阅读说明：本技术 富氧侧吹炉熔炼处理废旧电路板的方法 (Method for smelting waste circuit board by oxygen-enriched side-blown furnace ) 是由 邹小平 王海北 蒋开喜 章小兵 张驰 刘三平 薛宇飞 *** 余忠珠 蒋应平 黄 于 2020-07-06 设计创作，主要内容包括：富氧侧吹炉熔炼处理废旧电路板的方法,属于废旧电路板火法处理技术领域。包括以下步骤：(1)将废电路板破碎；(2)将电路板碎料与辅料配料；(3)将步骤(2)所得混合炉料送入侧吹炉中富氧熔炼,得到高温熔体及高温烟气；(4)将高温熔体送入电炉沉降分离,分别从放铜口和放渣口放出粗铜和炉渣；(5)将高温烟气送入燃烧室燃烧,然后送入余热锅炉回收余热及部分收尘,经骤冷塔降温后送入布袋收尘装置捕集熔炼烟尘,由排风机送入二次喷淋塔喷淋处理,最后经电除雾器处理后排空。本发明造锍过程迅速,可以较好捕集废电路板中的贵金属,充分回收资源,有效防止和减少二噁英的生成,具有处理效率高、成本低和环保性好的优点。(A method for smelting and processing a waste circuit board by an oxygen-enriched side-blown furnace belongs to the technical field of fire processing of waste circuit boards. The method comprises the following steps: (1) crushing the waste circuit board; (2) mixing the circuit board crushed aggregates with auxiliary materials; (3) feeding the mixed furnace burden obtained in the step (2) into a side-blowing furnace for oxygen-enriched smelting to obtain a high-temperature melt and high-temperature flue gas; (4) sending the high-temperature melt into an electric furnace for sedimentation separation, and discharging blister copper and furnace slag from a copper discharge port and a slag discharge port respectively; (5) the high-temperature flue gas is sent into a combustion chamber for combustion, then sent into a waste heat boiler for waste heat recovery and partial dust collection, sent into a cloth bag dust collection device for smelting smoke dust collection after being cooled by a quench tower, sent into a secondary spray tower by an exhaust fan for spray treatment, and finally treated by an electric demister for emptying. The matte making process is rapid, can well trap the noble metal in the waste circuit board, fully recover resources, effectively prevent and reduce the generation of dioxin, and has the advantages of high treatment efficiency, low cost and good environmental protection.)

1. The method for smelting and treating the waste circuit board by the oxygen-enriched side-blown furnace is characterized by comprising the following steps of:

(1) crushing raw materials: crushing the waste circuit board by using a crusher to obtain circuit board crushed materials;

(2) preparing materials: mixing the circuit board crushed aggregates obtained in the step (1) and auxiliary materials in proportion to obtain mixed furnace burden;

(3) side-blown smelting: feeding the mixed furnace burden obtained in the step (2) into a side-blowing furnace for smelting, blowing oxygen-enriched air into the furnace through a spray gun, controlling the atmosphere in the furnace, maintaining the temperature of a molten pool at 1150-1300 ℃, adding coal powder, carrying out oxidation reaction on metal elements and organic matters in the mixed furnace burden, carrying out slagging reaction on metal oxides and a flux, and carrying out side-blowing smelting on the mixed furnace burden to obtain a high-temperature melt and high-temperature flue gas;

(4) melt processing: sending the high-temperature melt obtained in the step (3) into an electric furnace for sedimentation separation, layering slag and blister copper in the melt in the electric furnace due to different densities, respectively discharging the blister copper and the slag from a copper discharging port and a slag discharging port of the electric furnace, and piling the slag after water quenching treatment;

(5) flue gas treatment: and (4) feeding the high-temperature flue gas generated in the step (4) into a combustion chamber for combustion, then feeding the high-temperature flue gas into a waste heat boiler for waste heat recovery and partial dust collection, feeding the high-temperature flue gas into a cloth bag dust collection device for smelting smoke dust collection after cooling by a quench tower, feeding the high-temperature flue gas into a secondary spray tower for spray treatment by an exhaust fan, and finally emptying the high-temperature flue gas after treatment by an electric demister.

2. The method of claim 1, wherein the particle size of the circuit board scrap in step (1) is 20-40 mm.

3. The method of claim 1, wherein the supplementary material in step (2) comprises one or both of limestone and waste lime powder.

4. The method of claim 1, wherein in step (2), the mixing ratio of the circuit board scrap, the auxiliary material, and the melting fumes is adjusted according to the composition of the circuit board.

5. The method of claim 1, wherein the oxygen-enriched air in step (3) has a pressure of 0.16 to 0.20MPa, an oxygen concentration of 25 to 50V%, and preferably an oxygen concentration of 40 to 60V%.

6. The method of claim 1, wherein smelting fumes captured in step (5) are returned to step (2) for proportioning with circuit board scrap and auxiliary materials.

7. The method of claim 1, wherein the flue gas treated in the combustor in step (5) has a CO content of less than 0.006V%.

8. The method according to claim 1, characterized in that in step (5), the outlet flue gas temperature of the waste heat boiler is controlled to be above 500 ℃.

9. The method according to claim 1, wherein in the step (5), the temperature of the flue gas entering the quenching tower from the waste heat boiler is suddenly reduced from more than 500 ℃ to 150-160 ℃ within 1 s.

10. The method of claim 1, wherein when the flame retardant in the waste circuit board contains bromine, the secondary spray tower in the step (5) sprays an alkaline solution to absorb SO in the flue gas₂HBr, HCl gas and recovering the bromide salt.

Technical Field

The invention belongs to the technical field of pyrogenic process treatment of waste circuit boards, and relates to a method for smelting and treating the waste circuit boards by an oxygen-enriched side-blown furnace.

Background

The content of metal in the waste circuit board is generally more than 40%, the waste circuit board mainly contains valuable metals with recovery value, such as Cu, Fe, Ni, Zn and precious metals, such as Au, Ag, Pt, Pd and the like, and the waste circuit board also contains various harmful components, such as organic plastics, polybrominated biphenyls and the like. If the waste circuit board cannot be effectively treated, the environment is greatly polluted and the waste of recyclable resources is caused, so that the method has important significance for realizing green and efficient recycling of valuable metals in the waste circuit board.

Aiming at the main valuable metal Cu in the waste circuit board, the adopted main recovery processing technology comprises the following steps: mechanical physical recovery technology and chemical recovery processing technology. The mechanical physical recovery technology comprises mineral processing technologies such as magnetic separation, hammer milling, airflow separation, electric separation and the like, and has the advantages of simple operation, low pollution, low energy consumption and the like. However, the degree of dependence of the treatment effect on the monomer dissociation degree of the materials is high, and noise and harmful dust containing glass fiber and organic resin are easily generated, so that mechanical physical treatment is often used as a pretreatment process in combination with a pyrogenic process and a wet recovery process.

The chemical recovery treatment technology mainly comprises a hydrometallurgy technology and a pyrogenic treatment technology. The wet metallurgy is to dissolve the metal in the pretreated waste circuit board in the medium of strong acid, alkali (sulfuric acid, nitric acid, ammonia water-ammonium salt) and the like, and then to recover the metal by means of extraction, electrolysis, leaching, distillation and the like. The hydrometallurgical treatment technology has the advantages of high recovery rate, no generation of toxic and harmful gases (dioxin and the like), and the like, but the development of the hydrometallurgical treatment technology is limited by the defects of more complex process, longer recovery time, strict requirement on sewage treatment process and the like.

The pyrogenic process treatment technology mainly adopts the modes of incineration, sintering, smelting and the like to decompose organic matters in the waste circuit board and recover valuable metals in the waste circuit board. The pyrogenic process treatment has the advantages of simple process, large treatment capacity, high efficiency and the like. In the pyrogenic process, how to inhibit the generation of dioxin is a technical problem which needs to be solved urgently.

Disclosure of Invention

The invention mainly aims to provide a method for smelting and treating waste circuit boards by using an oxygen-enriched side-blown furnace, which has the advantages of high treatment efficiency, low cost and good environmental protection. The invention is based on the generation mechanism of dioxin: (1) high-temperature gas phase generation; (2) macromolecular carbon (residual carbon) and chloride in the fly ash are synthesized at low temperature (250-400 ℃), the optimal synthesis of dioxin is about 300 ℃, but the synthesis of dioxin is possible at the temperature of above 400 ℃, and the dioxin cannot be synthesized when the temperature reaches above 800 ℃; (3) dioxin precursors (such as chlorophenol and the like) generated by poor combustion are generated by mutual reaction of the precursors under the action of catalysts (such as Fe, Cu and Ni) on the surface of the fly ash. The temperature of the flue gas at the outlet of the waste heat boiler is controlled to be 500 ℃, and the temperature of the flue gas is rapidly reduced to 150-160 ℃ from 500 ℃ in 1s after the flue gas passes through a quenching tower, so that the flue gas rapidly crosses a dioxin resynthesis temperature range (250-400 ℃), and the synthesis of dioxin is effectively prevented or reduced.

The method provided by the invention treats the waste circuit board by oxygen-enriched side-blown smelting, depends on the advantages of large smelting treatment capacity of the molten pool, wide raw material applicability, high smelting efficiency, effective control of dioxin in flue gas and the like, and comprehensively recovers copper and other valuable metals in the waste circuit board. The organic components in the waste circuit board are rapidly decomposed in a high-temperature molten pool; the copper and sulfur generated by smelting can be used as a trapping agent of noble metals in the waste circuit board, and the slagging discharge of glass fibers and the like in the waste circuit board realizes the effective and simple separation of valuable metals, organic components and glass fibers. Blowing oxygen-enriched air to fully oxidize a precursor of the dioxin; the temperature of the outlet of the waste heat boiler is controlled at 500 ℃, and the temperature of the flue gas is quickly reduced by the quenching tower, so that the generation of dioxin is effectively prevented, and the environmental protection requirement of the smelting process is met.

The specific technical scheme of the invention is as follows. The method for smelting and treating the waste circuit board by the oxygen-enriched side-blown furnace comprises the following steps:

(1) crushing raw materials: crushing the waste circuit board by using a crusher to obtain circuit board crushed materials;

(2) preparing materials: mixing the circuit board crushed aggregates obtained in the step (1) and auxiliary materials in proportion to obtain mixed furnace burden;

(3) side-blown smelting: feeding the mixed furnace burden obtained in the step (2) into a side-blowing furnace for smelting, blowing oxygen-enriched air into the furnace through a spray gun, controlling the atmosphere in the furnace, maintaining the temperature of a molten pool at 1150-1300 ℃, adding pulverized coal, carrying out oxidation reaction on metal elements (Fe, Pb, Zn and the like) and organic matters in the mixed furnace burden, carrying out slagging reaction on metal oxides and a flux, and carrying out side-blowing smelting on the mixed furnace burden to obtain a high-temperature melt and high-temperature flue gas;

(4) melt processing: sending the high-temperature melt obtained in the step (3) into an electric furnace for sedimentation separation, layering slag and blister copper in the melt in the electric furnace due to different densities, floating on the blister copper phase due to smaller density of a slag phase, discharging the blister copper and the slag from a copper discharging port and a slag discharging port of the electric furnace respectively, and piling the slag after water quenching treatment;

(5) flue gas treatment: and (4) feeding the high-temperature flue gas generated in the step (4) into a combustion chamber for combustion, then feeding the high-temperature flue gas into a waste heat boiler for waste heat recovery and partial dust collection, feeding the high-temperature flue gas into a cloth bag dust collection device for smelting smoke dust collection after cooling by a quench tower, feeding the high-temperature flue gas into a secondary spray tower for spray treatment by an exhaust fan, and finally emptying the high-temperature flue gas after treatment by an electric demister.

Further, in the step (1), the particle size of the circuit board crushed aggregates is about 20-40 mm.

Further, in the step (2), the auxiliary materials include one or two of limestone and waste lime powder.

Further, in the step (2), the mixing ratio of the circuit board crushed aggregates, the auxiliary materials and the smelting smoke dust is adjusted according to different components of the circuit board.

Further, in the step (3), the pressure of the oxygen-enriched air is 0.16-0.20 Mpa, the oxygen concentration is 25-50V% (V% is volume percentage, the same below), and the oxygen concentration is preferably 40-60V%.

And (3) further, returning the smelting smoke dust collected in the step (5) to the step (2) to be proportioned with the circuit board crushed aggregates and auxiliary materials.

Further, in the step (5), the flue gas is subjected to secondary combustion in the combustion chamber to remove CO in the flue gas, and the CO content of the flue gas treated by the combustion chamber is below 0.006V%.

Further, in the step (5), the temperature of the flue gas at the outlet of the waste heat boiler is controlled to be more than 500 ℃.

Further, in the step (5), the temperature of the flue gas entering the quenching tower from the waste heat boiler is suddenly reduced to 150-160 ℃ from above 500 ℃ within 1s, the temperature of the flue gas rapidly crosses over a synthesis temperature area (250-400 ℃) of the dioxin, and the resynthesis of the dioxin is effectively reduced.

Further, in the step (5), when the flame retardant in the waste circuit board contains bromine, the secondary spray tower in the step (5) spraysThe alkaline solution is sprayed to effectively absorb SO in the flue gas₂HBr, HCl and the like and recovering bromine salt.

The innovation of the invention is that:

the invention adopts the oxygen-enriched side-blowing process, the materials are mixed and then added into the molten pool, the oxygen-enriched air is blown in to form violent stirring to the melt in the molten pool, and the processes of mass transfer and heat transfer in the molten pool are rapidly carried out, so that the matte making process is rapidly completed. The molten pool has better mass transfer conditions, the copper matte can better trap the precious metals in the waste circuit board, and the resources in the waste circuit board are fully and comprehensively recovered. Organic matters and flame-retardant components in the waste circuit board are fully reacted in a high-temperature oxygen-enriched atmosphere, so that the generation of CO and dioxin in smoke is reduced. The subsequent control of the exhaust-heat boiler and the quench tower on the flue gas temperature enables the flue gas temperature to quickly cross the resynthesis temperature (250-400 ℃) of dioxin, so that the generation of the dioxin is effectively prevented and reduced, and the subsequent secondary spray tower performs alkali absorption on HBr and HCl in the flue gas and produces bromine salt, so that the whole process flow has better environmental protection performance.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

Detailed Description

The invention is further explained below with reference to the drawings and the embodiments.

Referring to the attached drawings, the method for treating the waste circuit board by the oxygen-enriched side-blown smelting process comprises the following steps:

(1) crushing the waste circuit board by using a crusher, wherein the granularity of the crushed circuit board is about 20-40 mm, and feeding crushed circuit board materials into the step (2);

(2) preparing materials: (1) mixing the circuit board obtained in the step (3) with auxiliary materials of 0.37t/h limestone and 0.06t/h waste lime powder in a ratio of 2.4t/h by using a rubber belt conveyor, uniformly mixing;

(3) side-blown smelting: feeding the mixed furnace burden obtained in the step (2) into a side-blowing furnace for smelting, blowing oxygen-enriched air with the oxygen concentration of 30-50% and the pressure of 0.16-0.20 Mpa into the furnace through a spray gun, controlling the atmosphere in the furnace, maintaining the temperature of a molten pool at 1150-1300 ℃, enabling the melt in the molten pool to form a strong stirring effect, adding pulverized coal, carrying out oxidation reaction on elements such as Fe, Pb and Zn and organic matters in the raw materials, carrying out slagging reaction on metal oxides and a flux, and reacting the raw materials to obtain high-temperature melt, namely furnace slag, blister copper and high-temperature flue gas;

the main reactions occurring in the molten pool during the smelting process are:

CH₄+2O₂＝CO₂+2H₂O

C+O₂＝CO₂

C+CO₂＝2CO

Cu(s)＝Cu(l)

2Me+O₂2MeO (Me is Pb, Zn, Pd, Pt, Au, Ag, etc.)

4Cu+O₂＝2Cu₂O

O₂+2Fe＝2FeO

Cu₂O+CO＝2Cu+CO₂

CuO+CO＝Cu+CO₂

CaCO₃＝CaO+CO₂

6FeO+O₂＝2Fe₃O₄

2FeO+SiO₂＝2FeO·SiO₂

CaO+SiO₂＝CaSiO₃

Part of organic matters in the raw materials are subjected to combustion reaction in the furnace to provide a heat source for the smelting process, and the rest of the organic matters are subjected to secondary combustion in the inlet section of the boiler and combustion air blown in layers. The main reactions that occur upon combustion of organic matter are as follows:

C₂H₄+3O₂＝2CO₂+2H₂O

4C₂H₇N+15O₂＝8CO₂+14H₂O+2N₂

2C₇H₈O+17O₂＝14CO₂+8H₂O

C₆H₅Br+7O₂＝6CO₂+2H₂O+HBr

C₆H₅Cl+7O₂＝HCl+6CO₂+2H₂O

(4) melt processing: sending the high-temperature melt obtained in the step (3) into an electric furnace for sedimentation separation, layering slag and blister copper in the melt in the electric furnace due to different densities, floating on the blister copper phase due to smaller density of a slag phase, discharging the blister copper and the slag from a copper discharging port and a slag discharging port of the electric furnace respectively, and piling the slag after water quenching treatment;

(5) flue gas treatment: feeding the flue gas generated in the smelting process in the step (4) into a combustion chamber to remove CO in the flue gas, wherein the CO content of the flue gas treated by the combustion chamber is less than 0.006 (V%); then the waste heat is recycled and part of dust is collected in a waste heat boiler, and the temperature of the flue gas is controlled to be about 500 ℃ after the waste heat boiler is used for processing; then sending the mixture to a quenching tower to cool to 150-160 ℃, and then sending the mixture to a cloth bag dust collecting device to collect smoke dust; the flue gas is sent into a secondary spray tower by an exhaust fan to absorb SO in the flue gas by alkali₂And HBr, HCl and other harmful gases are recycled to obtain bromine salt, and the bromine salt is discharged through an electric demister.

The main nonmetal chemical components and ash components of the waste circuit board are shown in the following table