JP4862182B2 - Zinc electrolytic refining method and supporting jig for zinc electrolytic refining - Google Patents

Description

  The present invention relates to a wet zinc electrolytic refining method in which a current is passed between an anode plate and a cathode plate disposed in a zinc electrolyte, and zinc is electrodeposited on the cathode plate.

  In zinc electrolytic refining, electricity costs account for the majority of the cost. For this reason, zinc electrolytic refining is carried out at night when the unit price of electricity is lower. In addition, in order to perform zinc refining in a short time, zinc is refined by high current with increased current density.

However, high current density makes it possible to collect zinc in a short time. On the other hand, high current density increases the temperature of the bus bar in electrical contact with the head bar of the anode and cathode plates. However, an oxide film is formed on the bus bar, and the head bar and the bus bar are damaged by heat. In order to solve this problem due to heat generation, Patent Document 1 enables a high current density of 500 A / m ² by watering the bus bar and cooling it.

JP-A-6-212472

Increasing the current density can shorten the time required for electrolytic refining and improve efficiency. For this reason, for example, it is desired to perform zinc electrolytic refining at a high current density of 600 A / m ² . However, when zinc electrolytic refining is performed at a high current density of 600 A / m ² or more, zinc is locally deposited on the cathode plate during electrolytic refining and makes electrical contact with the opposing anode plate, The possibility of causing a short circuit is increased. The electrolytic refining stops between the cathode plate and the anode plate where the short circuit occurs. Even if the current density is 600 A / m ² , the power is wasted due to the short circuit, and the electrolysis efficiency of the entire electrolytic cell is lowered.

An object of the present invention is to perform zinc electrolytic refining without causing a short circuit at a high current density of 600 A / m ² .

The inventors of the present invention have intensively studied to solve the above-mentioned problems. As a result, by arranging the gap between the anode plate and the cathode plate at equal intervals with a predetermined accuracy, almost no short circuit is caused at a high current density of 600 A / m ^2. It has been found that zinc electrolytic refining can be performed without any occurrence.

According to the present invention, a plurality of anode plates and cathode plates are alternately arranged in parallel substantially at predetermined intervals in the zinc electrolyte, and electricity is passed between the anode plate and the cathode plate through the zinc electrolyte. In the wet zinc electrolytic refining method in which zinc is electrodeposited on the cathode plate, the center interval between the anode plate and the cathode plate is set to 20 to 40 mm, and the standard deviation of the center interval is set to less than 4.1 mm, between the anode plate and the cathode plate. There is provided a zinc electrolytic refining method characterized by energizing at a current density of 600 A / m ² or more.

According to the present invention, there is also provided a support jig for supporting the head bar, which is disposed at the upper end of the electrolytic cell in which the zinc electrolyte is placed, and which is attached to the upper end of the anode plate and the cathode plate. And a plurality of passage portions through which the head bar passes are alternately arranged in series, and the support portion is disposed in front of and behind the plane portion in the longitudinal direction of the plane portion and the support jig, and gradually increases as the distance from the plane portion increases. When the end portion of the head bar is placed on the upper surface of the support portion, the head bar slides down the slope with its own weight, and the plane A support jig for zinc electrolytic refining is provided, in which the head bar is positioned by moving to a portion .

By setting the interval between the plurality of anode plates and cathode plates alternately arranged in parallel in the zinc electrolyte to a center interval of 20 to 40 mm and a standard deviation of the center interval of less than 4.1, 600 A / m ^With a high current density of ² , zinc electrolytic refining can be performed with almost no short circuit. According to the present invention, the occurrence of a short circuit can be reduced by about 30% or more, and the current efficiency can be improved by 1.3%, thereby improving the productivity of zinc electrolytic refining.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of the electrolytic cell 1. FIG. 2 is a front view of the anode plate 2 (cathode plate 3). FIG. 3 is a perspective view of the support jigs 11 and 12. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

A zinc electrolytic solution 10 is placed in a rectangular parallelepiped electrolytic cell 1 whose upper surface is open. The zinc electrolyte 10 is mainly composed of zinc sulfate, and additionally contains manganese and the like. Although the components are not always constant, for example, main components of the electrolyte before electrolysis are 155 to 175 g / L for zinc, Cd <0.1 ppm, Cu <0.1 ppm, Fe, Co, nickel, arsenic, Contains antimony, manganese, magnesium, sulfuric acid, etc. After electrolysis, it becomes zinc 60-70 g / L, free sulfuric acid 150-190 g / L , manganese 2.5-4.5 g / L, and magnesium oxide <19 g / L. Although not shown, piping for introducing and discharging the zinc electrolyte 10 is connected to the electrolytic cell 1.

  Support jigs 11 and 12 are placed in pairs on the left and right upper ends of the electrolytic cell 1. Further, bus bars 13 and 14 for energization are arranged in pairs on the left and right outer sides of the electrolytic cell 1 (the outer sides of the support jigs 11 and 12). One of the bus bars 13 and 14 is a positive electrode (anode), and the other is a negative electrode (cathode). Hereinafter, as an example, the left bus bar 13 will be described as an anode, and the right bus bar 14 will be described as a cathode.

As shown in FIG. 2A, both the anode plate 2 and the cathode plate 3 have a substantially T-shape with a head bar 21 for energization and load support attached to the upper edge of the electrode plate 20. ing. The electrode plate 20 is formed in a substantially rectangular thin plate shape. The material of the electrode plate 20 is lead in the case of the anode plate 2, and is made of, for example, lead - 0.85 mass% silver alloy and has an area of about 1.7 m ² . It is also possible to use other alloy compositions for the electrode plate 20 of the anode plate 2. For example, a lead - silver-calcium alloy can be used. Pb - compared to 1.0% Ag-cast anode, pb - the effect of lowering the 0.5% Ag -0.4% Ca-cast using the anode when the cell voltage. In the case of the cathode plate 3, for example, aluminum or an alloy thereof is used, and the area is about 1.7 m ² . Moreover, you may use metals with strong acidity, such as titanium. The head bar 21 is a copper rod or the like.

  The left and right end portions of the head bar 21 protrude outward in the left and right directions at the upper edge of the electrode plate 20. The thickness t (shown in FIG. 2B) of the head bar 21 is t = 17 mm for the anode plate 2 and t = 15 mm for the cathode plate 3. In plan view as shown in FIG. 2, the central axis in the length direction of the head bar 21 and the central axis in the width direction of the electrode plate 20 substantially coincide with each other, and the entire front and back surfaces of the electrode plate 20 are center lines of the head bar 21. It is formed so that it may become parallel to. This is because the position of the electrode plate 20 can be accurately grasped by the head bar 21 and the electrode plates 20 are arranged in parallel in the electrolytic cell 1.

  As shown in FIG. 3, each of the support jigs 11 and 12 has a plurality of support portions 26 supporting the head bar 21 on the upper surface of the long plate-shaped base portion 25 along the longitudinal direction. It is the configuration arranged. A gap formed between the support portions 26 on the upper surface of the base portion 25 serves as a passage portion 27 through which the head bar 21 passes, and the support portion 26 extends along the longitudinal direction on the upper surface of the base portion 25. And a plurality of passage portions 27 are alternately provided in series.

  A guide recess 30 is formed on the upper surface of each support portion 26 to guide the head bar 21 so that the end of the head bar 21 is held in a posture orthogonal to the longitudinal direction of the base portion 25. The guide recess 30 includes a flat portion 31 and a pair of inclined surfaces 32 and 32 disposed in front and rear of the flat portion 31 (front and rear in the longitudinal direction of the base portion 25). The inclined surfaces 32 and 32 are formed so as to gradually increase as the distance from the flat surface portion 31 increases before and after the flat surface portion 31.

  The width s of the flat portion 31 (the width s in the longitudinal direction of the base portion 25) is the same as that of the left support jig 11 on which the head bar 21 (thickness t = 15 mm) of the cathode plate 3 is placed on the support portion 26 as will be described later. In that case, s = 19 mm. Further, as described later, in the right support jig 12 on which the head bar 21 (thickness t = 17 mm) of the anode plate 2 is placed on the support portion 26, s = 21 mm.

  As described later, the guide concave portion 30 including the central flat portion 31 and the pair of inclined surfaces 32 and 32 disposed on the front and rear sides thereof is formed on the upper surface of the support portion 26. When the end of the head bar 21 is placed on the upper surface of the head 26, the head bar 21 slides down on the slopes 32, 32 by its own weight and inevitably moves to the lowermost flat surface portion 31. Thus, the head bar 21 is positioned substantially at the center of the upper surface of the support portion 26.

  Further, a vertical wall portion 35 for pressing the end surface of the head bar 21 is provided on the outer edge of the upper surface of the support portion 26 so as to protrude upward. Since the vertical wall portion 35 is formed on the outer edge of the upper surface of the support portion 26, as described later, when the end portion of the head bar 21 is placed on the upper surface of the support portion 26, the end surface of the head bar 21. Is held by the inner surface of the vertical wall 35 so that the end of the head bar 21 does not protrude outward from the support jigs 11 and 12.

  The passage portion 27 formed between the support portions 26 has a sufficient width s ′ for allowing the head bar 21 to pass therethrough. The width s ′ of each passage portion 27 (the width s ′ in the longitudinal direction of the base portion 25) corresponds to that of the left support jig 11 through which the head bar 21 (thickness t = 17 mm) of the anode plate 2 passes, as will be described later. In this case, s ′ = 24 mm. As will be described later, in the right support jig 12 through which the head bar 21 (thickness t = 15 mm) of the cathode plate 3 passes, s ′ = 19 mm.

  Each passing portion 27 does not have the above-described vertical wall portion 31 formed on the outer edge of the upper surface of the support portion 26. For this reason, as will be described later, when the end of the head bar 21 is inserted into the passage portion 27, the end of the head bar 21 may be projected outward from the support jigs 11 and 12. Is possible.

  The support portions 26 and the passage portions 27 are alternately arranged at substantially equal intervals along the longitudinal direction of the base portion 25. That is, the distance L between the center axis 26 ′ of the support portion 26 and the center axis 27 ′ of the passage portion 27 in the adjacent support portion 26 and the passage portion 27 (center distance L between the adjacent support portion 26 and the passage portion 27). Both are set equal. In this case, the length of each center interval L is 32 mm for both the support jigs 11 and 12. Thereby, in both of the support jigs 11 and 12, the pitch interval between the support portions 26 and the pitch interval between the passage portions 27 are 64 mm. In this case, in both the support jigs 11 and 12, the dimensional error between the pitch interval between the support portions 26 and the pitch interval between the passage portions 27 is set to be ± 0.5 mm or less.

  The entire support jigs 11 and 12 are integrally formed of an insulating material such as a resin having heat resistance and acid resistance. These support jigs 11 and 12 are preferably formed as hollow ribs to reduce the cost of the resin raw material and to strengthen the strength.

  In order to perform zinc electrolytic refining, first, the base portions 25 of the support jigs 11 and 12 are placed on the left and right upper ends of the electrolytic cell 1 in which the zinc electrolyte 10 is put, and the left and right support jigs 11 and 12 are attached. Place them in pairs. In this case, the left support jig 11 is arranged so that the vertical wall portion 31 on the upper surface of the support portion 26 is outside the electrolytic cell 1, and the right support jig 12 is provided with the support portion 26. It arrange | positions so that the vertical wall part 31 of an upper surface may become the outer side of the electrolytic cell 1. FIG.

  Further, the left and right support jigs 11 and 12 are arranged so as to be shifted from each other by a length equal to the center distance L between the adjacent support portions 26 and the passage portions 27 along the longitudinal direction of the left and right upper ends of the electrolytic cell 1. As described above, the left and right support jigs 11 and 12 have the center distance L between the adjacent support portions 26 and the passage portions 27 equal to about 32 mm. 12 are shifted from each other by the center distance L, so that the passing portion 27 of the right support jig 12 is positioned in front of each support portion 26 of the left support jig 11, and the right support jig 12 The left and right support jigs 11 and 12 are arranged to face each other so that the passage part 27 of the left support jig 11 is positioned in front of each support part 26.

  A plurality of (for example, 48 to 59) anode plates 2 and cathode plates 3 are mounted on the left and right support jigs 11 and 12 across the head bar 21 of the anode plate 2 and the cathode plate 3. Are alternately inserted into the electrolytic cell 1. The anode plate 2 and the cathode plate 3 can be inserted while the anode plate 2 and the cathode plate 3 are lowered from above the electrolytic cell 1 by a crane or the like. At that time, when placing the anode plate 2, as shown in FIG. 4, the right end portion of the head bar 21 is placed on the support portion 26 of the right support jig 12 placed on the upper right end of the electrolytic cell 1. The left end portion of the bar 21 is passed through the passage portion 27 of the left support jig 11 placed on the upper left end of the electrolytic cell 1 (the passage portion 27 facing the support portion 26 on which the right end portion of the head bar 21 is placed). . When the right end portion of the head bar 21 of the anode plate 2 is placed on the support portion 26 of the right support jig 12, the right end surface of the head bar 21 is pushed against the inner surface of the vertical wall portion 31 on the upper surface of the support portion 26. In this manner, the left and right positions of the anode plate 2 can be easily positioned. Then, the left end portion of the head bar 21 of the anode plate 2 positioned in this way passes through the passage portion 27 of the left support jig 11 to the outside of the left support jig 11 (further than the support jig 11). It protrudes to the left side) and comes into electrical contact with the anode bus bar 13 disposed on the left outer side of the electrolytic cell 1 (outside the support jig 11). Since the right end portion of the head bar 21 of the anode plate 2 is placed on the upper surface of the support portion 26, the cathode bus bar 14 disposed on the right outer side of the electrolytic cell 1 (outside the support jig 12) is electrically connected. Do not touch.

  Further, by placing the right end portion of the head bar 21 of the anode plate 2 on the support portion 26 of the right support jig 12, the right end portion of the head bar 21 is positioned back and forth by the guide recess 30 on the upper surface of the support portion 26. Similarly, by passing the left end portion of the head bar 21 of the anode plate 2 through the passage portion 27 of the left support jig 11, the left end portion of the head bar 21 is positioned back and forth by the passage portion 27. Thus, the anode plate 2 is inserted into the electrolytic cell 1 in a state where the front, rear, left and right positions are accurately positioned, and the electrode plate 20 of the anode plate 2 is contained in the zinc electrolyte 10 placed in the electrolytic cell 1. It will be in the state immersed in.

  On the other hand, when the cathode plate 3 is placed on the left and right support jigs 11, 12, the left support jig 11 with the left end portion of the head bar 21 placed on the upper left end of the electrolytic cell 1, as shown in FIG. 5. The right end portion of the head bar 21 is placed on the upper right end of the electrolytic cell 1 and the passage portion 27 of the right support jig 12 (opposite to the support portion 26 on which the left end portion of the head bar 21 is placed). Through the passing section 27). Similarly, when the left end portion of the head bar 21 of the cathode plate 3 is placed on the support portion 26 of the left support jig 11, the left end surface of the head bar 21 is placed inside the vertical wall portion 31 on the upper surface of the support portion 26. The left and right positions of the cathode plate 3 can be easily positioned by pressing against the side surfaces. Then, the right end portion of the head bar 21 of the cathode plate 3 positioned in this way passes through the passage portion 27 of the right support jig 12 to the outside of the right support jig 12 (further than the support jig 12). It protrudes to the right side) and comes into electrical contact with the cathode bus bar 14 disposed on the right outside of the electrolytic cell 1 (outside the support jig 12). Since the left end portion of the head bar 21 of the cathode plate 3 is placed on the upper surface of the support portion 26, the anode bus bar 13 disposed on the left outer side of the electrolytic cell 1 (left side of the support jig 11) is electrically connected. Do not touch.

  Further, by placing the left end portion of the head bar 21 of the cathode plate 3 on the support portion 26 of the left support jig 11, the left end portion of the head bar 21 is positioned back and forth by the guide recess 30 on the upper surface of the support portion 26. Similarly, by passing the right end portion of the head bar 21 of the cathode plate 3 through the passage portion 27 of the right support jig 12, the right end portion of the head bar 21 is positioned back and forth by the passage portion 27. Thus, the cathode plate 3 is inserted into the electrolytic cell 1 in a state where the front, rear, left and right positions are accurately positioned. It will be in the state immersed in.

  Thus, by placing a predetermined number of anode plates 2 and cathode plates 3 on the left and right support jigs 11 and 12, a plurality of anode plates 2 and cathode plates 3 are provided in the electrolytic cell 1 with a predetermined number. It becomes the state arrange | positioned alternately at intervals and substantially parallel. As described above, the central axis in the length direction of the head bar 21 and the central axis in the width direction of the electrode plate 20 substantially coincide, and the entire front and back surfaces of the electrode plate 20 are parallel to the center line of the head bar 21. It is formed to become. For this reason, by aligning the anode plate 2 and the cathode plate 3 with the head bar 21, the electrode plate 20 of the anode plate 2 and the electrode plate 20 of the cathode plate 3 can be arranged substantially parallel to each other. In this case, as described above, the thickness t of the head bar 21 of the anode plate 2 is set to 17 mm, the thickness t of the head bar 21 of the cathode plate 3 is set to 15 mm, and the upper surface of the support portion 26 of the left support jig 11 is set. The width s of the flat portion 31 of the guide recess 30 formed on the right side is set to 19 mm, and the width s of the flat portion 31 of the guide recess 30 formed on the upper surface of the support portion 26 of the right support jig 12 is set to 21 mm. The width s ′ of the passage portion 27 of the support jig 11 is set to 24 mm, and the width s ′ of the passage portion 27 of the right support jig 12 is set to 19 mm. Therefore, by positioning the head bars 21 of the anode plate 2 and the cathode plate 3 on the left and right support jigs 11 and 12 in this way, the plurality of anode plates 2 and the cathode plates 3 are mutually connected. Between the adjacent anode plate 2 and cathode plate 3, the center distance between them is substantially equal to the center distance L = 32 mm between the support portions 26 and the passage portions 27 of the support jigs 11 and 12. Further, the variation in the center distance between the anode plate 2 and the cathode plate 3 adjacent to each other is 0.22 mm or less, and the standard deviation is less than 4.1 mm. It should be noted that the distance or variation between the electrode plate 20 of the anode plate 2 and the electrode plate 20 of the cathode plate 3 can be measured alternatively by the position of the head bar 21 of the anode plate 2 and the cathode plate 3.

In this way, a plurality of anode plates 2 and cathode plates 3 are alternately arranged in parallel in the electrolytic cell 1 at predetermined intervals, and a positive charge is applied to the left bus bar 13, and the right bus bar 14 By applying a negative charge to the anode plate 2, electricity is passed between the anode plate 2 and the cathode plate 3, and electrolytic zinc is electrodeposited on the cathode plate 3. In this case, the voltage applied between the bus bars 13 and 14 is adjusted so that current flows between the anode plate 2 and the cathode plate 3 at a current density of 600 A / m ² or more. In this case, an SCR may be used as the rectifier.

According to the above embodiment, the center interval between the plurality of anode plates 2 and cathode plates 3 alternately arranged in parallel in the zinc electrolyte 10 is 20 to 40 mm, and the standard deviation of the center interval is 4.1. Therefore, zinc electrolytic refining can be performed with almost no short circuit even at a high current density of 600 A / m ² . Since the anode plate 2 is a plate made of lead, there is a warp and bend of about 1 mm. However, improvement in the accuracy of the position interval of the cathode plate 3 contributes to prevention of short circuit and improvement in electrolytic efficiency, and stable operation is possible even at a high current density of 600 A / m ² or more. Note that it is generally said that the cell voltage decreases when the distance between the electrodes is small, and it is desirable to shorten the distance between the electrodes.

  Although an example of the embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. For example, in the support jigs 11 and 12 described with reference to FIG. 3, the example in which the vertical wall portion 35 for pressing the end surface of the head bar 21 is provided on the outer edge of the upper surface of the support portion 26 that supports the head bar 21 has been described. However, for example, as shown in FIG. 6, a support portion 26 that does not have the vertical wall portion 35 on the upper surface may be used. In this case, both the left and right support jigs 11 and 12 may have a configuration in which the vertical wall 35 is not provided on the upper surface of the support part 26. For example, the left support jig on which the head bar 21 of the cathode plate 3 is placed. 11, the vertical wall portion 35 is not provided on the upper surface of the support portion 26, and the vertical wall portion 35 is provided on the upper surface of the support portion 26 in the right support jig 11 on which the head bar 21 of the anode plate 2 is placed. good. Conversely, in the left support jig 11 on which the head bar 21 of the cathode plate 3 is placed, the vertical wall 35 is provided on the upper surface of the support portion 26, and in the right support jig 11 on which the head bar 21 of the anode plate 2 is placed. The vertical wall portion 35 may not be provided on the upper surface of the support portion 26.

Zinc electrolytic refining was performed under the conditions described in FIGS. As a comparative example, the anode plate 2 and the cathode plate 3 are connected to the electrolytic cell by using a jig in which the width s ′ of the passage portion 27 that allows the head bar 21 (thickness t = 15 mm) of the cathode plate 3 to pass is 30 mm. 1 was inserted. In the comparative example, the average variation in the distance between the electrodes was 3.1 mm, and the standard deviation was 4.1. In the zinc electrolytic refining according to the example of the present invention under the conditions described in FIGS. 1 to 5, the current efficiency was improved by 1.25% and the short-circuit rate of the electrode was improved by 30% or more as compared with the comparative example. If the electrolytic efficiency is improved by 1%, the annual cost will be reduced by several tens of millions of yen. The current density is limited by the ability of the rectifier and the electrolyte composition, but excluding those restrictions, it can be 600-800 A / m ² or more, especially stable by the current density at 700-800 A / m ^2. This operation is possible with the present invention.

  The present invention can be used for wet zinc electrolytic refining.

It is a top view of an electrolytic cell. It is a front view of an anode plate (cathode plate). It is a perspective view of a support jig. It is explanatory drawing of the state which inserts an anode plate in an electrolytic cell. It is explanatory drawing of the state which inserts the cathode plate 3 in an electrolytic cell. It is a perspective view of the support jig which does not provide a vertical wall part on the upper surface of a support part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolysis tank 2 Anode plate 3 Cathode plate 11,12 Support jig 10 Zinc electrolyte solution 13,14 Bus bar 20 Electrode plate 21 Head bar 25 Base part 26 Support part 27 Passing part 30 Guide recessed part 31 Plane part 32 Slope 35 Vertical wall part

Claims (2)

A plurality of anode plates and cathode plates are alternately arranged in parallel in the zinc electrolyte at a predetermined interval, energized between the anode plate and the cathode plate through the zinc electrolyte, and zinc is supplied to the cathode plate. In the wet zinc electrolytic refining method,
The center gap between the anode plate and the cathode plate is set to 20 to 40 mm, and the standard deviation of the center interval is set to less than 4.1, and current is passed between the anode plate and the cathode plate at a current density of 600 A / m ² or more. , Zinc electrolytic refining method. A support jig for supporting a head bar disposed at the upper end of an electrolytic cell in which a zinc electrolyte is placed and attached to the upper end of an anode plate and a cathode plate,
A plurality of support portions for supporting the head bar and a plurality of passage portions for passing the head bar are alternately provided in series .
The support part has a guide recess composed of a flat part and a pair of inclined surfaces which are arranged in front and back of the flat part in the longitudinal direction of the support jig and are formed so as to gradually increase as the distance from the flat part increases. When the end of the head bar is placed on the upper surface of the support part, the head bar slides down on the slope due to its own weight and moves to the flat part, and the head bar is positioned. , Support jig for zinc electrolytic refining.

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