Treatment process of zinc leaching residues

Abstract

The invention discloses a zinc leaching slag treatment process which comprises the following steps: step 1, drying treatment; step 2, smelting in an oxygen-enriched side-blown converter: grabbing dried leaching slag, a flux and pea coal into respective intermediate bins through a grab bucket, and adding the materials into the oxygen-enriched side-blown converter from a feed port; oxygen-enriched air is blown into a slag layer from a molten pool area of a furnace body of the oxygen-enriched side-blown furnace through a primary tuyere located at the position 0.50 m below a standing melt plane; step 3, fuming treatment; zinc leaching residues are treated through an oxygen-enriched side-blown molten pool smelting method, the chemical reaction is violent, and the metal reduction rate and volatilization rate are increased; the comprehensive metal recovery rate is improved; the comprehensive energy consumption is low, and the crushed coal with lower price is adopted to replace coke, so that the energy consumption is reduced; the flue gas amount is small, oxygen-enriched combustion is adopted, the flue gas amount is reduced, heat taken away by flue gas is small, and the heat utilization rate is increased; the treatment process adopts micro-negative pressure operation, the unorganized emission is less, the working environment is good, and the generated SO2 flue gas can directly enter a desulfurization acid-making system to produce industrial sulfuric acid.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal smelting, and in particular relates to a treatment process for zinc leaching slag. Background Art

[0002] According to the different raw materials and leaching methods, the wet zinc smelting process is divided into the conventional leaching process of zinc roasted sand, the hot acid leaching process of zinc roasted sand and the direct oxygen pressure leaching process of zinc concentrate. At present, most of the wet zinc smelting production in my country is the conventional leaching process of zinc roasted sand and the hot acid leaching process. Regardless of the leaching process, various types of leaching slag will be produced to varying degrees, such as conventional leaching slag (leaching slag produced by the two-stage intermediate leaching process, leaching slag produced by the intermediate leaching-low leaching process, etc.) and hot acid leaching slag (iron alum slag produced by iron removal, lead and silver slag produced by hot acid leaching), etc. The production of 1 ton of electrolytic zinc will produce 1.05 tons of leaching slag, and the slag production is huge.

[0003] For conventional leaching slag, considering the zinc recovery rate, domestically, rotary kilns, fuming furnaces and other equipment are mostly used for treatment; limited by technical, economic, and geographical conditions, hot acid leaching slag is mostly stored in a stockpile, which on the one hand occupies land resources and has an adverse impact on the surrounding environment; on the other hand, the valuable metal resources in the slag are not effectively utilized. The comprehensive utilization and harmless treatment of hot acid leaching slag is a bottleneck problem in the industry's production.

[0004] The existing rotary kiln treatment method, fuming furnace treatment method, vortex smelting method, Kivcet-fuming furnace combined method have the problems of poor comprehensive metal recovery effect, high energy consumption, serious environmental pollution, high requirements for raw materials entering the furnace, etc. Therefore, the present invention proposes a treatment process for zinc leaching slag. Summary of the invention

[0005] The object of the present invention is to provide a treatment process for zinc leaching slag to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a zinc leaching slag treatment process, step 1: drying treatment: S11: the zinc leaching slag with a water content of 35% produced by the wet smelting system is transported and unloaded into the wet slag storage, sent to the upper area of ​​the screw conveyor by a loader, enters the feeding belt through a shaftless screw, and enters the drying kiln;

[0007] S12: The qualified materials after drying contain 15%-18% water, are discharged from the discharge hopper, and are sent to the dry residue storage bin via a belt conveyor for 10 days; the drying tail gas is purified by a bag dust collector and then discharged;

[0008] Step 2: Oxygen-enriched side-blown furnace smelting:

[0009] S21: The dried leached slag, flux and granular coal are grabbed into respective intermediate bins by grabbing buckets and dropped onto respective weighing belts for measurement. After batching, the materials are continuously added into the oxygen-enriched side-blown furnace from the feed port via a belt conveyor;

[0010] S22: At the same time, in the molten pool area of ​​the oxygen-enriched side-blown furnace body, oxygen-enriched air is blown into the slag layer through the primary tuyere located 0.50m below the stationary melt plane, ensuring strong stirring of the slag melt, rapid and uniform distribution of charge particles in the melt, rapid melting of leached slag, rapid decomposition of sulfate, and completion of the chemical reaction process. The high-temperature molten slag is continuously discharged through siphon along the furnace of the oxygen-enriched side-blown furnace, and enters the fuming furnace through the slag chute connector and the chute for fuming;

[0011] S23: The sulfur in the decomposed sulfate escapes from the melt in the form of sulfur dioxide and enters the gas phase. It passes through the exhaust pipe on the top of the furnace and enters the waste heat boiler to recover waste heat. It then enters the electric dust collector to collect dust. The smoke is sent to the lead smelting system in the plant area, and the flue gas enters the acid making and desulfurization and denitrification systems.

[0012] Step 3: Fuming treatment: S31: The molten slag from the oxygen-enriched side-blowing furnace flows through the chute by gravity and enters two fuming furnaces in different time periods to volatilize zinc and lead. The fuel pulverized coal is supplied by the pulverized coal preparation workshop. The pulverized coal is fed into the nozzle by the spiral coal feeder device at the bottom of the pulverized coal intermediate bin together with the primary air, and then mixed with the secondary air in the nozzle and blown into the fuming furnace;

[0013] S32: The hot slag reacts with pulverized coal and air, and the dusty flue gas produced is recycled by the waste heat boiler, cooled by the surface cooler, and collected by the bag filter. The collected secondary zinc oxide dust is sent to the zinc system to recover valuable metals;

[0014] S33: The flue gas after dust collection is sent to the ionic liquid for desulfurization, and the high-concentration SO2 is sent to the one-turn-one-absorption acid-making system. After acid making, the tail gas is further desulfurized and denitrified by the ionic liquid before it meets the emission standards.

[0015] Preferably, in step 1, the heat source of the rotary drying drum is natural gas, and the drying temperature is 700-750°C.

[0016] Preferably, the smoke dust collected by the waste heat boiler and the electrostatic precipitator is sent to the lead smelting system in the plant to recover the lead.

[0017] Preferably, the slag produced by the fuming furnace can be sent to a slag dump for temporary storage and sale after water crushing and precipitation.

[0018] Preferably, the molten pool area of ​​the furnace body is an area surrounded by a first-layer copper water jacket assembly and a second-layer copper water jacket assembly, and a plurality of primary air inlets are provided, which are symmetrically distributed on both sides of the first-layer copper water jacket assembly. The furnace body also includes a reburning zone, which is an area surrounded by a third-layer copper water jacket assembly and a fourth-layer steel water jacket assembly. Secondary air inlets for supplying secondary air are installed on both sides of the three-layer copper water jacket assembly, where Pb, Zn, S, and CO in the furnace gas undergo an oxidation reaction with the blown air, and part of the heat released by the oxidation reaction is returned to the molten pool area.

[0019] Preferably, in order to reduce the amount of fine charge material being carried away by the furnace gas, the two-layer copper water jacket assembly and the three-layer copper water jacket assembly are tilted outward, and the furnace width is increased to reduce the air flow velocity and the smoke rate.

[0020] Preferably, the furnace hearth is composed of refractory materials built in a steel trough welded with outer steel plates, the inner layer of the refractory material is built with magnesia-chrome bricks, and the outer layer is built with ordinary high-alumina bricks. The masonry at the bottom of the furnace hearth is in an inverted arch shape, and insulation material is filled between the refractory material and the steel outer shell. In order to ensure heat exchange in the furnace hearth, the furnace hearth is built with high and low furnace bottoms, reducing the volume of the furnace hearth to maintain the thermal balance of the furnace hearth. A siphon slag discharge port is provided at the front end of the furnace hearth, and the slag is continuously discharged during production.

[0021] Preferably, the furnace roof is made of a box-type water jacket welded from steel plates, the inner surface of the furnace is provided with steel hooks to hang refractory linings, and the exhaust pipe adopts a membrane water-cooled wall structure to reduce the amount of smoke and ensure that the melt does not enter the waste heat boiler.

[0022] Compared with the prior art, the invention has the following beneficial effects: the zinc leaching slag is treated by oxygen-enriched side-blowing molten pool smelting method, the chemical reaction is intense, the metal reduction rate and volatilization rate are improved; thus, the comprehensive metal recovery rate is improved; the comprehensive energy consumption is low, and the relatively low-priced crushed coal is used instead of coke to reduce energy consumption;

[0023] Small amount of flue gas, oxygen-enriched combustion is adopted to reduce the amount of flue gas, less heat is carried away by the flue gas, and the heat utilization rate is improved;

[0024] It has good environmental protection effect, the treatment process adopts micro-negative pressure operation, less unorganized emissions, and a good working environment. The generated SO2 flue gas can directly enter the desulfurization and acid production system to produce industrial sulfuric acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a front view and cross-sectional schematic diagram of the oxygen-enriched side-blown furnace used in the present invention;

[0026] Figure 2 It is a schematic diagram of the cross-sectional structure of the oxygen-enriched side-blown furnace used in the present invention;

[0027] Figure 3 is a process flow chart of the present invention;

[0028] In the figure: 1. Feed inlet; 2. Primary air inlet; 3. First-layer copper water jacket assembly; 4. Second-layer copper water jacket assembly; 5. Third-layer copper water jacket assembly; 6. Fourth-layer molten steel jacket assembly; 7. Secondary air inlet; 8. Slag chute connector; 9. Furnace; 10. Exhaust pipe. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] See also Figures 1 to 3 ,This embodiment provides a technical solution: a treatment process for zinc leaching slag, step 1: drying treatment: S11: the zinc leaching slag with a water content of 35% produced by the wet smelting system is transported and unloaded into the wet slag storage, sent to the upper area of ​​the screw conveyor by a loader, enters the feeding belt through a shaftless screw, and enters the drying kiln;

[0032] S12: The qualified materials after drying contain 15%-18% water, are discharged from the discharge hopper, and are sent to the dry residue storage bin via a belt conveyor for 10 days; the drying tail gas is purified by a bag dust collector and then discharged;

[0033] Step 2: Oxygen-enriched side-blown furnace smelting:

[0034] S21: The dried leached slag, flux and granular coal are grabbed into respective intermediate bins by grabbing buckets and dropped onto respective weighing belts for measurement. After batching, the materials are continuously fed into the oxygen-enriched side-blowing furnace from the feed port 1 via a belt conveyor;

[0035] S22: At the same time, in the molten pool area of ​​the oxygen-enriched side-blown furnace body, oxygen-enriched air is blown into the slag layer through the primary tuyere 2 located 0.50m below the stationary melt plane, ensuring strong stirring of the slag melt, rapid and uniform distribution of charge particles in the melt, rapid melting of leached slag, rapid decomposition of sulfate, and completion of the chemical reaction process. The high-temperature molten slag is continuously discharged through siphon along the furnace 9 of the oxygen-enriched side-blown furnace, and enters the fuming furnace through the slag chute connector 8 and the chute for fuming;

[0036] S23: The sulfur in the decomposed sulfate escapes from the melt in the form of sulfur dioxide and enters the gas phase, passes through the exhaust pipe 10 on the top of the furnace, enters the waste heat boiler to recover waste heat, and then enters the electric dust collector to collect dust. The smoke is sent to the lead smelting system in the plant area, and the flue gas enters the acid making and desulfurization and denitrification system;

[0037] Step 3: Fuming treatment: S31: The molten slag from the oxygen-enriched side-blowing furnace flows through the chute by gravity and enters two fuming furnaces in different time periods to volatilize zinc and lead. The fuel pulverized coal is supplied by the pulverized coal preparation workshop. The pulverized coal is fed into the nozzle by the spiral coal feeder device at the bottom of the pulverized coal intermediate bin together with the primary air, and then mixed with the secondary air in the nozzle and blown into the fuming furnace;

[0038] S32: The hot slag reacts with pulverized coal and air, and the dusty flue gas produced is recycled by the waste heat boiler, cooled by the surface cooler, and collected by the bag filter. The collected secondary zinc oxide dust is sent to the zinc system to recover valuable metals;

[0039] S33: The flue gas after dust collection is sent to the ionic liquid for desulfurization, and the high-concentration SO2 is sent to the one-turn-one-absorption acid-making system. The tail gas after acid production is then desulfurized and denitrated by the ionic liquid before being discharged in compliance with the standards. In this embodiment, preferably, in step one, the heat source of the rotary drying drum is natural gas, and the drying temperature is 700-750°C. In this embodiment, preferably, the dust collected by the buried scraper conveyor configured by the waste heat boiler and the electrostatic precipitator is sent to the lead smelting system in the factory to recover lead. In this embodiment, preferably, the slag produced by the fuming furnace can be sent to the slag yard for temporary storage and sale after water crushing and precipitation. In this embodiment, preferably, the molten pool area of ​​the furnace body is an area surrounded by a first layer of copper water jacket assembly 3 and a second layer of copper water jacket assembly 4, a plurality of primary air inlets 2 are provided, symmetrically distributed on both sides of the first layer of copper water jacket assembly 3, and the furnace body also includes a reburning area, which is an area surrounded by a third layer of copper water jacket assembly 5 and a fourth layer of steel water jacket assembly 6, and secondary air inlets 7 for feeding secondary air are installed on both sides of the third layer of copper water jacket assembly 5, where Pb, Zn, S, CO in the furnace gas undergo oxidation reaction with the blown air, and part of the heat released by the oxidation reaction returns to the molten pool area; and the feeding of secondary air is quantitative to maintain the atmosphere requirements in the furnace. In this embodiment, preferably, in order to reduce the fine charge being carried away by the furnace gas, the second layer of copper water jacket assembly 4 and the third layer of copper water jacket assembly 5 are tilted outward, and the furnace width is increased to reduce the air flow velocity and reduce the smoke rate. In this embodiment, preferably, the furnace 9 is composed of refractory materials built in a steel trough welded with outer steel plates, the inner layer of the refractory materials is built with magnesia-chrome bricks, and the outer layer is built with ordinary high-aluminum bricks. The bottom masonry of the furnace 9 is inverted arch shape, and insulation materials are filled between the refractory materials and the steel shell; in order to ensure heat exchange in the furnace 9, the furnace is built into a high and low furnace bottom, reducing the volume of the furnace to maintain the thermal balance of the furnace, and the front end of the furnace 9 is provided with a siphon slag discharge port, and the slag is continuously discharged during production. In this embodiment, preferably, the furnace top is made of a box-type water jacket welded with steel plates, and the inner surface of the furnace is provided with steel hooks to hang the refractory lining, and the exhaust pipe 10 adopts a membrane water-cooled wall structure to reduce the amount of smoke and ensure that the melt does not enter the waste heat boiler.

[0040] Although embodiments of the present invention have been shown and described (see the above detailed description for details), it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for treating zinc leaching slag, characterized in that: Step 1: Drying: S11: The zinc leaching slag with a water content of 35% produced by the hydrometallurgical system is transported and unloaded into the wet slag storage, and then sent to the area above the screw conveyor by the loader, and then enters the feeding belt through the shaftless screw and enters the drying kiln; S12: The qualified materials after drying contain 15%-18% water, are discharged from the discharge hopper, and are sent to the dry residue storage bin via a belt conveyor for 10 days; the drying tail gas is purified by a bag filter and then discharged; Step 2: Oxygen-enriched side-blown furnace smelting: S21: the dried leached slag, flux and granular coal are caught and placed in respective intermediate bins, and then fall onto respective weighing belts for measurement. After batching, they are continuously fed into the oxygen-enriched side-blown furnace from the feed port (1) via a belt conveyor; S22: At the same time, in the molten pool area of ​​the oxygen-enriched side-blown furnace body, oxygen-enriched air is blown into the slag layer through a primary tuyere (2) located 0.50 m below the stationary melt plane to ensure strong stirring of the slag melt, so that the charge particles are quickly and evenly distributed in the melt, the leached slag is quickly melted, and the sulfate is quickly decomposed to complete the chemical reaction process. The high-temperature molten slag is continuously discharged through a siphon along the furnace cylinder (9) of the oxygen-enriched side-blown furnace and enters the fuming furnace through the slag chute connecting piece (8) and the chute for fuming; S23: The sulfur in the decomposed sulfate escapes from the melt in the form of sulfur dioxide into the gas phase, passes through the exhaust pipe (10) on the top of the furnace, enters the waste heat boiler to recover waste heat, and then enters the electric dust collector to collect dust. The smoke is sent to the lead smelting system in the plant area, and the flue gas enters the acid making and desulfurization and denitrification systems; Step 3: Fuming treatment: S31: The molten slag from the oxygen-enriched side-blowing furnace flows through the chute by gravity and enters two fuming furnaces in different time periods to volatilize zinc and lead. The fuel pulverized coal is supplied by the pulverized coal preparation workshop. The pulverized coal is fed into the nozzle by the spiral coal feeder device at the bottom of the pulverized coal intermediate bin together with the primary air, and then mixed with the secondary air in the nozzle and blown into the fuming furnace; S32: The hot slag reacts with pulverized coal and air, and the dusty flue gas produced is recycled by the waste heat boiler, cooled by the surface cooler, and collected by the bag filter. The collected secondary zinc oxide dust is sent to the zinc system to recover valuable metals; S33: The flue gas after dust collection is sent to the ionic liquid for desulfurization, and the high-concentration SO2 is sent to the one-turn-one-absorption acid-making system. After acid making, the tail gas is further desulfurized and denitrified by the ionic liquid before it meets the emission standards.

2. A process for treating zinc leaching slag according to claim 1, characterized in that: In step 1, the heat source of the rotary drying drum is natural gas, and the drying temperature is 700-750°C.

3. A process for treating zinc leaching slag according to claim 1, characterized in that: The dust collected by the waste heat boiler and the buried scraper conveyor equipped with the electrostatic precipitator is sent to the lead smelting system in the factory to recover lead.

4. The process for treating zinc leaching slag according to claim 1, characterized in that: The slag produced by the fuming furnace can be sent to a slag dump for temporary storage and sale after water crushing and sedimentation.

5. A process for treating zinc leaching slag according to claim 1, characterized in that: The molten pool area of ​​the furnace body is an area surrounded by a first-layer copper water jacket assembly (3) and a second-layer copper water jacket assembly (4). A plurality of primary air inlets (2) are provided, which are symmetrically distributed on both sides of the first-layer copper water jacket assembly (3). The furnace body also includes a reburning area, which is an area surrounded by a third-layer copper water jacket assembly (5) and a fourth-layer steel water jacket assembly (6). Secondary air inlets (7) for introducing secondary air are installed on both sides of the third-layer copper water jacket assembly (5), where Pb, Zn, S, and CO in the furnace gas undergo an oxidation reaction with the blown air, and part of the heat released by the oxidation reaction is returned to the molten pool area.

6. A process for treating zinc leaching slag according to claim 5, characterized in that: In order to reduce the amount of fine furnace materials being carried away by furnace gas, the second-layer copper water jacket assembly (4) and the third-layer copper water jacket assembly (5) are tilted outwards, and the furnace width is increased to reduce the air flow speed and the smoke rate.

7. A process for treating zinc leaching slag according to claim 1, characterized in that: The furnace (9) is composed of refractory materials built in a steel trough welded with outer steel plates. The inner layer of the refractory material is built with magnesia-chrome bricks, and the outer layer is built with ordinary high-aluminum bricks. The bottom masonry of the furnace (9) is in an inverted arch shape, and insulation material is filled between the refractory material and the steel shell. In order to ensure heat exchange in the furnace (9), the furnace is built with a high and low furnace bottom, reducing the volume of the furnace to maintain the thermal balance of the furnace. A siphon slag discharge port is provided at the front end of the furnace (9), and the slag is continuously discharged during production.

8. The process for treating zinc leaching slag according to claim 1, characterized in that: The furnace roof is made of a box-type water jacket welded from steel plates, the inner surface of the furnace is provided with steel hooks to hang refractory materials, and the exhaust pipe (10) adopts a membrane-type water-cooled wall structure to reduce the amount of smoke and ensure that the melt does not enter the waste heat boiler.

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