3,853,981 Liquid ion exchange process for the recovery of metals

Patent Number/Link:

United States Patent [19]

Hadzeriga

[ 11 ] 3,853,981

[45] Dec. 10, 1974

10 Claims, 1 Drawing Figure

Primary Examiner-Herbert T. Carter

Attorney, Agent, or Firm-Sheridan, Ross & Fields

An ion exchange process for selectively recovering a

first metal in solution from a second metal without

build-up of the second metal in the circuit. The process

comprises first separating from the ion exchange

recovery circuit for the first metal a bleed stream of

the aqueous which is recycled to the leaching stage to

maintain a required concentration of first metal in the

leaching stage. The remaining aqueous is further contacted

countercurrently with barren organic to completely

remove all of the first metal from it. The aqueous

is then sent to a recovery circuit for the second

metal. After the second metal recovery the raffinate

from this stage is returned to the leaching stage. The

result is that the second metal is removed from the

system at substantially the same rate at which it is introduced

into the leaching stage in the continuous

process.

[54] LIQUID ION EXCHANGE PROCESS FOR

THE RECOVERY OF METALS

[75] Inventor: Pablo Hadzeriga, Arvada, Colo.

[73] Assignee: Cyprus Mines Corporation, Los

Angeles, Calif.

[22] Filed: June 26, 1972

[21] Appl. No.: 266,456

[52] U.S. Cl. 423/24, 423/32, 423/100,

423/109,423/105,75/103,75/101 BE,

75/117,75/120,204/106,204/114

[51] Int. CI... ..... COlg 3/00, COlg 3/10, COlg 3/14,

COlg 9/00, C22b 15/10, C22b 19/24, C22b 19/26

[58] Field of Search 423/24, 32, 33,109,100,

423/105; 75/100 BE, 101 R, 103, 117

[56] References Cited

UNITED STATES PATENTS

2,805,918 9/1957 Van Hare et al. 423/105

2,839,388 6/1958 Van Hare et al. 423/105 X

[57] ABSTRACT

I AMMONIUM I I FEED ~ CARBONATE IAIR OR OXYGEN I

SOURCE (SCRAP BRASS) SOURCE

~ I LEACHING 1

FEED

SOLUTION

1 PREGNANT ORGANIC I H2SO I 4 1-- STRIP

STAGE I

ION EXCHANGE

BLEED AQUEOUS

STRIP

RECYCLE ORGANIC BARREN LIQUOR

ORGANIC

STAGE 2

ION EXCHANGE I COPPER }- ELECTROLYSIS

AQUEOUS ORGANIC

STAGE 3

ION EXCHANGE

AQUEOUS

ZINC RECOVERY

DEHPA EXTRACTION

OR PRECIPITATE WITH

C02 OR BY BOILING

OFF NH3

RAFFINATE

RECYCLE

SPENT ELECTROLYTE

RECYCLE

AMMONIUM

CARBONATE

SOURCE

BLEED

RECYCLE

FEED

(SCRAP BRASS)

LEACHING

FEED

SOLUTION

STAGE 1

ION EXCHANGE

AQUEOUS

STAGE 2

ION EXCHANG E

AQUEOUS

STAGE 3

ION EXCHANGE

AIR OR OXYGEN

SOURCE

PREGNANT ORGANIC

I~RGANIC IBARREN

ORGANIC

H2S04

STRI P

STRIP

LIQUOR

. COPPER

ELECTROLYSIS

SPENT ELECTROLYTE

RECYCLE

:r>

.-..l,

:z:

.-..l,

C'"

C-.E. ~

RAFFINATE

RECYCLE

AQUEOUS

ZINC RECOVERY

DEHPA EXTRACTION

OR PRECIPITATE' WITH

C02 OR BY BOI LIN G

OFF NH3

wc.o'

t-J

3,853,981

The operation of the invention is described with reference

to the accompanying drawing of the flow sheet.

solution is prevented and commercial grade copper and

zinc are recovered in quantitative amounts.

Copper is extracted with a copper selective ion exchange'

agent from· an ammoniacal leach solution of

5 scrap brass containing copper and zinc values. A prescribed

portion of aqueous from the copper extraction

step is recycled to the leach solution to maintain

enough cupric copper therein to expedite leaching.

Zinc build-up in the leach solutionis prevented by

sending the remaining aqueous to a zinc recovery circuit

where zinc is removed and the raffinate from this

stage recycled to the leaching stage. To insure maximum

copper recovery and that the recovered zinc is of

commercial grade and not contaminated with copper,

the remaining aqueous referred to above is contacted

in at least one countercurrent extraction stage with bare

ren organic for complete removal of copper before

reaching the zinc recovery circuit.

. BACKGROUND OF THE INVENTION

LIQUID ION EXCHANGE PROCESS FOR THE

RECOVERY OF METALS

The increasing world-wide scarcity of copper with

consequent increase in price has stimulated a demand

for an economical process for recovering copper from

scrap brass and other copper alloys. The present invention

is related to a process for recovering copper from 10

ammoniacal solutions used to leach scrap copper al~

loys, particularly, brass and bronze.

The art for leaching copper from its ores and alloys

with ammoniacal solutions is well developed. For example,

it is known that a leach solution of 30 gil NH3 15

and 30 gil of (NH4h C03 will dissolve 40 gil of copper.

It is also well known that a certain amount of cupric

copper must be present in the solution to maximize the

rate at which copper is dissolved. Otherwise, without 20 DETAILED DESCRIPTION OF THE INVENTION

adequate oxidation, the metallic copper will reduce any

cupric ion present in solution in accordance with the

reaction: CUD+Cu++ +-:-"2 Cu+ and leaching will cease.

Therefore, during leaching. air or oxygen is bubbled

h h h I hi' ·d· h . The drawing isa schematic showing of the ion ext

ro~g t e eac so utlon to OXI Ize t e cuprous Ion to 25 change system in which an illustrative embodiment or

cupnc.

While ammoniacal leaching provides an effective application of the process is presented. This system was

means for solubilizing copper and zinc from scrap used in obtaining the results presented further on in the

brass, it is difficult to recover the copper from the leach specification. In the drawing a conventional liquid ion

solution in the presence of dissolved zinc. exchange circuit for the recovery of copper from an

Most of the ion exchange extractants for copper are 30 ammoniacal leach solution is represented followed by

not sufficiently selective for copper to permit their use a conventional sulfuric acid stripping circuit followed

for effectively separating this metal in solution in the by an electrolysis step forelectrowinning copper. A

bleed recycle of a portion of the aqueous from the first

presence of other metals. However, the General Mills copper recovery stage to the leaching stage is shown

Company of Minneapolis, Minn. has introduced on the 35 with another portion of the aqueous going through two

market some copper ion exchange agents sold under a~ditional copper recovery stages before proceeding to

the names of LIX-63, LIX-64, LIX-64N, LIX-65N a zinc recovery circuit:The direCtion of the arrows inand

LIX-70 which are highly selective to copper. One dicates the countercurrent travel of aqueous and orof

the active agehts of some of t~ese extractants, LIX- ganic phases..

-64 an~ LIX-6~N, for ~xample, IS a 2-hydroxy benzo- 40 In the description which follows the combination of

phenoxlme as dlsclosed.In U.S. Pat. No: 3,42~,449. AI- the first ion exchange stage, the H2S04 strip and the

th?ugh ~he problem whIch ~he present InventIon solves copper electrolysis will be referred to as the copper reanses

WIth the use of selectIve extra.ctants~ the extra~t- covery circuit, while ion exchange stages 2 and 3 with

ants .themselves fo:m ~o Par.t of the InventIOn as .the In- the zinc recovery· stage will be referred to as the zinc

ventlOn fl.nds apphcatlon WIth the use of selectIve ex- 45 recovery circuit. The recycle of the aqueous bleed from

tractants.In g~neral. . stage 1 is referred to as the bleed recycle and the recy-

The chIef dlsadvanta~e of the use of selectIve sol~ent c1e of the raffinate from the zinc recovery stage is reextra~

t~nts ~or separat~ng cop~er ~alues from solutl?ns ferred to as the raffinate recycle, the main stream of the

con.tammg zmc value~ IS that .zmc If not .removed bUIlds 0 aqueous proceeding through stages 1, 2 and 3.

up m th~ lea~h solut~~n durIng a contmu~us proc~s~. 5 The leach solution comprises copper and the zinc

Upon dlssolvmg addItIOnal copper, the zmc preclpl- values dissolved in an ammoniacal solution containing

tates as a basic carbonate and coats the surface of un- about equal amounts of ammonia or ammonium hydissolved

scrap, thus retarding further copper solution. droxide and ammonium carbonate. An ammonium car-

Various expedients to combat this, such as agitation bonate source is available to adjust the composition of

leach, have been resorted to by the prior art. 55 the leaching solution. Each of the stages 1, 2 and 3 in-

Accordingly, it is a principal object of the invention c1udes a conventional mixer-settler system to perform

to provide an ion exchange process,for the selective re- the separation.

covery of a first metal in solution with a second metal The organic solvent was prepared using the abovein

which build-up of the second metal in the leach solu- 60 mentioned extractants dissolved in an inert diluent,

tion is prevented. such as Napoleum 470, a hydrocarbon distillation frac-

Another object of the invention is to provide an ion tion. Other conventional organic diluents may be used.

exchange process as stated for the principal object in The concentration of extractant in the solvent will dewhich

both metals are recovered in commercial grade pend on the desired characteristic of the circuit.

purity. 65 Air or oxygen is introduced in the leaching step to ox-

A further object of the invention is the provision of idize copper to the cupric form to increase leaching

an ion exchange process for the recovery of copper in rate. The feed solution goes to stage 1 where more than

solution with zinc in which build-up of zinc in the feed 50% of the copper is extracted into the organic phase.

3,853,981

GIL

34 - 35

9.5 - 9.7

40 - 55

21.4 - 21.6

NH. co.

COMPONENT

The aqueous feed for the results of Table 2 had a pH

of 10.4 and the following composition:

Cu(NHa).++ + 2(OH)- + 2RH + 2H20+---+ R2Cu + 4

NH.OH

The pregnant organic moving countercurrently to the so that for this reaction the-ammoniaieach sOlution is

aqueous phase goes to the sulfuric acid stripping circuit completely regenerated. However, some losses of amwhere

the copper is stripped and copper sulfate liquor monia and CO2 do occur during the operation of the

goes to electrolysis where metallic copper is recovered process. Losses of both gases are kept at a minimum by

at the cathode with the reformation of sulfuric acid 5 recycling the aqueous from the copper recovery circuit

which is recycled back to the stripping stage. The bar- and the raffinate from the zinc recovery circuit.

ren organic from the H2S04 stripping stage is diverted The process of the invention was performed in accorto

extraction stages land 3. dance with the flow sheet of the drawing. The results

A.portion of aqueous from stage I is recycled to the in terms of material balances set forth in Tables I and

leaching stage as a bleed for further dissolution of cop- 10· 2 below are representative of those obtained in prac- .

per. It is important to recycle a substantial amount of tice.

cupric copper to the leach solution as its presence max- The aqueous feed used for the results presented in

imizes the rate of leaching of copper from the brass Table I had a pH between 11.4 and 12 and the followscrap

as explained earlier. The amount of copper which 15 ing composition: _. __.... _..

must be recycled for a continuous process can be calculated

and a prescribed portion of the aqueous diverted

accordingly.

The remainderof the aqueous travels from stage 1 to

stages 2·and 3 where it is countercurrently contacted 20

with barren organic to provide an effective recovery of ---------------------

any copper remaining in this portion.

From stage 3 the substantially copper-free portion of

aqueous goes to the zinc recovery circuit where zinc is

recovered by conventional solvent extraction with di 25

2-ethyl hexyl phosphoric acid [DEHPA] or by precipitation

by addition of carbon dioxide or by boiling off

ammonia, procedures well known inthe art. Commer- ~~ 29.6

cial grade substantially copper-free basic zinc carbon- NHa

2~:~5

ate, zinc oxide or the metal is finally recovered by con- 30 co, 30.7

ventionalprocedures.---··....-----..--.------.-..--...---.

The raffinate from the zinc removal stage is recycled The organic phase for copper recovery consisted of

and mixed with the bleed stream of aqueous from the 10% LIX-64N, 5% isodecanol and 85% Napoleum 470

first stage for return to the leaching stage. The amount (volume percentages). The loaded organic was

of aqueous going to the zinc recovery circuit should be 35 stripped with a 200 gil H2S04 solution. The process was

sufficient for removal of a quantity of zinc equal to that operated at room temperature. The copper strip liquor

dissolved in the leaching stage. Contacting countercur- was fed to a small electrolytic cell whereby copper was

rendy the portion of aqueous from stage I going to the plated and the depleted electrolyte was recycled to the

zinc recov.ery circuit with barren organic in stages 2 stripping circuit.

and 3 before zinc recovery insures removal of substan- 40 In the . . . . d f: ZInC reco~ery cIrcuIt zmc was extracte rom

tially all of the copper with the result that the zinc re- the aqueous by usmg DEHPA. (10% DEHPA, 5% Isocovered

meets commercial grade specifications. The decanol, 85% Napoleum ~70 10 v?lume percentages).

barren organic is more effective for removal of the re- T,he loaded solvent was stnpped WIth 30 gil H2S04 and

maining copper in the aqueous than partially loaded or- 45 zmc recovered from the ZInC sulfate formed by stanganic

dard procedures.

Am'monia and carbon dioxide losses are a consider- !he test from which the ~esults of Table 1 were ob-

. .. tamed was operated contmuously for twenty hours

atlon for a commercIally feasIble process and they must h'I' th t t ~ th It f T bl 2 th

be held to a minimum. The reaction involved in the ex- w I e In e es or ~ resu s 0 a e e process

t f . ti th f' was also operated contmuously for twenty-seven hours.

rac Ion process or e recovery 0 copper IS: 50 At the end of each test complete analyses were performed

across the unit and material balances for the

last hour of operation were obtained. These material

balances are presented in Tables 1 and 2.

TABLE 1

COPPER

In: Cu 34.5 gIl 500 mllhr = 17.25 g

Out: Bleed recycle IS.5 gil 400 ml/hr = 6.20g

Strip 41.0 gil 240 mllhr = 984 1

17.04 11 VB. 17.25 g in feed

98.8% accounted for

ZINC

In: Zn 9.67 gIl 500 ml/hr~ 4.84 g

Out: Bleed recycle 9.20 gil 400 ml/hr = 3.68 g

Strip Zn 4.19 gil 100 ml/hr = 0.42 g

Strip Cu 0.11 gIl 240 mllhr = 0.03 g

Rafftnate 0.01 gIl 100 ml/hr =

4.13 g '5. 4.84 g in feed

85.3% accounted for

3,853,981

TABLE 2

In: Cu

Out: Bleed recycle

Strip

29.6 gIl

16.4 gil

32.8 gIl

COPPER

500 ml/lIr = 14.80 g

400 ml/hr = 6.56 g

240ml!hr=~

14.43 g vs. 14.80g in feed

97.5% accounted for

In: Zn

Out: Bleed recycle

Strip Zn

Strip Cu

Raffinate

9.15 g/I

9.15 gil

4.19 gil

0.91 gil

5.64 gIl

ZINC

500 ml/hr = 4.58 g

400 mllhr = 3.66 g

50 ml/hr = 0.21 g

240 mllhr = 0.22 g

100 ml/hr = 0.56 g

4.65 g vs. 4.58g in feed

101.5% accounted for

f. stripping copper from said ion exchange agent with

a stripping agent for copper,

g., recov~rin,g copper from the stripping agent, and,

h. recycling the barren ion exchange agent from step

(f) to step (a) after contacting it with said remainderof

a9.11eous pl1ase.

9. A continuous countercurrent ion exchange process

for the selective recovery of copper and zinc from

an ammoniacal ammonium carbonate leach solution in

. which process the cupric-cuprous ratioof the leach solution

is maintained at an active leaching level and the

30 copper is recovered in the presence of zinc without

build-up of zinc in the leach solution, the process comprising

the following operations performed continuously

and simultaneously with the aqueous and organic

phases passing countercurrent to each other:

a. continuously adding copper and zinc containing

feed to the leach solution in a leaching stage to provide

an aqueous phase containing copper and zinc

ions,

b. flowing said aqueous phase to a first copper recovery

stage and recovering copper from said aqueous

phase by ion exchange by contacting said aqueous

phase countercurrently with a water immiscible organic

phase comprising a copper selective ion exchange

agent in an organic diluent,

c. recycling a bleed portion of said aqueous phase

from the first copper recovery stage of step (b) to

the leaching stage to maintain the cupric-cuprous

ratio of said leach solution at an active leaching

level,

d. passing the pregnant organic phase to a copper

stripping stage to strip copper from the organic

phase leaving the organic phase substantially barren,

e. recycling the barren organic phase to said first copper

recovery stage where it is again loaded with

copper,

f. passing the remainder of said aqueous phase to a

zinc recovery stage to recover zinc therefrom at a

rate substantially equal to the rate of addition of

zinc to the leach solution to prevent build-up of

zinc in the leach solution, and

g. recycling spent raffinate from said zinc recovery

stage to said leaching stage,

whereby as zinc and copper are continuously

added to said leach solution the cupric-cuprous

ratio in said leaching solution is continuously

maintained at an active leaching level and zinc is

continuously removed from said leach s,:!lution at

The results show that build-up of zinc in the leach solution

can be effectively controlled by use of the flow

sheet. The plated copper from the copper strip liquor 20

meets the commercial specifications for this metal. The

strip zinc solution was pure enough to warrant the recovery

of a basic zinc carbonate, zinc oxide or zinc

metal meeting commercial specifications.

What is claimed is:

1. A continuous ion exchange process for the selective

recovery of copper and zinc from an ammoniacal

ammonium carbonate leach solution in which zinc and

copper are continuously added to the leach solution

and recovered without build-up of zinc in the leach solution,

the process comprising:

a. contacting the leach solution in an ion exchange

circuit for copper with a water immiscible organic

phase comprising a copper selective ion exchange

agent in an organic diluent,

b. recycling a bleed portion of the aqueous phase

containing copper and zinc from the ion exchange

circuit to the leach solution to maintain the cupriccuprous

ratio therein at an active leaching level,

c. recovering zinc from the remainder of the aqueous 40

phase at a rate substantially equal to the rate of addition

of zinc to the leach solution to prevent buildup

of zinc in the leach solution,

d. recycling the raffinate from step (c) to the leach

solution, and

e. recovering copper from said organic phase.

2. The process of claim 1 in which said ion exchange

extractant is a benzophenoxime.

3. The process of claim 1 in which said zinc is recovered

from said remainder of the aqueous phase by .sol- 50

vent extraction with di 2-ethyl hexyl phosphoric acid.

4. The process of claim 1 in which zinc is recovered

from said remainder of the aqueous phase by boiling off

ammonia.

5. The process of claim 1 in which zinc is recovered 55

from said remainder of the aqueous phase by adding

carbon dioxide.

6. The process of claim 1 in which substantially all of

the remainder of copper is removed from said remainder

of aqueous phase before removal of zinc therefrom 60

and recycle of the barren raffinate to the leach solution.

7. The process of claim 6 in which the remainder of

copper is removed by contacting said remainder of

aqueous phase with barren organic phase resulting 65

from stripping copper from said ion exchange agent.

8. The process of claim 7 to which is added the following

steps:

3,853,981

a rate substantially equal to its rate of introduction

to prevent zinc build-up in the leach solution.

to. The process of claim 9 including at least one additional

copper recovery stage immediately following

said first copper recovery stage and the continuous

countercurrent circulation of said remainder of aqueous

phase and said barren organic phase therethrough

before the organic phase is returned to said first copper

5 recovery stage.

* * * * *