US1276130A - Process of treating foul solutions. - Google Patents

Description

Patented Aug. 20,1918` Punt. oLuTlou *To TANK, Houst.

CELL Il` SoLuTIoN ULPHATL) I F. T. SMITH.` PROCESS OF THEATING FOUL SOLUTIONS.

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INVENTUV l (M504 I QMPuR'ITIE-a) N 'l AWV UniTED STATES OFFICE.

raam: r. satira, or mineros-'13min 4ne'simcimsn'rrs.

, Pnocnss or 'mancino roUL SOLUTIONS. i

' Application led April 2,

To all 'wh-0m may concern:

Be 1t known that I,F,RAN1{ T. Stura, a

1 citizen` offthe Unitedv States, residing at AJamaica Plain, in thev count-'y of SuHolk and State of-Mas'sa`cl1usetts, have invented new and useful" Iiiiproyements' in the Processes of Treating Foul Solutions, of which the following isaspecication.

ThisinVentiOn relates to the treatment of impure solutions of acid and salt, such as the'foul solutions of sulfuric acid and copper sulfate arisin incoppenreneries and in thefwinningo nietalsbyl-leaching; The object of the process is the production of pure solutions o acid and, usually, salt', utilizingi the acid and salt of the foul solution. W'hen.' this process is applied 'to' foul electrolyteV from copper refineries it 'has the additional advantage of' simultaneously yielding vpure copper, concentrating most of the impurities in a 'sludge which may be used asa basic 'iu'xi lldleflllng 10W grade metal '(blacl;

copper or speise) when available;

@This process will be described by explaining its application to foul, copper-reiinery` electrolyte, for which it is especially suited.

It consists vof the hereinafter described steps whichmay bemodliied somewhat in special cass. AInstead of a relinery electrolyte, the

cleaning iron with sulfuric acid maybe used. 4In the application: Voli/the vprocess ltocopper refinery electrolytethe steps above refer-.red to-are aslfollows: 11. The concentration ofcopper in the foul solution is 'reduced by dilution,"by plating out copper using low-.grade anodes, or, pref erably, bytreating in the secondstep as' will be ex lamedlater.

2. he'foul `solution is thensubjected to electrolysis as follows: 'It ispassed through' anode chambers of electrolytic cells Vcontaining soluble anodes,while a pure solution of copper sul fate (preferably acidified'withisuh 'f "rlc acid) fiows throughthe cathode chambers; 4vThe anode and cathode chambersare separated by diaphragms in' vorder to `prevent the solutions roni mixing, yet allowlng the l anodes,

through the diaphragmv to the pure solution, f

current of electricity )to f pass through".Y current of electricity el'itersthecells t rough passes from` v the 'foul solution,

and'deposits `metallic copper'on the cathodes. Theieonduction of the current throughthe diaphragme necessitates fthe passing-'f ci'hycoppe'rfan'd otherimitals,l in the form y acid solution. o ffcrrous sulfate obtained in,

The danger of contaminating the pure cop-- V, spannen@discernment. Patented Aug, 20,1915:

m15. serial N'o; 13,746.

of ions, ,from the anolyte to the catliolyte. The negative ions more through the diuphrain'in the opposite direction, but they may e disregarded. The acid is, relatively, highly dissociated, and the hydro' en move about five times as fast as tie other ions, consequently, they will movethrough the diaphragm at the greatest rate.

These hydrogen ions re lace copper ions deposited on the cathode rom the copper sulfate in the catholyte, thereby forming hydrogen sul fate, or sulfuric acid. The hydro en ions which lpass through the diaphragm rom the anolyte are replaced bycopper lons 'formed by the'dissolving of the anode, thereb' formv ing copper sulfate. When nearly all of the hydrogen ions, (formed by the dissocia xon ofv the' acid originally present in the Loul solution) havemigratedout of the auoiyte,"'"

the' anolyte is nearly'` neutral and is their treated with a precipita-nt for iron ashereinafter described. It is to be noted that no acid will be formed at the anodes, since these will be soluble.

e More copper sul-fate is added to the pure .solution if it is 'to be used as electrolyte in the refinery tanks. Usually it will. be advisable to replenish this .solution 'with copper sulfate before it becomes too dilute, :unless it is to be used for some-purpose for which a low concentration.. of copper is desirable'. The foul solutln Abecomes richer 1n the' metals of the anode, most-ly copper.' ,The re.; duction of the gioncentration Vof copperv in this solution is made before electrolysis, since it 4was found on experimenting 'that unless m reduced, the anode becomes coated with cop er 'sulfate 'crystals before the acidit' 1sV owerelfV suiciently. The -efzzrflution is ept warm` to allow a higher concentration of copperI sulfate, as well as to save power,V

It' is obvious that as the ccnceutrationof the acid inthe a-nolyte diminishes, the other ions take a more prominent part in conduction, and the amount -of copper, nickel, and iron passing through the diaphragm with the hydrogen will be considerable if the concentration of acid iste be reduced quite low.

per` sulfate solution can lbe eliminated, and the concentration o f copper in the foul so-` lution canbereduced by carrying Aon then purification electrolysis in two stages." First,

j the foul" solution (which has not been subjected to any special treatment) is usedv as catholyta' and Vfoul solution which has lost most of its acidity is used as analyte. The anolyte loses the remaining acid, sind copper,

nickel 4and iron to the catholyte. The rate chambers of the first series of cells', to the anode ,chambers of thesecond series, in which it loses most of its acidity. series, pure copper sulfate solution is used as the catholyte. Thus,'all of the acidity lost by the foul solution'ils 'gained ultimately by the ure'copper sulfate solution.

j 3. ien the acidity of the foul solution has been reduced sufficiently, it is passed to precipitation tanks where it maybe treated with oxidsif still slightly acid, and with ferrous sulfate if there is insuiicient iron pres ent for the subsequent operations. Air is then blown through the solution to oxidz"e the ferrous iron (thereby using up any unneutralized, acid) and to precipitate-basic ferrie salts. If the amount of iron remaining in solution is too high, it is completely precipitated with a basic, commercial pre 4 -cipitant for ir'on, such as powdered limestone, avoiding an excess so that no copper will be precipitated. The solutionis kept hot to facilitate hydrolysis and to keep the copper sulfate in solution. The precipitates from these operations consist chiefiy oihcalciuin sulfate, ferrie liydroxid basic salts of' iron, antiinony and bismuth, arsenates vand arsenites. They are removed from the so-l lution by filtration or decantation, and may be briqueted or sintered ywith'fine ore or fine dust, since they contain useful basic letts. This would leave the cob-alt ;.(and, a small amount of nickel and ammonium) in solution, but these would not interfere with its use as electrolyte.

' If this process is used, the-precipitation of the iron may be accomplished by means of ammonia: thereby forming ammonium sulfate.' Nickelammonium sulfate israther soluble in hot water, so that-the'iron, arsenic, etc., can be removed without this doublesalt...A

In this,

if the; solution is kept hot. Or copper sulfate 'and nickel sulfate may be separated by crystallization, the copper sulfate being used to obtain the'required solution of copper sulfate. l

This process was specially devised for Ythe treatment of foul solutions of copper sul' fate and sulfuric yacid produced in the elec- 'The anodes may be very impure; black copper or even Speise may be used. In this case, more-copper sulfate will be consumed than is produced vin the process, Ibut thissalt is v quite cheap. The treatment of the'anode may be the main object. -In anyrcase the hydrogen ions migrate through a diaphra leaving the lslightly dissociated impurities, and replace the metal in the salt at the cathode. The hydrogen of the acid in the foul solution is replacedby metal ions from the anode, the solution becoming nearly neutral enough to allow the economical precipitation ofv certain impurities. l

The invention will now be more fully described, when taken in connection with the accompanying drawings, and the novel features 'thereof will be pointed out and clearly 95 defined in the claims at the close ofthis specification.

The invention hereindcscribed, however, "does not consist of the apparatus itself and therefore the drawings are diagrammatic,

In the drawings, Figurel is-a diagram showing the fiow` of solution under treatment when two cells are employed. Fig. 2 is a diagram representing the essential features of the cell. Fig. 3 is a diagram showing the act-ionin the cell. I f

Referring to the diagram shown in Fig. 1, i

the fouljsolution goes through the following steps. l. It 'flows from the tank house into vthe cathode chamber C1, cell I, where it is nearly freed from copper. i 2. From C1Xto'A2,cell II, where'it loses by migration to the cathode chamber C2' 115 most of the hydrogen ions, and'gains copper by the dissolvino of the anode. i

3. From A2 tofA?, cell-I, where it loses most of the remaining hydrogen ions', and gainsstill more copper.

4. To a tank in'which the iron is oxidized and precipitated,`together with thearsenidv antimony, and bismuth.

5. Through a filter, or other device to separate the lprecipitate,'to a tank for treatment 1425 -Jlonou thecathoddand 'gains acid by mil 180 gration of hydrogenions through the diaphragm Where M is a diva-lent metal (copper, nickel or the like). The hydrogen ions pass l through the diaphragm to the catholyte where the change may be represented by the equation:

,Which/replace the hydrogen ions lost by m'igration. In other wordstcopper deposits on g the ,'cathode; copper dissolves from the trolytes composed of solutions of acidand' anode; H* (to a les/s'v extent other ions) migr 'te asfshown by the. arrows.

hat I.4 claim 1s:

1, The,4 process oftreating impure elec- Vtnolytes composed of solutions ot acid and salts, said 4e rocess consisting of electro l zing v-the impure solution in the anode c amber of an electrolytic cell which containsa 4soluble anode While a solution of pure "copper sulfate flows through the cathode chamber.

`2.- The process of treating impure elecsalts, said process consisting of passing the impure solution through the anode cham-- bei' `of an electrol. tic cell Which contains a soluble anodewhi elan acidied solution of pure copper sulfate flows through the cath- 4ode chamber, the two chambers being separated from each other by a diaphragm.

3. The process of treating impure electrolytes-composed of solutions of acid and salts, said process consisting of passing the impuresolutions through the anode chamber of an -e'lectrolytic cell which contains a soluble anode while an 'ecidified solution of lpum copper sulfate fiows through the cathode chamber, the two chambers being separated from each other by a diaphragm, then treating the anolyte with a precipitent and their removing the precipitates from the solution.A

4. The process of treating impure electrolytes composed of solutions of acid and salts, said process consisting of e ectrolyzing the impure solution in the anode chamber of an electrolytic cell which contains a soluble anode while a solution of pure copper sulfate Hows through the cathode` chamber, then adding an oxidizing agent and a basic precipitant for iron, then separating the precipitate and treating the solution to leave only pure copper sulfate, then passing the copper sulfate to the cathode chamber of the cell, then passing thesolution to a tank house. Y

5. The process of treating impure solutions of electrolyte,` said process consisting of passing the impure solution `into the cathode chamber of an elcctrolytic cell which is divided into 'an anode and a cathode chamber by a diaphragm, the anode` chamber containing a soluble anode, then passing the solution from the cathode chamber of said cell to the anode chamber of a second cell of similar construction to said first cell, and containing a` solubleanode, then causin the solution to pass to the anode chamber o l the rst cell, then causing the solution to pass from the anode chamber of the first cell to a therefrom all except the pure coppei` suliate, then passing the copper sulfate to the. cathode chamber of the second cell.

6. The process of treating impure solut-ank, then treating the solution to remove tions of electrolyte, said process consisting of passing the impure solution into the cathode chamber of an electrolytic cell which also contains an vanode chamber having a soluble anode, thev anode and cathode chambers being separated fromeach other by a diaphragm, passing the solution from the cathode chamber of said cell to the anode chamber of a second cell of similar construction to said first cell and containing a solu# ble anode, then causing the portion of the so'- lution which remains in the anode chamber of the second cell to pass to the anode charm` ber of the first cell, then passing the solui tion which remains in the anode chamber of the first cell to a tank, and there adding an oxidizing agent and a basic precipitant for iron, then separating the Aprecipitate and Atreating the solution Ato leave only pure copper sulfate, then passing the copper sulfate ,to thecathode chamber of the second FRANK T. SMITH.

lVitncsses: V

CHARLES J. MAn'rnLL, FnANoIs FONTAINE.

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