Arizona weekly citizen., 1882-08-06
Selecting Ores.

The attempt to model the working O our mines after those of England and
 France bss not at all been successful
 and in many cases met with utter fail urs. For instance, i'll the selection oi ore "vhere concentration works are not
 in use it is necessary Co sort very closely | In order to do this the ore should be
 broken to the size of stove coal. or fine
 enough to pass through tvo-inch ring. In many mines this is accumulated by
 hand. each person being provided with s large block or an old anvil, and a heavy hammer. This is exceedingly slow and laborious work, and the ore re-
 quires large amount Ot handling before | it is ready for the market. No one with
 any ideas of economy would attempt 1 hand-cobbing in a country hke thls
 where labor IS SO high (by cobblng we mean breaking all ore to small size and sorting it as it comes from the mine); 1t is well enough in England, where women do this work for fifteen to twenty cents per day, and do as much as a man at that.
 The best method of sorting is to dump the stuff as 1t is raised from the mine, after throwing out large rock that does not contain ore, into a Blake crusher set to atvo-inch gauge which discharges the broken ore into a sheet iron screen with three or more sizes of holes. The upper three feet of the cylinder may be of ons-halt inch, the middle one inch, and the lower end one and one-hRlf inches. Ore passing through this gives four grades, or three besides the fines, namely: Fines, ore one inch in dlsme- ter, orc one and one-hRlfinches in diam ter and ore two inches in diameter. The last passes out of the end of the screen. A table is arranged under each depart msnt of the screen upon winch the ore talls. This table is provided with two shoots, or openings, into which the ore is rAked by a sorter by means Of little erOwstoOt rake, as it drops from the screen. The tables may be two and al half by three feet on the top, and the ore should drop down an incline upon the back side of the table, SO as to be out of the way of the sorter, who will rake 1t forward as he sorts 1t into the shoots. which may be connected below with ore bins, or the lore may be drop ped into cars underneath the table and run out as soon ss filed. This IS very expeditions way of handling ores when close sorting is necessary, and IS espe- ciElly desirous for copper ores. ETen If good dressing works are in connection it IS often best to sort this way, more especially if the ore occurs Tn solid Jumps.
 In preparing copper oreB for the mar ket it is customary tO sort down to Iix Der cent. AS a rule, smelters will not pay much for ores that run below that percentage. Tn all cases the excessively rich ore should be kept separate. Cop per ores will always fetch mora to keep the high and low grade ores separate, since the smelters can afford, and do pay much more in proportion for high grade ores. This is also trus of nearly all kinds of ore. For instance, suppose that 1t is required to sell one hundred tons of l5 per cent copper ore and one hundred tons of per cent copper ore; shall they be mixed or sold separately? At the present rate the fifteen per cent copper ore is worth S4S.75 per ton, and the five per cent is worth Sl2.75. Sold separately they would amount to S6l.50; mixed they would assay ten per cent, l and would be worth S2s.50 per ton, and ! would amount to s57, difference ln fa- vor of selling them separately of s4.5O. l
 In sorting. not only should rich ores be kept separate from poorer ones, but the different kinds of ore which the mine may produce should be kept sepa- { rate, as zinc blende, rich sIlytr ores and . gold ores; such ores always bring more when sold by themselves than when mixed.