JPS5919994B2 - Method for producing metal powder from dilute solution of metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to metals, and in particular to the recovery or extraction of metals in powdered form by electrolytic means.

The production of metal powders by electrolytic means is well known.

For example, in 1960, McGrawHillBooKCo
Written by C. L. Mantel, published by mpany”E
electrochemical engineering
) 4th edition''. In fact, the cathode current density when producing powders is higher than the cathode current density when scouring metals into bulk cathodes (IOOA/7
7! '60OA/7-! ■), and the metal concentration in powder production is lower than in smelting (approximately 409/
5θ/l). The metal is electrodeposited on the cathode as separate particles and collected at the bottom of the electrolytic cell, ie, as a loosely attached electrodeposit, the cathode is lifted from the electrolytic cell and the electrodeposit is washed off the cathode. Some methods and apparatus electrodeposit metal powder onto a movable or continuous cathode.

For example, US Pat. No. 1,736,857 discloses and claims an apparatus comprising an endless cathode in the form of a band that passes continuously between anodes in a bath containing an electrolyte. U.S. Patent 2,810,68
No. 2 discloses and claims a method for producing silver powder from soluble silver anodes. The anode is dissolved in an electrolyte and formed on a disk-shaped cathode whose powder is slowly rotating through the electrolyte. The electrodeposited powder is deposited on the rotating cathode surface with a pair of metal doctor blades.
orblade). This powder settles to the bottom of the electrolytic cell and is periodically recovered by draining the electrolyte. U.S. Pat. No. 1,959,376 describes a method for producing copper powder, and U.S. Pat. No. 2,053,2
No. 22 discloses the device. According to these patents, a series of disk-shaped copper cathodes are mounted within an electrolytic cell such that each cathode is partially immersed within the cell. A soluble copper anode is suspended on each side of each cathode within the electrolytic cell. The cathode rotates when current is passed between the electrodes. The copper electrodeposited on the surface of the rotating cathode is removed as a powder by a doctor blade mounted above the surface of the electrolyte. U.S. Pat. No. 3,616,277 discloses a method and apparatus for producing copper powder. Metal powders, such as copper powders, are electrodeposited onto a series of disc-shaped cathodes while they are circulated through a metal electrolyte solution. These cathodes are preferably made of titanium;
It is partially immersed in the electrolyte in the electrolytic tank. The insoluble anode is preferably made of platinum-plated titanium and is placed between the cathodes in the cell. The powder is continuously electrodeposited onto the cathode and continuously removed by a doctor blade (preferably made of plastic and mounted adjacent to the cathode above the electrolyte level of the cell).

Electrolytic cells using rotating cylindrical electrodes are well-known and well-studied devices.

For example 6TheJ0urna10fAppIiedE1
ectr0chemistry11974, Volume 4,
See the article by D. R. Gabe on page 91 and the references cited therein. This rotating cylindrical electrode bath is used for metal electrodeposition and has been extensively studied. Many studies have shown that rotating It has been confirmed that the current density that can be achieved with a cylindrical electrode is controlled by the following equation (in which 1
= current density, A/Cd. n = valence change, F = 96,500 coulombs, C = molar concentration of metal ions per d, V = peripheral velocity of the cylindrical electrode, d = diameter of the cylindrical electrode, u = kinematic viscosity of the solution, D = The diffusion coefficient of metal ions, p=exponent), where K is a constant and x=1+p, where x was found to be approximately 0.66 by the aforementioned study.

The above simplified formula is as follows: (10 in the formula is the current (4) actually used to produce metal powder in the tank;
10 is the current density 1 (A/(7
It can also be written as L) multiplied by the electrode area.

IO is actually the total current in the bath times the current efficiency for metal electrodeposition. To the best of our knowledge, no proposals have been made to use rotating cylindrical electrode electrolysers for the production of metal powders;
, 277, as it has the advantage of being continuous.

However, surprisingly, equation 1KC0
Instead of the ultimate current density for metal powder production in an electrolytic cell defined by This means that the ultimate current density is almost directly proportional to the peripheral speed of the rotating electrode. This also means that the throughput of such equipment is significantly increased, or that the desired concentration of metal in the solution for producing metal powder at a set current density is greatly reduced. Therefore, the electrolytic cell described in Example 1 below has a total ultimate current defined by Equation 10 = 4.38 x 104CVX. Peripheral speed 6V゛ is 1
00c! RL/Sec and the copper concentration is 200
ppm, the total ultimate current 410' is 9.7 A (ampere), assuming 6x1 is 0.66. In contrast, in the present invention, "X" in Example 1 is equal to 0.92. Therefore, the total ultimate current IOl is 504A.
That is, it increases by 52 times. In order to maintain a high current of 504 A, a method based on the known properties of a rotating cylinder operates at a copper concentration of 10400 ppm, or 52 times higher;
Alternatively, it must be rotated at a peripheral speed of 398100 cWL/Sec, that is, approximately 398 times the speed in the present invention.

Under the conditions described in the method based on the known properties of the rotating cylinder, the electrolytic cell has a production capacity of only 11.59/hour, whereas with the present invention a production capacity of 6009/hour can be expected. Similarly, using an electrolytic cell as described in Example 1, if the copper concentration 6C' is maintained at 200 ppm and the peripheral velocity 'V' is reduced to 500 cTn/Sec, the following results. According to the method based on the known properties of a rotating cylinder, if "x" is 0.66, the ultimate metal deposition current "IOl6A" is 79% of copper powder per hour.
generate. On the other hand, if the present invention is used, and "x" is 0.92, the electrolytic cell current will be 266 A, and 316 g of copper powder will be produced per hour. This amount of production is 43% of the amount produced by a method based on the known characteristics of a rotating cylinder.
reach double. In order to maintain such high currents and production rates in a method based on the known properties of rotating cylinders, the copper concentration must be increased to 8682 ppm, or the peripheral velocity must be increased to 151400 c7n/Secl, i.e.
The speed must be increased to about 303 times the speed of the present invention. On the other hand, "x" is 1.1 and "C" is 200ppm."
If V゛ is 1000CfL/Sec and the current efficiency is 72%, the actual current value that must be applied is 2426.
A, which makes it impractical. Therefore, the value of 6x'' that meets practical operating conditions is between 0.7 and 1.0. The method of implementing the invention is not completely understood. The metal particles are deposited on the rotating cylinder. , many of these precipitated particles are immediately removed. Therefore, the surface is not fixed and can be regenerated over time. New surfaces are continuously generated. The surface is somewhat uneven, and
Its surface area is larger than that of the rotating cylinder. Therefore,
The actual size, roughness, and surface area of the rotating cylinder on which the metal powder is deposited cannot be specified. The fact that size, roughness, surface area, etc. cannot be specified explains why accepted laws do not apply. It has also been discovered that it is beneficial to roughen the surface of the cathode, for example by etching, before the metal is deposited on the surface of the cathode. Roughening the cathode surface beforehand ensures a large amount of migration into the electrolytic cell;
The valence of x increases. Therefore, according to the present invention, the method for producing metal powder from a dilute aqueous solution of metal is based on a rotating cylindrical cathode l-ray 71)
? It consists of operating a rotating cylindrical cathode cell with a current density that is a function of the solution concentration with respect to L'f and the peripheral velocity of the cathode.

Accordingly, the present invention provides an electrolytic method for producing metal powder by electrolyzing a dilute aqueous solution of a metal in an electrolytic cell having a rotating cylindrical cathode.

The peripheral speed of the rotating cylindrical cathode as well as the current density of the cathode can be selected in relation to the concentration of metal ions such that powder deposits are produced. Also, the metal powder can be removed from the cathode during rotation of the cathode and can be continuously drained from the electrolytic cell. The dilute aqueous solution electrolyzed by the method of this invention may contain 2 to 10,000 ppm metal ions. Generally, the method of this invention is carried out according to the following formula.

Here, x = 0.7 to 1.0, preferably 0.8 to 0.95: I, K, C and are as defined above, and have values in the operable range and preferred range as below. :Current density 1 operable value - -1''?''▼ - Ai-' The peripheral speed of the rotating cylindrical electrode, K, is a constant and is for a specific electrolytic cell, so the operable value is also a suitable value. cannot be limited either.

From (Vd)P in the above equation (1), equation 1 = KCVX is oversimplified, and although K cannot be an absolute constant, it depends to some extent on the value of p, and therefore depends on the value of x. It will be recognized that

The value of K depends not only on the metal being deposited, but also on the temperature and the geometry of the cell, ranging from 5 x 104 to 5 x 1
04 range; KO varies accordingly. In organic electrochemistry, organic materials can be decomposed with a pair of electrodes.

For example, products formed at the cathode by cathodic reduction are oxidized and decomposed at the anode. In this case, it is common to use a septum between the electrodes, thereby separating the cathode and anode compartments (M.J. Allen, Organic E.
IectrOchemistry,Chapman&H
alI, 1954). A variety of materials have been used as partitions to conduct electrical current but retain organic materials in either required compartment, such as parchment, asbestos cloth, other fabrics, and ion exchange membranes. This ion exchange membrane is a membrane containing an ion exchange membrane, such as an ion exchange membrane commonly used for electrodialysis.

The invention further includes embodiments in which the method is carried out in an electrolytic cell having a diaphragm, such as an ion exchange diaphragm, located between the rotating cathode and the anode or anode of the electrolytic cell.

The invention further includes an electrolytic cell comprising a rotating cylinder cathode in a compartment separated by a substantially concentric anode and means for supplying liquid to and removing liquid from the partitioned compartment.

The delimited cathode compartments are formed by more or less concentric anodes or anode compartments. Typically, the area of the rotating cylindrical cathode ranges from 200 cTi1 to 5,900 C171, but may be larger. The invention also includes embodiments for decomposing metal powders produced from other materials contained in the electrolytic cell.

This separation can be carried out by fairly simple physical means such as settling wet cyclone separation or other simple liquid/solid separations. Chemical means can also be used, for example by eluting or dissolving the metal in a suitable solvent such as a mineral acid or alkali to create a concentrated solution of the metal that is still attached to the cathode. It can be used to remove deposited metals. Electrochemical means, such as anodic dissolution, can also be used to redissolve the metal deposited on the cathode. Examples of metals that can be recovered by the method of this invention are chromium and manganese.

Iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, silver, cadmium, indium, tin,
These are iridium, platinum, gold, lead, uranium and rare earth metals. The metal mixture can be co-precipitated on the cathode of the electrolytic cell or with metalloids such as arsenic and antimony. The metalloids can be deposited on their own or in mixtures.
An important feature of the method of the invention is that the metal is produced in powder form, which can be easily removed from the electrolytic cell.

The method of the invention can be carried out in a number of electrolytic cells in series.

Alternatively, the method can be carried out during electrolysis in an electrolysis cell with a cathode compartment divided into a number of successive subcompartments, the aqueous solution of metal flowing through the subcompartments, While the solution passes through the aqueous solution, the concentration of metal ions in the aqueous solution gradually decreases. Preferably there are 6 to 10 subcompartments. This type of cell can itself be used as one cell in a series to further reduce metal ion concentrations in the effluent from previous cells. The invention also includes control of the working electrode potential, which is accomplished by known techniques.

This is important for best results with zinc electrodeposition, but less so with copper electrodeposition. Preferred means for controlling the electrolytic sliding voltage or electrode voltage are a voltage controller or a potential variable device. A voltage controller can be used to control the sliding voltage, and a potential variable device can be used to control the electrode voltage. Control of the pH of the electrolyte is also preferred in the case of zinc (details will be described later), and a pH range of 4 to 7 is preferred.

The electrolytic cell can be supplied with any form of current, such as direct current, alternating current, direct current pulse waves, or a superimposed wave thereof,
The sliding voltage can be controlled or the electrode voltage can be controlled using a reference electrode.
It can operate in the 20 volt range, but higher or lower pressures can also be used.

The operating time of the electrolytic cell is not particularly limited.

However, the operating temperature of the vessel is important to obtain the highest yield. As the aqueous electrolyte temperature increases, the total mass transferred to the cathode increases. Generally operating temperature is O to 100℃
however, it is preferred to use an operating temperature in the range of 20 to 80°C. The optimum operating temperature is about 60°C. The electrolyte used in the method of this invention is any water-soluble, electrically conductive salt of the metal being produced.

In the case of copper or zinc, it is a sulfate. Other electrolytes may also be present. The rotating cylindrical cathode of the electrolytic cell used in the process of the invention is generally made of any suitable metal, but it is preferred to use a copper cathode coated with a suitable coating, eg, an electrodeposited metal layer.

Therefore, a copper-coated steel cathode is used for copper electrodeposition, and a zinc-coated steel cathode is used for the zinc electrode. The anode of the electrolytic cell is preferably made of a relatively corrosion resistant metal such as a noble metal such as platinum, although lower cost metals such as lead may also be used. Another form of anode that can be used is valve metal coated with a precious metal. Suitable valve metals are titanium, zirconium, tantalum, and hafnium, any of which can be coated with platinum. The present invention provides an inexpensive continuous electrolysis device and method that can recover metals from dilute solutions.

Dilute solutions of metals (about 2 to about 10,000 ppm) can be efficiently processed, but economics is concentration dependent. Concentrated solutions can also be processed by diluting with cell effluent to bring the cell concentration within the appropriate concentration range (e.g., 200-300 ppm). Because the electrolyzer is dialysed, even highly contaminated solutions, such as those containing organics and other anode-damaging components, can be treated. Generally, the metal obtained by this invention is of high purity. In particular, metal obtained by electrodeposition of copper on a rotating cylindrical electrode is much more pure than metal obtained by cementation from a dilute solution, ie, by reduction of the solution with iron to deposit copper. The invention is therefore particularly advantageous in mine wastewater applications. The following are known to contain particularly low concentrations of metals:

a) Copper phthalocyanine factory effluents, b) Viscose factory effluents, c) Mine wastewaters, such as leachate wastes and other mineral waters, d
) tank discharge streams from conventional electrowinning processes; e) electroplating wash waters, e.g. galvanizing wash waters (particularly for strip steel and wire); f) pickling liquids during the production of copper and brass wire; g) The following waste materials, such as sewage sludge, can be processed to produce dilute solutions of various concentrations for use in this invention.

1. Chemical effluents: These include a) copper effluents 1) etching agents; l) catalysts in chemical production 111) pickling solutions b) chromium effluents 1) plating solutions 11) plating factory sludge 111) dichromium Sludge and solutions from acid oxidation c) Nickel waste 1) Metsuki waste and Metsuki factory sludge; i) Electrochemical cutting sludge d) Tin waste Metsuki solution and Metsuki factory sludge e) Zinc waste from organic chemical production such as zinc Solid waste products are obtained as ([) slag of zinc, brass, tin, etc., (il) cutting waste, 011) scrap of printed circuit boards (copper and precious metals), etc.

The electrolytic process of this invention is particularly applicable to the recovery of metallic zinc from viscose rayon factory effluents.

Viscose rayon is manufactured by spinning viscose (a caustic soda solution of cellulose xanthate) into sulfuric acid (F.D. Lewy, The Chemistry and Technology of Rayon Manufacture). 1961).

The use of zinc salts in the production of viscose rayon is well known.

Such zinc salts are used worldwide in acid spinning and drawing baths. The regenerated cellulose rayon produced in this manner contains a large amount of zinc, which is removed by washing, the washing liquid being one of the sources of the effluent. Acid spinning bath waste and drawing bath waste are also sources of effluent. These effluents contain sulfuric acid, sodium sulfate, magnesium sulfate, carbohydrates (e.g. glucose and other sugars, cellulose degradation products, etc.), sulfides, xanthates, surfactants (e.g. quaternary ammonium salts, e.g. : cetylpyridinium bromide) and zinc sulfate.

Treatment of these effluents is generally carried out in two ways:

(a) A method for recovering a zinc sulfate solution from the effluent of an acid spinning bath and a drawing bath by recrystallizing excess sodium sulfate and recycling the mother liquor for reuse. There is still a loss of zinc and other liquid waste due to the accumulation of impurities).

(b) Chemically treating the dilute wash liquor and waste liquor described above with ferrous sulfate to precipitate the sulfides, and treating the effluent with lime to neutralize and precipitate the zinc as a basic carbonate. How to do it.

The electrolytic method of the present invention described above has been found to be effective in recovering zinc from viscose rayon factory effluent.

The yield of zinc is improved if the acidity of the viscose effluent to be electrolyzed is low (eg PH 4-7).

Since the viscose effluent usually has a high acidity (e.g. PHL), the ... value of the effluent can be adjusted to a lower acidity value to avoid a low yield of zinc. Although the PH value may be adjusted before electrolysis, in non-diaphragm electrolytic cells, the PH value tends to drop during electrolysis. Although it is desirable to further adjust the pH during electrolysis in non-diaphragm cells, when using diaphragm cells...adjustment is achieved virtually automatically by the movement of ions through the diaphragm. Low acidity during electrolytic operation requires only an initial primary PH adjustment and only a secondary additional PH adjustment. The... of the effluent can be adjusted by the addition of an alkali, preferably caustic soda, but other alkalis such as soda carbonate or ammonia can also be used, or by adding e.g. sodium acetate to the effluent. It can be used as a pH buffer.

Zinc concentration in viscose effluent is usually 0.1-1.0%
10% compared to zinc sulfate solution for electrolytic sampling.
~100 times thinner. Furthermore, the organic compounds present are of the type that can damage common anode materials (eg, platinum, lead, lead oxide). Therefore, the electrolytic recovery of metallic zinc from viscose rayon factory effluent is as follows: (a)
It is preferred to use an electrolytic cell having an anode corrosion protection diaphragm, (b) a rotating cylindrical electrode to provide an economically acceptable current density.

In preferred embodiments of this invention: (a) zinc electrowinning techniques; (b) organic electrochemical techniques for diaphragms; (c) rotating cylindrical electrode techniques; and (d) pH adjustment of the viscose effluent. , combine.

Aluminum is the preferred cathode material, although any electrode material commonly used in electrowinning can be used for the electrolysis of effluent from viscose plants.

This process is all about the separation of zinc from the catholyte and the formation of sulfuric acid in the anolyte, in the electrolysis of the effluent from a viscose rayon plant using an anion exchange membrane.

That is, both zinc and sulfuric acid are recovered by this electrolysis. This is one of the advantages.

Another advantage is that the recovered zinc is dissolved together in the recovered sulfuric acid to produce a strongly acidic solution of zinc sulfate (eg 4%), which can be used in the rayon manufacturing process. The present invention will be explained by way of examples with reference to the accompanying drawings. 1 and 2, a rotating cylindrical or rotating drum cathode 10 is separated from a generally concentric anode 11 by a membrane or diaphragm 12 defining an anode and cathode chamber.

The membrane may be a cation exchange membrane, e.g. NafiOn, where the metal being recovered is copper, or an anion exchange membrane, e.g. NafiOn, where the metal recovered is copper.
Onac) MA3472, in which case the metal recovered is zinc. The anolyte is introduced into the electrolytic cell through the hole 13 and discharged through the hole 14. The catholyte (electrolyte) is introduced into the cell through an inlet 15 at the bottom of the cell and an outlet 19 at the top of the cell.
is discharged from. Alternatively, hole 1 in the tank casing
A tube 16 leading to the cathode chamber via 7 may also be used. In this way, catholyte may be introduced into the bath through one of the tubes 16 and discharged through the other tube. If desired, the inlet and outlet may be at both ends of each tube. The drum 10 has a scraper 1.8 provided for removing metal adhering to the cathode as the cathode rotates. As shown, the scraper 1 extends the entire length of the cathode, but alternatively the scraper 1 may be provided reciprocating over a fraction of the length of the cathode. In FIG. 3, the motor 30 has a bearing 33 (without a tightening ring) and a
4 (with a tightening ring) is connected to a shaft 32 rotatably provided by a belt drive 31.

This shaft is connected to a slip ring assembly 35 for supplying current to a rotatable drum cathode 36 mounted on the shaft within electrolytic cell 37. A water-cooled housing 38 is provided over the tank, through which the shaft passes with seals 39,40. The tank anode 41 is concentric with the drum cathode and has a fixed anode electrical terminal 42.
provided by. The vessel has an inlet 43 and an outlet 44 for the catholyte, and an inlet 45 and an outlet 46 for the anolyte. In FIG. 4, a rotatable cylindrical cathode 60 is mounted on a rotatable shaft in a support frame 62 with bearings 61 and is driven by a motor 63 connected to the shaft by a belt drive 64.

The frame is equipped with a scraper 65 for the cathode.
An anode 66 concentric with the cathode is located in an anolyte chamber 67 with a cooling coil 68, and the cathode and anolyte chamber are housed within a polypropylene drum 69. A portion of the wall of the anolyte chamber between the anode and cathode is formed by an ion exchange membrane 70. Electrical contacts 71 and 72 are provided at the anode and cathode, respectively, and the drum 69 is provided with a heater 73 and a thermometer 74. In FIGS. 5 and 6, the main shaft 105 is rotatably mounted on a bearing 106.

The main shaft rotates by transmitting power from a variable speed motor 107 to its upper end via a drive belt 108. The lower end of the main shaft extends into the electrolytic cell 110 through the seal 109 . A liquid inlet 111, a liquid outlet 112, and a drain valve 113 are attached to the electrolytic cell 110. A cylindrical electrode 114 is attached to the lower end of the main shaft 105 so that it can rotate together with the main shaft. A counter electrode 115 is mounted inside the electrolytic cell and surrounds the rotating electrode 114 to uniformly expose its electrode surface to the rotating electrode. Since the height of the liquid level in the electrolytic cell is determined by the position of the electrolyte outlet 112, the electrodes can be reliably immersed in the electrolyte. The current is passed through a slip ring assembly 116 mounted on the main shaft 105 to the rotating electrode 114 (
In FIG. 7, a diaphragm 117 separates a counter electrode 115 and a rotating electrode 114 so that an anode compartment and a cathode compartment are formed. The reservoir has a diaphragm forming isolated anode and cathode compartments, for which reason the anolyte (eyelight) is circulated in a separate circulation system and returned to the reservoir. The electrolyte (containing metal powder and hydrogen gas generated by electrolysis) from the cathode compartment is sent to a gas separator,
Here, hydrogen is separated from the electrolyte and metal particles.
In a wet cyclone separator (a device well known in the art), a wet cyclone separates metal powder from most electrolytes. The needle is a conical needle, in which the slurry metal powder with the residual electrolyte sent from the separator is concentrated and can be automatically discharged from the bottom of the cone; This produces a very thick slurry that can be further processed if necessary. The electrolyte separated in the cyclone separator is returned to the wet cyclone separator. The bulk of the electrolyte from the separator is sent to a reservoir, from where it is circulated to the cathode compartment of the rotating electrolyzer. Circulation of the anolyte and electrolyte is carried out by a pump P. In FIG. 9, a rotating cylindrical cathode 130 is mounted on the main shaft.

This main shaft can rotate inside the bearing 131, and
It is driven by the force of a motor 132 which is connected to the main shaft by a drive belt 133. The electrolytic cell is the main shaft Shinil 1
It is sealed at both ends by 34. At one end of the spindle is a slip ring and brush block assembly 135.
There is. FIG. 10 is an elevational view of only the electrolytic cell shown in cross section. This consists of an electrolytic cell main frame 136 partitioned into 10 sections by wall plates 137. The cathode compartment within which the cylindrical electrode 130 rotates is connected to the lid 14.
4 and a diaphragm 139 (FIG. 11) for sealing on either side. Cell lid 144 is sealed to the main compartment of the cell by a rubber gasket 148. The septum is sealed against a rubber seal 140 and supported by a septum support 142. An electrolyte inlet 145 and an electrolyte outlet 146 are provided in the cathode compartment. The compartment is also provided with a product reservoir 149 and a product outlet 143. There are thus ten closed compartments separated from the anolyte and anode compartments. catholyte (
After being supplied to the inlet 145, the Calilite moves from the first compartment to the second compartment through a gap provided in the board around the main shaft.

In this way, the electrolyte moving through the cell passes from the first compartment to the second compartment, then to the third compartment, and so on, with the electrolyte reaching the last compartment then exiting the outlet 146.
It passes through and exits the electrolytic cell. The interstitial holes in the board are arranged to minimize back-flow mixing. The anolyte compartment is between the septum 139 and the anolyte compartment sidewall.

These anolyte compartment side walls are in close contact with the electrolytic cell main frame 136 by rubber gaskets 147. Two anodes 141 are provided within the anode compartment. Electrical connections are made between the anode 141 and the slip ring and brush assembly 135. The invention is further illustrated in the following examples.

The current efficiency in each embodiment is defined by Farade's law, which is well known to those skilled in the art. The term "yield" refers to the effect of the entire process, including, for example, mechanical loss within the system, and is different from the above-mentioned current efficiency in this respect. In Examples 1 to 21, each symbol is used with the following meaning.

10: Current (ampere) actually used to generate metal powder in the electrolytic cell.

That is, the total current multiplied by the current efficiency for metal deposition. C: Concentration of precipitated metal ions in the liquid (Pp
m). : Peripheral velocity of rotating cylindrical electrode (Cm/Sec). Example 1 Using the electrolytic cells shown in FIGS. 1 and 2 and the electrolytic cell device shown in FIG. 3, a cylindrical electrode with an area of 1687 cI11 was provided.

The cylindrical body was heated at 810r. p. m. Rotate with and set the peripheral speed to 1000? /Sec. A sulfuric acid solution containing copper sulfate was pumped into the electrolytic cell at a temperature of 60° C. and a speed of 11/sec. The copper concentration at the inlet was 350 ppm, but because it was diluted to 200 ppm in the electrolytic cell, the concentration at the outlet was 200 ppm. A current of 700 Amps was passed for 4 hours, during which the current efficiency for copper deposition was 72%, and 6009 copper powders were obtained per hour at a current density of 300 mA/d.

The process of this example is IO=4.38×10-3CV0・
92 allows you to express yourself. Example 2 The electrolytic cell described in Example 1 was used, with the flow rate and temperature unchanged.

The cylindrical body was heated at 320 rpm. p. m. Rotate at 393C and set the peripheral speed to 393C! ! It was set as L/Sec. The copper concentration at the entrance is 9
However, since it was diluted to 680 ppm in the electrolytic bath, the concentration at the outlet was 680 ppm. 700
A current of Amps was applied for 2 hours.

The current efficiency for copper deposition during that period was 93%, and 3
86n! 7709 copper powder was obtained per hour at a current density of 7709. The process of this example is IO=3.93×10-3C
By 0.92, you can express yourself. Example 3 Using the electrolytic cell described in Example 1, a cylindrical body was heated at 440 rpm without changing the flow rate or temperature. p. m. Rotate it with
The peripheral speed was 541 cm/Sec.

The copper concentration at the inlet was 571 ppm, but because it was diluted to 385 ppm in the electrolytic cell, the concentration at the outlet was 385 ppm. 700Amps current 4.2
It was flushed for 5 hours.

The current efficiency for copper deposition during that time is 80%, 33
664 g of copper powder was obtained per hour at a current density of 2 mAΔd. The process in this example is IO=4.45X10-3C
It can be described by 0-92. Example 4 The electrolytic cell described in Example 1 was used without changing the flow rate or temperature.

The cylindrical body was heated to 1380r. p. m, and the peripheral speed is 1
698 儂/Sec. Copper concentration at the inlet is 200pp
However, since it was diluted to 98 ppm in the electrolytic cell, the concentration at the outlet was 98 ppm. 550A
A current of mps was applied for 4 hours.

The current efficiency for copper deposition during that time is 70% and 22
4569 copper powders were obtained per hour at a current density of 8 mA×d. The process of this example is IO=4.2X10-3CV
It can be described by 0'92. Example 5 The electrolytic cell described in Example 1 was used without changing the flow rate or temperature.

The cylinder was heated to 810r. p. m, and the peripheral speed is 10
00 (7rL/Sec.The copper concentration at the inlet was 81p.
pm, but since it was diluted to 50 ppm in the electrolytic cell, the concentration at the outlet was 50 ppm. 285 Am
A current of ps was applied for 3 hours.

The current efficiency for copper deposition during that period was 37% and 6
1259 copper powders were obtained per hour at a current density of 2.5 mA/d. The process in this example is IO−3.67×10−
It can be described by 3CV0.92. Example 6 The electrolytic cell described in Example 1 was used without changing the flow rate or temperature.

The cylinder was heated to 810r. p. m. , and set the peripheral speed to 1.
000CTL/Sec. The copper concentration at the entrance is 330
ppm, but since it was diluted to 190 ppm in the electrolytic cell, the concentration at the outlet was 190 ppm.
A current of 600 Amps was applied for 2.5 hours.

The current efficiency for copper deposition during that period was 86%, and 3
6129 copper powders were obtained per hour at a current density of 0.08 mA/i. The process in this example is IO=4.72×10−3
It can be described by CV0.92. Example 7 Example 1
The electrolytic cell described in 1 was used, and the flow rate and temperature were not changed.

The cylinder was heated to 810r. p. m. , and set the peripheral speed to 1.
00 (1-J mo V1/Sec.The concentration of copper at the inlet was 368 ppm, but since it was diluted to 193 ppm in the electrolytic cell, the concentration at the outlet was 193 ppm.A current of 1000 Amps 1.

It was flushed for 5 hours.

The current efficiency for copper deposition during that time is 50%, and 2
5939 copper powders were obtained per hour at a current density of 96 mA/Crl. The process in this example is IO=4.17×10
-3CV0-93. Example 8 An electrolytic cell (shown in FIG. 4) equipped with cylindrical electrodes having an area of 200 (1771) was used.

The electrolyte was sodium sulfate (solution 46) with pH 4 at 60°C.
1 contains 10 kg of anhydride). 1 cylinder
800r. p. m. Rotate at a peripheral speed of 719cm/
Sec. A zinc sulfate solution was continuously added to this electrolyte to maintain the zinc concentration at 400 ppm. Add sulfuric acid and P
H was maintained at 4. 50AnT)s current for 1 hour 10
I let it flow for several minutes.

The current efficiency for zinc powder deposition during that period was 46%, 115 mA/Cw! 28 g of zinc powder was obtained per hour at a current density of . Example 9 The vessel described in Example 8 was used.

The electrolyte and temperature were also the same. The cylinder was rotated at 1800 rpm to give a peripheral speed of 719C771/sec, and zinc sulfate solution was continuously added to the electrolyte to maintain a zinc concentration of 431 ppm. The pH was maintained at 4 by adding sulfuric acid. A current of 50 A was applied for 45 minutes.

During this period, the zinc powder electrodeposition current efficiency was 37.4%,
Zinc powder was produced in the bath at a current density of 93.5 mA/~22.89/hr. This method is based on IO-2.2.104
It can be expressed by C0.806. Example 10 The vessel described in Example 8 was used.

The electrolyte and tank were also the same. The cylinder was rotated at 1800 rpm to give a peripheral speed of 719 cm/sec, and zinc sulfate solution was continuously added to the electrolyte to maintain a zinc concentration of 458 ppm. The pH was maintained at 4 by adding sulfuric acid. A current of 50 A was applied for 2 hours.

During this period, the zinc powder electrodeposition current efficiency was 58%, and 359/hr of zinc powder was produced in the bath at a current density of 144 mA/d. This method is IO-2.7.10'4CV0.8
It can be expressed by 32. Example 11 The vessel described in Example 8 was used.

The electrolyte was waste liquid from a viscose rayon factory with a pH of 4 and a temperature of 60°C. Rotate the cylinder at 1800 rpm to make 719 (
1-JMoV! The zinc sulfate solution was continuously added to the electrolyte to maintain a zinc concentration of 418 ppm.
The pH was maintained at 4 by adding sulfuric acid. A current of 50 A was applied for 1 hour.

During this period, the zinc powder electrodeposition current efficiency was 40.5%, and the bath was 101 mA/c! Zinc powder was produced at a current density of 24.79/h. This method is 10-2.3.104
It can be expressed by CV0J313. Example 12 Smaller than the tank described in Example 1, but otherwise similar;
A tank with a cylindrical electrode having an area of 200 cTi1 was used.

The electrodes were made of galvanized stainless steel. The electrolytic solution was a 1 molar sodium sulfate solution with a pH of 4 and a temperature of 60°C. Rotate the cylinder at 800 rpm and set the peripheral speed to 319
cm/sec, and the zinc concentration of the new electrolytic solution was maintained at 450 ppm by adding a zinc sulfate solution. The electrolyte was pumped into the cell at a rate of 41/min, the inlet concentration was 450 ppm zinc, which was diluted in the cell to 350 ppm zinc, and the outlet concentration was 350 ppm zinc. A potential difference of 1.86 V was maintained between the rotating cylindrical electrode and a nearby mercurous monosulfate reference electrode, thereby making the rotating cylindrical electrode a cathode with respect to the reference electrode. This caused a current of 28 A to flow, and this was maintained for 4 hours. During this period, the zinc powder electrodeposition current efficiency was 71%, and 24.49/hr zinc powder was produced at a current density of 100 mA/(711) in the bath.
It can be expressed as O=3.58.10'4CV0'88. Example 13 The vessel described in Example 12 was used.

The electrolyte and temperature were also the same.

The cylinder is rotated at 1200 rpm and the peripheral speed is 479c.
m/sec, and a zinc sulfate solution was added to maintain the zinc concentration of the new electrolytic solution at 430 ppm. The electrolyte was pumped at a rate of 42/min. The inlet concentration is 430 ppm zinc;
This was diluted to 350 ppm zinc in the tank and the outlet concentration was 350 ppm zinc. A potential difference of 17 V between the rotating cylindrical electrode and a nearby mercury monosulfate reference electrode was maintained to make the rotating cylindrical electrode negative with respect to the reference electrode. This caused a current of 16 A to flow, and this was maintained for 3 hours. During this period, the zinc powder electrodeposition current efficiency was 100%, and the bath had 8
19.59/hr of zinc powder was produced at a current density of 0 mA/Cd. This method is IO=2.67.104CV0・
833. Example 14 A tank similar to that described in Example 8 was used.

The electrolyte was copper phthalocyanine manufacturing waste and contained sulfuric acid, sodium chloride, urea and other organic chemicals. The temperature was '60°C. The cylindrical electrode was made from titanium that had been roughened beforehand by etching in concentrated hydrochloric acid, and the surface area of the cylindrical electrode was 200 d. Rotate the cylinder at 645 r and increase the peripheral speed to 257 (1-J mo V!
/second. A potential difference of 0.4 between the rotating cylindrical electrode and the nearby saturated Kanaga reference electrode was maintained, with the rotating cylindrical electrode serving as a cathode with respect to the reference electrode. The starting concentration of copper in the electrolyte is 95p
pm, resulting in an initial current of 9.25A. Copper concentration and sliding current are 2.5 ppm and 10.2 A after 90 minutes, respectively.
decayed exponentially. This method is IO=5.59.10′
It can be expressed by 4CVq93. Example 15 The vessel described in Example 14 was used.

The electrolyte, electrodes, temperature, and rotation speed were also the same. The potential of the rotating cylindrical cathode is set to −0 with respect to the nearby saturated Kanaga electrode.
．． It was held at 5V. The starting concentration of copper was 15 ppm and the initial current was 2.8 A. The copper concentration and sliding current decayed exponentially to 1 ppm and 10.9 A, respectively, after 50 minutes. This method can be expressed as IO=9.3.10-chiCO.955. Example 16 The vessel described in Example 14 was used.

The electrodes were also the same. The electrolyte contains 3,500 ppm of sodium chloride, ammonium chloride, and zinc, and 250 ppm of arsenic.
pm, platinum at 20 ppm, palladium at 120 ppm
[n, rhodium at 120 ppm, ruthenium at 45
ppm, iridium at 25 ppm, and some silver and gold in a 0.5N hydrochloric acid solution. The temperature was 60°C. The potential of the rotating cylindrical cathode was held at −0.2 with respect to the saturated Kanaga electrode nearby, and the cylindrical electrode was rotated at 40 rpm to give a circumferential speed of 160 cm/sec. The initial current was 16A, which decayed to 2A after 200 minutes. Powder metal products included zinc, arsenic, platinum, palladium, rhodium, ruthenium, iridium, silver and gold.
This method can be expressed by IO=2.46.104C0.93. Example 17 The vessel described in Example 8 was used.

The electrodes are made of smooth stainless steel and are rated at 125
Rotate at 0 rpm and achieve a peripheral speed of 500 CT! It was set as L/second. Electrolyte is 500ppm nickel and 500ppm
ammonium sulfate solution (4611
1 kg). The temperature was 35°C. The potential of the rotating cylindrical electrode is -1.5 with respect to the nearby saturated Kanaga reference electrode.
was held at This caused a current of 30 A to flow, and a strong solution of nickel (115 g/l) and iron (509/l) was added for 3 hours to maintain the nickel concentration. Nickel powder was produced with a current efficiency of 28%. This nickel powder is 9
It was analyzed to be 9.1% nickel and 0.25% iron. The cylindrical electrode was electrodeposited with very fine nickel powder and was substantially smooth. This method uses IO=1. ．．
It can be expressed as 3.10′4C0・79. Example 1
8 The electrolytic cell described in Example 8 was used.

The cylinder was rotated at 1250 rpm, giving a surface velocity of 500 ml sec.

The electrolyte was a strong sulfuric acid solution (150 g/l) containing nickel (8 y/l), arsenic (29/l) and copper (230 ppm).
). Sulfuric acid (1509/l), Nickel (399/l)
A replenishing electrolyte containing arsenic (5 g/l), arsenic (5 g/l) and copper (36 fl/l) was added to maintain the copper concentration. 50A
A current of 8 hours was passed, and the efficiency for copper powder precipitation during this period was 78%, and this cell produced a current of 196 mA/CTil.
46 f1 of copper powder was produced per hour at a current density of .

The recovered copper powder was analyzed to be 95% copper, 0.2% nickel and 3% arsenic. The cylinder was substantially rough with extremely coarse copper powder deposits on its surface. This method is o
-4. ．． 5.10″4C0·953.Example 19 A small electrolytic cell otherwise identical to that described in Example 1 was used.

This cylindrical electrode had a surface area of 500 d. The electrodes were galvanized aluminum. The electrolyte was a discharge solution in viscose rayon manufacture and contained a high concentration of sodium sulfate and 62 ppm iron. The electrolytic solution was maintained at 60° C. and pH 4.5. Cylinder is 800 rpm
Rotate with surface speed 372? /second was given. Viscose rayon effluent (2,500 ppm zinc concentration) was added to maintain a 420 ppm zinc concentration in the feed to the cell. The electrolyte was pumped into the cell at a rate of 41/min. The inlet concentration was 420 ppm zinc and this concentration was diluted in the electrolytic cell to 340 ppm so the outlet concentration was 340 ppm zinc. A potential difference of 1.7 between the rotating cylindrical electrode and near the mercury monosulfate reference electrode was maintained such that the rotating cylindrical electrode was positive with respect to the reference electrode. This produced a current of 23A which was maintained for 5.5 hours. The current efficiency for zinc powder precipitation during this period was 66%,
The electrolytic cell produced 18.59 zinc powder per hour at a current density of 31 mA/(1-J moVf). The partially oxidized recovered zinc powder was analyzed to be 55% zinc and 0.6% iron. This method is IO=4.5.104C0・78
It can be explained as follows. Example 20 The same electrolytic cell as in Example 1 was used except that it was larger.

The surface area of the cylindrical electrode was 5,900 (-d). The electrode was smooth titanium. The cylinder was rotated at 460 rpm giving a surface velocity of 1,112 cm/sec. The copper concentration in the inlet was 362 ppm, diluted to 234 ppm in the electrolyzer and the outlet concentration was 234 ppm.
It was m. A current of 1,000 ppm was applied for 14 hours.

During this period, the current efficiency for copper deposition was 78%, and 9259 copper powders were produced per hour at a current density of 170 mA/C7l using the electrolytic cell. At the end of implementation,
The titanium cylinder had virtually no copper remaining on its surface and was substantially smooth. This method is 10=7.2.10-3C
It can be explained as 0.875. Example 21 The electrolytic cell of Example 20 was used.

The rotating cylindrical electrode is hard-plated copper on titanium (0.47!
LTIL thickness). The cylinder was rotated at 460 rpm, giving a surface velocity of 1,112 CTrL/s, PH
Copper sulfate-containing sodium sulfate solution of 2.
It was pumped into the electrolytic cell at a rate of 1/sec. The inlet concentration was 350 ppm copper, diluted to 150 ppm in the electrolytic cell, thereby giving an effluent concentration of 150 ppm. A current of 2,000 A was applied for 36 hours, and the current efficiency for copper deposition during that time was 62%, and the current efficiency was 210 mA/
1,4 per hour by the electrolytic cell at a current density of Cd
709 copper powders were produced.

At the end of the run, the copper cylinder had a copper powder coating on its surface and the surface was rough. This method uses IOl3.
It can be expressed as 1O-3CV0.92. Example
22 The electrolytic cells shown in Figures 9, 10 and 11 were used.

The total cylinder length was 1000m, and the effective length of each part of the rotating cylinder in each room was 9cr1L. The cylinder diameter is 7. ．． 62CTfL, and the cylinder was rotated at 2,000 rpm to give a surface velocity of 800Cr1L/sec. The electrolyte, which is an effluent from copper phthalocyanine production and contains sulfuric acid, sodium chloride, urea and other organic chemicals, was pumped into the electrolytic cell at a temperature of 60° C. and a flow rate of 61/min. The electrolyte in the anode chamber was 1N caustic soda, and the anode was made by Nitsukel. 40 in 4
A current was applied to the electrolytic cell and continued for 4 hours.

During this time, the copper concentration in the inlet and each chamber was analyzed as follows. The copper powder produced during this electrolysis remained in each chamber, either on the cylinder or in some part of the chamber. This method is expressed as follows: (8) where 10 is the current (4) in each chamber producing the powder precipitate.
C is the copper concentration (Ppm) in the chamber of the electrolytic cell, and V is the surface velocity of the rotating cylinder (C!!L/sec).

After this electrolysis period, empty the electrolytic cell and add 201 of water and 5
A solution consisting of 70% nitric acid of 2,000 ml of cylindrical electrode
It was slowly pumped into the electrolytic cell while rotating at rpm. The copper powder on the cylindrical electrode and the copper powder in the electrolytic bath were
Complete dissolution over 0-60 minutes yielded a solution containing 19.59/l copper. Two electrolytic cells, number 9 and 11, can be used to facilitate continuous extraction of copper and other metals. One electrolytic cell is used for electrolysis, while the metal is melted in the other electrolytic cell.

These two electrolytic cells can be placed in front of the electrolytic cells according to FIGS. 1 and 2, so that the metal solution can be recirculated. The elution method described in Example 22 may be performed depending on the metal to be dissolved, e.g.
HCI, NaOH, NH4OH or NaCN-NaO
H can be used as a chemical solvent. Alternatively, or in addition, the rotating cathode electrode can be a cathode, thereby causing dissolution of the metal at the anode electrode. Generally, the advantages of the present invention are summarized as follows.

Metals can be continuously and effectively extracted from industrial effluents and other dilute liquids by the method of the present invention.

The amount of metal transfer in the rotating cylindrical cathode cell of the present invention is up to 1000 times greater than in a conventional flat tank cell. Production of the metal as a powder facilitates recovery of the metal from the electrolytic cell.

The use of a diaphragm electrolyzer avoids and reduces anode corrosion due to impurities so that dirty effluent can be treated.

Apart from its use in metal manufacturing, the invention has use in pollution prevention.

Effluents from which metals can be removed according to the invention can be treated by biological means to remove organic impurities before release.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a rotating cylindrical electrode diaphragm tank. FIG. 1 is a cross-section taken along the line BB in FIG. 2, and FIG. 2 is a cross-section taken along the line AA in FIG. 1. FIG. 3 shows the general arrangement of the vessels shown in FIGS. 1 and 2. FIG. Figure 4 shows the test tank. FIG. 5 is a longitudinal sectional view of a large rotating electrode tank without a diaphragm. FIG. 6 is a horizontal sectional view taken along the cutting line shown in FIG. 5. FIG. 7 is a horizontal sectional view corresponding to FIG. 2 of the diaphragm tank. 8th
The figure is a flow diagram illustrating the metal recovery process. FIG. 9 is a plan view of a complete horizontal operating tank with shaft and drive motor. FIG. 10 is a sectional front view of only the tank. FIG. 11 is a front view of the end section of the tank only. Drawing abbreviation, 10...Rotating cathode, 11
... Anode, 12 ... Diaphragm, 13.
...hole, 14...hole, 15...
Liquid inlet, 16...tube, 17...hole, 1
8...Scraper 1, 19...Liquid outlet, 30...Motor, 31...Belt drive, 32...Shaft, 33...・・・・・・
・Bearing, 34...Bearing, 35...Slip ring assembly, 36...Drum cathode,
37... Electrolytic cell, 38... Water cooling housing, 39... Seal, 40... Seal, 41... Anode, 42... ...Electrical terminal, 43...Liquid inlet, 44...Liquid outlet, 45...Liquid inlet, 46...Inlet/outlet, 60... ... Cylindrical cathode, 61 ... Bearing, 62 ... Support frame, 63 ...
Motor, 64...Belt drive, 65...
... Scraper 1, 66 ... Anode, 6
7...Anolyte chamber, 68...Cooling coil, 69...Drum, 70...Ion exchange membrane, 71...Electrical contact , 72... Electric contact, 73... Heater, 74... Thermometer, 105... Main shaft, 106... Bearing, 107・・・・・・Variable speed motor, 108...
... Drive belt, 109 ... Seal, 110
..... Electrolytic cell, 111 ..... Liquid inlet, 11
2...Liquid outlet, 113...Drain valve, 114...Rotating electrode, 115...
Counter electrode, 116...slip ring assembly,
117...Diaphragm, 130...Rotating cylindrical cathode, 131...Bearing, 132...
・Motor 133... Drive belt, 134.
... Main shaft seal, 135 ... Brush block assembly, 136 ... Electrolytic cell main frame, 137.
・・・・・ Diameter board, 139 ・・Diaphragm, 140
...Rubber seal, 141 ... Anode, 142 ... Diaphragm support, 143 ...
・Product outlet, 144... Lid, 145...
・Electrolyte inlet, 146... Electrolyte outlet, 147
...Gasket, 148...Gasket, 149...No product.

Claims (1)

[Claims] 1. It consists of electrolyzing a dilute aqueous solution of a metal in an electrolytic cell having a rotating cylindrical cathode, and the electrolysis is carried out by the following formula: I=KCV^x (where I is the current density) K is a constant substantially determined by the metal being electrolyzed, the temperature and the electrolytic cell; C is the concentration of metal ions in the aqueous solution; V is the circumferential velocity of the rotating cylindrical cathode; and , x is 0.7 to 1.0
It is. ) A method for producing metal powder from a dilute aqueous solution of metal. 2 K is 5
The method according to claim 1, wherein: x10^-^8 to 5x10^-^6. 3 Dilute aqueous solution contains 2 to 10,000 ppm of metal ions
A method according to claim 1 or 2 containing.