Arizona republican., 1903-11-06
NOTES ON GOLD MILLING.
Some Practical Suggestions on the
 Treatment of Ore.

II Is derlrabIe in milling gold ores, whether the tailings are 10 be cyanided or not. Co have the ore crushed to r,-ffr-ru dneness. says a writer in the
 Mining and Scientific press. San Fran cisco This can only be accomplished bv usinR a constant quantity of water I'm the battery. and keeping the drop of starnps and height Of screen above the die absolutely uniform Under this set of conditions the product will be fairly
 ,riforru. As the shoe and the die
 ,rsar ths stamp becomes lighter. and
 ,.oild have reduced crushing capacity
 .vrsrt for the fact that the additional
 height Of fall results in a greater num- her of fC1t pounds. so that the crush ing capacity Of a stamp will really be fyfrresead rather than diminished, if
 tha screen be lowered to the same height above the die. This is accom-
 plisbed by the use of chuck blocks hay Ing a two-inch differential. Thus the uniformity of the product of stamping lz only apprC ximate. and not actual. The taupet. which regulates the height of drop may be shifted 10 keep the drou nearly uniform. but the difference in height Of chuck blocks still exists. This may be lessened by employing cne-haIf-inch strips beneath the chuck blocks. which may be removed as the die wears down. By the. use of two chuck blocks. having a difference of two inches In height. and providing three one-half-inch strips of iron to place beneath the blocks, the discharge may be kept entirely uniform
 Generally when dies are renewed the uartlcles Of sand are cOarser than when the die is w>rn down. This is because too little attention is given to keeping the discharge as uniform as possible The amount of water fed to the battery must also be kept con- stant.
 Fine crushing In the rock breakers greatly increases the capacity of the mill It also reduces the wear of shoes and dIes in the battery, as well as increases the life of screens
 This is not a new discovery. but weli-known fact. though c1e which is seldom put Into practice Tn the ope- ration of quartz mills.
 Wet clay and earth in ores require constant attention at the feeders to prevent ciogging. Sometimes the feed er win clog at the top while the plate below is bare. This may be avoided by careful watching.
 The loss Of quicksilver in a mill where iuside amalgamatiOn is practic- cd ls always greater than where anal Ra uatlon is done outside the mortar in the same mill. When the stamp strikes a gl0bule Of mercury fairly it divides It into microscopic spheres which are Frlashed about among the fragments Cf ore which are being constantly q hurued by the rapidly dropping rtamps. and they nave small chance of uniting with other particles while remaining in the mortar. There are vast number of these minute glObules of quicksilver in the mortar and these are dashed out through the screen to- gether with the pulp. and the greater number Of them attach tO the outside plates but many others float upon the surface cf the stream flowing over the plates and reach the vanEers where they vanish and are lost. or are carried by the belts. together with the sul- phides. tO the washing box beneath the machine. where they are washed of together with the concentrates. Here again extremely fine globules of mer- cury have a tendency to float. and these particles. together with that DOT ton Of the sulphides known as shines" may often be observed float Ing On the surface of the water in the washing boxes. This overfiows into the settling boxes beneath the vanners- 1f this overflow passes over a small wei- in the washing box. or is drawn on through a pipe. the stream falling into the settling box. a large percent age cf the floating shines and quick silver wll ascend 60 the surface of the water Of the settling tank and float a gain being eventually lost. If. how ever. the pipe from the washing box be made to dischage beneath the sur fact Of the water the shines will set tl- t3 the bottom of the box. where they may be recovered.
 Dies having an outwardly haring base are a nuisance to handle in the battery. All shoes and dies of what ever material should be uniform size. having shanks of equal dimensions, but they are not found to be cast in this way. For some reason difficult to ex- plain mill founders appear to think that having furnished a mill they will ever after be caled upon to supply the shoes and dies. and to still further en- nance their chance Of getting this. busi- ness. cast the boss heads and shoes a little different from any other. The result often is that in a single dis trict where there may be a dozen or more mills no two have exactly the ca me shaped shanks on their mill shoes, and consequently the shoes are not Interchangeable from one mill to another. There should he established a standard size for the shanks of mill shoes that all should be of uniform size regardless Of the weight of stamp. boss. stem and tappet.
 Sizing Of battery pulp before sending it Co concentrating machines produces better results than can be had by send Ing the pulp Co two machines without