BE724214A - - Google Patents

Description

  

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  BELGIAN PATENT "Process for recovering cteo residues from lixviation of zinciferous materials".

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   The present invention relates to a process for upgrading the residues from the leaching of zinc-bearing materials with a view to recovering certain elements, mainly metals and in particular zinc.



   In the electrolytic process of zinc metallurgy, zinciferous materials such as roasted blends are leached in dilute sulfuric acid from electrolytic cells. During this operation, a non-negligible part of the zinc is not solubilized because it is involved in certain compounds which, such as in particular zinc sulphide and zinc ferrites (ZnOFe2O3), are insoluble under the conditions of leaching.

   This non-solubilized zinc; accompanied by other elements such as especially lead and silver, is found after settling and / or'filtration in a residue commonly called "leach residue". '
The leaching residue contains a whole series of elements: some.- are insoluble in sulfuric acid; among these cAO, Si O2, Al2O3, are considered as non-recoverable while Pb, Ag, Sn, Au, are recoverable; certain others reputed to be soluble in sulfuric acid are nevertheless found in the residue as a result of the operating conditions of the leaching; among these Zn, Cu, Cd can be upgraded;

   Fe, Mg, Cl, F, Na, K are considered as non-recoverable and As, Sb, Ge, Co, Ni are harmful for subsequent operations.



   Various processes are already known which make it possible to dissolve the soluble and recoverable elements mentioned above, to separate the insoluble recoverable elements and to eliminate the insoluble and even dangerous elements.



   The problem at the basis of the present invention is to provide a method of recovery from the leach residues, '

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 zinc and other elements that may or may not be recoverable.



   This problem is solved by the present invention which relates to a process in which the "leaching residue" is subjected to a subsequent leaching, at atmospheric pressure, at a temperature between 50 ° C. and the boiling temperature, using a dilute sulfuric acid solution, the concentration of free acid at the start of which is between 100g / 1 and 25Ug / 1 in an amount equal to 2 to 5 times the stoichiometric amount of acid necessary to dissolve the zinc contained in said leaching residue, which forms a sludge hereinafter referred to as a lead residue oomprising insoluble elements which can be recovered such as lead, silver and gold, mixed with a solution to which is then added,

   at a temperature between 50 0 and the boiling point, a sulphide ore, comprising in particular zinc sulphide, in an amount equal to 1.1 to 1.5 times the stoichiometrically necessary quantity for the reduction to the ferrous state of ferric iron present in said solution, a sulphurous residue is separated from said solution as gold:

     oxide and from which the iron contained therein is precipitated by using as a preferential oxidant the oxygen of the air necessary for the formation of iron oxide, at a temperature between 50 C and the boiling temperature and add a neutralizer containing zinc oxide such as roasted blende in the desired amount to maintain a pH of 1.7 to 3, so that the iron in precipitating carries with it other impurities such as arsenic , antimony, germanium and fluorine,
In the process according to the invention, the treatment of the solution before the iron precipitation phase can be carried out in several distinct phases;

     thus, it is possible to have a phase for leaching or dissolving the zinc with separation to the lead residue and a reduction phase with separation

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 of the sulphurous residue, The separation of the lead and sulphurous residues and of the iron-based precipitate is carried out in a known manner by any retort operation by filtration, by decantation or in any other manner.

   The lead residue can then be treated by the usual metallurgical methods to extract therefrom the insoluble valuable elements such as lead, silver, tin and gold which can thus be recovered; as for the sulphurous residue, it can be immediately treated in order to extract therefrom the elemental sulfur which it contains, and / or treated in roasting furnaces mixed with sulphurous ores.



   The way provided for in the invention to oxidize and then precipitate iron is particularly advantageous because it makes it possible to obtain a precipitate in the form of iron hydroxides hemihydrates, such as (Fe OOH) Ó and (FeOOH) Y, goethite and lepidocrocite, @
 EMI4.1
 which are = J; ililtrable or decanable cileiient; in this way, either all the difficulties encountered during the separation of a precipitate of ferric hyuroxide Fe (OH) 3 obtained, are eliminated,
 EMI4.2
 by neutralizing a solution of ferric sulphate to pH,;

   high while consuming less neutralizer, ie -. the loss of sulfuric acid and the addition of alkali in the case where, according to certain known methods, the iron is precipitated under the jaresite orb in a more acidic medium, ie an expensive and complicated apparatus in the case where the iron is precipitated under high pressure and high temperature. The sul-
 EMI4.3
 i'1.t!. 'i,: ailuted ue used "e ü: s the, treatment phase of the" C.0 leaching residue "for the dissolution of the zinc is, pr6:' er '-: e,, z. aci the acid coming from electrolysis solutions.} '\. m :::: 1. reduction, we use b.7't:

   euse :: 1st..t ase the raw blende. It was found during this operation that the sulphides,

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 zinc and copper preferentially dissolve over sulphides of Pb and Fe and this has interesting metallurgical yields. By this operation, it is therefore possible to separate and extract from the mixed ores, the zinc and the copper contained therein. Under the conditions of the invention, yields of reduction of ferric iron in solution are obtained, of between 95 and 100%.



   As for the oxidation phase, it should be noted that it is accelerated by certain catalyst elements, in particular copper and solubilized silica as well as activated carbon. It is always observed in the case of the treatment of leaching residues, the presence of copper at levels such that its catalytic action is sufficient. heavens,,
It should be noted that the treatment of the solution after reduction can be dissociated e / phase, the first phase consisting of neutralization of the free acid, the second being the operation of precipitation of the iron proper. ,
This neutralization can be carried out with roasted blende or another neutralizer;

   the residue from this neutralization can be advantageously treated in admixture with the leach residue in the first phase of the present process,
On the other hand, measurements of the settling and filtration rates of the iron precipitate were carried out. The following values were obtained: settling speed greater than 4 cm / min; filtration rate: 500 Kg / m2 / h of dry residue for a cake with a thickness of 10 mm and a vacuum of
500 mm Hg.



   In one embodiment of the invention, said oxidation and said precipitation are applied to a solution having

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 a density which can range from 1.20 to 1.50, an iron content of 50 g / 1 at most, the Fe3 + / Fe2 + ratio in this solution being less than 0.05, said solution containing more than 300 mg / 1 of . copper as catalyst and the particle size of the neutralizer being less than 200 mehs.



   The present invention will now be described in more detail but not limited to the following example which relates to a process carried out in three phases, namely a phase of leaching or dissolving the zinc, a reduction phase and a phase of neutralization oxidation and precipitation of iron.



    EXAMPLE 1st phase
45 liters of leach residue pulp containing 631 g / 1 of washed and dried solids were mixed with 200 liters of sulfuric acid from the electrolysis cells (return-cell). The mixture was stirred and kept for 6 hours at a temperature of 90-95 ° C. The plorabous residue and the solution were then separated therefrom. The various elements were measured in the products of the charge on the one hand and in the lead residue and the solution obtained on the other hand. The results are shown in Table 1 below, whereas Table 2 shows the balances of certain elements.

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   TABLE 1.
 EMI7.1
 
<tb>
<tb> Analysis <SEP> of the different <SEP> <SEP> products.
<tb>
 
 EMI7.2
 



  , ¯ ¯ ........., ¯ ..¯¯ ..



  Oharge: i {rodui ta obtained '16mént éSldU! of Filtrat Retour-ce2-: Réoldu 1 J,; Solufaou Jixiviation; ! acco: nra;.; n '-' l-: t lu1e (liq.! plor: lbeux: finale .1j va le residue ue 'Prov. üe lixiviatiOl1 c el, Ul eq..tro1! -.). ¯ - ----- L ---- 1 total 20 21 5 160 1 1 48 é 1 1 3, a '> 1 85, 2 - /: 1 1 soluble Tï2U I' 0.19% l 1 0.32 '1 zf, r: oy) &, 6 15.95 2C ,, 7 <# / L He! .



  I: e, 419.71] i., 0.12; 330 ra4 / i, 1 - v, C3 ;; G, 1,: / z, II; 1.26 ': 380 4/1 i - 0, l-: 1.47;, / 1.



  1 0.15 î5 - 1 - 0, 4 '/ e) 0, 00 4e) 1,! 0.56mg / ll 0.01 m, j / 1 'O, 34:! >, BG ::, ./1 s Gf24 I 0.5 mg / 1 0.1251: 1,; / 1. O, Ub I 2j, 4t: .l. b 0.06 µl, 6 mC / 10 01,:; / 1 0.046 i 30 m; ; / J.



  ,; 320 g / t - 720 {!, / T, 1 2 so 4 0 g / l 162 dl ¯.¯ ..... ¯ .--. ¯.¯ ...... J Weight of washed lead residue and dried = 35.1% 55.1% Weight of washed and dried leaching residue The yield of solution of Zn, that is to say the amount of insoluble Zn which has been solubilized is equal to: insoluble of / Zn insoluble from the ore leach residue - Zn 'lead residue
 EMI7.3
 -------------------------------------------------- ------------.

   Zn insoluble residue from leaching ore 93.1%

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 TABLE 2 Balance sheets for certain items (%)
 EMI8.1
 
<tb>
<tb> Fe <SEP> Pb <SEP> Ag <SEP> Cu <SEP> Cd <SEP> As <SEP> Sb <SEP> Ge
<tb> Load
<tb>
 
 EMI8.2
 Itrtit nocompEL-
 EMI8.3
 
<tb>
<tb> ant <SEP> the <SEP> residue <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 4.23 <SEP> 29.56 <SEP> 0.03 <SEP> 7.39 <SEP > He, 29
<tb> sidu <SEP> of <SEP> lixiation <SEP> ores <SEP> 100 <SEP> 100 <SEP> 100 <SEP> 95.76 <SEP> 70.41 <SEP> 99.94 <SEP> 92 , 59 <SEP> b8.70
<tb> tower-oellule <SEP> 0 <SEP> 0 <SEP> 0 <SEP> .0 <SEP> 0.03 <SEP> 0.01 <SEP> 0
<tb> Products
<tb> lu <SEP> ci <SEP> on <SEP> subsidiary <SEP> 74.03 <SEP> 0 <SEP> 0 <SEP> 97.54 <SEP> 87.10 <SEP> 82.37 <SEP > 48.19 <SEP> 81.70
<tb>
 
 EMI8.4
 siau! 110Hlb0UX 24.04 100 98.78 6.17 7.21 15, lE 32, .23 28.42
 EMI8.5
 
<tb>
<tb> rte <SEP> or <SEP> bonus <SEP> 1,

  91 <SEP> 0 <SEP> 1.22 <SEP> -3.72 <SEP> 5.69 <SEP> 2.44 <SEP> 19.57 <SEP> -10.12
<tb>
 2nd phase To 175 1 of solution originating from the first phase, 4787 g of raw wheat were added. Stirring was maintained for 4 hours, the temperature varying between 95 and 100 0.



  At the end of the operation, 175 liters of solution were separated and 2202 g of sulphurous residue was collected. The analyzes and reviews of certain elements are shown in Tables 3 and 4.

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 TABLE 3 Analysis of the different products
 EMI9.1
 
<tb>
<tb> CHARGE <SEP> INDUCED <SEP> OBTBRUS
<tb>
 
 EMI9.2
 Solution before Blendes Solut.on after 1? Ôsidu surruduotion.

   flood reduction furious 1, v ############################ - j ############### ## - ## - # quantity 175 liters 4 787 g 175 liters 2 269 Zn total 85.2 g / 1 57.70 95.99 9/1 14., 10
 EMI9.3
 
<tb>
<tb> Zn <SEP> sol.H2O <SEP> 0.8 <SEP>% <SEP> 3.59 <SEP>%
<tb>
 
 EMI9.4
 Total Fe 26.7 g / 1 1.95, 26.73 g / 1
 EMI9.5
 
<tb>
<tb> Fe <SEP> 2+ <SEP> 2.5 <SEP> g / 1 <SEP> 25.73 <SEP> g / 1
<tb> Fe3 + <SEP> 24.2 <SEP> g / 1 <SEP> 1 <SEP> g / 1
<tb> Pb <SEP> 3.10 <SEP>% <SEP> 5.95 <SEP>%
<tb>
 
 EMI9.6
 Cd 0.19gli 0.19 230 mg / 1 O, U3 ;; ,, at le479 / 1 (), 62 1.7; /. 0.57 Ge 3.86 mg / 1 0.002; 8 m; ¯j / 1 0.0Ù7) 1 As 233.4 0.011 240 mi; / 1 0, () 5 Sb 30 0.015;

   41/1 ¯ U, 053 µ1 H2S04 30 g / 1 31 g / 1
TABLE 3 Zinc and iron balance
 EMI9.7
 #. ############# - # -. #
 EMI9.8
 
<tb>
<tb> Change <SEP> Zn <SEP> Fe
<tb>
 
 EMI9.9
 solution 84, 85 97, 66 y raw blende ¯¯2L2¯¯- 2 45 total 100.00 100.00
 EMI9.10
 
<tb>
<tb> Products
<tb> solution <SEP> 95.06 <SEP>% <SEP> 98.15 <SEP>%
<tb> sulphurous <SEP> residue <SEP> 1.81 <SEP>, '<SEP> 1.71 <SEP>%
<tb> loss <SEP> or <SEP> bonus <SEP> 3.13 <SEP>% <SEP> 0.14 <SEP>%
<tb> -----------
<tb>
 
 EMI9.11
 total 100.00; 100.00

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From these tables we can deduce the yields of dissolution of zinc and iron contained in the raw blende: - yield of zinc solution: 88.07% - "" "iron:

   26.80%
The amount of sulfur in the form of sulfide added relative to the stoichiometric amount needed to reduce the ferric iron present in. ferrous iron amounts to: 1.25.



   The reduction efficiency of fornic iron to ferrous iron: 95.88% 3rd phase
To 175 liters of solution from the second phase was added 1 enter, over 4 hours, 13.338 g of roasted blende whose particle size was less than 200 mesh; this operation took place at a temperature of 90 0 and the pH was maintained between 1.7 and 3.



     Then air was blown in an amount equal to 5 times the stoichiometric amount needed to oxidize the iron.



   The solution was then separated from the residue. The analyzes of certain elements of the starting products of the operation and of the products obtained gave results which are shown in Table 5, while Table 6 gives the results.

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     TABLE 5 Analysis of the different products
 EMI11.1
 CHAltGE: FL1YIT; () B1 '': ;;:; Ui 'Solution ------- 31IJndet 301uti; - ;;: ----------- p: r;:; c.Ü!' y i tô before f; 3. '> .... E: F ::: tpr0} dC1 oxidation oxidation, fr -.: L -. ---- ¯ ............... 4> -04 $> ..... ¯-¯. "", It4 175 liters 13 338 f: 175 liters, 10 6 <J2;.; 9 5 1 9 9 ±; / 1 70.62 152.196 3,; / 1 4.62 ,,.



  > t 26.73 r; / 1 2, G2 2; j i 3, U5 i i the i 42
 EMI11.2
 
<tb>
<tb> 25.1 <SEP> g / 1
<tb> i <SEP> g / 1
<tb>
 
 EMI11.3
 2Jb flJ # i / 1 f. (-4- ':' 1 2 C 2 - \ 1 "/ 1 7, .¯: - ,. le7" / 1 () 117 "1" 5 ">; / 1 (," '7 n,: / 1 r "" 9 "1;, 5 1 ';:" / 1, ¯, 3' .. "240 # 7s / i (J '0'. (", '/,>, 1. 2 #>; 1, /. L 1, z T; 41 F.1, / - 0.012 ;. i 1.56, n ./1 i, .- Çi 6.



  241 n "- / lt 75 '; / 1 -¯. -O.¯ .......-. D.¯ .......,.-...... ¯¯ .¯ ..¯.¯ TABLE 6 Balance of certain elements (in%)
Zn Fe Or As Sb Ge Cd
 EMI11.4
 ion 72.88 93.19 94.61 t9, ùE 81.16 69, or E5.1.12 100 e gr. 27.12 6.81 5.34 10.52 z z,>: 431, Ol; 1:, 1>.



  100.00 100.00 100.00 100.00 100.00 1 <j> w, <> i, 100, GO lfi <,, <->> its obtained ion 101.59 10.63 84.93 0, (il 3.13 4.67 100.72 25.2 sity
 EMI11.5
 198F, 89, Ob 22.93 b9.96 115.39 72,, 2 2.71 70.7 or -3.47 +0.29 -7.1 ";, 13 -18.52 2 <3, Ji. - 3.43 4,?. ':' 100.00 1 <J <', 0b 10'., 0! - 10 .., 0 .. l- ;, ',, JJ 1', ". , ', :: io ...'; '.. 1 (; 0.' ',' ..

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 EMI12.1
 



  Two balances are p> irticuliôr.; Nent izatrec: axts to be established; this FJont t on the one hand, the re: 2: m:! ent cte put e; i solution of the sine ooé tzju in the z.eutxv: l., ::: zat which was put in uolutionj we obtain:. zrLi .. !! .. J1ttr! 1.i ..!. :: 2ll! .¯ ': .. J:' Jl du 'p ± .â¯cipi t of 1:81: in du ncutru11slt .L 12 - 1.,. 86, - 03.0 27.12 on the other hand, the loss of copper due to the fact that part of the copper in the solution is precipitated; we obtain :
 EMI12.2
 Cu cont! Ltu ci.nlUJ the nL'úcini té - Cu contained the neutruli '' ': nt Cu starting solution
 EMI12.3
 22.93 - 5.ill 18.54 v. '
94.61
The present invention makes it possible, among other things, to avoid the evolution of dangerous gases such as arsenamine, since, for the reduction, raw blende is used instead of metals.

   It has, on the other hand, been observed that when the reduction is carried out by means of a complex ore of zinc, lead, iron and copper, the sulphides of zinc and copper are used for the reduction. This fact can contribute to the valorization of zinc and copper contained in such a minorai.
 EMI12.4
 



  During 1 plisse ae p ± 6cipittiO] l of iron, one notes' ..U1 \ divination Q0 certain impurities, coin- ,, arsenic, 1 'an ti ... 0¯;' l, g; ;: a14.à., i;. # and fluorine much better than by other known proe-acs.



  It is well .. understood that 11 i!;. VB!: - ;; ::. Oll is not limited to lt t. ':,: E..1I: l 1 ...:, C.': . plus 1 ::. ttt and ('u' 0 :: 1. cu.ty bring divorces: vo:; yw¯ .. tion:.: ¯¯2.2- exit CL 1 "jJor0 '; of the invention G.1.'il: i j.; i 1 st: -.- ... "J ....;.:: ... 't:' \ 4C: 3 ',. t:' 1: .1 ..: te. .'3

 

Claims (1)

EMI13.1 Rjvs:. 'Ricic: & G'l :: =.]; 2: 0 & 1. Proceeds of valuation Ci'. ^, .R: Js ': "-:': 'uc of the leaching of matter.'. Zilicifjre: . such as 1er zé. .ic, and :: 8 l1xiviution of 'grilled blendes' in view of the 'ass?.: r: .t1011 of certain :.' metals and in particular zinc, concintmit to subject '', in turn these leaching pipelines to a subsequent lwztvitioli at atmospheric pressure and at a ta: .. nG,: ttux temperature between 50 0 and the boiling temperature used it. 1.UH: 3 dilute sulfuric acid solution of which 1 '. Co: .ce.ttration of free acid ¯ at the start is between 10U 6/1 and 250,:;, / 1 in quantity equal to 2 to 5 times the amount of stoec :: ioa: w ;; ttc of acid necessary to dissolve the contained zinc 1 .. ::: lodit leach residue, which forms a sludge denominated plum residue comprising é7. :. valorishblec insoluble substances such as lead, silver .t gold, m "; l8.nge è. uini solution to which is then added at a temperature between 50 0 and lu t einp é 1, atur d 'boiling a sulphide ore comprising in particular zinc sulphide in an amount ;;; o.le 8. 1. to 1 Go 1.5 faith ;.' the quantity stoec1: iom6triql1G!: J.E :: l1t necessary w reduction to EMI13.2 the ferrous state, iron present in the ferric state in said solution, a sulphurous residue is separated from said solution EMI13.3 which is oxidized and which precipitates the iron contained therein using OOlù.r.18 oxidizing the oxygen of the air necessary for li, formation of iron oxide, at a temperature between 50 C and li teiJpGrat0u = e of boiling, "adding one neutralized cont.;:. r; t ae zinc oxide such as blende i) r11160 in the desired quantity to maintain 'm pH of 1.7 3 so rj-1c 1 iron by precipitating into it at 'a, tïtre:;, 1,.; Pure; Jtàz tell.c that arsenic, p .J¯' Evl tLÛato ... l ;, le tu '' : .i.?. a? ti ... and the l'luor. <Desc / Clms Page number 14> EMI14.1 2. PruoJd '. according to 1t ..: rE; :: .. u1.8I.4tio.ü 1, characterized :. c'j "lU 1 0 :. uses raw bl.?i.c;,3 for reduction. 3, Process according to r8vedi; ' tion 1, characterized in that in order to reduce the iron in solution, a mixed sulphurous ore of zinc, copper, lead and iron is used, of which the zinc and copper are dissolved. EMI14.2 4. Process according to the previous s r evez.di .: aions, characterized in that it is carried out in at least two distinct phases. EMI14.3 5. Process according to claim 4, because it is carried out in two distinct phases comprising a phase (the dissolving of the sine and reduction of the iron and an iron precipitation phase. 6. The method of claim 4, c a r a c t é - EMI14.4 In this, it is carried out in three phases, namely a phase of dissolving the sine with separation of the plo residue! Jbex, a reduction of iron from the ferric state to the ferrous state by red-uc weur, a nlfaa of neutrF: 2j¯sea: ion of free acid and oxidation and precipitation of iron. 7. Method according to claim 4, characterized in that it e ..> t carried out in four phases;:;, namely a phase of dissolving the zinc, a phase of reducing the iron from the ferric state in the ferrous state by the reducing agent, a neutral phase EMI14.5 lisr..tion of free acid after reduction and a phase of oxidation and precipitation of iron. S. Proceed following the revonaication. ., o a r was o t ized in that it is carried out in three phases, namely a phase of EMI14.6 dissolving the sine and reducing f'Lu iron ¯'vve.c ferric a 1 'é + ;, ferrous, a P: ilJ8 and': neutralization of the free acid and a dlcxyc phase., 4u -ior- et d'j vol> â.t.'cion du fur. <Desc / Clms Page number 15> 9. A process according to either of the preceding claims, characterized in that the iron is oxidized and precipitated from a solution having a density of 1.20 to 1.5, a content iron of 50 9/1 at most, the Fe3 + / Fe 2+ ratio in this solution being less than 0.05, said solution containing more than 300 mg / 1 of copper retort catalyst and in that the. particle size of the neutralizer is less than 200 inesh, 10. Process according to either of the preceding claims, characterized in that the various operations of subsequent leaching, reduction and addition of the neutralizer during the oxidation each have a duration of several hours, preferably between 4 to 6 hours.