| Show the nevada packard mill lovelock nev dec 9 the nevada packard mines companas Comp anys new cyanide process mill began operations last week it has a capacity of tons every twenty four hours there is sufficient ore on the dump and blocked out in the mine to keep the mill in operation for about two years the mill was constructed by K freitag the companas comp anys consulting engineer it is equipped with the latest improved types of machinery several new innovations are introduced trod which tend to lower the operating cost and considerably increase the general efficiency of the plant it is so constructed ted that it can be operated by six men while many mills of similar capacity require almost twice that force crammed direct to mill the ore is crammed direct from the lower tunnel of the mine to the crushing plant and dumped into two steel bins with a combined capacity of tons prom from the bins the ore is fed to a NO 5 mccully Ic Cully gyratory crusher where it is reduced to a size of about one and a quarter inch cubes then it is raised by a bucket elevator to a revolving screen with three eighths inch square openings the finer particles passing through the screen and the coarse to a set of thirty six inch diameter by sixteen inch face garfield rolls there the ore is reduced to a size which will permit it to mass through the screen the ore is then conveyed on a fourteen inch wide belt from the crushing plant to a steel mill bin from which ton circular foot diameter by five foot it is fed to a six long tube ube mill by means of a steel apron feeder the cyanide solution is here added to the ore and is further reduced by passing through the first tube dorr classifier after leaving the first tube mill the pulp as it is now called is discharged to a dorr classifier where the very fine slimed ore is removed the coarse or sands are delivered to a six foot diameter by ten foot long tub mill where it is further pulverised pulverized sed again returned to the classifier and continued in this way until every particle of ore is ground to a firmness of mesh then it is discharged from the classifier as slimes from the time the solution enters into contact with the ore at the beginning of the tube mill circuit the extraction of the values has commenced after leaving the classifier the slimes are elevated by a spiral sand pump to a dorr thickener no 1 the pulp enters this tank twenty eight feet in diameter and ten feet deep which contains five parts of solution to one part of slimed ore settling tanks in this tank it is allowed to settle the thickened pulp being discharged continuously to the top of a twenty eight foot diameter by sixteen foot deep dorr agitator the remaining solution overflows into a clarifier equipped with canvas leaves and passing through them enters the pregnant solution tank perfectly cleansed and ready for precipitation A dean triplex plunger pump transfers the solution to two merrill precipitating presses a quantity of zinc dust is introduced into the section pump and the precipitate formed by the chemical action of the zinc dust on the rich solution is deposited in the process and removed about every two weeks to be mixed with fluxes and melted into bullion bars the melting is done in a refinery in a separate building equipped with oil fired furnaces the solution discharged from the presses presa s is free from gold and silver values and is used for washing the pulp as it enters thickener no 3 returns to agitator returning to dorr agitator no 1 where the pulp entered from thickener no 1 it is agitated by compressed air and mechanical stirrers for twenty four hours and discharged continuously into dorr agitator no 2 when all pulp has undergone forty eight hours agitation the extraction of the values is completed it is now only required to separate the solution carrying the values from the slimes this is done in dorr thickeners nos 2 and 3 which are twenty eight feet in dameier and ten and twelve feet deep respectively the pulp flows continuously from agitator no 2 into thickener no 2 and thence is transferred to thickener no 3 by adia ephram pump the barren solution from the presses unites with the pulp in thickener no 3 is thoroughly mixed collects the values dissolved during agitation and overflows into thickener no 2 where the same operation takes place and then overflows to the sump tank from which it is pumped back to the stock tank for re standardizing with cyanide to be used again in the tube mills the flow through these thickeners forms a countercurrent counter current decantation the pulp moves in one direction and the solution in an opposite one oliver continuous filter on leaving thickener no 3 the pulp flows to an oliver continuous filter operated by a dry vacuum system where the remaining solution is filtered off the slime cake formed on this filter is thoroughly washed with fresh water and then discharged on a belt conveyor to the dump the slope of the mill site and the admirable general arrangement of the equipment permits the transfer of solutions and pulp to take place by gravity two solution pumps are used one for the precipitation presses and the other for pumping the sump solution to the stock tank these pumps are connected so as to be used for emergency pumps the mill is covered on the outside with anestos abe on the inside are hundreds of feet of hose and other up to date apparatus for quickly extinguishing a fire power distribution the power in the mill is distributed as follows A horsepower motor for the tube mills a 60 horsepower motor for the crushing plant a similar motor for driving the mine compressor a 30 tor for operating the filter vacuum pump and all machinery located in the lower part of the mill two 10 horsepower motors for the dorr machinery and precipitation press pump and a 5 horsepower motor for driving the tailings conveyor the mill foundations are placed on ben benches clies blasted out of solid rock the mill covers an area of square feet being feet long by sixty four feet wide with an addition for the tube mills forty by forty two feet the mill frame is con strutted ted of oregon pine insuring the max icum strength the entire frame is coy ered with one inch pine boards which are again covered with anestos roofing and sid ing the crushing plant is situated about eighty feet from the mill building and is twenty four by thirty two feet and of the same general construction the operation of the mill requires two men on each eight hour shift these men mell will handle the crushing and cyanide plants and also look after the mine air compres sor which is placed in the mill |
