CN111409212B - Waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment - Google Patents
Waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment Download PDFInfo
- Publication number
- CN111409212B CN111409212B CN201910013223.4A CN201910013223A CN111409212B CN 111409212 B CN111409212 B CN 111409212B CN 201910013223 A CN201910013223 A CN 201910013223A CN 111409212 B CN111409212 B CN 111409212B
- Authority
- CN
- China
- Prior art keywords
- flotation
- calcium hydroxide
- plastic
- mixed plastic
- plastics
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 229920003023 plastic Polymers 0.000 title claims abstract description 187
- 239000004033 plastic Substances 0.000 title claims abstract description 187
- 238000005188 flotation Methods 0.000 title claims abstract description 134
- 238000000926 separation method Methods 0.000 title claims abstract description 63
- 239000002699 waste material Substances 0.000 title claims abstract description 42
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 title claims abstract description 36
- 239000000920 calcium hydroxide Substances 0.000 title claims abstract description 23
- 229910001861 calcium hydroxide Inorganic materials 0.000 title claims abstract description 23
- 239000004676 acrylonitrile butadiene styrene Substances 0.000 claims abstract description 59
- 238000000034 method Methods 0.000 claims abstract description 43
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims abstract description 43
- 239000004926 polymethyl methacrylate Substances 0.000 claims abstract description 43
- 239000002245 particle Substances 0.000 claims abstract description 27
- 230000008569 process Effects 0.000 claims description 28
- 238000009210 therapy by ultrasound Methods 0.000 claims description 23
- 238000005273 aeration Methods 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 239000007864 aqueous solution Substances 0.000 claims description 10
- 238000011084 recovery Methods 0.000 abstract description 31
- 238000005516 engineering process Methods 0.000 abstract description 11
- 239000000203 mixture Substances 0.000 abstract description 5
- XECAHXYUAAWDEL-UHFFFAOYSA-N acrylonitrile butadiene styrene Chemical compound C=CC=C.C=CC#N.C=CC1=CC=CC=C1 XECAHXYUAAWDEL-UHFFFAOYSA-N 0.000 description 55
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 55
- 239000004800 polyvinyl chloride Substances 0.000 description 44
- 229920000915 polyvinyl chloride Polymers 0.000 description 44
- 239000010410 layer Substances 0.000 description 30
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 16
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 16
- 229940116411 terpineol Drugs 0.000 description 16
- 238000004140 cleaning Methods 0.000 description 15
- 238000007667 floating Methods 0.000 description 12
- 238000003756 stirring Methods 0.000 description 12
- 239000011575 calcium Substances 0.000 description 8
- 238000001914 filtration Methods 0.000 description 7
- 238000011160 research Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 5
- 230000001276 controlling effect Effects 0.000 description 5
- 238000004064 recycling Methods 0.000 description 4
- 238000002604 ultrasonography Methods 0.000 description 4
- 238000004090 dissolution Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- 238000003760 magnetic stirring Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000080 wetting agent Substances 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000004088 foaming agent Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- CSNNHWWHGAXBCP-UHFFFAOYSA-L magnesium sulphate Substances [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 239000012994 photoredox catalyst Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000000527 sonication Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/02—Separating plastics from other materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/02—Separating plastics from other materials
- B29B2017/0203—Separating plastics from plastics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/02—Separating plastics from other materials
- B29B2017/0213—Specific separating techniques
- B29B2017/0217—Mechanical separating techniques; devices therefor
- B29B2017/0248—Froth flotation, i.e. wherein gas bubbles are attached to suspended particles in an aerated liquid
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
Landscapes
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Mechanical Engineering (AREA)
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
- Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
Abstract
The invention discloses a waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment, which comprises the steps of crushing a mixture formed by combining more than two of PMMA, PVC, PS and ABS into mixed plastic particles, carrying out calcium hydroxide pretreatment on the obtained mixed plastic particles, and respectively carrying out flotation separation I, ultrasonic I, flotation separation II and ultrasonic II flotation separation III on the mixed plastic particles obtained through pretreatment to respectively obtain PMMA, PS, PVC and ABS. The invention provides a method for efficiently and selectively separating various plastics in waste plastics, and the technology has the advantages of easy operation control and low cost, and provides technical support for the separation and recovery of the waste plastics.
Description
Technical Field
The invention relates to a method for separating waste mixed plastics, belonging to the technical field of waste plastic recovery.
Background
Plastic products change our production and lifestyle, and the problems that follow are that the large consumption of plastic and the short service life of plastic cause serious environmental pollution and waste of resources. According to statistics, the annual production of waste plastics in China is about 100 ten thousand tons, and the waste plastics account for about 70 percent of the plastic yield. The production amount of the waste plastics is so large, but the recycling rate of the waste plastics in China is low at present and is almost less than 20 percent of the total amount of the plastics, so that the waste plastics are necessary to be recycled. In the process of recycling waste plastics, different plastics need to be separated, and the separation of the plastics is a bottleneck link restricting the process of recycling the waste plastics at present.
The mixed plastic separation techniques developed include hand sorting, gravity separation, flotation, electrostatic separation, and selective dissolution. The manual sorting process of plastics has high labor intensity, severe working environment and low separation efficiency. Gravity separation and electrostatic separation have great limitations on the separation of mixed plastics with similar physical properties. The flotation has obvious advantages for separating the waste plastics and has huge application prospect. The existing flotation technology capable of separating PMMA, PVC, PS and ABS comprises a boiling water treatment technology, a chemical oxidation technology, an advanced oxidation technology, an ammonia water treatment technology, an alkali treatment technology, a mechanochemical technology, a wetting agent inhibition technology and the like. The main problems of the technologies include the application of more chemical reagents which are not allowed by environmental supervision departments, higher energy consumption, poor test reproducibility, change of the chemical structure of the plastic surface layer and the like. In addition, the low profit of the plastic recycling and the diversity of the waste plastics limit the development of plastic separation technology. Therefore, development of a separation technique with low cost, high adaptability and high separation efficiency is an important problem in the art.
Disclosure of Invention
Aiming at the defects of the prior art in separating the waste mixed plastics, the invention provides a method based on calcium hydroxide (Ca (OH)2) The pre-treated waste mixed plastic full-priority flotation separation method aims at realizing the separation and recovery of mixed plastic with high selectivity and high recovery rate.
A waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment is characterized in that waste mixed plastic is placed in a calcium hydroxide solution and pretreated at the temperature of not lower than 20 ℃, and the pretreated waste mixed plastic is subjected to a priority flotation process to realize the separation of all plastics in the waste mixed plastic;
the waste mixed plastic comprises N of PMMA (polymethyl methacrylate), PVC (polyvinyl chloride), PS (polystyrene) and ABS (acrylonitrile-butadiene-styrene plastic), wherein N is an integer not less than 2.
The present invention has innovatively found that, in the case of a mixed plastic containing two or more of MMA, PVC, PS, and ABS, the difference in each component in the mixed plastic can be amplified by pretreating the mixed plastic with the calcium hydroxide solution under the temperature conditions, and each plastic component in the mixed plastic can be separated with high selectivity and high recovery rate by the preferential flotation method.
It was found that pretreatment in calcium hydroxide solution at the temperature conditions described is critical to achieve selective separation of mixed plastics. The inventor researches and discovers that calcium hydroxide is used as a modifier, and the mixed plastic can be differentially modified by controlling the temperature of the pretreatment process, so that the high-selectivity separation of each component of the mixed plastic can be unexpectedly realized.
Preferably, the particle size of the waste mixed plastic is 0.5-5 mm.
The inventor further finds that the solute concentration of the calcium hydroxide solution in the pretreatment process is further regulated, and the recovery rate and selectivity of the plastic are further improved.
Preferably, the concentration of the solute of the calcium hydroxide solution is 0.01-5 g/L; preferably 0.15-0.2 g/L.
The mass ratio of the calcium hydroxide in the calcium hydroxide solution in the pretreatment process to the mixed plastic is further regulated and controlled, and the recovery rate and the selectivity of the plastic are further improved. Preferably, the calcium hydroxide in the calcium hydroxide solution is 0.0001-0.1 times of the total mass of the mixed plastic.
The inventor further researches and discovers that controlling the pretreatment temperature and time under the pretreatment condition helps to further improve the separation effect of the mixed plastics.
The temperature of pretreatment is 20-60 ℃; more preferably 50 to 60 ℃.
The pretreatment process is carried out under the stirring condition, and the preferable stirring speed is 800-1200 r/min.
Preferably, the pretreatment time is 1-30 min; more preferably 20 to 30 min.
The invention is applied to the field of mixed plastic separation by adopting a preferential flotation method for the first time. The mixed plastics can be gradually floated and separated according to the priority order of PMMA, PS, ABS and PVC through the pretreatment process; thereby achieving the separation of each plastic component with high selectivity and high recovery rate.
In the invention, the preferential flotation process comprises N-1 times of flotation which are carried out in sequence.
In the present invention, if the mixed plastic is two types (N ═ 2) of PMMA, PS, ABS and PVC, the mixed plastic is subjected to the above-described pretreatment, and subjected to primary flotation, a plastic component that floats relatively preferentially is obtained from the upper layer of the flotation, and the lower layer is another plastic component, in the order of the above-described preferential flotation.
When the mixed plastics are three plastics (N is 3) of PMMA, PS, ABS and PVC, the mixed plastics are pretreated, first flotation is carried out, plastic components which float upwards relatively preferentially are obtained from the upper layer of the flotation according to the preferential flotation sequence, and the lower layer is the rest two mixed plastics. The mixed plastic of the lower layer is subjected to a second flotation, wherein the plastic floating preferentially relative to the plastic is located in the upper layer. Thereby realizing the selective separation of the three plastics.
When the mixed plastic is three plastics (N is 4) of PMMA, PS, ABS and PVC, the mixed plastic is pretreated, first flotation is carried out, plastic components (PMMA) which float upwards relatively preferentially are obtained from the upper layer of the flotation according to the preferential flotation sequence, and the remaining three mixed plastics (PS, ABS and PVC) are arranged at the lower layer. And carrying out secondary flotation on the mixed plastic of the lower layer, wherein the plastic floating preferentially relatively is positioned on the upper layer (PS), and the mixed plastic of the lower layer is ABS and PVC. And carrying out third flotation on the ABS and PVC on the lower layer to enable the ABS to float upwards, thereby realizing the selective separation of the four plastics.
Preferably, when N is more than or equal to 3, performing ultrasonic treatment on the mixed plastic at the bottom layer of the previous flotation and then performing flotation; the ultrasound is ultrasonic treatment in aqueous solution.
Research finds that when the mixed plastics are three or more of PMMA, PS, ABS and PVC, the pretreated mixed plastics are subjected to first flotation, so that plastic components floating relatively preferentially float upwards in the mixed plastics, and the mixed plastics sinking in the first flotation are subjected to ultrasonic treatment before the next flotation, so that the difference of the surface properties of the sinking mixed plastics in the first flotation is amplified, and the subsequent flotation and recovery are facilitated.
For example, when the mixed plastic is three plastics (N ═ 3) of PMMA, PS, ABS and PVC, the mixed plastic is subjected to the pretreatment, and subjected to the first flotation, plastic components that float relatively preferentially are obtained from the upper layer of the flotation, and the remaining two mixed plastics are obtained from the lower layer in the order of the preferential flotation. The mixed plastic of the lower layer is subjected to ultrasound (the mixed plastic of the lower layer is differentiated in properties), and then subjected to secondary flotation, wherein the plastic floating preferentially to the upper layer is positioned on the upper layer. Thereby realizing the selective separation of the three plastics.
For example, the mixed plastics are three plastics (N ═ 4) of PMMA, PS, ABS and PVC, the mixed plastics are subjected to the pretreatment, and after the first flotation, PMMA is obtained from the upper layer of the flotation, and the remaining three mixed plastics (PS, ABS and PVC) are obtained from the lower layer in the order of the preferential flotation. And (3) performing ultrasonic treatment on the mixed plastic at the lower layer, and then performing secondary flotation to enable PS to float upwards, wherein the mixed plastic at the lower layer is ABS and PVC. And carrying out second ultrasonic treatment on the lower layer mixed plastic subjected to the second flotation, and then carrying out third flotation to enable the ABS to float upwards, wherein the bottom layer is PVC. Thereby realizing the selective separation of the four plastics.
Research shows that the first flotation of the pretreated mixed plastics can achieve a flotation recovery rate of 95% or more. In order to further improve the selectivity and the recovery rate of the mixed plastics in the lower layer of the first flotation, the selection can be realized by controlling the process conditions of the ultrasound.
The medium of the sonication process may be an aqueous solution.
Preferably, the method comprises the following steps: the ultrasonic power is 100-600W.
Ultrasonic time: 10min and above; preferably 10-30 min.
The inventor researches and discovers that the selectivity and the recovery rate of the lower mixed plastic after the first flotation can be unexpectedly ensured by controlling the ultrasonic process.
And carrying out solid-liquid separation on the mixed plastic solution system after the ultrasonic treatment, wherein the solid obtained by the separation is the mixed plastic after the ultrasonic treatment, and then carrying out subsequent flotation on the mixed plastic after the ultrasonic treatment.
In the invention, the flotation operation method can refer to the existing method.
Preferably, the medium for each flotation is water, and terpineol is used as a foaming agent in the flotation process.
Preferably, the aeration amount is 100-800 mL/min.
Preferably, the time for each flotation does not exceed 20 min.
The invention provides a waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment, which specifically comprises the following steps:
the method comprises the following steps: firstly, crushing waste mixed plastics into mixed plastic particles with the granularity of about 0.5-5 mm, and then adding the obtained particles into Ca (OH)2The suspension is pretreated at the temperature of more than 20 ℃, and finally, the first flotation separation is carried out.
Step two: firstly, carrying out ultrasonic treatment 1 on a first flotation sinking product at normal temperature for a period of time, and carrying out second flotation separation after filtering and cleaning.
Step three: firstly, carrying out ultrasonic treatment 2 on the secondary flotation sinking product at normal temperature for a period of time, and carrying out tertiary flotation separation after filtering and cleaning.
The technical scheme is based on the weak interaction force difference of calcium hydroxide molecules and plastic surface molecules to carry out selective adhesion, so that the plastic is hydrophilic and sinks in the flotation process. It was preliminarily determined that the weak interaction may be cation-pi interaction and hydrogen bonding.
Advantageous effects
The invention innovatively realizes the selective separation of the mixed plastics with high selectivity and high recovery rate by the pretreatment of the calcium hydroxide solution and the preferential flotation method.
According to the method, the recovery rate of the plastic subjected to the first flotation can be ensured to be up to 95% or more through the pretreatment, and researches also find that the recovery rate and the selectivity of the mixed plastic at the lower layer of the flotation can be ensured to be up to 90% through further performing ultrasonic treatment on the mixed plastic at the lower layer of the first flotation.
The technical scheme of the invention does not need the technical barrier of adding a wetting agent as generally known in the prior art, and the high-selectivity separation between plastics can be realized by the simple pretreatment and flotation method.
In addition, the inventor also unexpectedly finds that the method can ensure the stability of the process effect of each batch of treatment compared with the prior art.
Drawings
FIG. 1 is a process flow diagram of example 1.
Detailed Description
The invention is further illustrated by the following examples, which are not to be construed in any way as imposing limitations upon the scope thereof. On the contrary, it is to be clearly understood that resort may be had to various other embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to those skilled in the art without departing from the spirit of the present invention and/or the scope of the appended claims.
Example 1
Crushing a mixed plastic of PMMA, PS and ABS by using a plastic crusher, adding a proper amount of water into the crusher to ensure that the temperature of the plastic is lower than 40 ℃ in the mechanical crushing process, taking 3g of plastic (the mass ratio of PMMA, PC and ABS is 1:1:1) with the particle size of 2-4 mm, adding the plastic into a beaker filled with 0.15g of calcium hydroxide and 100mL of water, and carrying out magnetic stirring for 20min at the stirring speed of 800r/min at the set temperature of 50 ℃. Then, carrying out first flotation under the following conditions: and carrying out flotation for 3min by using 200mg/L terpineol, wherein the aeration rate is 200 mL/min. PMMA is obtained by separation, the purity reaches 97 percent, and the recovery rate reaches 97 percent. Ultrasonic treatment (400W for 10min) is carried out on the separated and sunk waste plastic (PS and ABS mixed plastic) at normal temperature. Carrying out secondary flotation after ultrasonic treatment, wherein the flotation conditions are as follows: and carrying out flotation for 3min by using 200mg/L terpineol, wherein the aeration rate is 200 mL/min. The floating PS is obtained by separation, the purity of the PS reaches about 96 percent, the recovery rate of the PS reaches about 96 percent, the purity of the sinking ABS reaches about 96 percent, and the recovery rate of the ABS reaches 96 percent.
Example 2
Crushing a mixed plastic of PMMA, ABS and PVC by using a plastic crusher, adding a proper amount of water into the crusher in the mechanical crushing process to ensure that the temperature of the plastic is lower than 40 ℃, taking 3g of plastic (the mass ratio of PMMA, ABS and PVC is 1:1:1) with the particle size of 2-4 mm, adding the plastic into a beaker filled with 0.01g of calcium hydroxide and 100mL of water, and carrying out magnetic stirring for 20min at the stirring speed of 800r/min at the set temperature of 50 ℃. Then, carrying out first flotation under the following conditions: and carrying out flotation for 3min by using 200mg/L terpineol, wherein the aeration rate is 200 mL/min. PMMA is obtained by separation, the purity reaches 97.31%, and the recovery rate reaches 96.67%. Separating residual waste plastics (ABS and PVC mixture) and carrying out ultrasonic treatment (100W, 20min) at normal temperature, and carrying out secondary flotation after ultrasonic treatment, wherein the flotation conditions are as follows: and carrying out flotation for 3min by using 200mg/L terpineol, wherein the aeration rate is 200 mL/min. The purity of the floated ABS obtained by separation reaches 95.54 percent, the recovery rate reaches 95.47 percent, and the purity and the recovery rate of the settled PVC respectively reach 96.87 percent and 94.77 percent.
Example 3
Crushing the mixed plastic of PMMA, PS, ABS and PVC by using a plastic crusher, adding a proper amount of water into the crusher in the mechanical crushing process to ensure that the temperature of the plastic is lower than 40 ℃, taking 4g of plastic (the mass ratio of PMMA, PS, ABS and PVC is 1:1:1) with the particle size of 2-4 mm, adding the plastic into a beaker filled with 0.2g of calcium hydroxide and 100mL of water, and carrying out magnetic stirring for 20min at the stirring speed of 800r/min at the set temperature of 50 ℃. Then, carrying out first flotation under the following conditions: and carrying out flotation for 3min by using 200mg/L terpineol, wherein the aeration rate is 200 mL/min. PMMA is obtained by separation, the purity reaches 96.78 percent, and the recovery rate reaches 95.35 percent. The remaining waste plastics (mixture of PS, ABS and PVS) were separated and sonicated at ambient temperature (600W, 15 min). Carrying out secondary flotation after ultrasonic treatment, wherein the flotation conditions are as follows: and carrying out flotation for 3min by using 200mg/L terpineol, wherein the aeration rate is 200 mL/min. Separating to obtain floating product PS with purity up to 95.48% and recovery rate up to 95.91% and mixed sinking product (ABS and PVC). Carrying out secondary ultrasonic treatment (400W for 20min) on the residual waste plastics at normal temperature, and carrying out tertiary flotation on the treated plastic mixture, wherein the flotation conditions are as follows: and carrying out flotation for 3min by using 200mg/L terpineol, wherein the aeration rate is 200 mL/min. The purity of the floated ABS obtained by separation reaches 91.85%, the recovery rate reaches 97.31%, the purity of the settled PVC reaches 98.9%, and the recovery rate reaches 90.37.
Example 4
Cleaning and crushing mixed plastic containing PVC and PMMA, taking 2g of plastic particles with the particle diameter of 2-4 mm respectively, and using Ca (OH) with the concentration of 0.01g/L at the temperature of 60 DEG C2Treating the aqueous solution for 30min, wherein the optimal flotation conditions comprise 200mg/L of terpineol, 700-800 mL/min of aeration amount and 3min of flotation time. The floating product PMMA obtained by flotation has the purity of 95.10 percent, the recovery rate of 95.21 percent, the sinking product PVC has the purity of 96.38 percent and the recovery rate of 94.38 percent.
Example 5
Cleaning and crushing mixed plastic containing PVC and PMMA, taking 2g of plastic particles with the particle diameter of 2-4 mm respectively, and using Ca (OH) with the concentration of 5g/L at the temperature of 20 DEG C2Treating the aqueous solution for 4min, wherein the optimal flotation conditions comprise 200mg/L of terpineol, 700-800 mL/min of aeration amount and 3min of flotation time. The floating product PMMA obtained by flotation has the purity of 98.82 percent, the recovery rate of 92.31 percent, the sinking product PVC has the purity of 93.56 percent and the recovery rate of 97.75 percent.
Comparative example 1
The main difference compared with example 1 is that CaCl is used2The pretreatment agent is specifically operated as follows:
cleaning and crushing mixed plastic containing PVC, PS, ABS and PMMA, taking 4g of plastic particles (the mass ratio of PMMA: PVC: ABS: PS is 1:1:1) with the particle size of 2-4 mm, and using CaCl with the concentration of 2g/L at the temperature of 40 DEG C2And (3) treating the aqueous solution for 15min, wherein the stirring speed in the treatment process is 800r/min, filtering, cleaning and then performing flotation separation, wherein the flotation conditions comprise 200mg/L of terpineol, 700-800 mL/min of aeration and 3min of flotation time. PVC, PS, ABS and PMMA float upwards, and flotation separation of mixed plastics cannot be realized. CaCl2Complete dissolution in water does not achieve surface adhesion.
Comparative example 2
The main difference compared with example 1 is that MgSO is used4The pretreatment agent is specifically operated as follows:
cleaning and crushing mixed plastic containing PVC, PS, ABS and PMMA, taking 4g of plastic particles with the particle diameter of 3-5 mm (the mass ratio of PMMA: PVC: ABS: PS is 1:1:1), and using the plastic particles with the concentration of 2g/L at the temperature of 40 DEG CMgSO4And (3) treating the aqueous solution for 15min, wherein the stirring speed in the treatment process is 900r/min, filtering, cleaning and then performing flotation separation, wherein the flotation conditions comprise 200mg/L of terpineol, 700-800 mL/min of aeration and 3min of flotation time. PVC, PS, ABS and PMMA float upwards, flotation separation of mixed plastics cannot be realized, MgSO4Complete dissolution in water does not achieve surface adhesion.
Comparative example 3
Compared with the example 1, the main difference is that the pretreatment temperature is 10 ℃, and the specific operation is as follows:
cleaning and crushing mixed plastic containing PVC, PS, ABS and PMMA, taking 4g of plastic particles with the particle diameter of 2-4 mm (the mass ratio of PMMA: PVC: ABS: PS is 1:1:1), and using CaSO with the concentration of 2g/L at the temperature of 10 DEG C4And (3) treating the aqueous solution for 15min, wherein the stirring speed in the treatment process is 1000r/min, filtering, cleaning and then performing flotation separation, wherein the flotation conditions comprise 200mg/L of terpineol, 700-800 mL/min of aeration and 3min of flotation time. PVC, PS, ABS and PMMA float upwards, and flotation separation of mixed plastics cannot be realized. Temperature too low Ca (OH)2Cannot adhere to the plastic surface.
Comparative example 4
The main difference compared to example 1 is that the concentration of pretreated calcium hydroxide is below the lower limit of the present invention, and the specific operation is as follows:
cleaning and crushing mixed plastic containing PVC, PS, ABS and PMMA, taking 4g of plastic particles with the particle diameter of 2-4 mm (the mass ratio of PMMA: PVC: ABS: PS is 1:1:1), and using 0.005g/L Ca (OH) at the temperature of 40 DEG C2And (3) treating the aqueous solution for 15min, wherein the stirring speed in the treatment process is 1000r/min, filtering, cleaning and then performing flotation separation, wherein the flotation conditions comprise 200mg/L of terpineol, 700-800 mL/min of aeration and 3min of flotation time. PVC, PS, ABS and PMMA float upwards, and flotation separation of mixed plastics cannot be realized. Too low a concentration without sufficient Ca (OH)2Can not be adhered to the surface of the plastic, and the plastic floats upwards completely.
Example 6
Compared with the example 2, the main difference is that after the first flotation, the ultrasonic treatment is replaced by stirring, and the operation is as follows:
cleaning and crushing mixed plastic containing PVC, PS and ABS, taking 4g of plastic particles with the particle diameter of 2-4 mm (the mass ratio of PVC to ABS to PS is 1:1:1), and using Ca (OH) with the concentration of 1g/L at the temperature of 40 DEG C2And (3) treating the aqueous solution for 15min, wherein the stirring speed in the treatment process is 1000r/min, filtering, cleaning and then performing flotation separation, wherein the flotation conditions comprise 200mg/L of terpineol, 700-800 mL/min of aeration and 3min of flotation time. The floating purity and yield of PMMA are respectively 97.74% and 99.21%, the sinking product is a mixture of PS and ABS, after stirring for 20min at 500r/min, the floating rates of ABS and PS are respectively 40.12% and 60.41%, and more accurate separation cannot be realized.
Example 7
After the first flotation, ultrasound with non-preferred power is used, and the operation is as follows:
cleaning and crushing the PS and ABS mixed plastic, and taking 4g of plastic particles with the particle size of 3-5 mm, wherein the PS and the ABS respectively account for two grams and use 1g/L Ca (OH)2The solution was treated at 50 ℃ for 35min and subjected to flotation. The flotation conditions comprise 200mg/L of terpineol, 700-800 mL/min of aeration amount and 3min of flotation time. The floating rates of PS and ABS are respectively 7.26% and 9.31%, the ABS and PS are pretreated under the same condition and then are subjected to ultrasonic treatment for 60min under the condition of 50W power, the floating rates of PS and ABS are respectively 50.30% and 46.77%, and the flotation separation of ABS and PS cannot be realized.
According to the above examples and comparative examples, the calcium hydroxide pretreatment according to the present invention and the preferred flotation method can sequentially float and separate the mixed plastics according to the priority of PMMA, PS, ABS and PVC. Research also finds that the selectivity and the recovery rate of the bottom layer mixed plastic can be ensured on the premise of ensuring the flotation rate and the recovery rate of the plastic subjected to the first flotation by further controlling the calcium hydroxide pretreatment parameters and carrying out ultrasonic treatment on the bottom layer mixed plastic subjected to the first flotation.
Claims (6)
1. A waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment is characterized by comprising the following steps: the waste mixed plastic is put into a calcium hydroxide solution and pretreated at the temperature of not lower than 20 ℃, and the pretreated waste mixed plastic is subjected to a preferential flotation process to realize the separation of all plastics in the waste mixed plastic; the solute concentration of the calcium hydroxide solution is 0.01-5 g/L;
the waste mixed plastic comprises N of PMMA, PVC, PS and ABS, and N is an integer not less than 2;
the preferential flotation process comprises N-1 times of flotation which are carried out in sequence;
when N is more than or equal to 3, performing ultrasonic flotation on the mixed plastic at the bottom layer of the previous flotation and then performing flotation; the ultrasonic treatment is ultrasonic treatment in aqueous solution; the ultrasonic power is 100-600W; the ultrasonic treatment time is 10min or more;
and in the preferential flotation process, the plastics in the mixed plastics are sequentially floated and separated according to the priority of PMMA, PS, ABS and PVC.
2. The full-priority flotation separation method for waste mixed plastics based on calcium hydroxide pretreatment as claimed in claim 1, characterized in that: the calcium hydroxide in the calcium hydroxide solution is 0.0001-0.1 time of the total mass of the mixed plastic.
3. The full-priority flotation separation method for waste mixed plastics based on calcium hydroxide pretreatment as claimed in claim 2, characterized in that: the concentration of the solute of the calcium hydroxide solution is 0.15-0.2 g/L.
4. The full-priority flotation separation method for waste mixed plastics based on calcium hydroxide pretreatment as claimed in claim 1, characterized in that: the pretreatment time is 1-30 min.
5. The waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment as claimed in any one of claims 1 to 4, wherein the method comprises the following steps: the medium of each flotation is water, the aeration quantity is 100-800 mL/min, and the time of each flotation is not more than 20 min.
6. The full-priority flotation separation method for waste mixed plastics based on calcium hydroxide pretreatment as claimed in claim 1, characterized in that: the particle size of the waste mixed plastic is 0.5-5 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910013223.4A CN111409212B (en) | 2019-01-07 | 2019-01-07 | Waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910013223.4A CN111409212B (en) | 2019-01-07 | 2019-01-07 | Waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111409212A CN111409212A (en) | 2020-07-14 |
| CN111409212B true CN111409212B (en) | 2021-07-09 |
Family
ID=71487395
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910013223.4A Expired - Fee Related CN111409212B (en) | 2019-01-07 | 2019-01-07 | Waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111409212B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114953249A (en) * | 2022-05-17 | 2022-08-30 | 格林美(武汉)城市矿山产业集团有限公司 | PVC plastic recovery method for scrap car crushing residues, modified PVC plastic and preparation method |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1451571A (en) * | 1973-08-06 | 1976-10-06 | Mitsui Mining & Smelting Co | Method for separating polyvinyl chloride from a mixture of plastics by flotation |
| CN101274993A (en) * | 2008-05-16 | 2008-10-01 | 浙江工业大学 | PET/PVC separation method |
| CN105348556A (en) * | 2015-11-11 | 2016-02-24 | 广东金发科技有限公司 | Suspension used for flotation separation of waste plastic, preparing method thereof and applications of the suspension |
| CN105399983A (en) * | 2015-12-09 | 2016-03-16 | 中南大学 | A separating method of mixed plastics |
| CN206085400U (en) * | 2016-06-17 | 2017-04-12 | 江西格林美资源循环有限公司 | Regeneration treatment device of electron wastes material plastics |
| CN106881782A (en) * | 2017-02-21 | 2017-06-23 | 长安大学 | A kind of method of FLOTATION SEPARATION high density polyethylene (HDPE), polypropylene and polyethylene terephthalate in mixed plastic from multicomponent |
-
2019
- 2019-01-07 CN CN201910013223.4A patent/CN111409212B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1451571A (en) * | 1973-08-06 | 1976-10-06 | Mitsui Mining & Smelting Co | Method for separating polyvinyl chloride from a mixture of plastics by flotation |
| CN101274993A (en) * | 2008-05-16 | 2008-10-01 | 浙江工业大学 | PET/PVC separation method |
| CN105348556A (en) * | 2015-11-11 | 2016-02-24 | 广东金发科技有限公司 | Suspension used for flotation separation of waste plastic, preparing method thereof and applications of the suspension |
| CN105399983A (en) * | 2015-12-09 | 2016-03-16 | 中南大学 | A separating method of mixed plastics |
| CN206085400U (en) * | 2016-06-17 | 2017-04-12 | 江西格林美资源循环有限公司 | Regeneration treatment device of electron wastes material plastics |
| CN106881782A (en) * | 2017-02-21 | 2017-06-23 | 长安大学 | A kind of method of FLOTATION SEPARATION high density polyethylene (HDPE), polypropylene and polyethylene terephthalate in mixed plastic from multicomponent |
Non-Patent Citations (3)
| Title |
|---|
| Combination of three-stage sink-float method and selective flotation technique for separation of mixed post-consumer plastic waste;Pongstabodee, Sangobtip et al.;《WASTE MANAGEMENT》;20070509;第28卷(第3期);第475-483页 * |
| Flotability and flotation separation of polymer materials modulated by wetting agents;Wang Hui et al.;《WASTE MANAGEMENT》;20131216;第34卷(第2期);第309-315页 * |
| Role of calcium ions in the mechanism of action of a lignosulphonate used to modify the wettability of plastics for their separation by flotation;C. Le Guern et al.;《Minerals Engineering》;20000131;第13卷(第1期);第53-63页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111409212A (en) | 2020-07-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Shent et al. | A review of plastics waste recycling and the flotation of plastics | |
| Wang et al. | Flotation separation of waste plastics for recycling—A review | |
| CN104511369B (en) | Method for waste mixed plastic separation | |
| Wang et al. | Flotation separation of polyvinyl chloride and polyethylene terephthalate plastics combined with surface modification for recycling | |
| Hashim et al. | Application of colloidal gas aphrons for pollution remediation | |
| CN111409212B (en) | Waste mixed plastic full-priority flotation separation method based on calcium hydroxide pretreatment | |
| US20220001395A1 (en) | Flotation process for treating coal slime by using salt-containing waste water | |
| CN109731697A (en) | A kind of width grade floatation system and technique | |
| CN105399983B (en) | A kind of separation method of mixed plastic | |
| CN107638960B (en) | The method of separating boron | |
| US5494811A (en) | Biparticle fluidized bed reactor | |
| US4584271A (en) | Bacterial regeneration apparatus and process | |
| CN111298954A (en) | Process for heavy-medium separation of oil shale from two pressurized products | |
| RU2002117418A (en) | Improved flotation method for sulfide minerals | |
| US6309547B1 (en) | Anaerobic treatment process with removal of nonbiodegradable organic material | |
| CN110421744B (en) | Method for flotation separation of polyvinyl chloride from waste mixed plastic based on calcium carbonate pretreatment | |
| CN111409213B (en) | Waste mixed plastic full-priority flotation separation method based on calcium sulfate pretreatment | |
| CN213569929U (en) | Coal mine water resource comprehensive utilization system | |
| CN101274993B (en) | PET/PVC separation method | |
| CN101962236B (en) | Process for recovering streptomycin sulphate from waste water by coupling foam separation and ion exchange | |
| CN108034070B (en) | Waste plastic separation method | |
| CN109046757B (en) | Mineral separation method for gravity separation reverse flotation decalcification of high-calcium fine-grain mica type vanadium ore | |
| CN108247897B (en) | A kind of separation method of mixed plastic | |
| CN113186231B (en) | Method for producing volatile fatty acid by co-fermentation of waste plastic and sludge | |
| CN108748793A (en) | A kind of separation method of mixed plastic |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20210709 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |