RU2471007C1 - Extraction method of metals capable of hydrogen absorption from metals, and plant for its implementation - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: reduction is performed with hydrogen generated in solution; at that, reduction is catalysed with reduced metal itself, which is contained in finely dispersed state. Reduction process is performed in multi-pass reactor at variable pressure that is changed with frequency of 1-5 Hz from maximum to minimum values of 8 kg/cm² to 0.25 kg/cm². Extraction plant of metals capable of hydrogen absorption from solutions includes dosing device, modified displacement pump, electrolyser for hydrogen generation and multi-pass reactor in the form of labyrinth.

EFFECT: simplifying the process and improving the purity of extracted metal.

10 cl, 9 dwg, 8 tbl, 4 ex

Description

The invention relates to a method for the separation of metals capable of absorbing hydrogen from solutions, including a reduction step, and also to a plant for its implementation. This method can be used in the field of waste processing of spent catalysts containing precious or expensive metals, in technological processes of processing precious and non-ferrous metals, namely the processing of scrap metal containing precious metals or in the extraction of non-ferrous and precious metals from industrial solutions, as well as in processing radioactive materials for the separation of metals from nuclear waste, with the goal of reuse or a more compact dry burial.

The most common methods for the industrial separation of metals from solutions can be reduced to two main groups of processes. The first group is the precipitation of metals in the form of insoluble compounds, for example salts, hydroxides and the like. The resulting precipitation is sent to further pure metal recovery operations. The second group is the direct reduction of the target metal in solution by reducing agents. Among the reducing agents described and used are compounds of formic acid, hypophosphite, hydrazine borohydrides and others. A fairly common way to restore one metal to another, more electronegative. This method has a trivial name - cementation.

From Russian patent RU 2085497, a method is known for the separation of palladium from feedstock, including the dissolution of the precipitate and subsequent reduction of palladium, however, this method is strictly limited to the raw materials from which palladium can be isolated, the concentration of nitric acid used, and the hydrogen reduction process is carried out at elevated temperatures (80-90 ° C), which requires increased safety measures.

Also known (copyright certificate SU 1673616) is a method for the separation of nickel from spent solutions of chemical nickel plating, including its reduction from solutions of sodium hypophosphite. According to this method, nickel recovery is carried out in the presence of nickel powder at a pH of 6.5-7.0, 65-70 ° C and a ratio of the content of nickel ions and sodium hypophosphite 1: 5. The disadvantage of this method is the use of a significant excess of reducing agent, leading to contamination of the resulting metal, the use of high temperatures, as well as the need for the recovery process in a strictly limited region of the pH of the solution.

Closest to the proposed technical essence and the achieved result is a method for producing palladium metal from solutions described in Russian patent RU 2154685. According to the technical solution presented in this source, formate ions are introduced into the initial acidic or alkaline solution containing palladium and chlor-ions . Palladium is reduced to metal. In the resulting solution containing palladium powder, a compound containing palladium and chlorine ions and formate ions are again introduced. The process is repeated at least two times. The result is metallic palladium in the form of a powder of a given size with homogeneous particles.

The disadvantages of the prototype method are the need to use for the process of restoring high temperatures (from 55 to 98 ° C), which in the case of aggressive environments requires special precautions when implementing the method, the use of stoichiometric amounts of an organic reducing agent, which undoubtedly leads to a residual content of the reducing agent and reaction products in the resulting metallic palladium, the presence of waste solutions containing organic compounds.

Thus, all known methods of metal separation from its solution, regardless of technical nuances, have one common drawback - they require the addition of certain (additional) foreign substances - precipitants of reducing agents or the like to the metal to be released.

Therefore, the objective of the present invention is to develop a method for the separation of hydrogen-absorbing metals from solutions, eliminating the above-mentioned disadvantages of the aforementioned in the prior art, and also to propose an apparatus by which this method can be implemented.

The problem is solved by the proposed method for the separation of metals capable of absorbing hydrogen from solutions, including a reduction step, the difference of which is that the reduction is carried out with hydrogen generated in the solution, and the reduction is catalyzed by the reduced metal itself in a highly dispersed state, and is carried out in a multi-pass reactor at variable pressure, which varies with a frequency of 1-5 Hz from maximum to minimum values - from 8 kg / cm ² to 0.25 kg / cm ² .

The chemical principles of the process proposed by this method and the developed design of the installation allow achieving high reaction rates. The reduction reaction takes place in seconds in the entire volume of the multi-pass reactor. The process in terms of speed can be characterized as an instantaneous “discharge” of all the deposited metal in the reaction space.

In the proposed method of metal recovery, a high process speed is achieved: a) using the most chemically active forms of the reducing agent and catalyst, b) constructive solutions of the installation, giving the indicators of mass transfer, not achievable by any stirring by the mixers.

These technical solutions made it possible to abandon heating altogether for intensification purposes. The target reaction occurs at room temperature and even lower.

As a result, the opportunity arose not only to save money (on coolants), but also to abandon metal in the manufacture of equipment. All pieces of equipment are made of polymers. The lack of heating and work with hot solutions and steam greatly reduced the release of heat and vapor in the production room, significantly improved the working conditions of personnel and the composition of ventilation emissions into nature.

All known methods of precipitation of metals or their compounds from solution by other substances are carried out with stirring and heating, followed by cooling.

The proposed method and installation for the first time allowed the process of chemical reduction of metal in ionic form, from solution - immediately to a metallic state - in continuous mode.

All known industrial methods for the chemical separation of metals from a solution are periodic, including operations of loading, unloading, settling, filtration, and others.

According to the method claimed in the invention, metals capable of absorbing hydrogen are metals selected from the group consisting of palladium, platinum, nickel, cobalt, ruthenium, rhodium, gold, iron and titanium. Most preferably, such metals are palladium, platinum, nickel and cobalt.

Acid and neutral metal solutions can be used in the method according to the invention. This can be both aqueous solutions of salts of metals released, and metal-containing solutions of mineral acids, preferably hydrochloric and / or nitric acids. As an example, in the latter case, a solution coming from the industrial operation of palladium dissolution from spent alumina catalysts of the APK-2 series can be indicated.

The process of this invention is heterogeneous catalytic. In the reaction, substances participate in it immediately in three states - liquid (metal ion solution), solid (metal catalyst) and gaseous (hydrogen). For such processes, the creation of the highest possible mass transfer is important. Therefore, to implement the method according to the invention, it is necessary to create an alternating hydraulic pressure in a multi-pass reactor. Variable pressure during the recovery process according to the claimed method is provided as a result of the reciprocating movements of the solution created by the modified membrane pump and due to the design of the multi-path reactor.

A multi-path reactor is a system of series-connected loops (Fig. 6a), with each loop consisting of alternating straight sections going to the right and left of the loop junction, and sharp turns. In a particular case, the reactor is a monolithic block of plexiglass, in which a corresponding network of channels has been made (Fig.6b). The length of straight sections can be 30-100 mm in each direction from the center, the diameter of the channels and turns is 12 mm. A total of 60 turns in a multi-path reactor at an angle of 90 ° and 40 straight sections of the “acceleration-braking” reaction mass. In a preferred embodiment, the total length of the channels is 3700 mm, the length of the straight sections is 2800 mm and the turning sections are 900 mm. The volume of fluid in the labyrinth is 0.4 dm ³ .

When the membrane pump is operating, the reaction mass with a working frequency of 1-5 Hz (sec ^-1 ) of the double strokes of the membrane is pumped into the channels and pushed (sucked) from the channels. In the straight sections of the channels under the shock of the membrane pump, an instantaneous acceleration of the solution takes a duration of a millisecond. After which - inhibition of the solution. Due to the high flow rate, high pressures develop.

The formation of high pressure pulses is facilitated by: a high speed of the solution in the channels, high acceleration variables when changing the direction of movement (pumping - suction) and passage of channel turns - of a small (2 × 10 ^-2 m) radius. In this case, forces proportional to the square of the velocity act on the flow: velocity head (Bernoulli), centrifugal force in turns, and medium resistance.

Mathematical calculations of the parameters of the multi-pass reactor were carried out - numerical simulation.

In addition, direct measurements were made of the pressure characteristics in the reactor under the conditions of the proposed process. Actual pressures were measured by a high-frequency sensor, which allows you to see pressure changes in the reactor channel over time intervals of 10 ^-4 sec.

The test results are shown in figures 7-9.

The data of direct pressure measurements in the channel of a multi-path reactor showed that the increase in the amplitude of the direct pressure in the injection phase occurs during 0.2-0.3 ms. In addition to the main pressure pulse, 5-7 additional pulses of smaller amplitude appear in the reactor, and only after this, the pressure drop begins, due to the start of the suction stroke.

That is, the design of the reactor allows you to receive pressure fluctuations with a frequency five to seven times greater than the frequency of the pump.

This property of the reactor (the formation of additional pressure pulses) is due to the multiple reflection of the pressure front in the channels and the presence of pressure fronts in the opposing liquid flows.

The measurements also showed that in the injection phase the pressure rises to 7-8 kg / cm ² , and in the suction phase it decreases to 0.25 kg / cm ² .

All of the above allows you to get the main advantages of this design in a multi-pass reactor:

- the intensification of mixing (mass transfer), which is the most important factor in a heterogeneous (liquid - solid - gaseous) process;

- the impact on the solution of compression-vacuum pulses;

- the effect of centrifugal force arising in turns of small radius during the movement of the solution at high speeds, which presses the solid phase to the channel wall - the effect of centrifugation.

According to the method according to the invention, the reduction is carried out in the presence of hydrogen, which is generated directly in the reaction solution using an electrolytic cell with a separated cathode and anode space.

The resulting hydrogen is absorbed by the finely divided black of the reduced metal. As you know, metals such as nickel and metals of its group, as well as palladium and metals of the platinum group are able to absorb (dissolve) a significant amount of hydrogen. Thus, the reduced form of the metal in solution acts as a catalyst for the reduction process. Therefore, for the initial start of the process, it is required to load directly into the labyrinth a portion of black or finely divided powder of the extracted metal. With further carrying out the process, freshly formed portions of the reduced metal are catalyzed.

The increased solubility of hydrogen in metals is facilitated by the finely dispersed form of the metal — practically a suspension, as well as vigorous mixing of the reaction mass and sharp bursts of variable pressure. Under these conditions, a large amount of solid amorphous transition metal hydrides is formed, that is, compounds of variable composition saturated with hydrogen.

The method according to the invention is carried out at room temperature and does not require additional heating or heat dissipation.

In one embodiment of the invention, the method according to the invention can also be used to isolate a mixture of at least two metals capable of absorbing hydrogen from solutions. Moreover, the metal content in the resulting mixture of reduced metals is controlled by the concentration and feed rate of metal solutions.

Another object of the present invention is an installation for implementing the method of separation capable of absorbing hydrogen metals from solutions, including

- dosing device;

- modified volumetric pump;

- an electrolyzer for generating hydrogen;

- multi-way reactor (labyrinth);

characterized in that it is made with the possibility of creating reciprocating movements of the solution and, as a consequence, variable pressure using a modified diaphragm pump and due to the design of a multi-path reactor.

The installation is configured to change the pressure with a frequency of 1-5 Hz from maximum to minimum values from 8 kg / cm ² to 0.25 kg / cm ² .

For the proposed process, at any time during the steady-state regular operation of the installation, the technological characteristic of any point in the process is a constant. Such an organization of technological processes with stationary flow conditions is most optimal for the purposes and mechanisms of control and automation of processes.

In the well-known extraction technologies, the entire technological cycle is characterized by a constant change in the characteristics of the medium. In these technologies there are non-stationary processes: pumping or unloading of reactors, heating - cooling of reaction volumes, gradual or intermittent dosing of reagents, vigorous stirring with mixers - slow sedimentation of sediments.

The installation diagram is illustrated in the following figures.

Figure 1 - technological scheme of the installation according to the invention.

Figure 2 is a process diagram of a plant according to the invention with a device that determines the residual content of the recoverable metal in solution.

Figure 3 - industrial diaphragm pump.

Figure 4 is a modified diaphragm pump.

Figa - electrolyzer for generating hydrogen.

Fig.5b is a diagram of an electrolytic cell with a separated cathode and anode space.

Figa - diagram of a multi-way reactor with process streams.

Fig.6b - multi-path reactor or labyrinth.

7 is a diagram of pressure changes in the channels of a multi-path reactor during operation of the diaphragm pump.

Fig. 8 is a diagram of pressure changes in the channels of a multi-path reactor during operation of the diaphragm pump in a time range of 0.4 sec.

Fig.9 is a single pressure pulse in the discharge phase.

According to the technological scheme of the device according to the invention (Fig. 1), a fresh solution of the released metal is fed into the reaction space by any metering device, for example, a peristaltic pump 1. By means of a metering device, a fresh solution is fed into the technological path 5 (pipeline) between the membrane pump 2 and the electrolyzer 3.

The feed rate of the fresh solution is controlled by the final metal content at point 6. In one of the preferred embodiments of the installation (Fig. 2), device 6A is installed at point 6, which determines the residual content of the metal to be recovered in the solution, based on the optical sensor, and regulating on the basis of this dispensing solution metering device 1.

In another preferred embodiment, the feed is controlled manually, “until the disappearance” of the light straw color at point 6. For example, palladium solutions are tinted from light brown to light yellow. Visible to the naked eye, a light straw color appears in the solution even with a palladium content of 0.01-0.02% wt. The solution after palladium recovery is colorless and transparent.

The concentration of metal at the outlet of the installation (completeness of extraction) is not critical, since this solution is sent to prepare a fresh solution of the metal salt, that is, “to the head” of the process.

Normal (ordinary) working metal concentrations suitable for extraction in this installation are 1-100 g / l, calculated on the target metal.

A pulsating cycle of a volume pump with a pumping and suction frequency of 60-300 times per minute 1-5 Hz creates a vigorous reciprocating flow in the device.

Rapid acceleration (positive acceleration) and braking (negative acceleration) to a complete stop create alternating forces acting on the solution, therefore, on each of its particles, including microparticles.

High, and more importantly, rapidly changing flow rates in the device create sharp pressure drops from excess to rarefaction.

According to the invention, in the proposed installation, as a modified volumetric pump, it is possible to use any volumetric pump - piston, plunger or otherwise. Preferably, a modified diaphragm pump 2 is used with pneumatic drive from a compressed air network or a stand-alone compressor. Modifications were made to the industrial diaphragm pump, FIG. 3, which had a valve system that sucked in fluid when the membrane moved to the left and injected fluid into the tract when the membrane moved to the right. During the modification, the valve system was removed and drowned. A hole of the required diameter is made in the pump casing. After that, the pump lost the ability to pump liquid, and began to work in the suction mode - injection of the same portion of the solution (figure 4).

In one direct stroke (injection), the pump delivers 0.35-0.5 dm ^{3 of the} reaction solution or 0.8-1.3 volumes of the multi-pass reactor into the installation. The same amount is absorbed by the pump during the return stroke - suction stroke.

The frequency of the pump is controlled by compressed air pressure (pump drive) from the mains or from the compressor.

In one embodiment of the installation, the installation can operate without a pump at all. The pulsation of the liquid with the required speed and volume is provided only by the supply of pulses of compressed air and pressure relief through an electronically controlled valve system. This option makes sense only when working with especially hazardous solutions, for example, in the processing of radioactive solutions.

The diaphragm pump 2, creating pulsating movements, directs the reaction stream through the electrolyzer 3 to the multi-pass reactor 4.

Hydrogen involved in this process has maximum activity if it is obtained directly during the process. The best results are shown by hydrogen if it is formed directly inside the process at the cathode of the electrolyzer and is constantly in contact with the reaction mass: a metal solution, a freshly reduced metal and the solution itself.

To generate hydrogen directly in solution in the device according to the invention, an electrolyzer 3 with a separated cathode and anode space is used (Figs. 5a and 5b).

As a result of electrolysis of the reaction solution, hydrogen is released at the cathode. Anode reactions for carrying out the claimed process do not play a role. However, when working with acidic solutions, products that may be toxic are released on the anode - for example, chlorine gas from hydrochloric acid or related solutions. For this reason, the anode process was removed from the working area and isolated in a separate compartment. A special design of a two-chamber electrolyzer was developed, in which the cathode space is separated from the anode by an ion-exchange membrane.

An independent reaction occurs in the anode compartment, in which there is no environmental pollution. For this, the reaction of electrolysis of dilute alkaline solutions was chosen, in which pure gaseous oxygen was released. Anolyte solution, after repeated prolonged use, is sent to neutralize the acidic solutions of production.

A side reaction at the cathode is the direct electrochemical reduction of a positive metal ion from a solution in the form of compact crystalline precipitates. However, the proportion of this reaction is not large 5-10% of the calculated output "by the passed electric current". The galvanically formed metal is also the target product for this installation. The main reaction at the cathode under these conditions remains the formation of hydrogen.

The basis of the installation according to the invention is a multi-way reactor 4 or a labyrinth (figa), in which in the small volumes of the solution (several hundred milliliters) distributed along the channels of the reactor, extreme speeds and pressures of the solution are created, while changing several hundred times per minute.

High and low pressures in the device were able to constructively be localized in small volumes that do not require the use of apparatuses and a circuit operating under pressure or vacuum.

At the same time, the created device does not transfer potentially explosive (due to the presence of hydrogen in the process) installation to the field of use of expensive equipment designed for high pressures and falling under the special requirements of the Technical Supervision.

All equipment is made of polymer materials, the replacement of which in the usual scheme of working with highly corrosive solutions is only expensive titanium.

A suspension containing a solution of the metal to be recovered and the solid phase of the reduced metal saturated with hydrogen in electrolysis cell 3 is injected with high frequency and returns “to the labyrinth - from the labyrinth”.

In a multi-pass reactor 4, the reaction mass at high speeds reciprocates along straight sections of the labyrinth and in sharp turns.

The reduced metal, saturated with hydrogen, is the strongest reducing agent for an ion of the same metal in dissolved form.

In addition, the reaction mass contains hydrogen in free form, which is released at the cathode. This hydrogen is sorbed or even completely dissolved in the freshly formed black of the target (recoverable) metal, enhancing the reducing properties of the reaction mass. A recovery reaction occurs. The lower circuits of the multi-pass reactor contain the bulk of the recovered black. The main reaction takes place in them - in the actual mode of instant discharge of the entire ionic (dissolved) metal in the formed portions, the fresh reduction of the metal. The process takes 0.5-1 seconds.

From circuit to circuit, as a result of the reduction reaction, the content of the metal ion in the solution decreases. In addition, the solution is freed from the solid phase, which is separated in the lower sections.

During normal operation of a multi-pass reactor, the last 2–3 circuits no longer contain reduced metal — black or powder. Moreover, they do not contain metal in solution. Since the solution, in particular palladium, is painted in a light straw color, already visible to the eye with a content of 0.01-0.02%, visually - by the absence of color it is possible to judge the completeness of the reaction. The solution is removed from the damping tank 9, connected to the atmosphere. The filled volume of the damping tank is at least three times the injection volume of the diaphragm pump. The solution collected from the damping container should be transparent and colorless. With a residual color of the solution (incomplete discharge of the ion), it is sufficient to control the feed rate of the fresh solution by turns of the metering device 1.

The spent solution, from which all the target metal has been planted, goes to the head of the process to prepare new portions. Due to this, the content of residual metal in the solution is not critical.

The finished product — the target metal — is recovered as a highly compacted precipitate from the bottom of the labyrinth. The device for the selection of metal is a valve of the hose type 8. Through the hose valve it is easy to adjust the amount of metal taken. The installation does not stop at this time.

The precipitate does not require filtration, as it is already well sealed, and with the actual residual moisture it enters the drying operation. If the precipitate of the extracted metal is intended for the preparation of technological salts of production, then it is not even dried, but only analyzed for the content of the basic substance.

The purity of the resulting metal from hydrochloric acid solutions is usually 94-96% wt. However, the main impurities are dissolved (and sorbed) gases.

The proposed method and installation have the following advantages.

The metal obtained by the method according to the invention is compact, well squeezed from solution with black. In this form, the metal has the maximum possible specific surface and the oxidized form is practically absent. Such metals are most chemically active, in particular, are able to dissolve, even in non-concentrated acids.

This is a very significant advantage for industries where metal is further used in the technology for producing chemical products. For example: catalysts, salts, technological solutions and others.

The proposed method makes it possible to exclude from the process several costly (metal loss) operations.

Stages such as: precipitation of finely dispersed products in reactors, unloading onto filters and filtration, thorough rinsing from introduced substances - pollutants, unloading of filters become unnecessary.

The exclusion of the above operations from the process gives an exception to the material balance and technological losses that existed on them. When working with non-ferrous, and even more so with precious metals, the maximum degree of their extraction from solutions is the most important requirement for the technological process. In all known processes, incomplete precipitation of a metal from a solution means its actual loss, since contaminated solutions are sent for discharge. Because of this stage, the precipitation of fine products is carried out for hours, and then the precipitates are filtered on micron filters.

In the proposed method, the degree of extraction is generally not critical. Since the technological solution is not contaminated with any additional substances, and after extraction of the target metal from it, it is “wrapped” in the previous operations, it may contain a higher metal content than with the known methods.

For example, if by known technologies in the solution it is required to achieve a residual precious metal content of 10 ^-3 -10 ^-4 %, then in the proposed method it is sufficient to maintain a final concentration of about 10 ^-2 %, that is, the difference is orders of magnitude - hundredths rather than thousandths .

This, in addition to a significant advantage in profitability, makes it possible to work at the highest achievable process speeds, neglecting the indicator - "degree of extraction".

The invention is further explained in more detail in the examples of execution, which however do not impose restrictions on the claimed limits of the invention.

Examples

General methodology:

Before starting work, 100-200 g of recoverable metal in reduced form in the form of the corresponding black is placed in the installation through the loading hole 7. After loading, the installation is filled with the reaction solution using a peristaltic pump 1. After the entire installation is completely filled and air is removed from the stagnant zones, pump 1 is turned off. The diaphragm pump 2 is started and voltage is applied to the two-chamber diaphragm electrolyzer 3. The pulsation frequency depends on the pressure of compressed air supplied to drive the diaphragm pump, and is 100-200 double strokes per minute, at an air pressure of 4-6 kg / cm ² , respectively. The volume of reaction mass injected for each direct stroke of the membrane pump is 350-500 cm ³ . Accordingly, the same amount is absorbed by the pump in the reverse cycle. This mode of operation of the installation (without supplying a fresh solution) continues until the complete release of dissolved metal is achieved. The release of metal from the solution into the precipitate is judged visually - by the disappearance of the color of the solution in the entire installation. The reduction of metal ions into a metal precipitate occurs after 5-50 minutes of operation of the unit without supplying a fresh solution. After complete discoloration of the entire volume of the solution in the installation, the supply of fresh solution begins. To do this, the metering pump 1 is turned on. The volume of the supplied solution is established by the criterion: the absence of color of the solution in the last loops of the multi-pass reactor and damping tank. Removal of the precipitate of the obtained metal is carried out through the metal selection device 8. The criterion for the start time of the selection of the obtained metal is the appearance of a black precipitate of the reduced metal above the 10-12th circuit. To remove the accumulated metal, a hose valve 8 is opened. Metal in the form of a compacted precipitate is squeezed out into a receiving tank.

The bleached solution from the damping tank 9 is sent to the polymer tank and is subsequently used to prepare fresh metal solutions.

For examples 1-3, a solution was used coming from the industrial leaching operation, that is, the dissolution of palladium from spent alumina catalysts of the APK-2 series. The technological solutions in the above examples differed only in the content of palladium dissolved in them (table 1).

Table 1 Solution component Example 1 Example 2 Example 3 Content (g / l) Palladium (Pd ⁺² ) 1.0 3.0 5.0 Free HCl 200-210 Hydrogen peroxide 20-25 Technological parameters Electrolyzer Voltage (V) 18-22 Amperage (A) 14-18 The number of "starting" mobile (g) 150

In each of examples 1-3 of the operation of the installation, the technological flow rate (feed rate) of the solution for processing from the peristaltic metering pump 1 was determined.

The absence of dissolved palladium (completeness of extraction) was determined throughout the working day by the installation operator - visually, by the absence of color of the solution. In parallel with the visual, every 60 minutes at point 6, samples were taken from the purified solution and analytical control for the content of palladium.

The time period of work for the calculations according to these examples was adopted as the working shift of the operator of the production site - 6 hours of operational time of the pilot plant.

The actual results of the installation in Examples 1-3 are shown in table 2.

table 2 The content of Pd ⁺² (g / l) Unit operation time (min) Recycled Solution (L) Solution Flow Rate (L / h) Received palladium in metal (g) Example 1 1.0 306 290.5 0.95 289.2 Example 2 3.0 340 211.0 0.62 621.4 Example 3 5.0 300 91.6 0.31 450.7

Based on the actual data on the operation of the installation by the proposed method, technological indicators were calculated. The calculation data are shown in table 3.

Table 3 The content of Pd ⁺² (g / l) Unit operation time (min) Received palladium in metal (g) The rate of extraction (deposition) of palladium in the installation (g / min) Example 1 1.0 306 289.2 0.95 Example 2 3.0 340 621.4 1.83 Example 3 5.0 300 450.7 1,50

After completion of work, analytical control of solutions for the content of palladium is carried out. The results of the analysis of the solutions for examples 1-3 are shown in table 4.

Table 4 Analytical residual Pd ⁺² in solution after precipitation (g / l) Solution Volume (L) Mass Pd ⁺² in the solution returned to production (g) Example 1 0,027 290.5 7.83 Example 2 0,039 211.0 8.23 Example 3 0,041 91.6 3.76

For example 4, we took a solution of nickel chloride, similar in composition to the standard solution of chemical nickel used in electroplating.

As a reduction catalyst, finely dispersed nickel obtained by a known method by reduction of nickel hydroxide with hydrogen was used.

Table 5 shows the composition of a standard chemical nickel electrolyte and the composition of the solution processed by the proposed method.

Table 5 Standard electrolyte amount The electrolyte according to the proposed method Nickel chloride (11) - g / l twenty twenty Sodium acetic acid - g / l fifteen no Thiourea - g / l 0,03 no Sodium hypophosphite - g / l 25 no Nickel metal (black) no 200 g Temperature ° C 90 23 Hydrochloric acid to pH 4.0-5.0 4.0-5.0

As can be seen from the table, in contrast to the standard solution of chemical nickel plating, a solution containing no reducing agent — sodium hypophosphite — the main one for these processes, was sent to the nickel metal. Substances - stabilizers and pH regulators were also excluded from the solution.

The launch and implementation of the process were carried out according to the general methodology.

Technological parameters of the installation in example 4 are shown in table 6.

Table 6 Technological parameters Electrolyzer Voltage (V) 12 Cathode current strength (A) 9-15 The number of "starting" mobile (g) 200 Diaphragm pump operating frequency (Hz) 2.5

The time before the “start” of the recovery reaction in the instant discharge mode was 46 minutes. After the discharge of the solution, the supply of fresh portions for recovery began. The volumetric feed rate was determined by the “absence of green color” of the solution at the outlet of the installation.

The values of the volumetric feed rate for the entire time of work on the selection of metal are shown in table 7.

Table 7 The time from the start of the solution (min) Volumetric feed rate (dm ³ / min) one 0.20 four 0.20 10 0.40 12 0.20 25 0.40 60 0.50 90 0.45 120 0.50 180 0.50 240 0.50 300 0.50

During one work shift, the entire prepared nickel chloride solution was processed. Technological results are shown in table 8.

Table 8 Indicator Food amount Unit operation time min 300 Recycled solution dm ³ 135 Nickel precipitate obtained g 2812.5 Nickel content in the processed solution g / l 0.94 _residual Nickel release rate g / min 9.38 The purity of the obtained Nickel % wt. 98.6

The results of the experiment in example 4 showed that the purity of the metal obtained is higher than that obtained by known chemical reduction methods, since the added reducing agent does not introduce foreign substances into the metal, as for example in the case of hypophosphites, when the metal contains up to 2-5% phosphorus .

One of the main pollutants of precipitated metals are alkaline earth and transition metals present in solutions, for example: Ca, Mg and similar properties. The transfer of solutions to the alkaline region automatically entails the transition of these impurities into a difficultly soluble state.

Thus, on the basis of the results obtained in examples 1-4, it can be stated that the ability to work in the range of acidic and neutral solutions, according to the proposed method, can guarantee to leave these metals in solution and prevent their coprecipitation with the target product. This significantly increases its purity, since it is these elements that contribute the maximum gross pollution in the production of pure metals.

Actually, the content of calcium impurities in palladium, when precipitated by a known method: reduction with sodium alkali formate (control experiment) and according to the method proposed in this invention, changed from 0.026% wt. up to 0.002% wt.

That is, by the impurity of this element, the resulting metal has become an order of magnitude cleaner.

In General, the proposed according to this invention, the method greatly reduces the sensitivity of the process to the composition of the processing solutions. The method is more universal, the pH of the medium, the presence or absence of contaminants has little effect on the performance and purity of the resulting metal.

During the operation of the installation, only two types of energy carriers are consumed: compressed air to drive the diaphragm pump and electricity (direct current low voltage) to power the cell.

Thus, the main advantages of the proposed method is the simplification of the process of metal separation from solutions due to the rejection of a large number of reagents, the environmental friendliness of the process, the continuity and cyclicity of the process and, as a result, the absence of production discharges, as well as the purity of the metal obtained.

Claims (10)

1. The method of separation of hydrogen-absorbing metals from solutions, including the stage of metal reduction, characterized in that the reduction is carried out by the solution generated by hydrogen, the reduction is catalyzed by the reduced metal itself in a highly dispersed state, and the reduction is carried out in a multi-pass reactor under variable pressure, which vary with a frequency of 1-5 Hz from maximum to minimum values from 8 kg / cm ² to 0.25 kg / cm ² . 2. The method according to claim 1, characterized in that the metals capable of absorbing hydrogen are metals selected from the group consisting of palladium, platinum, nickel, cobalt, ruthenium, rhodium, gold, iron and titanium. 3. The method according to claim 1, characterized in that the variable pressure in the multi-path reactor is provided as a result of the reciprocating movements of the solution created by the modified volumetric pump. 4. The method according to claim 1, characterized in that the multi-path reactor is a system of series-connected loops, each loop consisting of alternating straight sections going to the right and left of the junction of the loops and sharp turns. 5. The method according to claim 1, characterized in that hydrogen is generated in solution using an electrolyzer with a separated cathode and anode space. 6. Installation for the allocation of capable of absorbing hydrogen metals from solutions by the method according to one of claims 1 to 5, including:
dosing device
modified volumetric pump,
an electrolyzer for generating hydrogen;
multi-pass reactor
however, it is made with the possibility of creating reciprocating movements of the solution and variable pressure using a modified volumetric pump and a multi-way reactor in the form of a maze. 7. Installation according to claim 6, characterized in that it is configured to change the pressure with a frequency of 1-5 Hz from maximum to minimum values from 8 kg / cm ² to 0.25 kg / cm ² . 8. The installation according to claim 6, characterized in that the multi-path reactor in the form of a labyrinth is a system of series-connected loops, each loop consisting of alternating straight sections going to the right and left of the junction of the loops and sharp turns. 9. The installation according to claim 6, characterized in that it is configured to manually adjust the flow of the solution by the metering device. 10. The installation according to claim 6, characterized in that it further comprises a device for determining the residual content of the recoverable metal in the solution based on the optical sensor and regulation based on this supply of the solution by the metering device.

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