AU2022200483B1 - Method for recovering valuable metal from high-zinc and high-lead smelting slag - Google Patents
Method for recovering valuable metal from high-zinc and high-lead smelting slag Download PDFInfo
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- 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
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0066—Preliminary conditioning of the solid carbonaceous reductant
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
- C21B13/105—Rotary hearth-type furnaces
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/14—Multi-stage processes processes carried out in different vessels or 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
- C22B1/242—Binding; Briquetting ; Granulating with binders
-
- 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
-
- 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
-
- 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
- C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
- C21B2100/60—Process control or energy utilisation in the manufacture of iron or steel
- C21B2100/66—Heat exchange
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
- C21B2100/80—Interaction of exhaust gases produced during the manufacture of iron or steel with other 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
Disclosed in the present invention is a method for recovering valuable metals from a
high-zinc high-lead smelting slag, comprising the following steps: 1) mechanical
activation; 2) reduction in a rotary hearth furnace; 3) DRI output system; and 4) melting
and separating in an arc furnace. In the present invention, through the treatment, each
material can be imparted with an improved specific surface area and mixed uniformly; all
kinds of material are sufficiently contacted with each other, and are tightly bound
together due to the surface charges generated by the activation. The amount of the
binder can be reduced, thereby reducing cost; and the moisture content of pelletizing
and balling can be reduced, thus reducing the energy consumption. At the same time,
the balling rate can be increased and the strength can be increased. The reduction time
can be decreased, the volatilization rate of lead and zinc can be increased, and the
metallization rate of reduced pellets can be increased. The iron, zinc and lead in the
lead-zinc metallurgical slag can be recovered by this method, realizing the secondary
utilization of metallurgical slag. At the same time, high-temperature steam generated
during the reduction in the rotary hearth furnace and melting and separating in the arc
furnace is subjected to residual energy recover to generate electricity by the waste heat
to achieve green and low-carbon metallurgy.
Fig. 1
19
1/3
Lead-zinc Returning Reductive Limestone Removing Bentonite Sodium
slag material coal dust & ash humate
Fluegas
Fine grinding Conveying by Fine grinding Fine rinding Pneumatic Conveying Conveying
+ winnowing belt conveyor + winning + winnowing conveying by tank car by tank car
Batching chamber
Intensive
tepeatreecio
N turalegatueeto
|Green-pelet/dryingdlueecaseFa
Relletion by eeaHinc dutu
roar eazrt fu gassFg.
furraceura Naurlsa
by chaSteam/mergedn
Reucio b Hhtemperatureto
Cobutin-ssstn airrt Aire heas a
* NaturzSteam/merged
pipe network Boiler in lowh
14 temperature section
Comusio-asis|n Dust colce F
zicexicoery
DRIpelletuor L ein dust
Fig.1
Description
1/3
Lead-zinc Returning Reductive Limestone Removing Bentonite Sodium slag material coal dust &ash humate Fluegas
Fine grinding Conveying by Fine grinding Fine rinding Pneumatic Conveying Conveying + winnowing belt conveyor + winning + winnowing conveying by tank car by tank car
Batching chamber
Intensive
tepeatreecio furraceura Naurlsa Relletionby chaSteam/mergedn by eeaHinc dutu roar eazrt fu gassFg. Reucio b Hhtemperatureto
Cobutin-ssstn airrt N turalegatueeto Aire heas a
|Green-pelet/dryingdlueecaseFa * NaturzSteam/merged pipe network Boiler in lowh 14 temperature section
Dust colce F Comusio-asis|n zicexicoery
DRIpelletuor L ein dust
Fig.1
[0001] The present invention relates to the technical field of industrial waste residue recovery and utilization, and in particular to a method for recovering a valuable metal from a high-zinc and high-lead smelting slag.
[0002] Lead and zinc metal outputs in China have taken the first place in the world for many years. With the rapid development of product capacity, the disposal of various types of smelting slags in the production process gradually emerges, which often contain large amounts of lead, zinc and other valuable metals. The study on the recovery of valuable elements from a lead-zinc slag can not only alleviate the environmental pressure, but also effectively utilize secondary resources.
[0003] Since lead and zinc are mostly concomitant with each other during the protogenous formation of minerals, it leads to the common pattern of lead and zinc association in smelting process. If lead-zinc metallurgy as an industry wants to have a sound development, it must establish a closed and perfect production system, namely it must face and solve the severe problems of all kinds of slag treatment. !0 [0004] According to statistics, 7100 tons of waste slag is discharged per ten thousand tons of lead production from the lead smelting system, and 9600 tons of slag is discharged per ten thousand tons of zinc production. The slag yard is piled up as mountains with over 100 million tons. Therefore, the recycling and harmless treatment of lead-zinc smelting waste slag is the only way for the sustainable development of !5 lead-zinc industry in the future.
[0005] It is acknowledged that the terms "comprise", "comprises" and "comprising" 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.
[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] The present invention provides a method for recovering a valuable metal from a high-zinc and high-lead smelting slag or at least provides the public or industry with a useful choice.
[0008] According to one example embodiment there is provided a method for recovering a valuable metal from a high-zinc and high-lead smelting slag comprises the steps of:
[0009] 1) mechanical activation, comprising: crushing and grinding the high-zinc and high-lead smelting slag and a reducing agent by using a mechanical activation device !0 for mechanical activation to obtain a material with a particle size <0.074 mm and a content thereof greater than 80%; entering the material into a batching system, adding a binder, and then conveying them to a blending and pelletizing system to obtain green-balls, wherein the reducing agent is a mixture of limestone and reductive coal and the binder is a mixture of bentonite and sodium humate; and conveying the green-balls !5 into a chain grate for drying, dehydrating and preheating to meet the technical requirements for reduction of the green-balls in a rotary hearth furnace; pretreating the high-zinc and high-lead smelting slag and a reducing agent to obtain a material with a particle size <0.074 mm and a content thereof greater than 80%; entering the material into the batching system, adding the binder, and then conveying them to the mixing and pelletizing system to obtain green-balls of 8-16 mm with a moisture content of 9%-12%; and conveying the green-balls into the chain grate for drying, dehydrating and preheating to meet the technical requirements for reduction of the green-balls in a rotary hearth furnace; drying, dehydrating and preheating of the green-balls entering the chain grate is performed by using a flue gas furnace system, so that the physical water and the crystal water in the green-balls are removed and the oxidation of magnetite occurs at the same time, wherein the moisture content of the green-balls after drying is <1.5% and the temperature is <150°C;
[0010] 2) reduction in the rotary hearth furnace, comprising feeding the green-ball pellets qualified in accordance with the technical requirements continuously into the rotary hearth furnace and uniformly distributing them on an annular furnace bed; and with the rotation at a constant speed of a furnace bottom, successively passing the green-ball pellets through a charging zone, a drying zone, a fume exhausting zone, a preheating zone, a medium-temperature reduction zone, a high-temperature reduction zone and a discharging zone, wherein a reduction time of the green-ball pellets residing in the furnace is altered by adjusting the rotation speed of the furnace bottom, and the reduction time of the green-ball pellets in the furnace is 20-40 min;
[0011] subjecting the green-ball pellets to a reduction reaction in the rotary hearth furnace, with a large amount of lead and zinc escaping along with a high-temperature c0 flue gas, passing the high-temperature flue gas through a heat exchanger procedure, and finally entering into a bag dust collector, while obtaining a blazing DRI pellet ore at the same time;
[0012] 3) a DRI output system, wherein two charging buckets are provided below a screw discharger, the charging buckets are self-provided with a liftable sealing cover, !5 and each of the charging buckets has an independent rail transportation line; and each loading truck is transported to an arc furnace workshop via one of the rails; and
[0013] 4) melting and separating in an arc furnace: feeding the blazing DRI pellet ore into the arc furnace for melting and separating via a heat conveying system, and separating the slag from the iron to obtain molten iron and molten slag; and casting the molten iron into an iron block by a casting machine, and treating the molten slag to obtain a granulating slag.
[0014] The rotary hearth furnace is a rotary hearth furnace of a high-dense and alkaline-refractory material; and the physico-chemical properties of a high-dense and alkaline-refractory material are as follows:
[0015] Physico-chemical Properties of Magnesia Marks Units MS90 (Class B) Test standards MgO % >90 Main chemical components SiO2 % <4.8 GB/T5069 CaO % <2.5
Particle volume density t/m 3 3.18 GB/T2999
Bulk Density t/m 3 1.51 YB/T 5200
Loss on ignition Mass ratio % 0.3 YB/T 5203 Particle size mm 10 GB/T2007.7
[0016] Physico-chemical Properties of Castable Indices Items Castable I Castable II A1203 60 64 Fe2O3 !1.5 !1.2 3 Bulk density, g/cm >2.5 2.5 Release strength Id 3.5 4.0 (flexural strength), 3d 4.0 5.0 MPa 110°Cx24h 9 9 Flexural Strength, 1200°Cx3h 13 13 MPa 1500°Cx3h / 15 110°Cx24h 40 40 Compressive 1200°Cx3h 60 60 strength, MPa 1500°Cx3h 70 70 Linear change rate 1500°Cx3h ±0.5 ±0.5 CO erosion 500 0C Intact Intact resistance Temperature for 1400 0C 1450 0 C long-term use Furnace roof and Furnace roof and Part of application furnace wall in low furnace wall in high temperature section temperature section
[0017] Physico-chemical Properties of Anchoring brick Indices Items Low Temperature High temperature Section (L) section (H) A1203 55% >65% Fe2O3 !1.5% !1.5% 3 Volume Density / 2.4 g/cm Apparent porosity 22% <22% Softening onset temperature at 0.2 Mpa load 1470 0C 14800 C (4% Deformation temperature) Normal temperature compressive strength 45MPa :50MPa Linear change on reheating (1500 0C x 3 h) -0.4%-+0.1% +0.2% Maximum service temperature >14000 C >14500 C
[0018] The temperature of the reduction reaction in the rotary hearth furnace in the above-mentioned step 2) is 1200-1350 °C;
[0019] As a preferred technical solution, the content of zinc in the high-zinc and high-lead smelting slag in step 1) is 6%, and the content of lead in the high-zinc and high-lead smelting slag is 2%.
[0020] As a preferred technical solution, the high-lead and high-zinc smelting slag and the reducing agent, after being ground and thoroughly blended with the binder via a mixer, is subjected to pelletizing using a disc pelletizer so as to obtain green-balls of 8-16 mm with a moisture content of 9%-12%.
[0021] As a preferred solution, in step 2), the blazing DRI pellet ore is discharged out of the rotary hearth furnace via the screw discharger.
[0022] As a preferred technical solution, after the DRI pellets entering the charging bucket via the screw discharger, the liftable sealing cover is lowered to avoid secondary oxidation of the DRI pellets; after one charging bucket is filled up, it is automatically switched to another charging bucket for repetition of the above process.
[0023] As a preferred technical solution, each of the arc furnace for smelting and separating is respectively provided with 1 iron tapping hole and 1 slag tapping hole; each of the slag and iron tapping holes is respectively provided with one opening/plugging machine; tapping holes of different heights are provided by using c0 different specific gravities of the molten slag and the molten iron to separate the molten iron and the molten slag from each other; the molten iron is entered a casting machine for casting into blocks; and the molten slag is entered into a slag flushing pool to achieve slag-iron separation.
[0024] As a preferred technical solution, in the processes of reduction in the rotary hearth furnace of step 2) and melting and separating in the arc furnace of step 4), a large amount of high-temperature flue gas is generated, the temperature of the flue gas being as high as 1000-1150 0C, and a waste heat boiler is provided on an outlet flue for recovering the residual energy to utilize the waste heat for power generation, having great economic and energy-saving benefits.
[0025] Provided is a method for recovering a valuable metal from a high-zinc and high-lead smelting slag, which comprises: 1) mechanical activation, comprising: crushing and grinding the high-zinc and high-lead smelting slag and a reducing agent by using a mechanical activation device for mechanical activation to obtain a material with a particle size <0.074 mm and a content thereof greater than 80%; entering the material into a batching system, adding a binder, and then conveying them to a mixing and pelletizing system to obtain green-balls; and conveying the green-balls into a chain grate for drying, dehydrating and preheating to meet the technical requirements for reduction of the green-balls in a rotary hearth furnace;
[0026] 2) reduction in the rotary hearth furnace, comprising feeding the green-ball pellets qualified in accordance with the technical requirements continuously into the rotary hearth furnace and uniformly distributing them on an annular furnace bed; and with the rotation at a constant speed of a furnace bottom, successively passing the green-ball pellets through a charging zone, a drying zone, a fume exhausting zone, a preheating zone, a medium-temperature reduction zone, a high-temperature reduction zone and a discharging zone, wherein a reduction time of the green-ball pellets residing in the furnace is altered by adjusting the rotation speed of the furnace bottom, and the reduction time of the green-ball pellets in the furnace is 20-40 min;
[0027] subjecting the green-ball pellets to a reduction reaction in the rotary hearth c0 furnace, with a large amount of lead and zinc escaping along with a high-temperature flue gas, passing the high-temperature flue gas through a heat exchanger procedure, and finally entering a bag dust collector, while obtaining a blazing DRI pellet ore at the same time;
[0028] 3) a DRI output system, wherein two charging buckets are provided below a screw discharger, the charging buckets are self-provided with a liftable sealing cover, and each of the charging buckets has an independent rail transportation line; and the loading truck is transported to an arc furnace workshop via the rail; and
[0029] 4) melting and separating in an arc furnace: feeding the blazing DRI pellet ore into the arc furnace for melting and separating via a heat conveying system, and separating the slag from the iron to obtain molten iron and molten slag; casting the molten iron into an iron block by a casting machine, and treating the molten slag to obtain a granulating slag.
[0030] In the present invention, through the treatment, each material can be imparted with an improved specific surface area and mixed uniformly; all kinds of material are sufficiently contacted with each other, and tightly bound together due to the surface charges generated by the activation. The amount of the binder can be reduced, reducing cost; and the moisture content of pelletizing and balling can be decreased, lowering the energy consumption. At the same time, the balling rate can be increased and the strength can be improved. The reduction time can be shortened, the volatilization rate of lead and zinc can be increased, and the metallization rate of reduced pellets can be increased.
[0031] The iron, zinc and lead in the lead-zinc metallurgical slag can be recovered by this method, realizing the secondary utilization of metallurgical slag. At the same time, high-temperature steam generated during the reduction in the rotary hearth furnace and melting and separating in the arc furnace is subjected to residual energy recover to generate electricity by the waste heat to achieve green and low-carbon metallurgy.
[0032] In view of the close co-existence of minerals and fine embedded particle size in the high-zinc and high-lead smelting slag, it is difficult to separate and recover iron and lead and zinc by conventional methods. Through the steps of mechanical activation and c0 batching, reduction in the high-dense and alkaline-refractory rotary hearth furnace, conveying the pellet ore into the arc furnace by DRI output system for the combined process of melting and separation, the lead-zinc dust is recovered through high-temperature flue gas; through the melting and separating, metallic iron and molten slag are obtained; the obtained iron grade is >93%, the recovery rate is more than 85%, the zinc removal rate is >88%, and the lead removal rate is >85%, realizing the high-efficiency utilization of iron, zinc and lead and avoiding the waste of resources. At the same time, the high-temperature flue gas produced by the rotary hearth furnace system and arc furnace system subjected to residual energy recover to generate electricity by the waste heat, which greatly improves the utilization efficiency of fossil energy and realizes green and low-carbon metallurgy, with great economic and social benefits.
[0033] FIG.1 is a process flow chart of the reduction in a rotary hearth furnace of the present invention;
[0034] FIG. 2 is a diagram showing an arrangement of a DRI output system of the present invention; and
[0035] FIG.3 is a process flow chart of the melting and separating in an arc furnace of the present invention;
[0036] A method for recovering a valuable metal from a high-zinc and high-lead smelting slag comprises the steps of:
[0037] 1) mechanical activation, comprising: crushing and grinding the high-zinc and high-lead smelting slag and a reducing agent by using a mechanical activation device for mechanical activation to obtain a material with a particle size <0.074 mm and a content thereof greater than 80%; entering the material into a batching system, adding a binder, and then conveying them to a mixing and pelletizing system to obtain green-balls; and conveying the green-balls into a chain grate for drying, dehydrating and preheating to meet the technical requirements for reduction of the green-balls in a !0 rotary hearth furnace;
[0038] 2) reduction in the rotary hearth furnace, comprising feeding the green-ball pellets qualified in accordance with the technical requirements continuously into the rotary hearth furnace and uniformly distributing them on an annular furnace bed; and with the rotation at a constant speed of a furnace bottom, successively passing the !5 green-ball pellets through a charging zone, a drying zone, a fume exhausting zone, a preheating zone, a medium-temperature reduction zone, a high-temperature reduction zone and a discharging zone, wherein a reduction time of the green-ball pellets residing in the furnace is altered by adjusting the rotation speed of the furnace bottom, and the reduction time of the green-ball pellets in the furnace is 20-40 min;
[0039] subjecting the green-ball pellets to a reduction reaction in the rotary hearth furnace, with a large amount of lead and zinc escaping along with a high-temperature flue gas, passing the high-temperature flue gas through a heat exchanger procedure, and finally entering into a bag dust collector, while obtaining a blazing DRI pellet ore at the same time;
[0040] 3) a DRI output system, wherein two charging buckets are provided below a screw discharger, the charging buckets are self-provided with a liftable sealing cover, and each of the charging buckets has an independent rail transportation line; and the loading truck is transported to an arc furnace workshop via the rail; and
[0041] 4) melting and separating in an arc furnace: feeding the blazing DRI pellet ore into the arc furnace for melting and separating via a heat conveying system, and separating the slag from the iron to obtain molten iron and molten slag; casting the molten iron into an iron block by a casting machine, and treating the molten slag to obtain a granulating slag.
[0042] It adopts a high-dense and alkaline-refractory material inside a rotary hearth furnace; and
[0043] The content of zinc in the high-zinc and high-lead smelting slag in step 1) is> c0 6%, and the content of lead in the high-zinc and high-lead smelting slag is 2%.
[0044] The high-lead and high-zinc smelting slag and the reducing agent, after being ground and thoroughly mixed with the binder via a mixer, is subjected to pelletizing using a disc pelletizer so as to obtain green-balls of 8-16 mm with moisture content of 9%-12%.
[0045] In step 1), drying, dehydrating and preheating the green-balls entering the chain grate is performed by using a flue gas furnace system, so that the physical water and the crystal water in the green-balls are removed and the oxidation of magnetite occurs at the same time, wherein the moisture content of the green-balls after drying is <1.5% and the temperature is <1500 C.
[0046] In step 2), the blazing DRI pellet ore is discharged out of the rotary hearth furnace via the screw discharger.
[0047] After the DRI pellets entering the charging bucket via the screw discharger, the liftable sealing cover is lowered to avoid secondary oxidation of the DRI pellets; after one charging bucket is filled up, it is automatically switched to another charging bucket for the repetition of the process.
[0048] Each of the arc furnace for smelting and separating is respectively provided with 1 iron tapping hole and 1 slag tapping hole; each of the slag and iron tapping holes is respectively provided with one opening/plugging machine; tapping holes of different heights are provided by using different specific gravities of the molten slag and the molten iron to separate the molten iron and the molten slag; the molten iron is entered a casting machine for casting into blocks; and the molten slag is entered a slag flushing pool to achieve slag-iron separation.
[0049] In the processes of reduction in the rotary hearth furnace of step 2) and melting and separating in the arc furnace of step 4), a large amount of high-temperature flue gas, with the temperature of as high as 1000-1150 0C ,is generated, and a waste heat boiler is provided on an outlet flue for recovering the residual energy and utilizing the waste heat for power generation, having great economic and energy-saving benefits.
[0050] The reducing agent is a mixture of limestone and reductive coal; and the binder c0 is a mixture of bentonite and sodium humate.
[0051] In order to make the technical means, creative features, purpose and efficacy of the present invention more apparent, the present invention is further described in combination with specific embodiments.
[0052] Example
[0053] The lead-zinc smelting slag used is taken from a smelter in Huading XX smelting plant, Yunnan Province, with the chemical composition as follows:
[0054] Composition analysis of high-zinc high-lead zinc smelting slag/%
TFe SiO 2 CaO A1203 MgO Zn Pb Sn As2O3 S
27.69 24.84 12.30 6.75 1.94 13.80 4.53 0.58 0.72 1.17
[0055] 1. The high-zinc and high-lead and zinc smelting slag, limestone and reduced coal were fed by a grab bucket and transported to a fine grinding chamber via a large-inclination angle belt conveyor. The fine grinding chamber was provided with three grinding machines respectively corresponding to the high-zinc and high-lead-zinc smelting slag, the limestone and the reductive coal. The content of material <200 mesh in the finely ground material was >80%.
[0056] 2. The finely ground material was conveyed to a bag dust collector at a top of a batching chamber by a fan system, and the material was conveyed to a corresponding batching bin by a discharge screw to be batched in proportion. Bentonite and sodium humate were conveyed from a tank car to the batching bin. The bentonite and sodium humate were used as a binder, wherein the batching ratio of the high-zinc high-lead-zinc smelting slag, limestone, reductive coal and the binder was 100: 20: 5: 3, and the batching ratio of bentonite and sodium humate in the binder was 75: 25. After the batching was completed, the characteristics of poor surface hydrophilicity and poor pelletizing performance of the lead-zinc slag due to post-high temperature can be improved, and the quality of green-balls can be improved.
[0057] 3. The material was transported to a double-roller ball mill of the mechanical activation system by a batching belt below the bin of the batching chamber to perform the mechanical activation. Then, the material was conveyed to an intensive kneader c0 chamber for sufficient blending. The mixture was fed to a disc pelletizer for pelletizing, so as to obtain green-balls of 8-16 mm with a moisture content of 9%-12%.
[0058] 4. The green-balls were fed into a chain grate via a shuttle distributor and a wide belt. The heat source required by the chain grate was mainly provided by a flue gas furnace, with the flue gas temperature of 300-350C. After drying, the moisture content was s 1.5%, the temperature of the pellets was <1500 C. The dried pellets were discharged via a slide plate and conveyed to a rotary hearth furnace.
[0059] 5. The pellets were entered the high-dense alkaline-refractory rotary hearth furnace, and passed through a preheating zone, a medium temperature zone, a high temperature zone and a cooling zone, respectively. A mixed coal gas, a preheated combustion-assisting air and a secondary air were introduced into the rotary hearth furnace. The temperature distribution in the furnace and the atmosphere in the furnace can be controlled by adjusting various regulating valves. The green-balls were reduced by calcination for 20-30 min, and the DRI pellets were discharged via a screw discharger at a pellet temperature of 1000 0C. At the same time, the dust of zinc oxide/ lead oxide was escaped with high temperature flue gas, and finally entered the bag collector via the flue gas recovery system.
[0060] 6. The blazing DRI pellets were entered charging buckets via the screw discharger. Two loading truck transportation lines were independent from each other, when the charging bucket of one side was filled up, a self-provided sealing cover was automatically lowered and the loading truck was transported to an arc furnace workshop. Then the unloading device is automatically switched to another charging bucket for receiving material circularly. The high-temperature DRI pellets produced by the rotary hearth furnace were periodically and stably transferred to a storage bin for the arc furnace.
[0061] After the smelting and separating operation, since each of the arc furnace was respectively provided with 1 tapping hole and 1 slag tapping hole. Each of the slag and iron tapping holes was respectively provided with one opening/plugging machine. Tapping holes of different heights were provided by using different specific gravities of the molten slag and the molten iron to separate the molten iron and the molten slag. c0 The molten iron can be entered a casting machine for casting into blocks; and the molten slag can be entered a slag flushing pool to achieve slag-iron separation. Final product obtained: iron grade> 93%, recovery exceeding 85%, zinc removal rate > 88%, and lead removal rate > 85%.
[0062] 7. In the processes of reduction in the rotary hearth furnace and melting and separating in the arc furnace, a large amount of high-temperature flue gas, with the temperature of as high as 1000-1150 0C, was generated. A waste heat boiler was provided on an outlet flue for recovering the residual energy, and utilizing the waste heat for power generation, thereby having great economic and energy-saving benefits.
[0063] In this example, 1 rotary hearth furnace and 2 arc furnaces were provided; a set of waste heat boiler was provided downstream of the rotary hearth furnace; and 1 set of waste heat boiler was provided downstream each arc furnace.
[0064] The example was involved in the following comparative experiments.
[0065] Experimental group 1 used the method of the above example.
[0066] Experimental group 2 adopted the method of the above example, but the
content of the material with a particle size <0.074 mm after fine grinding accounts for
less than 50%. The material was sent to a batching mixer for mixing, and was fed into a disc pelletizer for pelletizing, so as to obtain 8-16 mm green-balls;
[0067] Through the test, following table is obtained
Iron Recovery Zinc Lead Binder Pelletizing Balling Reduction Pellet drop Balling
grade rate removal removal dosage moisture% rate time strength pressure
rate rate
Experimental 93 92 92 88 3 10 88 34 4.4 times/ 25.3
Group 1 (pellet- 0.5m) N/pellet
Experimental 90 78 87 80 4 14 85 38 3.25 times/ 20.1N/pellet
Group 2 (pellet- 0.5m)
[0068] From the above table, it can be seen that, through the treatment, each material can be imparted with an improved specific surface area and mixed uniformly; all kinds of material are sufficiently contacted with each other, and tightly bound together due to the surface charges generated upon the activation. The amount of the binder can be reduced, thereby lowering cost; and the moisture content of pelletizing and balling can be reduced, thereby reducing the energy consumption. At the same time, the balling rate can be increased and the strength can be increased. The reduction time can be shortened, the volatilization rate of lead and zinc can be increased, and the metallization rate of reduced pellets can be increased;
[0069] The foregoing has shown and described the basic principles, principal features, and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the present invention, and that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims. It is intended that the scope of the present invention should be defined by the claims appended hereto and their equivalents.
Claims (8)
1. A method for recovering a valuable metal from a high-zinc and high-lead smelting slag, comprising the steps of:
1) mechanical activation, comprising: crushing and grinding the high-zinc and high-lead smelting slag and a reducing agent by using a mechanical activation device for mechanical activation to obtain a material with a particle size <0.074 mm and a content thereof greater than 80%; entering the material into a batching system, adding a binder, and then conveying them to a mixing and pelletizing system to obtain green-balls, wherein the reducing agent is a mixture of limestone and reductive coal and the binder is a mixture of bentonite and sodium humate; and conveying the green-balls into a chain grate for drying, dehydrating and preheating to meet the technical requirements for reduction of the green-balls in a rotary hearth furnace; drying, dehydrating and preheating of the green-balls entering the chain grate is performed by using a flue gas furnace system, so that the physical water and the crystal water in the green-balls are removed and the oxidation of magnetite occurs at the same time, wherein the moisture content of the green-balls after drying is <1.5% and the temperature is <150°C;
2) reduction in the rotary hearth furnace, wherein the rotary hearth furnace is a rotary hearth furnace of a high-dense and alkaline-refractory material; the step comprising: feeding the green-ball pellets qualified in accordance with the technical requirements continuously into the rotary hearth furnace and uniformly distributing them on an annular furnace bed; and with the rotation at a constant speed of a furnace bottom, successively passing the green-ball pellets through a charging zone, a drying zone, a fume exhausting zone, a preheating zone, a medium-temperature reduction zone, a high-temperature reduction zone and a discharging zone, wherein a reduction time of the green-ball pellets residing in the furnace is altered by adjusting the rotation speed of the furnace bottom, and the reduction time of the green-ball pellets in the furnace is 20-40 min;
subjecting the green-ball pellets to a reduction reaction in the rotary hearth furnace, with a large amount of lead and zinc escaping along with a high-temperature flue gas, passing the high-temperature flue gas through a heat exchanger procedure, and finally entering into a bag dust collector, while obtaining a blazing DRI pellet ore at the same time;
3) a DRI output system, wherein two charging buckets are provided below a screw discharger, the charging buckets are self-provided with a liftable sealing cover, and each of the charging buckets has an independent rail transportation line; and each loading truck is transported to an arc furnace workshop via one of the rails; and
4) melting and separating in an arc furnace: feeding the blazing DRI pellet ore into the arc furnace for melting and separating via a heat conveying system, and separating the slag from the iron to obtain molten iron and molten slag; casting the molten iron into an iron block by a casting machine, and treating the molten slag to obtain a granulating slag.
2. The method for recovering a valuable metal from a high-zinc and high-lead smelting slag of claim 1, wherein the mechanical activation device is one or more selected from the group consisting of a vertical mill, a stirred mill, a roll ball mill, and a ball mill.
3. The method for recovering a valuable metal from a high-zinc and high-lead smelting slag of claim 1 or claim 2, wherein the content of zinc in the high-zinc and high-lead smelting slag in step 1) is 6%, and the content of lead in the high-zinc and high-lead smelting slag is 2%.
4. The method for recovering a valuable metal from a high-zinc and high-lead smelting slag of any one of claims 1 to 3, wherein after fine grinding the high-lead and high-zinc smelting slag and the reducing agent and thoroughly mixing them with the binder via a mixer, it is subjected to pelletizing using a disc pelletizer so as to obtain green-balls of 8-16 mm with moisture content of 9%-12%.
5. The method for recovering a valuable metal from a high-zinc and high-lead smelting slag of any one of claims 1 to 4, wherein in step 2), the blazing DRI pellet ore is discharged out of the rotary hearth furnace via the screw discharger.
6. The method for recovering a valuable metal from a high-zinc and high-lead smelting slag of any one of claims 1 to 5, wherein in the step 3), after the DRI pellets ore entering the charging bucket via the screw discharger, the liftable sealing cover is lowered to avoid secondary oxidation of the DRI pellets; after one charging bucket is filled up, it is automatically switched to another charging bucket for the repetition of the above process.
7. The method for recovering a valuable metal from a high-zinc and high-lead smelting slag of any one of claims 1 to 6, wherein each of the arc furnace for smelting and separating is respectively provided with 1 iron tapping hole and 1 slag tapping hole; each of the slag and iron tapping holes is respectively provided with one opening/plugging machine; tapping holes of different heights are provided by using different specific gravities of the molten slag and the molten iron to separate the molten iron and the molten slag; the molten iron is entered a casting machine for casting into blocks; and the molten slag is entered a slag flushing pool to achieve slag-iron separation.
8. The method for recovering a valuable metal from a high-zinc and high-lead smelting slag of any one of claims 1 to 7, wherein in the processes of reduction in the rotary hearth furnace of step 2) and melting and separating in the arc furnace of step 4), a large amount of high-temperature flue gas is generated, with the temperature of as high as 1000-1150 0C, and a waste heat boiler is provided on an outlet flue for recovering the residual energy and utilizing the waste heat for power generation, thereby having great economic and energy-saving benefits.
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Fig.1
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Fig.2
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001152222A (en) * | 1999-11-30 | 2001-06-05 | Nippon Steel Corp | Discharge device for reducing furnace |
| US20080236335A1 (en) * | 2007-04-02 | 2008-10-02 | Gary Edward Metius | Method and system for the supply of hot direct reduced iron for multiple uses |
| CN106148717A (en) * | 2016-08-01 | 2016-11-23 | 江苏省冶金设计院有限公司 | The processing method of direct-reduction lead skim and processing system |
| CN112522521A (en) * | 2020-11-20 | 2021-03-19 | 云南华鼎再生资源开发有限公司 | Method for treating lead slag by rotary hearth furnace |
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| CN105671329B (en) * | 2016-03-25 | 2018-07-13 | 江苏省冶金设计院有限公司 | Handle the rotary hearth furnace and method of lead and zinc smelting dreg |
| CN111979424A (en) * | 2020-08-24 | 2020-11-24 | 云南华鼎再生资源开发有限公司 | Metallurgy method of high-sulfur lead slag containing zinc and tin |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001152222A (en) * | 1999-11-30 | 2001-06-05 | Nippon Steel Corp | Discharge device for reducing furnace |
| US20080236335A1 (en) * | 2007-04-02 | 2008-10-02 | Gary Edward Metius | Method and system for the supply of hot direct reduced iron for multiple uses |
| CN106148717A (en) * | 2016-08-01 | 2016-11-23 | 江苏省冶金设计院有限公司 | The processing method of direct-reduction lead skim and processing system |
| CN112522521A (en) * | 2020-11-20 | 2021-03-19 | 云南华鼎再生资源开发有限公司 | Method for treating lead slag by rotary hearth furnace |
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