Show the holderman filter fiber tamil triton for e the nning review by chas F spaulding spacia ng E M M S E A great deal has been said lately about the holderman filter tank companas comp anys experimental peri mental plant located in the rear of the commercial club building in salt lake city and wh which ich would well repay anyone to visit u up p to date the chemical side of the cyanide process esp especially in the handling of slimes is far ahead of the mechanical side of the problem in fact leaving out the question rf of filter presses which are costly to install expensive to operate and of relatively small capacity there are no successful methods of handling slimes with the exception of the holderman filter tank companas comp anys method 7 sri an which is simplicity itself and which can be operated at a very low cost the cyanide plant consists essentially of two or three tanks which may be duplicated to bring the capacity of the mill up to any desired tonnage the tanks are set up in a series geries see fig 1 so that the discharge from no 1 tank goes to no 2 tank and from no 2 tank to N no 0 3 tank these tanks are five beet feet two inches to affie biye feet nine ff inches iches by seven feet eight inches to eight feet by ten feet to twenty feet long and will have a capacity approximately of one half ton for each foot in length the top tank is fitted with an agitator the simplest kind being a shaft run lengthwise of the tank with packed stuffing boxes at each end and fitted with fan shaped paddles fastened with suitable clamps cianic i at distan distances cies of 0 a foot or eighteen inches to two feet apart and of varying lengths experience shows that a length of two feet with a width of two and a half anchen at the end gives the best results these paddles will clear the side and bottom six inches this agitator tank may be fitted with cross filters the same as the leaching tanks one cross filter between each paddle or between every two paddles this would increase the filtering surface and decrease materially the time or filtration the agitator tank is fitted with filtering surfaces on bottom sides and ends the same as nos 2 and 3 tanks the filtering tanks the bottom filter is best made with slats one and a half by two inches spaced three to four inches apart these are covered with one fourth mesh heavy wire screen and this in turn covered with heavy duck or canvas or with a couple of layers of sacking the side and end filters are best made by tacking cocoa matting to the sides and then covering this with duck or canvas the cocoa matting gives a percolating medium for the solution to reach the bottom though slats covered with wire screen would do as well the cross bilte filters rs are built up on a framework of one half or three fourth inch piping the bottom pipe being perforated or Z 4 iri tuURE NO i so the solution can escape to the space below the bottom of the filter the inside of the frame is fitted with one or two layers of cocoa matting and then a canvas covering is 19 sewn on covering both sides the solution filters through the canvas cenvas sides runs to the bottom of the frame percolating down through the cocoa matting filling and out through the bottom pipe to underneath the bottom filter the side pipe on the front end of the filter frame is made to extend several inches below the bottom frame this pipe is beveled on the end so that it will fit tightly into a hole in a wooden block or preferably into an iron floor plate which is screwed tightly to the bottom filter this gives an access to the space below the bottom filter to all solution running into the cross filter see fig 2 the cross filters are made of such a size as will give from one to two inch clearance around the sides wid and bottom of the filter this allows the charge to fill the tank evenly the method of operation is to ro run the ore and solution into the tank ton toi for ton of each and then to start agitating after the tank is filled and agitation started the gold contents begin to be dis I 1 Y ilea b 7 IV solved and go into the solution experience shows that it usually takes two to three hours for all the soluble contents to go into tho the solution then the bottom valves are opened and the charge is filtered the agitators may be kept in motion or not at the option of the millman by keeping them going it naturally helps the filtration by keeping the slimes from packing on the filtering surfaces in aae case you are cyaniding cyan iding sands it would not be practicable to keep the agitator in motion in four hours the charge if it contains 1 at least 50 per cent slimes will filter down in 50 5 0 par cent moisture the lesser percentage of slimes the greater amount of solution will filter off then enough solution is added to bring the moisture up to per cent and the charge is discharged charged ais into no 2 tank the solution added may be used in sluicing the charge from no 1 to no 2 tank in no 2 tank the charge is f filtered again experience shows that in the eight e g ht hours the charge is in this tank the solution will filter down to 20 to 25 1 per cent moisture this tank is then filled with solution to per cent moisture and the charge is discharged into no 3 tank the I 1 same as from no 1 to no 2 tanks in noa no 1 3 tank the charge is filtered for the full term of eight hours the moisture at the end of the period amounting to from 20 to 25 per cent assuming that we haver an ore carrying 10 per ton in dissolved values we will have an extraction of per cent see fig 3 agthe As the agitator tank is only filled to two thirds of the depth instead of adding solution to bring the moisture up to per cent we may add enough to bring it up to per benz in that case we would get an ail extraction of 23 2 3 per cent of the dissolved values see fig 4 you will notice that isay I say that a certain percentage of the dissolved value I 1 mean by that simply of the values that go into solution in all ores there will always remain a certain percentage of the values that will not go into solution unless you crush exceeding fine and prolong the agitation an unreasonable length of time if it is going to cost ten cents per ton for power interest on the investment etc for an additional length of time necessary to extract an additional five sump this is then used in bringing the charge in no 3 tank up to the desired moisture percentage the solution from no 3 tank is run through zinc boxes if or sufficient strength in cyanide so that the gold values will precipitate readily if not it is run directly into a sump and used in supplying the deficiency in the mill solution it is well to use two sump tanks one for nos 1 and 2 tanks and one for no 3 tank the solution FIGURE no 3 tank no 1 1000 gold per ton in solution 50 per cent to tank no 2 50 per cent to zinc boxes tank no 2 gold per ton in solution 25 per cent to tank no 3 75 percent per cent to zinc boxes tank no 3 gold per ton of solution 25 per cent left in the 75 per cent to zinc boxes per cent extraction of dissolved values solution added to brings bring moisture up to per cent cents or even ten cents per ton it would not pay the idea is to extract all possible go as far as you can but stop at the point where any additional extraction would cost more than the values saved if so desired the tanks nos 2 and 3 may be made enough larger so that you can add solution to bring it up to per cent moisture in that case assuming a 10 ore to begin on you can save all the extracted values with the exception of five or six cents per ton meaning an extraction of over 99 per cent of the dissolved values is now pumped up from the sump tanks into the stock tanks at the head of the mill where it is brought up to standard strength As soon as the agitator tank has been discharged a fresh charge is added and in this manner the charges follow one another in succession down through the tanks taking twenty four hours for a complete treatment of each charge the per them diem capacity of a duplicate set of tenton ten ton tanks arranged and operated as above will depend largely upon the fineness of the crushed ore the finer the ore is crushed the quicker will all of the FIGURE no 4 tank no 1 1000 gold in solution per ton f 60 50 per cent to no 2 tank tan k 50 per cent to zinc boxes to each 14 tons or per ton solution 25 per cent to tank no 3 75 per cent to zinc boxes boxe s me to each li 11 tons tone solution or to each 1 ton solution in tank no 3 25 per cent left in 75 per cent to zinc boxes per cent total E extraction of dissolved values solution added to bring moisture up to per cent the usual procedure is to dissolve the gold in the ore in no 1 tani tank with strong solution filter down to 50 per cent moisture running the soi solution ution that filters off through zinc boxes and into a sump then pumping this solution into no 2 tank with or without strengthening to standard strength to fo bring the charge in no 2 tank up to the desired moisture percentage then filtering no 2 tank down to 20 or 25 per cent moisture running we solution through zinc boxes and into a values go into solution in fact this process demands a very fine crushing of the ore slimes not being a detriment in fact talking an all slime ore not being crushed with cyanide solution it will take about six or eight hours to dissolve all dissolvable values and filter the moisture down to 50 per cent in the first agitator tank but if the values are dissolved before charging into no 1 tank as would happen if you were crushing with cyanide solution the capacity of the plant could be nearly doubled Foli following owing are the results of tests made b the holderman process on two lots of ore from the consolidated mercur mine no I 1 lot weight 1750 pounds no 2 lot weight 2200 pounds time of treatment eighteen hours each time of treatment in agitator no 1 tank 5 6 hours time of treatment in no 2 tank 6 hours time of treatment in no 3 9 tank k 7 hours total extraction in both lots averaged 93 per cent moisture in both lots averaged 28 per cent this could be improved upon by giving three hours in the agitator tank which is sufficient for the extraction of all the values possible also by putting in more cross filters the cros crois filters in no 2 tank are spaced eichten inches and in no 3 ta tank fourteen inches by spacing them nine to ten inches apart would decrease the moisture contents ia in each tank and give a much higher percentage of extraction the total consumption of cyanide was two tenths of a pound per ton the average consumption of cyanide at the con coil mercur mill is one half pound per ton this low consumption of the cyanide is due to two things the small percentage of moisture in the tailings and also the short time the solution is in contact with the ore and the base metals contained in the same |