CN215918601U

CN215918601U - Treatment system for waste cathode of aluminum electrolytic cell

Info

Publication number: CN215918601U
Application number: CN202122123963.9U
Authority: CN
Inventors: 辛鹏飞; 吴卫国
Original assignee: China ENFI Engineering Corp
Current assignee: China ENFI Engineering Corp
Priority date: 2021-09-03
Filing date: 2021-09-03
Publication date: 2022-03-01
Anticipated expiration: 2031-09-03

Abstract

The utility model provides a treatment system for waste cathodes of aluminum electrolysis cells. The processing system comprises: a molten pool smelting unit, a defluorination unit, a mixing granulation device and a waste heat recovery device. A molten pool, a feed inlet, an oxygen inlet, a dust-containing flue gas outlet, a metal outlet and a slag discharge port which are communicated with a flue gas area of the molten pool are arranged in the molten pool smelting unit; the defluorination unit is provided with a dust-containing flue gas inlet, the dust-containing flue gas inlet is communicated with a dust-containing flue gas outlet through a dust-containing flue gas conveying pipeline, the defluorination unit is used for removing fluorine element in the dust-containing flue gas, the mixing and granulating device is provided with a raw material inlet and a mixed granule outlet, and the mixed granule outlet is communicated with the charging hole; the waste heat recovery device is communicated with the dust-containing flue gas conveying pipeline and is used for recovering heat in the dust-containing flue gas. The method can realize the cooperative treatment of the waste cathode of the aluminum electrolytic cell and the industrial hazardous waste containing lead and zinc, ensure the stable thermal balance of the molten pool and improve the treatment capacity of the waste cathode.

Description

Treatment system for waste cathode of aluminum electrolytic cell

Technical Field

The utility model relates to the field of recovery of waste cathodes of aluminum electrolysis cells, in particular to a treatment system of waste cathodes of aluminum electrolysis cells.

Background

A large amount of waste cathodes are generated in the aluminum electrolysis process, and because electrolytes such as sodium fluoride and the like are infiltrated into the cathodes in the using process, the waste cathodes contain a large amount of fluoride, and NaCN and other substances can be generated in the cathodes in the using process. F in waste cathode leaching solution^-And CN^-The content exceeds the requirement of relevant discharge standard of national hazardous waste. In this standard, aluminum electrolysis solid waste is classified as HW32 inorganic fluoride waste, HW07 thermal treatment cyanide-containing waste, and HW33 inorganic cyanide waste.

The waste cathode comprises carbon and electrolyte, belongs to dangerous waste, and therefore, the waste cathode must be subjected to harmless treatment. The existing waste cathode treatment methods can be divided into four types: landfill method, physical separation, chemical leaching and high-temperature heat treatment. The physical separation method mainly comprises a flotation method; the chemical leaching method comprises an acid-base leaching method, an ultrasonic wave and pressure leaching method and the like. The high-temperature heat treatment method comprises a high-temperature hydrolysis method, a rotary kiln roasting treatment process and the like.

The flotation method is adopted to separate the waste cathode, so that the cost is low, but the process is long, and the material preparation process can generate secondary dust pollution. The chemical leaching method has the advantages of complex process flow, large investment and less industrial application at present.

The method comprises the steps of crushing the inner lining of the electrolytic cell, including a cathode carbon block and the like, adding a mixture of limestone and silicon dioxide into the crushed material, roasting the mixture in a rotary kiln at the roasting temperature of 650-1000 ℃, and enabling produced solid slag to meet the requirements of common solid wastes. Although the waste cathode is treated by rotary kiln calcination to achieve harmlessness, the produced slag is highly alkaline, which increases leachability of residual fluoride and cyanide. Meanwhile, the waste cathode is calcined by adopting a rotary kiln calcination method, and carbon in the waste cathode is only used as fuel, so that the strong reduction characteristic of the waste cathode cannot be fully exerted.

In view of the above problems, it is necessary to provide a new apparatus for detoxifying waste cathodes.

SUMMERY OF THE UTILITY MODEL

The utility model mainly aims to provide a treatment system for waste cathodes of an aluminum electrolysis cell, which aims to solve the problems of low recovery rate and complex process flow of the existing treatment method for waste cathodes of aluminum electrolysis.

In order to achieve the above object, one aspect of the present invention provides a system for treating waste cathodes in an aluminum electrolysis cell, including: a molten pool smelting unit, a defluorination unit, a mixing granulation device and a waste heat recovery device. A molten pool, a feed inlet, an oxygen inlet, a dust-containing flue gas outlet, a metal outlet and a slag discharge port which are communicated with a flue gas area of the molten pool are arranged in the molten pool smelting unit; the defluorination unit is provided with a dust-containing flue gas inlet, the dust-containing flue gas inlet is communicated with the dust-containing flue gas outlet through a dust-containing flue gas conveying pipeline, and the defluorination unit is used for removing fluorine elements in the dust-containing flue gas; the mixing and granulating device is provided with a raw material inlet and a mixed granule outlet, and the mixed granule outlet is communicated with a charging hole; the waste heat recovery device is communicated with the dust-containing flue gas conveying pipeline and is used for recovering heat in the dust-containing flue gas.

Further, the molten bath smelting unit comprises: the device comprises a molten bath smelting device, at least one spray gun, an oxygen supply device and an oxygen flow control device. The molten pool smelting device is provided with a feed inlet, an oxygen inlet, a dust-containing flue gas outlet, a metal outlet and a slag discharge port; each spray gun is immersed below the liquid level of the molten pool and sprays oxygen into the molten pool; the oxygen supply device is used for supplying oxygen to each spray gun; the oxygen flow control device is used for controlling the flow of oxygen in each spray gun.

Further, the molten bath smelting unit comprises: the device comprises a molten pool smelting device, at least one spray gun, an oxygen supply device, a nitrogen supply device and a gas composition adjusting device, wherein the molten pool smelting device is provided with a feed inlet, an oxygen inlet, a dust-containing flue gas outlet, a metal outlet and a slag discharge port; each spray gun is immersed below the liquid level of the molten pool and sprays oxygen into the molten pool; the oxygen supply device is used for supplying oxygen to each spray gun; the nitrogen supply device is used for supplying nitrogen to each spray gun; the gas composition adjusting device is respectively electrically connected with the oxygen supply device and the nitrogen supply device so as to control the content of the oxygen sprayed by each spray gun.

Furthermore, the included angle between each spray gun and the liquid level in the molten pool is-15-90 degrees.

Further, each lance is arranged at the side or bottom of the molten bath smelting unit.

Further, the defluorination unit comprises a dry defluorination device, the dry defluorination device is provided with a defluorination agent inlet, a dust-containing flue gas inlet, a first defluorination flue gas outlet and a first defluorination smoke dust outlet, and the dust flue gas inlet is communicated with the dust-containing flue gas outlet through a dust-containing flue gas conveying pipeline.

Further, the defluorination unit further comprises an electric dust removal device which is arranged on a dust-containing flue gas conveying pipeline between the waste heat recovery device and the dust-containing flue gas inlet, and the electric dust removal device is provided with a second defluorination flue gas outlet and a second defluorination smoke dust outlet.

Further, the treatment system of the waste cathode of the aluminum electrolytic cell further comprises a flue gas purification device, wherein the flue gas purification device is provided with a desulfurizer inlet and a gas inlet to be purified, and the gas inlet to be purified is communicated with the first defluorinated flue gas outlet and is used for desulfurizing the first defluorinated flue gas.

By applying the technical scheme provided by the utility model, the waste cathode of the aluminum electrolytic cell is treated by adopting the method provided by the utility model, the combustion heat release property and the reducibility of carbon in the waste cathode can be simultaneously utilized, and the cooperative treatment of industrial hazardous waste containing lead and zinc is realized. The reaction generated by industrial hazardous waste in the treatment process can consume the heat generated by burning the waste cathode, so that the heat balance of a molten pool is stable when a large amount of waste cathodes are treated, overheating is avoided, and the treatment capacity of the waste cathodes is improved. In addition, the process flow is shortened, and the environmental protection of the treatment system is improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the utility model and, together with the description, serve to explain the utility model and not to limit the utility model. In the drawings:

fig. 1 shows a schematic configuration of a system for treating spent cathodes according to an exemplary embodiment of the present invention;

fig. 2 is a schematic diagram illustrating a waste cathode treatment system according to a preferred embodiment of the present invention;

fig. 3 shows a process flow diagram of a method for treating a waste cathode provided in embodiment 1 of the present invention.

Wherein the figures include the following reference numerals:

10. a molten bath smelting unit; 11. a molten bath smelting device; 101. a feed inlet; 102. a dust-containing flue gas outlet; 12. a spray gun; 13. an oxygen supply device; 14. an oxygen flow control device; 15. a nitrogen gas supply device; 16. a gas composition adjusting device; 17. a water supply device; 18. a calcium-containing flux supply device;

20. a defluorination unit; 201. a dusty flue gas inlet; 21. a dry defluorination apparatus; 22. an electric dust removal device;

30. a mixing and granulating device; 301. a mixed pellet outlet; 40. a waste heat recovery device; 50. a flue gas purification device.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As described in the background art, the existing aluminum electrolysis waste cathode treatment method has the defects of low recovery rate and complex process flow. In view of the above-described technical problems, an exemplary embodiment of the present application provides a processing system for waste cathodes of aluminum reduction cells, as shown in fig. 1 and 2, comprising: a molten bath smelting unit 10, a defluorination unit 20, a mixing granulation device 30 and a waste heat recovery device 40. A molten pool, a feed inlet 101 communicated with a flue gas area of the molten pool, an oxygen inlet, a dust-containing flue gas outlet 102, a metal outlet and a slag discharge port are arranged in the molten pool smelting unit 10; the defluorination unit 20 is provided with a dust-containing flue gas inlet 201, the dust-containing flue gas inlet 201 is communicated with the dust-containing flue gas outlet 102 through a dust-containing flue gas conveying pipeline, and the defluorination unit 20 is used for removing fluorine elements in the dust-containing flue gas; the mixing and granulating device 30 is provided with a raw material inlet and a mixed granule outlet 301, and the mixed granule outlet 301 is communicated with the feed inlet 101; the waste heat recovery device 40 is communicated with the conveying pipeline of the dust-containing flue gas and is used for recovering heat in the dust-containing flue gas.

In the molten bath smelting unit 10, the feed inlet 101 is used for adding the aluminum electrolysis cell waste cathode and the lead-zinc-containing material, the lead-zinc-containing material (for example, lead-zinc-containing industrial hazardous waste or lead-zinc-containing industrial hazardous waste) is melted to form a melt, and carbon in the aluminum electrolysis cell waste cathode is completely combusted in the molten bath, so that more heat is provided for smelting; cyanide in the waste cathode is decomposed by smelting, so that harmless treatment is realized; meanwhile, fluoride in the waste cathode is decomposed to form fluorine-containing flue gas which enters the flue gas. And then, reducing the oxygen introduction amount, carrying out incomplete combustion on carbon in the waste cathode in a molten pool to form a reducing atmosphere, reducing lead elements and zinc elements in the lead-zinc-copper-containing material into partial simple substance lead steam and simple substance zinc steam in the reducing atmosphere, and then introducing the partial simple substance lead steam and the partial simple substance zinc steam into flue gas to carry out oxidation reaction to obtain the smoke dust containing lead oxide and zinc oxide. And finally, removing fluorine elements in the dust-containing flue gas in a defluorination device to obtain the defluorinated flue gas, thereby improving the environmental protection of the whole aluminum electrolysis cell waste cathode treatment system. Before smelting, the reaction raw materials are granulated in the mixing and granulating device 30, so that the dust pollution caused by the raw material powder in the smelting process can be avoided, and the waste cathode of the aluminum electrolytic cell and the lead-zinc-containing material can be ensured to be smelted in a synergistic manner according to a specific proportion in the smelting process. The waste heat recovery device 40 is communicated with the conveying pipeline of the dust-containing flue gas and is used for recovering heat in the dust-containing flue gas.

In conclusion, the treatment device provided by the application is used for treating the waste cathode of the aluminum electrolytic cell, so that the combustion heat release property and the reducibility of carbon in the waste cathode can be simultaneously utilized, and the cooperative treatment of the lead-zinc-containing industrial hazardous waste is realized. The reaction generated by industrial hazardous waste in the treatment process can consume the heat generated by burning the waste cathode, so that the heat balance of a molten pool is stable when a large amount of waste cathodes are treated, overheating is avoided, and the treatment capacity of the waste cathodes is improved; in addition, the process flow is shortened, and the environmental protection of the treatment system is improved.

In a preferred embodiment, as shown in fig. 1, the system for treating the waste cathode of the aluminum reduction cell further comprises: a bath smelting unit 11, at least one lance 12, an oxygen supply 13 and an oxygen flow control device 14. The molten pool smelting device 11 is provided with the feeding port 101, an oxygen inlet, a dust-containing flue gas outlet 102, a metal outlet and a slag discharge port; each spray gun 12 is immersed below the liquid level of the molten pool and sprays oxygen into the molten pool; an oxygen supply device 13 for supplying oxygen to each lance 12; an oxygen flow control device 14 is used to control the flow of oxygen to each lance 12. Blowing oxygen into the lance 12 at a specific angle below the surface of the melt can cause strong agitation of the melt produced during the melting process, which is advantageous in further improving the melting effect and the slag discharge efficiency. The flow of oxygen is controlled by an oxygen flow control device 14 to control the reaction atmosphere in the molten bath smelting unit 11.

In another preferred embodiment, as shown in fig. 2, the system for treating the waste cathode of the aluminum reduction cell further comprises: a bath smelting unit 11, at least one lance 12, an oxygen supply 13, a nitrogen supply 15 and a gas composition regulating unit 16. The molten pool smelting device 11 is provided with the feeding port 101, an oxygen inlet, a dust-containing flue gas outlet 102, a metal outlet and a slag discharge port; each spray gun 12 is immersed below the liquid level of the molten pool and sprays oxygen into the molten pool; an oxygen supply device 13 for supplying oxygen to each lance 12; a nitrogen gas supply device 15 for supplying nitrogen gas into each lance 12; the gas composition adjusting device 16 is electrically connected to the oxygen supply device 13 and the nitrogen supply device 15, respectively, to control the amount of oxygen sprayed from each lance 12. Blowing oxygen into the lance 12 at a specific angle below the surface of the melt can cause strong agitation of the melt produced during the melting process, which is advantageous in further improving the melting effect and the slag discharge efficiency. The nitrogen gas supply device 15 and the gas composition adjusting device 16 are arranged to control the introduction amount of oxygen gas, and thus the reaction atmosphere in the molten bath smelting device 11.

In a preferred embodiment, each lance 12 is angled at-15 to 90 degrees relative to the liquid surface in the molten bath. Limiting the angle between each lance 12 and the liquid level in the bath within the above ranges facilitates increasing the extent and depth of agitation of the bath smelting unit 11 by the lance 12, thereby further increasing smelting efficiency.

In a preferred embodiment, each lance 12 is positioned at the side or bottom of the molten bath melting apparatus 11. Compared with the spray gun 12 arranged at the top of the molten pool smelting device 11, the spray gun 12 arranged at the side part and the bottom of the molten pool smelting device 11 can carry out deeper reduction smelting process, thereby being beneficial to further improving the recovery rate of metal elements and the treatment efficiency of the waste cathode of the aluminum electrolytic cell.

The above defluorination unit 20 may be any device commonly used in the art to achieve the function of removing fluorine elements from flue gas, and the structure thereof is not particularly limited. In a preferred embodiment, as shown in fig. 2 and 3, the defluorination unit 20 comprises a dry defluorination apparatus 21, the dry defluorination apparatus 21 is provided with a defluorination agent inlet, a dusty flue gas inlet 201, a first defluorination flue gas outlet and a first defluorination flue gas outlet, and the dusty flue gas inlet 201 is communicated with the dusty flue gas outlet 102 through a dusty flue gas conveying pipeline. In the dry defluorination device 21, the fluorine-containing flue gas and the lead-zinc-containing smoke dust can react with the defluorination agent, so that the deep defluorination process can be realized, and the tail gas purification degree can be further improved.

In order to further improve the defluorination efficiency, as shown in figures 1 and 2, the dust content in the defluorinated flue gas is reduced at the same time. Preferably, the defluorination unit 20 further comprises an electric dust removal device 22, the electric dust removal device 22 is arranged on the dust-laden flue gas conveying pipeline between the waste heat recovery device 40 and the dust-laden flue gas inlet 201, and the electric dust removal device 22 is provided with a second defluorination flue gas outlet and a second defluorination flue gas outlet.

In order to further improve the environmental protection of the defluorinated flue gas, preferably, as shown in fig. 1 and 2, the treatment system of the waste cathode of the aluminum electrolysis cell further comprises a flue gas purification device 50, wherein the flue gas purification device 50 is provided with a desulfurizer inlet and a gas inlet to be purified, and the gas inlet to be purified is communicated with the first defluorinated flue gas outlet and is used for desulfurizing the first defluorinated flue gas.

In a preferred embodiment, as shown in fig. 1 and 2, the system for treating the waste cathode of the aluminum reduction cell further comprises a water supply device 17, wherein the water supply device 17 is provided with a water supply port, and the water supply port is communicated with the feeding port 101 and is used for adding water into the molten bath smelting device 11. The addition of a quantity of water to the bath smelting unit 11 enables it to form water gas, which contributes to further improving the efficiency of the reduction smelting.

In a preferred embodiment, as shown in fig. 1 and 2, the above-mentioned treatment system for the waste cathode of the aluminum reduction cell further comprises a calcium-containing flux supply device 18, the calcium-containing flux supply device 18 being provided with a calcium-containing flux supply port, the calcium-containing flux supply port being in communication with the feed port 101 for feeding calcium-containing flux to the bath smelting device 11. The calcium-containing flux can greatly reduce the smelting temperature, and simultaneously, the calcium-containing flux can form undecomposed residual fluoride or other impurities into insoluble matters, thereby improving the defluorination efficiency and improving the purity of lead metal.

Another aspect of the present application also provides a method for treating a waste cathode of an aluminum electrolysis cell, as shown in fig. 3, where the waste cathode of the aluminum electrolysis cell contains carbon and fluoride, and the method for treating the waste cathode of the aluminum electrolysis cell includes: sequentially melting and reducing and smelting a mixture of the waste cathode of the aluminum electrolytic cell and a lead-zinc-containing material and oxygen to obtain lead metal, furnace slag and dust-containing flue gas, wherein the dust-containing flue gas comprises flue dust containing lead oxide and zinc oxide and fluorine-containing flue gas; removing fluorine elements in the dust-containing flue gas to obtain defluorinated flue gas; wherein the weight ratio of the waste cathode of the aluminum electrolytic cell to the lead and zinc in the lead and zinc-containing material is (8 to E)35) 10-60 ℃, the temperature of the melting process and the reduction melting process is 1100-1350 ℃, and the introduction amount of oxygen in the melting process is 80-100 Nm³The oxygen introduction amount in the reduction smelting process is 12.5-30 Nm per ton of mixture³Per ton of mixture.

During the smelting process of the molten pool, lead-zinc-containing materials (such as lead-zinc-containing industrial hazardous wastes or lead-zinc-containing industrial hazardous wastes) are melted to form a melt, and carbon in the waste cathode of the aluminum electrolysis cell is completely combusted in the molten pool, so that more heat is provided for smelting; cyanide in the waste cathode is smelted and decomposed, so that harmless treatment is realized; meanwhile, fluoride in the waste cathode is decomposed to form fluorine-containing flue gas which enters the flue gas. And then, by reducing the introduction amount of oxygen, carbon in the waste cathode is incompletely combusted in a molten pool to form a reducing atmosphere, lead elements and zinc elements in the lead-zinc-copper-containing material are reduced into partial simple substance lead and simple substance zinc in the reducing atmosphere, and then the lead elements and the zinc elements enter flue gas and are subjected to oxidation reaction to obtain the smoke containing lead oxide and zinc oxide. And simultaneously removing fluorine elements in the dust-containing flue gas to obtain defluorinated flue gas. The weight ratio of the waste cathode of the aluminum electrolytic cell to lead and zinc in the lead and zinc-containing material, the reduction temperature, the oxygen introduction amount in the melting process and the oxygen introduction amount in the reduction process are limited in the above range, which is beneficial to further improving the treatment efficiency of the waste cathode.

In conclusion, the method provided by the application is used for treating the waste cathode of the aluminum electrolytic cell, so that the combustion heat release property and the reducibility of carbon in the waste cathode can be simultaneously utilized, and the cooperative treatment of industrial hazardous wastes containing lead and zinc is realized. The reaction generated by industrial hazardous waste in the treatment process can consume the heat generated by burning the waste cathode, so that the heat balance of a molten pool is stable when a large amount of waste cathodes are treated, overheating is avoided, and the treatment capacity of the waste cathodes is improved.

In a preferred embodiment, in the smelting process, when oxygen is directly introduced, the oxygen content can be controlled by adjusting the introduced amount of the oxygen; when introducing a mixed gas of oxygen and other inert atmosphere (such as nitrogen), the smelting atmosphere can be controlled by adjusting the weight ratio of the oxygen to the nitrogen.

In the treatment method provided by the application, the fluorine element in the fluorine-containing flue gas can be removed by adopting a method commonly used in the field. In a preferred embodiment, the process for removing fluorine element from the dust-containing flue gas comprises the following steps: reacting fluorine-containing flue gas in the dust-containing flue gas with lead-zinc-containing smoke dust at 150-200 ℃ to obtain primary defluorinated flue gas and smoke dust containing lead fluoride and zinc fluoride; and reacting the primary defluorinated flue gas with a defluorinating agent to obtain the defluorinated flue gas. In the removing method, the fluorine-containing flue gas and the lead-zinc-containing smoke dust are firstly reacted to realize primary defluorination, and then the primary defluorination flue gas obtained by the primary defluorination step is reacted with the defluorination agent, so that the defluorination process can be realized to a greater extent. Therefore, by adopting the two-stage defluorination treatment, the removal rate of the fluorine element can be improved, and the environmental protection of the treatment method can be improved.

Preferably, the preliminary defluorination process is carried out in an electric precipitation plant. After the fluorine-containing flue gas reacts with the lead-zinc-containing flue dust, the obtained lead fluoride and zinc fluoride-containing flue dust can remove fluorine elements and primary defluorinated flue gas in an electric dust removal device. The fluorine removing agent used in the second defluorination process may be of the kind commonly used in the art. Preferably, the fluorine removal agent includes, but is not limited to, one or more of the group consisting of alumina, calcium oxide and silica. The fluorine removal agents are low in price and better in combination property with fluorine elements, so that the fluorine removal agents are selected to be favorable for further improving the fluorine removal effect and reducing the process cost.

In the treatment process, carbon in the waste cathode is used as a reducing agent to reduce metal elements in the lead-zinc-copper-containing material, so that in order to further improve the synergistic smelting effect of the waste cathode of the aluminum electrolytic cell and the lead-zinc-copper-containing material, preferably, the weight ratio of the lead to zinc in the waste cathode of the aluminum electrolytic cell to the lead-zinc-copper-containing material is (15-20): (50-60); the temperature of the melting process and the reduction melting process is 1150-1250 ℃. Optionally, the weight ratio of the waste cathode of the aluminum electrolytic cell to the lead and zinc in the lead-zinc-copper-containing material is 8:51, 8:58, 12:51, 15:50, 20:60 or 35: 10; is meltedThe temperature of the process and the reduction smelting process is 1100 ℃, 1150 ℃, 1250 ℃ or 1350 ℃; the oxygen was introduced in an amount of 80Nm during the melting³90Nm per ton of mixture³Per ton of mixture or 100Nm³The oxygen is introduced into the mixture per ton in the reduction smelting process in an amount of 12.5Nm³20Nm per ton of mixture ³30 Nm/ton of mixture³Per ton of mixture.

In a preferred embodiment, the method for treating the waste cathode of the aluminum electrolysis cell further comprises the following steps: and adding a calcium-containing flux in the reduction smelting process, so that the calcium-containing flux and the undecomposed residual fluoride are subjected to a curing reaction to obtain calcium fluoride. The addition of the calcium-containing flux can greatly reduce the smelting temperature, and meanwhile, the calcium-containing flux can form undecomposed residual fluoride or other impurities into insoluble matters, so that the defluorination efficiency is reduced, and the purity of lead metal is improved. Optionally, the calcium-containing flux is added in an amount of 1, 5, 8, 10, 15, 20 wt% based on the total weight of the spent cathode of the aluminum electrolysis cell, the lead-zinc containing material and the calcium-containing flux. Preferably, the calcium-containing flux includes, but is not limited to, one or more of the group consisting of limestone, calcium oxide and calcium carbonate; based on the total weight of the waste cathode of the aluminum electrolytic cell, the lead-zinc containing material and the calcium-containing flux, the addition amount of the calcium-containing flux is 8-20 wt%.

In a preferred embodiment, the melt is generated through a melting process and a reduction melting process, oxygen is blown into the melt below the liquid level by using at least one spray gun, and the included angle between each spray gun and the liquid level of the melt is-15-90 degrees. Blowing oxygen into the molten liquid below the liquid level of the molten liquid by a lance at a specific angle can generate strong agitation to the molten liquid generated in the smelting process, which is beneficial to further improving the smelting effect and the slag discharge efficiency. The contact time of oxygen and the molten liquid can be adjusted by adjusting the included angle between the spray gun and the liquid level of the molten liquid, thereby being beneficial to improving the smelting effect. Alternatively, the angle between each lance and the liquid surface of the melt may be-15, 30 °, 45 °, 60 ° or 90 °.

In a preferred embodiment, the above-mentioned treatment method further comprises granulating the mixture before the melting process. Before smelting, the reaction raw materials are granulated, so that the dust pollution caused by raw material powder in the smelting process can be avoided, and the waste cathode of the aluminum electrolytic cell and the lead-zinc-containing material can be cooperatively smelted according to a specific proportion in the smelting process. More preferably, the granule size of the granule prepared in the granulating process is 5 mm-30 mm, and in the granule, the granule with the granule size of 8-20 mm accounts for more than 85% of the total weight of the granule, and the granule with the granule size of 20-30 mm accounts for less than or equal to 15% of the total weight of the granule. The raw materials are treated by adopting the granulating process, so that the environmental protection property of the process is further improved, the synergistic smelting effect of the two materials is further improved, and the smelting efficiency and the recovery rate of metal elements are improved.

In order to further improve the environmental protection of the defluorinated flue gas, preferably, the method for treating the waste cathode of the aluminum electrolysis cell further comprises the following steps: and carrying out desulfurization treatment on the defluorinated flue gas to obtain purified flue gas.

In a preferred embodiment, the lead-zinc containing material also contains copper, preferably, the weight percentage content of lead element in the lead-zinc containing material is less than or equal to 20 wt%, the weight percentage content of zinc element is less than or equal to 5 wt%, and the weight percentage content of copper element is less than or equal to 5 wt% based on the weight of the lead-zinc containing material.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the utility model as claimed.

Example 1

The composition of the spent graphite cathodes in the examples is shown in table 1.

TABLE 1

Composition (I)	C	Na₂O	Al₂O₃	CaO	F
						Content, wt%	55	15	11	1.23	11

The composition of the lead-zinc-copper hazardous waste is shown in table 2.

TABLE 2

Composition (I)	Pb	Zn	Cu	Fe	SiO₂
						Content, wt%	70	5	1	8	6

The process flow is shown in FIG. 1.

The method comprises the following steps of (1) carrying out primary crushing on waste graphite cathodes, flux (the type is CaO) and hazardous waste containing lead, zinc and copper according to the proportion of 10: 5:85 (wherein the weight ratio of the waste graphite cathode to the lead and the zinc in the lead-zinc-copper-containing hazardous waste is 8:51) to obtain a mixed material; then, granulation was performed. The particle size requirements are shown in table 3.

TABLE 3

Particle size	5mm～30mm	8～20mm	20～30mm
				Proportion%	100	＞85	≤15

Adding the mixed and granulated granules into a molten pool smelting device 11 (a side-blown molten pool smelting furnace), wherein the feeding amount is 50t/h, supplementing oxygen into a molten pool through an immersed oxygen lance, the angle between the oxygen lance and the liquid level of the molten pool is 90 degrees, the pressure is 0.3MPa, and the temperature of the molten pool is 1100 ℃; the carbon part in the waste cathode is used as fuel to provide heat for the reaction of the molten pool, and is also used as a reducing agent to provide reducing atmosphere for the molten pool. The molten pool reaction is divided into three operations of melting period, reduction period and slag discharging, and the oxygen blowing amount of the three stages is 4500Nm³/h，1500Nm³/h,1000Nm³H is used as the reference value. To obtainTo dusty fumes, high copper lead bullion metal alloys and slag.

Flue gas produced by a waste heat boiler enters an electric dust collection system, the outlet temperature of the electric dust collector is 180 ℃, ZnO, PbO in the flue gas and fluorine-containing flue gas react in the electric dust collection, 10-15% of fluorine in the flue gas is removed, and primary defluorinated flue gas and defluorinating agent (Al) are obtained₂O₃Excess) to obtain defluorinated flue gas; and finally, carrying out desulfurization treatment on the defluorinated flue gas to obtain the purified tail gas.

In the metal phase, the content of lead element is 95.0%, and the recovery rate is 97.0%.

Example 2

The differences from example 1 are: the included angle between the spray gun and the liquid level of the molten liquid is 60 degrees.

In the metal phase, the content of lead element is 97%, and the recovery rate is 98%.

Example 3

The differences from example 1 are: the included angle between the spray gun and the liquid level of the molten liquid is 45 degrees.

In the metal phase, the content of lead element is 97.1%, and the recovery rate is 98.6%.

Comparative example 1

The differences from example 1 are: the weight ratio of the waste cathode of the aluminum electrolytic cell to the lead and zinc in the lead and zinc containing material is 1:10, and the addition amount of the flux (CaO) is 5 wt% based on the total weight of the waste cathode of the aluminum electrolytic cell, the lead and zinc containing material and the solvent.

In the metal phase, the content of lead element was 93%, and the recovery rate was 90%.

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects: adopt the device that this application provided to be favorable to improving greatly the content and the rate of recovery of plumbous element in the metallic phase.

It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those described or illustrated herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A processing system of the waste cathode of an aluminum electrolysis cell is characterized by comprising:

the device comprises a molten pool smelting unit (10), wherein a molten pool, a feed inlet (101), an oxygen inlet, a dust-containing flue gas outlet (102), a metal outlet and a slag discharge port which are communicated with a flue gas area of the molten pool are arranged in the molten pool smelting unit (10);

the device comprises a defluorination unit (20), wherein the defluorination unit (20) is provided with a dust-containing flue gas inlet (201), the dust-containing flue gas inlet (201) is communicated with a dust-containing flue gas outlet (102) through a dust-containing flue gas conveying pipeline, and the defluorination unit (20) is used for removing fluorine elements in dust-containing flue gas;

a mixing and granulating device (30), wherein the mixing and granulating device (30) is provided with a raw material inlet and a mixed granule outlet (301), and the mixed granule outlet (301) is communicated with the feeding port (101);

the waste heat recovery device (40), waste heat recovery device (40) with dusty flue gas conveying line intercommunication for retrieve the heat in the dusty flue gas.

2. The system for the treatment of spent cathodes of aluminium reduction cells according to claim 1, wherein the molten bath smelting unit (10) comprises:

the molten pool smelting device (11), the molten pool smelting device (11) is provided with the feed inlet (101), the oxygen inlet, the dust-containing flue gas outlet (102), the metal outlet and the slag discharge port;

at least one lance (12), each lance (12) being submerged below the surface of the molten bath and injecting oxygen into the molten bath;

an oxygen supply device (13), the oxygen supply device (13) being configured to supply oxygen into each of the lances (12);

an oxygen flow control device (14), the oxygen flow control device (14) for controlling the flow of oxygen in each lance (12).

3. The system for the treatment of spent cathodes of aluminium reduction cells according to claim 1, wherein the molten bath smelting unit (10) comprises:

a nitrogen gas supply device (15), wherein the nitrogen gas supply device (15) is used for supplying nitrogen gas into each spray gun (12);

a gas composition adjusting device (16), wherein the gas composition adjusting device (16) is respectively electrically connected with the oxygen supply device (13) and the nitrogen supply device (15) to control the oxygen content sprayed by each spray gun (12).

4. The treatment system for the waste cathodes of the aluminum reduction cells according to claim 2 or 3, wherein the included angle between each spray gun (12) and the liquid level in the molten bath is-15 to 90 °.

5. The system for the treatment of spent cathodes of aluminium reduction cells according to claim 4, wherein each lance (12) is arranged at the side or at the bottom of the molten bath smelting unit (11).

6. The treatment system of spent cathodes of aluminum reduction cells according to claim 1, wherein the defluorination unit (20) comprises a dry defluorination apparatus (21), the dry defluorination apparatus (21) being provided with a defluorination agent inlet, the dusty flue gas inlet (201), a first defluorination flue gas outlet and a first defluorination fume outlet.

7. The processing system for the waste cathodes of the aluminum reduction cells according to claim 6, wherein the defluorination unit (20) further comprises an electric dust removal device (22), the dust-containing flue gas transmission pipeline is arranged between the waste heat recovery device (40) and the dust-containing flue gas inlet (201), and the electric dust removal device (22) is provided with a second defluorination flue gas outlet and a second defluorination smoke outlet.

8. The system for treating spent cathodes of aluminum reduction cells as recited in claim 7, further comprising a flue gas purification device (50), wherein the flue gas purification device (50) is provided with a desulfurizing agent inlet and a gas inlet to be purified, the gas inlet to be purified being communicated with the first defluorinated flue gas outlet for desulfurizing the first defluorinated flue gas.