites sampled across the surface of the lake system have identified a consistent layer of clay preventing vertical seepage of brine. The pre-concentration pond construction methods were trialled and demonstrated the veracity of the LSOP pond construction design.

Evaporation pond development does not rely on long transfer pipelines or trenches of pre-concentrated brine. The Lake Wells' processing design is based on the reliable and proven North American flow sheet with direct schoenite flotation and belt filters. LSOP flow sheet has been used successfully at the largest ex-China solar SOP producer for over 50 years.

Several contemporary developments using similar flow sheet design have commissioned successfully and transitioned to profitable operations. The Lake Wells' processing plant will be contracted on an EPC basis providing process, time and cost guarantees from a successful Western Australian engineering head contractor. Preferred engineering contractor GR Engineering Services Limited (ASX: GNG) is a specialist EPC contracting firm with exposure and experience to the SOP sector.

Lake Wells SOP Project is shovel ready. Progress: Prior to mobilisation of equipment for the first phase production bore drilling program, APC had developed several bores at Lake Wells. Three of these are considered suitable to take forward into operations.

Through the first phase program a further 17 bores have been developed, bringing to 20 the number of brine production bores at Lake Wells that will be utilised during start up and continue through steady state operations. On a linear basis this represents the development of over 25% of the LSOP's borefield: but on a volume basis the bores developed to date account for approximately 35% of required brine flow for full scale production. Evaporation network: All of the potash projects being proposed in Western Australia are brine based `solar salt' projects.

The critical step in these operations is allowing sufficient start up time to manage the evaporation and subsequent crystallisation of the various salt species present in the brines: the target salts are the potassium bearing ones. Failure to manage an appropriate brine flow has knock-on impacts to the evaporation network, as the only way to slow down the evaporation of the brine in the network is to add more brine: weather conditions cannot be changed. The Lake Wells' operating model includes a buffer pond at the start of the network, which will be fed year round from the borefield.

The purpose of the buffer pond is to enable the storage of brine supply during the low evaporation periods (winter), that can then be discharged at a greater rate than is possible from the borefield directly, in the peak evaporation periods (summer) to better manage the pre-concentration ponds, to ensure they do not dry out and that the correct chemistry is maintained. The buffer pond fluctuates between 0.5m - 3.5m of brine depth and will hold, at peak capacity, up to 25% of the total annual LSOP brine demand. Progress: Thorough testwork across select aspects of the evaporation model is continuous and ongoing with the next sequence of work, currently underway in Australia and the US, comprising: Additional evaporation trials to map the ionic chemistry as the brine vaporates, which testwork is informed by additional data from the bores completed in the first phase program; Analysing and reviewing the expected solid salts composition from the harvest ponds; Translating harvest pond salt composition to the Veolia package to complete confirmatory testwork on the flow sheet, based on design values provided by Novopro; and Completing crushing testwork to size equipment.

Processing Plant: In line with adopting a `risk-reduction' approach to the LSOP development, a strategic decision was made early in 2015 to pursue and adopt an accepted processing methodology with ample evidence of success. To that end, through consulting processing engineers Novopro, who are based in Quebec and who consult extensively across North America and the Middle-East, the LSOP will be developed using a tried and tested flow sheet similar to those currently in operation in the US at three potash operations, in Egypt, Jordan and Israel. In addition, as APC is not reliant on debt or equity funding through any other sovereign export financing body, but instead has credit approved facilities with Australian institutions, the LSOP is not beholden to purchasing either technology or equipment that does not suit its purposes completely and without compromise.