Show CHANGE IN MILL DESIGN the miner of wallace idaho states that the last issue of the bunker bullion a publication issued by the employed emp loyes of the bunker I hill 1111 sullivan company contains contain a contribution from R S handy superintendent of bunker hill mills in which 1 ich lie he summarized the changes made in the sweeney mill to adapt it especially to the treatment of the large tailings dump and also to handle the ore produced by last chance and other leasers leaders lea sers mr handy says in part testing tailings the sweeney mill was turned over to the bunker hill company by the federal mining and smelting smelling Sm elting company on july 9 1918 the work of sampling and eftim estimating t the contents of the tailings dump was started immediately and about 1000 tons of the tailings placed in the mill bins fr f r a working test in order to determine the of profitable alling of material the fine jigs which had been handling c material below three millimeter in size were taken out of the main mill bull building dirig their feed was sent to two 20 mesh the oversize from these passed to the coarse jigs the undersize was spouted to the old slime house where it was classified and treated on tables and van ners the 1000 ton test indicated that the milling of the tailings was commercially practicable so then the plant was belled for the convenient handling of the tailings as well as ore from leasers leaders lea sers operations in the old last chance mine workings two valuable products the remodelled remodel led mill handles about tons of tailings from the old dump every sixteen hours or it can handle tons of leasers leaders lea sers ore in the same period the old dump tailings assay about 1 per cent lead while operating the mill on this talling tailing two valuable mill products are made first a middling which is taken off the jigs and tables this middling assays essays 10 per cent lead 4 ounces silver and carries more than 20 per cent excess of iron over silica and for this reason is especially desired by the smelter for use in fluxing flexing flu xing the second product is the flotation concentrate which assays essays about 25 per cent lealand lea lead dand and 18 ounces of silver per ton A great deal deal of difficulty has been encountered in getting railroad transportation of the dump tailings and leasers leaders lea sers ore to the mill but the mill itself is performing very satisfactorily the flotation as was expected presents a problem because of the high content of flocculent oxidized matter in the feed and will require study that we may improve its working as time goes on and we experience more of its peculiarities in the working of this particular type of feed |