Device for extracting basic chromium sulfate from leather-making chrome tanning waste liquid

Abstract

The utility model discloses a device for extracting basic chromium sulfate from leather-making chrome tanning waste liquid, which belongs to the field of wastewater treatment and recycling, and is characterized in that trivalent chromium in the chrome tanning waste liquid is enriched and purified by using amphoteric ion exchange fibers according to the ion exchange principle, so that the total chromium discharge in the treated chrome tanning waste liquid is stable and reaches the standard, and meanwhile, the basic chromium sulfate is extracted from the leather-making chrome tanning waste liquid. The basic chromium sulfate concentrated solution is obtained through regeneration and is reused in the processes of pickling, tanning and the like, and the tanning production requirement is met. According to the device, the loss of chromium is greatly reduced, the production cost of an enterprise is reduced, secondary pollution is avoided, and the device has a good popularization prospect.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of wastewater treatment and recycling, especially relates to a device for treating and recycling chrome tanning wastewater, which is suitable for efficiently extracting basic chromium sulfate from chrome tanning wastewater in a leather-making enterprise. BACKGROUND

[0002] The leather-making industry not only brings economic benefits and meets people's needs, but also causes serious pollution to the environment, especially to water resources. Chrome tanning is one of the important methods for tanning leather. Since chrome tanning can endow leather with excellent properties, most of the leather is tanned with chrome. However, in the traditional tanning process, the effective utilization rate of chrome is relatively low, generally only 60%-70%, and the remaining 30%-40% of the chrome remains in the wastewater, with a chromium content of 2000-5000 mg / L as Cr2O3. The discharge of chrome tanning wastewater not only causes great waste of resources, but also causes serious pollution to the ecological environment. Therefore, the treatment of chrome tanning wastewater has always been a problem that must be solved in the leather-making industry.

[0003] At present, several common methods for treating chrome tanning wastewater include alkali precipitation, recycling, extraction, and chemical method. The first two methods are relatively mature, but have limitations: first, the alkali precipitation method requires a large area, a large amount of chemicals, and is difficult to stabilize and meet the standards; second, it produces a large amount of waste chromium residue, which may cause secondary pollution if not properly treated; third, the metal chromium cannot be effectively recovered, resulting in waste of resources. SUMMARY

[0004] In view of the above problems, the utility model discloses a device for extracting basic chromium sulfate from chrome tanning wastewater.

[0005] In order to achieve the above object, the technical scheme adopted by the utility model is as follows: a device for extracting basic chromium sulfate from tanning chromium tanning waste liquid, characterized by comprising a wastewater collection tank capable of collecting chromium tanning waste liquid, a first booster pump, an MCR membrane tank, a second booster pump, a primary ion exchange column, a relay water tank, a third booster pump, a secondary ion exchange column, an acid storage barrel, an alkali storage barrel, a water storage barrel, a fourth booster pump, and a concentrated liquid storage barrel; a water inlet of the primary ion exchange column is sequentially communicated with a water outlet of the wastewater collection tank through pipelines, and a water outlet of the primary ion exchange column is sequentially communicated with a water inlet of the secondary ion exchange column through pipelines; water outlets of the acid storage barrel, the alkali storage barrel, and the water storage barrel are respectively communicated with a water inlet of the fourth booster pump through pipelines, a water outlet of the fourth booster pump is respectively communicated with water outlets of the primary ion exchange column and the secondary ion exchange column through pipelines, and water inlets of the primary ion exchange column and the secondary ion exchange column are respectively communicated with a water inlet of the concentrated liquid storage barrel through pipelines.

[0006] Preferably, a wastewater collecting pipe is connected to the wastewater collection tank and is used to discharge the chromium tanning waste liquid filtered by the 3-5 mm grating machine into the tank.

[0007] Preferably, a backwashing device is arranged on the MCR membrane tank, and the MCR membrane tank is provided with MCR membranes with a pore size of 0.1-0.4 μm.

[0008] The above preferred scheme has the beneficial effect that the MCR membranes can be backwashed with acid liquid according to actual needs, effectively avoiding the clogging of the MCR membranes, prolonging the service life of the MCR membranes, and reducing the maintenance or replacement cost.

[0009] Preferably, the primary ion exchange column and the secondary ion exchange column are composed of multiple ion exchange columns, the top of the ion exchange column is provided with a pressure gauge and a compressed air inlet, the inside of the ion exchange column is filled with a kind of amphoteric ion exchange fiber containing -COOH and -NH2 functional groups, and in order to reduce the resistance of liquid flow, the inside of the ion exchange column adopts a multi-layer filling structure, and the multiple layers are separated by a perforated sieve plate, and the perforated sieve plate is uniformly provided with small holes with a pore size of 2-4 mm.

[0010] Preferably, a dosing device for adding sodium hydroxide and sulfuric acid into the tank, a pH meter, and an aeration stirring device are arranged on the relay water tank.

[0011] Preferably, the acid storage barrel and the alkali storage barrel are provided with an aeration stirring device.

[0012] Preferably, the first booster pump, the second booster pump, the third booster pump, and the fourth booster pump are horizontal multi-stage centrifugal pumps.

[0013] Preferably, an adjustable valve capable of controlling the flow of liquid in the pipe is arranged on each of the pipes.

[0014] The above preferred embodiment has the advantage that the flow of liquid in the pipe can be adjusted according to actual conditions to meet the needs of different occasions, and is more convenient to use.

[0015] Compared with the prior art, the ion exchange column of the utility model is filled with a kind of zwitterionic ion exchange fiber, which is a fibrous ion exchange material developed on the basis of ion exchange resin.Ion exchange fiber is an ion exchanger with fibrous material as the skeleton, and ion exchange groups mostly exist on the surface of the filament.In the ion exchange process, ion exchange fiber reduces the penetration process of ions in the particles compared with ion exchange resin, greatly improving the speed of ion exchange.Zwitterionic ion exchange fiber has the characteristics of large specific surface area, fast exchange speed, high regeneration efficiency and strong anti-pollution ability, and also has selective adsorption function for trivalent chromium.The zwitterionic ion exchange fiber contains weak acid and weak base groups such as carboxyl and amine groups on the surface of the filament, which can ionize in solution and produce exchangeable ions.In a certain pH range, trivalent chromium ions exchange with the ions ionized from the zwitterionic ion exchange fiber, and are adsorbed on the surface of the fiber.Compared with sodium ions, calcium ions and magnesium ions, the zwitterionic ion exchange fiber has stronger selective adsorption capacity for trivalent chromium ions, reducing the influence of other ions on the adsorption of trivalent chromium by the zwitterionic ion exchange fiber, thereby achieving adsorption and purification effect.After the zwitterionic ion exchange fiber is saturated, the alkaline chromium sulfate concentrate is obtained by regeneration and is used for pickling and tanning processes to meet the normal tanning production requirements. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The figure is a structural schematic diagram of the device of the utility model.

[0017] In the drawings, the component list represented by each reference numeral is as follows:

[0018] 1, wastewater collection tank, 2, first booster pump, 3, MCR membrane tank, 4, second booster pump, 5, primary ion exchange column, 6, relay water tank, 7, third booster pump, 8, secondary ion exchange column, 9, acid storage barrel, 10, alkali storage barrel, 11, water storage barrel, 12, fourth booster pump, 13, concentrated liquid storage barrel.

[0019] Figure 2 It is the section view of ion exchange column.

[0020] In the drawings, the component list represented by each reference numeral is as follows:

[0021] 14, perforated sieve plate, 15, pressure gauge, 16, compressed air inlet. Detailed Implementation

[0022] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0023] Example

[0024] An apparatus for extracting basic chromium sulfate from chrome tanning wastewater includes a wastewater collection tank (1) for collecting chrome tanning wastewater, a first booster pump (2), an MCR membrane tank (3), a second booster pump (4), a primary ion exchange column (5), a relay water tank (6), a third booster pump (7), a secondary ion exchange column (8), an acid storage tank (9), an alkali storage tank (10), a water storage tank (11), a fourth booster pump (12), and a concentrate storage tank (13). The inlet of the primary ion exchange column (5) is connected in sequence to the outlet of the second booster pump (4), the MCR membrane tank (3), the first booster pump (2), and the wastewater collection tank (1) via pipelines. The outlet of the primary ion exchange column (5) is connected to the inlet of the intermediate water tank (6), the third booster pump (7), and the secondary ion exchange column (8) in sequence through pipes; the outlets of the acid storage tank (9), the alkali storage tank (10), and the water storage tank (11) are connected to the inlet of the fourth booster pump (12) through pipes respectively; the outlet of the fourth booster pump (12) is connected to the outlet of the primary ion exchange column (5) and the secondary ion exchange column (8) through pipes respectively; and the inlets of the primary ion exchange column (5) and the secondary ion exchange column (8) are connected to the inlet of the concentrate storage tank (13) through pipes respectively.

[0025] The wastewater collection tank (1) is connected to a wastewater manifold that discharges chromium tanning waste liquid filtered by a 3-5mm bar screen into the tank.

[0026] The MCR membrane tank (3) is equipped with a backwashing device, and the MCR membrane tank (3) contains an MCR membrane with a pore size of 0.1-0.4μm. Acid can be used to backwash the MCR membrane as needed, effectively preventing clogging, extending its service life, and reducing maintenance or replacement costs.

[0027] The primary ion exchange column (5) and the secondary ion exchange column (8) are composed of multi-stage ion exchange columns. The top of the ion exchange column is equipped with a pressure gauge (15) and a compressed air inlet (16). The inside is filled with an amphoteric ion exchange fiber containing two functional groups, -COOH and -NH2. In order to reduce the resistance of liquid flow, the ion exchange column adopts a multi-layer filling structure. Each layer is separated by a porous sieve plate (14). The porous sieve plate (14) has small holes with a diameter of 2-4 mm evenly distributed on it.

[0028] The relay pool (6) is provided with a dosing device for adding sodium hydroxide and sulfuric acid into the pool, a pH meter and an aeration stirring device.

[0029] The acid storage barrel (9) and the alkali storage barrel (10) are provided with aeration stirring devices.

[0030] The first lifting pump (2), the second lifting pump (4), the third lifting pump (7) and the fourth lifting pump (12) are horizontal multi-stage centrifugal pumps.

[0031] Adjusting valves capable of controlling the flow of liquid in the pipes are arranged on all the pipes.

[0032] The utility model discloses a method for extracting basic chromium sulfate from chrome tanning waste liquid by ion exchange technology, which is simple and convenient to operate and does not cause secondary pollution. First, insoluble impurities in the waste liquid are filtered out by a pretreatment system, and then the impurity-removed chrome tanning waste liquid is adsorbed by a first ion exchange column, and then the adsorbed waste liquid is added into a relay barrel, and acid is added to adjust the pH value of the waste liquid, and then the adjusted waste liquid is continuously added into a second ion exchange column for standard treatment, and the total chromium concentration in the effluent is always less than 0.5 mg / L, which fully meets the standard. The ion exchange column saturated with adsorption is regenerated by sulfuric acid and sodium hydroxide to obtain a concentrated solution of basic chromium sulfate, and the concentrated solution of basic chromium sulfate obtained for multiple times is provided to a leather production enterprise, and is used for pickling, tanning and other processes, which can meet the normal production requirements.

[0033] The utility model discloses a product can according to the actual situation of wastewater, set up multiple ion exchange column parallel, series mode operation, at the same time for reducing the resistance of liquid flow, the ion exchange fiber column inside adopts multilayer filling structure. The amphoteric ion exchange fiber filled in the ion exchange column is a fibrous ion exchange material developed on the basis of ion exchange resin. The ion exchange fiber is an ion exchanger with fibrous material as the skeleton, and ion exchange groups mostly exist on the filament surface. In the ion exchange process, the ion exchange fiber reduces the penetration process of ions in the particles relative to the ion exchange resin, greatly improving the ion exchange speed. The amphoteric ion exchange fiber has the characteristics of large specific surface area, fast exchange speed, high regeneration efficiency, strong anti-pollution ability and the like, and also has selective adsorption function for trivalent chromium. The amphoteric ion exchange fiber contains ionizable weak acid and weak alkaline groups such as carboxyl and amine groups on the filament surface, which can ionize in the solution and produce exchangeable ions. Trivalent chromium ions exist in the form of basic chromium sulfate in the solution within a certain pH range, and can exchange with the ions ionized from the amphoteric ion exchange fiber, so as to be adsorbed on the fiber surface. Relative to sodium ions, calcium ions and magnesium ions, the amphoteric ion exchange fiber has stronger selective adsorption capacity for trivalent chromium ions, reducing the influence of other ions on the adsorption of trivalent chromium by the amphoteric ion exchange fiber, so as to achieve the adsorption and purification effect. After the amphoteric ion exchange fiber is saturated, the basic chromium sulfate concentrate is obtained through regeneration and is returned to the pickling and tanning processes, meeting the normal tanning production requirements.

[0034] It is apparent for those skilled in the art that the utility model is not limited to the details of the above-mentioned exemplary embodiments, and can be realized in other specific forms without departing from the spirit or essential characteristics of the utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the utility model is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims should be included in the utility model, and any figure reference in the claims should not be regarded as limiting the claims.

[0035] The above only describes the preferred embodiments of the utility model, and is not used to limit the utility model, and any modification, equivalent replacement, improvement and the like made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A device for extracting basic chromium sulfate from chrome tanning effluents, characterized in that, The wastewater collection tank (1) includes a chromium tanning waste liquid that can be collected, a first lifting pump (2), an MCR membrane tank (3), a second lifting pump (4), a first ion exchange column (5), a relay water tank (6), a third lifting pump (7), a second ion exchange column (8), an acid storage barrel (9), an alkali storage barrel (10), a water storage barrel (11), a fourth lifting pump (12), and a concentrated liquid storage barrel (13). The water inlet of the first ion exchange column (5) is sequentially communicated with the water outlets of the second lifting pump (4), the MCR membrane tank (3), the first lifting pump (2), and the wastewater collection tank (1) through pipelines. The water outlets of the acid storage barrel (9), the alkali storage barrel (10), and the water storage barrel (11) are respectively communicated with the water inlets of the fourth lifting pump (12) through pipelines.

2. A device for extracting basic chromium sulfate from chrome tanning effluent according to claim 1, characterized in that, The wastewater collection tank (1) is connected with a wastewater collecting pipe for discharging the chromium tanning waste liquid filtered by a 3-5 mm grating machine into the tank.

3. A device for extracting basic chromium sulfate from chrome tanning effluent according to claim 1, characterized in that, The MCR membrane tank (3) is provided with a backwashing device, and the MCR membrane tank (3) is provided with MCR membranes with a pore size of 0.1-0.4 μm.

4. A device for extracting basic chromium sulfate from chrome tanning effluent according to claim 1, characterized in that, The first ion exchange column (5) and the second ion exchange column (8) are composed of multiple ion exchange columns, the top of the ion exchange column is provided with a pressure gauge (15) and a compressed air inlet (16), the inside is filled with a zwitterionic exchange fiber containing -COOH and -NH2 two functional groups, and in order to reduce the resistance of liquid flow, a multi-layer filling structure is adopted inside the ion exchange column, and a perforated sieve plate (14) is used to separate each layer, and the perforated sieve plate (14) is uniformly distributed with small holes with a pore size of 2-4 mm.

5. A device for extracting basic chromium sulfate from chrome tanning effluent according to claim 1, characterized in that, The relay water tank (6) is provided with a dosing device for adding sodium hydroxide and sulfuric acid into the tank, a pH meter, and an aeration stirring device.

6. A device for extracting basic chromium sulfate from chrome tanning effluent according to claim 1, characterized in that, The acid storage barrel (9) and the alkali storage barrel (10) are provided with an aeration stirring device.

7. A device for extracting basic chromium sulfate from chrome tanning effluent according to claim 1, characterized in that, The first lifting pump (2), the second lifting pump (4), the third lifting pump (7), and the fourth lifting pump (12) are horizontal multi-stage centrifugal pumps.

8. A device for extracting basic chromium sulfate from tannery chrome tanning effluents according to any one of claims 1-7, characterized in that, All the pipelines are provided with adjustable valves that can control the flow of liquid in the pipelines.

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