Show THE ROMANCE OF A FAMOUS GOLD MINE BY DON MAGUIRE and L 0 HOWARD let us see in what kind of a position the con mercur mines company colm pany was when it took over the constituent properties what were its possessions what were its prospects in february 1901 the properties of the con mercur included acres of mining ground a 1 ton cyanide plant the golden gate a ton cyanide plant manning hoisting works machine shop steam and electric compressor plant electric ele tramway water system offices dwellings and all necessary buildings to several reasons one of the principal being that lower grade ore could be treated at a profit and it was difficult to avoid mixing poor ore with the good in order to keep kee up its tonnage it has also been necessary for the company to treat a lower grade ore in fact the main disappointment that the company has had to contend with has been the constantly dimin diminishing ishin grade of ore it has been found impo impossible sIble again and again to maintain for one year the grade of ore which was estimated the preceding year were gradually cut up to february 1901 in addition to the base ore which was roasted and the oxidized ore which was treated raw a third class known as mixed was maintained this ore contained a little arsenic and sulphur having some characteristics of the base ore and was very talcy dalcy the finely crushed mixed ore was before treatment in february of that year superintendent janney who has since become prominent pro t as superintendent of the utah copper com banys great mils at garfield was in charge 4 1 0 ilk clr A Ps partial view of roaster boorn photo by L 0 howard jackling furnace in operation showing cooling hearth R C gemmell now general manager of the utah copper company estimated the ore in sight january 1st ast 1901 as tons having an average assay of in his report to the company he estimated that rat mining and milling would cost cos t 3 a ton and the tailings loss would he be 1 A glance at the table containing the summary of operating results shows that the estimate of cost and tailings loss has been borne out remarkably that the estimated tonnage has been exceeded but that the grade of ore has not been maintained due for the first three years of its existence the record of the new company continued to be romantic in that it was exceedingly good for the three years ending june 30 1903 the company treated nearly a million tons of ore from which over four and a quarter million dollars in bullion was obtained dividends of over a million dollars were paid and the mill was run at a capacity of about tons a day with the best extraction that the company ever suf succeeded in getting the losses in tailings were high but to counteract this expenses and made attempts to treat the oxidized and mixed ore together making tout but one class of them by making a cleaner separation between the base ore and the new mixed it was found that it was unnecessary to roast this portion of the ore the mixed ore was charged to a depth of two and one half feet and roasted base ore distributed on top A satisfactory leach was obtained a part of the roasting costs were eliminated and much of the fine crushing avoided early in 1902 the driers were donnaway done away with pus thus cutting puk another item of ex pense at this time one third of the or ore re all base came from the golden gate mine the base ore of the mercur cine although coming from the same strata carried less sulphur and arsenic and was much easier to roast the moore slime process for the six months ending may 1 the tailings averaged a ton in the attempt to overcome this loss experiments were made with the newly invented slime process evolved by george moore at the sunshine quine hinline in the same district it had not met with success on the sunshine ores but mr moore assured the directors of the company that he had now worked out a practical process the mechanical features were examined and approved by a mechanical ch anical engineer and with high hopes construction st was in may 1903 the tests led to the conclusion that fifty cent tailings could be obtained it was estimated that the plant could be installed in three months which tail fall are handicapped by mechanical faults the net result of the years operations was a loss of four cents a ton the plant was thrown out on may and no f urther further attention has been given to the process groces 3 at mercur had the moore process succeeded there would undoubtedly have been some profit from operations but pioneers must suffer in the early days of untried processes trials and tribulations the fiscal year ending in june 1904 was full of trouble the tailings averaged monthly as follows 8 83 0 cents 84 cents 89 cents 95 cents 94 cents 94 cents and an the low grade of the base ore caused the company to put four of its roasting furnaces out of commission five being retained from july to december tons were treated daily from january to may the tonnage was below during june and thereafter an attempt was made to maintain the tonnage at slimes plant installed an experimental plant had been built in july 1906 and experiments were made as I 1 to the limit of crushing solubility of values strength of solution ratio of solution to ore time of treatment desirability of agitation settling efficiencies decanting and filtering results submitted to the directors were met with an authorization for a ton slime plant which began operations in july 1907 on a small scale and was completed ed in september results were so good that no ore was treated except in this plant tonnage was too low however s so 0 the slime plant was given all it could handle and the remainder of the ore was treated in the old way the slime plant did not work well on base ores very low tailings 44 to 48 cents a ton were obtained while treating straight oxidized ore but when base ore was added to the charge the losses rose to 90 cents however in the months when the slime plant was down the tailings j fri U IF OR al the mercur filter plant showing leaves and pipe connections mercur mixer classifier dorr classifiers and thickening Thicken lne cone photo by A C selby photo by L 0 howard eight of the twenty six leaching tanks which the company then had were given over to the slime plant trouble and grief were continuous defect after defect appeared and was remedied until in june 1904 over a year later nearly had been expended on construction the company being compelled to spend money in perfecting details which moore should have perfected himself A little more experimentation by moore would have saved the company thousands of dollars but moore had jumped from a small laboratory filter to leaves that were twenty by four feet they were unwieldy the vacuum pump was mounted on the basket there was no classifier available to separate all of the sand from the slime and consequently the material packed in the vats the flat bottom tanks did not permit of using any efficient agitation stresses set up in the huge plates cracked the cake the vacuum failed and dropped the cake and in fact the equipment equi piment was worthless because of faulty mechanical construction yet inventors are prone to do this very thing today it would seem that most apparently meritorious inventions in the following year although for short intervals ilter vals tailings losses were heavy the average loss was reduced and milling bosis costs book took a big drop in 1906 an additional set of rolls was put in commission in the crushing department and the sixth furnace was wa s again brought into usey use and an average of 68 tons per furnace was roasted in the leaching department tests showed the advisability ity of using lime instead of caustic soda for neutralizing lime proved to be cheaper I 1 and the cyanide consumption dropped attempts were made at treating slime by decantation methods but settling e difficulties wit with lithe the talcy dalcy ore and lack of water limited its application lack of storage capacity at the mill coupled with mine troubles caused many interruptions to smooth operations in the year ending in june 1907 other causes contributed to a bad year coal shortage power troubles repairs to ito shaft etc were disastrous to mill results an attempt was made to leach the oxidized ore alone but slime troubles prevented satisfactory leaching ran over one dollar a ton so that the value of the slime plant became apparent even for treating base and oxide ores combined it was deemed more economical nevertheless to put the slime plant on fine oxidized ore and to leach the base and coarse oxidized as before in 1908 experiments looking to the ad j option of zinc shavings in place of zinc dust for precipitation purposes led to the de casion to retain zinc zine dust clust on may alay 8 1908 the collapse of part of the fe leaching beaching plant put eight tanks out of ofa commission so that since then but eighteen tanks have been available for leaching more tanks and filter frames were then added to the slime plant to make good the loss in capacity alie or treatment from this time on was to dry screen tile the oxidized ore into two classes fine and coarse the latter malting an ideal leaching product the fine oxidized and the roasted base were then sent to the classifiers slime going to the filter plant and the sand to the leaching tanks i progress hasl has been briefly traced from year to year but the reader is referred to the accompanying tables for further details these tables may be made the subject of close study and many interesting deductions from them are possible we content ourselves with furnishing the figures and forego comment thereon last mercur practice the last skip of ore was hoisted o ns day march 30 Q 1913 the practice to be described is that obtaining for the few months preceding g I 1 that date the method of hoisting and distributing the ore to the bins is the same as described earlier in these art articles cles the grizzlies grizzlier grizz lies used arb are ten and sixteen feet long the bars having a top width of one inch and a bottom width of seven eighths inch they are set on a 45 degree slope two no 6 gates crushers do the coarse breaking dimensions of equipment will not be repeated at this time where no change has been made since the erection of the mill the flow sheet will be sketched d briefly the reader being referred the product of the third set of rolls is elevated to a system consisting ot two 7 foot by 3 foot screens with 1 6 inch square aperture set in series the under size falls to the fine base bins the oversize from the second going to a set of small rolls set tight then to no 6 elevator crushing the oxidized ore oxidized ore from the middle bin is delivered by a 16 inch belt 28 feet long up a 6 degree incline to a 20 inch belt 98 feet long which also receives the feed from the outside bin the flow of ore here is similar to that on the base side except that one set of coarse rolls is omitted and the final sizing is done in a compound the two bertholet screens have 38 inch square apertures aper tures the has a three foot inside screen and four foot outside screen and is 8 feet long three sizes are made on vz 12 inch through vz 12 inch on 38 inch and through 38 inch the minus size goes to the fine oxidized bin along with the undersize from the Bert holets the middle 46 4 6 ij i H ze za 4 r 4 i i J 0 jh 4 ff 5 e eci c fonal on a 3 5 ide d e eleya tion 6 n kcf dele va tion A 1 I fr I 1 A 1 i 1 al A A A A A AT f S 1 r S flank f S j 1 l 3 IV x bolts C is ui 1 4 cy 13 h 3 v J REVIEW t r a za eafon 0 17 B cn 7 plan and elevation of the mercur mixer classifier to the accompanying diagram of flow for any gaps which ch may appear in the descriptive account crushing the base ore during the latter part of operations the base ore averaged about thirty five per cent of the total this ore is fed to a flat 14 inch belt conveyor by plunger feeders this belt carries it over the old drying floor to the fine crushing department and delivers to the first bertholet screen all of these screens on the base side are three feet wide and ten long set at a 45 degree slope the apertures aper tures are rectangular ular 16 1 6 inch by inch wire cloth being the material of the screens the oversize goes to the first coarse rolls set to 3 inches thence to a second screen from which the oversize goes to another set of rolls set at 11 inches thence to another screen and finally through a third set of rolls set tight the undersize from all the screens is piped to the boot of no 5 elevator which delivers to the fine base bins size drops to the coarse oxidized bin an 18 inch belt conveyor 20 feet long delivers the oversize to the fine rolls which are set tight from which the product drops to no 2 elevator and is returned to the circuit roasting the base ore ore from the base ore bin is to the boot of a bucket elevator which delivers by pipe to one of three roasting furnaces the other two being served by belt conveyor details of these roasters asters ro have been given elsewhere screw conveyors discharge the cooled calcines to bucket elevators which dellver deliver to the slime plant or discharge to the base ore pit from which the roasted ore was formerly crammed in cars and charged dry into the leaching tanks of late years yeam however all roasted ore has been delivered to the slime plant but one roaster was in commission toward the close of operations the slime plant fine oxidized ore from the fine ore bin and roasted base ore are mixed with lime solution and cyanide solution containing 18 pounds of to the ton in a mercur mixer classifier a device developed at this plant iby by the management the mercur mixer classifier the machine is an inclined trough in which is a shaft carrying steel blades rotating at 26 R P M the coarse ore is pushed along toward the upper end disintegrated and intimately mixed with and lime solutions A water spray at the upper end washes off any adhering slime the slope and the amount of water flowing oving fl down it are s uch such that only the coarsest material is carried up the blades are cast in two parts and bolted to the shaft the general dimensions and appearance of the mach machine ne are shown in the illustration aarl drawing tow of these classifiers are in series the first being set at a slope of 1212 12 degrees the second at 14 degrees one machine did not clean the coarse well enough so the second was added and given a steeper sope slope to take out more of the fine the pulp to be mixed and classified is fed part way up the trough as in the dorr class classifier coarse ore is discharged from the upper end a mixture of sand and slime can be taken off by spigot at the lower end and a slime overflow obtained classification is completed in three dorr classifiers in detail the system of class classification fi is as follows sands from the first mercur mixer go to the second those from the second to the leaching plant by launder the thick slimes and sands from the first mixer go t the first dorr classifier the thin slime from both mixers going to a 3 foot by 3 foot thickening cone which sends a thick slime with some sand to the second dorr the sands from the first two dorrs go to a third the sand from the latter joining that from the mixers and going directly to the leaching plant the slimes from the dorrs and the overflow from the cone go to the filter plant improved drive on dorr classifiers the dorr classifiers which are in use here are worthy of some description it will be remembered that one of the many reasons for the failure of the moore process althis at this plant was the lack of suitable classification fi the mercur mi mixer xer removes material too coarse for efficient work in the dorr classifiers and in combination with them gives a very satisfactory separation of sand and slime the beds of the dorr classifiers are 4 feet 6 inches by 15 feet the rakes being 13 feet ion long by 2 feet wide and carrying |