Arizona republican., 1898-06-19
PROGRESS IN MINING.

A letter has been received in relation to the milling of gold bearing ores, in the course of which the writer asks than we are doing to know what changes to make in mill methods? J
 Few mill men seem to be doing any thing to determine what, if any, changes are required Most of. them are working by rule of thumb. Abso- lute scientific knowledge of what men are doing in milling is a very rare thing. For instance, man talks to us about shines, and we ask, What is your definition of sIimes?" Most of them answer Finely pulverized ore. y They can give no other definition. The fact is the question touches a funda- mental principle in ore milling, It re- lates to the size of crushed ore, and the value in each size. Shines may be considered as all ore that will pass through an 80 or 100-mesh sieve, or the material which does not settle in some stipulated time, when at rest, or it may be considered the difference between mill tailings and tonnage. One of the steps to be taken is to get an average of tailings, and, after sizing them, de. termine1 the values in each size. One test in this way is not conclusive; sev- eral tests should be made to determine the truth. These Investigations should extend to the pulp when it goes upon the concentration tables used as well as when it leaves them. In this way the degree of fineness of crushing to be sought can be obtained. It is one of the first steps, or A, B, c move ments in determining where the losses are, and how to reduce them, if possi- ble. Upon it depends the height of or discharge height or drop, size of screen and weight of stamp required to give the best results. But this Is only one of the many scientific-and scientific means common sense accur acy-steps to be taken when one seeks improvement.
 How many people who run stamp mills eyed do any accurate sampling or assaying to actually determine what they are saving or losing? How many know the causes of loss? Very few, we imagine. To come to practical il- lustratiOns, there are plenty of mill men who never disturb tappets, even when the shoes and dies are badly worn, and the drop increases, while, of course, the discharge becomes high CT day by day. They never stop to think that, when the size which gives the best results is known, the object should be to get the ore through the screen as soon as it is reduced to that size, and to accomplish that the screen should be where it receives the greatest splash, or in case very fine material gives the best result, the screen should be where it receives, perhaps, the least splash. Books could be written on the little things in milling which are all- important. It is attention to little things in nearly all occupations in this life which make the difference between profit and loss. Because, quarter of a century ago, some mill man stated that he had determined the best way to run a mill. is not good reason for ac- cepting his doctrine, any more than custom should cause a man to always follow the old fogy notions of his fathers Wisdom was not born with. nor did it die with, the mill men of twenty-five years ago. If we can't inn prove upon the methods grown gray with antiquity, we are long way be- hind this age.-Mining and Industrial Review. % e