Granite iron extraction

Extraction of Inactive Coupons with KTOX Solution. Average iron extraction rates are plotted as a function of cumulative extraction time in Figure 2. Where rates for the altered and unaltered granite differ, the confidence level at which the difference is significant is indicated in brackets. 

The iron extraction rates for both fresh and altered granite decrease for the first 24 h and become the same constant rate for the remaining 24 to 120 h. Thus the iron associated with oxyhydroxides (formed during recent exposure to GGW or during hydro-thermal alteration) is removed during the first 24-h exposure to... 

Figure 2. Average iron extraction rates for fresh and altered Lac Du Bonnet granite as a function of cumulative extraction time.

During the first six hours of extraction, more iron is removed from the altered granite than from the fresh granite. The extra iron from the altered granite is believed to be that associated with the production of iron oxyhydroxides during the 101-d exposure of the granite to GGW. 

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