| Show chief consolidated Consolidate ds new milling plant and the process it will employ from the eureka reporter sept 5 As operations in the wet concentrator of the new milling in plant of the chief consolidated mining company have started and as the remainder of the plant will soon be placed in operation it is i appropriate althis at this time to review tile the events that led to the construction of the mill also describe its construction operation and some of the results it is expected to achieve NA walter fitch president of the chief consolidated mining company and cecil fitch general manager early recognized the desirability of devising a method for the local treatment ol of tintic gintic ores they also recognized the fact that to devise a local treatment for this complex oxidized ore would require a careful study of existing processes or even the necessary research to develop a special milling method for chief consolidated ore accordingly in august 1916 george H wigton organized a special metallurgical research department for the company while the following year after some laboratory bior work an experimental mill was equipped in which it was possible to conduct experiments in a manner which would permit duplication in a commercial size mill and at a subsequent time samuel M seddon joined the department volatilization a feature after several attempts to work vork out a treatment method by standardized processes a method of volatilizing the metals from the ore was devised this process consists in subjecting the properly prepared ore to a temperature of about 2400 degrees fahrenheit heit and agitating the mass to expose it to the heating gases under these conditions the valuable metals vaporize and pass off with the furnace gas leaving most of the worthless gangue in the residue and by cooling the furnace gases the valuable metals revert to the solid state and can be separated from the furnace gases by filtration through woolen bags as and recovered in the form of fume i the novelty of this process lies in the fact that no reagents such as salt are added to induce volatilization this has resulted in the production of a non corrosive fume easily ily recoverable erable by bag filtration whose chemical compesi on ion permits direct reduction to bullion in the blast furnaces it ia is not sufficient however to merely heat any ore in order der to volatilize its valuable metals it is necessary to first arst remove constituents which tend to promote fusion of the he ore if the ore fuses before volatilization is complete comple te urther further extraction will be stopped many of the constituents its in the furnace feed can be removed by standard jandard tan dard concentration conc cent ration methods such as notation flotation and gravy I 1 ity concentration cent ration and a good grade of concentrate produced 1 it u the same time leaving a furnace feed with a high melting the chief consolidated milling process consists of a IYO rl concentration cent ration method to reco recover the metallic sulphides sulp hides and nd other fusible volatilization constituents followed by a process to recover the oxidized metals bol the new ew milling plant is situated one third of a mile ast ol of the chief consolidated shaft no 1 at the foot of ir ardner canyon the entire plant was designed and conw ed by the e chief consolidated organization and it is M 1 I sa abst anti ti ally built of steel and concrete ore will be ca carried aried U m the mines to the mill by the denver rio grande if y A description of each department follows A feature ealure of all departments is the advanced type of elect lect acal equipment and the installation of individual r tive mechanical drives wherever possible crushing and sampling plant this plant is designed to crush theore the ore to a size which will pass through a screen with three quarter inch square openings and to automatically weigh and sample the ore the ore from the receiving hopper is fed automatically to a gyratory crusher 13 inches by 45 inches which delivers a 2 inch product an inclined belt delivers the crusher product to the 60 inch by 24 inch crushing rolls which reduces the ore to three quarters of an inch the ore esthen is then weighed in transit on a belt conveyor and is finally delivered to the 1200 ton storage bin by a system of belt conveyors A continuously moving distributor above this bin insures uniform mixing and bedding of the crushed ore the discharge from the 60 inch rolls is automatically sampled by a pivoted bucket sampler of special design the sample is re crushed in 36 inch rolls the discharge of which is again sampled by a similar sampling device other equipment in the sample room includes the usual laboratory equipment for preparing the sample for assaying operation has shown that the crusher plant has a capacity of 75 tons per hour and therefore it will be required to operate only a few hours a day to supply the rest of the plant with crushed ore wet concentration plant the function of the wet concentration plant is to remove all sulphides sulp hides from the ore and as much of the oxidized minerals as it is feasible to remove by table concentration methods the concentrate from this plant is greatly enriched in valuable minerals and the tailing contains the remaining oxidized metals and its fusion temperature is is increased by the removal of the concentrate crushed ore from the 1200 ton storage bin is automatically mati cally weighed and fed into an 8 foot by 48 inch har dinge ding e wet grinding ball mill which discharges into a 6 foot dorr classifier the classifier regulates the size of the grinding by returning oversize material to the ball mill for re grinding the ground ore pulp 80 mesh then passes to pneumatic flotation cells where all sulphide minerals are removed the tailing from the flotation passes to six wilfley tables for the removal of some of the oxidized minerals concentrate from flotation and tables passes to a dorr thickener to remove most of the water and is then filtered in a 6 foot american filter the product from the filters is loaded into railroad d cars for shipment to the smelters shelters sm elters tailing from this plant is pumped to the volatilization plant for further treatment the present capacity of the wet concentration plant is a abour ou tons per 24 hours which has somewhat exceeded expectations it has proved to be very efficient for the recovery of sulphide minerals and is operating at the present time on sul sulphide bhide ore and the tailing is temporarily being sent to waste pending the completion of the volatilization plant ph nt volatilization plant the tailings from the wet concentration plant must be dried before feeding it to the volatilization furnace drying will be accomplished by filtering the thickened tailings in in two 12 feet by 12 feet portland filters and drying the filter cake in in a n 7 foot by 60 foot ruggles coles dryer indirectly fired by the hot exit gases from the volatilization furnace the dried product then passes to the furnace feed bin for storage the volatilization furnace consists of a rotary kun kiln 10 feet in diameter by 80 feet long fired at the same end at which the ore is fed the kiln is lined with 9 inches of firebrick and will revolve dt at a speed of one to two revolutions per minute the kiln is fired by a jet of pulverized coal blown in at the feed end A plant for making this pulverized coal has been built and will be described later the operation of the rotary kiln will effect the final and most difficult part of the separation the valuable metals will pass off as fume with the furnace gas to be recovered later in the bag house the residual gangue will be partially in the kiln then cooled and conveyed to the waste dump situated just below the plant bag house the furnace gases will be cooled by drawing them through a series of steel cooling pipes having a total cooling surface of square feet two large fans will then force the gases through woolen bags each 18 inches in diameter by 30 feet long 6 these bags will retain the fume and allow the furnace gases to pass through the bag house is divided into five sections of 60 bags each the fume will be periodically removed from the bags in each section by an automatic shaking device the collected fume will be removed from the bag house by a system of spiral conveyors A small amount of water will be added to prevent shipping losses and the fume will then be sent to the smelter for reduction to metal coal pulverizing plant the coal pulverizing plant is situated just west of the volatilization plant and will have a capacity of five tons of pulverized coal per hour so it will be necessary to operate this plant only about one shift per day the slack coal will be received in a steel track hopper and by means of elevators and spiral conveyors will be sent either to an open storage pile or to the dryer feed bin the same equipment will reclaim coal from the open storage and deliver it to the bin inside equipment in the plant consists of a ruggles coles dryer 5 feet diameter by 30 fet long to reduce the moisture in the coal to 1 per cent the dryer discharge will be elevated to the ball mill feed bin grinding will be done in a 6 foot by 36 inch hardinge dry grinding ball mill operating in closed circuit with a 10 foot gayco air separator the air separator will deliver a finished product 95 per cent of which will pass a mesh screen the finished product will be stored and drawn from storage to be blown into the rotary kiln the objects sought the successful operation of the chief consolidated mill is expected to accomplish 1 the elimination of barren silica from both lead and dry ores thereby avoiding the high penalty now charged by the lead smelters shelters sm elters for silica 2 A reduction in freight and treatment charges on account of the shipment of a reduced tonnage of enriched product to the smelters shelters sm elters 3 the saving of the lead in dry ores now being shipped under contracts which do not pay for lead it is also expected that the mining of low L rade ores to be sent tc the mill will aid in the development of more profitable ore in the mines |
