. mining and engineering journal. been taken from the Chamber of Minesanalysis for the month of August, 1912. The horizontaldotted line represents the average recovery per ton milledfor the 55 properties included in the statement, but thevalues indicated on the chart do not include that of theNew Rietfontein mine, which, being on an outer series, tlic calculation—and dividing this quantity in tlie sarmanner as before we have the following results: — Toil* above average grade ... 1,1.^1,880Companies below^ average grade ... 052,000 (Ginsberg) at average grade 14,653 2,008,0
. mining and engineering journal. been taken from the Chamber of Minesanalysis for the month of August, 1912. The horizontaldotted line represents the average recovery per ton milledfor the 55 properties included in the statement, but thevalues indicated on the chart do not include that of theNew Rietfontein mine, which, being on an outer series, tlic calculation—and dividing this quantity in tlie sarmanner as before we have the following results: — Toil* above average grade ... 1,1.^1,880Companies below^ average grade ... 052,000 (Ginsberg) at average grade 14,653 2,008,032 The JMoKE these two statements it will be seen that whilethe high grade mines obtained a profit for the month equalto nearly three times that obtained by the low grade under-takings, the tonnage milled, on the other hand, is not nearlyso disproportionate. The very obvious conclusion to bedravi^n from the figures presented here is that it is to thegroup of mines which are indicated above the horizontal line. i)i.\Gn.\M Showing Ore ;i:s .\i,i I 111: \\rrw.\Ti:itsi!ANn. does not fall to be considered in this article. The averagerecovery per ton milled, it will be observed, was 28s. 9d.,with an average sorting of 1805 per cent. Of the 54 mineswhich are included in our review, 26 declared a grade abovethe average, 27 showed a grade below it, and one, theGinsberg, had a value exactly coinciding with it. The dis-tribution of the producing mines into what may be termed,roughly, high and low grade, is fairly even. The prepon-derating influence of grade upon j)rofits in this scheme ofdivison is api)arent from the fact that tiie total estimatedworking profit from 53 mines of £1,052,451 for the monthof August was thus divided bet\\ecti the contributing com-panies—the Spes Bona being cxcliulrd as not declaringany profit: — Companies al)ovc average gradeCompanies below average grade(Ginsberg) at average grade £767,079 278,045 7,327 .£1,052
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjectmineralindustries
