JP2019039034A - Anticorrosive tank - Google Patents

Abstract

To provide an anticorrosive tank with high anticorrosiveness.SOLUTION: An anticorrosive tank 1 comprises a bottom part 11 and a sidewall 12 vertically arranged in the circumference of the bottom part 11. Each of the bottom part 11 and the sidewall 12 comprises: a metal shell 21 formed with metal; a fluororesin layer 22 formed with fluororesin, being provided on the inner surface of the metal shell 21; and a brick layer 24 formed with bricks, being positioned at the inner side of the fluororesin layer 22. Content liquid can be inhibited from reaching the metal shell 21 by the fluororesin layer 22 even when the content liquid is immersed into the brick layer 24. Therefore, the metal shell 21 is protected from corrosion, whereby the anticorrosive tank 1 can keep anticorrosive with high anticorrosiveness.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a corrosion-resistant tank. More specifically, the present invention relates to a corrosion-resistant tank having corrosion resistance against high temperature, high concentration sulfuric acid and the like.

  In the electrolytic purification of copper, a plurality of anodes and cathodes are alternately inserted into an electrolytic cell using crude copper containing impurities as an anode and a thin plate of pure copper, stainless steel, or titanium as a cathode. While supplying an electrolytic solution to the electrolytic cell, current is passed between the anode and the cathode, and copper is electrodeposited on the cathode to obtain electrolytic copper.

  Copper contained in the anode is eluted into the electrolyte as copper ions. At the same time, impurities such as arsenic, bismuth, antimony and nickel contained in the anode are also eluted into the electrolyte. At the cathode, only copper ions in the electrolyte are electrodeposited on the cathode. Therefore, high purity electrolytic copper can be obtained.

  Since the impurities eluted from the anode remain in the electrolytic solution, the impurity concentration of the electrolytic solution increases as electrolytic purification proceeds. If the concentration of impurities in the electrolyte increases, the impurities co-deposit with copper, reducing the copper quality of the electrolytic copper, causing scale in the electrolyte piping, hindering operation, and reducing the electrical conductivity of the electrolyte. Such as increasing the power cost. Therefore, the electrolytic solution is sent to the liquid purification process to remove impurities.

  The liquid purification process in the electrolytic purification of copper is performed as follows. The electrolyte discharged from the electrolytic cell is concentrated by evaporation in vacuo, and the supersaturated copper is precipitated and removed as crude copper sulfate by rapid cooling. Next, copper removal electrolysis is performed to remove residual copper, arsenic, bismuth, and antimony by depositing on the cathode. The obtained copper removal electrolytic solution is heated in an electric evaporation tank to evaporate the water and concentrated, and then cooled to precipitate crude nickel sulfate, which is separated and removed by filtration. The obtained post-nickel removal solution is supplied again to the electrolytic cell (for example, Patent Document 1).

  In the nickel removal step, the graphite electrode rod is immersed in the copper removal electrolyte supplied to the electric evaporation tank and energized, and the copper removal electrolyte is heated by Joule heat to evaporate the moisture. During the concentration process, the copper removal electrolyte becomes a high-temperature, high-concentration nickel sulfate aqueous solution, which is highly corrosive. If the electric evaporation tank corrodes and the hole is opened, problems such as leakage of nickel sulfate aqueous solution occur.

JP 2014-101546 A

  An object of this invention is to provide a corrosion-resistant tank with high corrosion resistance in view of the said situation.

A corrosion-resistant tank according to a first aspect of the present invention includes a bottom portion and side walls erected on the periphery of the bottom portion, and the bottom portion and the side walls are respectively applied to a metal shell formed of metal and an inner surface of the metal shell. A fluororesin layer formed of a fluororesin; and a brick layer located inside the fluororesin layer and formed of a brick.
The corrosion-resistant tank of the second invention is characterized in that, in the first invention, the fluororesin layer is formed by coating the metal shell with a fluororesin.
The corrosion-resistant tank of the third invention is characterized in that, in the first or second invention, the bottom part and the side wall are each provided with a heat insulating layer located between the fluororesin layer and the brick layer.
According to a fourth aspect of the present invention, in the first, second or third aspect, the metal shell of the side wall has a flange portion at an upper edge, and the fluororesin layer of the side wall has the flange portion. It is characterized by covering the seat surface.
According to a fifth aspect of the present invention, in the first, second or third aspect of the invention, the corrosion-resistant tank includes a discharge portion which protrudes outward from the outer surface of the side wall and has a flow path for content liquid, and the bottom portion of the discharge portion is formed of metal. A metal layer formed on the upper surface of the metal shell and formed of a fluororesin, and a brick layer positioned above the fluororesin layer and formed of a brick. The metal shell of the part has a flange part at the tip, and the fluororesin layer of the discharge part covers the seating surface of the flange part.
According to a sixth aspect of the present invention, there is provided a corrosion-resistant tank according to the first, second or third aspect of the present invention, comprising a discharge portion protruding outward from the outer surface of the side wall and having a content liquid flow path, wherein the bottom portion of the discharge portion is made of metal. A metal layer formed on the upper surface of the metal shell and formed of a fluororesin, and a brick layer positioned above the fluororesin layer and formed of a brick. The thickness of the brick layer constituting the bottom of the wall is 0.5 to 1.5 times the thickness of the brick layer of the side wall.

According to the first invention, even if the content liquid penetrates the brick layer, the content liquid can be prevented from reaching the metal shell by the fluororesin layer. Therefore, the metal shell is difficult to corrode and the corrosion resistance of the corrosion-resistant tank can be increased.
According to the second invention, since the fluororesin layer formed by coating is seamless, deformation, deterioration, and breakage of the fluororesin layer can be suppressed. Therefore, the corrosion resistance of the corrosion resistant tank can be further increased.
According to the third invention, since the heat of the content liquid is blocked by the heat insulating layer, the fluororesin layer can be kept at a low temperature, and deterioration of the fluororesin layer can be suppressed.
According to the fourth invention, since the fluororesin layer covers the seating surface of the flange portion, corrosion of the flange portion can be suppressed.
According to the fifth aspect, since the fluororesin layer covers the seating surface of the flange portion, corrosion of the flange portion can be suppressed.
According to the sixth aspect of the invention, since the thickness of the brick layer at the bottom of the discharge part is approximately the same as the thickness of the brick layer on the side wall, the discharge part can withstand loads due to thermal expansion and contraction.

It is a longitudinal cross-sectional view of the corrosion-resistant tank which concerns on one Embodiment of this invention. It is explanatory drawing of the laminated structure of the bottom part, side wall, and discharge part of the corrosion-resistant tank of FIG. It is the A section enlarged view in FIG. It is the B section enlarged view in FIG. 3 is a longitudinal sectional view of a corrosion-resistant tank of Example 2. FIG. It is explanatory drawing of a nickel removal installation.

Next, an embodiment of the present invention will be described with reference to the drawings.
In the electrolytic purification of copper, a liquid purification process for removing impurities from the electrolytic solution is performed. The liquid purification process includes a nickel removal process. The corrosion-resistant tank which concerns on one Embodiment of this invention is used for the nickel removal installation which performs a nickel removal process.

(Nickel removal equipment)
The nickel removal step is performed with the equipment shown in FIG. The nickel removal equipment has an electric evaporation tank 110. A copper removal electrolyte is supplied to the electric evaporation tank 110. The copper removal electrolytic solution is a solution obtained by removing copper from the electrolytic solution, and is a crude nickel sulfate aqueous solution. The copper removal electrolytic solution is preheated to 50 to 90 ° C. and then supplied to the electric evaporation tank 110.

  The electric evaporation tank 110 is a cylindrical tank whose upper part is covered with a lid 111. The lid 111 is provided with a supply port for supplying a copper removal electrolyte into the electric evaporation tank 110. The lid 111 is formed with insertion holes at a plurality of positions with a predetermined interval, and a graphite electrode rod 112 is inserted into each of the holes. Each graphite electrode rod 112 is immersed in a copper removal electrolytic solution in the electric evaporation tank 110. An electric wire (not shown) is connected to the graphite electrode rod 112. By passing a current between the graphite electrode rods 112 through the electric wires, the copper removal electrolyte in the electric evaporation tank 110 is energized. Thus, the copper removal electrolyte is heated by Joule heat to evaporate and concentrate the water. The heating temperature of the copper removal electrolytic solution in the electric evaporation tank 110 may be a temperature equal to or higher than the boiling point of the copper removal electrolytic solution, but is usually 150 to 200 ° C.

  A trough 113 is connected to the side wall of the electric evaporation tank 110. In the concentrated copper removal electrolyte, crude nickel sulfate crystals are deposited to form a slurry. This slurry is guided to the cooling crystal tank 120 through the basket 113.

  The slurry discharged from the electric evaporation tank 110 is cooled in the cooling crystal tank 120. As a result, the solubility is remarkably lowered, and crude nickel sulfate crystals are further precipitated in the slurry. The slurry is discharged from the cooling crystal tank 120 and separated into solid and liquid by the filter 130 to recover the crude nickel sulfate crystals.

  The recovered crude nickel sulfate crystals are stored in a container 140. On the other hand, the filtrate is stored in the receiver tank 150. The filtrate stored in the receiver tank 150 is discharged out of the system or reused as sulfuric acid to replenish the electrolyte.

(Corrosion-resistant tank)
In the electric evaporation tank 110, a high-temperature and high-concentration crude nickel sulfate aqueous solution is produced. Therefore, the electric evaporation tank 110 needs to have corrosion resistance against high temperature and high concentration sulfuric acid. A corrosion-resistant tank 1 according to an embodiment of the present invention is used for the electric evaporation tank 110.

  As shown in FIG. 1, the electric evaporation tank 110 includes a corrosion-resistant tank 1 as a tank body and a lid 111 that covers an upper opening of the corrosion-resistant tank 1. The corrosion-resistant tank 1 is a substantially cylindrical tank composed of a bottom 11 and a side wall 12 standing on the periphery of the bottom 11.

  A part of the side wall 12 is provided with a discharge portion 13 that protrudes outward from the outer surface thereof. A flow path 14 through which the content liquid (crude nickel sulfate aqueous solution) of the corrosion-resistant tank 1 flows is formed in the discharge part 13. The flow path 14 reaches the inner surface of the side wall 12 and communicates the inside and the outside of the corrosion-resistant tank 1. The concentrated crude nickel sulfate aqueous solution is discharged out of the corrosion-resistant tank 1 through the flow path 14 together with the crystals. A hook 113 is connected to the tip of the discharge unit 13.

  The flow path 14 of the discharge unit 13 has an inclination that decreases toward the outside of the corrosion-resistant tank 1. Further, the ridge 113 also has an inclination that decreases toward the outside of the corrosion-resistant tank 1. Therefore, the content liquid naturally flows down according to the inclination of the flow path 14 and the ridge 113.

  In addition, the discharge part 13 may have a cylindrical shape in which a hole-like flow path 14 is formed, or may have a bowl shape in which the upper part of the groove-shaped flow path 14 is opened. Regardless of the shape, the discharge part 13 has a bottom part 13a in contact with the content liquid.

  The trough 113 is connected to the corrosion-resistant tank 1 at a position away from the outer surface of the side wall 12. Therefore, even if the discharge part 13 and the flange 113 are not sufficiently adhered and a gap is formed in the connection part, the crude nickel sulfate aqueous solution leaking from the connection part does not travel along the outer surface of the side wall 12, and the side wall 12 is wide. There is no risk of corrosion of the area.

  The bottom part 11 and the side wall 12 are each comprised from the metal shell 21 which comprises the outermost layer, and the brick layer 24 which comprises the innermost layer. Moreover, the bottom 13a of the discharge part 13 is composed of a metal shell 21 constituting the lowermost layer and a brick layer 24 constituting the uppermost layer. The metal shell 21 is made of a metal such as stainless steel and constitutes the outer shape of the corrosion-resistant tank 1.

  The brick layer 24 is formed by stacking acid-resistant bricks. The brick layer 24 may be formed by laminating a plurality of bricks or may be formed by one layer. In addition, joint material is applied and filled around each brick in order to fix the adhesive and prevent liquid from entering.

  As shown in FIG. 2, a fluororesin layer 22 and a heat insulating layer 23 are disposed between the metal shell 21 and the brick layer 24 that constitute the bottom portion 11, the side wall 12, and the discharge portion 13. That is, the metal shell 21, the fluororesin layer 22, the heat insulation layer 23, and the brick layer 24 are laminated in this order.

  The fluororesin layer 22 is applied to the inner surface (upper surface) of the metal shell 21. The fluororesin layer 22 is made of a fluororesin such as PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), PTFE (tetrafluoroethylene), FEP (tetrafluoroethylene / hexafluoropropylene copolymer). Has been. Among fluororesins, it is preferable to use PFA and PTFE having high heat resistance.

  If the fluororesin layer 22 is too thin, the strength becomes weak. Conversely, if it is too thick, the fluororesin layer 22 is easily peeled off from the metal shell 21 due to the difference in thermal expansion coefficient between the metal shell 21 and the fluororesin layer 22. Therefore, the thickness of the fluororesin layer 22 is preferably 1 to 10 mm.

  As a method of forming the fluororesin layer 22, there are sheet lining and coating lining. Sheet lining is a method of attaching a plurality of fluororesin sheets to the metal shell 21. Coat lining is a method of coating the metal shell 21 with a fluororesin by applying a fluororesin agent having a low polymerization degree, such as a monomer, with a brush or the like to cause a polymerization reaction. Since the polymerization reaction requires a certain temperature, after applying the fluororesin agent, it is heated with a hair dryer or the like to cause the polymerization reaction. It is also possible to cause a polymerization reaction with heat accompanying use of the electric evaporation tank 110.

  In the case of sheet lining, a seam is generated between the fluororesin sheets. This seam is a chemically, mechanically and thermally weak part, and is the starting point for deformation, deterioration and breakage. Specifically, since the fluororesin sheet does not have enough activity to start the reaction, the joint of the fluororesin sheet becomes a chemically weak part without bonding. Further, only a flat sheet of fluororesin sheet is distributed, and it is necessary to make a curved surface or a bent side in accordance with the shape of the metal shell 21. When a curved surface or a bent side is formed on the fluororesin sheet, stress is applied to the seam of the fluororesin sheet, resulting in a mechanically weak portion. Furthermore, since it is difficult to line the fluororesin sheet and the adhesive with the same components and purity, and the difference in average molecular length and density occurs, the seam of the fluororesin sheet becomes a portion that is vulnerable to thermal expansion. Therefore, when adopting sheet lining, it is preferable to lining the fluororesin sheet with a plurality of layers.

  On the other hand, in the case of coating lining, since the application of the fluororesin agent to the entire metal shell 21 is completed before the polymerization is substantially completed, no seam is formed in the fluororesin layer 22. In addition, since deformation such as bending of the sheet is not required, the fluororesin is welded to the metal shell 21. Furthermore, even if the production lots of the fluororesin agent are different, the characteristics related to thermal expansion such as average molecular length and density can be kept uniform by stirring and mixing. Therefore, a portion where stress concentrates on the fluororesin layer 22 does not occur, and deformation, deterioration, and breakage of the fluororesin layer 22 can be suppressed. As a result, the corrosion resistance of the corrosion-resistant tank 1 can be further increased.

  The heat insulation layer 23 is formed of a material having heat insulation properties such as fibers such as glass cloth. The heat insulating layer 23 may be formed of an air layer. Fluoropolymers are vulnerable to relatively high temperatures. By disposing the heat insulating layer 23 between the fluororesin layer 22 and the brick layer 24, the heat of the content liquid transmitted from the brick layer 24 can be blocked by the heat insulating layer 23. Therefore, the fluororesin layer 22 can be kept at a low temperature close to the temperature of the metal shell 21 and the outside air, and deterioration of the fluororesin layer 22 can be suppressed. In addition, the brick layer 24 has heat insulation similarly to the heat insulation layer 23, and can maintain the heat insulation layer 23, the fluororesin layer 22, and the metal shell 21 at low temperature. The brick layer 24 can improve heat insulation, so that thickness is increased.

  Since the bottom part 11, the side wall 12 and the discharge part 13 of the corrosion-resistant tank 1 have the laminated structure as described above, even if the content liquid in the corrosion-resistant tank 1 penetrates the brick layer 24 located inside the fluororesin layer 22 The fluorine resin layer 22 can suppress the content liquid from reaching the metal shell 21. Moreover, since the content liquid of the corrosion-resistant tank 1 cools in the process of permeating the brick layer 24, the corrosivity becomes weak. Therefore, the metal shell 21 is hardly corroded, and the corrosion resistance of the corrosion-resistant tank 1 can be increased.

  As shown in FIG. 3, the metal shell 21 constituting the side wall 12 has a flange portion 21a at the upper edge. The lid 111 is connected to the flange portion 21a. The fluororesin layer 22 constituting the side wall 12 extends to the flange portion 21a and covers the seating surface of the flange portion 21a. Thus, by covering the seating surface of the flange portion 21a with the fluororesin layer 22, corrosion of the flange portion 21a can be suppressed.

  As shown in FIG. 4, the metal shell 21 constituting the discharge portion 13 has a flange portion 21b at the tip. A flange 113 is connected to the discharge portion 13 via a flange portion 21b. The fluororesin layer 22 constituting the discharge portion 13 extends to the flange portion 21b and covers the seating surface of the flange portion 21b. Thus, by covering the seating surface of the flange portion 21b with the fluororesin layer 22, corrosion of the flange portion 21b can be suppressed.

  By the way, a crude nickel sulfate aqueous solution may be intermittently supplied to the electric evaporation tank 110. In this case, the discharge of the crude nickel sulfate aqueous solution from the flow path 14 is also intermittent. Since the period during which the heated crude nickel sulfate aqueous solution is discharged and the period during which it is not discharged are repeated, the discharge unit 13 is repeatedly heated and allowed to cool. Therefore, a load due to repeated thermal expansion and contraction is applied to the discharge unit 13, which causes the discharge unit 13 to deteriorate.

As shown in FIG. 1, in the corrosion-resistant tank 1 of the present embodiment, the thickness T ₁ of the brick layer 24 that constitutes the bottom portion 13 a of the discharge portion 13 is secured to the same level as the thickness T ₂ of the brick layer 24 of the side wall 12. Has been. Specifically, the thickness T ₁ is 0.5 to 1.5 times the thickness T ₂ . Thus, since the brick layer 24 of the discharge part 13 is comparatively thick, the discharge part 13 can endure the load by thermal expansion and thermal contraction.

  As described above, the corrosion-resistant tank 1 has high corrosion resistance, and the discharge unit 13 can withstand a load caused by thermal expansion and contraction. Therefore, the corrosion resistant tank 1 has a long service life. Therefore, the opportunity loss by the operation stop accompanying the update of the corrosion-resistant tank 1 and the cost concerning the update of the corrosion-resistant tank 1 can be reduced.

  In addition, the use of the corrosion-resistant tank 1 is not limited to the electric evaporation tank 110, but is suitably used as a tank for treating a highly corrosive liquid such as high temperature and high-concentration sulfuric acid.

Next, examples will be described.
The operation using the nickel removal equipment shown in FIG. 6 was performed. The copper removal electrolytic solution supplied to the electric evaporation tank 110 has a nickel concentration of 30 to 35 g / L, a copper concentration of 0.05 g / L or less, and an arsenic concentration of 1.0 g / L or less. The copper removal electrolyte was preheated to 90 ° C. and then supplied to the electric evaporation tank 110. The set value of the heating temperature of the electric evaporation tank 110 is 160 ° C.

Example 1
The corrosion resistant tank 1 shown in FIG. As shown in FIG. 2, the bottom part 11, the side wall 12, and the discharge part 13 are configured by laminating a metal shell 21, a fluororesin layer 22, a heat insulating layer 23, and a brick layer 24 in this order. The fluororesin layer 22 was formed by coating lining. As a result, the service life of the electric evaporation tank 110 was 5 years or more.

(Example 2)
The corrosion resistant tank 2 shown in FIG. 5 was used as the tank body of the electric evaporation tank 110. The configuration of the corrosion-resistant tank 2 is basically the same as that of the corrosion-resistant tank 1 shown in FIG. 1, but the thickness T ₁ of the brick layer 24 that forms the bottom of the discharge portion 13 is the same as that of the brick layer 24 on the side wall 12. 0.2 times the thickness T _2. The fluororesin layer 22 was formed by sheet lining. As a result, the service life of the electric evaporation tank 110 was about 2.5 years.

DESCRIPTION OF SYMBOLS 1 Corrosion-resistant tank 11 Bottom part 12 Side wall 13 Discharge part 14 Flow path 21 Metal shell 21a Flange part 21b Flange part 22 Fluororesin layer 23 Heat insulation layer 24 Brick layer

Claims (6)

The bottom,
A side wall erected on the periphery of the bottom,
The bottom and the sidewalls are each
A metal shell formed of metal,
A fluorine resin layer formed on the inner surface of the metal shell and formed of a fluorine resin;
A corrosion-resistant tank comprising: a brick layer which is located inside the fluororesin layer and formed of brick. The corrosion-resistant tank according to claim 1, wherein the fluororesin layer is formed by coating the metal shell with a fluororesin. The bottom and the sidewalls are each
The corrosion-resistant tank according to claim 1, further comprising a heat insulating layer positioned between the fluororesin layer and the brick layer. The metal shell of the side wall has a flange portion at an upper edge,
The corrosion-resistant tank according to claim 1, wherein the fluororesin layer on the side wall covers a seating surface of the flange portion. A discharge part protruding outward from the outer surface of the side wall and having a flow path for the content liquid;
The bottom of the discharge part is
A metal shell formed of metal,
A fluorine resin layer formed on a top surface of the metal shell and formed of a fluorine resin;
A brick layer located on the upper side of the fluororesin layer and formed of bricks,
The metal shell of the discharge part has a flange part at the tip,
The corrosion-resistant tank according to claim 1, wherein the fluororesin layer of the discharge part covers a seating surface of the flange part. A discharge part protruding outward from the outer surface of the side wall and having a flow path for the content liquid;
The bottom of the discharge part is
A metal shell formed of metal,
A fluorine resin layer formed on a top surface of the metal shell and formed of a fluorine resin;
A brick layer located on the upper side of the fluororesin layer and formed of bricks,
The thickness of the said brick layer which comprises the said bottom part of the said discharge part is 0.5-1.5 times the thickness of the said brick layer of the said side wall, The Claim 1, 2 or 3 characterized by the above-mentioned. Corrosion resistant tank.

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