Method for treating lead anode slime

Patent metadata

Field	Value
Publication number	US-9650695-B2
Application number	US-201415038198-A
Country	US
Kind code	B2
Filing date	Nov 19, 2014
Priority date	Nov 21, 2013
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

The present invention relates to a method of treating lead anode slime having high fluorine and arsenic content, in particular to a method comprising smelting of the lead anode slime and cleaning the produced off gases in a one or more wet gas cleaning stages.

First claim

The invention claimed is:

1. A method of treating lead anode slime, comprising the steps of:
(a) providing a feed mixture comprising lead anode slime;
(b) smelting the feed mixture in a smelting furnace at a temperature above 1000° C. to smelt the feed mixture and to volatilize and remove at least part of antimony (Sb), fluorine (F) and arsenic (As) comprised in the feed mixture to obtain a first metal phase, a lead (Pb) slag and first process gas comprising volatilized Sb, F and As;
(c) cleaning the obtained first process gas in a venturi scrubber by contacting the said first process gas and a first venturi solution in the venturi scrubber to remove at least part of the Sb, F and As from the said first process gas to obtain a first cleaned process gas at least partly depleted of Sb, F and As and a second venturi solution comprising removed part of Sb, F and As;
(d) filtering at least part of the obtained second venturi solution to obtain a first venturi slime comprising Sb and a third venturi solution comprising F and As;
(e) adding a precipitation agent to the third venturi solution to precipitate at least part of F and As and filtering the precipitate to obtain a fourth venturi solution at least partly depleted of F and As and a F/As precipitate; and
(f) recycling the obtained fourth venturi solution to step (c) as a part of the first venturi solution.

2. The method as claimed in claim 1 , wherein the method further comprises the steps of:
(g) subjecting the first metal phase obtained in step (b) to oxidizing conditions to oxidize, volatilize and remove at least part of the remaining Sb, F and As and at least part of Pb comprised in the first metal phase to obtain a second metal phase, a first converting slag comprising Sb and Pb, and a second process gas comprising volatilized Sb, F, As and Pb; and
(h) introducing the obtained second process gas to the cleaning step (c).

3. The method as claimed in claim 2 , wherein the method further comprises the steps of:
(i) subjecting the second metal phase obtained in step (g) to oxidizing conditions to oxidize, volatilize and remove at least part of the remaining Sb, F and As and at least part of Pb comprised in the second metal phase to obtain a third metal phase, a second converting slag comprising bismuth (Bi), and a third process gas comprising volatilized Sb, F, As and Pb;
(j) cleaning the obtained third process gas in a venturi scrubber by contacting the said third process gas and a fifth venturi solution in the venturi scrubber to remove at least part of the Sb, F and As from the said the said process gas and to obtain a second cleaned process gas at least partly depleted of Sb, F and As and a sixth venturi solution comprising Sb, F and As; and
(k) filtering part of the obtained sixth venturi solution to obtain a second venturi slime comprising Sb and a seventh venturi solution comprising F and As.

4. The method as claimed in claim 3 , wherein the method further comprises the step of:
(l) diluting the remaining part of the sixth venturi solution with process water to obtain a diluted venturi solution and recycling the thus obtained diluted venturi solution to the cleaning step (f) as a part of the fifth venturi solution.

5. The method as claimed in claim 3 , wherein the method further comprises the step of:
(m) buffering the seventh venturi solution and recirculating the buffered venturi solution to the cleaning step (c) as a part of the first venturi solution.

6. The method as claimed in claim 3 , further comprising the steps of:
(n) recycling the second venturi slime to the smelting step (b).

7. The method as claimed in claim 2 , wherein step (g) is accomplished by exposing the first metal phase to air.

8. The method as claimed in claim 1 , wherein the lead anode slime comprises 25 to 50% w/w Sb, from 0.5 to 5% w/w F and from 0.2 to 10% w/w As, and optionally from 0.2 to 20% w/w bismuth (Bi).

9. The method as claimed in claim 1 , wherein step (b) further comprises adding coke breeze to the smelting furnace after smelting of the feed mixture at a temperature above 1000° C. to complete the reduction of the obtained smelt.

10. The method as claimed in claim 1 , wherein feed mixture is added to the smelting step (b) in portions.

11. The method as claimed in claim 1 , wherein temperature of step (b) is from 1150 to 1200° C.

12. The method as claimed in claim 1 , wherein the precipitation agent in step (e) is calcium oxide (CaO), calcium hydroxide (Ca(OH) 2 ), calcium carbonate (CaCO 3 ) or a mixture thereof.

13. The method as claimed in claim 1 , wherein the feed mixture further comprise recycled dust and/or materials recycled from downstream process steps.

Assignees

• Outotec Finland Oy

Inventors

• Berg Gunnar
• Maliarik Mikhail
• Ögren Bert

Classifications

• C22B30/04 Primary

  Obtaining arsenic {(extraction of metal compounds by leaching in organic solutions C22B3/16; treatment or purification of solutions by adsorption on solids C22B3/24, by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42)} · CPC title

• C22B30/02 Primary

  Obtaining antimony · CPC title

• C22B7/04

  Working-up slag · CPC title

• C22B13/06

  Refining · CPC title

• C22B3/205

  using adducts or inclusion complexes · CPC title