4,029,741 Recovery of antimony sulfides

Patent Number/Link:

United States Patent [19]

Coltrinari

[11 ]

[45j

4,029,741

June 14, 1977

9 Claims, 1 Drawing Figure

3,911,078 10/1975 Nadkami et at 423/87

Primary Examiner-G. R..Vertit

Assistant Examiner-Wayne A. Langel

Attorney, Agent, or Firm-Woodhams, Blanchard and

Flynn

A process is disclosed for separating antimony sulfides

from solutions comprising anitfftbny sulfides and arsenic

sulfides by subjecting the soiution to partial oxidation

within prescri,bed pH limits in order to oxidize

and precipitate a substantial portion of the antimony

sulfides while leaving substantially all of the arsenic

sulfides in solution.

[57] ABSTRACT

[56] References Cited

UNITED STATES PATENTS

2,348,360 5/1944 Reed 423/87

[54] RECOVERY OF ANTIMONY SULFIDES

[75] Inventor: Enzo L. Coltrinari, Arvada, Colo.

[73] Assignee: Tajima Roofing Co., Ltd., Tokyo,

Japan

[22] Filed: Mar. 1, 1976

(21] AppI. No.: 662,597

[52j U.S. CI 423/179; 423/87;

423/561 R

[51] Int. CI.2 , COlD 29/00

[58] Field of Search 423/87, 617, 561 R,

423/179,202

FEED

Noz5

TO LEACH

u.s. Patent June 14, 1977

FEED

4,029,741

02 AUTOCLAVE

OXIDATION

(NoOH) (PARTIAL)

FI L TRATI(;)N

N02S f As/Sb ISCRUBBER ::

H2S

SULFIDE f---H2SOf

t PRECIPITATION

NoOH

FILTER

H2O

AIR

EVAPORATION

8 ROAST S02

CARBON

FURNACE

N02S

TO LEACH

As/Sb ISb SULFIDEI

SULFIDES

5Na.SbS.+ 120. + 3H.0 ..... 2SboS. + NaSb(OH).+

7NaoS.0.

these values as antimony sulfides,thereby separating

these antimony values from the arsenic values in solution.

The thioantimonate compounds are reacted with

oxygen in order to produce insoluble antimony sulfides

5 and under some circumstances possibly minor amounts

of sodium hydroxyantimonate and sulfur, along with

soluble arsenic compound!" soluble sodium thiosulfate

and possibly some other non-sulfate sodium· salts.

Hence, the primary reaction is believed to be:

4,029,741

UTILITY OF THE INVENTION

SUMMARY OF THE INVENTION

DESCRIPTION OF THE PREFERRED

EMBODIMENTS

BRIEF DESCRIPTION OF THE DRAWING

RECOVERY OF ANTIMONY SULFIDES

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the treating of

solutions to obtain antimony values, ~d more particularly

to recovering these antimony values. as antimony

sulfides. .

The Prior Art

Numerous ore bodies exist which possess· considerable

amounts of arsenic and antimony, and various

processes have been developed to recover these values.

These processes are primarily dependent upon the While these prOducts are representative of .the types

primary recovery mechanisms employed for recovering 15 known to. be f?rmed, the only produc~ of pnmary II?-

the more abundant mineral values in the ore bodies. portance IS antimony sulfide. The arsemc values remam

U.S. Pat. No. 2,348,360 to Reed discloses a method of in solution, permittiI}g the antimony sulfides to be rerecovering

minerals from ores comprising copper, his- cover~d by filtering or other conventional separation

muth, tin, mercury, antimony, arsenic, and others by techmques.. '.' .

leaching the ore and solublizing the various metal sul- 20 The starting .soluti?ns sUltab~e for. ada~tation to the

fide components, and then· sequentially oxidizing the pr?Cess of the mvention compnse thl?~timonatesand

various metal sulfides by means of air and sulfur diox- thloarsenates. These v.alues. ma~ eXist m ~ more. reide.

The metal sulfides are then recovered by means of duced form, such ~ thioantimomtes and ~o~emtes,

precipitation and flotation. and under the~e CIrcumstances the. solution 18 prefer-

U.S. Pat. No. 1,528,004 to Bassett describes a proc 25 ably treated Wl~ ele~ental sulfur m. order to convert

cess for recovering arsenic from complex arsenic sul- them t? the thioantimonate and thioarsenate. forms,

fides by roasting the ore in the presence ofsufficient air ~espectlvely. Th~ forms of the salts are not partiCUlarly

in order to oxidize the arsenic to arsenus oxide while Important, and mclude, for example, sodIUm, potasminimizing

any oxidation of the sulfur. . sium, ammonium,. and ?ther s~ar cations. For the

No process is known which is capable ofhighlyselec- 30 purposes of th~ disCUSSIO~ heremafter presented, the

tive recovery of antimony sulfides from solutions which sodium form will be descnbed.

comprise antimony sulfides and arsenic sulfides. The Other components may also be present in the soluprocess

of the present invention effects such a separa- tion, and while their presence will be reflected in the

tion, and thereby prOduces a valuable prOduct from final products, the antimony/arsenic separation may

what is generally considered to be a waste product 35 still be accomplished. The solution is preferably an

stream. aqueous solution.

Such a solution may be derived from a number of

sources, including from leached solutions of various

The process of the present invention separates and hydrometallurgical processes designed to prOduce such

prOduces relatively· pure antimony sulfides from the 40 primary metals as copper and nickel. Antimony and

hereinafter set forth starting materials, and these anti- arsenic often exist in minor amounts in various ore

mony sulfides can then be conventionally convertedto bodies, and hence when such primary values are reantimony

oxides, a basic raw material for many prod- moved from the solution, the process of the present

ucts. invention may be employed to separate the antimony

45 from the arsenic remaining in the solutions. Also, antimony

may be the primary element to be recovered

A process is disclosed for recovering antimony sul- from various ore bodies, and the process of the present

fides from aqueous solutions comprising thioantimony invention may be employed in the course of this recovcompounds

and thioarsenic· compounds by subjecting ery. The concentration of the starting materials is not

the solution to selective oxidation by reacting the thi- 50 particularly important to effect the desired separation,

oantimony compounds with sufficient oxygen so as to although the process may be conducted more effimaintain

a final solution e.m.f. and pH within pre- ciently if the thioantimonate concentration in the startscribed

limits in order to oxidize and precipitate a sub- ing solution is from about 20 to about 80 grams per

stantial portion of the thioantimony compounds as .liter, and preferably from about 40 to about 60 grams

antimony sulfides while leaving substantially all of the 55 per liter. Also the concentration of thioarsenate is not

thioarsenic compounds in solution. important as the purity of the final antimony sulfide

product may be controlled by recycling this product

stream back to the oxidation step until the desired

purity is attained. In order to obtain a final antimony

60 sulfide product possessing less than about 0.4% arsenic

and recovering 95% of the antimony in solution, the

ratio of the antimonate concentration to the arsenate

concentration should be maintained at at least about

about two to one.

65 The amount of oxygen consumed during the reaction

is critical to the antimony-arsenic separation. If insufficientoxygen

is provided, the antimony recovery will be

adversely affected. If too much oxygen is provided, all

The FIGURE illustrates a simple process flow diagram

for· the separation of antimony sulfide from antimony-

arsenic sulfide solutions, along with the regeneration

of sodium sulfide.

The process of the present invention· is primarily

concerned with the oxidation of thioantimonate compounds

in solution in order to selectively precipitate

EXAMPLE 5

EXAMPLE 4

EXAMPLE 3

EXAMPLES

EXAMPLE 1

Again, the procedure of example 1 was followed,

with an initial solution concentration of 75 grams per

liter antimony and 1.3 grams per liter arsenic, providingan

antimony/arsenicratio of 58:1. The temperature

65 was maintained at 115° C, the pressure at 75 psig, and

the resultant product pH was 7.6. 0.63 pounds of oxygen

were consumed per pound of antimony precipitated.

99% of the initial antimony in solution was pre-

The procedure of example 1 was again repeated with

an initial solution concentration of 76 grams per liter

antimony and 1.3 grams per liter arsenic, these values

existing as sodium thioantimonate and sodium thioarsenate,

respectively. The reaction conditions were 112°

C, 75 psig, and the resultant product pH was 9.8. 0.58

pounds of oxygen were consumed per pound of anti-

55 mony precipitated. 94% of the initial antimony was

precipitated and 5% of the initial arsenic was precipitated.

The fmal precipitate analysis was 63% antimony,

0.05% arsenic, 23% total sulfur, and 3.6% sodium.

The procedure of example number 1 was repeated

with an initial solution concentration of 40 grams per

liter antimony and 14.8 grams per liter arsenic, providing

an antimony/arsenic ration of 2.7/1. The reaction

temperature was maintained at 100° C, the pressure at

70 psig, and the resultant product pH was 9.5. 0.79

pounds of oxygen was permitted to be consumed per

pound of antimony precipitated. The precipitate analyzed

65% antimony, 0.17% arsenic, 25% total sulfur

30 and 1%sodium. 60% ofthe initial antimony was precipitated

and 0.4% of the arsenic was precipitated.

4,029,741

or part of the arsenic will also be oxidized, and the

antimony-arsenic separation will not be accomplished.

The preferred amount of oxygen consumed by the

reaction when the reactants are thioantimonate and An aqueous solution comprising sodium thioantithioarsenate

and there are no additional compounds 5 monate and sodium thioarsenate, having an antimony

competing for the oxygen is such that the fmal solution

e.m.f. is preferably from about 300 to about 500, more concentration of about 49 grams per liter and an arpreferably

from about 350 to about 430, and most senic concentration of 2.66 grams per liter (an antimopreferably

from about 390 to about 410 millivolts, ny/arsenic ration of about 18:1), was charged to an

measured with Platinum/saturated Calomel electrodes. 10 autoclave equipped with a turbine mixing device.Reac-

Based on this criteria, it is generally found that the tion temperature was maintained at 110° C and the

amount of oxygen consumed per pound of antimony reaction pressure was maintained at 45 psig. Oxygen

being treated is preferably from about 0.5 to about 1.5, was charged to the autoclave and permitted to be conmore

preferably from about 0.6 to about 0.9, and most su~ed at a rat~ C?f 0.57 pounds of oxygen per pound of

preferably from about 0.75 to about 0.85 pounds. 15 antm:lOny precIpItated. The resultant pH of~~ p~oduct

It is also critical to the effective operation of the solution was 10.4. The final product analySIS mdIcated

process that the pH be maintained within a range of that 92% of the antimony was precipitated, while only

about 7 to about 11, more preferably from about 7.5 to 2% of the arsenic was precipitated.

about 10, and most preferably from about 8 to 9. If the EXAMPLE 2

pH is permitted to fall below the minimum values, 20

precipitates other than antimony sulfides tend to be

produced, detrimentally affecting the product purity.

The solution pH may be maintained by adding, if necessary,

any suitable base, such as sodium hydroxide.

The temperature and pressure of the reaction are not 25

particularly important from the final product standpoint,

but do affect the rate of reaction. The reaction

does proceed at room temperature and atmospheric

pressure, although the rate is quite slow. Therefore, the

reaction temperature is preferably maintained from

about 25° C to about 200° C, more preferably from

about 500 C to about 1500 C, and most preferably from

about 90° C to about 120° C. The reaction pressure is

preferably maintained at at least about atmospheric Again the procedure of example 1 was repeated with

pressure, more preferably from about 20 to about 150, 35 an initial solution concentration of 37 grams per liter

and most preferably from about 40 to about 80 psig. antimony and 14.9 grams per liter arsenic, providing an

The reaction time is very fast, and within the pre- initial antimony/arsenic ratio of 2.5:1. The reaction

ferred temperature and pressure parameters. set forth pressure was maintained at 70 psig, the temperature at

above, the reaction time is not a factor. Hence, the 115° C, and the resultant product pH was about 9.3.

process may conveniently be conducted in either a 40 0.73 pounds of oxygen were permitted to be consumed

batch or continuous fashion. It is generally preferred to per pound of antimony precipitated. 82% of the initial

agitate the solution during the reaction in order to keep solution antimony was precipitated, while 0.6% of the

the oxygen well dispersed. arsenic was precipitated. The final precipitate analyzed

As was previously mentioned, the antimony product 64% antimony, 0.18% arsenic, 27% total sulfur and

stream may be redissolved and recycled in order to 45 0.8% sodium.

obtain an antimony sulfide product practically entirely

free of arsenic impurity.

Upon completion of the reaction, the prooduct

stream is filtered in order to separate the antimony

sulfide precipitate froom the product solution. The 50

antimony sulfide product is then of commercial value

and may be sold at this point, or futher conventionally

treated to produce antimony oxide, elemental antimony,

and other products. The product solution may

be further treated for the production of any other values

desired.

Sodium sulfide may be regenerated in conventional

fashion. One preferred technique is in accordance with

the scheme set forth in the FIGURE wherein the product

solution is treated with sulfuric acid to precipitate 60

the remainder of the arsenic and antimony sulfides and

produce hydrogen sulfide off-gas. The remaining acidified

solution is then evaporated to remove the water

and the remaining sodium salts are roasted in the presence

of air to produce sodium sulfate. This solium

sulfate is then reduced with a carbonaceous material in

a furnace to convert the sodium sulfate to sodium sulfide.

The sodium sulfide may then be recirculated.

4,029,741

Prod. Prec.

Assay %

Sb As

% of Total

Sb Left In

Soln.

Slurry ISb] in Prod.

pH Soln. (g./l.)

Slurry e.m.f.

(millivolts)

EXAMPLE 6

EXAMPLE 7

cipitated while 27% of the initial arsenic was precipitated.

The fmal product precipitate analyzed 66% antimony,

0.31% arsenic, 23% total sulfur and 2.5% sodium.

350 8.8 0.13 0.3 67 0.41

372 8.8 0.12 0.3 66 0.32

392 9.0 0.42 0.9 66 0.29

An aqueous solution comprising sodium thioanti- :i~ ::i i:~~ ::~ ~; g::i

monate and sodium thioarsenate having an antimony 42_8 9_.2 3_.6_8__~_8_.0 67__0_.0_91_

10 concentration of about 46 grams per liter and an' arsenic

concentration of about 16 grams per liter was What is claimed is:

continuously charged to 3 autoclave vessels connected 1. A process for recovering antimony sulfides from

an aqueous solution comprising thioantimony comin<

series, each of the vessels having a 3 liter capacity, at d d thi· d .. 15 poun s an oarsemc compoun s, compnsmg:

a flow rate of 5.1 liters per hour. The reaction tempera- subjecting the solution to partial oxidation by injectture

was maintained between about 1100 and 1150 C ing sufficient oxygen so as to maintain a final soluand

the reaction total pressure was maintained at 60 tion e.mJ. of from about 300 millivolts to about

psig. Oxygen was charged to the system at a rate of 0.81 500 millivolts,· measured with platinum/saturated

Calomel electrodes, while maintaining the product

pounds of oxygen per pound of antimony precipitated, 20 solution at a pH of from about 7 to about 11 in

resulting in a final solution e.m.f. of about 390 milli- order to oxidize and precipitate a substantial porvolts

measured with platinum/saturated Calomel elec- tion of the thioantimony compounds as antimony

trodes. The pH of the product solution was maintained sulfides while leaving substantially all of the thioarat

9.0, 99.1n70t 0 f the antt.mony m. the system was prec.l.p- 25 2 sTenhic compou.nfdsli'n so1lutiohn. . th thi .

. d d th . . al' . d' th • e process 0 c aIm w erem e oanttmony

ltate , an e precipItate an YSls m Icated at only compound is thioantimonate.

0.33% arsenic was present in the product precipitate. 3. The process of claim 2 wherein the thioantimonate

compound is sodium thioantimonate.

30 4. The process of claim 1 wherein the thioarsenic

An aqueous solution comprising sodium- thioanti- compound is thioarsenate.

monate and sodium thioarsenate having an antimony 5. The p~ocess. of cla!m 4 wherein the thioarsenate

. . compound IS sodIum thioarsenate.

con.centratlon of. about 46 grams per lIter an? an ar- 6. The process of claim 1 wherein the pH of the

semc concentration of about 16 grams per lIter was product solution is maintained from about 8 to about 9.

continuously charged to 3 autoclave vessels connected 35 7. The process of claim 1 wherein the reaction temin

series, each of the vessels having a 3 liter capacity, at perature is maintained from about 500 C to about 1500

a flow rate of about 5.1 liters per hour. The reaction C·S A I: " lfid fr

. . o' process lor recovenng anttmony su es om

temperature was mamtalned between about 110 and an aqueous solution comprising sodium thioantimonate

1150 C and the reaction total pressure was maintained 40 and sodium thioarsenate, comprising:

at 60 psig. Oxygen was charged to the system at varying subjecting the solution to partial oxidation by reactrates,

resulting in final solution e.mJ. values measured ~g sufficient oxygen so as to m~~ a final soluwith

platinum/saturated Calomel electrodes as given in tion e.~:f. of from about 3.00 mill~volts to about

. 500 millivolts, measured WIth platinum/saturated

the table belo.w. For ~ach of the gIVen e.~.f. values, the 45 Calomel electrodes, while maintaining the p~oduct

product solution pH IS set forth, along WIth the concen- solution at a pH of from about 7 to about II in

tration of antimony in the product solution, the per- order to oxidize and precipitate a substantial porcentage

of antimony in the product solution based tion of the sodium thioantimonate as antimony

upon the total amount of antimony in the feed solution, 50 s~des while.leavin~ substantially all ofthe sodium

. . . thloarsenate m solution.

and ~~ amo~nt ofanttmony and arsemc m the p~oduct 9. The process of claimS wherein the product solupreCIpItate,

gIven as a percentage of the total weIght of tion is treated for the recovery of sodium sulfide.

the precipitate: * * * * *

UNITED STATES PATENT OFFICE

CERTIFICATE OF CORRECTION

Patent No. 4,029,741 Dated June 14, 1977

Inventor (s ) E_n_z_o_L_o_C_o_l_t_r_i_n_a_r_i _

It is certified that error appears in the above-identified patent

and that said Letters Patent are hereby corrected as shown below:

On the first page, in item "[73]", the correct assignee is

Equity Mining Corporation, Vancouver, British Columbia, Canada °

~igncd and 5calcd this

Twenty-second .Day of November 1977

[SEAL]

Attest:

RUTH C. MASON

Attest;ng Officer

LUTRELLE F. PARKER

Act;ng Commissioner of Patents and Trademarks

;�7Mfr0�(D�-family: HiddenHorzOCR'>6. The process of claim 5 in which the silicon tetrachloride

is introduced into the coating chamber in a gas

stream.

7. The process of claim 6 in which the gas stream is

an air stream.

8. The process of claim 1 in which the coal particles

are coated in accordance with the following process

steps:

a. introducing coal particles into a coating chamber;

b. introducing silicon tetrachloride into the chamber

under conditions that will promote its combination

with water either introduced into the chamber in a

separate stream or derived from the coal itself to 35

;marg�4Pot0�(D�t;line-height: normal;mso-pagination:none;mso-layout-grid-align:none;text-autospace:none'>injected into the jacket for the heating cycle. The speed

of the agitator is that at which the particles are kept in

suspension and a homogeneous slurry is maintained. At

This example shows the process is effective for zinc

concentrates and shows the deleterious effect of zinc

and iron ions on yield.

EXAMPLE VII (See Example III)

About 270 grams of a concentrate produced by the

oxidation of chalcopyrite-containing sulfur 48%,chalcopyrite

12%, pyrite and other minerals 40%, was 50

washed, slurried in I liter of water and held at 135°C ±

5° for the times shown. The slurry was cooled and

screened on a 100 mesh U.S. Standard screen.

Test I Test 2 Test 3

Additive 2 gm NaOH 2 gm NaOH 2 gm NaOH

(.74 gm/lOO gm of (.74 gm/lOO gm of (.74 gm/lOO gm

feed) feed) of feed)

Time 30 min. 60 min. 235 min.

Product

(o/c sulfur) 88.5 90.9 86.7

Yield (%) 23.0 19.0 59.0

This example shows that while a ,small amount of 65

coalescence occurs very quickly that times in excess of

I hour are necessary to obtain a high degree of coale~cence.

the end of the heating cycle, steam was shut off, cooling

water was admitted to the jacket, the autoclave cooled

down, and when the temperature dropped below 80°C

the' agitator was slowed down, the bottom valve opened

and the autoclave 'dischargedtoa screen. The sulfur

3,939,256

product was removed as the oversize + 65 .mesh, and

the fine materials or the tailings proceeded on to a

thickener. The sulfur product averaged around 96%

elemental sulfur with a recovery of over 85%. The

particles were greenish-yellow in color and irregularly 5

shaped.

What is claimed is:

l. A process for the recovery of elemental sulfur

from mixtures in which it is present with soluble calcium

compound impurities which comprises: 10

a. contacting the mixture with water to solubilize

calcium ions;

b. separating the solids content of the treated mixture

from the liquid content and washing the solids

content to remove said solubilized calcium ions

from the solids content;

c. forming a water slurry of said solids content;

d. adding to the slurry a surface modifying additive

selected from the group consisting of alkali metal

hydroxides, alkali metal carbonates, and mixtures

thereof to produce an alkaline slurry pH of at least

about 9;

e. heating the slurry to at least the melting point of

sulfur for a period sufficient to coalesce substantially

all of the sulfur particles, and

f. recovering the coalesced sulfur from the slurry.

* * * * *