JP2013245119A - Concentrator for sulfuric acid liquid, method for concentrating sulfuric acid liquid, and method for collecting crude nickel sulfate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concentrator for a sulfuric acid liquid that suppresses damage of a heater by concentrating the sulfuric acid liquid.SOLUTION: A concentrator of a sulfuric acid liquid containing at least calcium includes: a first concentrator (10) for concentrating the sulfuric acid liquid; a heat exchanger (30) for heating the concentrated sulfuric acid liquid in the first concentrator (10) at a temperature lower than a boiling point; and a second concentrator (20) for decompressing the heated sulfuric acid liquid to evaporate water for concentration. By heating the sulfuric acid liquid at the temperature lower than the boiling point, evaporation of the sulfuric acid liquid in the heat exchanger (30) is suppressed and damage to the heat exchanger (30) can be suppressed.

Description

  The present invention relates to a sulfuric acid acidic liquid concentrator, a sulfuric acid acidic liquid concentration method, and a crude nickel sulfate recovery method.

  Sulfuric acid solution dissolves metals and is used in various industrial situations and plays an important role. One field in which an acidic sulfuric acid solution is used is a copper electrolytic purification process. In electrolytic refining of copper, a crude copper plate is used as an anode, a pure copper plate as a cathode, and an acidic copper sulfate aqueous solution as an electrolyte. Crude copper used as an anode in copper electrolytic refining contains impurities such as arsenic As, bismuth Bi, antimony Sb, nickel Ni, and these are eluted in the electrolytic solution. Some of these eluted impurities are deposited as mud copper slime on the bottom of the electrolytic cell. Impurities in the electrolytic solution are removed and collected by performing an appropriate treatment on the electrolytic solution extracted from the electrolytic cell. Specifically, excess copper in the electrolytic solution is removed by copper removal electrolysis, and arsenic, bismuth, antimony, and the like are removed from the electrolytic solution by clean electrolysis. Nickel in the electrolytic solution is crystallized as nickel sulfate by removing the copper solution after copper removal and cleaning, and can be removed and recovered from the electrolytic solution. Nickel sulfate removed from the electrolyte is called crude nickel sulfate because it contains a small amount of impurities.

  For example, Patent Document 1 discloses the recovery of nickel in the copper electrolyte. The method for recovering crude nickel sulfate disclosed in Patent Document 1 is to concentrate a copper removal electrolyte by heating with a vacuum evaporator, and then precipitate the crude nickel sulfate by cooling to separate the precipitated crude nickel sulfate into a solid-liquid separation. To separate and recover the crude nickel sulfate from the copper removal electrolyte. In the method for recovering crude nickel sulfate of Patent Document 1, the vacuum evaporator may have a single evaporator. However, a plurality of evaporators are arranged in series, and the vapor used in the previous stage is used for the latter stage evaporation. Adopting the multi-effect formula to be used, the evaporation efficiency can be increased.

  Patent Document 2 discloses a vapor compression type vacuum evaporation type concentrator. For example, the vapor compression vacuum evaporation concentrator disclosed in Patent Document 2 can be employed as the vacuum evaporation apparatus disclosed in Patent Document 1. In this case, the evaporation chamber of Patent Document 2 corresponds to the evaporator in Patent Document 1. In the vapor compression type vacuum evaporation type concentrating device of Patent Document 2, an aqueous solution to be heated and concentrated is circulated in an evaporation chamber kept in a vacuum state at atmospheric pressure or lower, and the aqueous solution is heated by an indirect heater provided in the evaporation chamber. . The indirect heater has a plurality of heat transfer tubes, and high pressure steam supplied from a boiler is connected to the heat transfer tubes. In the evaporation chamber, the aqueous solution is sprayed from the spray nozzle to the outer surface of the heat transfer tube, and the sprayed aqueous solution is heated and evaporated by the high-pressure steam in the heat transfer tube. The vapor evaporated from the aqueous solution joins the high-pressure steam from the boiler and is used as a heat source for heating the aqueous solution.

JP 2011-213502 A Japanese Patent Laid-Open No. 7-24202

By the way, when employ | adopting as a vacuum evaporation apparatus in the collection | recovery method of the crude nickel sulfate of patent document 1 the structure of the evaporation chamber which heat-exchanges a some heat exchanger tube and aqueous solution as shown in patent document 2 at a copper electrolytic solution There may be a problem with the concentration of the. That is, since the copper electrolytic solution is a sulfuric acid acidic solution in which metal ions are dissolved, sulfate is precipitated by increasing the concentration thereof. For example, calcium sulfate (CaSO ₄ ) is a representative example of sulfate precipitated from a copper electrolytic solution. When a copper electrolyte solution is sprayed on a heater having a plurality of heat transfer tubes and the copper electrolyte solution is concentrated, sulfate (for example, calcium sulfate) is deposited around the heat transfer tubes, and a scale is generated.

  FIG. 1 is a cross-sectional view of a heat transfer tube 101 when a sulfate scale is generated around the tube. When the sulfate scale 102 is generated around the heat transfer tube 101, the copper electrolytic solution enters the gap 103 between the heat transfer tube 101 and the scale 102. In the condition where the copper electrolytic solution reaches the boiling point, the copper electrolytic solution that has entered the gap 103 between the heat transfer tube 101 and the scale 102 is heated and evaporated by the steam in the heat transfer tube 101 and concentrated. As a result, the concentration of sulfuric acid locally increases, and the heat transfer tube 101 mainly composed of iron Fe (including other chromium Cr and nickel Ni) is corroded to cause cracks and breakage. As a result, steam leaks from the heat transfer tube, hindering the concentration process of the copper electrolyte solution, and the heater must be replaced. In particular, when the electrolytic solution that has already undergone the concentration step is introduced into the evaporator for further concentration, the conditions under which the sulfate is precipitated are easily satisfied, and a sulfate scale is easily formed. Further, such a phenomenon is considered to be a problem that occurs in the same manner when an acidic sulfuric acid solution in which a metal is dissolved is concentrated.

  Then, an object of this invention is to provide the sulfuric acid acidic liquid concentration apparatus which suppressed the damage of the heater by the concentration of sulfuric acid acidic liquid in view of said subject.

  The present invention that solves such a problem, in a concentration apparatus for a sulfuric acid solution containing at least calcium, comprises: a first concentrator that concentrates the sulfuric acid solution; and the sulfuric acid solution concentrated in the first concentrator is less than the boiling point. And a second concentrator for evaporating and condensing water by depressurizing the sulfuric acid acidic solution after heating. According to this structure, it is suppressed that a sulfuric acid acidic liquid evaporates in a heater. Thereby, the raise of a sulfuric acid concentration is suppressed and damage to a heater can be suppressed.

  In the sulfuric acid acidic liquid concentration apparatus, the sulfuric acid acidic liquid may be a copper electrolytic tail liquid. Further, in the sulfuric acid acidic liquid concentrating device, the first concentrator may be heated and concentrated in a decompressed room. In this case, in particular, the heater may heat the sulfuric acid acidic liquid using steam generated during the heat concentration of the sulfuric acid acidic liquid in the first concentrator. With this configuration, since the amount of steam supplied from the heat source can be reduced, damage to the heater can be suppressed while reducing the amount of energy consumed to concentrate the sulfuric acid acidic liquid.

  In the sulfuric acid acidic liquid concentrating device, the heater may heat the sulfuric acid acidic liquid using steam generated from waste heat of the copper smelting process. According to this structure, since the heat | fever which will be discarded in a copper smelting process is utilized, damage to a heater can be suppressed, utilizing energy effectively.

  The method for concentrating a sulfuric acid solution that solves the above problem is a method for concentrating a sulfuric acid solution that contains at least calcium. After the first concentration step of concentrating the sulfuric acid solution, the sulfuric acid solution is reduced to below the boiling point in the heating step. In the second concentration step after heating, the sulfuric acid acidic solution is decompressed to evaporate moisture and concentrated. According to this, it suppresses that a sulfuric acid acidic liquid evaporates during a heating process. As a result, an increase in sulfuric acid concentration can be suppressed, and problems in the concentration of sulfuric acid acidic liquid can be suppressed.

  In the sulfuric acid acidic liquid concentration method, the sulfuric acid acidic liquid may be a copper electrolytic tail liquid. Furthermore, in the sulfuric acid acidic liquid concentration method, in the first concentration step, the sulfuric acid acidic liquid may be heated and concentrated under reduced pressure. In this case, in particular, in the heating step, the sulfuric acid acidic liquid may be heated using steam generated from the sulfuric acid acidic liquid when heated and concentrated in the first concentration step. With this configuration, since the amount of steam supplied from the heat source can be reduced, it is possible to suppress problems in the concentration of the sulfuric acid acidic liquid while reducing the energy consumption for concentrating the sulfuric acid acidic liquid.

  In the method for concentrating sulfuric acid acidic solution, the heating step may heat the sulfuric acid acidic solution using steam generated from waste heat of the copper smelting step. According to this configuration, since heat that is discarded in the copper smelting process is used, problems in the concentration of the sulfuric acid acidic liquid can be suppressed while effectively using energy.

  In addition, the invention of a method for recovering crude nickel sulfate that solves the above problems and recovers crude nickel sulfate concentrates the electrolytic tail solution of copper containing nickel, and then cools and precipitates the crude nickel sulfate that has been cooled. In the method for recovering crude nickel sulfate recovered by liquid separation, after the electrolytic tail solution is concentrated, the electrolytic tail solution is heated at a temperature lower than the boiling point, the pressure is reduced to evaporate the water, and further concentration is performed. To do. Thereby, since the trouble in the concentration of the electrolytic tail solution is suppressed, nickel can be recovered efficiently.

  The sulfuric acid acidic liquid concentrator of the present invention can suppress damage to the heater due to the concentration of sulfuric acid acidic liquid.

It is the figure which showed the heat exchanger tube when the scale of a sulfate salt was produced | generated around the pipe | tube in the cross section. It is a flow showing the flow of the copper electrolysis tail liquid which concerns on collection | recovery of the crude nickel sulfate in embodiment. It is the figure which showed the concentration apparatus of embodiment. It is the figure which showed the concentration apparatus of the comparison form. It is the figure which showed the verification test result of the corrosion degree. It is the figure which showed the modification of the concentration apparatus of embodiment.

  An embodiment of the present invention will be described with reference to the drawings. In the embodiment of the present invention, a concentration device for concentrating an acidic sulfuric acid solution will be described. Here, the concentration device concentrates the tail liquid in the copper electrolytic purification process. However, it is possible to concentrate sulfuric acid acidic liquids other than the tail liquid in the copper electrolytic purification process by the same concentration apparatus. FIG. 2 is a flow showing the flow of tail liquid (hereinafter referred to as “electrolytic tail liquid”) in the copper electrolytic purification process related to the recovery of crude nickel sulfate in the present embodiment. In this embodiment, the electrolytic tail solution is introduced into a concentration device (hereinafter simply referred to as “concentration device”) 1 of an acidic sulfuric acid solution and concentrated. The concentrated electrolytic tail solution is sent to the submerged combustion can 2 and further concentrated. The electrolytic tail liquor highly concentrated in the concentrator 1 and the submerged combustion can 2 is introduced into the cooling tank 3 and cooled. By cooling, the crude nickel sulfate in the electrolytic tail solution is crystallized. The crystallized crude nickel sulfate is separated from the highly concentrated electrolytic tail solution by the solid-liquid separator 4. An example of the solid-liquid separator 4 is a filter press. The electrolytic tail solution is used in the copper electrolytic refining process, and after being eluted from copper ions, impurities such as arsenic, bismuth, antimony and nickel from the anode (mainly copper sulfate dissolved) It refers to a post-solution after a copper removal treatment for reducing the copper concentration. More preferably, after the copper removal treatment, the subsequent solution after performing a cleaning treatment for reducing impurities such as arsenic, bismuth, antimony, etc. is used as the electrolytic tail solution.

(Configuration of this embodiment)
FIG. 3 is a diagram showing the concentrating device 1 of the present embodiment. The concentrating device 1 includes a first concentrator 10, a second concentrator 20, and a heat exchanger 30.

  The first concentrator 10 is a vacuum evaporation type concentrator that supplies electrolytic tail liquor into a first vacuum steam can 12 incorporating a heat transfer section 11 therein, and concentrates the electrolytic tail solution in a state where the inside of the can is decompressed. It is. The heat transfer unit 11 includes a plurality of small-diameter heat transfer tubes 19. Steam supplied from a boiler or the like flows into the heat transfer tube 19. SUS316J1L is mentioned as an example of the material which comprises the heat exchanger tube 19. FIG. The heat transfer tube 19 has a length of φ19 mm and 2035 mm, and the heat transfer unit 11 may include 480 heat transfer tubes 19. In addition to the boiler, the heat transfer section 11 may be supplied with steam generated using waste heat discharged from a combustion furnace or other heat source, including a flash smelting furnace and a converter in a copper smelting process. Good.

  The first vacuum steam can 12 is a water tank on a sealed structure that prevents intrusion of outside air. For example, SUS836L or NAS254N is used as the material of the first vacuum steam can 12. The first vacuum steam can 12 has a semi-cylindrical shape in which a cylinder having a diameter of 2400 mm and a depth of 2000 mm is divided in half by a plane passing through the axis in a state where the axis of the cylinder is tilted so as to be horizontal. The electrolytic tail solution supplied into the first vacuum steam can 12 is stored at the bottom of the can. The electrolytic tail liquor stored at the bottom of the first vacuum steam can 12 is conveyed by the first pump 13 to the spray nozzle 14 provided at the ceiling of the first vacuum steam can 12. The spray nozzle 14 is disposed so as to spray the electrolytic tail solution toward the heat transfer tube 19. The electrolytic tail liquor on the outer surface of the heat transfer tube 19 sprayed from the spray nozzle 14 rises in temperature by receiving heat from the steam flowing in the heat transfer tube 19, and the water in the solution is evaporated and concentrated. The electrolytic tail liquor thus concentrated again accumulates at the bottom in the first vacuum steam can 12. The electrolytic tail liquor collected at the bottom in the first vacuum steam can 12 is again transported to the spray nozzle 14 and sprayed to the heat transfer tube 19, repeatedly receiving heat, and further concentrated. Thus, the 1st concentrator 10 performs the 1st concentration process which concentrates electrolytic tail liquid. Since the inside of the first vacuum steam can 12 is adjusted to a state where the pressure is lower than the atmospheric pressure, moisture in the electrolytic tail liquor is easier to evaporate than when heating at atmospheric pressure, and the electrolytic tail liquid is concentrated. Is suitable. Further, in this case, since water easily evaporates, the temperature of the vapor may be lower than in the case of evaporating at atmospheric pressure. For this reason, the amount of heat imparted to the steam in the heat source can be reduced. The steam generated in the first vacuum steam can 12 is supplied to the heat exchanger 30.

  A part of the electrolytic tail liquor circulating in the first concentrator 10 is supplied to the second vacuum steam can 22 of the second concentrator 20 through the supply pipe 15. Similar to the first vacuum steam can 12, the second vacuum steam can 22 is a water tank on a sealed structure that prevents the intrusion of outside air. The second vacuum steam can 22 is made of the same material as the first vacuum steam can 12 and has the same size and shape. The electrolytic tail solution supplied into the second vacuum steam can 22 is stored at the bottom of the can. The electrolytic tail liquor stored at the bottom of the second vacuum steam can 22 is supplied to the heat exchanger 30 by the second pump 23.

  The heat exchanger 30 is a heater that heats the electrolytic tail liquor below the boiling point. The heat exchanger 30 has a configuration in which a plurality of small-section pipes 32 are provided in parallel in a hollow body 31. Steam generated in the first vacuum steam can 12 is taken into the main body 31. The electrolytic tail solution pumped by the second pump 23 flows into the pipe 32. In the heat exchanger 30, heat is transferred from the steam outside the pipe 32 to the electrolytic tail liquor flowing in the pipe 32, the steam condenses into a liquid (water), and the temperature of the electrolytic tail liquid rises. Thus, the heat exchanger 30 performs the heating process which heats the electrolytic tail liquor after the first concentration process below the boiling point. Further, the vapor generated in the first vacuum steam can 12 is condensed into a liquid in the heat exchanger 30 to become a negative pressure, and the inside of the first vacuum steam can 12 is decompressed.

  The electrolytic tail liquor heated in the heat exchanger 30 is sent to the spray nozzle 24 provided on the ceiling of the second vacuum steam can 22 and sprayed from the spray nozzle 24 into the second vacuum steam can 22. The second vacuum steam can 22 is provided with a vacuum pump 25 for drawing steam, and the inside of the second vacuum steam can 22 is depressurized from the atmospheric pressure. Thus, since the inside of the second vacuum steam can 22 is depressurized from the atmospheric pressure and the electrolytic tail liquor sprayed inside is heated in the heat exchanger 30, the evaporation of moisture is promoted, The concentration of the electrolytic tail solution increases. The electrolytic tail liquor thus concentrated is supplied again to the heat exchanger 30 by the second pump 23, heated, and further concentrated while circulating in the decompressed second concentrator 20. Thus, the 2nd concentrator 20 performs the 2nd concentration process which decompresses the electrolytic tail liquid after a heating process, evaporates a water | moisture content, and concentrates. A part of the electrolytic tail solution thus concentrated is taken out from the downstream side of the second pump 23 and sent to the next step. A condenser 26 is provided between the vacuum pump 25 and the second vacuum steam can 22, and the steam drawn from the second vacuum steam can 22 by the vacuum pump 25 in the condenser 26 is liquid (water). Condenses to

(Configuration of comparison form)
Next, the configuration of the comparative form will be described. FIG. 4 is a diagram showing a sulfuric acid acid concentration apparatus (hereinafter simply referred to as “concentration apparatus”) 200 of a comparative form. The concentrating device 200 includes a first concentrator 210 and a second concentrator 220. The 1st concentrator 210 is the structure similar to the 1st concentrator 10 of the said embodiment. Therefore, in FIG. 4, the same reference numerals are assigned to the same components as those of the first concentrator 10, and detailed description thereof is omitted.

  The concentrating device 200 does not include a device corresponding to the heat exchanger 30 in the above embodiment. Instead, the second concentrator 220 includes the second heat transfer unit 221 in the second vacuum steam can 222. The second heat transfer unit 221 includes a plurality of small-diameter heat transfer tubes 229. SUS316J1L is mentioned as an example of the material which comprises the heat exchanger tube 229. The heat transfer tube 229 has a length of φ19 mm and 2035 mm, and the second heat transfer unit 221 may include 480 heat transfer tubes 219. Steam generated in the first vacuum steam can 12 is taken into the heat transfer tube 229. The second vacuum steam can 222 is a water tank on a sealed structure that prevents intrusion of outside air. The second vacuum steam can 222 is made of the same material as the first vacuum steam can 12 and has the same size and shape.

  The electrolytic tail solution concentrated in the first concentrator 210 is supplied into the second vacuum steam can 222 and stored in the bottom of the can. The electrolytic tail liquor stored at the bottom of the second vacuum steam can 222 is transported by the second pump 223 to the spray nozzle 224 provided at the ceiling of the second vacuum steam can 222. The spray nozzle 224 is arranged to spray the electrolytic tail solution toward the heat transfer tube 229. The electrolytic tail liquor on the outer surface of the heat transfer tube 229 sprayed from the spray nozzle 224 rises in temperature by receiving heat from the steam flowing in the heat transfer tube 229, and the water in the electrolytic tail solution is evaporated and concentrated. . The electrolytic tail liquor thus concentrated again accumulates at the bottom of the second vacuum steam can 222, is again transported to the spray nozzle 224, sprayed onto the heat transfer tube 229, and repeatedly receives heat, and further concentrated. .

  The second vacuum steam can 222 is provided with a vacuum pump 225 for drawing steam, and the inside of the second vacuum steam can 222 is depressurized from the atmospheric pressure. Therefore, the water in the electrolytic tail liquor in the second vacuum steam can 222 is more likely to evaporate than when heated at atmospheric pressure, and the electrolytic tail liquor is more likely to be concentrated. Further, a condenser 226 is provided between the vacuum pump 225 and the second vacuum steam can 222, and the steam drawn from the second vacuum steam can 222 by the vacuum pump 225 in the condenser 226 is a liquid (water). Condenses to

  As described above, the concentrator 200 of the comparative form has a structure in which concentrators that heat and concentrate in a decompressed room are arranged in series. This configuration is efficient because the steam generated in the previous stage is used in the subsequent stage, so that the amount of energy used for concentration can be suppressed. However, there is room for improvement in the points described in the following examples.

(Example)
Next, examples of the present invention will be described while comparing the embodiment and the comparative embodiment.

The liquidity of the electrolytic tail solution to be concentrated in the concentration apparatus 1 of the present embodiment and the concentration apparatus 200 of the comparative form is that the sulfuric acid concentration before concentration is 250 to 280 g / L, the Ni concentration is 20 g / L, and the Cu concentration is 0. In addition to this, 0.35 g / L of calcium Ca is contained. The daily processing amount of the concentration apparatus 1 and the concentration apparatus 200 is 55 m ³ , and the concentration ratio of the electrolytic tail solution is 2.0 times. In the concentration apparatus 1 of this Embodiment, the temperature of the electrolytic tail liquid in the heat transfer part 11 in the 1st concentrator 10 is 60-80 degreeC, and the temperature of the electrolytic tail liquid in the heat exchanger 30 is 50-70 degreeC. . In the concentration device 200 of the comparative form, the temperature of the electrolytic tail liquor in the heat transfer section 11 in the first concentrator 210 is 60 to 80 ° C., and the temperature of the electrolytic tail liquor in the second heat transfer section 221 of the second concentrator 220. Is 50-70 degreeC.

  In both the embodiment described above and the comparative example, the electrolytic tail solution is concentrated in the first concentrators 10 and 210. Therefore, if the second concentrators 20 and 220 concentrate the electrolytic tail solution, Calcium concentration and sulfuric acid concentration increase and exceed the precipitation limit of calcium sulfate. That is, calcium sulfate in the electrolytic tail solution is concentrated to a solubility product or more, and calcium sulfate is precipitated.

  When the concentrating device 200 of the comparative form was operated for about three months, corrosion occurred in the heat transfer tube 229 of the second heat transfer section 221 of the second concentrator 220. In the comparative form, the condition in which the electrolytic tail solution reaches the boiling point is satisfied in the second concentrator 220, so that the electrolytic tail solution is excessively concentrated. Thus, the excessive increase in the sulfuric acid concentration is the cause of the corrosion in the heat transfer tube 229. Corrosion of the heat transfer tube 229 occurred throughout the second heat transfer portion 221 and steam leakage occurred in about 40% of the heat transfer tube 229. If steam leaks from the heat transfer tube 229, the concentration process of the electrolytic tail solution is hindered, and the second heat transfer unit 221 must be replaced. In the first concentrator 210, calcium sulfate scale and corrosion did not occur. That is, after concentrating the electrolytic tail liquor after the copper removal and cleaning treatment, and further heating and concentrating at a temperature that is equal to or higher than the boiling point in a reduced pressure state, the concentration of the electrolytic tail liquid is excessively increased, and Problems arise.

  In the comparative form, in the second heat transfer section 221 of the second concentrator 220, the electrolytic tail solution is concentrated, and the calcium concentration and the sulfuric acid concentration in the electrolytic tail solution are equal to or higher than the solubility product of calcium sulfate. A scale of calcium sulfate was formed around the heat transfer tube 229. Furthermore, in the comparative form, since the second concentrator 220 is heated and concentrated in a reduced pressure state, the sulfuric acid solution reaches the boiling point, the evaporation of water in the electrolytic tail liquid is promoted, and the electrolytic tail liquid becomes excessive. It has been concentrated.

  Here, a verification test of the corrosion degree of stainless steel (SUS316J1L) with sulfuric acid will be described. Stainless steel (SUS316J1L) is an example of a material that forms the heat transfer tube 19 of the heat transfer unit 11 of the concentrator 1, the pipe 32 of the heat exchanger 30, and the heat transfer tube 229 of the second heat transfer unit 221 of the concentrator 200. is there. FIG. 5 is a diagram showing the result of the corrosion degree verification test. The verification test of the corrosion degree was performed using a test piece of SUS316J1L. The immersion time of the test piece was 120 hours, and the test was performed on two points of sulfuric acid temperature of 60 ° C. and 80 ° C. The concentration of sulfuric acid is 580 g / L, 686 g / L, 844 g / L corresponding to 2.0 times, 2.5 times, 3.0 times, and 3.5 times of the electrolytic tail solution before being concentrated in the above apparatus, The test was conducted by changing to four stages of 922 g / L. As a result of the verification test of the degree of corrosion, it is judged that the corrosion amount per year is 0.05 mm or less, the complete corrosion resistance of the heat transfer tube is maintained, and the heat transfer tube can be used at 0.07 mm or less. If the amount of corrosion per year exceeds 0.07 mm, it is determined that there is a risk of damage to the heat transfer tubes.

  This verification test resulted in a higher degree of corrosion when the temperature was 80 ° C. than when the temperature was 60 ° C. at all sulfuric acid concentrations. When the sulfuric acid concentration was 844 g / L or 922 g / L, the heat transfer tube was damaged. According to the consideration based on this result, the electrolytic tail solution is concentrated around the heat transfer tube 229 of the second concentrator 220 of the comparative form, and as a result, the electrolytic tail is concentrated up to the concentration of sulfuric acid at which there is a risk of damage to the heat transfer tube 229. It is thought that the liquid was concentrated.

  On the other hand, in the present embodiment, the heat exchanger 30 heats the electrolytic tail liquor below the boiling point. For this reason, compared with the case where it heats at the temperature more than a boiling point like a comparative form, evaporation of the water | moisture content of the electrolytic tail liquid in the heat exchanger 30 is suppressed. For this reason, it is suppressed that the density | concentration of electrolytic tail liquid rises excessively in the piping which comprises the piping 32 of the heat exchanger 30. FIG. For this reason, since the electrolytic tail solution is not concentrated to a dangerous concentration that damages the pipe, damage to the heat exchanger is prevented. The electrolytic tail solution heated in the heat exchanger 30 evaporates in the second vacuum steam can 22, which is located downstream of the heat exchanger 30, and the electrolytic tail solution is evaporated. Concentrate. At this time, the concentration of calcium and sulfuric acid in the electrolytic tail liquor in the second vacuum steam can 22 exceeds the precipitation limit concentration of calcium sulfate, and calcium sulfate is deposited in the second vacuum steam can 22. However, since the heat transfer tube is not arranged in the second vacuum steam can 22, it is not necessary to consider the tube damage due to the calcium sulfate scale formation.

  As described above, according to the present embodiment, in the electrolytic tail solution concentrating device for concentrating the electrolytic tail solution of copper, the first concentrator 10 for concentrating the electrolytic tail solution and the first concentrator 10 are concentrated. A heat exchanger 30 that heats the electrolytic tail liquor below the boiling point, and a second concentrator 20 that depressurizes the heated electrolytic tail liquor to evaporate and concentrate the water, and heats the electrolytic tail liquor below the boiling point. By doing this, it is possible to suppress evaporation of the electrolytic tail liquor in the heat exchanger 30. Thereby, it is suppressed that the sulfuric acid density | concentration of electrolytic tail liquid becomes the density | concentration which damages piping. As a result, damage to the piping of the heat exchanger 30 can be suppressed.

  Thus, the concentration of the electrolytic tail solution containing nickel is performed without any trouble, whereby the recovery of the crude nickel sulfate can be performed efficiently. As a result, the nickel concentration in the electrolytic solution is reduced, the liquid resistance in the electrolytic solution in the copper refining process is reduced, and the electrolytic refining of copper can be stably operated. In addition, profit from sales of crude nickel sulfate can be increased.

  In addition, the concentration apparatus 1 in the said embodiment is good also as supplying the smelting process waste heat recovery steam to the heat exchanger 30, as shown in FIG. Smelting process waste heat recovery steam is steam generated from waste heat generated in copper smelting. For example, steam generated from waste heat discharged from a flash smelting furnace, converter, or other smelting furnace in copper smelting may be used. Moreover, the steam which generate | occur | produced by collect | recovering the heat | fever which generate | occur | produces when manufacturing a sulfuric acid from the exhaust gas of a flash smelting furnace or a converter with a boiler may be sufficient. Further, the first concentrator 10 may not be a concentrator that performs heat concentration in a reduced pressure state. For example, a concentrator that performs submerged combustion may be used.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

DESCRIPTION OF SYMBOLS 1 Concentrator 10 First concentrator 20 Second concentrator 30 Heat exchanger (heater)

Claims (11)

In the sulfuric acid acid concentration apparatus containing at least calcium,
A first concentrator for concentrating the sulfuric acid acidic solution;
A heater that heats the acidic sulfuric acid solution concentrated in the first concentrator below a boiling point;
A second concentrator for evaporating and condensing the sulfuric acid acidic solution after heating to evaporate the water;
An apparatus for concentrating sulfuric acid acidic liquid, comprising:   2. The sulfuric acid acidic liquid concentrator according to claim 1, wherein the sulfuric acid acidic liquid is an electrolytic tail solution of copper.   The concentration apparatus for an acidic sulfuric acid solution according to claim 1 or 2, wherein the first concentrator performs heat concentration in a decompressed room.   The apparatus for concentrating a sulfuric acid acidic liquid according to claim 3, wherein the heater heats the sulfuric acid acidic liquid using steam generated during the heat concentration of the sulfuric acid acidic liquid in the first concentrator.   5. The sulfuric acid acidic liquid concentrating device according to claim 1, wherein the heater heats the sulfuric acid acidic liquid using steam generated from waste heat of a copper smelting process. 6. . In a method for concentrating a sulfuric acid acidic solution containing at least calcium,
After the first concentration step of concentrating the sulfuric acid acidic solution, the sulfuric acid acidic solution is heated below the boiling point in the heating step, and after the heating step, the sulfuric acid acidic solution is depressurized in the second concentration step to evaporate water, and concentrated. A method of concentrating a sulfuric acid acidic liquid characterized by comprising:   The method for concentrating a sulfuric acid acidic solution according to claim 6, wherein the sulfuric acid acidic solution is an electrolytic tail solution of copper.   The method for concentrating a sulfuric acid acidic solution according to claim 6 or 7, wherein, in the first concentration step, the sulfuric acid acidic solution is concentrated by heating while reducing the pressure.   9. The sulfuric acid acidic liquid according to claim 8, wherein, in the heating step, the sulfuric acid acidic liquid is heated using steam generated from the sulfuric acid acidic liquid when heated and concentrated in the first concentration step. Concentration method.   The said heating process heats the said sulfuric acid acidic liquid using the vapor | steam generated from the waste heat of a copper smelting process, The concentration method of the sulfuric acid acidic liquid as described in any one of Claim 6 to 9 characterized by the above-mentioned. . In the method for recovering crude nickel sulfate, after concentrating the electrolytic tail solution of copper containing nickel, the crude nickel sulfate recovered by cooling and solid-liquid separation is collected.
A method for recovering crude nickel sulfate, comprising concentrating the electrolytic tail liquor, heating the electrolytic tail liquor below the boiling point, depressurizing to evaporate water, and further concentrating.

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