CN114517261A - Method and device for selectively extracting and recovering chromium element in electroplating sludge - Google Patents
Method and device for selectively extracting and recovering chromium element in electroplating sludge Download PDFInfo
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- CN114517261A CN114517261A CN202111477425.8A CN202111477425A CN114517261A CN 114517261 A CN114517261 A CN 114517261A CN 202111477425 A CN202111477425 A CN 202111477425A CN 114517261 A CN114517261 A CN 114517261A
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- 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
- C22B7/006—Wet processes
- C22B7/007—Wet processes by acid leaching
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- 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
- C22B1/00—Preliminary treatment of ores or scrap
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- 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
- C22B34/00—Obtaining refractory metals
- C22B34/30—Obtaining chromium, molybdenum or tungsten
- C22B34/32—Obtaining chromium
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- 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
- C22B7/006—Wet processes
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Abstract
The invention discloses a method and a device for selectively extracting and recovering chromium element in electroplating sludge, wherein the method comprises the following steps: s1, sequentially dehydrating, drying, roasting and crushing the electroplating sludge to obtain sludge particles to be leached; s2, mixing sludge particles to be leached with a sulfuric acid solution, heating, performing ultrasonic treatment, and then filtering; s3, adding an ethanol solution into the leachate treated in the step S2, uniformly mixing, and then carrying out gasification treatment to obtain gas-phase chromium elements; finally, introducing the gas-phase chromium element into a ferrous sulfate heptahydrate solution for reaction to form trivalent chromium precipitate, and separating the trivalent chromium precipitate; the method has reasonable design and high recovery rate of chromium element in the electroplating sludge, realizes resource utilization of the electroplating sludge, and has obvious economic benefit and environmental benefit.
Description
Technical Field
The invention relates to the technical field of electroplating sludge treatment, in particular to a method and a device for selectively extracting and recovering chromium elements in electroplating sludge.
Background
Chromium in the electroplating sludge is easily oxidized into soluble composite anions and then transferred into surface water or underground water by leaching. When the chromium in the soil is excessive, the nitrification of organic substances can be inhibited, and the chromium is accumulated in the plant body, natural water generally only contains trace chromium and is conveyed into the sea through a river to sink to the sea bottom, and when the contents of underground water are accumulated to a certain degree, the crops stop growing and are about to die.
Then, in the prior art, when the metal elements in the electroplating sludge are separated and recovered, the electroplating sludge contains various heavy metal elements such as copper, zinc, nickel, chromium and the like due to high water content and complex components; metals are mostly present in states of hydroxides, oxides, carbonates and the like, and the fluctuation range of the metal content is large; therefore, the selective extraction and recovery of chromium element are difficult to realize.
Disclosure of Invention
Aiming at the technical problems, the invention provides a method and a device for selectively extracting and recovering chromium in electroplating sludge.
The technical scheme of the invention is as follows: a method for selectively extracting and recovering chromium element in electroplating sludge comprises the following steps:
s1, pretreatment of electroplating sludge:
s1-1, introducing the electroplating sludge into a dehydration device, carrying out pressure-maintaining dehydration treatment for 30-55 min under the pressure of 1.8-2.5 MPa, and drying until the water content is less than 20% to obtain dried sludge;
s1-2, placing the dried sludge obtained in the step S1-1 into a roasting furnace, roasting at the temperature of 300-780 ℃ for 20-45 min in the air atmosphere, naturally cooling, crushing, and sieving with a 20-50-mesh sieve to obtain sludge particles to be leached;
s2, acid leaching:
s2-1, preparing a sulfuric acid solution with the mass concentration of 5-11%, and then mixing the sulfuric acid solution with the sludge particles to be leached obtained in the step S1-2 according to the volume ratio of 5-8: 1 to obtain a mixture A;
s2-2, heating the mixture A obtained in the step S2-1 to 30-90 ℃, and then carrying out ultrasonic treatment for 20-60 min at the frequency of 22-35 kHz and the power of 630-880W to obtain a mixture B; finally, filtering the mixture B to obtain a filtrate;
s2-3, standing the filtrate obtained in the step S2-2 for 45-85 min, and extracting supernatant to obtain leachate;
s3, enriching chromium elements:
s3-1, adding an ethanol solution with the concentration of 5-13% into the leachate obtained in the step S2-3, stirring and mixing uniformly, then introducing into a gasification box, and carrying out gasification treatment at the temperature of 250-480 ℃ to obtain a gas-phase chromium element;
s3-2, introducing the gas-phase chromium element obtained in the step S3-1 into a ferrous sulfate heptahydrate solution with the mass concentration of 15-23% to react for 30-55 min, forming trivalent chromium precipitate, and separating the trivalent chromium precipitate.
Further, after the step S1-2 is finished, placing sludge particles to be leached into a drier, and drying at 880-1050 ℃ for 25-45 min; by carrying out drying treatment on sludge particles to be leached, organic matters and combustible impurities in the sludge particles to be leached can be effectively removed, the separation difficulty of chromium elements in electroplating sludge is reduced, and the extraction efficiency of the chromium elements is improved.
Further, after the step S3-2 is completed, firstly, carrying out adsorption treatment on a ferrous sulfate heptahydrate solution by using ion exchange resin, then desorbing the ion exchange resin by using a sodium carbonate aqueous solution with the mass concentration of 12-18%, and separating precipitates in a desorption solution; the suspended chromium element in the ferrous sulfate heptahydrate solution can be effectively extracted by carrying out ion exchange resin adsorption treatment on the ferrous sulfate heptahydrate solution.
Further, after the step S2-3 is finished, introducing the leachate into a high-pressure reaction kettle, controlling the temperature of the high-pressure reaction kettle to be 280-350 ℃ and the pressure to be 3-6 MPa, continuously reacting for 10-25 min, and discharging the material from the high-pressure reaction kettle to obtain hydrothermal leachate; by carrying out hydrothermal treatment on the leachate, the viscous organic matters in the leachate can be decomposed, the colloid structure in the leachate can be destroyed, and the enrichment efficiency of the chromium element is improved.
Further, after the step S3-2 is finished, drying the trivalent chromium precipitate at the temperature of 90-120 ℃ to constant weight, and then ball-milling the trivalent chromium precipitate into granules with the particle size of less than 2 mm; the trivalent chromium precipitate is dried and ball-milled, so that the collection and utilization of chromium materials are facilitated.
Further, after the step S2-1 is finished, adding 5-11% by volume of hydrogen peroxide solution with the volume concentration of 4-9% into the mixture A, and reacting for 45-60 min at the temperature of 125-185 ℃; by adding the hydrogen peroxide solution into the mixture A, the conversion efficiency of hexavalent chromium in the mixture A can be improved, new metal ions cannot be introduced, and the extraction efficiency of chromium elements in electroplating sludge is improved.
The invention also provides a selective extraction and recovery device for chromium elements in electroplating sludge, which comprises dehydration equipment for deeply dehydrating the electroplating sludge, a roasting furnace for roasting the dried sludge and a gasification box for gasifying a mixed solution of leachate and an ethanol solution, wherein the dehydration equipment comprises an outer shell, a lifting component, an extrusion dehydration component and a controller; the lower end of the outer shell is provided with a water collecting tank, the water collecting tank is communicated with the inside of the outer shell, and the side wall of the water collecting tank is provided with a drain pipe;
the lifting assembly comprises a lifting sleeve and two lifting motors, the lifting sleeve is movably sleeved inside the outer shell, the outer part of the lifting sleeve is rotatably clamped with a first connecting sleeve at the lower position, the first connecting sleeve is fixedly connected with the inner wall of the outer shell, the two lifting motors are arranged at two sides of the inner part of the outer shell symmetrically through mounting rings and are positioned at the upper end of the first connecting sleeve, lifting lead screws are arranged on output shafts of the lifting motors, and the two lifting lead screws respectively penetrate through the mounting rings and are respectively in threaded connection with the first connecting sleeve;
the squeezing and dewatering component comprises a dewatering cylinder, a squeezing motor, a squeezing plate and a driving motor, the dewatering cylinder is sleeved inside a lifting sleeve, the upper end of the dewatering cylinder is opened, the lower end of the dewatering cylinder is clamped with a movable plate, a plurality of water outlet holes are arranged on the side wall in a penetrating manner, two second connecting sleeves are rotatably clamped on the side wall of the dewatering cylinder and are fixedly connected with the inner wall of the lifting sleeve respectively, the squeezing plate is clamped at the opening at the upper end of the dewatering cylinder in a sliding manner, the squeezing motor is arranged at the top of an outer shell, a squeezing lead screw is arranged on an output shaft of the squeezing motor, the squeezing lead screw penetrates through the squeezing plate and is then rotatably clamped with the bottom in the dewatering cylinder, and the squeezing lead screw is in threaded connection with the squeezing plate; the movable plate is connected with the top of the water collecting tank through a shaft rod, a connecting gear is sleeved on the shaft rod, a driving motor is arranged at the top of the water collecting tank, and a driving gear meshed with the connecting gear is arranged on an output shaft of the driving motor;
the controller is respectively and electrically connected with the lifting motor, the extrusion motor and the driving motor.
Furthermore, a vibrating plate is connected to the extrusion plate in a sliding and clamping mode, a curved surface vibrating sleeve is arranged on the upper end face of the vibrating plate, an installation plate is sleeved on the extrusion screw rod, an extrusion roller is connected to the lower end of the installation plate in a rotating and clamping mode, and the extrusion roller is abutted to the upper end face of the curved surface vibrating sleeve; vibration board and stripper plate junction are provided with the slide bar, and the cover is equipped with reset spring on the slide bar, and reset spring upper end and vibration board butt, lower extreme and stripper plate butt, extrusion lead screw rotate the in-process, drive mounting panel and extrusion roller rotate to make vibration board reciprocating motion from top to bottom under extrusion roller's effect, realize electroplating sludge's vibration extrusion dehydration, be favorable to improving electroplating sludge's dehydration efficiency.
Furthermore, the guide rod is arranged on the mounting ring and is in sliding clamping connection with the outer wall of the lifting sleeve, and the guide rod is arranged, so that the stability of the lifting sleeve during moving is improved, and the running stability of the whole dewatering device is improved.
Furtherly, the header tank upper end is provided with the lag, and the terminal surface rotates the joint under protective cover upper end and the fly leaf, and driving motor is located inside the lag, through setting up the lag, can avoid mud to exert an influence to connecting gear and drive gear's meshing effect.
The working principle of the dehydration equipment is as follows:
s1, respectively connecting the lifting motor, the extrusion motor and the driving motor with an external power supply, and controlling the extrusion motor to rotate reversely through the controller so that the extrusion plate moves upwards along the dewatering cylinder;
s2, placing the electroplating sludge into a dewatering cylinder, controlling a squeezing motor to rotate in the forward direction through a controller, and enabling a squeezing plate to move downwards along the dewatering cylinder under the action of a squeezing screw rod to conduct squeezing and dewatering treatment on the electroplating sludge; meanwhile, in the rotating process of the extrusion lead screw, the mounting plate and the extrusion roller are driven to rotate, so that the vibration plate reciprocates up and down under the combined action of the extrusion roller and the surface vibration sleeve, and the vibration, extrusion and dehydration of the electroplating sludge are realized; sewage separated from the electroplating sludge enters the water collecting tank through the water outlet hole and passes through the water collecting tank of the drain pipe;
s3, after extrusion dehydration of the electroplating sludge is completed, the controller controls the driving motor to drive, and the driving gear is meshed with the connecting gear, so that the movable plate drives the dehydration cylinder to rotate, and centrifugal dehydration of the electroplating sludge is realized;
s4, after centrifugal dehydration of the electroplating sludge is completed, the controller controls the extrusion motor to rotate reversely, so that the extrusion plate moves upwards along the dewatering cylinder, the controller controls the lifting motor to start, the lifting sleeve moves upwards along the guide rod under the action of the lifting screw rod, the dewatering cylinder moves upwards simultaneously under the driving action of the lifting sleeve and is separated from the movable plate, and finally the dehydrated electroplating sludge is removed.
Compared with the prior art, the invention has the beneficial effects that: the method disclosed by the invention is reasonable in design, can realize selective recovery of chromium in the electroplating sludge, can obviously improve the recovery efficiency of the chromium, and is beneficial to promoting the conversion of the chromium into a chromium metal product, so that the resource utilization of the electroplating sludge is realized, and the method has obvious economic benefits and environmental benefits; according to the chemical characteristics of the chromium element, a sulfuric acid solution is used as a leaching solution of the chromium element; meanwhile, in the leaching process of the chromium element, the influence of colloid in the solution on the leaching of the chromium element can be effectively avoided by utilizing an ultrasonic means, and the leaching efficiency of the chromium element is further improved; before leaching out the chromium element in the electroplating sludge, roasting the electroplating sludge to prevent the electroplating sludge from hardening after dehydration and drying, so that the chromium element in the electroplating sludge is promoted to contact with the outside air to be oxidized; the dewatering equipment can realize the extrusion, vibration and centrifugal dewatering treatment of the electroplating sludge, effectively improve the dewatering efficiency of the electroplating sludge, avoid the interference of organic matters in the electroplating sludge on the leaching of chromium elements, simultaneously destroy the complexing action of organic matters such as protein and the like on the chromium, and improve the recovery efficiency of the chromium elements in the electroplating sludge.
Drawings
FIG. 1 is a longitudinal section of the dewatering apparatus of the present invention;
FIG. 2 is a left side view of the dehydration apparatus of the present invention;
FIG. 3 is a schematic view showing the internal structure of the dehydration apparatus of the present invention;
figure 4 is a schematic view of the construction of the dewatering cylinder of the present invention;
figure 5 is a schematic view of the connection of the movable plate of the present invention with the dewatering cylinder;
FIG. 6 is an enlarged schematic view at A of FIG. 1 of the present invention;
the device comprises a shell 1, a water collecting tank 10, a water discharging pipe 11, a protective cover 12, a lifting component 2, a lifting sleeve 20, a first connecting sleeve 200, a lifting motor 21, a mounting ring 210, a guide rod 2100, a lifting screw 211, a squeezing dewatering component 3, a dewatering cylinder 30, a water outlet 300, a second connecting sleeve 301, a squeezing motor 31, a squeezing screw 310, a mounting plate 311, a squeezing roller 312, a squeezing plate 32, a vibrating plate 320, a sliding rod 3200, a return spring 3201, a curved surface vibrating sleeve 321, a movable plate 33, a shaft rod 330, a connecting gear 331, a driving motor 34 and a driving gear 340.
Detailed Description
Example 1
A method for selectively extracting and recovering chromium element in electroplating sludge comprises the following steps:
s1, pretreatment of electroplating sludge:
s1-1, introducing the electroplating sludge into a dehydration device, performing pressure maintaining dehydration treatment for 30min under the pressure of 1.8MPa, and drying until the water content is 15% to obtain dried sludge;
s1-2, placing the dried sludge obtained in the step S1-1 into a roasting furnace, roasting at the temperature of 300 ℃ for 20min in the air atmosphere, naturally cooling, crushing, and sieving by a 20-mesh sieve to obtain sludge particles to be leached;
s2, acid leaching:
s2-1, preparing a sulfuric acid solution with the mass concentration of 5%, and then mixing the sulfuric acid solution with the sludge particles to be leached obtained in the step S1-2 according to the volume ratio of 5:1 to obtain a mixture A;
s2-2, heating the mixture A obtained in the step S2-1 to 30 ℃, and then carrying out ultrasonic treatment for 20min at the frequency of 22kHz and the power of 630W to obtain a mixture B; finally, filtering the mixture B to obtain a filtrate;
s2-3, standing the filtrate obtained in the step S2-2 for 45min, and extracting supernatant to obtain leachate;
s3, enriching chromium elements:
s3-1, adding 5% ethanol solution into the leachate obtained in the step S2-3, stirring and mixing uniformly, then introducing into a gasification box, and carrying out gasification treatment at the temperature of 250 ℃ to obtain gas-phase chromium elements;
s3-2, introducing the gas-phase chromium element obtained in the step S3-1 into a ferrous sulfate heptahydrate solution with the mass concentration of 15% to react for 30min, forming trivalent chromium precipitate, and separating the trivalent chromium precipitate.
Example 2
The embodiment describes a selective extraction and recovery device for chromium in electroplating sludge, which is suitable for the selective extraction and recovery device for chromium in electroplating sludge in the embodiment 1, and comprises dehydration equipment for deep dehydration of electroplating sludge, a roasting furnace for roasting treatment of dried sludge, and a gasification box for gasification treatment of a mixed solution of leachate and an ethanol solution, wherein the dehydration equipment comprises an outer shell 1, a lifting component 2, an extrusion dehydration component 3 and a controller; a water collecting tank 10 is arranged at the lower end of the outer shell 1, the water collecting tank 10 is communicated with the inside of the outer shell 1, and a drain pipe 11 is arranged on the side wall of the water collecting tank 10;
the lifting assembly 2 comprises a lifting sleeve 20 and two lifting motors 21, the lifting sleeve 20 is movably sleeved inside the outer shell 1, the outer part of the lifting sleeve 20 is rotatably clamped with a first connecting sleeve 200 at a lower position, the first connecting sleeve 200 is fixedly connected with the inner wall of the outer shell 1, the two lifting motors 21 are arranged, the two lifting motors 21 are symmetrically arranged at two sides inside the outer shell 1 through mounting rings 210 and are positioned at the upper end of the first connecting sleeve 200, lifting screw rods 211 are arranged on output shafts of the lifting motors 21, and the two lifting screw rods 211 respectively penetrate through the mounting rings 210 and are respectively in threaded connection with the first connecting sleeve 200;
the squeezing and dewatering component 3 comprises a dewatering cylinder 30, a squeezing motor 31, a squeezing plate 32 and a driving motor 34, wherein the dewatering cylinder 30 is sleeved inside a lifting sleeve 20, the upper end of the dewatering cylinder 30 is open, the lower end of the dewatering cylinder is clamped with a movable plate 33, a plurality of water outlet holes 300 are arranged on the side wall in a penetrating manner, two second connecting sleeves 301 are rotatably clamped on the side wall of the dewatering cylinder 30, the two second connecting sleeves 301 are respectively and fixedly connected with the inner wall of the lifting sleeve 20, the squeezing plate 32 is slidably clamped at the opening at the upper end of the dewatering cylinder 30, the squeezing motor 31 is arranged at the top of the outer shell 1, a squeezing screw 310 is arranged on an output shaft of the squeezing motor 31, the squeezing screw 310 penetrates through the squeezing plate 32 and then is rotatably clamped with the bottom inside the dewatering cylinder 30, and the squeezing screw 310 is in threaded connection with the squeezing plate 32; the movable plate 33 is connected with the top of the water collecting tank 10 through a shaft rod 330, a connecting gear 331 is sleeved on the shaft rod 330, the driving motor 34 is arranged at the top of the water collecting tank 10, and a driving gear 340 meshed with the connecting gear 331 is arranged on an output shaft of the driving motor 34;
the controller is respectively electrically connected with the lifting motor 21, the extrusion motor 31 and the driving motor 34; the controller, the lifting motor 21, the extruding motor 31 and the driving motor 34 are all commercially available products.
Example 3
A method for selectively extracting and recovering chromium element in electroplating sludge comprises the following steps:
s1, pretreatment of electroplating sludge:
s1-1, introducing the electroplating sludge into a dehydration device, performing pressure maintaining dehydration treatment for 40min under the pressure of 2.1MPa, and drying until the water content is 16% to obtain dried sludge;
s1-2, placing the dried sludge obtained in the step S1-1 into a roasting furnace, roasting for 36min at 480 ℃ in an air atmosphere, naturally cooling, crushing, and sieving with a 45-mesh sieve to obtain sludge particles to be leached; putting sludge particles to be leached into a drier, and drying for 25min at 880 ℃; by carrying out drying treatment on sludge particles to be leached, organic matters and combustible impurities in the sludge particles to be leached can be effectively removed, the separation difficulty of chromium elements in electroplating sludge is reduced, and the extraction efficiency of the chromium elements is improved;
s2, acid leaching:
s2-1, preparing a sulfuric acid solution with the mass concentration of 9%, and then mixing the sulfuric acid solution with the dried sludge particles to be leached obtained in the step S1-2 according to the volume ratio of 7:1 to obtain a mixture A;
s2-2, heating the mixture A obtained in the step S2-1 to 65 ℃, and then carrying out ultrasonic treatment for 40min at the frequency of 28kHz and the power of 725W to obtain a mixture B; finally, filtering the mixture B to obtain a filtrate;
s2-3, standing the filtrate obtained in the step S2-2 for 68min, and extracting supernatant to obtain leachate;
s3, enriching chromium elements:
s3-1, adding 9% ethanol solution into the leachate obtained in the step S2-3, stirring and mixing uniformly, then introducing into a gasification box, and carrying out gasification treatment at 360 ℃ to obtain gas-phase chromium elements;
s3-2, introducing the gas-phase chromium element obtained in the step S3-1 into a ferrous sulfate heptahydrate solution with the mass concentration of 19% to react for 42min, forming trivalent chromium precipitate, and separating the trivalent chromium precipitate.
Example 4
The embodiment describes a device for selectively extracting and recovering chromium elements from electroplating sludge, which is suitable for embodiment 3, and comprises dehydration equipment for deeply dehydrating the electroplating sludge, a roasting furnace for roasting dried sludge, and a gasification box for gasifying a mixed solution of leachate and an ethanol solution, wherein the dehydration equipment comprises an outer shell 1, a lifting component 2, an extrusion dehydration component 3 and a controller; the lower end of the outer shell 1 is provided with a water collecting tank 10, the water collecting tank 10 is communicated with the inside of the outer shell 1, and the side wall of the water collecting tank 10 is provided with a drain pipe 11;
the lifting assembly 2 comprises a lifting sleeve 20 and two lifting motors 21, the lifting sleeve 20 is movably sleeved inside the outer shell 1, the outer part of the lifting sleeve 20 is rotatably clamped with a first connecting sleeve 200 at a lower position, the first connecting sleeve 200 is fixedly connected with the inner wall of the outer shell 1, the two lifting motors 21 are arranged, the two lifting motors 21 are symmetrically arranged at two sides inside the outer shell 1 through mounting rings 210 and are positioned at the upper end of the first connecting sleeve 200, lifting screw rods 211 are arranged on output shafts of the lifting motors 21, and the two lifting screw rods 211 respectively penetrate through the mounting rings 210 and are respectively in threaded connection with the first connecting sleeve 200;
the squeezing and dewatering component 3 comprises a dewatering cylinder 30, a squeezing motor 31, a squeezing plate 32 and a driving motor 34, wherein the dewatering cylinder 30 is sleeved inside a lifting sleeve 20, the upper end of the dewatering cylinder 30 is open, the lower end of the dewatering cylinder is clamped with a movable plate 33, a plurality of water outlet holes 300 are arranged on the side wall in a penetrating manner, two second connecting sleeves 301 are rotatably clamped on the side wall of the dewatering cylinder 30, the two second connecting sleeves 301 are respectively and fixedly connected with the inner wall of the lifting sleeve 20, the squeezing plate 32 is slidably clamped at the opening at the upper end of the dewatering cylinder 30, a vibrating plate 320 is slidably clamped on the squeezing plate 32, a curved surface vibrating sleeve 321 is arranged on the upper end surface of the vibrating plate 320, a mounting plate 311 is sleeved on a squeezing screw 310, a squeezing roller 312 is rotatably clamped at the lower end of the mounting plate 311, and the squeezing roller 312 is abutted against the upper end surface of the curved surface vibrating sleeve 321; a sliding rod 3200 is arranged at the joint of the vibrating plate 320 and the extrusion plate 32, a return spring 3201 is sleeved on the sliding rod 3200, the upper end of the return spring 3201 is abutted against the vibrating plate 320, the lower end of the return spring 3201 is abutted against the extrusion plate 32, and the mounting plate 311 and the extrusion roller 312 are driven to rotate in the rotating process of the extrusion screw 310, so that the vibrating plate 320 reciprocates up and down under the action of the extrusion roller 312, the vibrating extrusion dehydration of the electroplating sludge is realized, and the dehydration efficiency of the electroplating sludge is improved; the extrusion motor 31 is arranged at the top of the outer shell 1, an extrusion screw 310 is arranged on an output shaft of the extrusion motor 31, the extrusion screw 310 penetrates through the extrusion plate 32 and then is rotationally clamped with the bottom in the dewatering cylinder 30, and the extrusion screw 310 is in threaded connection with the extrusion plate 32; the movable plate 33 is connected with the top of the water collecting tank 10 through a shaft rod 330, a connecting gear 331 is sleeved on the shaft rod 330, the driving motor 34 is arranged at the top of the water collecting tank 10, and a driving gear 340 meshed with the connecting gear 331 is arranged on an output shaft of the driving motor 34;
the controller is respectively electrically connected with the lifting motor 21, the extrusion motor 31 and the driving motor 34; the controller, the lifting motor 21, the extruding motor 31 and the driving motor 34 are all commercially available products.
Example 5
A method for selectively extracting and recovering chromium element in electroplating sludge comprises the following steps:
s1, pretreatment of electroplating sludge:
s1-1, introducing the electroplating sludge into a dehydration device, carrying out pressure maintaining dehydration treatment for 55min under the pressure of 2.5MPa, and drying until the water content is 14% to obtain dried sludge;
s1-2, placing the dried sludge obtained in the step S1-1 into a roasting furnace, roasting for 45min at 780 ℃ in an air atmosphere, naturally cooling, crushing, and sieving with a 50-mesh sieve to obtain sludge particles to be leached;
s2, acid leaching:
s2-1, preparing a sulfuric acid solution with the mass concentration of 11%, and then mixing the sulfuric acid solution with the sludge particles to be leached obtained in the step S1-2 according to the volume ratio of 8:1 to obtain a mixture A;
s2-2, heating the mixture A obtained in the step S2-1 to 90 ℃, and then carrying out ultrasonic treatment for 60min at the frequency of 35kHz and the power of 880W to obtain a mixture B; finally, filtering the mixture B to obtain a filtrate;
s2-3, standing the filtrate obtained in the step S2-2 for 85min, and extracting supernatant to obtain leachate;
s3, enriching chromium elements:
s3-1, adding 13% ethanol solution into the leachate obtained in the step S2-3, stirring and mixing uniformly, then introducing into a gasification box, and carrying out gasification treatment at 480 ℃ to obtain gas-phase chromium elements;
s3-2, introducing the gas-phase chromium element obtained in the step S3-1 into 23% ferrous sulfate heptahydrate solution by mass concentration to react for 55min to form trivalent chromium precipitate, and separating the trivalent chromium precipitate; firstly, carrying out adsorption treatment on a ferrous sulfate heptahydrate solution by using ion exchange resin, then desorbing the ion exchange resin by using a sodium carbonate aqueous solution with the mass concentration of 12%, and separating precipitates in a desorption solution; the suspended chromium element in the ferrous sulfate heptahydrate solution can be effectively extracted by carrying out ion exchange resin adsorption treatment on the ferrous sulfate heptahydrate solution; drying the trivalent chromium precipitate at 90 ℃ to constant weight, and then ball-milling into granules with the grain diameter of 0.5-1.5 mm; the trivalent chromium precipitate is dried and ball-milled, so that the collection and utilization of chromium materials are facilitated.
Example 6
The embodiment describes a selective extraction and recovery device for chromium in electroplating sludge, which is suitable for the embodiment 5, and comprises dehydration equipment for deep dehydration of the electroplating sludge, a roasting furnace for roasting treatment of dried sludge, and a gasification box for gasification treatment of a mixed solution of leachate and an ethanol solution, wherein the dehydration equipment comprises an outer shell 1, a lifting component 2, an extrusion dehydration component 3 and a controller; a water collecting tank 10 is arranged at the lower end of the outer shell 1, the water collecting tank 10 is communicated with the inside of the outer shell 1, and a drain pipe 11 is arranged on the side wall of the water collecting tank 10;
the lifting assembly 2 comprises a lifting sleeve 20 and two lifting motors 21, the lifting sleeve 20 is movably sleeved inside the outer shell 1, the outer part of the lifting sleeve 20 is rotatably clamped with a first connecting sleeve 200 at a lower position, the first connecting sleeve 200 is fixedly connected with the inner wall of the outer shell 1, the two lifting motors 21 are arranged, the two lifting motors 21 are symmetrically arranged at two sides inside the outer shell 1 through mounting rings 210 and are positioned at the upper end of the first connecting sleeve 200, lifting screw rods 211 are arranged on output shafts of the lifting motors 21, and the two lifting screw rods 211 respectively penetrate through the mounting rings 210 and are respectively in threaded connection with the first connecting sleeve 200; the installation ring 210 is provided with a guide rod 2100, the guide rod 2100 is in sliding clamping connection with the outer wall of the lifting sleeve 20, and the guide rod 2100 is arranged, so that the stability of the lifting sleeve 20 during movement is improved, and the operation stability of the whole dewatering device is improved;
the squeezing and dewatering component 3 comprises a dewatering cylinder 30, a squeezing motor 31, a squeezing plate 32 and a driving motor 34, the dewatering cylinder 30 is sleeved inside the lifting sleeve 20, the upper end of the dewatering cylinder 30 is open, the lower end of the dewatering cylinder is clamped with a movable plate 33, a plurality of water outlet holes 300 are arranged on the side wall in a penetrating manner, two second connecting sleeves 301 are rotatably clamped on the side wall of the dewatering cylinder 30, the two second connecting sleeves 301 are respectively and fixedly connected with the inner wall of the lifting sleeve 20, the squeezing plate 32 is slidably clamped at the upper end opening of the dewatering cylinder 30, a vibrating plate 320 is slidably clamped on the squeezing plate 32, a curved surface vibrating sleeve 321 is arranged on the upper end surface of the vibrating plate 320, a mounting plate 311 is sleeved on a squeezing screw 310, a squeezing roller 312 is rotatably clamped at the lower end of the mounting plate 311, and the squeezing roller 312 is abutted to the upper end surface of the curved surface vibrating sleeve 321; a sliding rod 3200 is arranged at the joint of the vibrating plate 320 and the extrusion plate 32, a return spring 3201 is sleeved on the sliding rod 3200, the upper end of the return spring 3201 is abutted against the vibrating plate 320, the lower end of the return spring 3201 is abutted against the extrusion plate 32, and the mounting plate 311 and the extrusion roller 312 are driven to rotate in the rotating process of the extrusion screw 310, so that the vibrating plate 320 reciprocates up and down under the action of the extrusion roller 312, the vibrating extrusion dehydration of the electroplating sludge is realized, and the dehydration efficiency of the electroplating sludge is improved; the extrusion motor 31 is arranged at the top of the outer shell 1, an extrusion screw 310 is arranged on an output shaft of the extrusion motor 31, the extrusion screw 310 penetrates through the extrusion plate 32 and then is rotationally clamped with the bottom in the dewatering cylinder 30, and the extrusion screw 310 is in threaded connection with the extrusion plate 32; the movable plate 33 is connected with the top of the water collecting tank 10 through a shaft rod 330, a connecting gear 331 is sleeved on the shaft rod 330, the driving motor 34 is arranged at the top of the water collecting tank 10, and a driving gear 340 meshed with the connecting gear 331 is arranged on an output shaft of the driving motor 34; the upper end of the water collecting tank 10 is provided with the protecting sleeve 12, the upper end of the protecting sleeve 12 is rotationally clamped with the lower end face of the movable plate 33, the driving motor 34 is positioned in the protecting sleeve 12, and the influence of sludge on the meshing effect of the connecting gear 331 and the driving gear 340 can be avoided by arranging the protecting sleeve 12;
the controller is respectively electrically connected with the lifting motor 21, the extrusion motor 31 and the driving motor 34; the controller, the lifting motor 21, the extruding motor 31 and the driving motor 34 are all commercially available products.
Example 7
A method for selectively extracting and recovering chromium element in electroplating sludge comprises the following steps:
s1, pretreatment of electroplating sludge:
s1-1, introducing the electroplating sludge into a dehydration device, performing pressure maintaining dehydration treatment for 30min under the pressure of 1.8MPa, and drying until the water content is 16% to obtain dried sludge;
s1-2, placing the dried sludge obtained in the step S1-1 into a roasting furnace, roasting at 780 ℃ for 20min in an air atmosphere, naturally cooling, crushing, and sieving with a 20-mesh sieve to obtain sludge particles to be leached;
s2, acid leaching:
s2-1, preparing a sulfuric acid solution with the mass concentration of 5%, and then mixing the sulfuric acid solution with the sludge particles to be leached obtained in the step S1-2 according to the volume ratio of 5:1 to obtain a mixture A;
s2-2, heating the mixture A obtained in the step S2-1 to 30 ℃, and then carrying out ultrasonic treatment for 20min at the frequency of 22kHz and the power of 630W to obtain a mixture B; finally, filtering the mixture B to obtain a filtrate;
s2-3, standing the filtrate obtained in the step S2-2 for 45min, and extracting supernatant to obtain leachate; introducing the leachate into a high-pressure reaction kettle, controlling the temperature of the high-pressure reaction kettle at 280 ℃ and the pressure at 3MPa, continuously reacting for 10min, and discharging the high-pressure reaction kettle to obtain hydrothermal leachate; by carrying out hydrothermal treatment on the leachate, the viscous organic matters in the leachate can be decomposed, the colloid structure in the leachate can be destroyed, and the enrichment efficiency of the chromium element is improved;
s3, enriching chromium elements:
s3-1, adding an ethanol solution with the concentration of 5% of the hydrothermal leachate obtained in the step S2-3, stirring and mixing uniformly, then introducing into a gasification box, and carrying out gasification treatment at the temperature of 250 ℃ to obtain a gas-phase chromium element;
s3-2, introducing the gas-phase chromium element obtained in the step S3-1 into a ferrous sulfate heptahydrate solution with the mass concentration of 15% to react for 30min, forming trivalent chromium precipitate, and separating the trivalent chromium precipitate.
Example 8
The embodiment describes a selective extraction and recovery device for chromium in electroplating sludge, which is suitable for the embodiment 7, and comprises a dehydration device for deep dehydration of the electroplating sludge, a roasting furnace for roasting treatment of dried sludge, and a gasification box for gasification treatment of a mixed solution of leachate and an ethanol solution, wherein the dehydration device comprises an outer shell 1, a lifting component 2, an extrusion dehydration component 3 and a controller; the lower end of the outer shell 1 is provided with a water collecting tank 10, the water collecting tank 10 is communicated with the inside of the outer shell 1, and the side wall of the water collecting tank 10 is provided with a drain pipe 11;
the lifting assembly 2 comprises a lifting sleeve 20 and two lifting motors 21, the lifting sleeve 20 is movably sleeved inside the outer shell 1, the outer part of the lifting sleeve 20 is rotatably clamped with a first connecting sleeve 200 at a lower position, the first connecting sleeve 200 is fixedly connected with the inner wall of the outer shell 1, the two lifting motors 21 are arranged, the two lifting motors 21 are symmetrically arranged at two sides inside the outer shell 1 through mounting rings 210 and are positioned at the upper end of the first connecting sleeve 200, lifting screw rods 211 are arranged on output shafts of the lifting motors 21, and the two lifting screw rods 211 respectively penetrate through the mounting rings 210 and are respectively in threaded connection with the first connecting sleeve 200; the installation ring 210 is provided with a guide rod 2100, the guide rod 2100 is in sliding clamping connection with the outer wall of the lifting sleeve 20, and the guide rod 2100 is arranged, so that the stability of the lifting sleeve 20 during movement is improved, and the operation stability of the whole dewatering device is improved;
the squeezing and dewatering component 3 comprises a dewatering cylinder 30, a squeezing motor 31, a squeezing plate 32 and a driving motor 34, wherein the dewatering cylinder 30 is sleeved inside a lifting sleeve 20, the upper end of the dewatering cylinder 30 is open, the lower end of the dewatering cylinder is clamped with a movable plate 33, a plurality of water outlet holes 300 are arranged on the side wall in a penetrating manner, two second connecting sleeves 301 are rotatably clamped on the side wall of the dewatering cylinder 30, the two second connecting sleeves 301 are respectively and fixedly connected with the inner wall of the lifting sleeve 20, the squeezing plate 32 is slidably clamped at the opening at the upper end of the dewatering cylinder 30, a vibrating plate 320 is slidably clamped on the squeezing plate 32, a curved surface vibrating sleeve 321 is arranged on the upper end surface of the vibrating plate 320, a mounting plate 311 is sleeved on a squeezing screw 310, a squeezing roller 312 is rotatably clamped at the lower end of the mounting plate 311, and the squeezing roller 312 is abutted against the upper end surface of the curved surface vibrating sleeve 321; a sliding rod 3200 is arranged at the joint of the vibrating plate 320 and the extrusion plate 32, a return spring 3201 is sleeved on the sliding rod 3200, the upper end of the return spring 3201 is abutted against the vibrating plate 320, the lower end of the return spring 3201 is abutted against the extrusion plate 32, and the mounting plate 311 and the extrusion roller 312 are driven to rotate in the rotating process of the extrusion screw 310, so that the vibrating plate 320 reciprocates up and down under the action of the extrusion roller 312, the vibrating extrusion dehydration of the electroplating sludge is realized, and the dehydration efficiency of the electroplating sludge is improved; the extrusion motor 31 is arranged at the top of the outer shell 1, an extrusion screw 310 is arranged on an output shaft of the extrusion motor 31, the extrusion screw 310 penetrates through the extrusion plate 32 and then is rotationally clamped with the bottom in the dewatering cylinder 30, and the extrusion screw 310 is in threaded connection with the extrusion plate 32; the movable plate 33 is connected with the top of the water collecting tank 10 through a shaft rod 330, a connecting gear 331 is sleeved on the shaft rod 330, the driving motor 34 is arranged at the top of the water collecting tank 10, and a driving gear 340 meshed with the connecting gear 331 is arranged on an output shaft of the driving motor 34; the upper end of the water collecting tank 10 is provided with the protecting sleeve 12, the upper end of the protecting sleeve 12 is rotationally clamped with the lower end face of the movable plate 33, the driving motor 34 is positioned in the protecting sleeve 12, and the protecting sleeve 12 is arranged, so that the influence of sludge on the meshing effect of the connecting gear 331 and the driving gear 340 can be avoided;
the controller is respectively electrically connected with the lifting motor 21, the extrusion motor 31 and the driving motor 34; the controller, the lifting motor 21, the extruding motor 31 and the driving motor 34 are all commercially available products.
Example 9: a method for selectively extracting and recovering chromium element in electroplating sludge comprises the following steps:
s1, pretreatment of electroplating sludge:
s1-1, introducing the electroplating sludge into a dehydration device, carrying out pressure maintaining dehydration treatment for 55min under the pressure of 2.5MPa, and drying until the water content is 15% to obtain dried sludge;
s1-2, placing the dried sludge obtained in the step S1-1 into a roasting furnace, roasting for 45min at 780 ℃ in an air atmosphere, naturally cooling, crushing, and sieving with a 50-mesh sieve to obtain sludge particles to be leached;
s2, acid leaching:
s2-1, preparing a sulfuric acid solution with the mass concentration of 11%, and then mixing the sulfuric acid solution with the sludge particles to be leached obtained in the step S1-2 according to the volume ratio of 8:1 to obtain a mixture A; adding 5 volume percent of hydrogen peroxide solution with the volume concentration of 4 percent into the mixture A, and reacting for 45min at the temperature of 125 ℃; by adding the hydrogen peroxide solution into the mixture A, the conversion efficiency of hexavalent chromium in the mixture A can be improved, new metal ions cannot be introduced, and the extraction efficiency of chromium elements in electroplating sludge is improved.
S2-2, heating the mixture A processed in the step S2-1 to 90 ℃, and then carrying out ultrasonic treatment for 60min at the frequency of 35kHz and the power of 880W to obtain a mixture B; finally, filtering the mixture B to obtain a filtrate;
s2-3, standing the filtrate obtained in the step S2-2 for 85min, and extracting supernatant to obtain leachate;
s3, enriching chromium elements:
s3-1, adding 13% ethanol solution into the leachate obtained in the step S2-3, stirring and mixing uniformly, then introducing into a gasification box, and carrying out gasification treatment at 480 ℃ to obtain gas-phase chromium elements;
and S3-2, introducing the gas-phase chromium element obtained in the step S3-1 into 23% ferrous sulfate heptahydrate solution by mass concentration to react for 55min to form trivalent chromium precipitate, and separating the trivalent chromium precipitate.
Example 10
The embodiment describes a selective extraction and recovery device for chromium in electroplating sludge, which is suitable for the embodiment 9, and comprises a dehydration device for deep dehydration of the electroplating sludge, a roasting furnace for roasting treatment of dried sludge, and a gasification box for gasification treatment of a mixed solution of leachate and an ethanol solution, wherein the dehydration device comprises an outer shell 1, a lifting component 2, an extrusion dehydration component 3 and a controller; the lower end of the outer shell 1 is provided with a water collecting tank 10, the water collecting tank 10 is communicated with the inside of the outer shell 1, and the side wall of the water collecting tank 10 is provided with a drain pipe 11;
the lifting assembly 2 comprises a lifting sleeve 20 and two lifting motors 21, the lifting sleeve 20 is movably sleeved inside the outer shell 1, the outer part of the lifting sleeve 20 is rotatably clamped with a first connecting sleeve 200 at a lower position, the first connecting sleeve 200 is fixedly connected with the inner wall of the outer shell 1, the two lifting motors 21 are arranged, the two lifting motors 21 are symmetrically arranged at two sides inside the outer shell 1 through mounting rings 210 and are positioned at the upper end of the first connecting sleeve 200, lifting screw rods 211 are arranged on output shafts of the lifting motors 21, and the two lifting screw rods 211 respectively penetrate through the mounting rings 210 and are respectively in threaded connection with the first connecting sleeve 200; the installation ring 210 is provided with a guide rod 2100, the guide rod 2100 is in sliding clamping connection with the outer wall of the lifting sleeve 20, and the guide rod 2100 is arranged, so that the stability of the lifting sleeve 20 during movement is improved, and the operation stability of the whole dewatering device is improved;
the squeezing and dewatering component 3 comprises a dewatering cylinder 30, a squeezing motor 31, a squeezing plate 32 and a driving motor 34, wherein the dewatering cylinder 30 is sleeved inside a lifting sleeve 20, the upper end of the dewatering cylinder 30 is open, the lower end of the dewatering cylinder is clamped with a movable plate 33, a plurality of water outlet holes 300 are arranged on the side wall in a penetrating manner, two second connecting sleeves 301 are rotatably clamped on the side wall of the dewatering cylinder 30, the two second connecting sleeves 301 are respectively and fixedly connected with the inner wall of the lifting sleeve 20, the squeezing plate 32 is slidably clamped at the opening at the upper end of the dewatering cylinder 30, a vibrating plate 320 is slidably clamped on the squeezing plate 32, a curved surface vibrating sleeve 321 is arranged on the upper end surface of the vibrating plate 320, a mounting plate 311 is sleeved on a squeezing screw 310, a squeezing roller 312 is rotatably clamped at the lower end of the mounting plate 311, and the squeezing roller 312 is abutted against the upper end surface of the curved surface vibrating sleeve 321; a sliding rod 3200 is arranged at the joint of the vibrating plate 320 and the extrusion plate 32, a return spring 3201 is sleeved on the sliding rod 3200, the upper end of the return spring 3201 is abutted against the vibrating plate 320, the lower end of the return spring 3201 is abutted against the extrusion plate 32, and the mounting plate 311 and the extrusion roller 312 are driven to rotate in the rotating process of the extrusion screw 310, so that the vibrating plate 320 reciprocates up and down under the action of the extrusion roller 312, the vibrating extrusion dehydration of the electroplating sludge is realized, and the dehydration efficiency of the electroplating sludge is improved; the extrusion motor 31 is arranged at the top of the outer shell 1, an extrusion screw 310 is arranged on an output shaft of the extrusion motor 31, the extrusion screw 310 penetrates through the extrusion plate 32 and then is rotationally clamped with the bottom in the dewatering cylinder 30, and the extrusion screw 310 is in threaded connection with the extrusion plate 32; the movable plate 33 is connected with the top of the water collecting tank 10 through a shaft rod 330, a connecting gear 331 is sleeved on the shaft rod 330, the driving motor 34 is arranged at the top of the water collecting tank 10, and a driving gear 340 meshed with the connecting gear 331 is arranged on an output shaft of the driving motor 34; the upper end of the water collecting tank 10 is provided with the protecting sleeve 12, the upper end of the protecting sleeve 12 is rotationally clamped with the lower end face of the movable plate 33, the driving motor 34 is positioned in the protecting sleeve 12, and the protecting sleeve 12 is arranged, so that the influence of sludge on the meshing effect of the connecting gear 331 and the driving gear 340 can be avoided;
the controller is respectively electrically connected with the lifting motor 21, the extrusion motor 31 and the driving motor 34; the controller, the lifting motor 21, the extruding motor 31 and the driving motor 34 are all commercially available products.
Example 11
A method for selectively extracting and recovering chromium element in electroplating sludge comprises the following steps:
s1, pretreatment of electroplating sludge:
s1-1, introducing the electroplating sludge into a dehydration device, performing pressure maintaining dehydration treatment at the pressure of 2.5MPa for 55min, and drying until the water content is 13% to obtain dried sludge;
s1-2, placing the dried sludge obtained in the step S1-1 into a roasting furnace, roasting for 45min at 780 ℃ in an air atmosphere, naturally cooling, crushing, and sieving with a 50-mesh sieve to obtain sludge particles to be leached; putting sludge particles to be leached into a drier, and carrying out drying treatment at 1050 ℃ for 45 min; by carrying out drying treatment on sludge particles to be leached, organic matters and combustible impurities in the sludge particles to be leached can be effectively removed, the separation difficulty of chromium elements in electroplating sludge is reduced, and the extraction efficiency of the chromium elements is improved;
s2, acid leaching:
s2-1, preparing a sulfuric acid solution with the mass concentration of 11%, and then mixing the sulfuric acid solution with the sludge particles to be leached obtained in the step S1-2 after drying treatment according to the volume ratio of 8:1 to obtain a mixture A; adding 11% by volume of 9% hydrogen peroxide solution into the mixture A, and reacting at 185 deg.C for 60 min; by adding the hydrogen peroxide solution into the mixture A, the conversion efficiency of hexavalent chromium in the mixture A can be improved, new metal ions cannot be introduced, and the extraction efficiency of chromium elements in electroplating sludge is improved;
s2-2, heating the mixture A processed in the step S2-1 to 90 ℃, and then carrying out ultrasonic treatment for 60min at the frequency of 35kHz and the power of 880W to obtain a mixture B; finally, filtering the mixture B to obtain a filtrate;
s2-3, standing the filtrate obtained in the step S2-2 for 85min, and extracting supernatant to obtain leachate; introducing the leachate into a high-pressure reaction kettle, controlling the temperature of the high-pressure reaction kettle at 350 ℃ and the pressure at 6MPa, continuously reacting for 25min, and discharging the high-pressure reaction kettle to obtain hydrothermal leachate; by carrying out hydrothermal treatment on the leachate, the viscous organic matters in the leachate can be decomposed, the colloid structure in the leachate can be destroyed, and the enrichment efficiency of the chromium element is improved;
s3, enriching chromium elements:
s3-1, adding a 13% ethanol solution into the hydrothermal leaching solution obtained in the step S2-3, uniformly stirring and mixing, then introducing into a gasification box, and carrying out gasification treatment at 480 ℃ to obtain a gas-phase chromium element;
s3-2, introducing the gas-phase chromium element obtained in the step S3-1 into 23% ferrous sulfate heptahydrate solution by mass concentration to react for 55min to form trivalent chromium precipitate, and separating the trivalent chromium precipitate; firstly, carrying out adsorption treatment on a ferrous sulfate heptahydrate solution by using ion exchange resin, then desorbing the ion exchange resin by using a sodium carbonate aqueous solution with the mass concentration of 18%, and separating precipitates in a desorption solution; the suspended chromium element in the ferrous sulfate heptahydrate solution can be effectively extracted by carrying out ion exchange resin adsorption treatment on the ferrous sulfate heptahydrate solution; finally, drying the trivalent chromium precipitate at the temperature of 120 ℃ to constant weight, and then ball-milling the trivalent chromium precipitate into granules with the grain diameter of 1.5-1.8 mm; the trivalent chromium precipitate is dried and ball-milled, so that the collection and utilization of chromium materials are facilitated.
Example 12
The embodiment describes a device for selectively extracting and recovering chromium elements from electroplating sludge, which is suitable for the embodiment 11, and comprises a dehydration device for deeply dehydrating the electroplating sludge, a roasting furnace for roasting dried sludge, and a gasification box for gasifying a mixed solution of leachate and an ethanol solution, wherein the dehydration device comprises an outer shell 1, a lifting component 2, an extrusion dehydration component 3 and a controller; the lower end of the outer shell 1 is provided with a water collecting tank 10, the water collecting tank 10 is communicated with the inside of the outer shell 1, and the side wall of the water collecting tank 10 is provided with a drain pipe 11;
the lifting assembly 2 comprises a lifting sleeve 20 and two lifting motors 21, the lifting sleeve 20 is movably sleeved inside the outer shell 1, the outer part of the lifting sleeve 20 is rotatably clamped with a first connecting sleeve 200 at a lower position, the first connecting sleeve 200 is fixedly connected with the inner wall of the outer shell 1, the two lifting motors 21 are arranged, the two lifting motors 21 are symmetrically arranged at two sides inside the outer shell 1 through mounting rings 210 and are positioned at the upper end of the first connecting sleeve 200, lifting screw rods 211 are arranged on output shafts of the lifting motors 21, and the two lifting screw rods 211 respectively penetrate through the mounting rings 210 and are respectively in threaded connection with the first connecting sleeve 200; the installation ring 210 is provided with a guide rod 2100, the guide rod 2100 is in sliding clamping connection with the outer wall of the lifting sleeve 20, and the guide rod 2100 is arranged, so that the stability of the lifting sleeve 20 during movement is improved, and the operation stability of the whole dewatering device is improved;
the squeezing and dewatering component 3 comprises a dewatering cylinder 30, a squeezing motor 31, a squeezing plate 32 and a driving motor 34, wherein the dewatering cylinder 30 is sleeved inside a lifting sleeve 20, the upper end of the dewatering cylinder 30 is open, the lower end of the dewatering cylinder is clamped with a movable plate 33, a plurality of water outlet holes 300 are arranged on the side wall in a penetrating manner, two second connecting sleeves 301 are rotatably clamped on the side wall of the dewatering cylinder 30, the two second connecting sleeves 301 are respectively and fixedly connected with the inner wall of the lifting sleeve 20, the squeezing plate 32 is slidably clamped at the opening at the upper end of the dewatering cylinder 30, a vibrating plate 320 is slidably clamped on the squeezing plate 32, a curved surface vibrating sleeve 321 is arranged on the upper end surface of the vibrating plate 320, a mounting plate 311 is sleeved on a squeezing screw 310, a squeezing roller 312 is rotatably clamped at the lower end of the mounting plate 311, and the squeezing roller 312 is abutted against the upper end surface of the curved surface vibrating sleeve 321; a sliding rod 3200 is arranged at the joint of the vibrating plate 320 and the extrusion plate 32, a return spring 3201 is sleeved on the sliding rod 3200, the upper end of the return spring 3201 is abutted against the vibrating plate 320, the lower end of the return spring 3201 is abutted against the extrusion plate 32, and the mounting plate 311 and the extrusion roller 312 are driven to rotate in the rotating process of the extrusion screw 310, so that the vibrating plate 320 reciprocates up and down under the action of the extrusion roller 312, the vibrating extrusion dehydration of the electroplating sludge is realized, and the dehydration efficiency of the electroplating sludge is improved; the extrusion motor 31 is arranged at the top of the outer shell 1, an extrusion screw 310 is arranged on an output shaft of the extrusion motor 31, the extrusion screw 310 penetrates through the extrusion plate 32 and then is rotationally clamped with the bottom in the dewatering cylinder 30, and the extrusion screw 310 is in threaded connection with the extrusion plate 32; the movable plate 33 is connected with the top of the water collecting tank 10 through a shaft rod 330, a connecting gear 331 is sleeved on the shaft rod 330, the driving motor 34 is arranged at the top of the water collecting tank 10, and a driving gear 340 meshed with the connecting gear 331 is arranged on an output shaft of the driving motor 34; the upper end of the water collecting tank 10 is provided with the protecting sleeve 12, the upper end of the protecting sleeve 12 is rotationally clamped with the lower end face of the movable plate 33, the driving motor 34 is positioned in the protecting sleeve 12, and the protecting sleeve 12 is arranged, so that the influence of sludge on the meshing effect of the connecting gear 331 and the driving gear 340 can be avoided;
the controller is respectively electrically connected with the lifting motor 21, the extrusion motor 31 and the driving motor 34; the controller, the lifting motor 21, the extruding motor 31 and the driving motor 34 are all commercially available products.
Test examples
The methods of the embodiments 1, 3, 5, 7, 9 and 11 of the invention are respectively used for extracting and recovering chromium elements in electroplating sludge discharged by certain electroplating plants in northern China, and the chromium elements in the electroplating sludge are measured after the treatment is finished, and the results are shown in table 1:
TABLE 1 influence of examples on the extraction efficiency of chromium from electroplating sludge
As can be seen from the data in table 1, in example 3, compared with example 1, by performing drying treatment on sludge particles to be leached, organic matters and combustible impurities in the sludge particles to be leached can be effectively removed, the separation difficulty of chromium in electroplating sludge is reduced, and the extraction efficiency of chromium is improved; example 5 compared with example 1, by subjecting the ferrous sulfate heptahydrate solution to ion exchange resin adsorption treatment, suspended chromium elements in the ferrous sulfate heptahydrate solution can be effectively extracted; drying and ball milling treatment are carried out on the trivalent chromium precipitate, so that collection and utilization of chromium materials are facilitated; example 7 compared with example 1, by performing hydrothermal treatment on the leachate, the viscous organic matter in the leachate can be decomposed, and the colloidal structure in the leachate can be destroyed, so that the enrichment efficiency of the chromium element can be improved; example 9 compared with example 1, the conversion efficiency of hexavalent chromium in the mixture a can be improved by adding the hydrogen peroxide solution into the mixture a, and the extraction efficiency of chromium element in the electroplating sludge is improved without introducing new metal ions; in example 11, compared with examples 1, 3, 5, 7 and 9, the precipitation rate and extraction rate of chromium in the electroplating sludge are both in the best state by integrating and optimizing the favorable conditions, so that the resource utilization of the electroplating sludge is realized, and the economic efficiency is improved.
Claims (9)
1. The method for selectively extracting and recovering chromium element in electroplating sludge is characterized by comprising the following steps:
s1, pretreatment of electroplating sludge:
s1-1, introducing the electroplating sludge into a dewatering device, carrying out pressure-maintaining dewatering treatment for 30-55 min under the pressure of 1.8-2.5 MPa, and drying until the water content is less than 20% to obtain dried sludge;
s1-2, placing the dried sludge obtained in the step S1-1 into a roasting furnace, roasting at the temperature of 300-780 ℃ for 20-45 min in the air atmosphere, naturally cooling, crushing, and sieving with a 20-50-mesh sieve to obtain sludge particles to be leached;
s2, acid leaching:
s2-1, preparing a sulfuric acid solution with the mass concentration of 5-11%, and then mixing the sulfuric acid solution with the sludge particles to be leached obtained in the step S1-2 according to the volume ratio of 5-8: 1 to obtain a mixture A;
s2-2, heating the mixture A obtained in the step S2-1 to 30-90 ℃, and then carrying out ultrasonic treatment for 20-60 min at the frequency of 22-35 kHz and the power of 630-880W to obtain a mixture B; finally, filtering the mixture B to obtain a filtrate;
s2-3, standing the filtrate obtained in the step S2-2 for 45-85 min, and extracting supernatant to obtain leachate;
s3, enriching chromium elements:
s3-1, adding an ethanol solution with the concentration of 5-13% into the leachate obtained in the step S2-3, stirring and mixing uniformly, then introducing into a gasification box, and carrying out gasification treatment at the temperature of 250-480 ℃ to obtain a gas-phase chromium element;
s3-2, introducing the gas-phase chromium element obtained in the step S3-1 into a ferrous sulfate heptahydrate solution with the mass concentration of 15-23% to react for 30-55 min, forming trivalent chromium precipitate, and separating the trivalent chromium precipitate.
2. The method for selectively extracting and recovering chromium from electroplating sludge according to claim 1, wherein after the step S1-2 is completed, the sludge particles to be leached are placed into a drying machine, and drying treatment is carried out at 880-1050 ℃ for 25-45 min.
3. The method for selectively extracting and recovering chromium elements from electroplating sludge according to claim 1, wherein after the step S3-2 is completed, firstly, the ferrous sulfate heptahydrate solution is adsorbed by using ion exchange resin, then, the ion exchange resin is desorbed by using a sodium carbonate aqueous solution with the mass concentration of 12-18%, and the precipitate in the desorption solution is separated.
4. The method for selectively extracting and recovering chromium element from electroplating sludge according to claim 1, wherein after the step S2-3 is completed, the leachate is introduced into a high-pressure reaction kettle, the temperature of the high-pressure reaction kettle is controlled to be 280-350 ℃, the pressure of the high-pressure reaction kettle is controlled to be 3-6 MPa, the reaction is continued for 10-25 min, and the hydrothermal leachate is obtained after the high-pressure reaction kettle is discharged.
5. The method for selectively extracting and recovering chromium element from electroplating sludge according to claim 1, wherein after the step S3-2 is completed, the trivalent chromium precipitate is dried to constant weight at 90-120 ℃, and then is ball-milled into particles with the diameter less than 2 mm.
6. The method for selectively extracting and recovering the chromium element from the electroplating sludge according to claim 1, wherein after the step S2-1 is completed, a hydrogen peroxide solution with a volume concentration of 4-9% and a volume concentration of 5-11% of the mixture A is added into the mixture A, and the mixture A is reacted at a temperature of 125-185 ℃ for 45-60 min.
7. An apparatus for selectively extracting and recovering chromium from electroplating sludge, which is used for the method according to any one of claims 1-6, and is characterized by comprising a dewatering device for deeply dewatering the electroplating sludge, a roasting furnace for roasting dried sludge, and a gasification box for gasifying a mixed solution of leachate and ethanol solution, wherein the dewatering device comprises an outer shell (1), a lifting assembly (2), an extrusion dewatering assembly (3) and a controller; a water collecting tank (10) is arranged at the lower end of the outer shell (1), the water collecting tank (10) is communicated with the inside of the outer shell (1), and a drain pipe (11) is arranged on the side wall of the water collecting tank (10);
the lifting assembly (2) comprises a lifting sleeve (20) and lifting motors (21), the lifting sleeve (20) is movably sleeved inside the outer shell (1), the outer part of the lifting sleeve (20) is rotatably clamped with a first connecting sleeve (200) by the lower position, the first connecting sleeve (200) is fixedly connected with the inner wall of the outer shell (1), the lifting motors (21) are provided with two, the two lifting motors (21) are symmetrically arranged on two sides inside the outer shell (1) through mounting rings (210) and are positioned at the upper end of the first connecting sleeve (200), lifting screw rods (211) are arranged on output shafts of the lifting motors (21), and the two lifting screw rods (211) respectively penetrate through the mounting rings (210) and are respectively in threaded connection with the first connecting sleeve (200);
the squeezing and dewatering component (3) comprises a dewatering cylinder (30), a squeezing motor (31), a squeezing plate (32) and a driving motor (34), the dewatering cylinder (30) is sleeved inside a lifting sleeve (20), the upper end of the dewatering cylinder (30) is provided with an opening, a movable plate (33) is clamped at the lower end of the dewatering cylinder (30), a plurality of water outlet holes (300) are arranged on the side wall of the dewatering cylinder in a penetrating manner, two second connecting sleeves (301) are connected to the side wall of the dewatering cylinder (30) in a rotating and clamping manner, the two second connecting sleeves (301) are respectively fixedly connected with the inner wall of the lifting sleeve (20), the squeezing plate (32) is clamped at the opening at the upper end of the dewatering cylinder (30) in a sliding manner, the squeezing motor (31) is arranged at the top of the outer shell (1), a squeezing lead screw (310) is arranged on an output shaft of the squeezing motor (31), and the squeezing lead screw (310) is connected with the bottom of the dewatering cylinder (30) in a rotating manner after penetrating through the squeezing plate (32), the extrusion screw rod (310) is in threaded connection with the extrusion plate (32); the movable plate (33) is connected with the top of the water collecting tank (10) through a shaft rod (330), a connecting gear (331) is sleeved on the shaft rod (330), the driving motor (34) is arranged at the top of the water collecting tank (10), and a driving gear (340) meshed with the connecting gear (331) is arranged on an output shaft of the driving motor (34);
the controller is respectively and electrically connected with the lifting motor (21), the extrusion motor (31) and the driving motor (34).
8. The device for selectively extracting and recovering chromium from electroplating sludge according to claim 7, wherein a vibrating plate (320) is slidably clamped on the extrusion plate (32), a curved vibrating sleeve (321) is arranged on the upper end surface of the vibrating plate (320), a mounting plate (311) is sleeved on the extrusion lead screw (310), an extrusion roller (312) is rotatably clamped on the lower end of the mounting plate (311), and the extrusion roller (312) is abutted against the upper end surface of the curved vibrating sleeve (321); the vibrating plate (320) is provided with slide bar (3200) with stripper plate (32) junction, the cover is equipped with reset spring (3201) on slide bar (3200), reset spring (3201) upper end and vibrating plate (320) butt, lower extreme and stripper plate (32) butt.
9. The device for selectively extracting and recovering chromium from electroplating sludge according to claim 7, wherein the mounting ring (210) is provided with a guide rod (2100), and the guide rod (2100) is in sliding clamping connection with the outer wall of the lifting sleeve (20).
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| CN114517261B (en) | 2023-04-25 |
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