SU1346697A1 - Method of obtaining copper powder by electrolysis - Google Patents

Abstract

The invention relates to powder metallurgy, in particular, to methods for producing copper powder by electrolysis. The purpose of the invention is to obtain a powder with a bulk density of 2.0-2.8 g / cm and a flowability of not less than 1.06 g / s. Copper powder is produced by electrolysis from sulphate electrolyte with a continuous build-up of sediment at the cathode and changing at a rate of 300-405 A / m h current density from the minimum, exceeding the limiting diffusion current density in a fixed electrolyte of the selected composition 4-6 times, to the maximum, located in the range of 1700-4000 A / m. with f when bubbling air with its flow rate of 5.45-29.45. 5 tab. / L SB 05 05 co

Description

one

The invention relates to powder metallurgy, in particular, to methods for producing copper powder by electrolysis.

The aim of the invention is to obtain a powder with a bulk density of 2.0-2.8 g / cm and a flowability of not less than 1.06 g / s.

An electrolyte of the following composition is poured into the electrolysis bath, g / l: Anhydrous copper sulphate40 Sulfuric acid 140 A cylindrical copper cathode with a diameter of 1.2-10 m and two copper anodes hang at the bath when the ratio of the working surface of the cathode and anodes is 1:12. A current is applied to the cell, providing a linear change in the cathode current density from 1400 to 2900 A / m at a speed of 300 A / m h for 5 hours. The initial current density of 1400 A / m exceeds the limiting current density determined in the absence of mixing for the electrolyte of the selected composition 4 times (inp 350 A / m). Bubbling is carried out with air flow.

cathode surface

5.45 for 1 st.

The results of the experiments are summarized in table. one .

A comparison is made of the results of an experiment conducted in a well known way.

As can be seen, the electrolysis according to the proposed method ensures the production of copper powder with increased bulk density and good flowability with a long build-up of powder on the cathode.

The substantiation of the limits of the change in the speed of the current setting, the speed of the bubbling, the final current density and the initial current density are respectively given in Table. 2-5.

As shown in the table. 2, a slow increase in current (test 1, the rate of current rise is less than 300 A / m-h) lags behind the development of the sediment growth front, which leads to the reduction of diffusion limitations and the formation of coarse compact particles with a bulk density greater than 3.5 g / cm

A current sweep at a speed of more than 430 A / m-h causes dendrites to be intensively drawn in lengths and

thirty

ots

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results in a fine loose sediment with low bulk density (less than 2 g / cmM.

In the absence of bubbling (Table 3, experiment 1), the limiting diffusion current density and the corresponding dendrite thickening rate are too small to form

10 large massive dendrites, the bulk density of the powder is small, the aim of the application is not reached. Too intense sparging (more than 29.45 m / m h) causes such a 15 mixing of the near-electrode space, at which the rate of thickening of the dendrites becomes unacceptably large and leads to the formation of coarse particles with bulk density

20 3 g / cm and can lead to the formation of a solid metal on the electrode.

The choice of the upper value of the current density is justified by the data in Table. 4. The current rampage to a current density of less than 1700 A / m causes too short a period of build-up of loose sediment, which does not provide ease of maintenance of the electrolyzer. The rise of the current to the current density of CBbmie 4440 A / m leads to an intensive release of hydrogen, additional mixing of the near-cathode space. The complete removal of diffusional restrictions creates the conditions for the formation of coarse compact particles with a bulk density greater than 3 g / cm, i.e. does not ensure the achievement of the aim set forth in the application.

The initial current density should exceed 4-6 times the limiting one (Table 5). Initial current density

40

less than 4 i pr does not create in the cathode

the depletion space is sufficient to form a branched dendritic sediment; coarse particles with a bulk density of more than 3 g / cm are formed on the cathode (test 1); such a sediment is covered with a crust of a compact metal; no dendritic powder is obtained. The initial current density, which exceeds the limit by more than 6 times, narrows the interval of sediment buildup to a period of less than 2 hours, which makes it difficult, compared to the basic object, to maintain the electrolyzer,

Using the proposed method of obtaining copper powder

It provides the following advantages by trolysis: the ability to control the bulk density of the powder within 2, P - 2.8 g / cm depending on the electrolysis conditions; obtaining copper powder with good fluidity; maintaining a long, more than two hours period of continuous build-up of loose sediment without removing it, which facilitates the maintenance of the electrolysers.

Claims (1)

Invention Formula A method for producing copper powder by electrolysis from a sulfate electrolyte, which includes a linear change in current over time with a continuous build-up of sediment on the cathode, about the fact that, in order to obtain a powder with a bulk density of 2.0-2.8 g / cm and the fluidity is not less than 1.06 g / s; electrolysis is carried out at a variable speed of 300-405 A / m-h current density from the minimum, which exceeds the limiting diffusion current density in the fixed electrolyte of the selected composition by 4.6 times, to the maximum - dashe in the range of 1700-4000 A / m, with a bubble e air with its flow rate 5,45-29,45. 4 1344/336 4.42 4 1220/305 2.3 4 1344/336 2.2 4 1400/350 2.1 4 1080/240 3.0 Table 1 0 five 0 5 g Cathode density, A / m Concentration copper, g / l Current sweep speed The interval of removal of the powder, h 1400-2900 480-4545 sixteen 300 5.0 Bundled raft. ness, g / cm 2,8 Fluidity (50 g of powder), 33 I l Sparging, m / m -h 5.45 sixteen 2000 2.03 0.7 Not flowing -) Bulk density is determined after screening the + 315 fraction. table 2 Table 3