Show description OF centennial EUREKA MINE gr WRITTEN FOR THE MINING REVIEW BY LEROY A PALMER As the largest shipper and the largest dividend payer of the tintic gintic district utah the centennial eureka is of more than passing interest it has been a steady producer and a profitable mine for years in the past and the large tonnage of ore blocked out and the active development work continually being carried on assure it a long life in the future before considering this mine in detail some points in the history and geology of this district will be taken up history the tintic gintic district was the fourth discovered in the state alta stockton and bingham being worked when the first location was made in december 1869 by a party of prospectors returning from western utah they located the sunbeam claim on the thirteenth of the month a date which does not appear to have carried the usual ill luck attributed to it other locations followed rapidly and the rich surface ore cloying leaching processes have been built in the district up to 1895 and as late as 1908 the tintic gintic smelter the most ambitious of the metallurgical experiments was erected most of the mills attempted amalgamation but water was scarce and the ore refractory so they met with poor success at present only one mill a concentrator is and into the district from the west this is the road now operated by the san pedro in 1891 further shipping facilities were provided by the rio grande which built in from the east some of the heaviest work and most picturesque engineering feats of the system being found on this branch geography the district lies in Z m view ot centennial eureka hoisting works was ruled hauled to salt lake city in wagons and shipped to various amel all the way fro from m san francisco francis co to swansea wale aurally the long wagon haux hau and the hia freight rates barred all but the highest grade of ores so early attempts were made at treatment in the district and as early as 1871 two mills and two smelters shelters sm elters were built in the nearby valley several mills including two em operating from 1871 to 1908 seven smelt ers have been built but these all went the way of the mills the knight smelter of which much was expected closed down after a years run in which the company ran behind many thousands of dollars the obstacle presented by the lack of railway facilities was removed in 1883 when the union pacific built down salt lake valley across the mountains to tintic valley juab and utah counties extending for a distance of seventeen miles north and south and thirteen miles east and west it is in the central portion of the tintic gintic mountains which are the farthest east of the ranges rising out of the bed of old lake bo bonneville n n e v i 11 e this range which is forty miles long is a connecting n link between the oquirrh on the north and the canyon range on the south and in the southern portion spurs jutting out toward the east almost connect it with the wasatch these mountains are not fiot especially high nor do they present the rugged and abrupt escarpments found in the wasatch water is scarce currant creek being the only stream which flows continually most of the water obtained for domestic and mine use is from springs and wells and from cherry creek eighteen miles distant quite recently three of the mines which have reached the greatest depth have struck water in abundance showing that a heavy flow is to be had by going suf deep naturally such a district has sparse vegetation and aside from sagebrush there is scarcely any but a few stunted and twisted pines geology the sedimentary rocks of the district eral bearing zones and for the most part extend in a northeasterly and southwesterly direction according to these the district has been divided into three zones the eureka mammoth Alain moth and godiva sioux in the early years mining was conducted in both the sedimentary and igneous rocks and pro av tf T Z pumping station 2250 foot level centennial eureka photo by leroy A palmer consist of quart and lime stones into these there have been various igneous intrusions tru and a considerable area has been buried under outpourings of lava after which practically the whole district was covered by surface deposits so that prospecting has been rendered difficult and uncertain the sediment aries are classed as the tintic gintic quartzite feet thick the 11 mammoth ammoth limestone feet thick the godiva limestone feet and the humbug formation feet a total thickness of the sediment aries of feet these measurements are on the western limb of a great syncline in which portion the beds have a very steep dip and are in some cases overturned but on the eastern limb the dip is much less rarely exceeding 35 degrees there are a number of faults cutting the district the greatest being the spy ajax fault near the town of mammoth ammoth Al which has a throw of about 1000 feet the igneous rocks of the district are rhyolite andesite and basalt erupted in the order named these rocks have been but little altered as they were disrupted after the period of folding which displaced the sediment aries each formation bears a fracture system the fracturing of the sediment aries occurring before the volcanic activity so that the fractures so ro produced are distinct from those in the igneous rocks which occurred later these fractures are most abundant in the min from the two was about equal but as the rich ores of the oxidized zone in the igneous rocks were worked out many of two or three years that the sulphide zone has been penetrated and so far by only two mines the centennial eureka and the G gemini emini keys keystone tone the centennial eureka this mine lies southwest of the town of eureka and toward the southern end of the eureka zone being the farthest south of the important pr producers of this chain of mines on the north it has the eureka hill 1 bullion beek beck and champion and the gem gemini ni keys keystone tone with dividends of record of over to which the centennial eureka adds on its own account so that this belt is known to have distributed in the neighborhood of eleven and one half millions in addition to some profits from early operations which have never gone on record d the centennial eureka ore consists for the most part of copper either carbonate or oxide with good gold values but some galena has been found the ore is usually found in the vicinity of an intersection sect ion of two fissures and the ore bodies have a nearly vertical dip the width varies some of the slopes being over feet wide until within the last year the main working entry of this mine has been the cen tennial eureka shaft two compartments and a manway carried vertically to a depth of 2250 feet quite recently this shaft has been tapped at a depth of feet by the holden tunnel through which the ore and supplies are transported each compartment of the shaft is four by four feet tim 0 tt n A k aw HIM 7 cribbing at the centennial eureka photo by leroy A palmer the mines were abandoned although some of them that resumed operations and sunk lower found good sulphides sulp hides at depth the sedimentary rocks have produced steadily from the first and it is only in the last bared with eight by eights and the ground is a firm limestone when the upper levels were driven some years ago they were spaced at irregular intervals apparently without any definite system in view the first level is driven feet below the surface and from it down to the 1400 the average distance between levels is feet from this point the spacing is at regular intervals of feet but as at the depth of 1400 feet the vein has dipped a considerable sid erable distance away from the shaft only every alternate level is carried through to the shaft and blind levels are driven between the levels from the shaft below the 1400 are the sixteenth eighteenth and twentieth the latter at a depth of 2250 feet below this level is a sixty five foot sump these levels run through a good lime formation so that little timbering is required they are carried five by seven feet and laid with an eighteen inch track sloping and timbering is done by the underhand method with square set timbering when the ore is reached the drift is widened out and a slice cut the entire width of the vein timbered and a slice cut off from above eight by eight sawed timbers are used the walls are firm and in general steep so that in most cases the use of lagging is not necessary and as such pressure as does occur is from the sides the sets are framed with the caps butting the ore cre breaks well and as most of the are large allowing plenty of working room one man can bring down fifteen to eighteen tons per shift the ore is wheeled to steel chutes fourteen inches square and dropped down to the next level that runs through to the shaft here it is loaded on cars and hauled by mules to the shaft where it is hoisted to the holden tunnel while as stated the lime walls are firm as a rule there is some bad ground which calls for special timbering if the pressure is not extreme a set is doubled up by framing an extra set inside or if there is heavy side pressure an angle brace is carried diagonally across the set on the hanging wall side the alternate posts are carried clear to the wall where they are framed into a stull that covers the height of two sets A strut is set perpendicular to this stull and extending to the cap between the two that are carried to the wall and in this way the pressure of that portion of the wall is transferred through the three caps to the foot wall the foot wall timbering consists of short sets to the wall As a is worked out it is filled with waste or if it is so large that the timbering shows signs of working before all of the ore is extracted that portion that is worked out is off and filled only such waste as is taken out in development work is used for this purpose and a sufficient amount being obtained in this way to fill the larger on the 1000 level and in some other portions extremely bad ground has been encountered ground so bad that doubled up sets reinforced by angle braces were crushed here the are kept open by cribbing while the ore is extracted and then filled as quickly as possible this cribbing is built up of eight by eights laid with eight inch space filled with waste between and filling between the sets they are built as closely to the walls as possible and well braced to them the timbering necessary naturally runs up the mining costs but it has been found economical to timber permanently the nature of the ground is such that if any great portion of it should start to working it would get away and serious consequences would result attempts have been made at by the top slicing method and at drawing the timbers but both have been given up as too risky surface equipment the shaft house is of corrugated iron 11 1 c A N A Hang ingwall timbering at centennial eureka photo by leroy A palmer over steel frame in the boiler room are four h p stirling water tube boilers generating steam at lbs ibs pressure they are equipped with american automatic stok ers driven by a belt from a small vertical engine and supplied with draft by a four foot buffalo forge co centrifugal blower driven by a sturtevant piston valve engine A duplex plunger pump feeds the boilers the hoisting engine is a twenty by six ty inch fraser and chalmers duplex winding one half by five inch flat ropes on twelve foot reels the head frame is sixty feet high built with two twelve by twenty four inch timbers bolted together for the uprights the uprights are braced on each side by eighteen by twenty four inch tim bers tied to them with a twelve by twenty four inch strut the sheaves are of wrought iron eight feet in diameter the cages are double decked attached to the ropes with four clamps each with four bolts and are provided with automatic safety catches which operates if a rope breaks the compressor is a two stage sullivan inch on the steam end and inch on the air end it has a capacity of 1500 cubic feet per minute pumping equipment water was encountered in the centen nial eureka on the twentieth level A drift that was being run to the south encountered a water course which is supposed to be the same as that found in the gemini as the difference in elevation above sea level of the water in the two mines is only two feet the flow of this stream is gallons a minute and as no pumping equipment was in place when it was struck a concrete bulkhead was built across the drift and bailing skips built to handle such water as worked into the sump until the pumping equipment was installed the skips are cylindrical in shape with a butterfly valve in the bottom and a pointed hood open on two sides below so that it would enter the water easily these skips were hung in place of the cages and operated between shifts and found sufficient for the purpose each has a capacity of gallons the pumping plant is of unusual interest as it is the first of its kind installed in this part of the country although the united states mining co owner of the centennial eureka has installed similar equipment in its mine in mexico the sinking pump is a num number ber nine cameron which raises the water to a gallon concrete sump on the twentieth level where there has been cut out a large pumping station sufficient for four units two of which are installed each pump is a thirteen stage centrifugal of swiss make with a capacity of gallons per minute the water is taken in through a ten inch suction pipe to the first section of the pump which consists of five stages and is discharged to the second see section consisting of eight stages from which it is discharged through the ten inch water column between the two stages of the pump is a volt h p induction motor mounted on the shaft this lift of 1700 feet is an unusual one for a centrifugal pump and is probably the highest in this country when the pumping equipment was found to be working successfully the concrete bulkhead was shot out the drift extended a crosscut driven and from this crosscut another drift run to the sump these two drifts which open into the station are fitted with four by six foot cast iron water doors which have dressed edges fitting against a cast iron frame these doors swing inward against the flow of water so that they can be tightly closed in case there is a sudden increase of the flow a contingency liable to be met with in a limestone formation the holden tunnel the holden tunnel is nine by eight feet in cross section running from the foot level to a point at the bottom of the gulch convenient to the san pedro tracks it is driven in lime all of the way so that after the loose soil of the surface is penetrated there are only twelve sets of timbers in the entire length bength of 2200 feet it is laid with 36 inch track of 45 pound steel on a grade of 40 per cent for electric haulage the ore is dumped to an ore bin at the station from which it is loaded to the cars from eight air operated gates the coal is hauled in and dumped to bins beneath the tracks from which it can be to cars on the cage and hoisted to the coal bunkers the timbers are framed in a shop at the mouth and hauled in through the tunnel which handles all of the in freight and thus cuts out a long wagon haul over a steep and winding road electric power for the haulage and pump operation is generated in a power house at the mouth of the tunnel the coal is brought in over a railroad spur and dumped to a bin from which an inclined conveyor takes it to the storage bins in the boiler room are three horsepower stirling boilers with american stokers smokers sto kers the feed water is heated in a hoppes heater by the exhaust from the pumps and injected by two epping and carpenter duplex plunger pumps electricity is generated by a kw volt 3 phase 60 cycle general electric alternating current generator mounted on the shaft of a inch ballwood Bal lwood four |