Samples of Silicate Rock Milling Procedures

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2.2. Materials and Methods

2.2.1. Samples of Silicate Rock

The silicate rocks used in this research were meta basalt, meta dolerite, gneiss, and K-feldspar, respectively from Bunbury, Jarrahdale, Northam, and Port Hedland, Western Australia. The bulk samples of the first three rocks were washed with deionized water, air dried, and broken with a hammer to about 1-cm diameter, ground with a steel Tema ring mill for 3 min at 760 rpm, and sieved to pass a 250 µm sieve. K-feldspar Ø 150 µm was supplied by Commercial Mineral Ltd. Perth, Western Australia, which material commercially used in ceramic bodies and glazes, and as an abrasive powder, consisting of microcline 65.6 , albite 31.2 , anorthite 0.6 , kaolinite 1.0 and free quartz 1.0 Commercial Minreral Ltd., 1997. These materials are designated as initially milled rock T0.

2.2.2 Milling Procedures

The initially milled rocks 5 g were further milled with a ball mill Spex- 8000 using a 80cm 3 steel vial and 50 g of ∅ 5mm steel balls for 10, 30, 60, 90, and 120 min. In the following discussion, milling times will be denoted as T0, T10, T30, T60, T90, and T120. For wet milling, 15 mL H 2 O was added to the samples prior to milling. Other subsamples of initially milled basalt, dolerite, and gneiss, respectively were added to reagent grade NaCl or KCl 4.5 g rock + 0.5 g NaCl or KCl and milled for 120 min under dry and wet conditions. Basalt and dolerite T0 were also mixed with K-feldspar at a ratio of 1 : 1 and milled for 120 min under dry and wet conditions. The adhered rock powders on the mill vial were scratched with a stainless steel spatula, and for those on mill balls were removed by hand shaking the balls using stainless steel screen. All of these powders were transferred to plastic containers for storage. The wet-milled samples were removed from the mill vial and ball surfaces using a DI-spray bottle, and were transferred to plastic bottles through plastic panels equipped with a stainless steel screen. The suspensions of the wet- milled rocks were centrifuged for 10 min at 11,000 rpm using Eppendorf 5810 Centrifuge maximum capacity of 4 x 1.1 kg and speed 12,000 rpm, the supernatant was discharged and the powders were oven dried at 60 o C for 48 h and placed in plastic containers for storage. 7

2.2.3 Analytical Methods