REVIEW OF AMERICAN CHEMICAL RESEARCH. VOL. VII.
No.
2.
ARTHURA. NOYES,Editor. REVIEWERS: Analytical Chemistry, H. P. Talbot and F. J. Moore ; Biological Chemistry, A. G. Woodman ; Carbohydrates, G. W. Rolfe ; General Chemistry, A. A. Noyes ; Geological and Mineralogical Chernistry, W. 0. Crosby and C. H. Warren; Inorganic Chemistry, Henry Fay; Metallurgical Chemistry and Assaying, H. 0. Hofman ; Organic Chemistry, J. F. Norris ; Physical Chemistry, H. M. Goodwin ; Sanitary Chemistry, E. H. Richards; Industrial Chemistry, A . H. Gill and F. H. Thorp.
METALLURGICAL CHEMISTRY. H. 0 . H O F X A N . REVIEWER.
Some Observations on Practice of Cyanide Process at Mercur, Utah. BY 1%’. MAGENAU.Miz. Sci. Press, 80, 433-464! 4gz.-The ores of the Mercur district are well suited for the cyanide process ; they run from $3.00 to $ 1 2 . 0 0 in gold, and carry some silver ; some large ore bodies contain from $1.00to $2.50 gold, but with less than $2.50 gold per ton they can, at present, not be worked at a profit. The ores are of four kinds : ( I j ‘‘ Oxidized Ore,” forming two-thirds of the ore milled, consists of ferruginous shale, siliceous limestone and decomposed porphyry. I t frequently contains cinnabar. (2) “Base Ore,” constituting onefourth of the milling ore, resembles the oxidized ore as far as the rock is concerned, but carries realgar, orpiment, and stibnite, and sometimes native antimony, further arsenopyrite. (3) Talcy Ore,’’ of minor importance, is a compact clay (decomposed porphyry) which has to be calcined before it can be leached. (4) ‘ I Black Ore,” dull black from carbonaceous matter, carrying good values, but not worked at present. T h e paper discusses only the treatment of oxidized ore, the manner of working the other ores having been described by H. I,. J. Warren (this Rev., 6, 49). A peculiarity of the work is the coarse-crushing previous to leaching, I - and 2-mesh sieves being common, the De Lamar mill only having found it necessary to use a 4-mesh screen. T h e explanation given for the coarse-crushing is that the gold occurs chiefly along minute lines of fracture into which the solutions penetrate readily. The machinery consists of gyratory crushers, rolls, and screens. T h e crushed ore, mixed with burnt lime, if necessary, is discharged into leaching tanks of 16-2 j o tons capacity. T h e common size holds 30-50 tons of ore, is circular and has sheet-iron sides and 3-inch red wood bottoms ; the De Lamar 11-23
26
Review of .47ne?ica?~ C%ei?iicaZ Research.
mill has 2 jo-tol! vats. 'I'lie filter iii coinnioii use is I: single tliickness of burlap laid on strips, nailed to tlie bottom, and protected by a second row of strips ! at right aiigles to the first) froiii the shovels, \vl-heii the tailings are beiiig tliscliarged ; tlie filtrate is somen-hat turbid, but i.0 thalJ \ V O l l 1 d be eSlE percentage of slimes i i e c1i:irg.t:. Oiil!- one str tion is used, Lcing adiiiittecl soiiietinies from a!n\ from belon.. T h e total time required for the leaching of a charge is sixty t o oiie liundred and twenty Iioiirs. I t is made iip of a number of separate percolations, the solvent being ever>- time drained off. 111 a given time, :I large number of diort percolations gives better results tliaii n fen- of long-er duration. T h e fiwt percolation lasts about eight hours. tlie others l e beeii noticed that the gold is rendered s d u l ~ l ea contact with tlie cyanide. aiid that- the bull< of tlie time is required to wxsli out tlie gold solution froiri the ore. The aniomit of ~\-asliwater used is generally equal to tlir ainount of iiiciisture reniaiiiing in the drained ore. The extraction from ore with $3.00 LO $j.oo gold per ton ranges from ;o-So pe t . , the orditiary \ - x i ations being j2-76 ;?er cent. ; n-ith ores ing oyer Sj.00 gold per toil the estractinii is normall>-a110 per cent. ; n-it11 base ores after roasting, 90 per cent. and over. Th tated from the solntioiis ( carrying T\ hen rich when poor $0.60 to 51.00 gold per t o i l ; n-ith zinc dust. T h e shavings are made of S o . 30 sheet zinc, ,iosheets at 1 2 lbs. forming a cake." Six sheets at a time are wound around a wooden nianclrel ( j inches i n diameter 1 , tied with cord self-temand then cut in a screw-cutting machine : the tool pering steel' "i is held by the automatic carriag-e and cuts the shavings from one end. X mandrel geared to 50 revolutions per niinute and cutting to i+rr inch makes j o 11)s.shavings in eight hours. T h e space taken up by the zinc in the precipitating box is I cubic foot for every 33 tons of ore in twenty-four hours. T h e precipitation with zinc-dust has already been described f f h i s A't:). , 6, 49 ) . T h e gold precipitate contains less than 6 per cent. gold. This is due to the settling out of the slimes from the turbid filtrates of the leaching tanks and to the presence of disintegrated particles of zinc. T h e precipitate is separated from the undecomposed shavings by screening with sieves ranging from 4- to IOmesh: they are then dried, sampled, and shipped to a lead smelting plant. Refining at the Forks by treatment n-ith sulphuric acid and nitric acid under a hood, provided n-ith a suction fan to carry off poisonous gases, is carried on at one mill only. The following two analyses give an idea of how greatly the percentage composition of samples of slimes varies. I '
Mef allwgica I Clzemisf r y . A1201
XU.
and
Ag’ Fea08.
Ca.
Mg.
:,$$
ZnO.
Pb.
27 AS.
Hg.
Other elements.
SO,.
I 4.j6 0.05 3.00 3.20 0.07 38.28 35.86 1 . 2 0 0.25 0.10 6.10 7.58 I1 5.26 trace 0.92 2.78 0.48 55.38 16.66 0.53 0.71 0.31 2.12 14.85
T h e subjoined analysis shows the composition of the solids of a working solution : Zn, 0.062 ; Ca, 0.005 ; Mg, o.ooog ; Fe, trace ; SO,, 0.102 ; K,FeCy,, o.oooz ; KCyS, 0.0015 ; Cy, 0 . 0 9 2 ; K , 0.1000 ; total, 0.27 per cent. There are in the district two mills (Northern Light and Chloride Point) treating silver ores with potassium cyanide. T h e ores contain 2-20 ozs. silver per ton ; the mode of operating is similar to that of the gold mills. T h e solutions contain about 100 times as much metal as those in the gold mills ; the extraction is 60-70 per cent. The Cyanide Process at Ilercur. BY D. C. JACKLIXG. ilfiilz. Sci. Press, 80, 582-609. -This paper treats of the process carried out at the Golden Gate Mill which has a capacity of about 800 tons calcined and roasted, and 2 0 0 tons ram ore. The ores are classed as oxidized ores,” a calcareous and silicious variety, “ talcy ores,” a decomposed porphyry, and ’ ’ base ores” calcareous and talcose rock with large quantities of base-metal sulphides. T h e ore is crushed to pass a 2-inch ring ; it then passes through a mechanical drying furiiace which discharges it into Berthelet screens, to separate out the fines. The coarse part goes through roughing rolls ( 3 inch apart), and after the fines produced ha\-e been taken out by sieves, to finishing rolls. T h e finished oxidized ore will pass a 3-mesh screen ( X o . 16 wire) and is ready to be leached ; the talcose ore passing a 4-mesh screen (No. I j wire) is calcined in a Jackling furnace (see this Rev. 6, 47). T h e base ore, finer than an 8-mesh screen (No. 16 wire), containing 2-5 per cent. sulphur and 1-24p:r cent. arsenic, is roasted in the same furnace, the sulphur being reduced to 0.75 per cent. and the arsenic to 0.10 per cent. T h e high percentage of sulphur is due to the formation of calcium sulphate. T h e main difficulty to be encountered is that, in the peroxidation of the iron of the pyrite and arsenopyrite by raising the temperature, the ore is liable to sinter which interferes with the subsequent leaching. I n calcining, the talcy ore is fed so as to lie 6 inches deep on the hearth, the rabbles traveling somewhat more quickly than in roasting base ores (40 ft. per m i n . ) ; the ore remains six hours in the furnace and 140 tons are put through in twenty-four hours. I n roasting base ores, the ore lies 4 inches deep, remains eight hours in the furnace, and 65 tons are worked in twenty-four hours. Careful investigation has shown that there is no volatilization - loss of gold in roasting and a very small loss by dusting. T h e oblong leaching tanks (size not given) must be large, as I tank has in the bottom eight discharge
28
Review of Ainerican Chemical Research.
gates, I j inches in diameter, through which the tailings are shoveled into trucks standing beneath. Gravel filters are used. They consist of a framework of wooden strips ( I x ;F inches, set on edge, j inches apart and held by two I Y ;F inch blocks, nailed fast 18 inches apart) 1 inches deepl filled 2 inches xx-itli inch, I inch with &-inchaud I inch xi-ith coarse sand. The three layers are separated by two pieces of I 2-o~iiiceburlap and t h e top is covered with 16-ounce burlap atid this is protected by iron strips against injury in shoveling out the tailings. T h e top 16-ounce burlap has to be renewed once a )-ear. the uiiderlying I 2-ounce burlap once in two years ; the top layer of sand has then also to be replaced, on account of its having become soinewhat clogged by slimes. In leaching, the first solution (under a head of 14 feet !, containing 0.4-0.5 per cent. potassium cyanide, is admitted from below ; it reaches the surface in about eight hours when sufficient solution is run in from the top to cox-er the charge to a depth of 2 inclies. I t is :illon-ed to stand sixteen hours, is then dranii off a i d at the same time fresh solution turned 011 : the leaching by percolation lasts :ibout 48 hours. This solution is followed by a weaker solutioii, o.-teiiiper:itui-e. T n his experience he obtained as good results a t 32‘ F. as at I -10’ I:. H e also docs iiot accept tlie state~iiel~t that tlie preci;>itation of tlie gold is at present connected with any difficulty. nntl cites a iiuniber of example.; n-it11the nec ry referei;ces to siiiistaiitinte his o ~ i experience i by that of others.
Wet Crushing and Cyaniding the Silicious Ores of the Black Hills, South Dakota,” and ‘‘ Some Further Mill Practice in Cyaniding the Silicious Ores of the Black H i l l s , South . Sci. Piass, 80, 261 : 81, Dakota.” BY J . 11. H ~ s ~ o s-71~’~. 28+ -’!he Dakota Mining and llillitig Co., of Central Cit)-, S . I>., treats the silicious ore n-est of Deadwood by n--et-stampii:,v nit11 a stock solution of potassium c)-:uiide as liattery xvater. T h e result.; haye! 011 the n-hole, been very satisfactory. The gold in the ore is present in such a fine statit of division as not to !,e readily anialgainated. It is crushed tlirougli a 6-niesh wo~-eiiscreeii, a low discharge being used. Of the pulp, 18 pel- cent. rciiiains on a 20-mesh screen, 1 2 . 6 per cent. on a ~ p m e s l i j, . 4 per cent. O T an ~ 8o-nie;h. 7.4per cent. 011 a roo-me-€1, and 49.4per cent. is fiiier than a loo-mesh screen. T h e pulp coming from the battery is rim into a wooden tank ( I G feet in diameter and 7 feet high) having an Xlderson agitator this R e v . , 6, j O j , and the overflow is collected in a sump to be pumped into the storage tank of the battery. R-heii sufficient pulp Iias collected in the tank, the battery is stopped and the agitator started enough potassium cyanide having been added to bring the solution to the most efiicient strength. Xgitation lasts about three hours, stock solution is run in and made to overflow so as to carry off the siiines which are settled in a tank large enough to liold what is formed iii a fen. days’ riin. The sands are ruii into an ordinary leaching s-at and are treated there by percolation in the usual way. T h e gold solution is precipitated by shavings in a zinc box, 13x 2 x 2 & feet, a zinc compartment being j o inches long, I S inches deep, and 15 inches \Tide. Only four compartments were found to be necessary, the rate of flow being about one ton per hour. T h e zinc boxes are cleaned up once a week. I t will benoted that there is no gold-solution tank between the settling vat and precipitation box to hold back a n y slimes that may pass along. This may make it necessary to clean up the boxes oftener than once a week. An improvement on the old arrangement is the insertion of a V ” box to settle out the sands which are then discharged into the agitating tank. T h e paper concludes with some experiments on the assay on cyanide solutions. These were evaporated in the gold pan in various ways with and without litharge, and in a lead tray. T h e ‘6
~
‘ I
Mdallu ygira I Chemistry.
3'
results show that all these methods give approximately concordant results. T h e following table will show the conditions of the solutions and the precipitation during the month of January, 1900. Columns I and I1 contain the values in dollars of the solution entering and leaving the zinc box ; column 111, the pounds of KCN per ton ; and column IV the percentage alkalinity in terms of H,SO, : I.
$3.30 2.80
11. $0.00
0.00
111.
IV.
1.1
0.3
1.7
0.55 0.5 0.45 0.7
2.80
0.40 0.30
2.80
0.15
2.70 2.70 3.00
0.0j
2 .O
0.6
trace 0.15 0.35
1.4
0.45
2.0
0.5 0.85
3.10
3.20
2.40 2.60 4. I O 3.20
3.80 3.90 4.80 4.20 4.00
3.50 4.60 4.00
0.20
0.05
0.15 1.70 0. I 5 0. I O
0.50
0.40 0.50 0.15
2.0
I .3
1.8
2.4 2.4 2.3 2.4
0.75 0.65 0.5
2.9
1.00
2. I
0.4
0.7
2.0 2.2
0.55 0.4
1.5
2.5
0.5 0.4 0.25 0.3
2.2
0.30
1.4
0.20
2. I
The Cyanide Works of the Liberty Bell Gold nining Co., Colorado. BY F. I,. BOSQUI. Eng. K n . 70, 337-338.The successful treatment of the ore of this mine is connected with many difficulties, especially as the silver is present in a form that is not readily amalgamated. Until recently the method of working (see Winslow, Trans. Am.h s t . Min. Eng., 29, 296) consisted in plate amalgamation, followed by concentration on Wilfley tables. As the extraction amounted to only 50 per cent. of the combined values of gold and silver, treatment with potassium cyanide was tried, and this proved so satisfactory that a 240-ton cyanide plant was erected. The only difficulty encountered was the slimy character of the tailings, which made filtering difficult. T h e leaching room, 190by 44 feet, has a double tier of leaching vats, five to a tier, each 33 feet inside diameter and 8 feet deep, holding 275 tons tailings. T h e precipitating room, 135 by 30 feet, holds two storage tanks (20 feet in diameter and 15 feet deep), four zinc precipitation boxes, two vacuum cylinders connected with a 7 x I O Stilwell-Bierce and Smith-Vaile vacuum pump, two Gould rotary pumps for raising solution, and a cleanup plant consisting of a 2 x 7 feet redwood acid tank, a double
I.,,
32
Review of American Chemical Research.
plunger Johnson pump, and a I 2-compartment Johnson filterpress with two sump tanks, each I j+ feet in diameter and 6 feet deep. The tailings from the Wilfley tables are run from a common center in radiating launders to the upper or collecting vats (on grades ranging from 2 . 2 to 4 per cent.), being fed by revolving pipe-distributors. The slimes are carried off by means of overflow-gates, of which there are four to a vat. By this arrangement a charge is obtained of which about 4 j per cent. will pass a Ioo-mesh screen and can be satisfactorily leached, while the slimy overflow, about 2 j per cent. of the whole, is so fine that less than I per cent. will remain on a rjo-mesh screen. From the upper or collecting tanks the pulp is shoveled through bottom-discharge doors into the leaching tanks below ( j men discharging a tank in ten hours at a cost of 6 cents per ton). From the lower tanks the tailings, after treatment, are reinox-ed by sluicing. They assay 0.07-0. I O oz. gold and 2 - 2 . 5 ozs. silver per ton. The cost of treatment for three months is shown in the following table. The item of chemicals includes cyanide. lime, sulphuric acid, and zinc :
........................
May.
Labor $0.318 Chemicals .................... 0.973 Assaying ..................... 0.014 Shipping bullion.. ............ 0.009 Taxes! insurance, and deprecia0.2 I2 tion ........................ Miscellaneous ................ 0.018 Totals..
....................
$1.574
July. $0.~jj
0.371 0.013 0.001
0.135 0.008
$o.S13
When the plant is worked to its full capacity the cost will be reduced to $0. j j per ton.
The Treatment of Low ,Grade Silicious Ore of the Rossland Camp, by Cyanide of Potassium. BY G. I-,HOPKISS. Can. Mi%.Rev., 19, 131--134.-The process used at this mill is that of Pelatan-Clerici which aims to combine lixiviation with anialgamation assisted by electricity. While it has been a failure whereever else it has been tried, it is stated to have been successful here. From a solution worth $4.00 gold per ton, the values are said to h a r e been reduced in six hours to $0.07, the current being of 70-80 amperes at 5-7 volts. T h e paper gives full drawings of the plant and interesting details as to the method of working. Telluride Ores and the Treatment of Them. BY T.A. RICKEng. Mzn. ]., 7 0 , g3-g4.--Considerable difficulty has been encountered in treating the telluride unoxidized gold ores of the Great Boulder Main Reef, Kalgoorie, Western Australia. They have been overcome by Sketves and Marriner by grinding the ARD.
A nnlytica I Chemistry.
33
roasted ores in pans, previous to leaching with potassium cyanide, and allowing the tailings to run over amalgamated copper plates to save the coarse gold. I n roasting tellurides, the tellurous oxide formed combines readily with ferric oxide, forming tellurite of iron which is liable to coat the particles of gold and make them non-amalgamable. T h e extraction is 96 per cent. on ores and 93-98 per cent. on tailings, and the cost of treatment $4.75 a ton.
The Real Fuel Ratio. BY S. C. JEWETT. Foundry, 16, 208zog.-The author calls attention to the wrong custom of judging the work of a cupola solely by the amount of fuel that is consumed. H e shows, e. g . , how different the temperature of the metal must be when a few heavy castings are to be poured from large ladles from that when small castings are made from small ladles. I n the former case the metal neednot be so hot as in the latter and the cupola will require less fuel. ANALYTICAL CHEnISTRY. ULTIMATE ANALYSIS. H. P. TALBOT,IREVIEWER.
The Relative Values of the Mitscherlich and Hydrofluoric Acid nethods for the Determination of Ferrous Iron. BY W. F. HILLEBRAND AKD H. N. STOKES.J . Am. Chem. SOC., 22, 625-630.-1n the presence of sulphides the Mitscherlich method yields high results as a consequence of the oxidation of these compounds at the expense of the sulphuric acid used for decomposition, or at the expense of ferric compounds present. T h e error from this source seems to be negligible under the conditions of the hydrofluoric acid procedure, unless the proportion of pyrite in the mineral is very large. Estimation of Pyrrhotite in Pyrite Ores. BY F. B. CARPEN1.Am. Chem. sac., 22, 634--637.-Deterrninations are made of total sulphur and of silicon by the usual methods. A portion of the ore is treated with concentrated hydrochloric acid, water, and alcohol, then dried at 100' , and weighed. This weight, less that of the silica, is assumed to represent FeS,. After deducting the sulphur corresponding to this FeS, from the total sulphur, the pyrrhotite (Fe,S,) corresponding to the residual sulphur is calculated. On the Determination of Phosphoric Acid as Phosphornolybdic Anhydride. BY H. SHERMAN AND HENRY ST.JOHN HPDE. J . A m . Chem. Soc. , 22, 652-658.-A neutral solution of ammoTER.
