Method and apparatus for acid granulation of matte

Patent metadata

Field	Value
Publication number	US-9777345-B2
Application number	US-201314650659-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Dec 20, 2012
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A method is provided for leaching the metals while granulating molten matte, comprising the steps of feeding a molten matte as a falling stream into a granulation chamber, spraying a liquid jet on the stream of molten matte to atomize the matte, and cooling the matte particles thus formed. The liquid jet comprises an acid solution containing water and sulfuric acid so that the acid solution starts leaching metals from the molten matte when the liquid jet contacts the molten matte. Part of product solution from granulation can be circulated to liquid jets to increase the metal content in the solution and to reduce its acid con-tent.

First claim

The invention claimed is:

1. A method for granulating molten matte, comprising the steps of feeding molten matte as a falling stream into a granulation chamber, spraying one or more liquid jets on the stream of molten matte to atomize the matte to form matte particles, and cooling the matte particles thus formed, wherein the liquid jet(s) comprise(s) acid solution containing water and sulfuric acid so that the acid solution starts leaching metals from the matte when the liquid jet contacts the molten matte.

2. A method according to claim 1 , wherein a product solution settling on the bottom of the granulation chamber is partly circulated to the liquid jet(s) and partly supplied to further steps of metal recovery.

3. A method according to claim 1 , wherein, in addition to said liquid jet(s), one or more jets of gas or steam is/are blown on the falling stream of molten matte to intensify atomization of the matte.

4. A method according to claim 3 , wherein solid particles are introduced into said gas or steam jets to intensify an effect of the gas or steam jet(s).

5. A method according to claim 1 , wherein hot gases are circulated in the granulation chamber to expand a temperature area suitable for leaching reactions.

6. A method according to claim 1 , wherein atomized matte particles are cooled at a lower part of the granulation chamber ( 30 ) by spraying a liquid jet of cooled product solution on the matte particles.

7. A method according to claim 1 , wherein the acid solution contains 5-50 g/l free sulfuric acid and 0-20 g/l metal sulfates and that a mass flow of the liquid jet(s) in relation to a mass flow of the molten matte is adjusted so that a final product settling on the bottom of the granulation chamber is essentially free of liquid phase.

8. A method according to claim 1 , wherein the acid solution contains 5-15 g/l free sulfuric acid and 0-20 g/l metal sulfates, and that the matte particles are separated from a product solution in or after the granulation chamber.

9. A method according to claim 1 , wherein the matte particles formed in the acid granulation are passed to further steps of metal recovery by leaching.

10. A method according to claim 1 , wherein the molten matte is nickeliferous matte, which also contains at least one metal selected from the group consisting of copper, cobalt, platinum group metals, gold and silver.

11. A method according to claim 1 , wherein off-gases generated during granulation and leaching are conveyed to a gas scrubber and an acid recovered by the gas scrubber is returned to the granulation chamber or neutralized.

12. A method according to claim 1 , wherein product solution generated during granulation and leaching is pumped to metal recovery carried out by solvent extraction.

13. A method according to claim 1 , wherein product solution generated during granulation and leaching is pumped to metal recovery carried out by precipitation.

14. A method according to claim 1 , wherein a product solution generated by extraction and separation steps is precipitated by an electrowinning process.

15. A method according to claim 14 , wherein at least one chemical selected from the group consisting of CaCO 3 , NaOH, H 2 S NaSH, and Ca(OH) 2 is used in the extraction and/or separation steps.

16. An apparatus for granulating molten matte, comprising a granulation chamber, an inlet feeding a stream of molten matte into the granulation chamber, at least one atomizing nozzle for spraying a liquid jet on the stream of molten matte to atomize the matte, wherein the liquid jet comprises an acid solution containing water and sulfuric acid so that the acid solution is able to start leaching metals from the matte as soon as the liquid jet contacts the molten matte and a gas recirculation line that circulates hot gas in the granulation chamber to extend the area of optimal reaction temperature.

17. An apparatus according to claim 16 , wherein the apparatus further comprises a discharge channel for conveying off-gas from the granulation chamber or lines from a basin-containing a product solution generated in the granulation chamber to a gas scrubber for removing acid gases from the off-gas and for recycling the acid gases back to the process.

Assignees

• Outotec Finland Oy

Inventors

• Hietala Kari
• Ranki Tiina

Classifications

• Y02P10/20

  Recycling · CPC title

• C25C1/20

  of noble metals · CPC title

• C22B23/025

  with formation of a matte or by matte refining or converting into nickel or cobalt, e.g. by the Oxford process (leaching of mattes C22B23/04) · CPC title

• C22B7/007

  by acid leaching · CPC title

• C22B23/0415

  with acids or salt solutions except ammonium salts solutions · CPC title