JP6848497B2 - Slurry flow method and slurry flow device - Google Patents

Description

The present invention relates to a slurry flow method and a slurry flow device. More specifically, the present invention relates to a slurry flow method and a slurry flow device, which can be particularly preferably applied to the flow of crude zinc oxide slurry generated in a production plant for obtaining zinc oxide ore from zinc-containing ore.

Generally, in industrial fields dealing with raw water or treated water such as water treatment using an ion exchange membrane, treatment of boiler water and cooling water, treatment of exhaust gas washing water, silica and calcium dissolved in raw water or treated water are the cause. As a result, scale may occur on the surface of the ion exchange film, the heat transfer surface of the boiler, the inside of the pipe, and the inside of the heat exchanger. When this scale is generated, it causes various problems such as a significant decrease in the efficiency of ion exchange and heat exchange, and a blockage of piping that makes it extremely difficult to flow.

This scale generation problem also occurs without exception during the treatment of the crude zinc oxide slurry obtained by wet-cleaning the crude zinc oxide dust generated by melting, roasting, heating, or drying in an industrial furnace. .. For example, the above treatment in a manufacturing plant for obtaining zinc oxide ore from zinc-containing ore corresponds to this. The generation of such scale has been a factor of lowering the operating rate of the manufacturing plant and the like, for example, the piping for flowing the slurry is blocked and the operation is obliged to be interrupted.

As a measure against scale in a general water treatment device, a water treatment device (see Patent Document 1) equipped with an addition device or the like for adding a scale dispersant to the raw water to be treated, or a divalent ion such as Ca ion is used. A water treatment system (see Patent Document 2) and the like having a scale inhibitor supply unit that supplies a scale inhibitor to the mixed water containing the mixture are disclosed. Similarly, in the above-mentioned zinc oxide ore manufacturing plant, as a measure against scale, measures have been taken to supply various scale inhibitors according to the scale component to be treated to the storage tank of the slurry.

However, the effect of the above scale measures is not always sufficient, especially in a pipe having a narrow inner diameter for flowing slurry from a large storage tank. Further, since it is difficult to clean and remove such a pipe having a narrow inner diameter after the scale is generated, a means capable of more effectively preventing the adhesion of the scale has been required.

Japanese Unexamined Patent Publication No. 2012-183472 Japanese Unexamined Patent Publication No. 2015-128754

The present invention has been devised in view of the above problems, and can suppress scale adhesion more effectively than conventional means in a narrow pipe for flowing slurry from a large storage tank. It is an object of the present invention to provide a means for flowing a slurry.

In the extraction pipe connected to the side surface of the storage tank, the present inventors directly supply the scale inhibitor into the extraction pipe at a position within a specific distance range from the connection end to the storage tank. We have found that the amount of scale adhering to the inside can be suppressed extremely effectively, and have completed the present invention. Specifically, the present invention provides the following.

(1) A method for flowing a slurry stored in a storage tank having an inner diameter of 1000 mm or more through a sampling pipe having an inner diameter of 200 mm or less connected to a side surface of the storage tank. A method for flowing a slurry, which is directly supplied into the extraction pipe from a scale inhibitor addition port installed at a position of 0 mm or more and 100 mm or less from the connection end of the extraction pipe on the storage tank side.

In the invention of (1), as a measure against scale of the extraction pipe, the scale inhibitor is directly supplied to a predetermined position of the extraction pipe for flowing the slurry without passing through the storage tank. According to this, the effect of suppressing the adhesion of scale in the pipe is remarkably improved as compared with the case of the conventional method in which the same amount of the scale inhibitor is supplied to the storage tank. This is because, in the case of the conventional method, many parts of the anti-scale agent acted in the storage tank having a long residence time, whereas according to the invention of (1), the adhesion of scale is fatal. This is because almost all anti-scale agents can be effectively acted on in a narrow pipe, which tends to cause a problem.

(2) The slurry is a crude zinc oxide slurry in which crude zinc oxide dust having a zinc content of 30% by weight or more and 70% by weight or less is suspended at a slurry concentration of 1 g / L or more and 50 g / L or less. The anti-scale agent is an anti-scale agent containing at least one of a chelating agent, a phosphonic acid, and a maleic acid-based polymer, and is 1 μL / L or more and 30 μL / L or less with respect to the crude zinc oxide slurry. The method for flowing a slurry according to (1), wherein the supply amount of the scale inhibitor is adjusted so as to have a concentration.

According to the invention of (2), for example, the invention of (1) is particularly preferable as a measure against scale of piping generated due to a crude zinc oxide slurry having general properties generated in a zinc oxide ore production plant. Can be applied at.

(3) The method for flowing a slurry according to (1) or (2), wherein the scale inhibitor is not supplied to the storage tank but is supplied only to the inside of the sampling pipe.

According to the invention of (3), the scale inhibitor is extracted and supplied only to the inside of the pipe. According to this, in the implementation of the slurry flow method according to (1) or (2), a sufficient effect of suppressing scale adhesion can be obtained with the minimum necessary supply amount of the scale inhibitor, and (1). ) Or (2), the production cost in the production of zinc oxide ore or the like, which is carried out by using the slurry flow method according to (2), can be suppressed.

(4) The storage tank is a tank for storing crude zinc oxide slurry generated in a production plant for obtaining zinc oxide ore from zinc-containing ore, and is a flow of the slurry according to any one of (1) to (3). Method.

According to the invention of (4), the above effect of the slurry flow method of any one of (1) to (3) is enjoyed, which contributes to the improvement of the operating rate and the economic efficiency of the zinc oxide ore manufacturing plant. can do.

(5) A slurry flow device for flowing slurry, the storage tank having an inner diameter of 1000 mm or more and a sampling pipe having an inner diameter of 200 mm or less connected to the side surface of the storage tank. A slurry flow device in which a scale inhibitor addition port is installed at a position of 0 mm or more and 100 mm or less from the connection end on the tank side.

According to the invention of (5), the scale inhibitor supplied as a measure against scale of the pipe can be directly supplied to a predetermined position of the sampling pipe through which the slurry is sent without passing through the storage tank. According to this, the effect of suppressing the adhesion of scale in the pipe is remarkably improved as compared with the case of the conventional method in which the same amount of the scale inhibitor is supplied to the storage tank. This is because, in the case of the device having the conventional configuration, many parts of the anti-scale agent act in the storage tank having a long residence time, whereas according to the invention of (5), the scale adheres. This is because almost all anti-scale agents can be effectively acted only in a narrow pipe, which tends to be a fatal problem.

(6) The slurry flow device according to (5), further comprising a flow pump whose suction side is connected to the extraction pipe and a flow pipe having an inner diameter of 200 mm or less connected to the discharge side of the flow pump. ..

According to the invention of (6), since the scale inhibitor is supplied to the suction side of the flow pump, the scale inhibitor is uniformly dispersed in the pipe due to the ejector effect, so that the scale inhibitor is added into the extraction pipe. The effect of the present invention can be enjoyed at a preferable level without performing additional processing such as inserting a thin tube.

(7) The slurry is a crude zinc oxide slurry in which crude zinc oxide dust having a zinc content of 30% by weight or more and 70% by weight or less is suspended at a slurry concentration of 1 g / L or more and 50 g / L or less. 5) Or the slurry flow device according to (6).

According to the invention of (7), for example, the invention of (5) or (6) is used as a measure against scale of piping generated due to a crude zinc oxide slurry having general properties generated in a zinc oxide ore manufacturing plant. Can be applied in a particularly preferred embodiment.

According to the present invention, it is possible to provide a slurry flow means capable of suppressing scale adhesion more effectively than the conventional means in a narrow pipe for flowing the slurry from a large storage tank.

It is a schematic diagram which showed the structure of the slurry flow device of this invention.

Hereinafter, a preferred embodiment of the slurry flow method and the slurry flow device of the present invention will be described. The present invention is widely applicable to various industrial processes including the step of flowing the slurry from the tank for storing the slurry, and particularly in the industrial process including the step of flowing the crude zinc oxide slurry by piping. It can be preferably carried out. Typical examples of an industrial process including a step of flowing a crude zinc oxide slurry through a pipe include a "zinc oxide ore manufacturing process" described in detail below, that is, a reduction roasting step, a wet step, and a drying and heating step. The manufacturing process of zinc oxide ore consisting of In the following, the application of the method or apparatus of the present invention to the production process of zinc oxide ore will be described in detail as an example of a preferred embodiment of the present invention. However, the present invention is not limited to the embodiments described below, and changes can be made without changing the gist of the present invention.

<Zinc oxide ore manufacturing process>
The production process of zinc oxide ore by the Welts method is a reduction roasting process in which zinc-containing ore such as steel dust is reduced and roasted to obtain crude zinc oxide dust, and fluorine and cadmium from crude zinc oxide dust obtained in the reduction roasting step. This is a process in which a wet step of separating and removing zinc oxide to obtain a crude zinc oxide cake and a drying and heating step of drying and heating the crude zinc oxide cake obtained in the wet step to obtain zinc oxide ore (roasted ore) are sequentially performed. INDUSTRIAL APPLICABILITY The present invention can be extremely preferably carried out in such a zinc oxide ore production process as a means for flowing a crude zinc oxide slurry containing DRK exhaust gas dust discharged from a drying and heating step from a storage tank. .. The present invention can be preferably carried out, for example, in a general zinc oxide ore production process in which the amount of zinc oxide ore produced is about 6 t / h or more and 10 t / h or less, and the present invention is not limited to this. It can be implemented in a large-scale manufacturing plant as well.

[Reduction roasting process]
In the reduction roasting step, a process of reducing and roasting a raw material or the like in which steel dust is pelletized together with a reducing material in advance by a rotary kiln for reduction roasting (RRK) is performed. In this step, the raw material pellets are continuously charged into RRK together with limestone and the like. Raw materials derived from steel dust are reduced and roasted in the RRK furnace, and the volatilized metallic zinc is reoxidized in the furnace to become powdery zinc oxide. The powdery zinc oxide is introduced into the dust collector together with the exhaust gas from the RRK, is captured, and is recovered as crude zinc oxide dust.

[Wet process]
In the wet step following the reduction roasting step, water-soluble impurities such as chlorine and fluorine contained in the crude zinc oxide dust obtained in the reduction roasting step are separated and extracted into the treatment liquid, and further solid-liquid separation treatment is performed. A wet treatment is performed in which impurities are removed from the crude zinc oxide dust by a water washing method to obtain a crude zinc oxide cake. More specifically, in a state where halogen-based impurities such as chlorine and fluorine are removed in the treatment liquid, the treatment liquid in which the impurities are distributed is removed from the slurry by solid-liquid separation. As a result, the crude zinc oxide dust becomes a crude zinc oxide cake from which halogen-based impurities have been removed.

[Drying and heating process]
In the drying and heating step, the crude zinc oxide cake obtained in the wet step is put into a rotary kiln (DRK) for drying and heating and calcined to produce a high-grade zinc oxide ore while further reducing the halogen concentration. Perform processing. The water content of the crude zinc oxide cake to be treated in this step is generally 20% by mass or more and 30% by mass or less. The general composition of the crude zinc oxide cake is as follows: zinc is 61% by mass or more and 68% by mass or less, lead is 7% by mass or more and 10% by mass or less, chlorine is 0.3% by mass or more and 0.9% by mass or less. Fluorine is 0.2% by mass or more and 1.5% by mass or less (both are based on the amount of dryness). Such a crude zinc oxide cake is charged into the DRK in the form of a hydrous cake by a quantitative charging device such as a screw feeder. The crude zinc oxide cake charged into the DRK is granulated into pellets on the charging end side inside a rotary kiln having a length of about 30 m, then dried, heated, and fired on the discharging end side.

The DRK is provided with an oil burner on the discharge end side for discharging zinc oxide ore, and is heated by an open flame from the discharge end side. The temperature of the zinc oxide ore burnt discharged from the rotary kiln is continuously measured and monitored by a radiation thermometer. The firing temperature is the temperature of the zinc oxide ore sinter, and is maintained and managed so as to be in the range of 900 ° C. or higher and 1200 ° C. or lower. The firing temperature can be adjusted, for example, by the amount of oil supplied to the oil burner. In the drying and heating step, the size of zinc oxide ore discharged from DRK is generally 1 mm or more and 6 mm or less, and its general composition is 60% by mass or more and 70% by mass or less of zinc and 3% by mass or more of lead. 5% by mass or less, chlorine is 0.5% by mass or more and 1.5% by mass or less, and fluorine is about 0.6% by mass or less (all based on the dry amount).

The charged material such as crude zinc oxide cake charged in the DRK is granulated, dried, heated, and baked in this order in a rotary kiln of about 30 m. Then, dust of the charged material scattered in the process of granulation and drying, oxides and halides volatilized in the process of heating and firing become dust. The dust concentration of the DRK exhaust gas is about 30 g / Nm ³ or more and 40 g / Nm ³ or less. Further, the exhaust gas flow discharged from the DRK is much higher 15000 m ³ / h or less 14000m ³ / h.

[Exhaust gas treatment]
The exhaust gas discharged from the DRK is sucked from the charging end side, finally removed by a wet gas scrubber and a wet electrostatic precipitator, and discharged from the chimney via a blower such as a fan. The slurry flow method and slurry flow device of the present invention provide crude zinc oxide slurry containing exhaust gas dust in the exhaust gas during a series of processes for cleaning the DRK exhaust gas discharged from the drying and heating step. It can be preferably used as a means for flowing from the storage tank.

Here, in the above series of processes related to the cleaning treatment of the DRK exhaust gas, usually, prior to the final cleaning treatment by the wet treatment apparatus, a reserve with washing water is used in the flue immediately after the discharge from the rotary kiln. Cleaning is done. More specifically, in this preliminary cleaning, the present invention can be extremely preferably used as a means for extracting the crude zinc oxide slurry from the storage tank (circulation tank) and flowing it through the extraction pipe.

The above pre-cleaning is installed near the exhaust gas outlet of the rotary kiln, and the cleaning water is poured into the flue that sends the exhaust gas to the next process, and the treated water containing the exhaust gas dust is taken out from the flue and collected in the circulation tank. , The crude zinc oxide slurry stored in the same tank is sent by flowing through a sampling pipe.

The slurry in the circulation tank in the production process of zinc oxide ore is a slurry of crude zinc oxide dust, the slurry concentration is 5 g / L or more and 10 g / L or less, and the zinc content of crude zinc oxide dust is 30. It is 40% by weight or more and 40% by weight or less (based on the amount of dryness). The crude zinc oxide slurry is repeatedly circulated and used in the above cleaning treatment.

[Slurry flow device]
FIG. 1 is a diagram schematically showing the configuration of the slurry flow device of the present invention. The slurry flow apparatus 10 of the present invention can be preferably used as an apparatus for treating the crude zinc oxide slurry 6 generated in a production plant for obtaining zinc oxide ore from zinc-containing ore. More specifically, in the above-mentioned pre-cleaning performed during a series of exhaust gas treatment in the zinc oxide ore manufacturing process, the storage tank (circulation tank) can be used as a circulation tank and a drawing pipe for the slurry connected to the circulation tank. In the piping for flowing the slurry from, the adhesion of scale can be effectively suppressed.

The slurry flow device 10 is a device for flowing the crude zinc oxide slurry 6, and is formed at a position within a predetermined distance range from the storage tank 1, the sampling pipe 2, and the connection end of the sampling pipe 2 on the storage tank side. The scale inhibitor addition port 3 provided is an essential component. Further, it is preferable that the slurry flow device 10 is provided with a flow pump 4 whose suction side is connected to the side of the extraction pipe 2. A draft pipe 5 is further connected to the discharge side of the draft pump 4.

When the storage tank 1 is a large storage tank and the inner diameter of the extraction pipe 2 connected to the storage tank 1 is relatively narrow, the above-mentioned problem of scale generation occurs. Specifically, this problem is likely to occur when a sampling pipe having an inner diameter of 200 mm or less is connected to a storage tank having an inner diameter of 1000 mm or more, and the present invention is configured as such a storage tank and a sampling pipe. In addition, it can exert a particularly advantageous effect.

When the inner diameter of the flow pipe 5 is 200 mm or less, in order to clean the inside of the pipe, some flanges are removed and high-pressure water is sprayed from the tip of a special nozzle to perform jet cleaning, or some of the pipes are cleaned. There was no choice but to take time and effort to perform a special method such as pig cleaning, in which the flange was removed and a high pressure was applied to push the ball (pig) into the pipe. In some cases, the outer surface of the pipe was manually hit with a hammer and peeled off by the vibration. In addition, in these pipe cleaning work, since the pipe is long and often located in a high place, removing the flange, cleaning the jet, and manually tapping the pipe may be a dangerous work. Met. In order to prevent pipe blockage, that is, scale generation, a method of diluting with a large amount of water or a method of adjusting the pH of the target treated water can be considered, but the amount of water is increased, the use of chemicals, or It is not realistic because it involves the progress of an unfavorable reaction. The present invention also solves the above problems that occur when a pipe having an inner diameter of 200 mm or less is connected to a large storage tank.

The slurry flow device 10 is formed at a position where the scale inhibitor addition port 3 has a distance d (see FIG. 1) from the connection end of the extraction pipe 2 on the storage tank side of 0 mm or more and 100 mm or less. It is characterized by that. As a result, the scale inhibitor that has been conventionally supplied to the storage tank can be directly supplied to the extraction pipe 2 from an appropriate position without passing through the storage tank 1.

[Slurry flow method]
The slurry flow method of the present invention is a method of extracting the slurry from a large storage tank in which the crude zinc oxide slurry is stored and flowing it through the extraction pipe, which is particularly advantageous in preventing scale generation in the pipe. Is.

This slurry flow method can achieve the above-mentioned advantageous effect when the slurry stored in a storage tank having an inner diameter of 1000 mm or more is flown through a sampling pipe having an inner diameter of 200 mm or less connected to the side surface of the storage tank. It is a method, and as a specific implementation means, it can be implemented by using the above-mentioned slurry flow device 10. In the conventional method of flowing the slurry, in the same treatment step, the scale inhibitor, which has been directly supplied to the storage tank for collecting the treated water or the corresponding circulation tank, is removed from the storage tank of the extraction pipe 2. It is characterized in that it is directly supplied into the extraction pipe from the scale inhibitor addition port 3 installed at a position of 0 mm or more and 100 mm or less from the connection end on the side.

The scale inhibitor can be supplied into the extraction pipe 2 by press-fitting the scale inhibitor from the tank in which the scale inhibitor is stored into the scale inhibitor addition port 3 with a metering pump.

Here, when the scale inhibitor is supplied to the storage tank 1 as in the conventional case, the residence time in the storage tank 1 is longer than the residence time in the extraction pipe 2 and the flow-through pipe 5, and the storage tank 1 The anti-scale agent works inside. Assuming that the inner diameters of the extraction pipe 2 and the flow pipe 5 are 50 mm and the inner diameter of the storage tank 1 is 1000 mm, the residence time in the storage tank 1 is 400 times longer by simple calculation. Therefore, in the present invention, in the extraction pipe 2 connected to the side surface portion of the storage tank 1, the scale inhibitor is extracted pipe at a position where the distance from the connection end of the side surface portion of the storage tank 1 is 0 mm or more and 100 mm or less. It was decided to supply directly to the inside. By setting this supply position to a position where the distance from the connection end is within 100 mm, the scale inhibitor is sufficiently dispersed throughout the pipe including the vicinity of the connection end inside the pipe, and the scale is spread throughout the pipe. Can be sufficiently prevented from occurring. Further, the supplied scale inhibitor acts effectively only inside the extraction pipe 2 and the flow pipe 5.

In the practice of the present invention, when the scale inhibitor is supplied only to the inside of the extraction pipe 2 without supplying it to the storage tank 1 at all, the scale prevention effect on the inner wall of the storage tank 1 cannot be obtained, but it adheres. If the thickness of the scale to be used is 5 mm and the inner diameter of the storage tank 1 is 1000 mm, it is in a negligible range. On the other hand, if the inner diameters of the extraction pipe and the flow pipe are 50 mm, the actual inner diameter becomes 40 mm due to the adhesion of the scale of 5 mm, and even if it is assumed that the flow velocity of the slurry is the same, the flow rate is 0.6. It will be reduced to about twice, which will hinder the flow. Moreover, since the pressure loss increases, the flow rate further decreases. By supplying the anti-scale agent only to the inside of the extraction pipe 2 without supplying it to the storage tank 1 in this way, the amount of the anti-scale agent used can be suppressed to the minimum necessary amount.

Conventionally, as a scale inhibitor, a substance having a high effect of dissolving and dispersing is appropriately selected according to the scale component. For example, for calcium-based scale, a phosphate, a phosphonic acid compound, or the like is used. There is. Similarly, in the present invention, a conventionally known antiscale agent can be appropriately selected. For example, in the treatment for flowing the crude zinc oxide slurry, a scale inhibitor containing at least one of a chelating agent, a phosphonic acid, and a maleic acid-based polymer can be preferably used. Specific examples of such an antiscale agent include "Polyclin T-231 (trade name) (manufactured by Kurita Water Industries, Ltd.)" composed of two types of chelating agents, phosphonic acid, and maleic acid polymers.

The crude zinc oxide slurry to be treated is a crude zinc oxide slurry in which crude zinc oxide dust having a zinc content of 30% by weight or more and 70% by weight or less is suspended at a concentration of 1 g / L or more and 50 g / L or less. In some cases, it is preferable to adjust the supply amount of the above-mentioned antiscale agent containing various chelating agents and the like so as to have a concentration of 1 μL / L or more and 30 μL / L or less with respect to the crude zinc oxide slurry.

(Example)
Circulation tank, sampling pipe, flow pump, flow transfer of dry heating rotary kiln (DRK) exhaust gas pre-cleaning equipment in a zinc oxide production plant where the production of zinc oxide ore is 6 t / h or more and 10 t / h or less. The slurry flow device of the present invention was applied to the device composed of pipes, and the slurry flow method of the present invention was carried out. The slurry in the circulation tank (storage tank) is a slurry of crude zinc oxide dust, the slurry concentration thereof is 8 g / L or more and 10 g / L or less, and the zinc content of the crude zinc oxide dust is 30% by weight or more and 40% by weight or less. (Dry amount standard). As the scale inhibitor, Polyclin T-231 (trade name) (manufactured by Kurita Water Industries, Ltd.) was used and supplied so as to have a concentration of 10 μL / L with respect to the crude zinc oxide slurry. The inner diameter of the circulation tank was 2500 mm, the inner diameter of the sampling pipe was 80 mm, and the inner diameter of the draft pipe was 80 mm. Under the above conditions, the test operation to which the present invention was applied was continued for about one month. Approximately one month later, when the thickness of the scale generated in the pipe was measured at three places of the flow pipe, it was 4 mm on average.

(Comparison example)
Except for the fact that the anti-scale agent was directly supplied to the circulation tank, the test operation under the same conditions as in the examples was continued for about one month. After about 10 days, the flow rate of the slurry in the flow pipe decreased, and the amount of water in each place was adjusted. Approximately one month later, when the thickness of the scale generated in the pipe was measured at the same three places as in the example of the flow pipe, it was 15 mm on average.

From the above results, it can be seen that the present invention is a slurry flow means capable of suppressing scale adhesion more effectively than the conventional means in a narrow pipe for flowing the slurry from a large storage tank.

1 Storage tank 2 Extraction pipe 3 Scale inhibitor addition port 4 Flow pump 5 Flow pipe 6 Crude zinc oxide slurry 10 Slurry flow device

Claims (3)

A method for flowing a slurry in which a slurry stored in a storage tank having an inner diameter of 1000 mm or more is sent through a sampling pipe having an inner diameter of 200 mm or less connected to a side surface of the storage tank.
The scale inhibitor is directly supplied into the extraction pipe from the scale prevention agent addition port installed at a position of 0 mm or more and 100 mm or less from the connection end of the extraction pipe on the storage tank side.
The slurry is a crude zinc oxide slurry in which crude zinc oxide dust having a zinc content of 30% by weight or more and 70% by weight or less is suspended at a slurry concentration of 1 g / L or more and 50 g / L or less.
The scale inhibitor is a scale inhibitor containing at least one of a chelating agent, a phosphonic acid, and a maleic acid-based polymer, and is 1 μL / L or more and 30 μL / L or less with respect to the crude zinc oxide slurry. Adjusting the supply amount of the anti-scale agent so as to have a concentration,
Slurry flow method. The method for flowing a slurry according to claim 1, wherein the scale inhibitor is not supplied to the storage tank but is supplied only to the inside of the sampling pipe. The storage tank
The method for flowing a slurry according to claim 1 or 2, which is a tank for storing a crude zinc oxide slurry generated in a production plant for obtaining zinc oxide ore from a zinc-containing ore.

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