RU2332526C2 - Method of preparation of chlormagnesium raw material to electrolytic production of magnesium and device for therefor - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to non-ferrous metallurgy, particularly to method of preparation of chlormagnesium raw material to electrolytic production of magnesium and to device therefor. The method includes charging of chlormagnesium raw material with contents of not less than 95% of MgCl₂, mixing it with spent electrolyte or slime-electrolyte mixture from electrolysers of individual feeding with contents of MgCl₂ from 3.5 to 7% and gravity cleaning of mixture from impurities. The ratio of volumes of mixed melts is maintained equal to 1:0.9-1:1.2, and produced melt containing 48-52% of MgCl₂. The device is made as a lined reservoir covered with a ceiling, the said reservoir being divided, by means of partition, into two chambers: a chamber for mixing of chlormagnesium raw material with spent electrolyte of electrolysers of individual feeding or slime-electrolyte mixture, and a chamber for sediment of ready melt equipped with overflow apertures in the dividing partition. The device is equipped with a projecting filling facility for melt pouring with an input horizontal branch, with the upper edge thereof located below the minimal level of melt in the mixing chamber. The projected filling facility and the mixing chamber are separated by means of partition providing a hydraulic lock.

EFFECT: upgraded quality of raw material, increased power yield on electrolysers, reduced volume of production wastes due to utilisation of spent electrolyte and slime-electrolyte mixture of electrolysers.

8 cl, 1 dwg

Description

The invention relates to non-ferrous metallurgy, in particular to an electrolytic method for producing magnesium from a mixture of chloromagnesium raw materials with spent electrolyte or a sludge-electrolyte mixture from electrolyzers with a lower input of anodes and to a device for its preparation.

A known method of producing magnesium and chlorine in a production line from raw materials obtained by diluting magnesium chloride saturated anhydrous carnallite with a reverse electrolyte (O. A. Lebedev. Production of magnesium by electrolysis. M .: Metallurgy, 1988. - p.227). The preparation of enriched electrolyte, which circulates in the production line, is carried out in an intermediate tank in the head of the stream. In this tank, the circulating electrolyte is mixed with carnallite until a melt with 20-23% MgCl _{2 is} obtained.

The disadvantage of this method of producing magnesium and chlorine and a device for the preparation of raw materials are:

- the need for electrochemical purification of raw materials after mixing in special units (refining electrolyzers),

- increase in specific energy consumption for magnesium production,

- quick wear of the electrodes in the units for the preparation of raw materials,

- a large amount of solid sludge in refining electrolyzers, which is removed manually,

- use only anhydrous carnallite as a raw material.

A known method of producing magnesium and chlorine in a production line and a production line for its implementation (Vetyukov M.M., Tsyplakov AM, Shkolnikov S.N. Electrometallurgy of aluminum and magnesium. Textbook for high schools. - M .: Metallurgy, 1987 - with .304-305), including centralized loading of raw materials, mixing it with an electrolyte up to 20-24% in an aggregate for preparing raw materials and electrochemical and gravitational cleaning of the melt in refining electrolyzers. The disadvantages of this method of producing magnesium and chlorine are:

- low content in the prepared melt MgCl ₂ ,

- insufficiently complete cleaning of the melt in the refining electrolyzer from impurities due to the constant circulation of the electrolyte,

- increased power consumption and graphite,

- short service life of the unit for the preparation of raw materials.

A known method of producing magnesium and chlorine, a production line for its implementation and its parts, taken as a prototype (RF Patent No. 2128730, C25C 3/04, publ. 04/10/1999, Bull. No. 10), including a method for producing magnesium and chlorine in the production line, the production line and its units. Raw materials are prepared in the unit for the preparation of raw materials, consisting of a chamber for mixing raw materials with a circulating electrolyte, a sludge chamber and a sludge-electrolyte mixture processing chamber. Next, the enriched electrolyte enters the unit for electrochemical treatment, consisting of an electrochemical treatment chamber and an electrolysis chamber, separated by a partition with transfer windows.

The disadvantages of this technology are:

- the inability to use raw materials with a high MgCl ₂ content due to significant heat release when it is poured into the mixing chamber in an amount calculated for all electrolyzers of the supply line,

- large mass flows of the prepared melt due to the low content of MgCl ₂ in it,

- additional costs of direct current electricity for electrochemical cleaning of the melt,

- to maintain the required temperature in the processing chamber of the sludge-electrolyte mixture requires the use of additional heated electrodes and transformers feeding them with alternating current.

A known unit (head mixer), adopted for the prototype, the working space of which is divided by a partition into two chambers: in the first, the recycled spent electrolyte is mixed with anhydrous carnallite, and in the second, the obtained melt is purified by settling of magnesium oxide and other solid suspensions. The cameras are equipped with electrodes (M.A. Eidenzon. Metallurgy of magnesium and other metals. M: Metallurgy, 1974 - S. 157-159).

The disadvantages of this unit are:

- the inability to use raw materials with a high content of MgCl ₂ ,

- short life due to the large wear of the electrodes,

- insufficient purification of the melt from impurities in the head mixer due to the circulation of the electrolyte,

- the need to use the unit for electrochemical cleaning of the melt,

- the inability to use to power the cells in an individual mode.

The aim of the present invention are:

- the use of raw materials based on chloromagnesium raw materials with a content of at least 95% MgCl ₂ for powering electrolyzers with a lower input of anodes,

- improving the quality of raw materials prepared for the electrolytic production of magnesium and chlorine,

- increase current efficiency,

- reduction in specific energy consumption,

- reduction of mass flow due to the production of raw materials, more concentrated on magnesium chloride,

- reduction of magnesium production wastes under an individual maintenance regimen.

The problem is solved in that in the method of preparing raw materials for the electrolytic production of magnesium, consisting of loading chloromagnesium raw materials, mixing them with spent electrolyte or sludge-electrolyte mixture, gravitational purification from impurities, it is new that, as the starting raw materials, chloromagnesium raw materials with a content of not less than 95% MgCl ₂ , spent electrolyte or sludge-electrolyte mixture of magnesium individual electrolysis cells, with an MgCl ₂ content _of from 3.5 to 7%. Moreover, the volume ratio of the molten melts is maintained equal to 1: 0.9-1: 1.2 to obtain a mixture with a content of 48-52% MgCl ₂ .

To implement the method, a device is proposed for preparing raw materials for the electrolytic production of magnesium and chlorine, which is a mixer made in the form of a lined container covered by a ceiling and divided by a partition into two chambers: a chamber for mixing chlorine-magnesium raw materials with spent electrolyte of individual power electrolyzers or a sludge-electrolyte mixture and a ready-made sludge chamber melt with overflow windows in the dividing wall, with a remote filling device for pouring melt from the inlet mountains zontally made pipe, the upper section of which is below the minimum level of the melt in the mixing chamber, wherein a tanker casting device and the mixing chamber are separated by a partition providing the water seal.

In addition, the remote filling device is equipped with a sealed lid and has a sanitary-technical suction.

In addition, at least two pairs of transfer windows in the dividing wall between the chambers are made at two levels: the upper ones communicate the gas spaces of the chambers and are buried in the melt at a minimum level of 50-70 mm, the top of the lower windows are below the minimum level by 150 mm s even distribution of pairs of windows along the width of the mixer.

In addition, openings with covers were made in the ceilings of the chambers to remove sludge with a grab and pump out the finished melt.

The drawing shows a longitudinal section of a device for preparing raw materials.

The device for the preparation of raw materials is made in the form of a two-chamber mixer, it is a lined container 1 closed by overlapping, divided by a partition 2 with transfer windows 3 into two chambers: a mixing chamber 4 and a sludge chamber of the finished melt 5. A remote filling device 6 with a sealed lid is provided for pouring the melts 7 and by sanitary-suction 8. The portable filling device 6 and the mixing chamber 4 are separated by a partition 9 providing a water seal. The pipe 10 of the remote filling device 6 is made horizontally, and its upper cut is below the minimum melt level in the mixing chamber. The overflow windows 3 in the separation wall 2 are made on two levels: the upper ones communicate with the gas spaces of the chambers and are buried in the melt at a minimum level of 50-70 mm, the upper windows are lower than the minimum level by 150 mm with a uniform distribution of the pairs of windows along the width of the mixer. To remove sludge with a grab and pump out the finished melt in the ceilings of the chambers, openings with covers 11 were made.

An example of the operation of the device.

Highly concentrated MgCl ₂ (not less than 95%) raw materials (for example, titanium production magnesium chloride return), spent electrolyte or sludge-electrolyte mixture from individual power electrolyzers with a content of 3.5 to 7% MgCl _{2 are} poured into a remote filling device 6 in the ratio 1: 09-1: 1,2. The ratio of the components 1: 09-1: 1.2 is optimal in terms of technology: with a ratio of less than 1: 0.9, a significant increase in the temperature of the melt in the mixing chamber occurs as a result of an exothermic complexation reaction. With a ratio of more than 1: 1.2, production waste increases.

The poured melts through the pipe 10 flow into the mixing chamber 4. The horizontal inlet pipe 10 of the filling device prevents the sludge from rising in the mixing chamber 4. The water lock of the filling device provides a hermetic filling of the chloromagnesium raw material with a decrease in its hydrolysis, which increases the quality of the finished melt, increases the productivity of electrolyzers, reduces the amount sludge.

Placing 2 transfer windows 3 on two levels in the dividing wall will provide a better exchange of melts between the chambers without stirring up the sludge, which will also favorably affect the quality of the finished raw material.

From the mixing chamber 4 through the opening 11 in the mixer overlap with a grab, the accumulated sludge is periodically removed.

From the melt sludge chamber 5, through the opening 11, a finished melt with a content of 48-52% MgCl _{2 is} pumped out using a vacuum ladle for the electrolytic production of magnesium and chlorine.

Thus, the proposed technical solution for the preparation of raw materials for the electrolytic production of magnesium and chlorine allows you to:

- improve the quality of raw materials,

- increase current efficiency on electrolyzers by 2-3%

- reduce specific energy consumption by 340-500 kW · h / t Mg,

- use electrolyzers with a lower input of anodes for the production of magnesium from magnesium chloride of titanium apparatus

- Dispose of spent electrolyte or sludge electrolyte mixture from electrolysis cells, reduce the loss of valuable components and production waste, reduce raw material consumption.

Claims (8)

1. The method of preparation of raw materials for the electrolytic production of magnesium and chlorine, including the loading of chloromagnesium raw materials, mixing them with spent electrolyte or sludge-electrolyte mixture, gravity purification from impurities, characterized in that the source of raw materials is chlorinated magnesium with a content of not less than 95% MgCl ₂ , spent electrolyte or sludge-electrolyte mixture of magnesium electrolysis cells of individual nutrition with MgCl ₂ content from 3.5 to 7%. 2. The method according to claim 1, characterized in that the ratio of the volumes of the mixed melts of chloromagnesium raw materials and spent electrolyte or sludge electrolyte mixture is maintained equal to 1: 0.9-1: 1.2. 3. The method according to claim 1, characterized in that the mixing is carried out to obtain a melt containing 48-52% MgCl ₂ . 4. A device for preparing raw materials for the electrolytic production of magnesium and chlorine, which is a mixer made in the form of a lined container covered by overlap, divided by a partition into two chambers: a chamber for mixing chlorine-magnesium raw materials with spent electrolyte of individual power electrolyzers or a sludge-electrolyte mixture and a ready-made sludge chamber melt with overflow windows in the dividing wall, characterized in that it is equipped with a remote filling device for pouring the melt with an inlet horizontal a perfectly made pipe, the upper cut of which is below the minimum melt level in the mixing chamber, while the remote filling device and the mixing chamber are separated by a partition providing a water seal. 5. The device according to claim 4, characterized in that the remote filling device is equipped with a sealed cover. 6. The device according to claim 4, characterized in that the remote filling device has a sanitary suction. 7. The device according to claim 4, characterized in that at least two pairs of transfer windows in the dividing wall between the chambers are made at two levels: the upper ones communicate the gas spaces of the chambers and are buried in the melt at a minimum level of 50-70 mm, the lower ones - below the minimum level by 150 mm with a uniform distribution of pairs of windows along the width of the mixer. 8. The device according to claim 4, characterized in that in the ceilings of the chambers there are openings with covers for removing sludge with a grab and pumping out the finished melt.