1973 Summary and Procedures Report AP2288 Frances Creek

Abstract

Nine of the twenty two ore bodies have been drill tested to some degree in the 1973 programme. Jasmine Central for example has been tested by one hole, Helene 6/7 by 60 holes. The nine deposits tested constitute those containing 74.6% of the ore in numbers 1-19. We have in addition made a study of the old drill results on all deposits and have made an independent assessment of reserves. We have found survey errors in some of the old grid systems and holes misplotted. There are, however, sufficient holes in all deposits (even though we may not agree with their siting) to enable our reserve estimates derived from them, to be categorised into proven and probable. This subdivision is based as close as possible to the recommendations made by The Australasian Institute of Mining and Metallurgy in 1971. It will be that when mining commences on some deposits that the predicted ore outlines (say on a week to week basis) will not be as predicted. For this reason it is imperative that pre-production drilling he done to facilitate forward production scheduling. Recommendations for this work are attached where applicable to individual reports. Drill programme of a fill in nature are also appended. Proved Ore - Drill testing was concentrated within the pit outlines designed by FIMCO personnel. Only ore grade material within a pit may appear in the proved ore category - despite the fact that similar type material may be just outside the pit design. In deposits with no current pit design (e.g Jasmine West, Helene 4), proved ore specification is based solely on grade and drill hole density.

Possible Ore - In nearly all cases ore continues below and, beyond the pit design and some deep dri11 holes have tested this area. The ore outside the pit confines, for the sake of uniformity may only fall within the possible category. Sometimes a total figure can be given for this probable ore, at other times it is possible to calculate only a tons per vertical foot figure. Both or either of tons per vertical foot is quoted in the individual deposit reports. It is appreciated that much of this ore will be recoverable by improving pit design and extraction techniques. Unwashed Pines Stockpile - Figures are supplied by mine staff and are current to 17/9/1973. Stockpile survey was made in July 1973 by a contract surveyor and measured 425,000 tons. Conversion factor 171 lbs per cubic foot. Mine records show that 19,967 tons have been added since July. No allowance has been made in this figure for saleable recovery. Methods - All reserves have been calculated using assays plotted on drill sections. The area of influence of the grade in any one hole is assumed to extend half way to the adjacent hole. These areas of influence were measured by planimeter and multiplied by half the distance between adjacent sections, to derive a volume figure for the ore block. The individual volumes were then weighted against iron grade to obtain an over all grade for the deposit. The appropriate cubic feet per ton factor was then applied and a tonnage figure derived. Geological interpretation of rock types, figures largely in the shape of ore blocks in Helene 6/7 - all other deposits rely almost solely on assays cutoffs. Occasionally, in Helene 6/7, narrow hands ( 10 feet) of 50-60% Fe material have been included in high grade reserves. All drilling and assay results from the 1973 programme have been used in calculating reserve figures and all appear on the appropriate sections. Old drill results are used where appropriate. The old drill sections are appended to the deposit reports, together with the new, for purposes of comparison. Ore contacts in the various pits have been picked up wherever possible and used refine the ore shapes obtained from drilling.