CN115151664A - Method for removing lead from brass - Google Patents
Method for removing lead from brass Download PDFInfo
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- CN115151664A CN115151664A CN202080088414.8A CN202080088414A CN115151664A CN 115151664 A CN115151664 A CN 115151664A CN 202080088414 A CN202080088414 A CN 202080088414A CN 115151664 A CN115151664 A CN 115151664A
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- lead
- zinc
- reduced pressure
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- brass scrap
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- 229910001369 Brass Inorganic materials 0.000 title claims abstract description 78
- 239000010951 brass Substances 0.000 title claims abstract description 78
- 238000000034 method Methods 0.000 title claims abstract description 51
- 239000011133 lead Substances 0.000 claims abstract description 94
- 239000011701 zinc Substances 0.000 claims abstract description 89
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 70
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 62
- 239000010949 copper Substances 0.000 claims abstract description 30
- 229910052802 copper Inorganic materials 0.000 claims abstract description 27
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000010438 heat treatment Methods 0.000 claims abstract description 24
- 238000009833 condensation Methods 0.000 claims abstract description 22
- 230000005494 condensation Effects 0.000 claims abstract description 22
- 238000002844 melting Methods 0.000 claims abstract description 22
- 230000008018 melting Effects 0.000 claims abstract description 22
- 238000009835 boiling Methods 0.000 claims abstract description 17
- 229910000881 Cu alloy Inorganic materials 0.000 claims abstract description 11
- 238000001704 evaporation Methods 0.000 claims abstract description 10
- 239000000203 mixture Substances 0.000 claims description 14
- TVZPLCNGKSPOJA-UHFFFAOYSA-N copper zinc Chemical compound [Cu].[Zn] TVZPLCNGKSPOJA-UHFFFAOYSA-N 0.000 claims description 6
- 238000000926 separation method Methods 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- 238000012360 testing method Methods 0.000 description 32
- 239000000463 material Substances 0.000 description 17
- 239000007789 gas Substances 0.000 description 7
- 229910052745 lead Inorganic materials 0.000 description 7
- 239000007790 solid phase Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 238000005292 vacuum distillation Methods 0.000 description 4
- 229910020218 Pb—Zn Inorganic materials 0.000 description 3
- 230000006698 induction Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000009530 blood pressure measurement Methods 0.000 description 2
- 238000009529 body temperature measurement Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000001304 sample melting Methods 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
- 235000013619 trace mineral Nutrition 0.000 description 1
- 238000009489 vacuum treatment Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/04—Refining by applying a vacuum
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/005—Separation by a physical processing technique only, e.g. by mechanical breaking
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/14—Refining in the solid state
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B13/00—Obtaining lead
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B15/00—Obtaining copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B19/00—Obtaining zinc or zinc oxide
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C3/00—Removing material from alloys to produce alloys of different constitution separation of the constituents of alloys
- C22C3/005—Separation of the constituents of alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C9/00—Alloys based on copper
- C22C9/04—Alloys based on copper with zinc as the next major constituent
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
A method of removing lead from brass scrap comprising: -heating brass scrap containing copper alloy, zinc and lead under reduced pressure at a temperature above the boiling point of lead under said reduced pressure but below the melting point of the copper base of the brass scrap under said reduced pressure, thereby evaporating lead and zinc, and-recovering the evaporated lead and zinc by condensation.
Description
Technical Field
The invention relates to a method for removing lead from brass scrap containing copper alloy, zinc and lead.
Background
Brass is an alloy with a 60/40 ratio of copper to zinc in the matrix. In addition, other elements are added to improve the properties of the final product. An example of such an additive is lead (Pb), which is added to improve the machinability of brass. Lead is typically added at a concentration of 1-4wt%, typically about 2wt%.
Brass is widely used for pipe applications due to its good corrosion resistance. As brass is widely used in faucets, many countries and organizations are striving to remove lead from brass to minimize human contact with lead from drinking water. At present, almost all recycled brass scrap contains lead, this causes difficulty in recovery. By improving the method of removing lead from brass scrap, the amount of brass that can be recovered can be increased, thereby achieving higher resource efficiency.
At present, there are 3 main methods for removing lead from brass-dilution, vacuum distillation of zinc and lead and intermetallic precipitation (intermetallic precipitation).
Diluting lead from brass scrap inventory requires intensive use of raw materials and is time consuming.
Vacuum distillation can be used to remove zinc and lead from brass in high yields, but the process requires energy.
Intermetallic compounds precipitate, resulting in the formation of precipitates of the CaPb alloy, and the resulting inclusions (inclusions) can lead to poor mechanical properties in the recovery of the metal.
Therefore, there is still a need for an improved method for removing lead from brass scrap that alleviates the deficiencies of the prior art methods.
Disclosure of Invention
It is an object of the present disclosure to provide a method of removing lead from brass scrap comprising copper alloy, zinc and lead which alleviates at least some of the disadvantages of existing lead removal methods.
It is another object of the present disclosure to provide a vacuum distillation method for removing lead from brass scrap containing copper alloy, zinc and lead, which is capable of separating lead from copper base of brass in high yield.
It is yet another object of the present disclosure to provide a vacuum distillation method for removing lead from brass scrap containing copper alloy, zinc and lead that provides a high degree of control over process parameters.
The above objects, as well as other objects, which will become apparent to those skilled in the art from this disclosure, are achieved by the various aspects of the invention described.
The surprising realisation of the present invention that brass scrap containing copper alloy, zinc and lead when heated under reduced pressure will vaporise a significant proportion of the zinc and lead whilst the brass or copper base of the brass is still in the solid phase. Tests have shown that all or substantially all of the Zn content and up to 2/3 of the Pb content can be removed at a temperature at which the brass is still in the solid phase. Furthermore, once the temperature is raised above the melting point of the copper base of the brass, the composition of the copper base does not change further. This observation further supports that while the brass is still in the solid phase, conclusion that most of Zn and Pb can evaporate.
The difference in the condensation temperature and pressure of Zn and Pb allows the separation of these two components during the condensation recovery process. Using a condenser assembly comprising separate condensing chambers for pure or nearly pure Zn and Pb (possibly together with some Zn), three product streams can be obtained: pure copper, a condensate consisting of pure or almost pure Zn, and a condensate consisting of a Pb-Zn mixture. For example, zn can be collected in the primary condensation chamber and a Pb-Zn mixture in the secondary condensation chamber.
As used herein, the term reduced pressure generally refers to a pressure below normal atmospheric pressure (1013.25 mbar).
According to a first aspect of the present disclosure, there is provided a method of removing lead from brass scrap, comprising:
a method of removing lead from brass scrap comprising:
-heating brass scrap containing copper alloy, zinc and lead under reduced pressure at a temperature above the boiling point of lead under said reduced pressure but below the melting point of the copper base of brass scrap under said reduced pressure, thereby evaporating lead and zinc, and
-recovering the evaporated lead and zinc by condensation.
In some embodiments, the recovering comprises separately recovering the vaporized zinc and lead by condensation.
In some embodiments, the recovering comprises recovering the vaporized zinc and lead by condensation and subsequent separation of lead from zinc.
The inventors have found that evaporation of Pb from solid brass scrap generally requires very low pressures to achieve. The reduced pressure should preferably be kept well below 100 mbar, preferably well below 50 mbar. Typically, the reduced pressure should be kept below 25 mbar, preferably below 15 mbar, more preferably below 10 mbar. In some embodiments, the reduced pressure is maintained below 10 mbar. The lower limit of reduced pressure is generally determined by practical considerations. In some embodiments, the reduced pressure is above 0.01 mbar, 0.1 mbar, 1 mbar, or above 5 mbar. In some embodiments, the reduced pressure is maintained above 0.01 mbar but below 10 mbar, above 0.1 mbar but below 10 mbar, or above 1 mbar but below 10 mbar.
Maintaining the reduced pressure during evaporation of the zinc and lead may require further pressure reduction during evaporation to compensate for the zinc and lead vapors produced, either intermittently or continuously. In some embodiments, the further pressure reduction is performed at least once to compensate for the zinc and lead vapors produced.
The temperature above the boiling point of lead under reduced pressure but below the copper-based melting point of brass scrap under reduced pressure will depend on the reduced pressure. Typically, the temperature will be below the melting point of pure copper of about 1085 ℃. In some embodiments, the temperature is in the range of 800-1100 ℃, preferably 850-1050 ℃. In some embodiments, the temperature is in the range of 900-1100 ℃, preferably 950-1050 ℃. The temperature may vary within a specified range during processing. For example, the temperature may be at the lower end of the range at the beginning of the process and increased to the upper end of the range towards the end of the process. Even though the initial temperature may in some cases be slightly above the melting point of the brass raw material, the rapid evaporation of zinc, or zinc and lead, in the brass will cause the melting point of the remaining alloy to rise to a temperature at which the material remains in solid form.
In some embodiments, the reduced pressure is maintained below 10 mbar and the temperature is in the range of 800-1100 ℃, preferably in the range of 850-1050 ℃. In some embodiments, the reduced pressure is maintained below 10 mbar and the temperature is in the range of 900-1100 ℃.
The duration of the reduced pressure heating may vary depending on a range of parameters, such as pressure, temperature, the chemical composition of the brass (including the concentration of zinc and lead in the brass), and the degree of lead removal desired. In some embodiments, heating is maintained under reduced pressure for at least 0.5 hour, preferably at least 1 hour, more preferably at least 2 hours.
The reduced pressure heating may also be carried out in two or more sequential steps at different temperatures and/or reduced pressures. Typically, the first step involves evaporating pure or nearly pure Zn at a first pressure and temperature, and the second step involves evaporating Pb or a mixture of Pb and Zn at a second pressure and temperature.
Thus, in some embodiments, the method further comprises:
a) Heating brass scrap containing copper alloy, zinc and lead at a primary reduced pressure at a temperature higher than the boiling point of zinc at the primary reduced pressure but lower than the boiling point of lead at the primary reduced pressure and lower than the melting point of copper base of brass scrap at the primary reduced pressure to evaporate zinc, and
b) The evaporated zinc is recovered by condensation,
c) Secondarily heating the brass scrap under a secondary reduced pressure at a temperature higher than the boiling point of lead under the secondary reduced pressure but lower than the melting point of the copper base of the brass scrap under the secondary reduced pressure to evaporate lead and zinc, and
d) The evaporated lead and zinc are recovered by condensation.
In some embodiments, step d) comprises separately recovering the vaporized zinc and lead by condensation.
In some embodiments, step d) comprises recovering the evaporated zinc and lead by condensation and subsequent separation of lead from zinc.
The secondary reduced pressure is preferably lower than the primary reduced pressure.
In some embodiments, said primary depressurization is higher than 10 mbar, preferably higher than 15 mbar, more preferably higher than 25 mbar. In some embodiments, the primary reduced pressure is maintained above 10 mbar. In some embodiments, the primary reduced pressure is less than 50 mbar or less than 100 mbar. In some embodiments, the primary reduced pressure may be above 50 mbar or above 100 mbar. The primary reduced pressure was below normal atmospheric pressure (1013.25 mbar).
The secondary reduced pressure is lower than the primary reduced pressure. The reduced pressure should preferably be kept well below 100 mbar, preferably well below 50 mbar. Typically, the secondary reduced pressure should be kept below 25 mbar, preferably below 15 mbar, more preferably below 10 mbar. In some embodiments, the secondary reduced pressure is maintained below 10 mbar. The lower limit of the secondary depressurization is generally determined by practical considerations. In some embodiments, the secondary reduced pressure is above 0.01 mbar, 0.1 mbar, 1 mbar, or above 5 mbar. In some embodiments, the secondary reduced pressure is maintained above 0.01 but below 10 mbar, above 0.1 but below 10 mbar, or above 1 but below 10 mbar.
The temperature above the boiling point of zinc at the primary reduced pressure but below the boiling point of lead at the primary reduced pressure and below the copper-based melting point of brass scrap at the primary reduced pressure will depend on the primary reduced pressure. In some embodiments, the temperature of the primary heating is in the range of 800-1100 ℃, preferably 850-1050 ℃. In some embodiments, the temperature of the primary heating is in the range of 900-1100 ℃, preferably 950-1050 ℃. Even though the initial temperature may in some cases be slightly above the melting point of the brass raw material, the rapid evaporation of zinc, or zinc and lead, in the brass will cause the melting point of the remaining alloy to rise to a temperature at which the material remains in solid form.
A temperature above the boiling point of lead at the secondary reduced pressure but below the melting point of the copper base of the brass scrap at the secondary reduced pressure will depend on the secondary reduced pressure. In some embodiments, the temperature of the second heating is in the range of 800-1100 ℃, preferably 850-1050 ℃. In some embodiments, the temperature of the second heating is in the range of 900-1100 ℃, preferably 950-1050 ℃.
In some embodiments, the ranges of the first and second temperatures are the same or overlap, while the ranges of the first and second pressures do not overlap.
The time for maintaining reduced pressure heating may vary depending on parameters such as pressure, temperature, the chemical composition of the brass (including the concentration of zinc and lead in the brass), and the desired degree of zinc and lead removal.
In some embodiments, the one heating at one reduced pressure is maintained for at least 0.5 hour, preferably at least 1 hour, more preferably at least 2 hours.
In some embodiments, the second heating under the second reduced pressure is maintained for at least 0.5 hour, preferably at least 1 hour, more preferably at least 2 hours.
In some embodiments, the reduced pressure heating is performed in a vacuum furnace. The vacuum furnace may preferably be provided with one or more condensation chambers for collecting evaporated Zn and Pb. In some embodiments, the vacuum furnace includes a primary condensation chamber configured to collect Zn and a secondary condensation chamber configured to collect a Pb-Zn mixture.
In some embodiments, the copper base of the brass scrap remains in a solid form throughout the lead removal process. This is advantageous because it allows more accurate control of process conditions such as pressure and temperature.
The brass scrap preferably has a relatively well-defined elemental composition. This is advantageous because it allows more accurate control of process conditions such as pressure and temperature.
In some embodiments, the brass scrap comprises at least 50wt% copper, preferably at least 55wt% copper.
In some embodiments, the brass scrap comprises at least 5wt% zinc, preferably at least 10wt% zinc.
In some embodiments, the brass scrap comprises at least 90wt% copper zinc composition, preferably at least 95wt% copper zinc composition.
In some embodiments, the brass scrap comprises at least 0.1wt% lead, preferably at least 0.5wt% and more preferably at least 1wt% lead.
In some embodiments, the brass scrap comprises 60-80wt% copper, 20-40wt% zinc, at least 90wt% copper-zinc composition, and 0.1-10wt% lead.
In some embodiments, at least 10% of the Pb content of the brass scrap is removed by the method. In some embodiments, at least 25% of the Pb content of the brass scrap is removed by the method. In some embodiments, at least 50% of the Pb content of the brass scrap is removed by the method.
While the invention has been described with reference to various exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or feature to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Examples
A total of six tests were performed in a vacuum induction furnace. The furnace lid has been modified to have a channel for directing the evaporated off-gas to a condenser system to capture the evaporated Zn and Pb.
Experimental apparatus:
the tests were divided into two batches of three tests each. Table 1 shows the parameters of each test. The brass is diluted with brass scrap to reduce the zinc content in the system to avoid overloading the zinc condenser system.
TABLE 1 test parameters for vacuum induction furnace deleading tests
The experimental procedures for each test performed are described in detail below.
PBV1:
In this test, the material is completely melted before the pressure is reduced. Eyes of a personThe target temperature is 1200 ℃ N 2 The bottom gas feed was initially 5Nl/min. Once all the material melted, the pressure was reduced to about 100 mbar. Due to excessive boiling, the gas feed was reduced to 2.8Nl/min and the pressure was increased to 270 mbar. The hold time was 4 hours from when all the material had melted. Samples were collected after 1 hour and before discharge.
PBV2:
In this test, the pressure was reduced to 5 mbar before melting began. N is a radical of hydrogen 2 The bottom gas feed was set at 2.8Nl/min. About 50 minutes after the start of the test, the material began to give off white smoke, probably Zn (g). The material immediately started boiling as soon as it melted, forcing the pressure to increase to 300 mbar. Samples were collected intermittently. The hold time was 4 hours from when all the material had melted. Once this time has elapsed, the pressure is reduced to 150 mbar in spite of the increase in boiling point, in order to increase the lead removal effect. The melt was held at 150 mbar for 1 hour, then final sampling and discharge were performed.
PBV3:
The purpose of this test was to check the Pb/Zn removal at high temperature but not molten. The plan was to heat the brass sample to near 1000 c (near the melting point of brass) but not melt and hold for 2 hours, and then melt and hold the material for an additional 2 hours. To minimize boiling, no bottom gas feed was used in this test. As indicated by optical inspection, the pressure was reduced to 5 mbar and the temperature was increased to slightly below the melting point. The temperature was maintained for 2 hours, during which time white smoke was emitted. Since the material is in a solid state, sampling cannot be performed. The test was terminated after the first 2 hours due to furnace short circuit. The final samples were taken from cast brass.
PBV4:
This test was conducted to investigate the Zn/Pb removal observed in earlier tests for solid phase brass. The test used the same conditions as for PBV3, i.e. the material was kept just below the melting point for 2 hours, then melted and discharged. Samples were collected prior to discharge.
PBV5:
The test plan was performed as for testing PBV3 and PBV4, but the retention time for solid phase Zn/Pb removal was longer. Unfortunately, after about 2.5 hours, most of the material had melted. At this point, the temperature is raised in order to completely melt the material, similar to the initial plan for testing PBV 3. After 30 minutes, the test was terminated again by short-circuiting. Exhaust channel temperature and pressure measurements were observed to be very similar to the test PBV4, indicating that these parameters can be used to control the process. Samples were collected prior to discharge.
PBV6:
This test attempted to complete the original plan for testing PBV3 by holding the temperature at a temperature slightly below the melting point of brass for 2 hours, then melting the material and holding it for an additional 2 hours. The exhaust gas channel temperature and pressure measurements and knowledge obtained in the previous tests for PBV4 and PBV5 were used to control the process. The first sample was collected after the material had melted and then sampled approximately every 40 minutes.
Chemical analysis:
chemical analysis of the test samples is shown in table 2. In all cases, the Cu content was increased, while both Pb and Zn contents are reduced. It is also evident that all Zn and most of Pb in the solid phase can be removed. Furthermore, complete separation of zinc and copper can only be achieved with tests (PBV 3-6) in which the pressure is sufficiently low.
The condensate from the test PBV4-6 was analyzed as shown in Table 3. As expected, the condensate has Zn as the main component, and also trace amounts of Pb and several other trace elements.
TABLE 2 chemical analysis of copper alloys during and after vacuum treatment
*0min = sample melting
TABLE 3 chemical analysis of Zn collected in condenser
| Sample (I) | Zn | Pb |
| PBV4-Zn | 97.87 | 1.41 |
| PBV5-Zn | 96.35 | 1.94 |
| PBV6-Zn | 98.97 | 0.93 |
Mass balance and lead removal:
table 4 shows the mass balance of Cu and Zn in all tests. The generation value of Zn does not include a material forming a coating in a furnace, or a material condensed in an exhaust gas passage.
Table 4. Mass balance of vacuum induction furnace test. All values are in kg
| PBV1 | PBV2 | PBV3 | PBV4 | PBV5 | PBV6 | |
| Cu Feeding in | 25.7 | 38.7 | 25.7 | 25.7 | 28.8 | 28.1 |
| Zn Is thrown in | 2.5 | 2.5 | 2.5 | 2.5 | 2.5 | 2.5 |
| Total of Is thrown in | 28.2 | 41.2 | 28.2 | 28.2 | 31.3 | 30.6 |
| Cu Generating | 25.5 | 38.1 | 26.3 | 25.0 | 27.8 | 26.2 |
| Zn Generating | 1.4 | 0.6 | 1.3 | 0.9 | 0.6 | 2.0 |
| Total of Generating | 26.9 | 38.6 | 27.6 | 26.1 | 28.5 | 28.3 |
The best Pb removal was achieved in the PBV6 test. In this test, the degree of Pb removal was about 65%.
The Pb removal degree was calculated as follows:
Pb is thrown in = weight Is thrown in *[Pb] Is thrown in ＝28.4*0.0068＝0.192g
Pb Generating = weight Generating *[Pb] Brass formation ＝26.32*0.0026＝0.068g
Except Pb =100 (Pb) Is thrown in –Pb Generating )/Pb Zxfoom ＝100*(0.192–0.068)/0.192＝65％。
Claims (22)
1. A method of removing lead from brass scrap comprising:
-heating under reduced pressure brass scrap containing copper alloy, zinc and lead at a temperature above the boiling point of lead under said reduced pressure but below the melting point of the copper base of brass scrap under said reduced pressure, thereby evaporating lead and zinc, and
-recovering the evaporated lead and zinc by condensation.
2. The method of claim 1, wherein the recovering comprises separately recovering the vaporized zinc and lead by condensation.
3. The method of claim 1, wherein the recovering comprises recovering the vaporized zinc and lead by condensation and subsequent separation of lead from zinc.
4. The method according to any one of the preceding claims, wherein the reduced pressure is maintained below 10 mbar.
5. The method according to any of the preceding claims, wherein the temperature is in the range of 800-1100 ℃, preferably in the range of 850-1050 ℃.
6. The process according to any one of the preceding claims, wherein the heating is maintained under reduced pressure for at least 1 hour, preferably at least 2 hours.
7. The method of claim 1, the method comprising:
a) Heating brass scrap containing copper alloy, zinc and lead at a primary reduced pressure at a temperature higher than the boiling point of zinc at the primary reduced pressure but lower than the boiling point of lead at the primary reduced pressure and lower than the melting point of copper base of brass scrap at the primary reduced pressure to evaporate zinc, and
b) The evaporated zinc is recovered by condensation,
c) Secondarily heating the brass scrap under a secondary reduced pressure at a temperature higher than the boiling point of lead under the secondary reduced pressure but lower than the melting point of the copper base of the brass scrap under the secondary reduced pressure to evaporate lead and zinc, and
d) The evaporated lead and zinc are recovered by condensation.
8. The method of claim 7, wherein step d) comprises separately recovering the evaporated zinc and lead by condensation.
9. The method of claim 7, wherein step d) comprises recovering the evaporated zinc and lead by condensation and subsequent separation of lead from zinc.
10. The method according to any one of claims 7-9, wherein the primary reduced pressure is maintained above 10 mbar.
11. The method of any of claims 7-10, wherein the secondary reduced pressure is maintained below 10 mbar.
12. The method according to any one of claims 7-11, wherein the temperature of the primary heating is in the range of 800-1100 ℃, preferably in the range of 850-1050 ℃.
13. The method according to any one of claims 7-12, wherein the temperature of the secondary heating is in the range of 800-1100 ℃, preferably in the range of 850-1050 ℃.
14. The method according to any one of claims 7 to 13, wherein the one heating under the one reduced pressure is maintained for at least 1 hour, preferably at least 2 hours.
15. The method of any one of claims 7-14, wherein the second heating under the second reduced pressure is maintained for at least 1 hour, preferably at least 2 hours.
16. A method according to any preceding claim, wherein the heating under reduced pressure is carried out in a vacuum oven.
17. A process according to any one of the preceding claims, wherein the copper base of the brass scrap remains in solid form throughout the lead removal process.
18. A method according to any preceding claim, wherein the brass scrap comprises at least 50wt% copper, preferably at least 55wt% copper.
19. A method according to any preceding claim, wherein the brass scrap comprises at least 5wt% zinc, preferably at least 10wt% zinc.
20. A process according to any preceding claim, wherein the brass scrap comprises at least 90wt% copper zinc composition, preferably at least 95wt% copper zinc composition.
21. A method according to any preceding claim, wherein the brass scrap comprises at least 0.1wt% lead, preferably at least 0.5wt% and more preferably at least 1wt% lead.
22. A method according to any preceding claim, wherein the brass scrap comprises 60-80wt% copper, 20-40wt% zinc, at least 90wt% copper zinc composition and 0.1-10wt% lead.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1951540-2 | 2019-12-20 | ||
| SE1951540A SE543879C2 (en) | 2019-12-20 | 2019-12-20 | Method for removing lead from brass |
| PCT/EP2020/086741 WO2021122974A1 (en) | 2019-12-20 | 2020-12-17 | Method for removing lead from brass |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115151664A true CN115151664A (en) | 2022-10-04 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202080088414.8A Pending CN115151664A (en) | 2019-12-20 | 2020-12-17 | Method for removing lead from brass |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP4077749A1 (en) |
| CN (1) | CN115151664A (en) |
| SE (1) | SE543879C2 (en) |
| WO (1) | WO2021122974A1 (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1080325A (en) * | 1992-05-20 | 1994-01-05 | 奥托库普研究有限公司 | Produce the method for volatile metals such as zinc, lead and cadmium by sulfidic materials |
| CN101343694A (en) * | 2008-08-15 | 2009-01-14 | 昆明理工大学 | Dezincing smelting method for waste mixed aluminum alloy containing zinc |
| CN101353726A (en) * | 2008-09-19 | 2009-01-28 | 中南大学 | Method for separating lead platinum alloy by vacuum distillation |
| JP2009263728A (en) * | 2008-03-17 | 2009-11-12 | Hyo Sok Ahn | Reduction treatment method and reduction treatment apparatus |
| JP2011062644A (en) * | 2009-09-17 | 2011-03-31 | Hyo Sok Ahn | Method for recovering valuable resource from disposed matter |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4606760A (en) * | 1985-05-03 | 1986-08-19 | Huron Valley Steel Corp. | Method and apparatus for simultaneously separating volatile and non-volatile metals |
| JPH0978148A (en) * | 1995-09-14 | 1997-03-25 | Ogihara Ekorojii Kk | Disposal method by destructing waste structure |
| CN103397200B (en) * | 2013-08-23 | 2015-06-10 | 阳谷祥光铜业有限公司 | Method for removing lead, zinc, arsenic, antimony, bismuth and tin from copper matte |
-
2019
- 2019-12-20 SE SE1951540A patent/SE543879C2/en unknown
-
2020
- 2020-12-17 WO PCT/EP2020/086741 patent/WO2021122974A1/en active Search and Examination
- 2020-12-17 EP EP20829531.1A patent/EP4077749A1/en active Pending
- 2020-12-17 CN CN202080088414.8A patent/CN115151664A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1080325A (en) * | 1992-05-20 | 1994-01-05 | 奥托库普研究有限公司 | Produce the method for volatile metals such as zinc, lead and cadmium by sulfidic materials |
| JP2009263728A (en) * | 2008-03-17 | 2009-11-12 | Hyo Sok Ahn | Reduction treatment method and reduction treatment apparatus |
| CN101343694A (en) * | 2008-08-15 | 2009-01-14 | 昆明理工大学 | Dezincing smelting method for waste mixed aluminum alloy containing zinc |
| CN101353726A (en) * | 2008-09-19 | 2009-01-28 | 中南大学 | Method for separating lead platinum alloy by vacuum distillation |
| JP2011062644A (en) * | 2009-09-17 | 2011-03-31 | Hyo Sok Ahn | Method for recovering valuable resource from disposed matter |
Also Published As
| Publication number | Publication date |
|---|---|
| EP4077749A1 (en) | 2022-10-26 |
| SE1951540A1 (en) | 2021-06-21 |
| SE543879C2 (en) | 2021-09-14 |
| WO2021122974A1 (en) | 2021-06-24 |
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