RU2345449C2 - Nickel recovery method from alkaline pocket-plate cell - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to electric engineering and may be used for nickel recovery from the spent alkaline pocket-plate cells. According to the invention nickel is recovered from the spent alkaline pocket-plate cells by dispersing oxide-nickel electrodes and separating nickel-containing mass from lamella fragments. But before oxide-nickel electrodes are dispersed and nickel-containing mass is separated from lamella fragments, the electrodes are initially pre-treated at 270°C during 7 hours, and then at 350°C during 2 hours.

EFFECT: increased rate of nickel recovery from lamella electrode in the spent alkaline battery.

Description

The invention relates to electrical engineering and can be used to extract nickel from spent alkaline batteries of a lamella design for the purpose of its further processing, including the manufacture of an active mass based on nickel nitrate hydrate.

A well-known industrial method of manufacturing the main component of the active mass of nickel oxide electrodes - nickel oxide hydrate (GZN) - from spent alkaline batteries of a lamella design (nickel-cadmium, nickel-iron), based on the use of lamellar oxide-nickel powder as a nickel-containing raw material electrodes, dispersion no more than 2.5 mm. Nickel powder is obtained by crushing and grinding nickel electrodes, after which the powder is purified by magnetic separation to remove the iron component. Nickel recovery in this case is 96%, the remaining 4% of nickel is concentrated in a magnetic product, which is sent to the production of ferronickel.

The composition of the non-magnetic fraction directed to the production of GBV:

nickel (Ni) 33-39 wt.% in the form of nickel oxide hydrate Ni (OH) ₂ , total iron (Fe) - not more than 3 wt.%, impurities of calcium (Ca), magnesium (Mg), silicon (Si).

The composition of the magnetic fraction directed to the production of ferronickel: iron (Fe) 60-80 wt.%; nickel (Ni) 4-6 wt.%

This method is closest to the claimed one and is patented by the patent of the Russian Federation (1).

The disadvantages of this method of extracting a nickel-containing mass from a lamella electrode include:

1. The need to grind the electrodes to a dispersion of not more than 2.5 mm, which requires the use of special equipment and leads to additional contamination of the nickel mass with impurities due to wear on the cutting surfaces;

2. The low degree of extraction of Nickel from a mixture of Nickel powder with a crushed lamella strip during subsequent magnetic separation due to the sticking of the powder on the surface of the lamella.

Description of the invention.

The essence of the invention lies in the fact that to increase the degree of extraction of nickel from the lamella electrode of the spent alkaline battery, the nickel oxide hydrate contained in the electrode is converted to nickel oxide by heat treatment of the electrode by the reaction:

Ni (OH) ₂ → NiO + H ₂ O.

The studies carried out allowed us to establish that during long-term operation of an alkaline lamella battery, the active mass of the oxide-nickel electrode is cemented and, as a result, the mass adheres to the inner rough surface of the lamella.

When grinding a nickel electrode, some of the active mass, due to these reasons, remains on the inner surface of the lamella. So, when grinding electrodes pre-dried at t = 100 ° C with a grinding size of less than 16 mm and subsequent separation of the mixture of powder and pieces of lamella on a screen and magnet, the following results were obtained:

for electrodes with a thickness of 1.2 mm, the degree of separation of 58%;

for electrodes with a thickness of 4.0 mm, the degree of separation of 70%.

The objective of the proposed solution is the maximum separation of Nickel powder from the lamella material.

Oxide-nickel lamella electrodes in the amount of 1000 kg, previously washed in running water from sludge, are placed in a furnace with a set heating temperature on the controller 350 ° C. The power of the heating elements of the furnace is 36 kW. The working volume of the furnace is ventilated. On the rear panel of the furnace there is a damper for removing gases generated during the drying process. When the temperature reaches 230 ° C, water vapor begins to be released from the furnace volume, which is a consequence of the process of thermal decomposition of nickel oxide hydrate with the formation of nickel oxide (NiO) and water. In this case, the temperature growth is slowed down and when it reaches 270 ° С, the temperature remains stable for 7 hours. After that, the intensity of steam evolution noticeably decreases and within an hour the temperature in the furnace rises to a predetermined value (350 ° C). At this temperature, the electrodes are kept for 2 hours, after which the furnace is turned off. After cooling, the electrodes are sent to the NiO extraction unit.

The sequence of operations when feeding the electrodes into the installation:

- grinding of electrodes;

- separation of the fine fraction from the coarse;

- magnetic separation of the finely divided fraction.

The electrodes are supplied to the crushing unit manually. Grinding is carried out by rotating knives, the grinding size is not more than 16 mm.

The ground electrodes are fed by a screw into the rotating drum of the screen. The size of the screening cell is 1.2 mm. At the same time, NiO powder with a certain content of graphite (14-16%) and lamella tape metal (up to 5%) enters the finely dispersed fraction. The lamellar tape material is separated into the coarse fraction. The composition of the separated material of the lamella tape (coarse fraction) is as follows:

- Fe metal, up to 93%;

- NiO no more than 4%;

- C (graphite) up to 2%.

The finely dispersed fraction containing nickel oxide (NiO) is fed from the storage hopper to the magnetic separator by a screw to refine the powder from metal inclusions. At the outlet of the separator, the nickel-containing powder has the following composition:

NiO - 42-52 wt.% For nickel;

C (graphite) - 14-16%;

Fe - up to 2% (including in the form of oxides).

The degree of extraction of nickel from the lamella electrode with the claimed method is at least 99%, which leads to resource savings, to a reduction in the cost of the finished product, nickel oxide hydrate, and does not impair the quality characteristics of the material during its further redistribution.

Information sources

1. RF patent No. 2178931 class. C1 2000.11.08

2. Dasoyan M.A., Novoderzhkin V.V., Tomashevsky F.F. Manufacture of electric batteries. M., "Higher Schooling, 1977.

Claims (1)

A method for extracting nickel from spent alkaline batteries of a lamella design by grinding oxide-nickel electrodes and separating the nickel-containing mass from the lamella fragments, characterized in that before grinding the nickel-oxide electrodes and separating the nickel-containing mass from the lamella fragments, the electrodes are heat treated at a temperature of 270 ° C in for 7 hours, and then at a temperature of 350 ° C for 2 hours