JP7024632B2 - Sedimentation tank and its control method, and solid material manufacturing method - Google Patents

Description

The present invention relates to a settling tank for recovering leaked solids contained in the filtrate discharged from various filtration steps and a control method thereof. The present invention also relates to a method for producing a solid substance by extracting the solid substance contained in the liquid to be treated from the liquid to be treated.

In the electrolytic purification of copper, a blister copper plate containing impurities is used as an anode (anode), and a thin plate made of pure copper, stainless steel, titanium, etc. is used as a cathode (cathode), and the anode and the cathode are alternately charged into the electrolytic tank to be constant. An electrolytic solution whose temperature is controlled in the range is supplied to the electrolytic tank and energized, and copper having a predetermined thickness is electrodeposited on the cathode to obtain electrolytic copper.

When energized, the copper contained in the anode elutes into the electrolytic solution as copper ions. At the same time, impurities such as arsenic, bismuth, antimony, and nickel contained in the anode are also eluted in the electrolytic solution. Only copper ions in the electrolytic solution are electrodeposited on the cathode to obtain high-purity electrolytic copper, but impurities remain in the electrolytic solution, and as a result, the impurity concentration of the electrolytic solution increases.

When the concentration of impurities in the electrolytic solution increases with the progress of electrolytic refining, the impurities coagulate with copper to lower the copper grade of electrolytic copper, cause scale in the piping of the electrolytic solution, and hinder the operation. , Problems such as lowering the electrical conductivity of the electrolytic solution and increasing the power cost arise.

Therefore, a part of the electrolytic solution is sent to the purification process to remove impurities, and then the electrolytic cell is supplied again to the electrolytic cell. In the purification step, the electrolytic solution is vacuum-evaporated and concentrated, and the oversaturated copper is precipitated and removed as crude copper sulfate by quenching, and then the concentration and cooling steps are performed, and then the crude copper sulfate is recovered. From the copper-removing electrolytic step of removing residual copper, arsenic, bismuth, and antimon from the crude mother liquor, which is a filtrate, by precipitating it on the cathode, and from the copper-removing final solution, which is a nickel-containing solution after copper removal. , Copper sulfate is separated and recovered as crude nickel sulfate, and a denicking process is performed.

In the nickel removal step, first, a pre-heated decopper final solution is supplied to a nickel concentrating tank, and in this nickel concentrating tank, a graphite electrode is immersed in the decopper final solution to energize the copper. The final liquid is heated and concentrated by Joule heat. Next, the heat-concentrated concentrate is sent to a cooling crystal tank, and crude nickel sulfate is precipitated from this concentrate due to the common ion effect associated with the increase in sulfuric acid concentration due to concentration and the decrease in solubility due to cooling. Further, the slurry containing the precipitated nickel sulphate is sent to a filter by a cooling crystal tank pump, the nickel sulphate is recovered as a solid by filtration, and the filtrate is sucked by a vacuum pump and stored in a receiver tank. , Disbursed as appropriate.

In this way, not only in the step of recovering the crude nickel sulfate, but also in the step of recovering the object which has become a solid by solidifying using the difference in solubility, the concentrated liquid heated and concentrated is generally used in the cooling crystal tank. The solid matter is precipitated by the decrease in solubility due to cooling after concentration, and the slurry in which the solid matter is precipitated is supplied to the filtration step. In the filtration step, the slurry is separated into a solid substance (residue) and a filtrate by a filter medium such as a filter cloth, a filter paper, and a mesh screen. In particular, in suction filtration such as vacuum filtration, separation can be performed quickly by sucking the filtrate by depressurizing the filtrate side of the filter medium. The sucked filtrate is stored in the receiver tank and discharged as appropriate.

The filtrate to be discharged contains an object that is in a dissolved state due to its solubility and a fine solid substance (fine crude nickel sulfate in the denickelization step) that has leaked from the filter, and these are recovery losses. Is the cause of.

In order to reduce filtration leakage, it is conceivable to make the filter medium finer, but this method reduces the filtration rate, so if the capacity of the filter is not sufficient, the production of solid matter will decrease. The problem arises.

As in the technique described in JP-A-2009-114520, there is also a method of returning a part of the filtrate from the receiver tank to the cooling crystal tank. In this method, the more the amount of the filtrate returned is increased, the more fine solid matter leaked from the filtrate can be recovered. In the absence of, there arises the problem of reduced solids production. Further, when the entire filtrate is returned, the amount processed by the filter continues to increase with time, so that only a part of the filtrate can be returned from the receiver tank. As described above, it is difficult to sufficiently recover the fine solid matter leaked from the filtrate from the filter.

Japanese Unexamined Patent Publication No. 2009-114520

An object of the present invention is to provide a means for improving the recovery rate of a solid substance in a filtration step and reducing the production cost of the solid substance by recovering the fine solid substance leaked from the filter. It is in.

As a result of various studies to solve the above problems, the present inventors provided a settling tank on the downstream side of the filter to settle and separate the filtrate containing the fine solid matter leaked from the filter. It was found that the fine solids can be efficiently recovered by precipitating the fine solids.

In addition, as a result of various studies on the shape and control of the settling tank, by devising the shape of the bottom of the settling tank and providing means capable of appropriately controlling the extraction of the supernatant and the extraction of the bottom of the solid matter. , It was found that the fine solid matter that leaked from the filtrate can be recovered more efficiently.

The present inventors have completed the present invention based on these findings.

The settling tank of the present invention is connected to a tank body, a bottom, an inlet for receiving a filtrate, an outlet for extracting the supernatant, an outlet for removing the bottom of solid matter provided at the bottom, and an outlet for extracting the supernatant. A means for supplying the filtrate through the in-tank pipe and the filtrate receiving inlet, and a means for extracting the supernatant generated by the sedimentation separation of the filtrate through the in-tank pipe and the supernatant extraction outlet. And a means for bottoming out the solid matter settled by the sedimentation separation of the filtrate via the solid matter bottoming out outlet.

In particular, the settling tank of the present invention further includes a non-contact level sensor and a timer arranged so as to be able to sense the level of the filtrate in the settling tank.

The bottom portion is tilted downward toward the outlet for removing the bottom of the solid material. It is preferable that the bottom portion has an inclination angle of 40 degrees or more from the horizontal plane.

The solid material bottoming outlet is arranged at the bottom of the bottom.

The in-tank pipe extends from the supernatant extraction outlet to the horizontal intermediate portion and the height intermediate portion of the bottom portion, and has an opening at the lower end portion. If necessary, the in-tank piping is located between the supernatant extraction outlet and the upper end of the bottom so as not to interfere with the range sensed by the non-contact level sensor in the cross section of the tank body. It is preferable to be arranged.

The non-contact level sensor operates a means for supplying the filtrate until the level of the filtrate reaches the upper limit of accepting the filtrate in the tank, and the filtrate is settled and separated, and the supernatant is separated. After the operation of the means for extracting the supernatant, the level of the supernatant is detected.

The timer is activated when the level of the supernatant reaches the upper end of the bottom portion, and is a means for extracting the supernatant when a predetermined time elapses before the level of the supernatant reaches the opening of the pipe in the tank. The operation is stopped, and the means for bottoming out the solid matter is operated, and after a lapse of a predetermined time, the means for bottoming out the solid matter is stopped.

Each of the means for supplying the filtrate, the means for extracting the supernatant, and the means for extracting the bottom of the solid matter is known to include piping and a vacuum pump, a metering pump, a line pump, and other known pumps. It consists of a fluid transfer device.

The non-contact level sensor is selected from an ultrasonic level sensor, a radio wave level sensor, and a laser level sensor.

The bottom portion preferably has a cone shape or a mortar shape.

As the method for controlling the settling tank of the present invention, the above-mentioned settling tank of the present invention is used.

In particular, in the method for controlling the settling tank of the present invention,
A step of receiving the filtrate by the means for supplying the filtrate and stopping the acceptance of the filtrate when the non-contact level sensor detects the upper limit of the filtrate acceptance in the tank.
A step of precipitating and separating the filtrate in the settling tank and settling the solid matter on the bottom.
When the supernatant is started to be extracted by the means for extracting the supernatant, the non-contact level sensor detects the level of the supernatant, and the timer reaches the upper end of the bottom. A step of operating and stopping the extraction of the supernatant when a predetermined time elapses before the level of the supernatant reaches the opening of the pipe in the tank.
At the same time as the extraction of the supernatant is stopped, the bottoming out of the solid matter is started by means for bottoming out the solid matter, and after a predetermined time has elapsed after the start of bottoming out of the solid matter, the bottoming out of the solid matter is performed. The process of stopping,
To prepare for.

The method for producing a solid substance of the present invention is
A concentration process in which the liquid to be treated is heated and concentrated to obtain a concentrated liquid,
A cooling step of cooling the concentrate to precipitate a solid substance and obtaining a slurry containing the solid substance.
A filtration step of filtering the slurry to recover the solid matter,
The filtrate containing the solid matter obtained in the filtration step and leaked from filtration is put into a settling tank, and the solid matter in the filtrate is settled at the bottom of the settling tank and settled at the bottom of the settling tank. The process of extracting the solidified material and repeating it before the cooling process,
To prepare for.

In particular, in the solid matter recovery method of the present invention, the control method of the settling tank of the present invention is used in the step using the settling tank.

Two or more of the settling tanks are provided, and the filtrate is charged into any one of the settling tanks, and the solid matter is settled and / or extracted in at least one of the settling tanks. It is preferable to perform and at the same time.

According to the present invention, a filtrate containing fine solids leaked from a filter is retained in a settling tank for a predetermined time, so that the fine solids are settled at the bottom of the settling tank by sedimentation separation and settled. By repeating the solid matter settled at the bottom of the tank in a cooling crystal tank or a concentration tank, through grain growth, and filtering again, the solid matter is suppressed from being discharged to the outside of the system, and the solid matter is efficiently solidified. Can be recovered. Therefore, it is possible to dramatically improve the recovery rate of the solid matter from the liquid to be treated and reduce the manufacturing cost per solid matter.

FIG. 1 is an equipment flow diagram showing a solid matter recovery device of the present invention. FIG. 2 is a schematic cross-sectional view showing the settling tank of the present invention.

The present invention relates to a step of recovering a solid substance from a liquid to be treated, such as a denickel step of separating and recovering nickel as crude nickel sulfate from the decopperating final liquid in electrolytic refining of copper. In such a step of recovering a solid substance from a liquid to be treated, as shown in FIG. 1, basically, a concentration tank 1 for heating and concentrating the liquid to be treated 6 to obtain a concentrate 7 and a concentration tank 1 are used. The concentrated liquid 7 sent from 1 is cooled to precipitate the solid matter 9, and the cooling crystal tank 2 for obtaining the slurry 8 containing the solid matter 9 and the slurry 8 are filtered to recover the solid matter 9. A filter 3 is provided.

Any concentrating tank can be applied to the concentrating tank 1 as long as the liquid to be treated 6 can be heated at a temperature equal to or higher than the boiling point of the liquid to be treated 6. For example, an electric evaporator is applicable. In the electric evaporation tank, a graphite electrode rod that can be energized and is immersed in the liquid to be treated is inserted and arranged in the tank, and the liquid to be treated 6 is energized through the graphite electrode rod to be treated. The liquid 6 is heated by Joule heat to evaporate the water content to obtain a concentrated liquid 7. The heating temperature depends on the type of the liquid to be treated, but in the case of the decopperating final liquid, it is preferably a temperature in the range of about 150 ° C to 200 ° C. In addition, as the concentrating tank 1, a structure capable of heating the liquid to be treated directly or indirectly from the periphery of the tank by using a heavy oil burner can be adopted.

Also in the cooling crystal tank 2, the concentrated solution 7 is cooled to a temperature at which the solid substance 9 is sufficiently precipitated, for example, about 50 ° C. in the case of recovery of crude nickel sulfate, depending on the type of solute contained in the concentrated solution 7. Any possible structure can be taken. For example, a structure in which a jacket or a serpentine tube is installed around or in the tank and a refrigerant is passed through them is applicable to the cooling crystal tank 2.

As for the filter 3, a filter using natural filtration, vacuum filtration, pressure filtration, centrifugal filtration, or the like can be used. Further, as the filter medium used in the filter 3, a filter cloth, a filter paper, a mesh screen or the like can be used. As the filter 3, for example, a vacuum filter, a centrifuge, a centrifuge, or the like can be used, but in the case of recovery of crude nickel sulfate, a vacuum filter is usually applied as the filter 3. ing.

In the case of a vacuum filter, the solid substance 9 such as crude nickel sulfate is recovered in the filter 3, and the filtrate 10 is sucked into the vacuum pump, usually stored in the receiver tank 4, and discharged as appropriate.

The present invention is characterized in that a settling tank 5 is provided in place of or in addition to the receiver tank 4 provided in the conventional apparatus. The filtrate 10 containing the fine solid matter 9a that has leaked from the filter 3 is charged into the settling tank 5 directly or via the receiver tank 4, and the fine solid matter 9a is settled on the bottom 14 of the settling tank 5. Then, the solid material 9a settled in the bottom 14 of the settling tank 5 is bottomed out and repeated in the cooling crystal tank 2 or the concentration tank 1.

Conventionally, the filtrate 10 sent from the filter 3 is stored in the receiver tank 4, and the entire amount of the filtrate 10 is discharged as appropriate, or a part of the filtrate 10 is returned to the cooling crystal tank 2 as it is. On the other hand, in the present invention, the filtrate 10 is held in the settling tank 5 for a sufficient time to precipitate the fine solid matter 9a, and the settled solid matter 9a is bottomed out to form a cooling crystal tank 2 or a concentration tank. It can be returned to No. 1 and only the supernatant 11 produced by the precipitation of the solid substance 9a can be once discharged out of the system and added to the electrolytic solution to be used for adjusting the acid concentration or the like. As a result, mainly fine solids 9a can be effectively recovered by in-system circulation without excessively supplying the cooling crystal tank 2 or the concentration tank 1, and the solids from the liquid to be treated 6 can be recovered. The recovery rate of goods has been dramatically improved.

As shown in FIG. 2, the basic structure of the settling tank 5 according to an example of the embodiment of the present invention is a tank body 13, a bottom 14 on which fine solids 9a settle, a filter 3 or a receiver tank 4. It is connected to an inlet 15 for receiving a filtrate for receiving the filtrate 10 from the upstream side such as, an outlet 16 for extracting the supernatant, an outlet 17 for removing the solid bottom provided at the bottom 14, and an outlet 16 for extracting the supernatant. The in-tank pipe 18, the means 20 for supplying the filtrate to the filtrate receiving inlet 15, the means 21 for extracting the supernatant 11 after the filtrate 10 is settled and separated from the supernatant extraction outlet 16, and the means for removing the bottom of the solid matter. A means 12 for bottoming out the solid substance 9a settled from the outlet 17 is provided.

The overall shape and size of the settling tank 5 may basically be a size according to the surrounding equipment and the like as long as the bottom portion 14 is tilted downward toward the outlet 17 for removing the bottom of the solid material. , Arbitrary. The bottom portion 14, which is tilted downward toward the outlet 17 for removing the bottom of the solid material, has a shape that narrows toward the bottom. With such a shape of the bottom 14, the ratio of the volume occupied by the portion directly above the outlet 17 for removing the bottom of the solid material from the volume of the bottom 14 increases, so that the precipitated solid material 9a is extracted from the outlet 17 for removing the bottom of the solid material. It is advantageous for.

The inclination of the bottom 14 of the settling tank 5 is such that the inclination angle from the horizontal plane is 40 degrees or more, preferably 45 degrees or more, so that the solid material 9a settled on the bottom 14 can be quickly brought to the bottom of the bottom 14. It is possible to smoothly bottom out the precipitated solid substance 9a. On the other hand, regarding the inclination of the bottom portion 14, when the inclination angle from the horizontal plane is less than 40 degrees, it takes time for the solid matter 9a settled on the bottom portion 14 to flow to the bottommost portion of the bottom portion 14, and the settled solid matter 9a Depending on the particle shape, it may deposit on the bottom surface of the bottom portion 14. When the solid matter 9a is deposited on the bottom 14 of the settling tank 5, the tank capacity is reduced and the residence time of the filtrate 10 is shortened, the solid matter 9a is fixed to the inner surface of the settling tank 5, and a sampling line is provided. It may cause problems such as clogging. There is no particular upper limit to the inclination angle of the bottom 14 from the horizontal plane, but it is preferably 60 degrees or less from the viewpoint of securing the volume of the settling tank 5.

When the shape of the tank body 13 of the settling tank 5 is cylindrical, the shape of the bottom 14 can have a cone shape (conical) or a mortar shape. Due to such a shape, the bottommost portion is arranged in the central portion of the bottom portion 14, and the solid matter 9a settled in the central portion of the bottom portion 14 is uniformly aggregated, and the solid matter 9a can be bottomed out from the central portion of the bottom portion 14. It is easily possible.

By arranging the filtrate receiving inlet 15 in the gas phase portion of the tank body 13, it is possible to suppress blockage due to the solid substance 9a. Specifically, the filtrate receiving inlet 15 is provided at an arbitrary position on the upper end portion of the tank body 13 or the ceiling portion, but when the tank body 13 does not have a ceiling portion, the opening of the tank body 13 is provided. It corresponds to the inlet 15 for receiving the filtrate. It is appropriate to set the upper limit of acceptance of the filtrate 10 below the inlet 15 for receiving the filtrate.

The filtrate receiving inlet 15 is connected to the filtrate supply means 20 for transferring the filtrate 10 from the upstream side such as the filter 3 or the receiver tank 4. The filtrate supply means 20 includes piping and a fluid transfer device including a vacuum pump, a metering pump, a line pump, and other known pumps. In this example, the filtrate 10 is drawn from the filter 3 by a vacuum pump (VP) provided in the receiver tank 4 for vacuum filtration, and the filtrate 10 stored in the receiver tank 4 is appropriately passed through a pipe. It is transferred to the settling tank 5. Therefore, substantially, the vacuum pump (VP) provided in the receiver tank 4 functions as a fluid transfer device. In the present invention, even when the downstream end of the pipe of the filtrate supply means 20 is arranged in the opening of the tank body 13 or vertically above the opening, the filtrate supply means 20 and the filtrate receiving inlet It is interpreted that 15 is connected.

The supernatant extraction outlet 16 is provided at an arbitrary position in the tank body 13 between the upper limit of receiving the filtrate 10 and the upper end portion of the bottom portion 14 (the boundary between the tank body 13 and the bottom portion 14). The supernatant extraction outlet 16 is connected to the supernatant extraction means 21.

Inside the tank body 13, the downstream end (upper end) of the in-tank pipe 18 is connected to the supernatant extraction outlet 16. The upstream end (lower end) of the in-tank pipe 18 is arranged at the horizontal intermediate portion and the height intermediate portion of the bottom portion 14. That is, by arranging the lower end opening of the in-tank pipe 18 at the relevant position in the bottom portion 14, the supernatant can be recovered at once from the bottom, and the solid substance 9a deposited on the wall surface after the filtrate 10 is settled and separated. The supernatant can be recovered by avoiding. Specifically, the arrangement of the in-tank pipe 18 is appropriately set according to the shape of the bottom portion 14 and the amount of solid matter 9a generated by one treatment. The in-tank pipe 18 communicates between the supernatant extraction outlet 16 and the horizontal intermediate portion and the height intermediate portion of the bottom portion 14, and only the supernatant 11 is extracted to the outside of the system by the supernatant extraction means 21. It is possible. As will be described later, depending on the type of the non-contact level sensor, the in-tank pipe 18 may be used in the cross section of the tank body 13 between the supernatant extraction outlet 16 and the upper end of the bottom portion 14. , The non-contact level sensor 19 is arranged at a position that does not interfere with the sensing range.

By providing the outlet 17 for removing the bottom of the solid material at the bottom of the bottom portion 14, it is possible to remove the bottom of the solid material 9a to the maximum extent. When the bottom portion 14 has a cone-shaped (conical) or mortar-shaped shape, the solid material bottom-extracting outlet 17 is provided at the radial center portion of the bottom portion 14. The solid material bottoming outlet 17 is connected to the solid material bottoming means 12. After extracting the supernatant 11, the solid material 9a precipitated by the sedimentation separation of the filtrate 10 is repeated in the cooling crystal tank 2 or the concentration tank 1 via the solid material bottoming outlet 17 and the solid material bottoming means 12. Is done.

The supernatant extraction means 21 and the solid material bottom extraction means 12 are also composed of piping and a fluid transfer device including a vacuum pump, a metering pump, a line pump, and other known pumps, similarly to the filtrate supply means 20. Will be done.

In the present invention, the fluid transfer device constituting the supernatant extraction means 21 or the solid material bottom extraction means 12 can be appropriately selected depending on the object to be conveyed, the transfer height, and the like, and in particular, the metering pump 23 is used. Is preferable. The metering pump 23 includes a gear pump, a bellows pump which is a positive displacement pump using a bellows diaphragm, a plunger pump which is a positive displacement pump which reciprocates a plunger to push out liquid from a suction side to a discharge side, and quantifies in proportion to the number of rotations. A hose pump or the like having a property can be used. By applying the metering pump, the flow rate can be kept constant even if the flow rate changes slightly depending on the particle size, water content, etc. of the precipitated solid substance 9a.

The settling tank 5 according to an example of the embodiment of the present invention further includes a non-contact level sensor 19 and a timer 22.

The non-contact level sensor 19 can be selected from an ultrasonic level sensor, a radio wave level sensor, and a laser level sensor. These non-contact level sensors 19 determine the level of the filtrate in the settling tank 5 by measuring the time when the ultrasonic wave, the radio wave, or the laser is reflected from the liquid surface and returns. Since it can be measured in a non-contact manner, it does not depend on the type of liquid and is resistant to corrosion due to filtrate or the like.

However, since the ultrasonic level sensor and the radio wave level sensor have a relatively large spot diameter, they are easily affected by the shape of the inner surface of the settling tank 5 and obstacles. Therefore, when an ultrasonic level sensor or a radio wave level sensor is used as the non-contact level sensor 19, the non-contact level sensor 19 is the maximum in the settling tank 5 that can be sensed in the tank. It is necessary to arrange the in-tank pipe 18 so as to avoid the dead zone provided in the upper part.

Specifically, of the in-tank pipe 18, the portion arranged above the upper end portion of the bottom portion 14 is arranged along the inner peripheral surface of the tank main body 13, and the portion arranged on the bottom portion 14 is arranged. , It is preferable to arrange it in the vicinity of the surface of the precipitated solid substance 9a. In this case, the non-contact level sensor 19 is arranged at a position radially off the center of the ceiling or opening of the settling tank 5, and the in-tank pipe 18 is in the sensing range of the non-contact level sensor 19. It is preferable not to enter. The portion of the in-tank pipe 18 arranged at the bottom 14 is less likely to fall within the sensing range of the non-contact level sensor 19 as it approaches the settled solid material 9a, but from the settled solid material 9a. The farther away, the less likely it is to be buried in the precipitated solid 9a. Therefore, the portion of the in-tank pipe 18 arranged at the bottom 14 does not interfere with the range sensed by the non-contact level sensor 19, and is at a position where it can be prevented from being buried in the settled solid 9a without a gap. Is placed in.

On the other hand, when a laser level sensor is used as the non-contact level sensor 19, since the spot diameter of the laser level sensor is small, restrictions on the arrangement of the in-tank pipe 18 and the non-contact level sensor 19 are relaxed. However, its application may be limited due to its high cost including management cost.

The level sensor also includes a contact type level sensor such as a float type level sensor that uses a float and an electrode type level sensor that applies a voltage between electrodes to detect the current flow depending on the presence or absence of liquid. The effect of sticking solids in the filtrate occurs. For example, in an electrode type level sensor, a solid matter settled on the tip of an electrode rod may be stuck and short-circuited, so that accurate detection may not be possible. Therefore, in the present invention, it is practically difficult to use these contact level sensors.

The sensing of the level of the filtrate 10 by the non-contact level sensor 19 extends upward from the upper end of the bottom 14 of the settling tank 5. This is because, in one example of the embodiment of the present invention, the bottom portion is inclined so as to have an inclination angle of 40 degrees or more from the horizontal plane, so that the level of the filtrate 10 is lower than the height position of the upper end portion of the bottom portion 14. This is because proper sensing cannot be performed. In particular, when the shape of the bottom portion 14 has a cone-shaped (conical) or mortar-shaped shape, if the bottom portion 14 is within the detection distance and detection angle of the non-contact level sensor 19, the non-contact level sensor 19 erroneously indicates. Is likely to do. Therefore, the non-contact level sensor 19 is set to end the sensing at the same time when the level of the filtrate 10 reaches the height of the upper end portion of the bottom portion 14, or the timer 22 described below is activated. Therefore, it is desirable to shift to process control using the timer 22.

In an example of the embodiment of the present invention, a timer 22 is installed in addition to the non-contact level sensor 19. In this example, instead of measuring the level of the filtrate 10 at the bottom 14, a timer 22 is used to control the extraction time of the supernatant 11 existing in the bottom 14 and the bottom extraction time of the solid material 9a.

That is, the timer 22 is located at a position where the level of the filtrate 10 is slightly above the height of the region of the bottom 14 where the precipitated solid 9a is present, in other words, the upstream end of the in-tank pipe 18. The time until the opening of the lower end portion) reaches the existing height position is controlled by time, and the operation of the pump constituting the supernatant extraction means 21 is stopped before idling. As described above, the timer 22 is set when the level of the filtrate 10 reaches a predetermined position, for example, when the level of the filtrate 10 reaches the upper end of the bottom 14 by sensing by the non-contact level sensor 19. When the time measurement is started and a predetermined time elapses when the level of the filtrate 10 reaches the lower end of the in-tank pipe 18 (immediately before), the operation of the supernatant extraction means 21 is stopped.

Next, the timer 22 activates the solid matter bottoming means 12 to start bottoming out of the solid matter 9a, and after a predetermined time elapses after the start of bottoming out of the solid matter 9a, that is, the solid matter 9a is sufficient. However, the operation of the solid material bottoming means 12 is stopped before the pump constituting the solid material bottoming means 12 overheats due to idling.

Regarding the operating time of the timer, the time required to extract the precipitated solid substance 9a and the supernatant 11 is examined according to the configuration of the fluid transfer device constituting the supernatant extraction means 21 or the solid substance bottom extraction means 12, respectively. It will be decided as appropriate. In particular, when a metering pump is used as the fluid transfer device, the lower end of the in-tank pipe 18 starts from the time when the level of the filtrate 10 is at a predetermined position (upper end of the bottom 14) as the capacity of the filtrate 10. Since the capacity up to and the capacity from the lower end of the in-tank pipe 18 to the bottom of the bottom 14 can be obtained by calculation, a preliminary test for determining the operating time of the timer is unnecessary.

The non-contact level sensor 19 and the timer 22 have a switch mechanism for controlling the operation of the filtrate supply means 20, the supernatant extraction means 21, and the solid matter bottom extraction means 12 by the non-contact level sensor 19 and the timer 22. Can be used. Alternatively, a computer, a control device, or the like is separately provided, and the non-contact level sensor 19, the timer 22, the filtrate supply means 20, the supernatant extraction means 21, and the solid material bottom removal means 12 are operated as a whole through these. Can also be managed and controlled.

The settling tank of the present invention is controlled as follows.

First, the filtrate supply means 20 receives the filtrate 10, and when the non-contact level sensor 19 detects that the level of the filtrate 10 has reached the upper limit of the filtrate acceptance, the filtrate supply means 20 is activated. Stop and finish accepting the filtrate 10. The non-contact level sensor 19 is arranged so as to be able to detect at least the level of the filtrate 10 in the tank body 13. Depending on the type of non-contact level sensor 19, if there is a dead zone in the sensing range, at least the height range between the lowest level of the dead zone present at the top of the tank body 13 and the top of the bottom 14. Is arranged so that it can be sensed. In this case, the upper limit of the filtrate acceptance is set at a position below the lowest level of the dead zone, preferably slightly below the lowest level of the dead zone.

After that, the filtrate 10 is settled and separated in the settling tank 5 with a predetermined residence time, and the solid 9a is settled.

After the lapse of a predetermined residence time, the supernatant extraction means 21 starts extracting the supernatant 11 generated by sedimentation separation, and the non-contact level sensor 19 is at least the lower limit of the height range with respect to its sensing, that is, the bottom 14. Continue sensing the level of filtrate 10 to the top of the.

Simultaneously with the stop of sensing by the non-contact level sensor 19, or when the level of the filtrate 10 reaches a predetermined position, the timer 22 starts, the supernatant 11 is continuously extracted, and the level of the filtrate 10 is in the tank. After a predetermined time elapses when the lower end of the pipe 18 is reached (immediately before), the operation of the supernatant extraction means 21 is stopped, and the extraction of the supernatant 11 is completed.

Substantially at the same time as the stoppage of the extraction of the supernatant, the solid matter bottoming out means 12 operates, and the solid matter bottoming out means 12 continues the bottoming out of the solid matter 9a for a predetermined time until the timer 22 is stopped.

In this way, the solid matter 9a precipitated and concentrated in the settling tank 5 is repeated in a predetermined place in the previous step, that is, the cooling crystal tank 2 or the concentration tank 1 in a slurry state by the solid matter bottoming means 12. .. After the total amount of the solid material 9a has been removed, the timer 22 is stopped to stop the operation of the solid material bottoming means 12, and the filtrate 10 is separated by sedimentation and the supernatant 11 and the solid material 9a are separated. Complete one cycle of extraction.

In the present invention, in order to obtain the precipitation of fine solid matter 9a such as crude nickel sulfate in the settling tank 5, it is important to settle the filtrate 10 containing the fine solid matter for a predetermined time. In order to settle the fine solid substance 9a from the filtrate 10 sent to the settling tank 5 and sufficiently obtain the precipitate of the solid substance 9a, the settling after stopping the charging of the filtrate 10 into the settling tank 5. The residence time in the tank 5 is preferably 15 minutes or more, and in order to reliably precipitate 90% or more of the solid matter 9a, it is preferable to secure the residence time in the sedimentation tank 5 for 20 minutes or more.

The upper limit of the residence time is not limited as long as it is 15 minutes or more, preferably 20 minutes or more, but the longer the residence time, the lower the amount of the treatment liquid per hour. Therefore, a large settling tank 5 is required to hold the filtrate 10 sent out from the filter 3. Considering these circumstances, it is desirable that the residence time is 50 minutes or less, preferably 40 minutes or less.

Further, in the present invention, the acceptance of the filtrate 10 into the settling tank 5 and the sedimentation and bottom removal of the solid material 9a are clearly distinguished, that is, the charging of the filtrate 10 into the settling tank 5 is stopped. After that, it is important to settle and bottom out the solid 9a. In order to effectively carry out the present invention, the filtrate 10 filtered by the filter 3 may be intermittently sent to the settling tank 5 via the receiver tank 4. As a result, in the settling tank 5, the filtrate 10 is received, the solid matter 9a is settled, and the solid matter 9a is settled, while the filtration is continuously performed by the filter 3, that is, the amount of liquid flowing through the filter 3 is kept large. It is possible to distinguish the bottom in terms of time.

Further, in the present invention, the settling tank 5 has a function of providing a waiting time for only settling and separating the filtrate 10 after receiving the filtrate 10 or before removing the bottom of the solid 9a and extracting the supernatant 11. Have. As long as such a function of the settling tank 5 can be ensured, it is sufficient to install one settling tank 5. However, in order to secure a sufficient residence time, it is effective to install two or more sedimentation tanks 5. For example, as shown in FIG. 1, two settling tanks 5 are provided, and as the first step, one of them accepts the filtrate 10 and the other one setstles and bottoms out the solid material 9a. In addition, the supernatant 11 was extracted, and as a second step, one unit that had received the filtrate 10 was switched to the precipitation and bottom extraction of the solid material 9a, and the extraction of the supernatant 11 to perform these operations. In another unit that was performing the precipitation and bottom removal of the solid material 9a and the extraction of the supernatant 11, the filtrate 10 was accepted instead of these, and the first step and the second step were performed. It is preferable to perform each of these alternately. This makes it possible to provide a sufficient waiting time for only the sedimentation separation of the filtrate 10 after receiving the filtrate 10 or before the bottom removal of the solid 9a and the extraction of the supernatant 11. A temporal distinction between settling and bottoming out is made. In order to distribute the liquid to two or more settling tanks 5, a three-way valve may be arranged upstream of the settling tank 5, but the present invention is not limited to this mode.

A sufficient residence time of the filtrate 10 can be secured, and the acceptance of the filtrate 10 and the sedimentation and bottom removal of the solid substance 9a and the extraction of the supernatant 11 are clearly distinguished, and the sedimentation of the solid substance 9a is made. The receiver tank 4 can be omitted as long as the bottoming is performed separately in time. For example, if the total of the residence time of the filtrate 10 and the time for bottoming out the solid 9a and extracting the supernatant 11 is shorter than the receiving time of the filtrate 10, even if the receiver tank 4 is omitted, two units are used. The filtrate 10 can be continuously delivered from the filter 3 while switching the settling tank 5 of the above.

In the step of bottoming out the solid matter 9a from the settling tank 5 and extracting the supernatant 11, the sedimentation of the solid matter 9a is bottomed out from the lower part of the settling tank 5 by the metering pump 23 provided in the solid matter bottoming out means 12. Then, the process is repeated in the cooling crystal tank 2 or the concentration tank 1 (cooling crystal tank 2 in the example of FIG. 1), and the supernatant 11 is discharged from the upper part of the settling tank 5. Since the supernatant 11 contains a large amount of sulfuric acid, it can be added to the electrolytic solution and used for adjusting the acid concentration.

When the filtrate 10 from the filter 3 contains particles of a solid substance 9a having a large particle size, the particles may settle in the receiver tank 4 before reaching the settling tank 5. Therefore, it is preferable to send almost all the particles of the solid substance 9a to the settling tank 5 by appropriately adjusting the residence time of the filtrate 10 in the receiver tank 4.

Hereinafter, the present invention will be described in more detail by way of examples. In the examples, the decopperating final liquid generated in the electrolytic refining of copper is treated as the liquid to be treated, and the crude nickel sulfate precipitated and recovered in the denickeling step from the decoppering final liquid is treated as a solid substance. It is not limited to the embodiment of.

(Example 1)
Concentration tank 1, cooling crystal tank 2, filter 3, receiver tank 4, and two settling tanks 5 (all have a volume of 800 L, an inner diameter of 1 m, and a height of the tank body 13 are 0, as shown in FIGS. 1 and 2. A crude nickel sulfate recovery device composed of 9.9 m and a bottom 14 height of 0.5 m) was used.

The settling tank 5 includes a tank body 13 and a bottom portion 14, and the bottom portion 14 has a cone-shaped shape and is located at the radial center portion of the bottom portion 14 so that the inclination angle from the horizontal plane is 45 degrees. A settling tank was used, which was inclined toward the bottom.

A filtrate receiving inlet 15 is provided in a part of the ceiling of the tank body 13, a supernatant extraction outlet 16 is provided in the upper part of the side wall of the tank body 13, and a solid material bottom extraction outlet 17 is provided in the bottom of the bottom 14. Provided. The filtrate supply means 20 for supplying the filtrate 10 from the receiver tank 4 to the filtrate receiving inlet 15, and the supernatant extraction means 21 for extracting the supernatant 11 from the inside of the tank to the supernatant extraction outlet 16. The solid material bottom removing means 12 for removing the bottom of the solid material 9a from the tank and returning it to the cooling crystal tank 2 was connected to the solid material bottoming out outlet 17. The filtrate supply means 20, the supernatant extraction means 21, and the solid matter bottom extraction means 12 were all configured by piping and a metering pump.

The downstream end (upper end) of the in-tank pipe 18 was connected to the supernatant extraction outlet 16. From the upper end to the middle of the in-tank pipe 18, the tank main body 13 (cylindrical portion) and the bottom portion 14 were arranged in the vicinity of the inner peripheral surface along the inner peripheral surface. The in-tank pipe 18 is bent at an intermediate portion, and the upstream end (lower end) of the in-tank pipe 18 is projected from the vicinity of the inner peripheral surface of the tank body 13 toward the radial center, and the height of the bottom 14 is increased. An opening at the lower end of the in-tank pipe 18 was opened at the center in the radial direction at the middle portion in the radial direction.

Non-contact level sensor 19 (manufactured by Yokogawa Electric Co., Ltd.), which is an ultrasonic level sensor, is located on the ceiling of the tank body 13 away from the radial center and on the opposite side of the tank pipe 18 in the radial direction. , SUN61) was installed.

The crude nickel sulfate recovery device incorporating the settling tank 5 configured as described above was operated as follows.

First, the liquid to be treated 6 which is the final liquid for removing copper of 0 g / L of copper and 30 g / L to 40 g / L of nickel was supplied to the concentration tank 1. The liquid temperature of the concentrating tank 1 was maintained in the range of 150 ° C. to 170 ° C. by Joule heat of the graphite electrode.

The concentrated liquid 7 was discharged from the concentrated tank 1 to the cooled crystal tank 2 by overflow, and was forcibly cooled so that the liquid temperature in the cooled crystal tank 2 was 60 ° C. or lower. This cooling was performed by flowing industrial water into a serpentine tube provided in the cooling crystal tank 2.

The generated slurry 8 containing crude nickel sulfate is continuously filtered by a vacuum filter so as to keep the liquid level of the cooling crystal tank 2 constant by using a vacuum pump (VP) provided in the receiver tank 4. It was supplied to the vessel 3 and the solid substance 9 which was crude nickel sulfate was recovered. The filtrate 10 containing the residual nickel sulfate that leaked through the filtration was supplied to the receiver tank 4.

The filtrate 10 is operated from the filtrate supply means 20 and the ultrasonic level sensor, which is a non-contact level sensor 19, and the filtrate 10 is sent from the receiver tank 4 to one of the settling tanks 5 via the filtrate supply means 20. When the non-contact level sensor 19 detects that the level of the filtrate 10 has reached the upper limit of acceptance after starting the feeding, the operation of the filtrate supply means 20 is stopped and the acceptance of the filtrate 10 is stopped.

The filtrate 10 was settled and separated with the residence time of the filtrate 10 in the settling tank 5 being 40 minutes, and the solid substance 9a, which was residual crude nickel sulfate, was settled on the bottom 14. In this example, another one of the two settling tanks 5 was not operated, and the filtrate 10 was discharged from the receiver tank 4 to the outside of the system until the next filtrate 10 was received.

The supernatant extraction means 21 and the non-contact level sensor 19 are operated, and the non-contact level sensor 19 senses the level of the filtrate 10 while extracting the supernatant generated by the sediment separation by the supernatant extraction means 21. When the level of the filtrate 10 reached the top of the bottom 14, the timer 22 was activated and at the same time the sensing was stopped.

When 120 seconds have passed since the timer 22 was operated, the supernatant extraction means 21 was stopped, and at the same time, the solid material bottom extraction means 12 was operated to return the solid material 9a to the cooling crystal tank 2. The timer 22 stopped the operation of the solid material bottoming means 12 180 seconds after the operation of the solid material bottoming means 12. The supernatant was sent to an electrolytic cell for use as a part of the electrolytic solution.

The amount of liquid discharged from the receiver tank 4 to the outside of the system was almost the same as the amount of liquid sent to the settling tank 5. That is, in this example, the treatment rate of the filtrate 10 in the settling tank 5 was substantially 50%. The above test operation was carried out for 3 months, and the monthly recovery rate of crude nickel sulfate was determined. As a result, the recovery rate of crude nickel sulfate was 83% on average.

(Example 2)
Unlike Example 1, two settling tanks 5 were used. The receiver tank 4 supplies one of the settling tanks 5 (first tank) until the filtrate 10 in the settling tank 5 reaches the upper limit of acceptance, and after the supply is stopped, the filtrate 10 is supplied to the settling tank 5. It was switched to another one (second tank) of the above, and the filtrate 10 was supplied in the same manner. While the filtrate 10 is being supplied to the second tank, the residence time of the filtrate 10 in the first tank is set to 40 minutes, and then the supernatant 11 is extracted from the first tank and the solid substance (residual crude nickel sulfate) 9a. The bottom was removed. After the bottoming was completed, the supply of the filtrate 10 to the first tank was restarted. While the filtrate 10 was being supplied to the first tank, the supernatant 11 was extracted and the solid 9a was bottomed out after the residence time of the filtrate 10 was 40 minutes in the second tank as well. After the bottoming was completed, the supply of the filtrate 10 to the second tank was restarted. The control of the two settling tanks 5 was performed in the same manner as in Example 1. These steps were repeated in sequence to operate the recovery of crude nickel sulfate.

When the amount of liquid in the receiver tank 4 was small, the liquid was sent from the receiver tank 4 to the settling tank 5 after the amount of liquid reached a certain level or higher.

In this example, the entire amount of the filtrate 10 could be treated in the settling tank 5, and the treatment rate in the settling tank 5 was substantially 100%. The above test operation was carried out for 3 months, and the monthly recovery rate of crude nickel sulfate was determined. As a result, the recovery rate of crude nickel sulfate was 87% on average.

(Comparative Example 1)
The test operation was carried out for 3 months in the same manner as in Example 1 except that the filtrate 10 filtered by the filter 3 which is a vacuum filter and stored in the receiver tank 4 was discharged as it was without using the settling tank 5. The monthly recovery rate of crude nickel sulfate was calculated. As a result, the recovery rate of crude nickel sulfate was 80%.

(Comparative Example 2)
Instead of the ultrasonic level sensor (non-contact level sensor 19) and the timer, an electrode type level sensor which is a contact type level sensor is used, and the tip of the electrode rod of the electrode type level sensor is the lower end of the tank pipe 18. The test operation was carried out in the same manner as in Example 1 except that the electrode type level sensor was installed so as to be arranged at the same height as the part.

When the process from receiving the filtrate 10 to completing the bottom removal of the solid material 9a is repeated for several days, the lower limit of the extraction of the supernatant 11 by the electrode type level sensor cannot be detected, and the pump of the supernatant extraction means 21 idles for a long time. A situation has occurred. When the settling tank 5 was opened and the inside was checked, residual nickel sulfate was found to be stuck to the electrode rod and between them. When crude nickel sulfate was removed from the electrode rod, discoloration and cracks were observed in the electrode rod. When the filtrate 10 was received, the flow of the filtrate became poor around the electrode rod, and residual nickel crude sulfate that had settled around the electrode rod was deposited, and nickel sulfate was newly deposited, resulting in a short circuit. Is thought to be the cause.

(Discussion)
The recovery rate of crude nickel sulfate is determined by dividing the amount of nickel recovered from the filter 3 by the amount of nickel supplied to the concentrating tank 1 (the total amount of nickel contained in the liquid to be treated 6). In Example 1 in which the settling tank 5 was used, the residual nickel crude sulfate that had not been filtered was recovered, and the recovery rate of the crude nickel sulfate was improved by 3%, as opposed to Comparative Example 1 in which the settling tank 5 was not used. It will be. Further, in Example 2 in which the entire amount of the filtrate 10 was treated in the settling tank 5, more residual nickel sulfate leaked from the filtration was recovered, and the recovery rate of the crude nickel sulfate was improved by 7%. .. Since these improvements in the recovery rate are due to the recovery of filtration leaks, the recovery rate can be stably improved regardless of the amount of nickel sulfate remaining dissolved in the supernatant 11.

1 Concentration tank 2 Cooling crystal tank 3 Filter 4 Receiver tank 5 Sedimentation tank 6 Treatment liquid (copper removal final liquid)
7 Concentrate 8 Slurry 9 Solid (crude nickel sulfate)
10 Filtrate 11 Supernatant 12 Solid material bottom punching means 13 Tank body (cylindrical part side)
14 Bottom 15 Inlet for receiving filtrate 16 Outlet for extracting supernatant 17 Outlet for extracting solid bottom 18 Piping in tank 19 Non-contact level sensor (ultrasonic level sensor)
20 Filtrate supply means 21 Clearance extraction means 22 Timer 23 Metering pump

Claims (8)

The tank body, the bottom, the inlet for receiving the filtrate, the outlet for extracting the supernatant, the outlet for removing the bottom of the solid matter provided at the bottom, the pipe in the tank connected to the outlet for extracting the supernatant, and the filter. A means for supplying the filtrate through the liquid receiving inlet, a means for extracting the supernatant generated by the sedimentation separation of the filtrate via the in-tank pipe and the outlet for extracting the supernatant, and the means for removing the bottom of the solid material. A settling tank provided with a means for bottoming out the solid matter settled by the settling separation of the filtrate via the outlet for.
The settling tank further comprises a non-contact level sensor and a timer arranged so as to be able to sense the level of the filtrate in the settling tank.
The bottom portion is tilted downward toward the outlet for removing the bottom of the solid material.
The outlet for removing the bottom of the solid material is arranged at the bottom of the bottom.
The in-tank pipe extends from the supernatant extraction outlet to the horizontal intermediate portion and the height intermediate portion of the bottom portion, and has an opening at the lower end portion.
The non-contact level sensor operates a means for supplying the filtrate until the level of the filtrate reaches the upper limit of accepting the filtrate in the tank, and the filtrate is settled and separated, and the supernatant is separated. After the actuation of the means for extracting the supernatant, the level of the supernatant is detected, and
The timer is activated when the level of the supernatant reaches the upper end of the bottom portion, and is a means for extracting the supernatant when a predetermined time elapses before the level of the supernatant reaches the opening of the pipe in the tank. The operation is stopped, and the means for bottoming out the solid matter is operated, and after a lapse of a predetermined time, the means for bottoming out the solid matter is stopped.
Sedimentation tank. The settling tank according to claim 1, wherein the non-contact level sensor is selected from an ultrasonic level sensor, a radio wave level sensor, and a laser level sensor. The sedimentation tank according to claim 1 or 2, wherein the bottom portion has a cone-shaped or mortar-shaped shape. The sedimentation tank according to any one of claims 1 to 3, wherein the bottom portion has an inclination angle of 40 degrees or more from a horizontal plane. The in-tank pipe is arranged between the supernatant extraction outlet and the upper end of the bottom at a position in the cross section of the tank body that does not interfere with the range sensed by the non-contact level sensor. The settling tank according to any one of claims 1 to 4. Using the settling tank according to any one of claims 1 to 5,
A step of receiving the filtrate by the means for supplying the filtrate and stopping the acceptance of the filtrate when the non-contact level sensor detects the upper limit of the filtrate acceptance in the tank.
A step of precipitating and separating the filtrate in the settling tank to settle the solid matter on the bottom.
When the supernatant is started to be extracted by the means for extracting the supernatant, the non-contact level sensor detects the level of the supernatant, and the timer reaches the upper end of the bottom. A step of operating and stopping the extraction of the supernatant when a predetermined time elapses before the level of the supernatant reaches the opening of the pipe in the tank.
At the same time as the extraction of the supernatant is stopped, the bottoming out of the solid matter is started by means for bottoming out the solid matter, and after a predetermined time has elapsed after the start of bottoming out of the solid matter, the bottoming out of the solid matter is performed. The process of stopping,
To prepare
Control method of settling tank. A concentration process in which the liquid to be treated is heated and concentrated to obtain a concentrated liquid,
A cooling step of cooling the concentrate to precipitate a solid substance and obtaining a slurry containing the solid substance.
A filtration step of filtering the slurry to recover the solid matter,
The filtrate containing the solid matter obtained in the filtration step and leaked from filtration is put into a settling tank, and the solid matter in the filtrate is settled at the bottom of the settling tank and settled at the bottom of the settling tank. The process of extracting the solidified material and repeating it before the cooling process,
Equipped with
In the step using the settling tank, the control method for the settling tank according to claim 6 is used.
Manufacturing method for solids. Two or more of the settling tanks are provided, and the filtrate is charged into any one of the settling tanks, and the solid matter is settled and / or extracted in at least one of the settling tanks. The method for producing a solid substance according to claim 7, wherein the above is performed at the same time.

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