US153796A - Improvement in processes for treating copper ores - Google Patents

Description

UNITED STATES PATENT :iQFEIG-E FRANCIS zwrcxn, OF "JERSEY! own-NEW JEEsEY.

IMPROVEMENT IN PROCESSESFOR'TREATINGCOPPER. OR ES- Specification forming part of Letters Patent No. 153,796,- dated August 4, 1874; application filed May 16, 1874.

, or in auxiliary manner to other processes for the extraction of gold, silver, andcopper therefrom. The invention consists of a combination of operations, viz., smelting ofthe :ores in a reverberatory furnace to a mat with admixture of sulphate of soda, forthe purpose of disintegration oxidation of the disintegrated mat in a furnace similar to a common roast-furnace suitably adapted to prevent the heat from rising above the desired degree; repetition of this oxidation after the first is finished, and the product of it has been soaked with water dissolving the sulphate of copper formed duringsaid oxidation in atank with water, and after removal of the solutiondis- 1 solving the copper still left in residue with a solution of sulphate of iron, this latter process to be repeated as long as any copper .is left in the residue, the copper in solution tobe precipitated with iron. The residue, containing peroxide of iron and all the gold and silver, being much reducedin-bulk can be treated I by any known method for the extraction of the gold and silver, or used as flux for smelting the ores, and to accumulate the bullion as far as desired. I I As the I success of this process. depends mainly upon the perfect disintegration and treatment of the ores during the oxidation or calcination processes, I will more fully describe the same, and the tests for controlling the progress of the operations.

First, the sulphureted copper ores are smelted either alone or blended with other ores in a reverberatory furnace to a-mat or regulus, and are then treated, after the removal of the dross,

. with sulphate of soda or salt-cake, say, about ten per cent. of the weight of the mass to produce the disintegration of the mass to. fine powderwithout vmechanical. grinding, in the well-known method.

Second, the powdered mat is to be calcined or better oxidized .in a furnace similar to a common roastfurnace, with this difference, however, that the floor. is not made of solid masonry, but cast-iron plates or brick tiles .restin g on flat-laid bricks, for allowing the free circulation 'of the air underjthe floor for keepin g it cool, and preventing thereby" the decomposition of the sulphate ofcopper after same is formed. -The furnace is furthermore divided by alow brick wall into two compartments,

the front part near the fire-bridge, and the .rear'partof-largersize toward the chimney. From the rear compartment preferably several fines. ought to connect with the smoke-stack,

in order to better spread the flame over the same. The matis first charged into the rear compartment,.say, in quantities of about three thousand pounds, and spread out there to lay not over four or five inches deep,.to be exposed to, amoderate flamingfire, by which it will be soon, ignited, and burnwith a faint blue flame all over the'same. Aslong as this continues the firemust be kept low, and thewhole mass be often stirred. After the blue flame has entirely disappeared the fire mustbe slightly in- ..creased, .so as to maintain afaiut cherry-red heatforabout twohours longer. After that timethe charge is drawn out, and deposited in proximity to the doors of the front compartnlent, where it will cool down sufficiently to -be mixed with water. until it, has the consist-- .ency, of stiifmasons mortar, in whichstate it is to be left. The rear compartment is, during 'the (preparationv of .this mass, charged again with disintegrated mass for oxidation. The moistened. mass becomes after'four or fivehoursoutWardIydry and hard, and has to be stirred. up with acopper spade and g the lumps mashed,'to be then charged before being completely dry. into the front compart- .ment.

Third, the mass is there exposedjfor two or. three: hours to. a dark cherry-red heat, slightly more .than the former, and racked thoroughly and often, to. be then .drawn out iclean. Shouldat any time the heat increase The following tests serve as a guide in treat-.

ing the mass in the oxidizing-chamber: If the part taken out shows after coolingolive-green spots, it is not sufiiciently long in the furnace, or not heated enough. If it shows a pale-brick color, with a gray dusty tinge, it is' in the re-' quired condition. If it should show a darkbrown color, plied was too great, and the mass is partly roasted dead, so that less copper will be precipitated, and the treatment with concentrated iron solution has to be prolonged. The oxidized matter is further treated wet, in a series of tanks, of which No. 1 may be made of iron with a fire under it, or of wood if heated by steam. Tank No. 2 is placed in front of the former and below, made of wood, with several plug holes on one side. Tank No. 3 is in front of and under No. 2, and serves, as precipitatingtank, is made of wood if steam be at hand for heating, of copper if it is to be heated by a fire below. Tank No. 4 is made of wood large and shallow, and contains the more or less concentrated solution of sulphate of soda and iron coming from preciptating tank. Tank No. 5 is made like No. 4, and contains very diluted solutions of copper, iron, and soda sulphates, obtained from washing residues,

and intended to be evaporated and to be used in the other operations instead of pure water. Tank No. 6 is also made like the former, and contains diluted solutions of sulphates of iron and copper dBP'OSited' for slow evaporation, and to be, used for washing residues containing no splphate of soda.

It is obvious that instead of tanks Nos. 4, 5, and 6 any number of smaller tanks instead of larger ones may beused'.

Fourth. The mass drawn from inner compartment is thrown hot into tank No. 2, which was filled previously with water or liquid from tank No. 5, sufficiently to cover the mass when spread and settled to about three or four times its height. After stirring well and trimming the mass more to the side opposite the plugholes, and being settled well the solution is allowed to run down into tank No. 3 through a filter hung below the plug and acidulated with a few ounces of sulphuric acid.

Fifth. The copper is here precipitated with scrap iron or iron sponge or both at full boiling heat. The residue in tank No. 2 is to be washed once or twice with pure water or with liquid from tank No. 5. Those liquids are to be used in preference to water in order to avoid unnecessary increase of their bulk. After the wash water becomes weak in copper it will be thrown back into tank No. 3, whence it'came. The precipitation being completed the remaining liquid is to be drawn hot from precipitation-tank, and poured back on residue in tank No. 2, stirred well, and

bordering on black, the heat ap duce sub-salts,

after settling let down once more into No. 3 for precipitation, after which it is poured into tank No. 4 for evaporation to recover the soda and iron salts.

Sixth. The residue which has now lost from fifty per cent to eighty per cent of the copper it contained and half of its weight is further treated with a fully concentrated boiling hot solution of sulphate of iron run down on it from tank No. l in sufficient quantity to cover i it" three or four times, and alter stirring it ;well several times during one hour, allowing it to settle, the solution is drawn into the pre- This treatment with iron socipitation-tank.

accordlution is to be repeated once or twice,

ing to richness of mass in copper until the latter is all, or nearly all, extracted. The water used to wash the residue at last after getting weak in copper is returned to tank No. 6, whence it came, the liquid, after precipitation, to be returned to tank No. 1. If circumstances admit, instead of throwing the oxidixed mass hot into tank No. 2, as de' scribed in operation fourth, it is more preferable to soak it again with water and leave it in a bin, the longer the better, stirring it up once per day, and keeping it damp. This willproand the fall of copper in first The residue,

precipitation will be greater.

which has shrunk in the treatment of rich mass to less than two-fifths in weight, contains practically nothing but peroxide of iron, and all the silver and gold which the ores contained, and either practically no copper, or as much as was left in it purposely for shortening process. If rich in bullion it will at once be delivered over to extraction by any of the known methods; if poor, it goes back to smelting as a flux for the ores which are, with rare exceptions, silicious, and are in need of iron for flux. The bullion can be accumulated with the repetitions of this proceeding to any extent desired.

The residue from pure copper ores being peroxide of iron can be easily converted into iron sponge for precipitation, which at once will recover what copper was left in it, or it may be used, as mentioned above, for flux, or both uses may be made of it simultaneously. For the treatment of mass above thirty-five percent. this method is impracticable as a self-sustaining process, but it may be made a great auxiliary to other processes.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. In combination with the process of disintegration of the copper ore by smelting with sulphate of soda, the process of oxidization of the disintegrated mass in a furnace having a floor made of cast-iron plates or thick tiles resting on flat-laid bricks, for the purpose of allowing the free circulation of the air under the floor for keeping it cool, and preventing thereby the decomposition of the sulphate of 3.- The process of treating the oxidized matter in a series of tanks, arranged and constructed' as described, for the purposes of so i lution and precipitation, substantially as and for-the purposespec-ified. V FRANCIS "ZWIGKL,

Witnessesz;

PAUL Gown, 1. B. MOSHER.