Show chilean mill ill for grinding Re editor salt lake mining review my attention has been attracted by the report of J A stewart published in your issue of january 1907 regarding Z the grinding re of ores with stamps crushing to one quarter inch followed by slow speed chilean mill doing the fine grinding and amalgamation As I 1 have used this process for the past six years the following data may be of interest to mill men my mill is situated twenty five miles from ensenada En senada lower california mexico and is used for custom ores I 1 lease it to mexican miners they keeping the mill in repair it has proved a gold saver as the tailings seldom assay over forty cents per ton on ore ranging from one to seventeen ounces gold per ton my customers are well satisfied and so am 1 L in cleaning up we save 98 per cent of the amalgam obtained inside the mill and 2 per cent on the outside plates covering thirty two square feet the time required to cleanup clean up the mill is about forty five minutes an important point when doing custom work our ores contain graphite clay talc galena and other sulphur ets but they do not prevent satisfactory amalgamation I 1 use a rock breaker to crush to one quarter inch discharging into a slow speed lane mill and as no free gold has ever been found in the tailings this convinces me that the gold particles are rubbed until they are in proper condition for easy amalgamation it is a well known fact that metallic gold occurs in pyrite and other sulphide ores and that these particles are often coated with a film of sulphide of iron or other substance so thin as to be undetected the color and lustre of the gold being normal this however is often sufficient lelent to prevent amalgamation ga mation the re grinding mill removes this film by abrasion the mechanical action being the rubbing of particles against particles under a wheel pressure there are from three to tour four inches of pulp in the mill pan thus preventing steel wearing against steel which results in light expense for repairs while creating a desirable product for amalgamating concentrating or cyaniding cyan iding stamps often fail to save a satisfactory percentage of the values in ore which laboratory tests show to be free milling this is sufficient to show that something more is required than a mere crushing machine N mr stewart reports as follows the product from the stamps when examined by magnifying glass shows sharp edges and angular shapes the reground ground re product has rounded edges and globular forms I 1 have often noticed free goldin gold in the line above the sulphur etes on the wilfley tables from the stamps and none has been fo found und in those from the lane system it is evident that a series of experiments should be made in producing pulp by blows percussion grinding or abrasion for the purpose of determining which method of crushing is the best adapted for amalgamation concentration or cyaniding cyan iding in conclusion I 1 will state that in lower california where fast speed mills have been used the excessive agitation has caused slimes to often assay higher than the sands in my many tests from astras erastras ar and from the mill I 1 am now using I 1 have failed to find values in the slimes I 1 will be pleased for other parties using slow speed mills to give their experience regarding the same D GOLDBAUM GOL ensen ensenada En senada ada baja california |