CA1061567A - Pyrometallurgical process for lead refining - Google Patents
Pyrometallurgical process for lead refiningInfo
- Publication number
- CA1061567A CA1061567A CA238,839A CA238839A CA1061567A CA 1061567 A CA1061567 A CA 1061567A CA 238839 A CA238839 A CA 238839A CA 1061567 A CA1061567 A CA 1061567A
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- CA
- Canada
- Prior art keywords
- lead
- zinc
- sintering
- furnace
- tailings
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B13/00—Obtaining lead
- C22B13/02—Obtaining lead by dry processes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process is provided for obtaining lead bullion by the reduction of sintered ore which is produced by sintering materials including lead concentrate, said process being characterized in that zinc removed tailings are mixed into said materials, whereby the productivity of the pyrometallurgical lead refining may be improved and valuable metals may also be recovered from the zinc removed tailings.
A process is provided for obtaining lead bullion by the reduction of sintered ore which is produced by sintering materials including lead concentrate, said process being characterized in that zinc removed tailings are mixed into said materials, whereby the productivity of the pyrometallurgical lead refining may be improved and valuable metals may also be recovered from the zinc removed tailings.
Description
s~
BACKGROUND O~ TIIE Il\~VENTION
_____ This invention relates to pyrometallurgical refin-ing of lead wherein lead oxide obtained by sintering lead concentrates, particularly sulfide minerals such as Galena is subjected to reduction refining treatment.
More specifically, this invention relates to a process for enhancing the productivi-ty in -the pyrometallurgical lead refining by mixing Waeltz process tailings or magnetically separated tailings in the zinc refining process to the lead concentrate, and then sintering the - mixtureO ~he process is concurrently capable of - conveniently recovering valuable metals such as gold, silver etc. contained in the zinc removed tails.
` Because of the difficulty in reducing lead sulfide to metallic lead, i-t is a usual me-thod for the pre-treatment to once convert lead concentrate to the form of lead oxide by sin-tering the lead concentrate or by roasting and then sintering it to remove a major portion of sulfur contained thereinO When the sintered ore is to be smelted in a blast furnace, it is also known that the production of a suitable amou~t of slag having a good fluidity is necessaryO ~he lead concentrate, in genera], j has a less content of slag making components available for the production of slag such as iron, silica, etcO due -to i-ts high grade of leadO ~ccordingly, in main-taining the s-table operation of the furnace it is a common practice -to charge slag making agents directly in-to a furnace or to add them to the ore indirectly as, for example, by adding the slag making agents to -the ore -' ', ~
~ ,.; : :.. .
~0~
during the roasting and sintering -treatmen-t~ Such slag making agents include iron scraps or pyrite cinders as iron source and siliceous stone, copper smalting furnace slag, or lead smelting furnace slag as silica source.
When the iron scraps are employed, they are charged into a blast furnace independently of or -together with the sintered ore. When the pyri-te cinders are employed, they are mixed in-to the lead concentrate before its sintering and pyrite cinder containing sintered ores thus obtained are charged into a blast furnaceO
~he aforementioned me-thod, however, have disadvantages ; as follows:
When the iron scraps are charged in-to a blast furnace together with the sintered ore, siliceous stone, coke 9 etc., it is difficult to have the iron scraps uniformly distribute within the furnace because of their non-uni-- form shapes. When the pyrite cinders are employed, the ; problem of the unevenness of the distribution within the furnace can be solved because it is possible to preliminarily mix the pyrite cinders with lead concentrate and sinter them togetherO However, the iron exisitn in the pyrite cinder is in the form of hematite and accord-ingly should be reduced to the ferrous form to raise the gas ratio of C0 to C02 in the furnace gas. Eowever, when the reducing ability of the furnace atmosphere is weakened as the furnace atmosphere fluctuates according to the furnace operating circumstance~ the reduction of hematite often becomes insufficient so that the slag is not produced having a good fluidity~ In such case, the operation of -the furnace becomes unstable and also the lead slag loss namely loss of lead into -t,he slag is increasedO
l'he Waeltz process slag in -the zinc refining process as mentioned hereinbefore refers -to the -tailings left by fuming zinc from the distillation residue from pyrometal-lurgical æinc refining process or -the leaching residue from hydrometallurgical zinc refining process, said fuming of zinc being carried out by mixing such residue with coke and treating the mix-ture in a rotary kiln by the aid of fine coal burningO Such additional treatment is required to recover zinc from the distillation or leaching residue which has still a high content of zincO
Also, in the distillation refining of zinc, when the zinc is sufficiently reduced and fumed off, the co-existen-t iron oxide has been converted in-to elemental ironO
Therefore, -the distillation residue may be separated into a non-magnetic residue portion having a high zinc con-tent and a magnetic residue portion containing iron (hereinafter referred to as magnetically separated tailings). The former, that is, -the high zinc containing residue por-tion is repeatedly treated in the zinc refining process. l'he tailings which are left by removing zinc from the residue discharged in the pyro- or hydro metallurgical zinc refining process, as explained with reference to Wael-tz tailings and magne-tically separated ~tailings hereinabove~
are termed herein "zinc removed tailings" and contains ;
gold, silver and copperO An e~ample of its composition is set forth below in ~able I.
~:: :. ' ,. . . .
Table ]
___ ~ . . ~ ~
contents 2O7g/T 600g/T _ _ ~6/o ¦ 2.~/o 8% 3%
Previously, the zinc removed tailings have been treated mainly by a smelting furnace or conver-ter to recover valuable metals from themO But 9 when they are -treated in the smelting furnace, -th.e reduc-- 10 ing atmosphere in the furnace prevents the iron from sufficien-tly falling into slag and the treatment "~ capacity of -the furnace is inevitably restricted.
- In case the zinc removed tailings are treated in -the converter, an increase in the amount of the zinc removed tailings to be treated results in a ~ proportional decrease in -the amount of matte which : is a primary object -to be treated by the converter~
Accordingly, from the standpoint of productivity, there is a limi-t in on trea-ting the zinc removed tailings in the converter. For -the aforementioned reasons, the conventional treatment processes are both far from being effectiveO
I have discovered that the zinc removed -tail- :
; ings have excellent effec-ts as slag making agent in the lead blast furnace and also as desulfurizing agent and reducing agentO
Based on this discovery, -this invention provides a pyrometalluri.gical lead refining process having a high productivity~ This invention further provides ~. . .
~
. pyrometallurgical lead refining proces~ in which the lea~
fracti.on lost in-to a slag is less, the operation of the furnac.e is s-table and ye-t valuable metals contained in the zinc removed tailings may be effectively recovered.
S DE~AILED DESCRIPTION OF THE ~rE~ O ] ~D ~
~his inven-tion resides in a pyrometallurgical lead refining process comprising mixing lead concentrate with additives such as lime stone, siliceous stone, etcO~
- desulfurizing the mixture in a sintering process, and charging the resultant sintered ore in-to a blast furnace together with coke to produce lead bullion from the lead : concentrate, characterized in tha-t -the zinc removed tailings obtained in the zinc refining process are mixed with said lead concentrate, lime stone, siliceous stone, i.-:
. 15 etc., the mixture is sintered together and the resultant sintered ore mixture is employed as a charge into the ~
blast furnaceO When the sintering is effected after ::
roasting treatment by a fluidized roasting furnace, the zinc removed tailings are mixed into the ore mixture after the roasting and before the sinteringO When the roasting and sin-tering treatments are continuously carried out only in a sintering furnace without the :;
employment o~ a roasting ~urnace, the zinc removed -tail-ings are mixed in-to the ore mix-ture before they are charged lnto the sintering furnaceO
A typical sintering process according to this lnvention comprises mixing into one part of lead concentrate 0015 - 0020 parts of zinc removed tailings, 0004 - 0005 parts of siliceous stone, 0.1 ~ 0015 parts ,5 , ., , ~ ' S~7 of lime s-tone, 2.5 parts of sintered powcler re-turned ~rom the succeeding process and 0.3 - 0O5 par-ts of lead blas-t furnace slag, charging -the mixture pelletized in a pelle-tizer into a sintering fu:rnace to heat and desulfurize the pelletized mixture therein to produce the sintered ore, and sieving the sin-tered ore into grains and powders.
The grains left on the sieve are ch,~rged into the blast furnace with the addition of coke in a proportion of ~
to 9Y0 relative to the grains~ The powders passed through the sieve are returned -to the mixing step preceding the . sintering ~or reuse. ~he siliceous stone and lime stone ; are added for the purpose of adjusting the composition of the slag, although such addition is unnecessary ~hen ~- the zinc removed tailings contain such components~ ~he lead blast furnace slag is employed as a slag making agent and other substitutes may be employedO ~or example, the slag i.n a copper blast furnace or the slag in a copper .~ flash smelting furnace may be employed together with .~ siliceous stone and lime stoneO However, in general A the lead content of lead blast furnace slag is at relatively a high level ranging from 2 to 4~5% and repetitive employment of a portion of the slag produced is effective to minimize the loss of lead entrained into the slag~
' ~ven when zinc removed tailings are mixed in-to the lead 25 concentrate before sin-tering according to this inven-tion9 the operational conditions of the sin-tering process and the blas-t ~urnace process need not be made differen-t from the conventional practice and conditionsO
It is possible to appropria-tely change -the typical - , . : , , ~ - , , ~, .
5~7 composi-tion ratio mentioned above to ob-tain the optimum slag for the operation of a par-ticular lead, b]ast furnace refining practice. ~he amount of zinc removed tailings ~o be used is de-termined by the -tot~l iron balance and the quantity of zinc present in the slag~ If -this desired to obtain a s].ag con-taining 25 to 27% of iron, 24 to 2~/o of silica and 10% of zinc, i-t is preferable that the amount of zinc removed tai,li.ngs should no-t exceed 2G% of the amount of the lead concentra-teO ~he use of more than 20% of zinc removed tailings can posssibly produce iron in -the furnaceO
In the case where pyrite cinder is used as iron source according to the conventional practice~ there is ' so much magnetite produced in the zinc blast furnace slag that repeated use of the pyrite cinder ma~ render the furnace operating conditions unstableD In contras-t, when - zinc removed tailin~s are emplo~ed, only a small amount of magnetite is produced in the slag so as to permit use of the slag.
What is important in the operation of a lead blast furnace is -that the desulfuriza-tion be suffieiently effected during the sintering process. ~he use of zinc removed tailings provides superior effec-ts in this respect ,, as well~ In the case of the conventi.onal formula using pyrite cinder,, there was an average lo 90% Of residual sulfur in the sintered material and a-t over 40% of the occurrences there was more than 2. C/O of residual sulfur conten-tO In con-trast, when zinc removed tailings was used, there was an average l~ 69% of residual sulfur 5 tii~
conten-t and i.-t never occurred that -the sulfur content exceeded 2.~oO ~his is due to the shape and physi.cal characteristics of -the zinc removed tailings serving to provide satisfac-tory draft or ventila-tion during -the sintering process.
'~he zinc removed tailings also produces salient effects in reaction in a blast furnace~ Being present in the metallic and par-ticulate form, -the iron and sili silicon in the zinc removed tailings are not subjected to internal oxidizationO Accordingly, a charge of the zinc removed tnilings into the blast furnace does not provide a large amount of iron oxides to be reduced in the furnace so that the reducing agents may no-t be so excessively consumed for the reduction of the iron oxide as to be in short supply.
~he iron and silicon in their metallic ~orms also function as reducing agent and desulfurizing agent to aid in stabilization of the operating conditions and efficiency of the operation of the furnace~ As a consequence, the amount of lead lost into the slag is decreased and no accretion collects on the blast furnace, resulting in an extension of the con-tinuous running time of the furnace (reduction of the shut down time).
In addi-tion, the present invention provides for effecti~ely recovering values such as gold and silver contained in zinc removed tailingsO Since the lead blast furnace does not h~ve so strong a reducing atmosphere as the copper blast furnace, a considerable amount of -the iron ~n the zinc removed tailings falls into the slag so - 9 - :
'~:
that the existence of the iron se-ts no limit to the capacity of treatmen-tO The gold, silver and copper present in the zinc removed tailings are concentràted in the lead bullion and drossO The dross may be treated in a known mcmner as by an electric furnace to recover the gold, silver and copper. According to -the trea-tment by an electric furnace 9 abou-t 9~/0 of the copper and about 96% of the gold and silver, respectively in the zinc removed tailings may be recovered.
- 10 It is to be appreciated from the foregoing that the `. .present invention provides an improved efficiency in lead ;. blast furnace as well as enabling the recovery of valuable ~ metals in zinc removed tailings by utilizing the zinc ~!~ removed tailings for the lead blast furnace refinery in :
an expedient manner and that it -thus greatly lends itself to the smelting of zinc and leadD
The present invention will now be described with reference to a working exampleO
.; Example - 20 Lead concen-trate, magnetically separated residue, siliceous stone 9 lime stone, lead blast furnace slag and powders returned from the sin-tering process were mixed together at a rate of 128 T/day, 2002 ~'/day, 501 T/day, 16.0 T/day~ 46.2 T/day and 320 T/day, respectively and pelletized in a pelletizer~ The thus pelletized mix-ture was desulfurized and sintered by heating i-t up to 900~
in a sin-tering machineu The sintered ore was sieved through a ~0 mm mesh screen~ The ore passed through the i screen was returned to the mixing step precedi.ng the - 10- ', ,.
sintering process for reuse while the ore left on the screen was charged into a lead blast f`urnace toge-ther with cokes in-troduced at a ra-te of 17 ~/dayO ~he operation of the furnace under -the normal operating conditions produced lead bullion, dross and slag at a : rate of 78.2 T/day, 12~4 ~/day and 10609 T/day, respectively. ~6.2 T/day out of -the sla~ was repea-tedly used as a silica source in the sin-tering process~
The operation was very favourably and smoothly run ` 10 under the foregoing operating condi-tions for two monthsO
~ The residual sulfur content in the sintered ore was : lo 69% on the averageO ~he lead content i.n the lead blas-t furnace slag was 1.66%~ exhibiting a marked decrease as compared to the average 3046% in the case of the `. 15 conventional process using pyrite cinder. ~urthermore, due to the accre~tion on the furnace it has heretofore been inevitably required to shut down the furnace after the opera-tion for one and a half monthsO According to the process of this invention, no accretion was observed ; 20 even after the two mon-ths operation and the furnace did ` not need be shut do~m~ 96~4% of the gold, 96.6% of the silver and 90% of the copper in the zinc removed -tailings were recovered according to this inventionO
.
BACKGROUND O~ TIIE Il\~VENTION
_____ This invention relates to pyrometallurgical refin-ing of lead wherein lead oxide obtained by sintering lead concentrates, particularly sulfide minerals such as Galena is subjected to reduction refining treatment.
More specifically, this invention relates to a process for enhancing the productivi-ty in -the pyrometallurgical lead refining by mixing Waeltz process tailings or magnetically separated tailings in the zinc refining process to the lead concentrate, and then sintering the - mixtureO ~he process is concurrently capable of - conveniently recovering valuable metals such as gold, silver etc. contained in the zinc removed tails.
` Because of the difficulty in reducing lead sulfide to metallic lead, i-t is a usual me-thod for the pre-treatment to once convert lead concentrate to the form of lead oxide by sin-tering the lead concentrate or by roasting and then sintering it to remove a major portion of sulfur contained thereinO When the sintered ore is to be smelted in a blast furnace, it is also known that the production of a suitable amou~t of slag having a good fluidity is necessaryO ~he lead concentrate, in genera], j has a less content of slag making components available for the production of slag such as iron, silica, etcO due -to i-ts high grade of leadO ~ccordingly, in main-taining the s-table operation of the furnace it is a common practice -to charge slag making agents directly in-to a furnace or to add them to the ore indirectly as, for example, by adding the slag making agents to -the ore -' ', ~
~ ,.; : :.. .
~0~
during the roasting and sintering -treatmen-t~ Such slag making agents include iron scraps or pyrite cinders as iron source and siliceous stone, copper smalting furnace slag, or lead smelting furnace slag as silica source.
When the iron scraps are employed, they are charged into a blast furnace independently of or -together with the sintered ore. When the pyri-te cinders are employed, they are mixed in-to the lead concentrate before its sintering and pyrite cinder containing sintered ores thus obtained are charged into a blast furnaceO
~he aforementioned me-thod, however, have disadvantages ; as follows:
When the iron scraps are charged in-to a blast furnace together with the sintered ore, siliceous stone, coke 9 etc., it is difficult to have the iron scraps uniformly distribute within the furnace because of their non-uni-- form shapes. When the pyrite cinders are employed, the ; problem of the unevenness of the distribution within the furnace can be solved because it is possible to preliminarily mix the pyrite cinders with lead concentrate and sinter them togetherO However, the iron exisitn in the pyrite cinder is in the form of hematite and accord-ingly should be reduced to the ferrous form to raise the gas ratio of C0 to C02 in the furnace gas. Eowever, when the reducing ability of the furnace atmosphere is weakened as the furnace atmosphere fluctuates according to the furnace operating circumstance~ the reduction of hematite often becomes insufficient so that the slag is not produced having a good fluidity~ In such case, the operation of -the furnace becomes unstable and also the lead slag loss namely loss of lead into -t,he slag is increasedO
l'he Waeltz process slag in -the zinc refining process as mentioned hereinbefore refers -to the -tailings left by fuming zinc from the distillation residue from pyrometal-lurgical æinc refining process or -the leaching residue from hydrometallurgical zinc refining process, said fuming of zinc being carried out by mixing such residue with coke and treating the mix-ture in a rotary kiln by the aid of fine coal burningO Such additional treatment is required to recover zinc from the distillation or leaching residue which has still a high content of zincO
Also, in the distillation refining of zinc, when the zinc is sufficiently reduced and fumed off, the co-existen-t iron oxide has been converted in-to elemental ironO
Therefore, -the distillation residue may be separated into a non-magnetic residue portion having a high zinc con-tent and a magnetic residue portion containing iron (hereinafter referred to as magnetically separated tailings). The former, that is, -the high zinc containing residue por-tion is repeatedly treated in the zinc refining process. l'he tailings which are left by removing zinc from the residue discharged in the pyro- or hydro metallurgical zinc refining process, as explained with reference to Wael-tz tailings and magne-tically separated ~tailings hereinabove~
are termed herein "zinc removed tailings" and contains ;
gold, silver and copperO An e~ample of its composition is set forth below in ~able I.
~:: :. ' ,. . . .
Table ]
___ ~ . . ~ ~
contents 2O7g/T 600g/T _ _ ~6/o ¦ 2.~/o 8% 3%
Previously, the zinc removed tailings have been treated mainly by a smelting furnace or conver-ter to recover valuable metals from themO But 9 when they are -treated in the smelting furnace, -th.e reduc-- 10 ing atmosphere in the furnace prevents the iron from sufficien-tly falling into slag and the treatment "~ capacity of -the furnace is inevitably restricted.
- In case the zinc removed tailings are treated in -the converter, an increase in the amount of the zinc removed tailings to be treated results in a ~ proportional decrease in -the amount of matte which : is a primary object -to be treated by the converter~
Accordingly, from the standpoint of productivity, there is a limi-t in on trea-ting the zinc removed tailings in the converter. For -the aforementioned reasons, the conventional treatment processes are both far from being effectiveO
I have discovered that the zinc removed -tail- :
; ings have excellent effec-ts as slag making agent in the lead blast furnace and also as desulfurizing agent and reducing agentO
Based on this discovery, -this invention provides a pyrometalluri.gical lead refining process having a high productivity~ This invention further provides ~. . .
~
. pyrometallurgical lead refining proces~ in which the lea~
fracti.on lost in-to a slag is less, the operation of the furnac.e is s-table and ye-t valuable metals contained in the zinc removed tailings may be effectively recovered.
S DE~AILED DESCRIPTION OF THE ~rE~ O ] ~D ~
~his inven-tion resides in a pyrometallurgical lead refining process comprising mixing lead concentrate with additives such as lime stone, siliceous stone, etcO~
- desulfurizing the mixture in a sintering process, and charging the resultant sintered ore in-to a blast furnace together with coke to produce lead bullion from the lead : concentrate, characterized in tha-t -the zinc removed tailings obtained in the zinc refining process are mixed with said lead concentrate, lime stone, siliceous stone, i.-:
. 15 etc., the mixture is sintered together and the resultant sintered ore mixture is employed as a charge into the ~
blast furnaceO When the sintering is effected after ::
roasting treatment by a fluidized roasting furnace, the zinc removed tailings are mixed into the ore mixture after the roasting and before the sinteringO When the roasting and sin-tering treatments are continuously carried out only in a sintering furnace without the :;
employment o~ a roasting ~urnace, the zinc removed -tail-ings are mixed in-to the ore mix-ture before they are charged lnto the sintering furnaceO
A typical sintering process according to this lnvention comprises mixing into one part of lead concentrate 0015 - 0020 parts of zinc removed tailings, 0004 - 0005 parts of siliceous stone, 0.1 ~ 0015 parts ,5 , ., , ~ ' S~7 of lime s-tone, 2.5 parts of sintered powcler re-turned ~rom the succeeding process and 0.3 - 0O5 par-ts of lead blas-t furnace slag, charging -the mixture pelletized in a pelle-tizer into a sintering fu:rnace to heat and desulfurize the pelletized mixture therein to produce the sintered ore, and sieving the sin-tered ore into grains and powders.
The grains left on the sieve are ch,~rged into the blast furnace with the addition of coke in a proportion of ~
to 9Y0 relative to the grains~ The powders passed through the sieve are returned -to the mixing step preceding the . sintering ~or reuse. ~he siliceous stone and lime stone ; are added for the purpose of adjusting the composition of the slag, although such addition is unnecessary ~hen ~- the zinc removed tailings contain such components~ ~he lead blast furnace slag is employed as a slag making agent and other substitutes may be employedO ~or example, the slag i.n a copper blast furnace or the slag in a copper .~ flash smelting furnace may be employed together with .~ siliceous stone and lime stoneO However, in general A the lead content of lead blast furnace slag is at relatively a high level ranging from 2 to 4~5% and repetitive employment of a portion of the slag produced is effective to minimize the loss of lead entrained into the slag~
' ~ven when zinc removed tailings are mixed in-to the lead 25 concentrate before sin-tering according to this inven-tion9 the operational conditions of the sin-tering process and the blas-t ~urnace process need not be made differen-t from the conventional practice and conditionsO
It is possible to appropria-tely change -the typical - , . : , , ~ - , , ~, .
5~7 composi-tion ratio mentioned above to ob-tain the optimum slag for the operation of a par-ticular lead, b]ast furnace refining practice. ~he amount of zinc removed tailings ~o be used is de-termined by the -tot~l iron balance and the quantity of zinc present in the slag~ If -this desired to obtain a s].ag con-taining 25 to 27% of iron, 24 to 2~/o of silica and 10% of zinc, i-t is preferable that the amount of zinc removed tai,li.ngs should no-t exceed 2G% of the amount of the lead concentra-teO ~he use of more than 20% of zinc removed tailings can posssibly produce iron in -the furnaceO
In the case where pyrite cinder is used as iron source according to the conventional practice~ there is ' so much magnetite produced in the zinc blast furnace slag that repeated use of the pyrite cinder ma~ render the furnace operating conditions unstableD In contras-t, when - zinc removed tailin~s are emplo~ed, only a small amount of magnetite is produced in the slag so as to permit use of the slag.
What is important in the operation of a lead blast furnace is -that the desulfuriza-tion be suffieiently effected during the sintering process. ~he use of zinc removed tailings provides superior effec-ts in this respect ,, as well~ In the case of the conventi.onal formula using pyrite cinder,, there was an average lo 90% Of residual sulfur in the sintered material and a-t over 40% of the occurrences there was more than 2. C/O of residual sulfur conten-tO In con-trast, when zinc removed tailings was used, there was an average l~ 69% of residual sulfur 5 tii~
conten-t and i.-t never occurred that -the sulfur content exceeded 2.~oO ~his is due to the shape and physi.cal characteristics of -the zinc removed tailings serving to provide satisfac-tory draft or ventila-tion during -the sintering process.
'~he zinc removed tailings also produces salient effects in reaction in a blast furnace~ Being present in the metallic and par-ticulate form, -the iron and sili silicon in the zinc removed tailings are not subjected to internal oxidizationO Accordingly, a charge of the zinc removed tnilings into the blast furnace does not provide a large amount of iron oxides to be reduced in the furnace so that the reducing agents may no-t be so excessively consumed for the reduction of the iron oxide as to be in short supply.
~he iron and silicon in their metallic ~orms also function as reducing agent and desulfurizing agent to aid in stabilization of the operating conditions and efficiency of the operation of the furnace~ As a consequence, the amount of lead lost into the slag is decreased and no accretion collects on the blast furnace, resulting in an extension of the con-tinuous running time of the furnace (reduction of the shut down time).
In addi-tion, the present invention provides for effecti~ely recovering values such as gold and silver contained in zinc removed tailingsO Since the lead blast furnace does not h~ve so strong a reducing atmosphere as the copper blast furnace, a considerable amount of -the iron ~n the zinc removed tailings falls into the slag so - 9 - :
'~:
that the existence of the iron se-ts no limit to the capacity of treatmen-tO The gold, silver and copper present in the zinc removed tailings are concentràted in the lead bullion and drossO The dross may be treated in a known mcmner as by an electric furnace to recover the gold, silver and copper. According to -the trea-tment by an electric furnace 9 abou-t 9~/0 of the copper and about 96% of the gold and silver, respectively in the zinc removed tailings may be recovered.
- 10 It is to be appreciated from the foregoing that the `. .present invention provides an improved efficiency in lead ;. blast furnace as well as enabling the recovery of valuable ~ metals in zinc removed tailings by utilizing the zinc ~!~ removed tailings for the lead blast furnace refinery in :
an expedient manner and that it -thus greatly lends itself to the smelting of zinc and leadD
The present invention will now be described with reference to a working exampleO
.; Example - 20 Lead concen-trate, magnetically separated residue, siliceous stone 9 lime stone, lead blast furnace slag and powders returned from the sin-tering process were mixed together at a rate of 128 T/day, 2002 ~'/day, 501 T/day, 16.0 T/day~ 46.2 T/day and 320 T/day, respectively and pelletized in a pelletizer~ The thus pelletized mix-ture was desulfurized and sintered by heating i-t up to 900~
in a sin-tering machineu The sintered ore was sieved through a ~0 mm mesh screen~ The ore passed through the i screen was returned to the mixing step precedi.ng the - 10- ', ,.
sintering process for reuse while the ore left on the screen was charged into a lead blast f`urnace toge-ther with cokes in-troduced at a ra-te of 17 ~/dayO ~he operation of the furnace under -the normal operating conditions produced lead bullion, dross and slag at a : rate of 78.2 T/day, 12~4 ~/day and 10609 T/day, respectively. ~6.2 T/day out of -the sla~ was repea-tedly used as a silica source in the sin-tering process~
The operation was very favourably and smoothly run ` 10 under the foregoing operating condi-tions for two monthsO
~ The residual sulfur content in the sintered ore was : lo 69% on the averageO ~he lead content i.n the lead blas-t furnace slag was 1.66%~ exhibiting a marked decrease as compared to the average 3046% in the case of the `. 15 conventional process using pyrite cinder. ~urthermore, due to the accre~tion on the furnace it has heretofore been inevitably required to shut down the furnace after the opera-tion for one and a half monthsO According to the process of this invention, no accretion was observed ; 20 even after the two mon-ths operation and the furnace did ` not need be shut do~m~ 96~4% of the gold, 96.6% of the silver and 90% of the copper in the zinc removed -tailings were recovered according to this inventionO
.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Pyrometallurgical lead refining process for obtaining lead bullion by the reduction of sintered ore which is produced by sintering materials including lead concentrate, characterized in that zinc removed tailings obtained in the zinc refining process are mixed with said materials followed by sintering the mixture, whereby the productivity of the pyrometallurgical lead refining may be improved and valuable metals may also be recovered from the zinc removed tailings.
2. The process of claim 1 wherein the lead concentrate included in said materials is preliminarily subjected to the roasting treatment.
3. The process of Claim 1 wherein in the case where roasting and sintering treatments are continuously carried out in a sintering furnace, said zinc removed tailings are mixed with the materials including the lead concentrate before they are charged into the sintering furnace.
4. The process of Claim 1 wherein said sintering comprises steps of mixing with one part of lead concentrate 0.15 - 0.20 parts of zinc removed tailings 0.04 - 0.05 parts of siliceous stone, 0.1 - 0.15 parts of lime stone, 2.5 parts of sintered powder returned from the succeeding sieving process and 0.3 -0.5 parts of lead blast furnace slag, charging the mixture pelletized in a pelletizer into a sintering furnace to heat and desulfurize the pelletized mixture therein to produce the sintered ore, and then sieving through about 30 mm mesh screen the sintered ore into grains and powders.
5. The process of Claim 4 wherein copper blast furnace slag or copper flash smelting furnace slag is employed instead of the lead blast furnace slag.
6. The process of Claim 1 wherein said zinc removed tailings include gold, silver, copper, iron, zinc, silicon and carbon.
7. The process of Claim 1 wherein the amount of said zinc removed tailings to be used is determined by the total iron balance and the quantity of zinc contained in slag produced m a lead refining furnace.
8. The process of Claim 6 wherein the amount of said zinc removed tailings does not exceed 20% of the amount of the lead concentrate.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12332374A JPS5322925B2 (en) | 1974-10-28 | 1974-10-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1061567A true CA1061567A (en) | 1979-09-04 |
Family
ID=14857700
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA238,839A Expired CA1061567A (en) | 1974-10-28 | 1975-10-30 | Pyrometallurgical process for lead refining |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5322925B2 (en) |
| CA (1) | CA1061567A (en) |
| DE (1) | DE2548030B2 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5129442B2 (en) * | 1971-09-26 | 1976-08-25 |
-
1974
- 1974-10-28 JP JP12332374A patent/JPS5322925B2/ja not_active Expired
-
1975
- 1975-10-27 DE DE19752548030 patent/DE2548030B2/en not_active Ceased
- 1975-10-30 CA CA238,839A patent/CA1061567A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5149120A (en) | 1976-04-28 |
| DE2548030B2 (en) | 1976-12-02 |
| JPS5322925B2 (en) | 1978-07-12 |
| DE2548030A1 (en) | 1976-08-12 |
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