A kind of method of copper in Mixed Microbes leaching discarded printed circuit boards
The application is Application No. 201310457250.3, and the applying date is September in 2013 30, and invention and created name is
The divisional application of the application for a patent for invention of " method of copper in Mixed Microbes leaching discarded printed circuit boards ".
Technical field
The present invention relates to a kind of recovery method of copper in discarded printed circuit boards, and in particular to a kind of Mixed Microbes leaching is discarded
The method of copper in printed circuit board (PCB).
Background technology
With information technology fast development, electron wastes (Waste Electric and Electronic
Equipment, WEEE) yield constantly rises, and discarded printed circuit boards (Printed Circuit Boards, PCBs) are made
It is WEEE important components, usually contains 40% or so metal, wherein metallic copper is main composition, and content is up to 20%~30%.
According to estimates, China needs treatment PCBs to increase about more than 500,000 tons and with 22% speed every year.If realizing discarded PCB
Treatment and recovery, can solve problem of environmental pollution, can realize that metal is effectively reclaimed again, by holding to China's PCBs industries
Supervention opens up important in inhibiting.
The method for extracting copper from discarded printed circuit boards at present mainly has Physical, chemical method and bioanalysis.Physical
Evaluation index is higher in terms of regenerated resources effect, the friendly property of environment, commercial Application rate, but the plant equipment for being used is invested
Greatly, energy-output ratio is high, maintenance cost is high, thus economic feasibility is relatively poor;And be difficult between metal separate in product.
Chemical method is broadly divided into pyrogenic process and wet method, although pyrogenic process has the advantages that simple, the convenient and rate of recovery is high, can produce simultaneously
The shortcomings of evil gas, discharge a large amount of scum silica frost;Wet method have waste gas discharge it is few, extract copper after residue be easily handled and technique letter
Single the advantages of, but copper extraction rate is low and leachate and residue have toxicity.Therefore will pollution less, low cost, reaction condition temperature
The bioanalysis of sum has unique advantage in being applied to discarded printed circuit boards metal recovery.
The features such as copper in bioleaching PCBs has safe and clean, efficient, it has also become domestic and international study hotspot.At present
Using most common microorganism be Acidithiobacillus thiooxidans (A.t) and Thiobacillus ferrooxidans (A. f)。
Such as Zhou Peiguo etc.(The such as Zhou Peiguo, Zheng Zheng, Peng Xiaocheng copper leaching from printed circuit board by Thiobacillus ferrooxidans and process
The Changeement of middle iron《Environmental Pollution and Control》;2007(02):119~122)It is discarded using Thiobacillus ferrooxidans leaching
Circuit board powder(Copper mass fraction is 10.4%)In copper, when waste printed circuit board powder addition be 100 g/L when, 15d or so
Copper extraction rate is about 90%.
The A of Chinese patent literature CN 1948524(Application number 200610097382.X)Disclose a kind of waste printed circuit board comprehensive
Close recycling processing method, in culture medium solution be inoculated with by domestication Thiobacillus ferrooxidans, the micro- spirillum of ferrous oxide or
Sulfolobus solfataricus bacterium solution is cultivated, and after eliminating the circuit board substrate crushing of various components, is added thereto to culture and is obtained
Bacterium solution, leaching 10~15 days under the speed of 120~160r/min, separate liquid and solid;Liquid copper extractant
Extracted, then be stripped and electrolytic deposition obtains metallic copper.
The above method is to carry out bioleaching using single microorganism, and its metal extraction time is long, and leaching efficiency is low.
Research shows that copper is current most efficient method in Mixed Microbes leaching PCBs.
Such as SADIA etc.( Sadia I, Munir AA, Shahida BN, Afzal Ghauri M.
Bioleaching of metals from electronic scrap by moderately thermophilic
acidophilic bacteria. Hydrometallurgy 2007;88:180–8.)It is useless using the leaching of middle temperature acidophilus Mixed Microbes
Abandon circuit board powder(Copper mass fraction is 8.5%)In metal, when waste printed circuit board powder addition be 10g/L when, after 18d
The extraction rate of copper is 89%.But although the Mixed Microbes leaching method has used Mixed Microbes, but leaching time is long, extraction rate not
Such as a kind of efficiency high of bacterial leaching.When this is due to multi strain co cultivation, there is provided which type of nutritional substrate and external condition make
Mixed Microbes energy uniform growth, is suppressed phenomenon most important from another bacterium without a kind of excessive multiplication.Additionally, thin
Bacterium leaching copper ability is closely related with its own growth metabolism, bacteria growing inhibiting is understood in PCBs adding procedures and then causes copper to soak
Ability decline is taken, thus how to optimize PCBs addition manners is the another key factor for realizing copper in the efficient leaching PCBs of Mixed Microbes
One of.
The content of the invention
The technical problems to be solved by the invention are to provide a kind of multi strain co cultivation method and discarded print are efficiently leached with it
The method of copper in printed circuit board.
The technical scheme for realizing the object of the invention is a kind of method of copper in Mixed Microbes leaching discarded printed circuit boards, including
Following steps:
1. the pretreatment of discarded printed circuit boards;The discarded printed circuit boards PCBs that electronic component will have been removed is crushed and ground
Clay into power, the discarded printed circuit boards powder sieving that grinding is obtained, collection is treated by the discarded printed circuit boards powder of sieve aperture
Treatment.
2. tamed strain;By Acidithiobacillus ferrooxidans strain GFA.ferrooxidansAnd Acidithiobacillus thiooxidansA.thiooxidansResistance to Cu is carried out respectively2+Domestication culture, domestication end respectively obtain resistance to 100~200mmol/L Cu2+Ring
BorderA.ferrooxidansWithA.thiooxidansIt is stand-by.
3. multi strain co cultivation;2. step is tamed what is obtained after cultivatingA.ferrooxidansWithA.thiooxidansPress
Multi strain co cultivation is carried out in multi strain co cultivation liquid for 1: 1.5~2.5 according to inoculum concentration, and it is 1.5~1.8 to cultivate initial pH, is mixed
It is the 10%~20% of multi strain co cultivation liquid product to close bacterium inoculum concentration.
4. the addition of discarded printed circuit boards powder;Treat that 3. the multi strain co cultivation time reaches 40~55 hours, first to step
It is secondary add step 1. to pre-process the discarded PCBs powder for obtaining in the multi strain co cultivation system of 40~55 hours to have cultivated, then
Every 20~25 hours again to multi strain co cultivation system in add step 1. to pre-process the discarded PCBs powder that obtains, after once
The discarded PCBs powder for adding once increases by 1~3g/L, the discarded PCBs powder added in 1L multi strain co cultivation systems compared to preceding
The gross mass at end is 28g~36g;When discarded PCBs powder finishes bacterium incubation time arrival 175h~200h to be mixed, Mixed Microbes
Leaching reaction terminates;Reacted mixed material is centrifuged, upper strata leachate is collected.
5. post-process;The leachate that 4. step obtains is extracted with copper extractant, for the cupric extract for obtaining,
It is stripped with strippant;Then the cupric strip liquor that will be obtained is transferred in electrolytic cell and carries out electrodeposition and obtain copper, completes
The recovery of copper in discarded printed circuit boards.
Above-mentioned steps 3. multi strain co cultivation when, the content of each component is in multi strain co cultivation liquid used:Elemental sulfur 4.0~
6.5g/L, 3.5~4.5g/L of ammonium sulfate, the g/L of dipotassium hydrogen phosphate 0.45~0.65, bitter salt 0.45~0.65
G/L, the g/L of potassium chloride 0.1~0.15, calcium nitrate 0.008~0.015 g/L, 15~18g/L of green vitriol, chlorine
Change the g/L of calcium 0.10~0.18;Multi strain co cultivation liquid solute is water.
As preferred, step 3. multi strain co cultivation when, the content of each component is in multi strain co cultivation liquid used:Simple substance
5.2~5.6g/L of sulphur, 3.5~4.5g/L of ammonium sulfate, the g/L of dipotassium hydrogen phosphate 0.45~0.65, bitter salt 0.45
~0.65 g/L, the g/L of potassium chloride 0.1~0.15, the g/L of calcium nitrate 0.008~0.015, green vitriol 17~
17.5g/L, the g/L of calcium chloride 0.10~0.18;Multi strain co cultivation liquid solute is water.
When 4. above-mentioned steps discard the addition of PCBs powder, treat that 3. the multi strain co cultivation time reaches 40~55 hours step, to
1. addition step pre-processes the discarded PCBs powder for obtaining in having cultivated the multi strain co cultivation system of 40~55 hours, the mixing per 1L
The discarded PCBs powder of 4g~6g is added in bacterium cultivating system, the discarded PCBs powder of addition proceeds by Mixed Microbes leaching reaction;
After bacterium to be mixed continues to cultivate 20~25 hours, the discarded PCBs for obtaining 1. is pre-processed to second addition step in cultivating system
Powder, per 1L multi strain co cultivation systems in add the discarded PCBs powder of 6g~8g, the discarded PCBs powder of addition proceeds by mixed
Close bacterium leaching reaction;After bacterium to be mixed continues to cultivate 20~25 hours, 1. pre-processed to step is added in cultivating system for the third time
The discarded PCBs powder for obtaining, adds the discarded PCBs powder of 8g~10g, the discarded PCBs of addition in every 1L multi strain co cultivation systems
Powder proceeds by Mixed Microbes leaching reaction;After bacterium to be mixed continues to cultivate 20~25 hours, add to the 4th time in cultivating system
Plus 1. step pre-processes the discarded PCBs powder for obtaining, the discarded PCBs powder of 10g~12g is added in every 1L multi strain co cultivation systems
End, discarded PCBs powder addition is finished.
Above-mentioned steps are 2.A.ferrooxidansWhen carrying out domestication culture, will be carried from the aeration tank of municipal sewage plant
The sludge enrichment culture for taking, is then peeled off purifying and obtainingA.ferrooxidans;WillA.ferrooxidansIn 9K nutrient solutions
It is middle to cultivate to logarithmic phase;It is 10%~20% according to strain inoculum concentration(Volume ratio v/v), draw above-mentioned bacterium solution and be transferred to Cu2+It is dense
Spend in the nutrient solution for 10mmol/L;It is 10%~20% according to strain inoculum concentration after culture to logarithmic phase(Volume ratio v/v), inhale
Take above-mentioned bacterium solution and be transferred to Cu2+Concentration for 20mmol/L nutrient solution in cultivate to logarithmic phase;Aforesaid operations are repeated, is often increased
The domestication of generation bacterial strain, Cu in nutrient solution used2+Concentration increase 10mmol/L compared to previous generation, so as to obtaining 100~
200mmol/L Cu2+Cultivated in environment to logarithmic phaseA.ferrooxidans。
Above-mentioned steps are 2.A.thiooxidansWhen carrying out domestication culture, will be carried from the aeration tank of municipal sewage plant
The sludge enrichment culture for taking, is then peeled off purifying and obtainingA.thiooxidans;WillA.thiooxidansTrained in nutrient solution
Support to logarithmic phase;It is 10%~20% according to strain inoculum concentration(Volume ratio v/v), draw above-mentioned bacterium solution and be transferred to Cu2+Concentration be
In the nutrient solution of 10mmol/L;It is 10%~20% according to strain inoculum concentration after culture to logarithmic phase(Volume ratio v/v), in absorption
State bacterium solution and be transferred to Cu2+Concentration for 20mmol/L nutrient solution in cultivate to logarithmic phase;Aforesaid operations are repeated, often increases a generation
The domestication of bacterial strain, Cu in nutrient solution used2+Concentration increase 10mmol/L compared to previous generation, so as to obtaining 100~
200mmol/L Cu2+Cultivated in environment to logarithmic phaseA.thiooxidans。
The present invention has positive effect:
(1)The nutritional substrate and condition of culture of offer make Acidithiobacillus ferrooxidans strain GF when the present invention carries out multi strain co cultivation
(Acidithiobacillus.ferrooxidans, A.ferrooxidans) and Acidithiobacillus thiooxidans
(Acidithiobacillus. thiooxidans, A.thiooxidans) two kinds of bacterium energy uniform growths, it is a kind of without occurring
Bacterium excessive multiplication and another bacterium is suppressed phenomenon.Additionally, present invention optimizes the addition manner of discarded PCBs powder, using preceding
The mode of low rear multiple spot addition high, on the basis of discarded PCBs additions are improved, copper extraction rate is significantly improved and thalli growth
Suppressed degree is relatively small.
(2)The present invention uses multi strain co cultivation, and two kinds of bacterium of pH of nutrient solution need not be adjusted during culture with regard to energy uniform growth,
Simultaneously a large amount of sulfuric acid and Fe are generated during two kinds of bacteria growings3+For the leaching of copper in later stage discarded PCBs powder, whole process efficiency
High, save energy.
(3)The present invention is right before bioleaching is carried outA.ferrooxidansWithA.thiooxidansCarry out at resistance to copper
Reason, significantly improves two kinds of resistance to copper of bacterium, promotes the leaching of copper in discarded PCBs powder.
(4)) whole process process is simple of the invention, economy, environmental protection, the need for meeting recycling economy development, with good
Good prospects for commercial application.
Specific embodiment
(Embodiment 1)
The method of copper is comprised the following steps in the Mixed Microbes leaching discarded printed circuit boards of the present embodiment:
1. the pretreatment of discarded printed circuit boards.The discarded printed circuit boards PCBs that electronic component will have been removed is crushed and ground
Clay into power, the discarded PCBs powder that grinding is obtained crosses 100 μm~200 μm of sieve aperture(What grinding was obtained in the present embodiment is discarded
Printed circuit board (PCB) powder crosses 100 μm of sieve aperture), collect pending by the discarded PCBs powder of sieve aperture.
After the ground sievings of discarded PCBs of the present embodiment treatment, its major metal content is analyzed,
Major metal content is as shown in table 1 below:
Major metal content in the discarded printed circuit boards powder of table 1
2. tamed strain.
(1)Acidithiobacillus ferrooxidans strain GF(A.ferrooxidans)Domestication.By from the aeration of municipal sewage plant
The sludge enrichment culture extracted in pond, is then peeled off purifying and obtainingA.ferrooxidans;WillA.ferrooxidansIn 9K
Cultivated in nutrient solution to logarithmic phase, now bacteria concentration rises to 10 in bacterium solution7Cell/mL.
9K nutrient solutions used include per 1L:44.7g FeSO4·7H2O, 3.0g (NH4)2SO4, 0.5g K2HPO4,
0.5g MgSO4·7H2O, 0.1g KCl, 0.01g Ca (NO3)2, the pH value of nutrient solution is 2.00.
It is 10%~20% according to strain inoculum concentration(Volume ratio v/v), draw above-mentioned bacterium solution and be transferred to and added 100mL fresh
In the 250mL conical flasks of nutrient solution, in 32 DEG C of temperature, shaking speed is 120~200r/min(It is 150 r/ in the present embodiment
min)Under the conditions of cultivate to logarithmic phase complete the first generation domestication.First generation domestication is usedA.fNutrient solution remaining cultivated with above-mentioned 9K
Liquid phase is same, and difference is that increased Cu in nutrient solution2+, Cu in nutrient solution2+Concentration be 10mmol/L.
It is 10%~20% according to strain inoculum concentration(Volume ratio v/v), draw the bacterium solution after the domestication of the above-mentioned first generation to fresh
Cultivated in nutrient solution to logarithmic phase, Cu in this nutrient solution used2+Concentration rise to 20mmol/L.
Repeat aforesaid operations, bacterium solution is transferred to successively containing 30,40,50,60,70,80,90,100,110,120,130,
140th, 150,160,170,180,190 and 200mmol/L Cu2+Fresh medium in tame culture, culture terminate after, centrifugation
Removal supernatant, collects the Cu for being resistant to 200 mmol/L2+The thalline of concentration to put refrigerator stand-by.
During above-mentioned domestication, often increase the domestication of generation bacterial strain, Cu in nutrient solution used2+Concentration compare previous generation
Increase 10mmol/L.Due to Cu2+Concentration is raised, so cultivating to logarithmic phase(Bacteria concentration is 107Cell/mL)Required time meeting
It is more and more long.According to treatment powder situation, by Acidithiobacillus ferrooxidans strain GF 100 mmol/L Cu2+Concentration under cultivate
Domestication can also be stopped after to logarithmic phase, so as to obtain the Cu of resistance to 100 mmol/L2+ConcentrationA.ferrooxidans。
(2)Acidithiobacillus thiooxidans(A.thiooxidans)Domestication.By from the aeration tank of municipal sewage plant
The sludge enrichment culture of extraction(Sewage Plant processes sewage using A2/O), it is then peeled off purifying and obtainingA.thiooxidans;WillA.thiooxidansCultivated in nutrient solution to logarithmic phase, now bacteria concentration rises to 10 in bacterium solution7Cell/mL.
Nutrient solution used includes per 1L:10.0g S0, 0.5g (NH4)2SO4, 0.25g K2HPO4, 0.25g
MgSO4·7H2O, 0.02g CaCl2·2H2O;The pH value of nutrient solution is 4.00.
It is 10%~20% according to strain inoculum concentration(Volume ratio v/v), draw above-mentioned bacterium solution and be transferred to and added 100mL fresh
In the 250mL conical flasks of nutrient solution, in 32 DEG C of temperature, shaking speed is 120~200r/min(It is 150 r/ in the present embodiment
min)Under the conditions of cultivate to logarithmic phase obtain the first generation domestication Acidithiobacillus thiooxidans.
First generation domestication is usedA.tRemaining is identical with above-mentioned nutrient solution for nutrient solution, and difference is first generation domestication institute
WithA.tCu is increased in nutrient solution2+, Cu in nutrient solution2+Concentration be 10mmol/L.
According to(1)Middle Acidithiobacillus ferrooxidans strain GF(A.f)Acclimation method, bacterium solution is transferred to successively containing 20,30,40,
50th, 60,70,80,90,100,110,120,130,140,150,160,170,180,190 and 200mmol/L Cu2+It is fresh
Culture to logarithmic phase is tamed in nutrient solution, after culture terminates, centrifugation removal supernatant collects the Cu for being resistant to 200 mmol/L2+'s
It is stand-by that the thalline of concentration puts refrigerator.
According to the powder situation for the treatment of, willA.thiooxidansIn the Cu of 100 mmol/L2+Concentration under cultivate to logarithm
Domestication can also be stopped after phase, so as to obtain the Cu of resistance to 100 mmol/L2+ConcentrationA.thiooxidans。
During i.e. above-mentioned domestication, often increase the domestication of generation bacterial strain, Cu in nutrient solution used2+Concentration compare upper one
In generation, increases 10mmol/L.Due to Cu2+Concentration is raised, so cultivating to logarithmic phase(Bacteria concentration is 107Cell/mL)Required time
Can be more and more long.
3. multi strain co cultivation.2. step is tamed what is obtained after cultivatingA.ferrooxidansWithA.thiooxidansPress
According to inoculum concentration is 1: 1.5~2.5(It is 1: 2 in the present embodiment)Multi strain co cultivation is carried out in multi strain co cultivation liquid, culture is just
Beginning pH is 1.5~1.8(It is 1.6 in the present embodiment), Mixed Microbes inoculum concentration is the 10%~20% of multi strain co cultivation liquid product.Mixing
32 DEG C of temperature is controlled when bacterium is cultivated, shaking speed is 120~200r/min(It is 150 r/min in the present embodiment).
The content of each component is in multi strain co cultivation liquid:4.0~6.5g/L of elemental sulfur, 3.5~4.5g/L of ammonium sulfate,
The g/L of dipotassium hydrogen phosphate 0.45~0.65, the g/L of bitter salt 0.45~0.65, the g/L of potassium chloride 0.1~0.15, nitre
Sour calcium 0.008~0.015 g/L, 15~18g/L of green vitriol, the g/L of calcium chloride 0.10~0.18;Multi strain co cultivation
Liquid solute is water, and pH is 1.5~1.8.
The content of each component is in multi strain co cultivation liquid used in the present embodiment:Elemental sulfur 5.5g/L, ammonium sulfate 4.0
G/L, the g/L of dipotassium hydrogen phosphate 0.5, the g/L of bitter salt 0.5, the g/L of potassium chloride 0.1, calcium nitrate 0.01 g/L, seven
The g/L of ferrous sulfate hydrate 17.2, calcium chloride 0.13 g/L, pH are 1.6.
4. the addition of discarded printed circuit boards powder.Treat that 3. the multi strain co cultivation time reaches 48 hours step, to culture
Step is added 1. to pre-process the discarded PCBs powder for obtaining in the multi strain co cultivation system of 48 hours, per 1L multi strain co cultivation systems
The discarded PCBs powder of middle addition 4g, the discarded PCBs powder of addition proceeds by Mixed Microbes leaching reaction.
Bacterium to be mixed is cultivated during to 72 hours, continues 1. to pre-process the discarded PCBs for obtaining to addition step in cultivating system
Powder, adds the discarded PCBs powder of 6g in every 1L multi strain co cultivation systems, the discarded PCBs powder of addition proceeds by Mixed Microbes
Leaching reaction.
Bacterium to be mixed is cultivated during to 96 hours, continues 1. to pre-process the discarded PCBs for obtaining to addition step in cultivating system
Powder, adds the discarded PCBs powder of 8g in every 1L multi strain co cultivation systems, the discarded PCBs powder of addition proceeds by Mixed Microbes
Leaching reaction.
Bacterium to be mixed is cultivated during to 120 hours, continues 1. to pre-process obtain discarded to adding step in cultivating system
PCBs powder, per 1L multi strain co cultivation systems in add the discarded PCBs powder of 10g, the discarded PCBs powder of addition proceeds by mixed
Close bacterium leaching reaction.
Bacterium to be mixed continues to cultivate to 175h~200h(It is 180h in the present embodiment)When, Mixed Microbes leaching reaction terminates;
Cu, Ni, Zn, Pb leaching rate are respectively 97.3%, 92.5%, 93.4%, 89.6% in measuring discarded printed circuit boards powder.
Reacted mixed material is centrifuged, upper strata leachate is collected.Lower floor's solid can conduct after treatment
Construction material.
5. post-process.The leachate that 4. step obtains is extracted with copper extractant, for the cupric extract for obtaining,
It is stripped with strippant;Then the cupric strip liquor that will be obtained is transferred in electrolytic cell and carries out electrodeposition and obtain copper, completes
The recovery of copper in discarded printed circuit boards.
Anode is done using titanium plate during electrodeposition, copper coin does negative electrode.Control voltage is 2.0V, and current density is 350A/m2, pH value
It is 3, pole span is 1cm, the time is 3h, and temperature is 10 DEG C.
Copper extractant used is 2- hydroxyl -5- dodecyl diphenyl-ketoximes, and strippant is waste solution of copper electrolysis.
The rate of recovery of electro deposited copper is 99%.Reclaim copper and can reach national GB/T 6516-1997 standards.
In order to keep the basicly stable of electrodeposition condition, electrodeposition solution will constantly be circulated.The present embodiment is done using titanium plate
Anode can expeditiously deliver current to electrolyte and for anion electric discharge so that electrodeposition efficiency is improved.In addition, electrodeposition
The sulfuric acid produced during copper, recyclable recycling.
Two kinds of bacterium of pH of nutrient solution need not be adjusted during multi strain co cultivation of the present invention with regard to energy uniform growth, while two kinds of bacterium lifes
A large amount of sulfuric acid and Fe are generated when long3+For the leaching of copper in later stage discarded PCBs powder, whole process efficiency high, save energy.
In addition, present invention optimizes the addition manner of discarded PCBs powder, it is discarded improving by the way of the addition of low early and high after multiple spot
On the basis of PCBs powder additions, copper extraction rate is significantly improved and the suppressed degree of thalli growth is relatively small.
(Embodiment 2 is to embodiment 6)
In embodiment 2 to the Mixed Microbes leaching discarded printed circuit boards of embodiment 6 method of copper remaining with the phase of embodiment 1
Together, difference is:Step 3. multi strain co cultivation when multi strain co cultivation liquid used in each component content and step 4.
The addition time of discarded printed circuit boards powder and addition, are specifically shown in table 2 below and table 3.
The step of table 2 3. multi strain co cultivation when multi strain co cultivation liquid used in each component content
The step of table 3 4. the addition time of discarded printed circuit boards powder and addition
Note:Added described in upper table the time refer to after cultivating since the step 3. Mixed Microbes how many hours when carry out powder addition
Time;The addition refers to the weight of the discarded printed circuit boards powder added in every 1L multi strain co cultivations system, single
Position for gram.