260 
PROCEEDINGS OE SECTION E. 
several smaller mills into a larger plant under one roof would have the 
tendency not alone of lowering the cost of milling per ton of ore, 
but also of allowing the introduction of auxiliary appliances as 
rock-breakers, automatic feeders, and vanners, the adopting of which 
very often is not within the means of a smaller concern. 
In further perusal of the Annual Report of the Under Secretary 
for Mines, we find that the Queensland goldfields are credited with 
756 Berdan pans, 222 Wheeler pans, 42 Dvenny and other pans, against 
the following concentrating machinery: — 134 Brown and Stanfield’s 
concentrators, 36 percussion and shaking tables, and 76 vanners. 
It may safely be asserted that the results of the extraction would 
be greatly enhanced if the greater portion of the grinding machinery 
were to be replaced by suitable concentrating appliances. 
The Burdekin mill at Charters Towers had some twenty vanners, 
but for some reason, not quite clear to the writer, they were discarded, 
although the stone which is being crushed there carries a fair 
percentage of sulpburets, which are well worth saving by a clean 
concentration. This certainly must appear as a retrograde step in the 
face of modern practices and experience elsewhere. 
Nothwithstanding that the Queensland mills are crushing 
annually some 400,000 tons of quartz, which may be estimated to 
yield at least 2 \ per cent, mineral contents, the production of “clean” 
concentrates, not carrying more than 5 to 20 per cent, sand, falls much 
below 1,000 tons per year. 
The only really clean pyritic concentrates which the writer has 
ever seen in Queensland came from the Mount Rose and Stockman 
Junction mill, and from the River mill, at Eidsvold. Ravens wood 
has also contributed to the production of clean concentrates, which 
in all three cases were vanner-coucentrations. By ordinary hand- 
washing operations fairly clean pyrites are being obtained in Grympie. 
The pyrites are very rarely rich on this field, but, with the present 
facilities of realising on pyritic ores, it must remain a matter of 
surprise that the crude hand-washing manipulation could not he 
superseded by something better. 
€.— TAILINGS, EITHER AS SUCH OR ROUGHLY CONCENTRATED 
WITH UP TO 40 PER CENT. MINERAL. 
The greater bulk of pyritic concentrates and slimes which are 
being treated at present by the various metallurgical works of the 
colony belongs to this class, and consists either of roughly concentrated 
tailings or the slimes from the grinding pans. Every goldfield in 
Queensland contributes its share to this material, which in its mineral 
composition may vary again between a simple pyritic form and the 
more or loss complex sulphides of the base metals. 
Its assay value may vary from 0'3 to 5 oz. per ton. Tailings or 
rough concentrates from Charters Towers with 72 to 74 per cent, of 
sand are known to have assayed from 4 to 5 oz. of gold per ton. 
The writer will only mention here a special case, in which the 
material, owing to its peculiar mineral compounds, has been more 
thoroughly investigated. 
A few years ago the Mount Shamrock Company (Grayndali 
district) erected a complete barrel chlorination plant, in order to deal 
with a large heap of concentrates assaying over 4 oz. of gold per ton. 
