\\na.aecomnet.com\lfs\apac\christchurch-nzchc1\legacy\projects\605x\60544823\6. draft docs\6.1 reports\waihi north\app d - kinetic and column testing\appendix d - attachment a.docx 3 of 6 Waste rock should be crushed to ensure the maximum particular size is not greater than 60 mm or 20% of the column diameter. The selected waste material should be combined (ie. two groups of waste rock totally approximately 180 kg each), mixed and then divided equally between the columns (ie. approximately 60 kg of material per column). Material should then be placed directly on top of the K1 gravel. Representative samples from each column’s rock should be sent for analysis for the parameters detailed in Table 1. A minimum of 150 mm should be maintained between the top of the sample and the top of the column. Table 1. Recommended analytical suite for column waste rock PSD (Particle Size Distribution) NAG Total Sulphur (%) Total Carbon (%) ANC (kg CaCO3/tonne) Aluminium Iron Calcium Magnesium Sodium Potassium Antimony Arsenic Barium Cadmium Cobalt Chromium Copper Lead Mercury Manganese Molybdenum Nickel Selenium Vanadium Zinc Titanium Boron Strontium Thorium Tin Silver Thallium Fluoride Uranium Detection limits (where applicable) should be based on previously provided detection limits for samples representative of waste material within and adjacent to the Gladstone pit. 4.0 Initial Column Operation and Sampling Initially, columns should be left exposed to atmospheric conditions for a minimum of 6 weeks and until they became acid producing. This period ensures that material selected for the columns has time to revert from an unoxidised state at time of placement to an oxidised state.
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