USRE12815E - Reissued june - Google Patents

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No. 12,815. v v REISSUED JUNE 16, 1908.

H. M. WILOOX. METHOD OF REGOVERING COPPER FROM ITS 0333s.

APIPLIGATIOH FILED DEG.21,1906.

2 SHEETS-SHEET 1.

mike sages: Q I Euenzaza- 144 4 Izfomey REISSUED JUNE 16, 1908.

H. M. WILOOX. METHOD OF REGOVERING COPPER PROM ITS ORES.

APPLIGATI ON FILED 13110.21, 1806.

2 SHEETS-SHEET 2.

mznessea UNITED STATES:

PliX TENT OFFICE.

HENRY M. \l'ILCOX, OF CHICAGO, ILLINOIS. ASSIGNOR TO JISMERALDA COPPER PRECIPITATING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION.

METHOD OF RECOVERING COPPER FROM IT'S ORES.

Original No. 790,238,:1atedMay 16, 1905, Serial No. 248,488.

Specification of Reissued Letters'Patnt.

Beissued me 16, 1908.

Application for reissue filed December 21. 1906.

Serial. No. 348.988.

To all whom it may concern:

Be it known that I, HENRY M. WILcox, a citizen of the United States, residing at Chicago, in the countyof Cook, State of Illinois, have invented certain new and useful Implrovements in Methods of Recovering Copper om its Ores, of which the following is herescri tion. v

e invention aims to obtain copper from its low-grade ores in metallic state by use of sulfur dloxid acting as a precipitant to throw down the copper under requisiteconditions from cupric-sulfate solution, ordinarily constituting the leach liquor, the charge being treated under roper heat and pressure in a close vessel left with certain extent of free space therein, and due attention being given by declared to be a full, clear, and exact de-v to the amount of free acid allowed to remain,

cred is apt to vary wide charges treated, although in no event is the the process thereby causing the copper to separate out practically in pure state with scarcely a trace of its oxid or sulfite present to impair the product.

Heretofore the use of sulfur dioxid as a re agent for recovery of copper from cupric: sulfate'solution has been proposed; but the conditions of treatment laid down for the prior practice fail to derive the copper practically pure, the result instead being merely to produce a large amount of copper oxid or sulfite with more or less of granular metal intermixed. The percenta e of 'metal recovl y for successive yield of much moment on comparison with the intermingled oxid' or sulfite which goes down at the same time.

Under the new treatment recovery of the 'copper is had in isolated state nearly if not wholly free from oxid or sulfite, thus for the first time rendering the use of sulfur dioxid an economic precipitant when metallic copper is the product to be obtained.

While the present invention does not depend for its success upon any special form of lant or of recipitating vessel, experience ias shown t 'at an apparatus such as lllustrated by the drawings that accompany may carbonate or'oxid ores of low grade. A

In the accompanying drawings, form ng be used to advantage in dealing with copper 1 part of this specification, in which like numbers of reference denote like I they occur, Figure 1 is a diagrammatic view of the main parts ofthc apparatus, partly in elevation, and partly in section; Fig. 2 is a vertical sectional 1 view of the precipitating tank used; and Fig. 3 is a View. of the leachmg barrels and adjacent vats,in elevation. The selected ore having been'crushed and ground, as usual, is digested in rotating barrel 1 (shown in a conventional manner) with dilute sulfuric acid of not more than ten per cent. strength until the reaction with the copper in the ore is complete and the solution becomes neutralsa at the end of several hours. Test showstiie finished solution to-be of about 1.17 specific gravity with some 6.00 per cent. of copper present therein. Any increase in the strength of the'acidwill correspondingly increase the content of copper; but the point of saturation for the cupric-sulfate solution is soon attained, when the metallic copper prescntranges, say, at about seven per cent. (7%). Regard being had to the lower reach of temperature to ensue in course of treatment later on, it is obtion only to lose a ain the excess salts when the solution cools down or chills. Hence the maximum acid strength may for economy be fairly fixed at about ten per cent. (10%), as already stated. The specific gravity of the solution varies somewhat in keeping with the quantity of refuse salts, such as iron or the like. After leaching is over the resultant from barrel 1 into the elevated settling-tank 2, while the refuse ore removed from barrel 1 is washed in tank 3 to recover the remnant of sulfate solution. Having run the dilute wash liquor into neutralizing tank 4-for reuse,

away upon the dump. The hot solution of cupric sulfate present in settling-tank 2 may be treated there by airblast tothrow down any excess of iron salts or other impurities if present in quantitysay five per cent. or over-:sufficient to prove a nuisance later on. Should the iron or other impurities be pres But only in minor quantity, theycan be ignored. After the precipitates settle away viously useless to saturate the cupric solu-.

cupric-sulfate solutionlin hot state is drawn the refuse ore is taken out of'tank 3 and cast parts wherever delivered by pipe 9 topmost absorption-vat 6.

.Cooler 5 may be a simple pipe r'ebent in serles formiand submerg in the water vessel.

Absorption-vat 6, likethe others of the set viz., 7a'nd 8is closed at top, but near the base is furnished with a perforated false bottom to sustain a charge of crushed co per ore, ordinarily'such as the'solution itself comes from. At' bottom the companion vats 6, 7, and 8 are united by suitable pi es,

through which the solution of cupric su ate .is tapped'ofi and descends from vat to vat at intervals, sa of about every two hours. The ore foun in such vat acts to take up any free acid, so that the sulfate solution is kept "neutral whileabsorption by it of the sulfurdioxiddgas proceeds. A suflicient sup ly of sulfur ioxid can be had b burning su ur or sulfid' ore in some suita le furnace, from Whichv the evolved gases are drawn by aid of' an exhaust-pump, with cooling-coil between to chillthe gases before passing through the pump". After leavin the pump the irectly into the ower' absorption-vat 8 at a point beneath the false bottom thereof. The dioxid gas bubbles up through the charge and passes on from vat to vat b pipes 10 and 11 until it is completely absor ed, the associated nitrogen finally emerging through exit 12 at vat 6 to the air.

The. cupric-sulfate solution greedily dissolves the dioxid gas passing through it, so

that the solution in lower.vat 8 after an hour or so becomes completely char ed. It needs no more and is at once drawn 0 into storage tank 14 in readiness for precipitation treatment. The absorption of the dioxid gas is attended by a marked decline in temperature, which must result in turn in fouling the vats and connecting=pipes with a deposit of cupric sulfate passlng out of solution if in exsulfur dioxid stands at about Fa renheit cess at the low degree of heat.

The solution of cupric sulfate char ed with and is found to contain: copper, 5.80 per cent;- combined sulfuric acid, 8.96 per cent.; and sulfur dioxid, 3.00 per cent., with a s e cific gravity 1.18 f for the solution. he charge passes from stor'a etank 1 4 into the precipitatin vessel 13, w ich is made in any convenient or'm, here shown as a simple upright flue-boiler withthe liquid circulating in 5.5 charge surrounds the fines: between the its flues 15, while the steam for heating the boiler-head plates 16.

' According to practice distinctive of the invention, care must be taken not. to overfill the boiler with the charge. Speaking roughly, a space representing about onetenth of the total content of vessel 13 must be left vacant.. When reaction occurs at high heat, the sulfur dioxid is energetically driven off in gaseous state. Space ample as is:

' cent.

the clear solution of cupric sulfate is allowed enough freely to receive the gas must be left to runfrom tank 2, through cooler 5, into the within the vessel, so-that,alt-ho1.1gh still held within the vessel, the sulfur. dioxid is no longer detained in the. body of liquid to impair the success of the reaction. Were the tank filled practically'full, experience shows that it is impracticable to attain the requisite degrees of heat and. pressure,

and in such cases the copper goes down largely as an oxid or sulfite. It is best to provide amplespace beforehand for free exit of the sulfur dioxid from the body of liquid at the critical reaction stage, lasting but a minute or so. I I Having filled the-boiler to the desired extent,the charge is simply heated in the closed vessel until it attains a proper temperature' e 9., about 230 Fahrenheit and upward,*although the best results-are obtained at'a temperature 'of 260 Fahrenheitat which juncture it is under about one hundred and five ounds pressure. The reaction proceeds quic ly'with marked energy, the copper sepone-third of the total cocpper present-1n solution has been obtaine showing 99.7 per' cent. pure, while the spentflliquor remains still rich in copper, analysis of the solution at specificv gravity 1.175 dlsclosing copper, 3.87 per cent; combined sulfuric acid, 6.00 per cent..; free sulfuric acid, 7.53 per cent. V Whenever the amount of free sulfuric acid in the spent solution is in excess of that required to dissolve as much copper from the tion was produced, a suitable proportion of this s ent solution may be treated separately order to neutralize such excess-of sulfuric acid, and the resulting neutralized spent solution may be evaporated to bring n the amount of on ricsulfate to the original strength, name y, six per. cent. of copper. The main 'ortion of the s ent solution may be returned to the ore-tan s in order to neu- 1 1o ore as was precipitated, when the spent solu- .with irnestone or other suitable material in a tralize its free sulfuric .acid with unleached copper in the ore, after suflicient water has.

beenadded to bring. the solution to its origi-. nal volume, so that the percent. .of contained copper when the solution. is neutralized not exceedthe stated maximum of six. per

While the ordinary ractice contemplates the use of dilutesulfuric acid for the leaching the revolving barrel 1 in liquid or gaseous' sulfate solution of copper on withdrawal while there agent, it is entirely feasibletoemploy sulfur dioxid in its place, this being introduced into form until the water (present with the crushed ore is fully saturate The sulfur dioxid attacks the-copper, iron,

etc., present in the ore and may need to be replenished by further supply as the reaction proceeds. After leaving the barrel or even a minor percentage of sulfuric acid can be added to advantage sufficient to avert any premature deposit of copper oxid that might otherwise occur once the sulfur -dio'xid in solutionsliould become deficient in quantity requisite to hold the copper in solu-' tlon.

Owing to the heat of reaction the sulfitefrom barrel 1 should be chilled down, as be-. fore, by aid of co0ler5 after leaving the set- I tling and purifying tank 2 in passage direct to store e-tank l4. Slight additions of sulfuric aci may occur at both tanks should the sulfur dioxid prove insuflicient to stop pre- IIISItHIB'dGPOSIt of the co per in oxid state. Accordi to the modifie ractice the copper solution is not required to pass through absor tion-vats 6, 7, and -8, since'the sulfur dioxi has-already been introduced at the outset as a dissolving agent.

By either practically a saturated solution of sulfur dioxid in readiness for treatment under heat and pressure at-theiprecipitating vessel 13,

havlng suitable space left therein for conagent to form point.

ering fined escape of the'sulfur dioxid,,while the copperseparates in'metallic form during the reaction. Either plan 'of leachin falls equally within the scope of ti presently set forth; 1 v The proportions-dc e claims eretofore stated are given for sakeof illustration only with familiar practice, and are not to be taken as exclusive; Variations therefrom may occur accordi'ngto the knowledgefof persons skilledin the art without essential de arture fromthe scope of thein'v'ention. laving thus described my invention, what I claim as new, and desire to securelby -Letters-Paten't, is zh 1. The herein-described processfof-rec'ove metallic copper from its s,ore's, which,

consists in leachingthe ore with suitable recuprle sulfate solution, dosing the solution after, while said solution is under a relap'erature jre '2 The herein-described process .of'recov: ering copperfrom its ores, which consists in leaching the copper from the ore with suit-: ablereagent toforin a neutral cupricosulfate solution,

suita procedure copper sulfate is found present .in solution associated with;

Y subjecting the same the fore ees of heat, percent,

in keeping ecting same to the excessof sulfu ic'a'cidlformed;

with sulfur 'dioxid, and, thereressure, heating same to a temativelyhigh above the boiling p g 5 "solution, dosing the solution-with sulfur di-.

- theboiling point.

closing the solution with sulfur dioxid, and, thereafter, heating said solution to a temperature relatively high above the boiling point under pressure suited for precipitation of the copper, in metallic form, and, subsequently, neutralizing the excess of sulfuric acid formed.

3. The herein-described process of recovering copperrfrom its ores, which consists in. leaching the copper from the ore with suitable reagent to'form a neutral cupric sulfate solution, dosing the solution withsulfur dioxid, and, thereafter, heating said solution to a temperature relatively high above the.

boiling point and under pressure suited for precipitation of copper in metallic form, using a part of the resulting spent solution With its excess of ffee acid for dissolving cop,- per from a new lot of ore until neutral for a new precipitation-0f copper in the metallic form under suitable heat and ressure after dosing with sulfur dioxid, an neutralizing the free sulfuric acid in the remainder of the spent solution with limestone or other suit-1 a le reagent, evaporating to original strength and precipitating metallic copper under I b e heat and pressure after dosing with sulfur dioxid. i

4. The herein-described process of recovering metallic copper from its ores, which consists in leaching the ore with suitable reagent to form cupric sulfate solution, dosing the solution with sulfur dioxid, and, thereafter, heating said solution to a temperature. relatively high above the boiling point and.

h to pressure. 7

5. The herein-de'scribedproces's of recovering metallic-copper from its ores, which consists in leachi agent to form on riesul'fate solution, dosing; said solution with sulfur dioxid', and, thereafter, heating the solution to a temperature relatively high above the boiling'point, sub pressure and neutralizing 6. The herein-described process 'of recovg the OIG'With suitable re tiring-metallic copper from its ores, which I consists in leaching the ore ,with suitablereagent to form ,cu ric sulfate solution, dosing said solution'wit sulfu'r dioxid, and there after heating the solution to such temperature [as ,fd-rivef' oif enough sulfur dioxid,. and generatefenough steam to subject the solution to a' pressure of pounds per-square inch. v 7;:-=The ;herein-described process ofj-recoveringco the metallic state from its approximately. 1-05 or in ores wh c hconsists in leaching the' ore'with suitable reagent.- to form cupric sulfate solution, removing the excess iron ,saltsfrom said oxid, and, thereafter, while said solution is under 'a' relat1 vel high pressure,- heating same to a relative y high temperature above V S. The herein-described process of recovcring copper, in the metallic stat-e from its ores, which consists in leaching the ore with suitable reagent to form cupric sulfate solution, blowing an air-blast through said solution, dosing said solution with sulfur dioxid, and, thereafter, While said solution isunder a'relatively high pressure, heating same to a. relatively high temperature above the boiling poin 9. The herein-described process of recovering copper from its ores, which consists in leaching the ore with suitable reagent to form cupric sulfate solution, removing the excess of iron and otherimpurities therefrom, dosing said solution with sulfur dioxid,

and, thereafter, obtaining a precipitate of metallic copper by heatingsaid solution to a relatively high temperature above the boilmg point while same is being subjected to a pressure in excess of 100 pounds per square inch.

. 10. The herein-describedprocess of recovering copper from a solution of cupric sulfate contalnlng not more than 5% .of ferrous sulfate, which consists in closing the solution with sulfur dioxid, and, thereafter, while said solutionis under a relatively highpressure, heating same to a temperature which is relatively higher than the boiling point.

11. The herein-described process of recovering copper from a solution of cupric sulfate, ,which consists in dosing the solution -With sulfur dioxid; and, thereafter, while said solutionis retained in a closed receiver having proper vacant space therein, sub ect- 'ing said solution to heat and pressure.

In testimony whereof, I have aflixed my signature 1n the presence of two w1tnesses.

HENRY M. wILooX.

Witnesses:

WILLIAM B. POTTER. HUGH KuWnounnh

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