CN110592386A

CN110592386A - Comprehensive recovery method for smelting soot of waste circuit board

Info

Publication number: CN110592386A
Application number: CN201910927169.4A
Authority: CN
Inventors: 刘勇; 吕建芳; 刘牡丹; 陈志强; 吕先谨; 马致远; 刘超
Original assignee: Guangdong Institute of Resources Comprehensive Utilization
Current assignee: Institute of Resource Utilization and Rare Earth Development of Guangdong Academy of Sciences
Priority date: 2019-09-27
Filing date: 2019-09-27
Publication date: 2019-12-20
Anticipated expiration: 2039-09-27
Also published as: CN110592386B

Abstract

The invention belongs to the technical field of solid waste treatment, and particularly discloses a comprehensive recovery method for smelting soot of a waste circuit board. The recovery method comprises the steps of firstly adding alkali into smelting soot for pressure leaching, converting metal bromide salt and chloride salt in the soot into hydroxide precipitate, converting bromine and chlorine into soluble NaBr and NaCl respectively to realize separation of bromine, chlorine and valuable metals, evaporating and crystallizing filtrate to obtain a crude salt product, reducing and roasting filter residue, recovering zinc in the slag through volatilization to obtain a high-purity zinc oxide product, and further heating and smelting the roasted sand to obtain metal ingots and harmless reduction slag. The comprehensive recovery method of the smelting soot of the waste circuit board can effectively recover bromine, chlorine and valuable metals in the smelting soot of the waste circuit board.

Description

Comprehensive recovery method for smelting soot of waste circuit board

Technical Field

The invention relates to the technical field of solid waste treatment, in particular to a comprehensive recovery method of smelting soot of a waste circuit board.

Background

With the rapid expansion and upgrading of electronic products, the accumulation of waste electrical appliances and electronic equipment is greatly increased. The worldwide electronic waste is produced in about 3500 ten thousand tons per year, and the total amount of electronic waste is also sharply increased at a rate of about 4% per year. The waste circuit board is about 3 percent of the total amount of electronic waste, the waste circuit board contains about 61 percent of metal and 21 percent of plastic, the metal mainly comprises basic metal such as aluminum, copper, iron, nickel, lead, tin, zinc and the like, noble metal such as gold, silver, rhodium, selenium and the like and rare metal, and the plastic mainly comprises glass fiber reinforced phenolic resin or epoxy resin and also contains a part of flame retardant. Therefore, the waste circuit board is a high-value dangerous solid waste with resource utilization and environmental hazard. If the abandoned circuit board can not be reasonably disposed, not only can precious resources be wasted, but also the ecological environment is greatly polluted.

At present, the general methods for treating the waste circuit boards mainly include hydrometallurgy, supercritical fluid, pyrolysis, microbiological, mechanical physical, and incineration techniques. The incineration technique is to put the waste printed circuit board into a high temperature furnace for burning to convert the organic components into CO₂And H₂The products such as O, glass fiber and metal are discharged as residue, and the metal is further smelted and recovered. The circuit board contains combustible components such as resinThe calorific value of the coal is equivalent to that of coal, and the coal can provide heat energy for smelting. Therefore, the incineration technology can fully utilize the components such as resin and the like in the waste circuit board, has the advantages of large treatment capacity, simple process and high recovery rate, and is an effective method for treating the waste circuit board. The circuit board can produce the smoke and dust in the incineration process, contains a large amount of brominated flame retardants in the circuit board, and most bromine transfers to the flue gas in the incineration process, and part metal in the circuit board also can volatilize and get into the flue gas under high temperature in addition, and the smoke and dust of production has been collected through dust collecting system and has been handled and has obtained smelting cigarette ash, also is called smelting cigarette ash. The content of bromine in the smelting soot can reach more than 20 percent, and the smelting soot contains heavy metals such as copper, lead, zinc, tin and the like and noble metals such as gold, silver, palladium, platinum and the like. Smelting soot is not only a dangerous solid waste, but also a precious metal resource, so a method for reasonably utilizing the smelting soot is to be found, valuable elements are recycled, and the harm to the environment is eliminated.

Disclosure of Invention

The invention mainly solves the technical problem of providing a comprehensive recovery method of waste circuit board smelting soot, which can effectively extract and separate bromine and chlorine in the smelting soot and recover valuable metals with high yield.

In order to solve the technical problems, the invention adopts the technical scheme that: a comprehensive recovery method of waste circuit board smelting soot comprises the following steps:

s1: mixing the smelting soot with NaOH and water, leaching in a high-pressure kettle under the condition of adding pressure, wherein the reaction temperature is 150-200 ℃, the liquid-solid ratio of a reaction system is (2-3) to 1, and then filtering to obtain filter residue and filtrate; the reaction pressure is related to the reaction temperature, the reaction temperature is high, the corresponding reaction pressure is also high, and when the temperature is 150-200 ℃, the pressure is in the range of 0.5-1.5 MPa;

s2: evaporating and crystallizing the filtrate to obtain a chlorine and bromine containing mixed salt;

s3: reducing and roasting the filter residue, wherein a reducing agent is coke and/or coal, the roasting temperature is 1000-1200 ℃, roasting is carried out to obtain roasted sand, and smoke dust generated in roasting is collected to obtain crude zinc oxide;

s4: and reducing and smelting the calcine, adding a reducing agent and an auxiliary agent into the calcine, wherein the reducing agent is coke, the auxiliary agent is quartz stone and/or limestone, reducing and smelting at 1300-1500 ℃, cooling, and separating to obtain a metal ingot and harmless reducing slag.

In a preferred embodiment, in step S1, the addition amount of NaOH is 20 to 30% of the weight of the smelting soot.

In a preferred embodiment, in step S2, the evaporation temperature is 90 to 120 ℃, and the chlorine and bromine-containing mixed salt is a mixture of NaCl and NaBr, wherein the total mass percent of NaCl and NaBr is greater than or equal to 95%.

In a preferred embodiment, in step S3, the amount of the reducing agent added is 5-10% of the weight of the filter residue.

In a preferred embodiment, in step S4, the reducing agent is added in an amount of 15 to 20% by weight of the calcine, and the auxiliary agent is added in an amount of 20 to 40% by weight of the calcine.

Wherein the metal ingot is Cu-Pb-Sn alloy.

According to the comprehensive recovery method of the smelting soot of the waste circuit board, the treated smelting soot is a solid product obtained by collecting dust in the incineration process of the waste circuit board, wherein the solid product mainly contains Cu, Pb, Zn, Sn, Br, Cl and other elements, and the Br content is 20-30%. Firstly, adding alkali into smelting soot for pressure leaching, converting metal bromide salt and chloride salt in the soot into hydroxide precipitate by pressurization in the presence of strong alkali, and respectively converting bromine and chlorine into soluble NaBr and NaCl to realize the separation of bromine, chlorine and valuable metals; filtering after leaching, wherein the filtrate obtained by filtering is a solution containing NaBr and NaCl, and a mixed salt of NaCl and NaBr is obtained by evaporation and crystallization, wherein the total mass percent of NaCl and NaBr in the mixed salt is more than or equal to 95 percent, and the mixed salt can be directly sold as a raw material for preparing bromine water; at the moment, metals such as copper, lead, zinc, tin and the like are mainly enriched in filter residues, zinc in the filter residues is independently volatilized and separated by a method of adding a reducing agent for high-temperature volatilization, so that crude zinc oxide powder with a high added value is prepared, the purity of the crude zinc oxide is more than 90%, the roasting temperature is controlled to be below the melting point of the residues, so that the volatilization of copper, lead, tin and the like is reduced, the purity of zinc products is improved, the roasting temperature is generally controlled to be 1000-1200 ℃, carbon in the ash can also be used as the reducing agent, and the using amount of the reducing agent is reduced; and then, further smelting the roasted product calcine, limestone, quartz stone and a reducing agent together to recover metals such as copper, lead, tin and the like, wherein the limestone and the quartz stone can improve the properties of molten slag, and further heating and smelting are carried out to obtain a metal ingot and reducing slag, wherein the metal ingot mainly contains copper, lead and tin and is Cu-Pb-Sn alloy, the reducing slag contains low content of copper, lead, zinc and tin, the content of copper, lead, zinc and tin is less than 0.2 percent and is harmless slag, and the reducing slag can be used as a raw material for manufacturing cement.

The invention has the advantages that: the method can separate valuable metals from bromine and chlorine in the smelting soot, the bromine and the chlorine are prepared into mixed crude salt which can be used for producing bromine water, and zinc is separated from copper, lead and tin at the same time, so that the added value of products is further improved; the carbon in the ash is used as a smelting reducing agent, the production cost is reduced, the metal content in the finally produced reducing slag is less than 0.2%, the main component of the reducing slag is calcium silicate, and the reducing slag can be used for manufacturing cement.

Drawings

FIG. 1 is a process flow chart of the comprehensive recovery method of smelting soot from waste circuit boards provided by the invention.

Detailed Description

The technical solution of the present invention will be described in detail by specific examples.

In the following examples, the agents used are all commercially available. The concentrations or contents in the respective examples are mass percentages.

Example 1

The comprehensive recovery method of the waste circuit board smelting soot shown in FIG. 1 is adopted to treat the waste circuit board smelting soot, and comprises the following steps:

500g of smelting soot was collected and analyzed as shown in Table 1.

TABLE 1

Mixing the smelting soot with 100g of NaOH, adding water to adjust the liquid-solid ratio of a reaction system to be 2:1, adding the reaction mixed solution into an autoclave, setting the rotating speed to be 300rpm, and reacting for 2 hours at 150 ℃. After the reaction, the slurry was filtered to obtain 254.9g of residue and 933.4mL of filtrate.

200mL of the filtrate was taken, evaporated and crystallized at 100-105 ℃ until dryness to obtain 51.3g of mixed salt of NaCl and NaBr.

And (3) adding 5g of coke into 100g of filter residue, reducing and roasting at 1100 ℃ until no obvious smoke is generated, collecting the generated smoke to obtain 44.1g of crude zinc oxide, and roasting to obtain roasted sand.

And performing reduction smelting on the calcined sand, adding 7.5g of coke, 7.5g of limestone and 7.5g of quartz stone into 50g of calcined sand, performing reduction smelting at 1500 ℃ for 1h, cooling, and cooling to obtain 23.9g of metal ingot and 38.7g of harmless reduction slag. The smelting metal and reducing slag are layered, the slag is on the upper layer, the metal is on the lower layer, and the two are separated, which belongs to the prior art.

According to the detection, the total mass percent of NaCl and NaBr in the NaCl and NaBr mixed salt is 95.4%, and the bromine removal rate in the smelting soot is 90.1%. The contents of copper, lead, zinc and tin in the reducing slag are respectively 0.13%, 0.12%, 0.06% and 0.02%, the purity of crude zinc oxide is 92.4%, the recovery rate of zinc in smelting soot is 94.8%, the contents of copper, lead and tin in the metal ingot are respectively 46.9%, 24.1% and 12.4%, and the total recovery rate of copper, lead and tin is 95.3%.

Example 2

500g of smelting soot was collected and analyzed as shown in Table 1.

Mixing the smelting soot with 150g of NaOH, adding water to adjust the liquid-solid ratio of a reaction system to be 3:1, adding the reaction mixed solution into an autoclave, setting the rotating speed to be 300rpm, and reacting for 2 hours at 180 ℃. After the reaction, the slurry was filtered to obtain 248.4g of residue and 1443.2mL of filtrate.

200mL of the filtrate was taken, evaporated and crystallized at 115 ℃ and 120 ℃ until dryness to obtain 36.6g of mixed salt of NaCl and NaBr.

And (3) adding 8g of coke into 100g of filter residue, reducing and roasting at 1200 ℃ until no obvious smoke is generated, collecting the generated smoke to obtain 44.9g of crude zinc oxide, and roasting to obtain roasted sand.

And (3) carrying out reduction smelting on the calcined sand, adding 10g of coke, 7.5g of limestone and 7.5g of quartz stone into 50g of calcined sand, then carrying out reduction smelting at 1300 ℃ for 3h, cooling, and cooling to obtain 23.7g of metal ingot and 40.6g of harmless reduction slag.

According to the detection, the total mass percent of NaCl and NaBr in the NaCl and NaBr mixed salt is 96.3%, and the bromine removal rate in the smelting soot is 93.5%. The contents of copper, lead, zinc and tin in the reducing slag are respectively 0.17%, 0.13%, 0.07% and 0.02%, the purity of crude zinc oxide is 91.7%, the recovery rate of zinc in smelting soot is 93.3%, the contents of copper, lead and tin in a metal ingot are respectively 48.3%, 24.8% and 12.7%, and the total recovery rate of copper, lead and tin is 94.8%.

Example 3

500g of smelting soot was collected and analyzed as shown in Table 2.

TABLE 2

Mixing the smelting soot with 120g of NaOH, adding water to adjust the liquid-solid ratio of a reaction system to be 2.5:1, adding the reaction mixed solution into an autoclave, setting the rotating speed to be 300rpm, and reacting for 2 hours at 200 ℃. After the reaction, the slurry was filtered to obtain 278.3g of residue and 1213.4mL of filtrate.

Taking 200mL of filtrate, evaporating and crystallizing at the evaporation temperature of 95-100 ℃, and evaporating until dryness to obtain 30.8g of mixed salt of NaCl and NaBr.

And (3) adding 10g of coke into 100g of filter residue, reducing and roasting at 1000 ℃ until no obvious smoke is generated, collecting the generated smoke to obtain 47.0g of crude zinc oxide, and roasting to obtain roasted sand.

And (3) carrying out reduction smelting on the calcined sand, adding 9g of coke, 7.5g of limestone and 7.5g of quartz stone into 50g of calcined sand, then carrying out reduction smelting at 1400 ℃ for 1.5h, cooling, and cooling to obtain 26.4g of metal ingot and 34.2g of harmless reduction slag.

According to the detection, the total mass percent of NaCl and NaBr in the NaCl and NaBr mixed salt is 96.1%, and the bromine removal rate in the smelting soot is 90.7%. The contents of copper, lead, zinc and tin in the reducing slag are respectively 0.18%, 0.14%, 0.07% and 0.03%, the purity of crude zinc oxide is 92.5%, the recovery rate of zinc in smelting soot is 95.7%, the contents of copper, lead and tin in a metal ingot are respectively 52.4%, 21.3% and 13.7%, and the total recovery rate of copper, lead and tin is 96.3%.

Example 4

500g of smelting soot was collected and analyzed as shown in Table 2.

Mixing the smelting soot with 120g of NaOH, adding water to adjust the liquid-solid ratio of a reaction system to be 3:1, adding the reaction mixed solution into an autoclave, setting the rotating speed to be 300rpm, and reacting for 3 hours at 160 ℃. After the reaction, the slurry was filtered to obtain 281.6g of residue and 1467.9mL of filtrate.

200mL of the filtrate was taken, evaporated and crystallized at 105-110 ℃ until dryness to obtain 31.7g of mixed salt of NaCl and NaBr.

And (3) adding 8g of coke into 100g of filter residue, reducing and roasting at 1200 ℃ until no obvious smoke is generated, collecting the generated smoke to obtain 44.2g of crude zinc oxide, and roasting to obtain roasted sand.

And (3) carrying out reduction smelting on the calcined sand, adding 7.5g of coke, 7.5g of limestone and 7.5g of quartz stone into 50g of calcined sand, then carrying out reduction smelting for 2h at 1400 ℃, cooling, and cooling to obtain 27.2g of metal ingot and 33.8g of harmless reduction slag.

According to the detection, the total mass percent of NaCl and NaBr in the NaCl and NaBr mixed salt is 95.9%, and the bromine removal rate in the smelting soot is 89.9%. The contents of copper, lead, zinc and tin in the reducing slag are respectively 0.17%, 0.11%, 0.07% and 0.03%, the purity of crude zinc oxide is 90.2%, the recovery rate of zinc in smelting soot is 92.8%, the contents of copper, lead and tin in a metal ingot are respectively 49.1%, 20.0% and 12.8%, and the total recovery rate of copper, lead and tin is 94.1%.

The above examples illustrate that the recovery method provided by the present invention can effectively recover bromine, chlorine and valuable metals in the smelted aluminum ash, and finally obtain harmless reducing slag after treatment.

Claims

1. A comprehensive recovery method of waste circuit board smelting soot is characterized by comprising the following steps:

s1: mixing the smelting soot with NaOH and water, leaching in a high-pressure kettle under the condition of adding pressure, wherein the reaction temperature is 150-200 ℃, the liquid-solid ratio of a reaction system is (2-3) to 1, and then filtering to obtain filter residue and filtrate;

2. The comprehensive recycling method of smelting soot of waste circuit boards as claimed in claim 1, wherein in step S1, the amount of NaOH added is 20-30% of the weight of the smelting soot.

3. The comprehensive recycling method of smelting soot from waste circuit boards as claimed in claim 2, wherein in step S2, the evaporation temperature is 90-120 ℃, and the chlorine and bromine-containing mixed salt is a mixture of NaCl and NaBr, wherein the total mass percent of NaCl and NaBr is greater than or equal to 95%.

4. The comprehensive recycling method of the smelting soot of the waste circuit board as claimed in claim 3, wherein in the step S3, the adding amount of the reducing agent is 5-10% of the weight of the filter residue.

5. The comprehensive recycling method of smelting soot from waste circuit boards as claimed in claim 4, wherein in step S4, the addition amount of the reducing agent is 15-20% of the weight of the calcine, and the addition amount of the auxiliary agent is 20-40% of the weight of the calcine.

6. The comprehensive recycling method of smelting soot from waste circuit boards as recited in claim 5, wherein the metal ingot is Cu-Pb-Sn alloy.