阅读说明：本技术 一种去除废杂铜合金中铅杂质的方法及装置 (Method and device for removing lead impurities in scrap copper alloy ) 是由 李亚琼 张立峰 施利霞 符志祥 蔡新雨 刘力刚 赵震 任强 于 2021-01-08 设计创作，主要内容包括：本发明公开了一种去除废杂铜合金中铅杂质的方法及装置,属于再生铜熔体净化技术领域。本发明的一种去除废杂铜合金中铅杂质的方法及装置,通过对熔融电解液进行电解制备阴极电解产物,该阴极电解产物与废杂铜合金熔体杂质铅反应生产Pb-Ca化合物,同时通过底吹惰性气体使Pb-Ca化合物在废杂铜合金熔体内聚合并上浮至熔融电解液,最后将熔融电解液和废杂铜合金熔体分离得到低铅杂质的铜合金；可从熔融电解液制备得到高纯金属单质钙,方法简单,过程可控、简单,仅需调整电化学参数来控制钙的电解反应的快慢；避免了使用高成本单质钙与低纯度的含钙合金,极大提高了技术的经济性。同时,生产过程中产生Cl2,可以增加技术的经济性。(The invention discloses a method and a device for removing lead impurities in scrap copper alloy, belonging to the technical field of purification of reclaimed copper melt. The invention relates to a method and a device for removing lead impurities in scrap copper alloy, which are characterized in that a cathode electrolysis product is prepared by electrolyzing molten electrolyte, the cathode electrolysis product reacts with scrap copper alloy melt impurity lead to produce a Pb-Ca compound, meanwhile, the Pb-Ca compound is polymerized in the scrap copper alloy melt and floats to the molten electrolyte by bottom blowing of inert gas, and finally, the molten electrolyte and the scrap copper alloy melt are separated to obtain the copper alloy with low lead impurities; the method is simple, the process is controllable and simple, and the speed of the electrolytic reaction of the calcium is controlled only by adjusting electrochemical parameters; avoids using high-cost simple substance calcium and low-purity calcium-containing alloy, and greatly improves the economical efficiency of the technology. Meanwhile, Cl2 is generated in the production process, so that the technical economy can be improved.)

1. A method for removing lead impurities in scrap copper alloy is characterized by comprising the following steps: preparing a cathode electrolysis product (113) by electrolyzing the molten electrolyte (130), reacting the cathode electrolysis product (113) with lead impurities in the scrap copper alloy melt (140) to produce a Pb-Ca compound, polymerizing the Pb-Ca compound in the scrap copper alloy melt (140) and floating up to the molten electrolyte (130), and finally separating the molten electrolyte (130) and the scrap copper alloy melt (140) to obtain the copper alloy with low lead impurities.

2. The method for removing the lead impurities in the scrap copper alloy according to claim 1, which is characterized by comprising the following steps:

step one, electrolyzing to prepare calcium

Inserting a cathode (111) into the scrap copper alloy melt (140), inserting an anode (121) into the molten electrolyte (130), and heating and electrolyzing the molten electrolyte (130) to prepare a cathode electrolysis product (113);

step two, lead impurity removal

Reacting the cathode electrolysis product (113) generated in the step one with impurity lead in the scrap copper alloy melt (140) to produce a Pb-Ca compound, wherein the Pb-Ca compound is polymerized in the scrap copper alloy melt (140) and floats to the molten electrolyte (130);

step three, separation

And cooling the molten electrolyte (130) obtained in the step two and the scrap copper alloy melt (140) and separating to obtain the copper alloy with low lead impurity.

3. The method for removing lead impurities in scrap copper alloy according to claim 2, wherein: in the first step, the cathode (111) is isolated from the molten electrolyte (130) by a ceramic through pipe (112).

4. The method for removing lead impurities in scrap copper alloy according to claim 2, wherein: in the first step, the molten electrolyte (130) is CaCl2-M mixed molten salt, wherein the component of M is one or more of LiCl, KF, CaF2 and KCl; the content of CaCl2 is 5-30%, the concentration of lead in the scrap copper alloy melt (140) is 0.3-8.5%, and the mass ratio of the scrap copper melt (140) to CaCl2 in the molten electrolyte (130) is 200: 1-20: 1.

5. The method for removing lead impurities in scrap copper alloy according to claim 2, wherein: in the first step, the current density of the anode during electrolysis is 1.0-3.5A/cm 2, and the heating temperature is 780-1100 ℃.

6. The method for removing lead impurities in scrap copper alloy according to claim 2, wherein: and the second step also comprises air blowing treatment, and the specific step is that inert gas (150) is blown into the scrap copper alloy melt (140) under the cathode (111).

7. The method for removing lead impurities in scrap copper alloy according to claim 2, wherein: the third step comprises the following specific steps: and (3) cooling the molten electrolyte (130) and the scrap copper alloy melt (140) obtained in the step two, then carrying out physical separation, and cutting to remove the surface of the cooled scrap copper alloy melt (140) with the ingot thickness of 2%, thereby finally obtaining the low-lead impurity copper alloy.

8. The utility model provides a get rid of device of plumbous impurity in miscellaneous copper alloy of waste which characterized in that: comprises a cathode electrolysis unit (110) and an anode electrolysis unit (120), wherein the cathode electrolysis unit (110) and the anode electrolysis unit (120) are connected with a power supply through leads, and in addition, a closed loop is formed by a molten electrolyte (130) and a scrap copper alloy melt (150).

9. The apparatus for removing lead impurities from scrap copper alloy according to claim 8, wherein: the cathode electrolysis unit (110) comprises a cathode (111) and a ceramic through pipe (112), wherein the cathode (111) is made of an inert material, the ceramic through pipe (112) is wrapped and assembled on the periphery of the cathode (111), and the height of the ceramic through pipe (112) is larger than the thickness of the molten electrolyte (130).

10. The apparatus for removing lead impurities from scrap copper alloy according to claim 8, wherein: the cathodic electrolysis unit (110) is disposed in the scrap copper alloy melt (140) and the anodic electrolysis unit (120) is disposed in the molten electrolyte (130).

Technical Field

The invention relates to the technical field of secondary copper melt purification, in particular to a method and a device for removing lead impurities in scrap copper alloy.

Technical Field

Copper alloys are based on copper, and metals such as Sn or Zn can be formulated to form alloys such as bronze and brass. A small amount of metal Pb (2%) is added into the alloy, so that the cutting performance and the wear resistance of the alloy can be obviously improved. The lead-containing copper alloy has wide application and important function, such as pipe castings and fittings of civil water supply systems, screw mechanical parts in the manufacturing industry, fittings of electrical elements, clothes, toys and the like. It is noted that lead is extremely toxic and can have adverse effects on human health and the environment. Since lead has low solubility in copper alloys and is dispersed in the form of fine particles in the alloys, its side effects are the same as those of the simple substance of lead. The development and use of green lead-free copper alloys is becoming increasingly important in order to reduce or avoid the detrimental effects of lead in copper alloys, and is becoming a mandatory legal requirement in some countries.

In order to relieve the pressure of copper resource shortage in China, scrap copper alloy becomes the first choice raw material for preparing copper alloy. However, the scrap brass contains high content of Pb, and an effective means for removing lead is required to promote the recycling of scrap copper. At present, people carry out a great deal of research on waste lead-copper alloy, and the lead removing method mainly comprises the following steps:

(1) electrical pulse method, by search as english journal article: journal of Cleaner Production 276(2020)123358, author: xiaooshan Huang, Hongliang ZHao, Chengyan Wang, Xinfang Zhang, article title: the One-step separation of hazardous element lead in the glass alloy by physical external field discloses a method for removing Pb impurities in waste brass alloy by electric pulse, which specifically comprises the following steps: the scrap brass alloy is used as a raw material, when the alloy is completely melted, electric pulse is applied, then the temperature is reduced, the sample is solidified, Pb is enriched in the anode, and the removal rate is as high as 86.7%. The method has strong innovation and replaces the melt pollution caused by the use of molten salt. But the lead removal efficiency is low, continuous production cannot be carried out, and the requirements on operation procedures and equipment are high.

(2) Ca compound approach, retrieved as english journal article: MATERIALS TRANSACTIONS,46(2005)2719-2724, author: nakano, n.t.rochman, h.sueyoshi, title of the article: removal of Lead from spreader Alloy scans by Compound-Separation Method; and after retrieval, the Chinese characters are as follows: metals,69(2005) 198-; the authors: nakano, k.higashiriki, n.t.rochman, k.yamada, k.hamashi, h.sueyoshi article title: a Removal of Lead from fibre by compound-separation method; and after retrieval, the Chinese characters are as follows: materials Transactions, Vol.47, No.12(2006) pp.2997-3000; the authors: atsushi Nakano, Naoki Kajiya, Kosaku Yamada, Syun-ichi Nakamura, Takehiko Matsuda, Hidekazu Sueyoshi, article title: removal of Lead from Scap Brown. The article discloses a method for removing Pb impurities in scrap copper alloy by using a calcium compound method, which specifically comprises the following steps: scrap copper alloy is taken as a raw material, calcium-containing metal simple substance or alloy is added for co-melting, and compounds such as Ca2Pb, Ca5Pb3 and the like are generated through chemical reaction between Ca and Pb. Because the melting point of the copper alloy is higher than the melting temperature of the copper alloy, the copper alloy exists as solid-phase particles and is removed after the solid-phase particles float to the surface of the melt to form a slag agent. And certain NaF is added to strengthen Pb removal. The method is simple to operate, and can realize the continuous lead removal process of the scrap copper. However, the calcium metal simple substance or calcium alloy has high cost, and the used fluoride has high volatility and toxicity and is easy to cause environmental pollution.

Disclosure of Invention

1. Technical problem to be solved by the invention

The invention aims to solve the problems of complex process, high equipment requirement, low purification efficiency, high cost and the like in the prior art for removing Pb impurities in scrap copper alloy, and provides a method and a device for removing the Pb impurities in the scrap copper alloy.

2. Technical scheme

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the invention relates to a method for removing lead impurities in scrap copper alloy, which comprises the steps of electrolyzing molten electrolyte to prepare a cathode electrolysis product, reacting the cathode electrolysis product with scrap copper alloy melt impurity lead to produce a Pb-Ca compound, polymerizing and floating the Pb-Ca compound in the scrap copper alloy melt to the molten electrolyte, and finally separating the molten electrolyte from the scrap copper alloy melt to obtain the copper alloy with low lead impurities.

Preferably, the specific steps are as follows:

step one, electrolyzing to prepare calcium

Inserting a cathode into the scrap copper alloy melt, inserting an anode into the molten electrolyte, and heating and electrolyzing the molten electrolyte to prepare a cathode electrolysis product;

step two, lead impurity removal

Reacting the cathode electrolysis product generated in the step one with scrap copper alloy melt impurity lead to produce a Pb-Ca compound, wherein the Pb-Ca compound is polymerized in the scrap copper alloy melt and floats to molten electrolyte;

step three, separation

And cooling the molten electrolyte and the scrap copper alloy melt obtained in the step two, and separating to obtain the low-lead impurity copper alloy.

Preferably, in step one, the cathode is blocked from contacting the molten electrolyte by a ceramic through pipe.

Preferably, in the step one, the molten electrolyte is CaCl2-M mixed molten salt, wherein the component of M is one or more of LiCl, KF, CaF2 and KCl; the content of CaCl2 is 5-30%, the concentration of lead in the scrap copper alloy melt is 0.3-8.5%, and the mass ratio of the scrap copper melt to the molten electrolyte CaCl2-M mixed molten salt is 200: 1-20: 1.

Preferably, the current density of the anode during electrolysis in the first step is 1.0-3.5A/cm 2, and the heating temperature is 780-1100 ℃.

Preferably, the second step further comprises a blowing treatment, and the specific step is to blow inert gas into the scrap copper alloy melt, wherein the blowing position is positioned right below the cathode.

Preferably, the specific steps of step three are: and (4) cooling the molten electrolyte and the scrap copper alloy melt obtained in the step two, then carrying out physical separation, and cutting to remove the surface of the cooled scrap copper alloy melt ingot with the thickness of 2%, thereby finally obtaining the low-lead impurity copper alloy.

Preferably, the device comprises a cathode electrolysis unit and an anode electrolysis unit, wherein the cathode electrolysis unit and the anode electrolysis unit are connected with a power supply through leads, and in addition, a closed loop is formed by melting electrolyte and scrap copper alloy melt.

Preferably, the cathode electrolysis unit comprises a cathode and a ceramic through pipe, wherein the cathode is made of inert materials, the ceramic through pipe is wrapped and assembled on the periphery of the cathode, and the height of the ceramic through pipe is larger than the thickness of the molten electrolyte.

Preferably, the cathodic electrolysis unit is disposed in the scrap copper alloy melt and the anodic electrolysis unit is disposed in the molten electrolyte.

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:

(1) the invention relates to a method and a device for removing lead impurities in scrap copper alloy, which are characterized in that a cathode electrolysis product is prepared by electrolyzing molten electrolyte, the cathode electrolysis product reacts with scrap copper alloy melt impurity lead to produce a Pb-Ca compound, the Pb-Ca compound is polymerized in the scrap copper alloy melt and floats to the molten electrolyte, and finally the molten electrolyte and the scrap copper alloy melt are separated to obtain the copper alloy with low lead impurities; the method is simple, the process is controllable and simple, and the speed of the electrolytic reaction of the calcium is controlled only by adjusting electrochemical parameters; avoids using high-cost simple substance calcium and low-purity calcium-containing alloy, and greatly improves the economical efficiency of the technology. Meanwhile, Cl2 is generated in the production process, so that the technical economy can be improved;

(2) according to the method and the device for removing the lead impurities in the scrap copper alloy, a cathode electrolysis product reacts with the scrap copper alloy melt impurity lead to produce a Pb-Ca compound, meanwhile, inert gas is blown into the scrap copper alloy melt under the cathode, and the Pb-Ca compound is polymerized in the scrap copper alloy melt and floats to the molten electrolyte under the action of the inert gas; the Pb-Ca chemical has higher melting point and is an inclusion in the melt, and the Pb-Ca chemical mainly exists in the scrap copper alloy melt in the form of small-size inclusion which is difficult to float upwards for removal; therefore, the collision, the polymerization and the growth of the Pb-Ca compound are promoted by blowing the inert gas at the bottom, the Pb-Ca compound is driven to float upwards to be removed by the action of bubbles, and the removal of the small-size Pb-Ca compound is effectively promoted by blowing the inert gas at the bottom;

(3) according to the method and the device for removing the lead impurities in the scrap copper alloy, disclosed by the invention, the molten electrolyte is CaCl2-M mixed molten salt, wherein the component of M is one or more of LiCl, KF, CaF2 and KCl, and the content of CaCl2 is 5-30%; the density of the molten electrolyte is controlled within the range of 1.38-1.58 g/cm3, because the density of the metal calcium at the melting point temperature (842oC) is 1.36g/cm 3; because of the density difference, the electrolyzed Ca melt can be positioned between the scrap copper alloy melt with high density at the bottom and the low density molten electrolyte at the top, namely, the Ca melt is positioned in the middle of the melt, so that the electrolyzed Ca melt can be protected by the molten salt and isolated from air without being oxidized, the utilization rate of Ca is greatly improved, and the lead removal effect is enhanced;

(4) the invention relates to a method and a device for removing lead impurities in scrap copper alloy, which comprises a cathode electrolysis unit and an anode electrolysis unit, wherein the cathode electrolysis unit comprises a cathode and a ceramic through pipe, the ceramic through pipe is wrapped and assembled at the periphery of the cathode, and the height of the ceramic through pipe is greater than the thickness of molten electrolyte; the ceramic through pipe has the functions of preventing the cathode from contacting with the molten electrolyte and preventing metal Ca from being directly generated in the molten electrolyte in the electrolysis process, wherein the metal Ca cannot be directly reacted with impurity lead in the scrap copper alloy melt; the cathode is prevented from being directly inserted into the scrap copper alloy melt, the bottom of the cathode can be provided with a negative electric field in the electrolytic process, Ca2+ in the molten electrolyte can enter the scrap copper alloy melt under the action of the electric field force, and meanwhile, the cathode reaction can be carried out to generate metal Ca, the scrap copper alloy melt contains a large amount of impurity lead, and the metal Ca can react with the impurity lead to generate a Pb-Ca compound;

(5) according to the method and the device for removing the lead impurities in the scrap copper alloy, the small-flow inert gas is blown into the scrap copper alloy melt, the flow is small, the size of the bubbles is kept small, the bubbles are dispersed and distributed into the scrap copper alloy melt, impurities such as lead and metal calcium can be adsorbed around the small bubbles, dynamic conditions are provided for chemical reaction, and the impurity removal efficiency is improved.

Drawings

FIG. 1 is a schematic view of an apparatus for removing lead impurities from scrap copper alloy according to the present invention.

The reference numerals in the schematic drawings illustrate:

110. a cathodic electrolysis unit; 111. a cathode; 112. a ceramic through pipe; 113. cathodically electrolyze the product;

120. an anodic electrolysis unit; 121. anode, 122, anode electrolysis product;

130. melting the electrolyte; 140. scrap copper alloy melt; 150. an inert gas.

Detailed Description

The detailed description and exemplary embodiments of the invention will be better understood when read in conjunction with the appended drawings, where the elements and features of the invention are identified by reference numerals.

Example 1

Referring to fig. 1, the method for removing lead impurities from scrap copper alloy of this embodiment includes the following steps: the molten electrolyte 130 is electrolyzed to prepare a cathode electrolysis product 113, the cathode electrolysis product 113 reacts with impurity lead in the scrap copper alloy melt 140 to produce Pb-Ca compound, the Pb-Ca compound is polymerized in the scrap copper alloy melt 140 and floats to the molten electrolyte 130, and finally the molten electrolyte 130 and the scrap copper alloy melt 140 are separated to obtain the copper alloy with low lead impurity. The method comprises the following specific steps:

step one, preparing Ca by electrolysis

Firstly, a ceramic through pipe 112 is used for preventing a cathode 111 from contacting a molten electrolyte 130, then the cathode 111 is inserted into a scrap copper alloy melt 140, an anode 121 is inserted into the molten electrolyte 130, and a cathode electrolysis product 113 is prepared by electrolysis under the conditions that the heating temperature of the molten electrolyte 130 is 780-1100 ℃ and the anode current density is 1.0-3.5A/cm 2;

in this embodiment, for preparing calcium metal to remove lead, the ceramic through pipe 112 is selected to prevent the cathode 111 from contacting the molten electrolyte 130, and at the same time, the bottom of the cathode 111, i.e., the electrode part without the ceramic through pipe 112, is inserted into the scrap copper alloy melt 140, and the anode 121 is inserted into the molten electrolyte 130, so that the electrolyzed calcium metal firstly enters the scrap copper alloy melt 140, moves upwards in the scrap copper alloy melt 140 under the action of buoyancy, and reacts with lead during the movement, thereby increasing the reaction probability of calcium and lead and improving the lead removal efficiency.

In addition, the molten electrolyte 130 of the embodiment is CaCl2-M mixed molten salt, wherein the component of M is one or more of LiCl, KF, CaF2 and KCl; the content of CaCl2 is 5-30%, the concentration of lead in the scrap copper alloy melt 140 is 0.3-8.5%, and the mass ratio of the scrap copper melt 140 to the CaCl2-M mixed molten salt in the molten electrolyte 130 is 200: 1-20: 1.

Step two, lead impurity removal

Reacting the cathode electrolysis product 113 generated in the first step with impurity lead in the scrap copper alloy melt 140 to produce a Pb-Ca compound, blowing inert gas 150 into the scrap copper alloy melt 140 under the cathode 111, wherein the inert gas 150 is Ar and/or N2, and under the action of the inert gas 150, the Pb-Ca compound is polymerized in the scrap copper alloy melt 140 and floats to the molten electrolyte 130; since the Pb-Ca chemical has a high melting point and is an inclusion in the melt, the Pb-Ca chemical exists mainly in the scrap copper alloy melt 140 in the form of small-sized inclusion, and the small-sized inclusion is difficult to float upwards for removal. Therefore, the collision, polymerization and growth of the Pb-Ca compound are promoted by bottom blowing the inert gas 150, the Pb-Ca compound is driven to float upwards and be removed by the action of bubbles, and the removal of the small-size Pb-Ca compound is effectively promoted by bottom blowing the inert gas 150.

Step three, separation

And (3) cooling the molten electrolyte 130 and the scrap copper alloy melt 140 obtained in the step (II), then carrying out physical separation, and cutting to remove the surface of the cooled scrap copper alloy melt 140 with the thickness of 2% of the ingot, thereby finally obtaining the low-lead impurity copper alloy.

It should be noted that the density of the molten electrolyte 130 used in this embodiment is controlled within the range of 1.38-1.58 g/cm3, since the density of calcium metal at the melting point temperature (842oC) is 1.36g/cm 3. Because the density difference enables the electrolyzed calcium melt to be positioned between the scrap copper alloy melt 140 with high density at the bottom and the low density molten electrolyte 130 at the top, namely, in the middle of the melt, the electrolyzed calcium melt is protected by the molten salt and isolated from the air without being oxidized, the utilization rate of calcium is greatly improved, and the lead removal effect is enhanced accordingly.

In addition, the embodiment can prepare the high-purity elemental metal Ca from the CaCl2-M mixed molten salt through electrolysis, the method is simple, the process is controllable and simple, and the speed of the electrolytic reaction of the calcium is controlled only by adjusting electrochemical parameters. Avoids using high-cost simple substance calcium and low-purity calcium-containing alloy, and greatly improves the economical efficiency of the technology. Meanwhile, Cl2 is generated in the production process, so that the technical economy can be improved.

The device for removing the lead impurities in the scrap copper alloy comprises a cathode electrolysis unit 110 and an anode electrolysis unit 120, wherein the cathode electrolysis unit 110 comprises a cathode 111 and a ceramic through pipe 112, the ceramic through pipe 112 is wrapped and assembled on the periphery of the cathode 111, the height of the ceramic through pipe 112 is greater than the thickness of a molten electrolyte 130, in addition, the cathode 111 is made of an inert material, and high-purity graphite is selected in the implementation; the cathode electrolysis unit 110 and the anode electrolysis unit 120 are connected with a power supply through leads, the cathode electrolysis unit 110 is arranged in the scrap copper alloy melt 140, and the anode electrolysis unit 120 is arranged in the molten electrolyte 130, so that the cathode electrolysis unit 110, the anode electrolysis unit 120, the molten electrolyte 130, the scrap copper alloy melt 150 and the power supply form a closed loop.

The ceramic through pipe 112 in this embodiment is used to prevent the cathode 111 from contacting the molten electrolyte 130, and prevent the metal calcium from directly generating in the molten electrolyte 130 during the electrolysis process, and the metal calcium cannot directly react with the lead impurity in the scrap copper alloy melt 140. The cathode 111 is prevented from being directly inserted into the scrap copper alloy melt 140, the bottom of the cathode 111 can be provided with a negative electric field in the electrolysis process, Ca2+ in the molten electrolyte 130 can enter the scrap copper alloy melt 140 under the action of the electric field force, and simultaneously the cathode reaction can be carried out to generate metal calcium, the scrap copper alloy melt 140 contains a large amount of impurity lead, and the metal Ca can react with the impurity lead to generate Pb-Ca compounds. And the inert gas 150 is blown into the scrap copper alloy melt 140 from the direction right below the cathode 111, so that the flow field in the scrap copper alloy melt 140 near the cathode 111 can be promoted to flow from bottom to top, the Pb-Ca compound can be promoted to float upwards and be removed, the components of the scrap copper alloy melt 140 can be uniform, and the impurity removal rate is improved.

It is worth to be noted that the inert gas 150 blown into the scrap copper alloy melt 140 has a small flow rate and a small bubble size, and is dispersed and distributed into the scrap copper alloy melt 140, so that impurities of lead and metal Ca can be adsorbed around the small bubbles, a dynamic condition is provided for a chemical reaction, and the impurity removal efficiency is improved.

The invention has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will, however, be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. The detailed description and drawings are to be regarded as illustrative rather than restrictive, and any such modifications and variations are intended to be included within the scope of the present invention as described herein. Furthermore, the background is intended to be illustrative of the state of the art as developed and the meaning of the present technology and is not intended to limit the scope of the invention or the application and field of application of the invention.