IL41761A

IL41761A - Recovery of zinc

Info

Publication number: IL41761A
Application number: IL41761A
Authority: IL
Original assignee: Anaconda Co
Priority date: 1972-04-10
Filing date: 1973-03-13
Publication date: 1976-03-31
Also published as: BR7302500D0; DE2317332B2; ZA731753B; BE797954A; DE2317332A1; ZM5473A1; DE2317332C3; IT980742B; JPS4935222A; PH12395A; FR2179773B1; NO137758B; CS170470B2; IE37509B1; JPS5540648B2; SE407236B; AR200578A1; CA995905A; NL7304664A; NO137758C

Abstract

The ore contg. the metal as a sulphide is treated by froth-flotation to form a primary concentrate. which is suspended in an aq. soln. contg. ammonium sulphate and free NH3 and vigorously agitated at 50-80 degrees C and at 0.7 bar gauge in the presence of circulating free O2, the soln then being sepd. from undissolved solid and treated to recover the metal, and undissolved solid being submitted to a sec. flotation to produce a sec. concentrate which is treated to recover the metal. The process only requires low temp. and atmos. pressure. The sec. concentrate is of improved quality and is reduced in quantity. [FR2179773A1]

Claims

41761/2 ^ WHAT 18 CLAIMED IS J

1. The method of recovering zinc from aulfidic minerAle thereof which comprises forming a slurry of said minerals in a finely divided form in an aqueous solution containing ammonium sulfate and free ammonia> passing said slurry at a pressure below that requiring use of autoclave equipment into a closed leaching vessel* maintaining the temperature of the slurry in the range from 60°C. to 100*C, and withdrawing from said vessel slurry containing zinc complexed with ammonia dissolved in the aqueous phase and mineral matter depleted in zinc in the solid phase* characterised in that the body of the slurry in said vessel Is agitated with a vigor input of at least 0*05 horsepower per cubic foot while introducing oxygen into the agitated slurry at a substantial depth below the surface of said body.

2. The method according to Claim 1 wherein oxygen-bearing gas is continuously recirculated from above the body of agitated slurry into said body at a substantial depth below the surface of such body.

3. * The method of Claim 2 wherein the leaching operation Is conducted by passing the slurry sequentially through a series of leaching vessels*

4. The method according to any of the preceding claims wherein the concentration of free ammonia in the leaching vessel is correlated with the slurry temperature in such vessel to maintain the partial pressure of ammonia plus the partial pressure of water vapor in such vessel at lease several pel below the total pressure therein*

5. · The method according to any of the preceding .claims wherein the aulfidic sine minerals are flotation concentrates containing sphalerite * wurssite, marmatlte, or prlbramlte*'

6. * The method according to any of the preceding claims wherein the pressure maintained In the leaching vessel is below 10 pslg and preferably is in the range from 3 to 8 pslg. 41761/2 '

7. ·! The method According to any of the preceding claims wherein the slurry in the leaching vessel is agitated with a vigor input of at least 0.1 horsepower per cubic foot.'

8. The method according to any of the preceding claims, wherein the retention time of the slurry in the leaching vessel or vessels is from 3 to 9 hours.

9. Tke method according to any of the preceding claims wherein the aqueous phase of the slurry is maintained at a pH in the range from 9 to 11 throughout the leaching operation.

10. The method according to Claim 3 wherein the temperature of the slurry in the first leaching vessel in the series is maintained in the range from 70°C. to 85°C. and is increasad by several degrees C. in each subsequent vessel of the series*

11. The method according to Claim 10 wherein the zinc minerals are in the form of a lotation concentrate containing a high proportion of sphalerite, the temperature o the slurry in the first leaching vessel is maintained in the range from 70,oC. to 85°C, and the slurry is discharged from the last leaching vessel at a temperature in the, range from 90°C. to lOO'C. 1

12. The method according to any of Claims 3» 10, o 11 wherein the aggregate amount of free ammonia added to the slurry in the first reaction vessels of the series does not substantially exceed the amount consumed therein, whereby slurry passing from such vessels and entering the subsequent reaction vessels in the Series is substantially depleted in the free ammonia, and additional free ammonia is added . to the slurry in such ;' subsequent vessels at a rate not substantially exceeding its rate of consumption therein.

13. The method according to Claim 12 wherein the temperature of I the slurry in the last reaction vessel exceeds 90*C. and the free ammonia partial pressure therein is less than 3 pel. 41761/2 >*

14. » The method according to any of the preceding claims* wherein the slurry withdrawn from the vessel or vessels is cooled and free ammonia is added thereto prior to completion of the separation of the solution from the undissolved solids*

15. · The method according to Claim 14 wherein the slurry withdrawn from the reaction vessel or vessels in the series is at a temperature above 90*C. and is substantially depleted in free ammonia* and such slurry is cooled to below 80*C» and free ammonia is added thereto prior to separating the zinc-bearing solution from the undissolved solids*

16. The method according to any of the preceding claims wherein the solids containing residual undissolved sine separated from the zinc-bearing leach solution are mixed with aqueous ammonium sulfate solution containing free ammonia and are subjected to. a secondary leaching operation at a pressure not exceeding 10 psig. in a closed releaching vessel at substantially the some pH as and at a higher temperature than that prevailing on the average in the series of leaching vessels during the primary leaching operation while vigorously agitating the slurry in said leaching vessel and while admitting oxygen thereto and vigorously recirculating oxygen-bearing gas from above the body of slurry in said vessel into said body at a substantial depth below its surface* and thereafter separating the zinc-bearing aqueous phase from the zinc-depleted solid phase*

17. * The method according to Claim 16 wherein the secondary leaching operation is continued for a period of time longer than the duration of the primary leaching operation.

18. · The method according to either of Claims 16 or 17 wherein the secondary leaching operation is conducted in a single vessel*

19. * The method according to either of Claims 16 or 17 wherein the secondary leaching operation is conducted by passing the slurry sequentially through a series of vessels in the first of which the fr mmoni ar ial r ssure i i her and the temerature is lower 41761/2 £··

20. The method according to Claim 16 wherein the temperature of the slurry during the secondary leach is about 95°C.

21. The method according to any of the preceding claims wherein the separated zinc-bearing solution from the leaching operation is treated co produce metallic sine and to recover aqueous anmonlum sulfate solution* and said recovered aqueous solution is utilised to form additional slurry with sulfldlc zinc minerals to be leached.'