AU2021232689A1 - Method for treating lead slag with rotary hearth furnace - Google Patents
Method for treating lead slag with rotary hearth furnace Download PDFInfo
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- AU2021232689A1 AU2021232689A1 AU2021232689A AU2021232689A AU2021232689A1 AU 2021232689 A1 AU2021232689 A1 AU 2021232689A1 AU 2021232689 A AU2021232689 A AU 2021232689A AU 2021232689 A AU2021232689 A AU 2021232689A AU 2021232689 A1 AU2021232689 A1 AU 2021232689A1
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- Prior art keywords
- lead
- pellets
- slag
- rotary hearth
- hearth furnace
- Prior art date
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Links
- 239000002893 slag Substances 0.000 title claims abstract description 90
- 238000000034 method Methods 0.000 title claims abstract description 36
- 239000008188 pellet Substances 0.000 claims abstract description 161
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 135
- 230000009467 reduction Effects 0.000 claims abstract description 111
- 229910052742 iron Inorganic materials 0.000 claims abstract description 70
- 239000011701 zinc Substances 0.000 claims abstract description 44
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 43
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 41
- 238000005453 pelletization Methods 0.000 claims abstract description 35
- 239000011230 binding agent Substances 0.000 claims abstract description 34
- 239000002245 particle Substances 0.000 claims abstract description 25
- 235000019353 potassium silicate Nutrition 0.000 claims abstract description 20
- 238000000926 separation method Methods 0.000 claims abstract description 20
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical group [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229920000881 Modified starch Polymers 0.000 claims abstract description 19
- 239000004368 Modified starch Substances 0.000 claims abstract description 19
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 19
- 235000019426 modified starch Nutrition 0.000 claims abstract description 19
- 239000000203 mixture Substances 0.000 claims abstract description 17
- 230000008569 process Effects 0.000 claims abstract description 16
- 238000002156 mixing Methods 0.000 claims abstract description 8
- XLOMVQKBTHCTTD-UHFFFAOYSA-N zinc oxide Inorganic materials [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 39
- 238000003723 Smelting Methods 0.000 claims description 29
- 229940056932 lead sulfide Drugs 0.000 claims description 28
- 229910052981 lead sulfide Inorganic materials 0.000 claims description 28
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical group [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 22
- PIJPYDMVFNTHIP-UHFFFAOYSA-L lead sulfate Chemical compound [PbH4+2].[O-]S([O-])(=O)=O PIJPYDMVFNTHIP-UHFFFAOYSA-L 0.000 claims description 15
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 claims description 15
- 230000004907 flux Effects 0.000 claims description 14
- 238000001465 metallisation Methods 0.000 claims description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 11
- 239000000292 calcium oxide Substances 0.000 claims description 11
- 235000012255 calcium oxide Nutrition 0.000 claims description 11
- 239000002699 waste material Substances 0.000 claims description 11
- 238000010891 electric arc Methods 0.000 claims description 10
- 229910052635 ferrosilite Inorganic materials 0.000 claims description 10
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims description 10
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 9
- 239000003245 coal Substances 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 239000001301 oxygen Substances 0.000 claims description 9
- 239000010439 graphite Substances 0.000 claims description 7
- 229910002804 graphite Inorganic materials 0.000 claims description 7
- 239000000446 fuel Substances 0.000 claims description 6
- 239000011133 lead Substances 0.000 abstract description 111
- 239000000428 dust Substances 0.000 abstract description 37
- 229910000464 lead oxide Inorganic materials 0.000 abstract description 23
- 238000006243 chemical reaction Methods 0.000 abstract description 20
- 238000011084 recovery Methods 0.000 abstract description 15
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract 1
- 238000006722 reduction reaction Methods 0.000 description 98
- YEXPOXQUZXUXJW-UHFFFAOYSA-N oxolead Chemical compound [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 21
- 239000011787 zinc oxide Substances 0.000 description 19
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- KEQXNNJHMWSZHK-UHFFFAOYSA-L 1,3,2,4$l^{2}-dioxathiaplumbetane 2,2-dioxide Chemical compound [Pb+2].[O-]S([O-])(=O)=O KEQXNNJHMWSZHK-UHFFFAOYSA-L 0.000 description 10
- 229910052924 anglesite Inorganic materials 0.000 description 10
- 229910052799 carbon Inorganic materials 0.000 description 8
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 7
- 239000003546 flue gas Substances 0.000 description 7
- 150000002739 metals Chemical class 0.000 description 7
- 230000035699 permeability Effects 0.000 description 6
- 239000011148 porous material Substances 0.000 description 6
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 5
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 5
- 229920002472 Starch Polymers 0.000 description 5
- 229910052708 sodium Inorganic materials 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- 235000019698 starch Nutrition 0.000 description 5
- 239000008107 starch Substances 0.000 description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 description 4
- 238000013019 agitation Methods 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 239000002918 waste heat Substances 0.000 description 3
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- 229910052745 lead Inorganic materials 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- -1 ferrous metals Chemical class 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000005556 hormone Substances 0.000 description 1
- 229940088597 hormone Drugs 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- JQJCSZOEVBFDKO-UHFFFAOYSA-N lead zinc Chemical compound [Zn].[Pb] JQJCSZOEVBFDKO-UHFFFAOYSA-N 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 230000003908 liver function Effects 0.000 description 1
- 230000005923 long-lasting effect Effects 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000000643 oven drying Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 230000028327 secretion Effects 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000010944 silver (metal) Substances 0.000 description 1
- 235000019795 sodium metasilicate Nutrition 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
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
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/04—Working-up slag
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/08—Making spongy iron or liquid steel, by direct processes in rotary furnaces
-
- 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/16—Sintering; Agglomerating
- C22B1/216—Sintering; Agglomerating in rotary furnaces
-
- 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
-
- 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
-
- 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/244—Binding; Briquetting ; Granulating with binders organic
-
- 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
- C22B13/025—Recovery from waste materials
-
- 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
- C22B19/00—Obtaining zinc or zinc oxide
- C22B19/20—Obtaining zinc otherwise than by distilling
-
- 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
- C22B19/00—Obtaining zinc or zinc oxide
- C22B19/30—Obtaining zinc or zinc oxide from metallic residues or scraps
-
- 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
- C22B19/00—Obtaining zinc or zinc oxide
- C22B19/34—Obtaining zinc oxide
- C22B19/38—Obtaining zinc oxide in rotary furnaces
-
- 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
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/10—Dry methods smelting of sulfides or formation of mattes by solid carbonaceous reducing agents
-
- 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
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/001—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
Abstract
The invention discloses a method for treating lead slag with a rotary hearth furnace,
which comprises: (1) pelletizing treatment, wherein pellets are prepared by crushing the
lead slag into lead slag particles with particle sizes less than or equal to 0.074 mm,
mixing the crushed lead slag with a reducing agent, a binder and industrial modified
starch according to a ratio of 100: 20-30: 1-3: 2-4, and feeding the well-admixed mixture
into a disc pelletizing machine, wherein the total moisture content of the pellets is
controlled at 9-12% during the pelletizing process, and the binder is water glass; (2)
baking reduction; and (3) slag-iron separation. The method has the advantages of high
treatment capacity, beneficial to environmental protection, high economic effectiveness,
and capable of increasing the iron reaction rate, achieving the respective recovery of iron,
lead and zinc in the lead slag, and realizing high product quality.
3/3
1 /2
flue
first reduction zone
mixer pelletizing fe ding rotar
dis rgin fflue zinc
z ne oxide
second dust
reduction
zone
molten high
iron temperature - lead oxide dust furnace
slag
Fig.1
Description
1 /2
flue
first reduction zone
mixer pelletizing fe ding rotar
dis rgin fflue zinc z ne oxide second dust reduction zone
molten high iron temperature - lead oxide dust furnace
slag
Fig.1
[0001] The invention relates to the technical field of treatment of metallurgical waste residue, in particular to a method for treating lead residue with a rotary hearth furnace.
[0002] In recent decades, China's lead smelting industry has developed rapidly. According to the data from the World Bureau of Metal Statistics (WBMS), China's total lead output reached 4.665 million tons in 2016, accounting for 41.94% of the world's total output. As of November, the lead consumption was 3.9403 million tons, accounting for 40% of the world's total consumption. However, with the rapid development of the lead smelting industry, a lot of waste residues generated in the production process need to be treated. A lead smelting system discharges 0.71 ton of lead slag for every ton of lead produced. This means over 3.3122 million tons of lead slag was discharged in 2016.
[0003] The lead slag generally contains valuable metals such as Pb, Zn, Fe, Ag, In, Sn, Cu and other metals, for recycling . Direct stockpiling of lead slag will not only cause huge waste of resources, but also allow Pb and Zn in the slag to seep into soil and !0 groundwater under the action of rainwater, and due to the poor decomposability, the pollution thus caused thereby is undetectable, long-lasting and irreversible, which is extremely harmful to the ecological environment. The harm of heavy metals to the ecological environment has attracted worldwide attention, and in-depth researches therefor have been conducted by many scholars. The research results show that Pb !5 and Zn are prone to be enriched in organisms via the food chain, thus provide adverse effects with respect to the liver function of organisms and hormone secretion in blood. Therefore, recovery of valuable metals from lead slag not only reduces the harm to the ecological environment, but also realizes the recycle of resources. Half of the 15 pillar staple mineral resources in China are in short supply, and among the existing state-owned mines, 40% of non-ferrous metal mines will confront with the dilemma of resource depletion. As a rare resource, the supply and demand of non-ferrous metals in China are seriously out of balance, and the supply gap is huge. Every year, a large number of non-ferrous metal products are imported to meet the domestic demand. Therefore, the development of a technology for recovery of valuable metals from lead slag is necessary in view of China's current resource situation. Recycling valuable metals from lead slag can not only make the energy consumption and cost of the production process far lower than the conventional smelting process of these metals, but also alleviate the resource pressure in China and the environmental pressure caused by waste discharge. Therefore, it can be seen that the research on separation and recovery of valuable metals in lead slag has important economic value and environmental protection significance.
[0004] The comprehensive utilization of lead slag focuses on the recovery of lead, and the methods thereof mainly include direct reduction, leaching, electrolysis and flotation. The invention provides a method for treating lead slag with a rotary hearth furnace or at least provides the public or industry with a useful choice.
[0005] It is acknowledged that the terms "comprise", "comprises" and "comprising" !0 may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, these terms are intended to have an inclusive meaning - i.e., they will be taken to mean an inclusion of the listed components which the use directly references, and possibly also of other non-specified components or elements. !5 [0006] Reference to any document in this specification does not constitute an admission that it is prior art, validly combinable with other documents or that it forms part of the common general knowledge.
[0007] According to one example embodiment there is provided a method for treating lead slag with a rotary hearth furnace comprises the following steps:
[0008] (1) pelletizing treatment, wherein pellets are prepared by crushing the lead slag into lead slag particles with particle sizes less than or equal to 0.074 mm, mixing the crushed lead slag with a reducing agent, a binder and industrial modified starch according to a ratio of 100: 20-30: 1-3: 2-4, and feeding the well-admixed mixture into a disc pelletizing machine, wherein the total moisture content of the pellets is controlled at 9-12% during the pelletizing process, and the binder is water glass (i.e. Na2SiO3); the binder and the industrial modified starch can ensure the strength of green pellets; the starch binder in the pellets is decomposed and volatilized under the high-temperature reduction condition of the rotary hearth furnace, and the water glass is not decomposed, which can ensure that the pellets do not pulverize inside the rotary hearth furnace; meanwhile, sodium in the water glass contributes to the reduction of ferric silicate; micro-pores are formed in the pellets as prepared in this way, thus providing a channel for zinc volatilization and increasing the air permeability of the pellets; and CO can enter the pellets to improve the kinetic conditions of chemical reaction and increase the iron reaction rate;
[0009] (2) baking reduction, wherein the pellets are added into the rotary hearth !0 furnace through a vibrating distributor, wherein a first reduction zone of the rotary hearth furnace is a zone where lead sulfate is reduced to lead sulfide and moisture in the pellets is oven-dried, with the settings thereof that the temperature is 550-6000 C and the reduction time of the first reduction zone is 25-30 min, and a second reduction zone is a reduction zone of ZnO, FeSiO3, Fe304 and Fe2O3, with the settings thereof that the !5 temperature is 1230-1280C and the reduction time of the second reduction zone is 20-25 min;
[0010] the pellets react as follows in the first reduction zone:
[0011] PbSO4+4CO=PbS+4CO2
[0012] PbSO4+4C=PbS+4CO;
[0013] lead sulfate is reduced to PbS by C and CO with a conversion rate of 90-95%, while the moisture in the pellets in the first reduction zone is volatilized completely, and the remaining moisture content in the pellets is below 0.5%;
[0014] the temperature of the second reduction zone is set to be above the boiling point of zinc (907 0C); in this zone, zinc oxide in the pellets is reduced to metallic zinc, which volatilizes into flue gas and is collected by a bag dust collector after passing through a waste heat boiler to yield zinc oxide dust with a zinc content of 76.5-78.4% and the volatilization rate of zinc is 94-97%; meanwhile, FeSiO3, Fe304 and Fe2O3 in the pellets are reduced to metallic iron, the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron is more than 80%; and
[0015] 3) slag-iron separation, wherein the total time for the rotary hearth furnace to
rotate one round is 50-60 min; the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron is greater than 80%; the metallized pellets are transferred to a high-temperature furnace, under the condition that the temperature of the high-temperature furnace is set at 1550-1600C, the smelting time is 1-2 h;, a flux is added to adjust the quaternary alkalinity of the metallized pellets to 0.8-1 during high-temperature smelting; and lead metal and iron metal after separation are obtained when the metallized pellets have been smelted in the high-temperature !0 furnace.
[0016] In an alternative embodiment, in step (3), the high-temperature furnace is an electric arc furnace with graphite electrodes.
[0017] Slag-iron separation is ensured. Due to the discharge process of electrode of the electric arc furnace, agitation is formed in a hearth and slag liquid thus tumbles up !5 and down, and lead sulfide in the pellets is burnt into lead oxide at a boundary of a molten pool; meanwhile, under the high-temperature condition, residual carbon in the metallized pellets can also reduce lead sulfide to produce metallic lead; lead oxide and metallic lead are volatilized into flue gas at high temperature and are collected in the form of lead oxide dust by a high-temperature furnace dust collector, the volatilization rate of lead in the metallized pellets is 95-98.5%, and the lead content in the lead oxide dust is 85-88.1%;
[0018] and the metallized pellets are smelted in the high-temperature furnace to yield molten iron with an iron grade greater than 94.8% and the recovery rate of iron greater than 92%.
[0019] In an alternative embodiment, the ratio of the lead slag to the reducing agent to the binder to the industrial modified starch in step (1) is 100: 23-27: 1-3: 2-4.
[0020] In an alternative embodiment, in step (1), the mixture is fed into the disc pelletizing machine and formulated as pellets with particle sizes of 8-12 mm, wherein the falling strength of the pellets is more than 8 times.
[0021] In an alternative embodiment, in step (2), a strong reducing atmosphere in the first reduction zone and the second reduction zone of the rotary hearth furnace can be ensured by controlling an air-fuel ratio of a burner, wherein the concentration of CO is 7-14%, and the concentration of oxygen is 0.8-1.7%.
[0022] In an alternative embodiment, in step (3), the flux is quicklime.
[0023] In an alternative embodiment, the lead slag is waste lead slag produced during lead smelting in a blast furnace, and the lead slag contains 27-35% of TFe, 1.3-3.8% of lead and 2.4-6.2% of zinc.
[0024] In an alternative embodiment, the reducing agent is coal.
[0025] According to the above solution, the method for treating the lead slag with the c0 rotary hearth furnace comprises the following steps: (1) pelletizing treatment, wherein pellets are prepared by crushing the lead slag into lead slag particles with particle sizes less than or equal to 0.074 mm, mixing the crushed lead slag with a reducing agent, a binder and industrial modified starch according to a ratio of 100: 20-30: 1-3: 2-4, and feeding the well-admixed mixture into a disc pelletizing machine, wherein the total moisture content of the pellets is controlled at 9-12% during the pelletizing process, and the binder is water glass; (2) baking reduction, wherein the pellets are added into the rotary hearth furnace through a vibrating distributor, wherein a first reduction zone of the rotary hearth furnace is a zone where lead sulfate is reduced to lead sulfide and moisture in the pellets is oven-dried, with the settings thereof that the temperature is 550-600 0C and the reduction time of the first reduction zone is 25-30 min, and a second reduction zone is a reduction zone of ZnO, FeSiO3, Fe304 and Fe2O3, with the settings thereof that the temperature is 1230-1280 0C and the reduction time of the second reduction zone is 20-25 min; and (3) slag-iron separation, wherein the total time for the rotary hearth furnace to rotate one round is 50-60 min; the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron being greater than 80%; the metallized pellets are transferred to a high-temperature furnace, under the condition that the temperature of the high-temperature furnace is set at 1550-1600 0C, the smelting time is 1-2 h; a flux is added to adjust the quaternary alkalinity of the metallized pellets to 0.8-1 during high-temperature smelting; and lead metal and iron metal after separation are obtained when the metallized pellets have been smelted in the high-temperature furnace.
[0026] The invention provides that:
[0027] (1) The rotary hearth furnace and the electric furnace are used to treat lead-containing slag, which provides a higher treatment capacity and good environmental protection effect.
[0028] (2) Lead sulfate is converted into lead sulfide, so that lead-free pure zinc oxide dust and zinc-free pure lead oxide dust can be obtained separately, which avoids the difficulty of other processes wherein subsequent separation of lead-zinc mixed dust c0 thus obtained is necessary and has higher economic effectiveness.
[0029] (3) Zinc oxide dust and lead oxide dust of higher quality can be obtained by the invention, wherein the volatilization rate of zinc is 94-97%, the zinc content in zinc oxide dust is 76.5-78.4%, the volatilization rate of lead in the metallized pellets is 95-98.5%, and the lead content in lead oxide dust is 85-88.1%. !5 [0030] (4) The strength of the produced pellets, ensures that the pellets are not pulverized in the reduction process, can promote the reduction of iron, and saves the cost caused by adding a large amount of additives like limestone and quicklime to promote the reduction in other processes. Meanwhile, in the volatilization process, the pores are formed in the pellets, providing a channel for zinc volatilization and increasing the air permeability of the pellets; and CO can enter the pellets to reduce iron oxides, so as to improve the kinetic conditions of chemical reaction and increase the iron reaction rate.
[0031] (5) When compared with the existing technology for treating lead slag, this technology omits pellet oven-drying equipment following a molding process and shortens the flow chart accordingly, the respective recovery of iron, lead and zinc in lead slag can be accomplished with only one production line at the same time with good product quality.
[0032] (6) Residual carbon in the metallized pellets can also reduce lead sulfide to provide metallic lead, and lead oxide and metallic lead are volatilized into flue gas at high temperature and are collected in the form of lead oxide dust by a high-temperature furnace dust collector.
[0033] (7) The waste slag treatment and recovery time is shortened and the recovery efficiency is improved.
[0034] In order to more clearly explain the examples of the present invention or the technical solution of the prior art, the drawings necessary for the examples will be briefly illustrated as follows. Obviously, the drawings in the following description are merely some examples of the present invention. For those skilled in the art, other drawings can be obtained according to these drawings without any creative efforts. !0 [0035] Fig. 1 is a frame diagram of instruments used in the invention; and
[0036] Fig. 2 is a flowchart of a method of the invention.
[0037] In order to overcome the above shortcomings, the invention provides a method for treating lead slag with a rotary hearth furnace and a preparation method to solve the !5 problems in the above prior art or at least provides the public or industry with a useful choice.
[0038] A method for treating lead slag with a rotary hearth furnace comprises the following steps:
[0039] (1) pelletizing treatment, wherein pellets are prepared by crushing the lead slag into lead slag particles with particle sizes less than or equal to 0.074 mm, mixing the crushed lead slag with a reducing agent, a binder and industrial modified starch according to a ratio of 100: 20-30: 1-3: 2-4, and feeding the well-admixed mixture into a disc pelletizing machine, wherein the total moisture content of the pellets is controlled at 9-12% during the pelletizing process, and the binder is water glass; the binder and the industrial modified starch can ensure the strength of green pellets; the starch binder in the pellets is decomposed and volatilized under the high-temperature reduction condition of the rotary hearth furnace, and the water glass is not decomposed, which can ensure that the pellets do not pulverize inside the rotary hearth furnace; meanwhile, sodium element in the water glass contributes to the reduction of ferric silicate; micro-pores are formed in the pellets prepared in this way, providing a channel for zinc volatilization and increasing the air permeability of the pellets; and CO can enter the pellets to improve the kinetic conditions of chemical reaction and increase the iron reaction rate;
[0040] (2) baking reduction, wherein the pellets are added into the rotary hearth furnace through a vibrating distributor, wherein a first reduction zone of the rotary hearth c0 furnace is a zone where lead sulfate is reduced to lead sulfide and moisture in the pellets is oven-dried, with the settings thereof that the temperature is 550-6000 C and the reduction time of the first reduction zone is 25-30 min, and a second reduction zone is a reduction zone of ZnO, FeSiO3, Fe304 and Fe2O3, with the settings thereof that the temperature is 1230-1280C and the reduction time of the second reduction zone is !5 20-25 min;
[0041] the pellets react as follows in the first reduction zone:
[0042] PbSO4+4CO=PbS+4CO2
[0043] PbSO4+4C=PbS+4CO;
[0044] lead sulfate is reduced to PbS by C and CO with a conversion rate of 90-95%, while the moisture in the pellets in the first reduction zone is volatilized sufficiently, and the remaining moisture content in the pellets is below 0.5%;
[0045] the temperature of the second reduction zone is set to be above the boiling point of zinc (907°C); in this zone, zinc oxide in the pellets is reduced to metallic zinc, which volatilizes into flue gas and is collected by a bag dust collector after passing through a waste heat boiler to provide zinc oxide dust with a zinc content of 76.5-78.4%, and the volatilization rate of zinc is 94-97%; meanwhile, FeSiO3, Fe304 and Fe2O3 in the pellets are reduced to metallic iron, the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron is more than 80%; and
[0046] (3) slag-iron separation, wherein the total time for the rotary hearth furnace to rotate one round is 50-60 min; the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron is more than 80%; the metallized pellets are transferred to a high-temperature furnace, under the condition that the temperature of the high-temperature furnace is set at 1550-1600 0C, the smelting time is 1-2 h, and a flux is added to adjust the quaternary alkalinity of the metallized pellets to 0.8-1 during high-temperature smelting; , lead metal and iron metal after separation are obtained when the metallized pellets have been smelted in the high-temperature furnace.
[0047] In step (3), the high-temperature furnace is an electric arc furnace with c0 graphite electrodes.
[0048] Slag-iron separation is ensured. Due to the electrode discharge process of the electric arc furnace, agitation is formed in a hearth, slag liquid tumbles up and down, and lead sulfide in the pellets is burnt into lead oxide at a boundary of a molten pool. Meanwhile, under the high-temperature condition, residual carbon in the metallized pellets can also reduce lead sulfide to produce metallic lead; lead oxide and metallic lead are volatilized into flue gas at high temperature and are collected in the form of lead oxide dust by a high-temperature furnace dust collector, the volatilization rate of lead in the metallized pellets is 95-98.5%, and the content of lead in the lead oxide dust is 85-88.1%;
[0049] and the metallized pellets are smelted in the high-temperature furnace to provide molten iron with an iron grade greater than 94.8% and the recovery rate of iron greater than 92%.
[0050] The ratio of the lead slag to the reducing agent to the binder to the industrial modified starch in step (1) is 100: 23-27: 1-3: 2-4.
[0051] In step (1), the mixture is fed into the disc pelletizing machine to prepare pellets with particle sizes of 8-12 mm, and the falling strength of the pellets is more than 8 times.
[0052] In step (2), it ensures a strong reducing atmosphere in the first reduction zone and the second reduction zone of the rotary hearth furnace by controlling an air-fuel ratio of a burner, wherein the concentration of CO is 7-14%, and the concentration of oxygen is 0.8-1.7%.
[0053] In step (3), the flux is quicklime.
[0054] The lead slag is waste lead slag produced during lead smelting in a blast furnace, and the lead slag contains 27-35% of TFe, 1.3-3.8% of lead and 2.4-6.2% of zinc.
[0055] The reducing agent is coal.
[0056] In order to make the technical means, creative features, goals and effects of the invention to be more apparent, the invention will be further demonstrated with specific examples. c0 [0057] Example 1
[0058] (1) Pelletizing treatment, wherein pellets are prepared by crushing the lead slag into lead slag particles with particle sizes less than or equal to 0.074 mm, mixing the crushed lead slag with a reducing agent, a binder and industrial modified starch according to a ratio of 100: 20: 1: 2, and feeding the well-admixed mixture into a disc pelletizing machine, wherein the total moisture content of the pellets is controlled at 9% during the pelletizing process, and the binder is water glass; the binder and the industrial modified starch can guarantee the strength of green pellets; the starch binder in the pellets is decomposed and volatilized under the high-temperature reduction condition of the rotary hearth furnace, and the water glass is not decomposed, which can ensure that the pellets do not pulverize inside the rotary hearth furnace; meanwhile, sodium in the water glass contributes to the reduction of ferric silicate; micro-pores are formed in the pellets as prepared in this way, thus providing a channel for zinc volatilization and increasing the air permeability of the pellets; and CO can enter the pellets to improve the kinetic conditions of chemical reaction and increase the iron reaction rate;
[0059] (2) baking reduction, wherein the pellets are added into the rotary hearth furnace through a vibrating distributor, wherein a first reduction zone of the rotary hearth furnace is a zone where lead sulfate is reduced to lead sulfide and moisture in the pellets is oven-dried, with the settings thereof that the temperature is 5500 C and the reduction time of the first reduction zone is 25 min, and a second reduction zone is a reduction zone of ZnO, FeSiO3, Fe304 and Fe2O3,with the settings thereof that the temperature is 1230 0C and the reduction time of the second reduction zone is 20 min;
[0060] the pellets react as follows in the first reduction zone:
[0061] PbSO4+4CO=PbS+4CO2
[0062] PbSO4+4C=PbS+4CO;
[0063] lead sulfate is reduced to PbS by C and CO with a conversion rate of 90-95%;
[0064] (3) slag-iron separation, wherein the total time for the rotary hearth furnace to rotate one round is 50 min; the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the c0 metallization rate of iron is more than 80%; the metallized pellets are transferred to a high-temperature furnace, under the condition that the temperature of the high-temperature furnace is set at 1550C, the smelting time is 1 h, and a flux is added to adjust the quaternary alkalinity of the metallized pellets to 0.8-1 during high-temperature smelting; lead metal and iron metal after separation are obtained when the metallized pellets have been smelted in the high-temperature furnace.
[0065] In step (3), the high-temperature furnace is an electric arc furnace with graphite electrodes.
[0066] In step (1), the mixture is fed into the disc pelletizing machine to prepare pellets with particle sizes of 8-12 mm, and the falling strength of the pellets is more than 8 times.
[0067] In step (2), it ensures a strong reducing atmosphere in the first reduction zone and the second reduction zone of the rotary hearth furnace by controlling an air-fuel ratio of a burner, wherein the concentration of CO is 7%, and the concentration of oxygen is 0.8%.
[0068] In step (3), the flux is quicklime.
[0069] The lead slag is waste lead slag produced during lead smelting in a blast furnace, and the lead slag contains 27-35% of TFe, 1.3-3.8% of lead and 2.4-6.2% of zinc.
[0070] The reducing agent is coal.
[0071] Example 2
[0072] (1) Pelletizing treatment, wherein pellets are prepared by crushing the lead slag into lead slag particles with particle sizes less than or equal to 0.074 mm, mixing the crushed lead slag with a reducing agent, a binder and industrial modified starch according to a ratio of 100: 30: 3: 4, and feeding the well-admixed mixture into a disc pelletizing machine, wherein the total moisture content of the pellets is controlled at 12% during the pelletizing process, and the binder is water glass; the binder and the industrial modified starch can guarantee the strength of green pellets; the starch binder in the pellets is decomposed and volatilized under the high-temperature reduction condition of the rotary hearth furnace, and the water glass is not decomposed, which can ensure that the pellets do not pulverize inside the rotary hearth furnace; meanwhile, sodium in the water glass contributes to the reduction of ferric silicate; micro-pores are formed in the pellets as prepared in this way, thus providing a channel for zinc volatilization and increasing the air permeability of the pellets; and CO can enter the pellets to improve the kinetic conditions of chemical reaction and increase the iron reaction rate;
[0073] (2) baking reduction, wherein the pellets are added into the rotary hearth furnace through a vibrating distributor, wherein a first reduction zone of the rotary hearth furnace is a zone where lead sulfate is reduced to lead sulfide and moisture in the pellets is oven-dried, with the settings thereof that the temperature is 6000 C and the reduction time of the first reduction zone is 30min, and a second reduction zone is a reduction zone of ZnO, FeSiO3, Fe304 and Fe2O3, with the settings thereof that the temperature is set at 12800 C and the reduction time of the second reduction zone is 25min;
[0074] the pellets react as follows in the first reduction zone:
[0075] PbSO4+4CO=PbS+4CO2
[0076] PbSO4+4C=PbS+4CO;
[0077] (3) slag-iron separation, wherein the total time for the rotary hearth furnace to rotate one round is 60 min; the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron is more than 80%; the metallized pellets are transferred to a high-temperature furnace, under the condition that the temperature of the high-temperature furnace is set at 1600 0C, the smelting time is 2 h, and a flux is added to adjust the quaternary alkalinity of the metallized pellets to 1 during high-temperature smelting; , lead metal and iron metal after separation are obtained when the metallized pellets have been smelted in the high-temperature furnace.
[0078] In step (3), the high-temperature furnace is an electric arc furnace with graphite electrodes.
[0079] In step (1), the mixture is fed into the disc pelletizing machine to prepare pellets with particle sizes of 12 mm, and the falling strength of the pellets is more than 8 times. c0 [0080] In step (2), it ensures a strong reducing atmosphere in the first reduction zone and the second reduction zone of the rotary hearth furnace by controlling an air-fuel ratio of a burner, wherein the concentration of CO is 14% and the concentration of oxygen is 1.7%.
[0081] In step (3), the flux is quicklime.
[0082] The lead slag is waste lead slag produced during lead smelting in a blast furnace, and the lead slag contains 27-35% of TFe, 1.3-3.8% of lead and 2.4-6.2% of zinc.
[0083] The reducing agent is coal.
[0084] Example 3
[0085] (1) Pelletizing treatment, wherein pellets are prepared by crushing the lead slag into lead slag particles with particle sizes less than or equal to 0.074 mm, mixing the crushed lead slag with a reducing agent, a binder and industrial modified starch according to a ratio of 100: 24: 2: 3, and feeding the well-admixed mixture into a disc pelletizing machine, wherein the total moisture content of the pellets is controlled at 10% during the pelletizing process, and the binder is water glass; the binder and the industrial modified starch can guarantee the strength of green pellets; the starch binder in the pellets is decomposed and volatilized under the high-temperature reduction condition of the rotary hearth furnace, and the water glass is not decomposed, which can ensure that the pellets do not pulverize inside the rotary hearth furnace; meanwhile, sodium in the water glass contributes to the reduction of ferric silicate; micro-pores are formed in the pellets as prepared in this way, thus providing a channel for zinc volatilization and increasing the air permeability of the pellets; and CO can enter the pellets to improve the kinetic conditions of chemical reaction and increase the iron reaction rate;
[0086] (2) baking reduction, wherein the pellets are added into the rotary hearth furnace through a vibrating distributor, wherein a first reduction zone of the rotary hearth furnace is a zone where lead sulfate is reduced to lead sulfide and moisture in the pellets is oven-dried, with the settings thereof that the temperature is 5700 C and the reduction time of the first reduction zone is 28 min, and a second reduction zone is a c0 reduction zone of ZnO, FeSiO3, Fe304 and Fe2O3, with the settings thereof that the temperature is 1250 0C and the reduction time of the second reduction zone is 23 min;
[0087] the pellets react as follows in the first reduction zone:
[0088] PbSO4+4CO=PbS+4CO2
[0089] PbSO4+4C=PbS+4CO;
[0090] (3) slag-iron separation, wherein the total time for the rotary hearth furnace to rotate one round is 55 min; the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron is more than 80%; the metallized pellets are transferred to a high-temperature furnace, under the condition that the temperature of the high-temperature furnace is set at 1580C, the smelting time is 1.5 h, and a flux is added to adjust the quaternary alkalinity of the metallized pellets to 0.9 during high-temperature smelting; lead metal and iron metal after separation are obtained when the metallized pellets are smelted in the high-temperature furnace.
[0091] In step (3), the high-temperature furnace is an electric arc furnace with graphite electrodes.
[0092] In step (1), the mixture is fed into the disc pelletizing machine to prepare pellets with particle sizes of 10mm, and the falling strength of the pellets is more than 8 times.
[0093] In step (2), it ensures a strong reducing atmosphere in the first reduction zone and the second reduction zone of the rotary hearth furnace by controlling an air-fuel ratio of a burner, wherein the concentration of CO is 10%, and the concentration of oxygen is 1.2%.
[0094] In step (3), the flux is quicklime.
[0095] The lead slag is waste lead slag produced during lead smelting in a blast furnace, and the lead slag contains 27-35% of TFe, 1.3-3.8% of lead and 2.4-6.2% of zinc.
[0096] The reducing agent is coal.
[0097] Example 4
[0098] The lead slag contains 27% of TFe, 1.5% of lead and 2.5% of zinc; the lead slag is crushed and ground to below 0.074 mm; the lead slag is mixed with the reducing CO agent i.e. coal, a binder and industrial modified starch according to the ratio of 100: 23: 1.5: 2; the mixture is fed into a disc pelletizing machine to prepare pellets with particle sizes of 8-12 mm, and the total moisture content in the pellets is controlled at 9.8%.; the temperature of a first reduction zone of the rotary hearth furnace is set at 5600 C, the reduction time of the pellets is set at 25 min, the temperature of a second reduction zone is set at 12400 C, the reduction time is set at 20 min, the CO concentration in the first and second reduction zones of the rotary hearth furnace is 8%, and the oxygen concentration is 1%; the total time for the rotary hearth furnace to rotate one round is 50 min; after the pellets are reduced in the rotary hearth furnace, lead sulfate is converted into lead sulfide with a conversion rate of 91.5%, the volatilization rate of zinc of 94.77%, zinc oxide dust with a zinc content of 76.8% can be obtained, and the metallization rate of iron is 81.4%; the metallized pellets are hot-loaded into a high-temperature furnace, the temperature of the high-temperature furnace is set at 1550C, the quaternary alkalinity is adjusted to 0.8 by adding quicklime, and the smelting time is 1.2 h; the volatilization rate of lead in the metallized pellets is 95.68%, and the lead content in lead oxide dust is 85.26%; and finally, molten iron with an iron grade of 94.8% is obtained, and the recovery rate of iron is 92.73%.
[0099] Example 5
[00100] The lead slag contains 30% of TFe, 2.8% of lead and 6.2% of zinc; the lead slag is crushed and ground to below 0.074 mm; the lead slag is mixed with the reducing agent i.e. coal, a binder and industrial modified starch according to the ratio of 100: 25: 2: 3, and the binder is water glass; the mixture is fed into a disc pelletizing machine to prepare pellets with particle sizes of 8-12 mm, and the total moisture content in the pellets is controlled at 10.7%.; the temperature of a first reduction zone of the rotary hearth furnace is set at 580 0C, the reduction time of the pellets is 27 min, the temperature of a second reduction zone is set at 12600 C, the reduction time is set at 23 min, the CO concentration in the first and second reduction zones of the rotary hearth furnace is 11%, and the oxygen concentration thereof is 1.3%; the total time for the rotary hearth furnace to rotate one round is 55 min; after the pellets are reduced in the rotary hearth furnace, lead sulfate is converted into lead sulfide with a conversion rate of c0 92.88%, the volatilization rate of zinc of 95.46%, zinc oxide dust with a zinc content of 77.51% can be obtained, and the metallization rate of iron is 83.15%; the metallized pellets are hot-loaded into a high-temperature furnace, the temperature of the high-temperature furnace is set at 1580 0 C, the quaternary alkalinity is adjusted to 0.9 by adding quicklime, and the smelting time is 1.6 h; the volatilization rate of lead in the metallized pellets is 96.94%, and the lead content in lead oxide dust is 87.13%; and finally, molten iron with an iron grade of 95.29% is obtained, and the recovery rate of iron is 93.66%.
[00101] Example 6
[00102] The lead slag contains 35% of TFe, 3.8% of lead and 3.9% of zinc; the lead slag is crushed and ground to below 0.074 mm; the lead slag is mixed with the reducing agent i.e. coal, a binder and industrial modified starch according to the ratio of 100: 27: 3: 4, and the binder is water glass; the mixture is fed into a disc pelletizing machine to make pellets with particle sizes of 8-12 mm, and the total moisture content in the pellets is controlled at 11.9%.; the temperature of a first reduction zone of the rotary hearth furnace is set at 6000 C and the reduction time of the pellets is 30 min, the temperature of a second reduction zone is set at 12800 C and the reduction time is set at 25 min, the CO concentration in the first and second reduction zones of the rotary hearth furnace is 13.5%, and the oxygen concentration thereof is 1.6%; the total time for the rotary hearth furnace to rotate one round is 60 min; after the pellets are reduced in the rotary hearth furnace, lead sulfate is converted into lead sulfide with a conversion rate of 94.27%, the volatilization rate of zinc of 96.69%, zinc oxide dust with a zinc content of 78.4% can be obtained, and the metallization rate of iron is 85.45%; the metallized pellets are hot-loaded into a high-temperature furnace, the temperature of the high-temperature furnace is set at 16000 C, the quaternary alkalinity is adjusted to 1 by adding quicklime, and the smelting time is 2 h; the volatilization rate of lead in the metallized pellets is 97.36%, and the lead content in lead oxide dust is 88.09%; and finally, molten iron with an iron grade of 95.98% is obtained, and the recovery rate of iron is 93.83%.
[00103] Data from the above Examples 1 to 6 were collected and listed in the following table: c0 [00104]
Example 1 Example 2 Example 3 Example 4 Example 5 Example 6
Conversio 90.23 93.88 94.99 91.5 92.88 94.27
n rate of
lead
sulfate to
lead
sulfide %
Volatilizati 94.25 95.76 97 94.77 95.46 96.69
on rate of
zinc %
Zinc 76.58 77.83 78.22 76.8 77.51 78.4
content of
zinc oxide
dust %
Metallizati 82.1 83.62 87.88 81.4 83.15 85.45
on rate of
iron %
Volatilizati 95.89 96.32 98.42 95.68 96.94 97.36
on rate of
lead in
metallized
pellets %
Lead 86.21 87.93 87.62 85.26 87.13 88.09
content in
lead oxide
dust %
Iron 94.98 95.87 96.13 94.8 95.29 95.98
grade %
Recovery 92.34 93.47 94.21 92.73 93.66 93.83
rate ofiron
Emission 0.15 0.14 0.13 0.14 0.15 0.13
of dust
(t/a)
[00105] Lead sulfate is reduced to PbS by C and CO with a conversion rate of 90-95%; meanwhile, the moisture in the pellets in this zone is volatilized sufficiently, and the remaining moisture content in the pellets is below 0.5%;
[00106] the temperature of the second reduction zone is set to be above the boiling point of zinc (907 0C); in this zone, zinc oxide in the pellets is reduced to metallic zinc, which volatilizes into flue gas and is collected by a bag dust collector after passing through a waste heat boiler to provide zinc oxide dust with a zinc content of 76.5-78.4%, and the volatilization rate of zinc is 94-97%; meanwhile, FeSiO3, Fe304 and Fe2O3 in the pellets are reduced to metallic iron, the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron is more than 80%;
[00107] the total time for the rotary hearth furnace to rotate one round is 50-60 min;
[00108] the metallized pellets are hot-loaded into a high-temperature furnace which is an electric arc furnace with graphite electrodes, the temperature of the high-temperature furnace is set at 1550-1600 0C, the smelting time is 1-2 h, quicklime is added as a flux during high-temperature smelting, and the quaternary alkalinity in the pellets is adjusted to be 0.8-1 to ensure slag-iron separation; due to the electrode discharge process of the electric arc furnace, agitation is formed in a hearth, slag liquid tumbles up and down, and lead sulfide in the pellets is burnt into lead oxide at a boundary of a molten pool; meanwhile, under the high-temperature condition, residual carbon in the metallized pellets can also reduce lead sulfide to produce metallic lead; lead oxide and metallic lead are volatilized into flue gas at high temperature and are collected in the form of lead oxide dust by a high-temperature furnace dust collector, the volatilization rate of lead in the metallized pellets is 95-98.5%, and the content of lead in the lead oxide dust is 85-88.1%; !0 [00109] and the metallized pellets are smelted in the high-temperature furnace to provide molten iron with an iron grade greater than 94.8%, and the recovery rate of iron is greater than 92%.
[00110] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should be aware that the !5 present invention is not restricted by the above-mentioned examples. What is described in the above-mentioned examples and the description is merely to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various variations and modifications, which all fall within the scope of the claimed invention. The scope of protection claimed by the present invention is defined by the append claims and their equivalents.
Claims (8)
1. A method for treating lead slag with a rotary hearth furnace, characterized by comprising the following steps:
(1) pelletizing treatment, wherein pellets are prepared by crushing the lead slag into lead slag particles with particle sizes less than or equal to 0.074 mm, mixing the crushed lead slag with a reducing agent, a binder and industrial modified starch according to a ratio of 100: 20-30: 1-3: 2-4, and feeding the well-admixed mixture into a disc pelletizing machine wherein the total moisture content of the pellets is controlled at 9-12% during the pelletizing process, and the binder is water glass;
(2) baking reduction, wherein the pellets are ladded into the rotary hearth furnace through a vibrating distributor, wherein a first reduction zone of the rotary hearth furnace is a zone where lead sulfate is reduced to lead sulfide and moisture in the pellets is oven-dried, with the settings thereof that the temperature is 550-600 0 C and the reduction time of the first reduction zone is 25-30 min, and a second reduction zone is a reduction zone of ZnO, FeSiO3, Fe304 and Fe2O3, with the settings thereof that the temperature is 1230-1280C and the reduction time of the second reduction zone is 20-25 min; and
(3) slag-iron separation, wherein the total time for the rotary hearth furnace to rotate one round is 50-60 min; the metallized pellets containing metallic iron and lead sulfide are discharged from the rotary hearth furnace through a discharge area, and the metallization rate of iron is more than 80%; the metallized pellets are transferred to a high-temperature furnace, under the condition that the temperature of the high-temperature furnace is set at 1550-1600C, the smelting time is 1-2 h and a flux is added to adjust the quaternary alkalinity of the metallized pellets to 0.8-1 during high-temperature smelting,; and lead metal and iron metal after separation are obtained when the metallized pellets have been smelted in the high-temperature furnace.
2. The method for treating the lead slag with the rotary hearth furnace according to claim 1, wherein the ratio of the lead slag to the reducing agent to the binder to the industrial modified starch in step (1) is 100: 23-27: 1-3: 2-4.
3. The method for treating the lead slag with the rotary hearth furnace according to claim 1 or claim 2, wherein in step (1), the mixture is fed into the disc pelletizing machine and formulated as pellets with particle sizes of 8-12 mm, and the falling strength of the pellets is more than 8 times.
1/3
4. The method for treating the lead slag with the rotary hearth furnace according to any one of claims 1 to 3, wherein in step (2), it ensures a strong reducing atmosphere in the first reduction zone and the second reduction zone of the rotary hearth furnace by controlling an air-fuel ratio of a burner, wherein the concentration of CO is 7-14% and the concentration of oxygen is 0.8-1.7%.
5. The method for treating the lead slag with the rotary hearth furnace according to any one of claims 1 to 4, wherein in step (3), the high-temperature furnace is an electric arc furnace with graphite electrodes.
6. The method for treating the lead slag with the rotary hearth furnace according to any one of claims 1 to 5, wherein in step (3), the flux is quicklime.
7. The method for treating the lead slag with the rotary hearth furnace according to any one of claims 1 to 6, wherein the lead slag is waste lead slag produced during lead smelting in a blast furnace, and the lead slag contains 27-35% of TFe, 1.3-3.8% of lead and 2.4-6.2% of zinc.
8. The method for treating the lead slag with the rotary hearth furnace according to any one of claims 1 to 7, wherein the reducing agent is coal.
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Fig.1
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Fig.2
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