SU1439141A1 - Method of treating waste of lithium and its alloys - Google Patents

Abstract

The invention relates to non-ferrous metallurgy and can be used in the processing of waste of lithium or its alloys. The purpose of the invention is to simplify the processing technology. The goal is achieved by converting lithium into inactive, non-volatile compounds of the composition Li 45104, LiAlOj by heat treating the waste under a layer of sand at 450-500 ° C, followed by cooling. The processed products are sent to the dump. 1 tab.

Description

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The invention relates to the metallurgy of non-ferrous metals and may be used in the processing of waste of lithium and its alloys, which are used in the manufacture of electrodes of chemical current sources.

Lithium and its alloys are characterized with high chemical activity. Lithium decomposes water with hydrogen evolution and the formation of a slightly soluble hydroxide in water. Due to the evolution of hydrogen, there is always the danger of a bump due to the formation of an explosive mixture. When burning waste, thick smoke of alkali metal condensation aerosols, which are highly toxic, is formed. Therefore, the destruction of waste by dissolving in water or burning is unacceptable for production.

The purpose of the invention is to simplify the process technology.

The method consists in transferring waste of lithium or its alloys into inactive lithium compounds by heat treatment of waste under a layer of sand at AZO-ZOO C for 20-40 minutes with a ratio of waste and sand from 1; 30 to 1:60 by weight,

In this case, inactive lithium compounds are formed, which are not dangerous from the point of view of environmental pollution. The process is technological and simple, as it does not require any special equipment, no ventilation cover, or purchased reagents, and sand can be used many times.

The temperature mode is chosen experimentally, since it was found by thermal analysis that the formation of lithium compounds with SiO-2 occurs at 440-442 ° С. The lower limit of the temperature interval reflects the temperature approximately 10 ° C higher than the temperature of formation of compounds taking into account the presence of non-uniform heating of the reaction zone. The upper limit of the temperature range is chosen taking into account the temperature gradient of the furnace. The time of the process is determined experimentally. The mass ratio of the amount of waste and sand is set as follows ;; thermodynamically calculations are made of the heat of reaction for the formation of compounds of Li- and SiO; the amount of heat release is simultaneously checked by calorimetry using a derivatograph. Then

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the mass ratio of sand and waste is selected in such a way that the temperature of the sand at any point does not exceed the auto-ignition temperature of lithium (640 C),

The method is carried out as follows.

Waste of lithium or its alloy is placed in a metal pan, preferably of nickel foil, with rims and poured with sand so that the mass ratio of waste and sand is not less than 1:30. A hot thermocouple junction is placed in the sand layer. The pallet with the products is heated in the furnace up to 450-500 ° C (the reagents are allowed to be heated in the furnace). Further heating of the furnace is impractical, since the heat of the started reaction in one place contributes to heating the entire mass, including ballast sand. After 20-40 minutes, the furnace is turned off, the product is cooled. The full course of the process is judged by the absence of bubbling when the reaction products are placed in water.

The results of the technological method of processing waste under different conditions are given in the table.

Thus, the selected heat treatment mode of 20-40 minutes at a temperature of 450-500 С ensures the completion of the process - the formation of inactive lithium compounds, and the selected mass ratio of waste and sand ensures a safe process.

The proposed method has technical and economic advantages in comparison with the known one, since it does not require complicated instrumentation, it is less energy-consuming, safe and does not pollute the atmosphere, because in its implementation the atmosphere is not polluted with fine aerosols.

Claims (1)

Claims of Invention A method for recycling waste of lithium and its alloys, including heat treatment of waste in the presence of a reagent to form an inactive compound. lithium and cooling, characterized in that, in order to simplify the process technology, heat treatment of lithium waste is carried out under a layer. Sands at 450-500 ° C for 20-40 minutes at a mass ratio of waste and sand 1: 30-1: 60. 1:20 Half past one 1:50 1:50 1:60 1:60 1:50 450 442 500 500 500 550 430 15 Reactions went to the end. According to calculations, the temperature in the reaction zone can reach 770 ° C. In this experiment, the temperature reaches 720 ° C. The amount of sand should be increased. 30 Reactions went to the end. According to the calculation and measurement, the temperature rises to 620 C. A decrease in the ratio of sand and waste is undesirable. 20 The reaction has passed, but there is a slight bubbling when the products are placed in water, i.e. reduce the process time is not possible. The temperature in the reaction zone does not exceed 600 C, 30 The reaction was complete; no bubbles were observed. The temperature in the reaction zone is not more than 600 C, 40 Reactions went to the end. Temperature in the zone reaction does not exceed 530 ° C. It is not advisable to increase the amount of sand due to the irrational use of the furnace space, 50 Reactions went to the end. The temperature in the reaction zone does not exceed 550 ° C. To increase the temperature and time is impractical because of the extra consumption of electricity, energy. 50 Reaction failed.