Karinga Lakes Potash Project, NT

Overview

The Karinga Lakes Project covers a chain of dry salt lakes along the Lasseter Highway between Alice Springs and Uluru. It is part of the Central Australian Groundwater Discharge Zone. The Verdant Minerals JV has defined a potash brine resource beneath the dry playa lakes. These brines could be used for the production of various fertiliser minerals. The water-soluble potassium-bearing mineral salts, loosely called "potash", include potassium sulfate (sulfate of potash, SOP which is usually a manufactured product) and potassium magnesium sulfate (schoenite or leonite). Schoenite can be obtained from the Karinga salt lake brines via solar evaporation in ponds and/or flotation processing. Other by-products are also being investigated.

Karinga Lakes Titles

Karinga titles as of 30 June 2016 showing all sampling to date, including in areas now relinquished. Drilling (blue dots), shovel sampling (red crosses) and trenches (blue symbols, not to scale). JORC resource shown in pale blue. Pastoral lease in green and Aboriginal land in yellow. The Karinga Lakes titles abut Lake Amadeus in the west.

SOP and schoenite are utilised as high-end fertiliser products globally, as they have a lower salt index than other forms of potash and are often preferred in crops sensitive to chloride or susceptible to fertiliser burn. SOP and schoenite attract premium pricing in comparison to the more common varieties of potash. The Karinga Lakes Project is strategically well located adjacent to the Lasseter Highway and within close proximity of the Central Australian Railway line, providing access north to the port of Darwin and proximity to Asian markets and south to domestic markets. Moreover, Australia currently imports all of its potash requirements.

Resource Drilling

The JV has undertaken sonic and aircore drilling and flow testing over a number of years.

aircore flow testing

Aircore drilling at Karinga Lakes Potash project.

Flow testing of bores.

Hydrology

The subsurface brines in the Karinga Lakes are derived from, and replenished by, discharge of the Central Australian Groundwater Discharge Zone.

central australia

flow testing

Central Australian Groundwater Discharge Zone.

Hydrology of the groundwater flowpath.

Karinga Lakes Resource

Karinga Lakes brine potash resource estimate is 8.4 million tonnes K2SO4 including over 70% in the Measured and Indicated category.

Table 1. Karinga Lakes Brine Resource (entries have been rounded)

Resource Category

Potassium

(tonnes)

K2SO4

(tonnes)

Schoenite

(tonnes)

Measured

2,600,000

5,800,000

13,000,000

Indicated

210,000

460,000

1,100,000

Inferred

950,000

2,100,000

4,900,000

Total

3,800,000

8,400,000

19,000,000

 

 

The Karinga Lakes Potash Resource is a brine hosted resource. The potassium is dissolved in brines that are contained in aquifers below the dry salt lake surface. The JORC code was not designed for use in connection with minerals that are dissolved in brines. It is generally accepted that geological uncertainties are greater when dealing with the estimation of brine resources.

The sulfate of potash tonnage represents the in-situ brine with no recovery factor applied. It will not be possible to extract all of the contained brine by pumping of trenching; the amount which can be extracted depends on many factors including the permeability of the sediments, the drainable porosity, and the recharge dynamics of the aquifers.

The total resource is contained beneath 25 lakes with a total area of 132 km2. The average thickness of the identified resource is 17 m.

The potash brine resource is based on data acquired over four years, including;

  • 93 brine samples from hand dug pits
  • 4 small backhoe trenches which were pump tested
  • 8 vibracore drill holes
  • 73 sonic drill holes
  • 200 aircore drill holes
  • 42 installed 50 mm piezometers around drill holes and 48 piezometers around trenches
  • 47 installed 100 mm wells
  • 10 pumping tests from 100 mm wells
  • 4 long term pump tests from 3 trenches and a well
  • 142 porosity samples

 

 Karinga Lakes Potash Project Scoping Study

Verdant Minerals Ltd is pleased to announce the completion of the Karinga Lakes Potash Project Scoping Study. The baseline knowledge and understanding of the chemical and physical properties of the brine resource, technical brine extraction, evaporation, mechanical processing, logistics, regional markets and pricing, now provides a basis for formal discussions with potential development and off take partners.

Partners will likely be required to fund a bankable feasibility study on an initial development of Karinga and further exploration of the other salt lakes in the portfolio. With almost all of the potassium needs of Australia, New Zealand and southern Asia met by imports, the potential evolution of a sulphate of potash industry in Australia could create significant value over time.

A review of the extractable brine resource, chemical composition and processing analytics, process flow sheet design, mass balance work and general brine extraction and processing facility layout was completed by China International Chemical Consulting Corporation (CICCC). CICCC utilised people resources that had previously been involved in the development and expansion of the Louobopo salt lake sulphate of potash operation in North Western China. GHD Australia completed scoping study level estimates of Australian capital and operating costs, based on the CICCC design. Baseline regional market studies for both sulphate of potash and potassium magnesium sulphate were also conducted.

Two development scenarios were studied to a scoping study level of accuracy (+/- 40% capital and operating costs):

Scenario 1

  • 125,000 tonnes per annum of sulphate of potash (SOP) for a minimum of 10 years of production

Scenario 2

  • 100,000 tonnes per annum of potassium magnesium sulphate (schoenite) for a minimum of 15 years of production.

Schoenite is an intermediate product of the sulphate of potash process. Compared to SOP, Schoenite contains approximately half the amount of K2O and is therefore a lower value product than SOP. It does however contain magnesium which potentially represents a certain level of value. The Scenario 2 project is approximately one fifth the size of scenario 1 and represents the potential to develop a small scale start up, using a smaller number of lakes thus decreasing the environmental footprint and significantly lower energy usage due to lower volumes of brines being pumped smaller distances and avoiding the need to create steam that is used to convert schoenite to SOP. However, the market for schoenite as a fertiliser is less well defined than the market for SOP.

For further information regarding the Karinga Lakes Project Scoping Study please click HERE