Show the pitts pittsburg burg silver peak at blair nevada jn in the issue of december 1907 the mining review published an illustrated article descriptive of the mine and mill of the pittsburg silver peak gold mining company V operating near blair nevada since anat time both mine and mill have been in successful operation and while the mine has fully justified the most sanguine expectations of the company the milling practice has been reduced to such an exact science and the gold recovery has been so close to the assay value of the ore that widespread wide spread attention in metal lurg surgical ical and milling circles has been at traded to the operation of this splendid plant since the publication of the article above referred to the mill and reduction f i process of the pitts burg silver peak has been more recently written up by henry hanson his description appearing in the r los angeles mining review in its issue of length connecting blair with the tonopah goldfield railroad this district is one of the oldest in the state and for the past corf forty y years has produced a considerable amount of high grade ore which was hauled by wagon to the town of silver peak where it was reduced ap pp 0 pa in v 4 L ka interior view of the pittsburg silver peak mill the hist which we reproduce as follows the mines and plant of this company are located at blair silver peak mining district esmeralda county nevada the mining company at the beginning of present operations constructed a standard guage railroad seventeen and a half miles in in small plants during recent years however the mines have lain practically idle until the advent of the railroad the building of an electric power line and the cheaper milling facilities induced the present company after the purchase of the blair blah property and the consolidation of the mo hawk alpine group to build a plant and begin op operations orations erat ions on a large scale all machinery used at the mine and milling plants also the various pumping plants are electrically driven the power is furnished by the nevada california power company mines and equipment I 1 the mines are situated about two and seven tenths miles from blair biair and have every modern convenience veni ence for cheap mining the compressor plant consists of one 8 drill two stage inger soll rand compressor electrically d driven r i v e n and one two stage 25 drill nordberg electrically tri cally operated compressor pr assor the motor driving darivin the latter machine is of the gen speed type tho the eral electric two mines are also provid ed with very complete machine and carpen carpenter ter shops for doing the necessary operating repairs also i blacksmith shop provided with drill sharpening machinery forges furnaces etc he company has am pie lYo boarding arding house and sleeping accommodations for the men the ore zone lies on a dip of about 30 degrees the ore is mined and crammed to large loading chutes from which it is drawn off into the electric trains and transported to the crushing plant at the upper terminal of the tramway the electric haul age cars have a capacity of three tons each the cars are built with rigid frames and dump into the crude storage bin by means of an automatic tipple the cars and the tipple are of our own design and make the tipple has a capacity to dump two cars at once it is automatic in so far as the throwing in of the holding dogs and un latching of the side doors and th throwing rowin I 1 the cars into dumping position is concerned these tipples are actuated by compressed air one cylinder performing all of the above movements the crushing plant consists of ones one no 6 and two no a 3 gyratory crushers the ore is crushed in two stages to pass approximately one inch ring from the secondary crushing the ore is lifted and passes through the automatic sampling machines and the TK J W 0 1 oo 00 tr f ov f mohawk all in ore pittsburg silver peak mine discard goes to the ton tramway bin where it is loaded automatically into the tr tramway aniway buckets which have a capacity of pounds the tramway W WAS built by the A leschen sons company having a length of feet with a total fall of 1600 feet the capacity at normal speed is tons per sixteen hours the ore is transported to the mill storage bin where the buckets are dumped automatically into a receiving hopper from which it is distributed on to the twenty four inch stevenson adamson conveyor running the entire length of the ton mill storage bin this conveyor is provided with an automatic traction dumper for the purpose of uniform dis tribu t ton tion after aate r a very thorough canvass of the i iss t f r field of metallurgy for a process best suited to ore conditions it was decided to use the merrill system for the secondary treatment the present mill site was selected in order to obtain a gravity plant nothing was spared in the design construction and equipment to make the mill and its auxiliary departments a model in every way steel and concrete were exclusively used in the mill construction the machine shop is located at blair and has an equipment of modern machines and tools heavy enough to do all mine mill and railway repairs the woodworking wood working department is also complete with machinery and special tools to perform any kind of work required in the store department is a full and complete line of mine mill and railway supplies and repair parts machine extras etc this department has two floors and a full basement with power powe elevator arranged to land on all levels all auxiliary buildings are conveniently arranged for the hauling of material and freight from railroad cars to the various varl oils departments and to facilitate this feature there was installed an electric surface tram which lands material from the store department and shops to any part of the mill also delivers all mine freight to the lower terminal of tramway the stamp mill is of the usual type containing ten 10 stamp batteries of 1050 stamps driven in units of twenty stamps each by five 50 horsepower bullock motors the stamps drop ninety six times per minute with a fall of six and a half to seven and a half inches the mortars are of special design hay ing massive bases with large area and held hela to place by means of eight foundation bolts the duty of the stamps while it varies somewhat with ore conditions will average four tons per stamp in twenty four hours through a 35 mesh screen the drops of the stamps were originally per minute with a six and a half inch to seven and a half inch fall this number was redu reduced ced ed to ninety six per minute the fall remaining the same the change in the number of drops reduced both the repair and the power cost while in no way reducing the tonnage crushing is done in from five to six parts of water to one of ore outside ar amalgamation is used the plates have an area of square feet per stamp and are set on a grade of eleven and a quarter inches to the foot the water supply is pumped from silver peak through feet of six inch standard pipe against foot head to a steel storage tank thirty feet by awen ty two feet deep located behind the mill at an elevation of forty feet above the bat tery floor for this service is used a heavy r 7 in platte iron works single action dire direct ct con connected necked triplex pump the tailings tailing s after passing the amalgamation plates are conveyed to the distria sump of the clarifying department in a wooden launder twelve inches wide by et elight ht inches deep set with a grade of one and one eighth inches per foot the hot bot torn of the launder is covered w with ith quarter inch flat steel plate A tipple is employed in this launder through which the tai tailings lingi in may ay be temporarily turned to waste if n necessary lRe before forte entering the distributing sump the tailings pass through a screen box fitted with half inch steel plate perforated with seven mm holes this screen removes all wooden chips and coarse rock due to breaks in battery screens the distributing sump three feet in diameters by four feet deep with a baffle board has two adjustable gates which provide an all even pulp feed to each of the two sett settling lino cones the mill ta illings are divided into two products slimes or that portion contained 2 in the combined settling and sizing cone overflow and the sands or th that I 1 t portion discharged from the bottom of the sizing co cones nes es treatment of slimes the combined overflow from the sett settling lillo r and sizing cones flows into a distributing j sump with adjustable outlet gates from this sump five U or round bottomed go galvanized I 1 iron launders distribute the pup to five clarifying or de waterIng tanks these tanks are twenty six feet in diameter W by twenty four feet two inches deep built with a wood cone bottom sloping 45 degrees each tank has an overflow I 1 launder baunder bolted bolte to the inside of the tank the thickened slimes are drawn continuously from an ou let at the bottom of the cone contain from I 1 two to three parts of water to one part of slimes and flow directly to a sludge storage I 1 tank or accumulator twenty feet in diame I 1 ter by sixteen feet deep with 45 degree wood cone bottom the clear water over t flowing the clarifying tanks is conveyed to I 1 a sump tank twenty feet in diame diameter tei by sixteen feet deep from which it is pumped direct to the battery storage tank back of the mill by a inch aldrich triplex triplet pump sufficient cyanide and lime are added to the sludge storage tank to make a solution of per cent of cyanide with a slight protective alkalinity the pulp is agitated constantly by air and is drawn kit at regular intervals directly to the two filter presses precipitation zinc dust is used for precipitation the merrill patented triangular press and process being used two distinct solutions are handled the weak solution from the sand tanks and the combined low solutions from the sands and slimes A twelve inch rubber belt conveyor mounted on suitable rollers is arranged to operate by means of floats and counter weights at a rate kopor proportionately tiona tely to the volume of solution pumped from the tank the dry zinc dust being spread uniformly along the belt is discharged into a mixing cone at a rate proportionately to the tonnage of solution to be precipitated A jet of air agitates the emulsion and a small stream of barren solution provides a constant overflow which carries the zinc emulsion down a one and one quarter inch pipe to the suction of the pump no zinc is allowed to escape directly into the tank and the precipitation takes place entirely during the passage of the solution through the pump the pump column and the press the solution enters each frame from the topside top side channel and passes through a core to the bottom of the frame any zinc left in the frame from a previous pumping is kept in thorough agitation by the incoming in stream of solution and any excess of zinc deposited in the press during one pumping will be available for further precipitation during some future pumping the efficiency of this method lies in the fact that the cloths claths are coated with a layer of powdered zinc and precipitate so that every particle of solution having to ato pass through the cloths claths necessarily gets an inti anti mate contact with the fine zinc and also in the fact that to each tank of solution fresh 14 1 zinc is added assuring good precipitation even of a solution containing copper which seldom results with zinc shavings owing to their tendency to become inert when cop 0 per coated refining y it the refining process used ai at this plant is practically identical with that in use at the homestake Home stake briefly it is as follows the precipitate is taken directly from the ithe triangular precipitating press and placed in a lead lined steel tank where it is made into a thick sludge by adding water and agitating with mechanical stirrers the free zinc is dissolved by hydrochloric and sulphuric or by sulphuric acid alone after acid treatment the sludge is deposited into a small filter press the zinc sulphate and other salts soluble in the acid solution or water are carried away to a waste tank several washes of hot water are used after the precipitate is in the press to make sure that all soluble salts are removed the press is then opened and the add acid treated product placed on a steam dryer where it is dried sufficiently to tb screen and sample after this a flux consisting of borax and ground coke is added and mixed thoroughly with the precipitate this mixture is then at a pressure of 1000 pounds to the square inch the object 00 ifs is an 71 L af milling plant of the pittsburg silver peak gold mining co being to avoid dusting the briquettes are melted in a cupel furnace during the fusion the values are thrown down in lead while the slag is run off into pots and later rerun re run in a small blast furnace together ether with cupel bottoms sweepings and other products byproducts by the of the lead is carried on in the same furnace and the lead is separated from the precious metals by blowing a light air current across the surface of the molten metal thereby oxidizing the lead which is drawn off from the front of the cupel as rapidly as it is formed the takes out very little value and is reground and used the following month as flux the bullion from the cupel furnace is then cut up and re melted in graphite pots and cast into bars for shipment the amalgam from the stamp mill after retorting is melted and cast into bars in the same manner labor employed all men employed in mill and cyanide plant work eight hours the regular operating 0 mill crew consists of three men on a shift in addition to this number there are two plate men and two repair men on th e day shift making in all thirteen men for the twenty four hour day in the cyanide plant four men are employed on each shift with no extras on the day shift making the total cyanide operating crew twelve men for the three shifts in the refinery two men are employed on day shift only their work consists of cleaning precipitation press and carrying on all work connected with the refining of mill and cyanide products in the assay office where the assaying for the mine and plant as well as some custom work is done three men are employed costs below will be found tabulated costs per ton of ore milled for six months including office administration and insurance expense but not interest and depreciation of plant these milling costs as far as known are less than one half those of other milling plants operating under conditions obtaining in nevada the following figures relative to the cost of labor power and water for the entire milling plant mill and cyanide furnish an interesting comparison with similar data published by other nevada companies on recoveries the following figures may be of interest for for the last quarter of 1908 and the first quarter of 1909 tons of ore were milled the net mint return son the bullion shipped show a total recovery of per cent of the gross value of the ore of these recoveries 66 per cent were made on the plates and the remaining 34 per cent by cyaniding cyan iding of sands and slimes the method of treating the sand in the secondary plant is practically the same as hat used at the homestake Home stake modified to suit the local condl conditions Lions A rw M 74 aco the leschen aerial tramway between mine and mill in the selection of a process suitable to the ore crushing in cyanide solution WAS was careful carefully lv considered and rejected because of the ini importance amalgamation plays in the recovery and the difficulty of maintaining amalgamation at a high efficiency when solution is passed over the plates while some of the ore contains considerable a lead and iron sulphide and the presence of them especially where the lead and iron sulphides sulp hides occur jointly are excellent |