RU2828379C1 - Hydrothermal method of recycling spent chemical current sources (ccs) - Google Patents

Abstract

FIELD: processing of secondary raw materials.

SUBSTANCE: invention can be used in recycling waste mixture containing manganese-zinc, alkaline, cadmium-containing and lithium-containing chemical current sources (CCS). Method involves mechanical grinding of the waste mixture in disintegrators equipped with flat knives. Leaching of mechanically crushed CCS in vibrating mills of wet grinding in presence of water with temperature of 50–60 °C to form a solution containing ammonium chloride, zinc dichloride, potassium hydroxide, and a leached product, which is thermally treated in cupolas.

EFFECT: provides for high efficiency, ecological safety of utilization of the spent mixture using the known widely used industrial equipment.

4 cl, 5 dwg, 1 tbl, 3 ex

Description

The invention relates to the field of recycling secondary raw materials and can be used in the disposal of waste mixtures containing manganese-zinc, alkaline, cadmium-containing and lithium-containing chemical current sources.

Analysis of patent information

A method for recycling electric batteries, printed circuit boards with radio components and elements of electronic circuits (SU 1621818 A3) is known, in which an undisassembled mixture of batteries and elements is subjected to pyrolysis at a temperature of 450…650°C, the slag is treated with hydrofluoroboric acid with subsequent electrolysis of the liquid substance and separation of the precipitated materials. The pyrolysis gas is burned.

Disadvantages of the known method:

- there is no operating industrial equipment suitable for implementing the invention;

- expensive hydrofluoroboric acid is used;

- pyrolysis at a temperature of 450…650°C, which does not promote the evaporation of non-ferrous metals;

- the burned pyrolysis gas contains chlorine, nitrogen toxins and requires thorough cleaning.

A method for recycling spent chemical current sources is known (RU 2164955 C1), which includes crushing, roasting of raw materials, magnetic separation, acid leaching followed by electrolysis, deposition of zinc on the cathode, and manganese dioxide on the anode.

Disadvantages of the known method:

- there is no operating industrial equipment suitable for implementing the invention;

- a narrowly focused invention designed for the utilization of only “manganese-zinc” systems;

- there is no provision for the disposal of chlorine-containing salts contained in “manganese-zinc” chemical fuels.

A method for processing spent salt and alkaline batteries is known (RU 2763076 C1), including grinding, heat treatment of the ground mass, leaching in an alkali solution, cathodic deposition of zinc from an alkali solution, and removal of chlorides from the solution. Heat treatment of the ground mass is carried out at temperatures from 500 to 800°C for up to two hours, using sodium peroxide as an oxidizer, the consumption of which is up to 65% of the dry mass.

Disadvantages of the known method:

- lack of operating industrial equipment suitable for implementing the invention;

- the use of large quantities of an expensive, toxic product - sodium peroxide.

A Japanese method of recycling used current sources is known (JP61-261443). The method includes crushing the elements and calcining at temperatures from 400 to 1000°C for three hours, during which combustible materials (paper, carbon rods, graphite, soot, plastics, starch, resins) burn. The calcined mass is crushed again, extracting the metal scrap. The powder is treated with hydrochloric acid. The solution contains manganese, zinc, iron, brass. The solution is neutralized with ammonia water. The dissolved elements are extracted by chemical methods.

Disadvantages of the known method:

- a long-term, energy-consuming process that negatively impacts productivity;

- an oxidizer (air) is required to burn combustible components, but how it is used is unknown;

- combustion products of flammable substances are toxic, no harm suppression is provided.

A method for processing the electrode mass of negative electrodes of nickel-cadmium-iron alkaline batteries is known (RU 2015101917 A), which includes leaching cadmium hydroxide with a solution of sulfamic acid at a temperature of 25...95°C, washing and drying it, followed by calcination at 540...610°C. Disadvantages of the known method:

- there is no existing industrial equipment suitable for implementing the known method;

- the production process ends with the production of cadmium oxide, since the method for obtaining metallic cadmium does not provide for a reduction process, which requires the use of carbon or carbon oxide;

- the known method is designed to use a significant amount of sulfamic acid, which complicates the process due to its toxicity and requires environmental protection;

- a multi-operation, labor- and energy-intensive method is limited to the sole extraction of cadmium oxide, sending the remaining mass of batteries, which has material and commercial value, to production waste.

A method for recycling lithium-containing waste (RU 2108644 C1) is known, related to the field of electrochemistry, including the operation of preliminary mixing of lithium-containing waste with higher alcohols: n-butyl, sec-butyl or amyl. The product of lithium extraction from waste is lithium carbonate.

Disadvantages of the known method:

- the known method does not provide for obtaining metallic lithium from lithium carbonate;

- the known method uses reagents belonging to hazard classes II and III, but does not regulate environmental protection measures.

A method for recycling spent current sources (RU 2723168 C1) is known, adopted as a prototype, including crushing the elements with subsequent heating to temperatures from 850 to 1200°C to obtain gaseous, solid and liquid (melt) phases. The gaseous phase contains zinc vapors, which turn into crystallized metal upon cooling. After removing the gaseous phase, the solid and melt are heated to 1400°C, ensuring the restoration of manganese.

Disadvantages of the known method:

- lack of industrial equipment suitable for implementing the invention;

- the scope of application of the invention is limited to manganese-zinc systems;

- vaporized zinc is easily oxidized; the known invention does not provide for measures to prevent oxidation of zinc vapor;

- the reduction of metallic manganese is possible only in the presence of a strong reducing agent, for example, amorphous carbon (charcoal), graphite rods, weak reducing agents contained in elements.

A method for processing a mixture of batteries (CN 102110825 A), adopted as a prototype, is known, including the following stages:

- classification and fermentation of waste;

- removal of carbon rods;

- dissolution of the remaining substances;

- adding sulfuric acid and re-dissolving;

- washing out the remaining substances;

- incineration of filtered sediment.

This is how harmful products are eliminated.

Disadvantages of the known method:

- the extracted carbon rods found no use at the first stage of processing;

- low productivity of the process with significant consumption of hydrochloric and sulfuric acids, sodium hydroxide and ammonia water;

- extraction of valuable non-ferrous metals is not provided.

An analysis of patent information since 2001 under IPC: C22B 3/04, 7/00, 9/00, 19/00 showed that the dominant number of technical solutions for the disposal of chemical waste include the following operations: grinding, magnetic separation, leaching, hydrolysis, heating. The declared technical solutions are not associated with existing, real technological equipment suitable for implementation, are characterized by significant labor and energy costs with a relatively low productivity of the disposal process, and have a negative impact on humans and the environment.

The purpose of the claimed invention is to create a highly productive, environmentally safe method for recycling a waste mixture containing manganese-zinc, alkaline, cadmium-containing and lithium-containing chemical current sources using known, widely used industrial equipment.

The technical result consists in achieving the set goal.

The technical result is achieved in that the method for utilizing the spent mixture containing manganese-zinc, alkaline, cadmium-containing and lithium-containing chemical current sources (CCS) includes mechanical grinding in disintegrators equipped with flat knives, leaching of mechanically ground CCS in wet-grinding vibration mills in the presence of water with a temperature of 50-60°C with the formation of a solution containing ammonium chloride, zinc dichloride, potassium hydroxide, and a leached product, which is thermally processed in cupolas.

In this case, the solution after leaching of the chemical additive is dehydrated, restoring the crystalline structure of ammonium chloride, zinc dichloride, and potassium hydroxide.

In cupola furnaces, an energy carrier is simultaneously produced - generator gas, suitable for use as a gaseous fuel.

The generator gas coming out of the vargan, containing vapors of zinc, cadmium, lithium and mercury, is cooled to produce powders.

The result of using the hydrothermal method of recycling spent chemical current sources: complete liquidation of any types of spent chemical current sources with the production of restored chemically pure crystalline salts, non-ferrous metals for repeated use and manganese conglomerate suitable for use as a microfertilizer and catalyst. In addition, the implementation of the claimed method is accompanied by the simultaneous synthesis of a gaseous energy carrier suitable for use as a gaseous fuel.

The claimed hydrothermal method of recycling spent chemical fuels is explained by the following graphic materials:

Figure 1: Scheme of transformation of any types of spent chemical and information technologies into secondary, in-demand products;

Figure 2: Scheme of a two-stage technological process for the hydrothermal method of recycling spent chemical fuel;

Figure 3: Schematic diagram of the recycling process for used manganese-zinc electrical components;

Figure 4: Schematic diagram of the recycling process for spent alkaline electrical elements;

Figure 5: Technological scheme with elements of the material balance of the process of practical application of the hydrothermal method of recycling spent chemical fuels.

Description of the technological process of the hydrothermal method of recycling spent chemical current sources (CCS)

The hydrothermal method of recycling spent chemical current sources (CCS) is universal, since it can recycle all currently existing types of spent CCS with the return of the CCS constituent elements to their original pristine state, suitable for repeated reuse.

Figure 1 shows a diagram of the transformation of types of spent chemical current sources (CCS) into secondary, in-demand products: salts, hydroxide, non-ferrous metals and manganese conglomerate with a manganese content of more than 80%, which allows it to be used without any additional processing as a microfertilizer or catalyst "Gopcalite".

The hydrothermal method of recycling spent chemical fuels is a two-stage process.

The first stage is leaching, the second stage is thermal extraction of non-ferrous metals from leached CIT.

Figure 2 shows a diagram of a two-stage technological process.

The spent chemical substances received for disposal are passed through a knife disintegrator (a standard disintegrator in which the impact cylindrical fingers are replaced by knives) without any preliminary treatment. The disintegrator is equipped with a flushing device that ensures cleaning of the equipment from sticking of electrode pastes.

A water-solid pulp with a humidity of approximately 50% comes out of the disintegrator and is placed in the chamber of a vibration mill for "wet" grinding. Vibration leaching, together with hot water supplied to the mill chamber, accelerates the process. It has been experimentally established (by the authors) that 96...98% leaching of NH ₄ Cl, ZnCl ₂ , KOH can be achieved in 10...12 minutes of thixotropic action on the processed pulp.

An aqueous solution of leached products with a concentration of at least 15% is sent to a typical industrial crystallizer. Due to the large difference in the solubility of the leached compounds (at t = 50…60°C NH ₄ Cl = 50.2 g; ZnCl ₂ = 470…495 g; KOH = 141.4…147.5 g in 100 g of water), the leaching process occurs quickly and efficiently, yielding crystallized products of high chemical purity.

The leached CHITs are transferred to the second thermal stage of utilization.

Thermal treatment of leached CIT is carried out in two typical industrial devices: an air gas generator or a metallurgical cupola.

The purpose of heat treatment is to evaporate and distill non-ferrous metals from leached CHIT.

Evaporation temperatures of non-ferrous metals (excluding mercury): cadmium 767°C, zinc 910°C, lithium 1350°C.

An industrial gas generator converts solid fuel (wood, peat, coal, etc.) into generator gas with a temperature in the active zone (carbon oxidation) of 1100…1200°C. If the fuel, preferably high-calorific: charcoal or coke, is mixed with leached CIT and this mixture is passed through an air gas generator, then the resulting air generator gas will be enriched with cadmium and zinc vapors, which can be crystallized from the gas substance by cooling in a “wet” scrubber.

The manganese conglomerate from the gas generator will come out in the form of a porous sinter, which is due to the relatively low temperature of heat treatment.

In industrial cupolas with a temperature in the active zone of 1500…1600°C, generator gas is formed as a concomitant by-product of steel and cast iron smelting. If steel and cast iron in industrial cupolas are replaced with leached CHIT, then transformations similar to those described above will occur, supplementing the process with evaporation of high-boiling lithium.

Thus, the second stage of utilization ends with the “decomposition” of the leached CIT into powdered chemically pure metals and manganese conglomerate, which, in comparison with the gas-generator cake, is represented by a melt, which it is advisable to granulate immediately in a water bath by analogy with the melt of the metallurgical process.

For a deeper understanding of the physicochemical processes accompanying hydrothermal transformations in chemical fuels, three examples are given below for the most common manganese-zinc elements and alkaline elements in the world and the Russian Federation.

Examples of practical application of the claimed hydrothermal method of recycling spent chemical fuel

Example 1. Disposal of spent manganese-zinc elements

Initial average composition of waste elements (percentage by weight):

Figure 3 shows a diagram of the technological process for recycling 100 kg of spent manganese-zinc elements.

As a result of mechanical crushing of batteries in rotary-impact mechanisms (hammer mill, disintegrator), crushed elements (working body) are obtained, which are loaded into the drum of a vibration mill, where water heated to a temperature of 50...60°C is pumped. The amplitude of vibrations of the vibration mill should be within 1.2...1.5 cm, the frequency of vibrations is not regulated. The vibration time is determined empirically to achieve a concentration of dissolved NH ₄ Cl and ZnCl ₂ of at least 15% of the aqueous solution, which corresponds to approximately 95% of the leached salts. Approximate composition of the alkaline selection (kg/percent by weight):

Considering the different solubility of salts, it is possible to separate them qualitatively, returning them to the crystalline state by ordinary evaporation.

Since 10.8 kg of physical water accounts for 1 kg of crystalline calcium salts, the predicted energy costs for evaporating 1 kg of salts will be 6830 kcal.

As a result of aqueous hot vibratory grinding leaching of 100 kg of the initial mass, the working fluid will decrease to 80.7 kg, of the following composition (kg/percent by mass):

The working fluid obtained in this way is sent for thermal treatment to the gas generator.

The fuel in the gas generator is charcoal, burned at a temperature of at least 1000°C (to reduce the amount of volatiles and increase the calorific value) with the following approximate composition (percentage by weight):

The calorific value of such fuel is not less than Q=7800 kcal/kg (32.6 MJ/kg);

The working fluid is 80.7 kg, containing its own combustible mass (carbon-containing component) up to 31% in the gas generator mixed with fuel (charcoal). The ratio of the working fluid and charcoal, which guarantees obtaining a temperature of 1100°C in the active zone of the gas generator with a high yield of generator gas is 1:2 (research by the authors).

That is, if the amount of working fluid is 80.7 kg, then the content of charcoal should be:

80.7*2→161.4 kg (carbon 153.6 kg).

To this amount of carbon should be added the working fluid's own carbon - 25 kg.

The total amount of carbon involved in the synthesis of generator gas: 25 kg + 153.6 kg = 278.6 kg.

To obtain air generator gas in the direct process for 278.6 kg of carbon, 1040 kg of air are required. In the active zone of the gas generator, the temperature is about 1000 ° C, the zinc that gets there evaporates and in the form of steam, together with the "raw" synthesized air generator gas of 1229.8 kg, is sent to the condenser for cooling and purification. In the condenser, 3.6 kg of crystallized dispersed zinc powder and 4.9 kg of washed "garbage" fall out. Purified air generator gas in the amount of 1221.3 kg of the following composition (kg / percent by volume) departs:

When washing the “raw” generator gas in the condenser, the following will be released: 0.4 kg HCI (the result of the thermal decomposition of NH ₄ Cl); 0.5 kg ZnCl ₂ .

The water vapor of the generator gas is carried away with the condenser wash water.

The density of commercial air generator gas under normal conditions is 1.25 kg/ ^m3 .

The lower calorific value is 1100 kcal/ ^Nm3 .

The gas generator will produce 50.9 kg of sinter, consisting of (percentage by weight):

Thus, as a result of the complete liquidation of 100 kg of spent manganese-zinc chemical feedstocks, the following were obtained: crystalline products suitable for secondary use (NH ₄ Cl, ZnCl ₂ , Zn); energy carrier (generator gas); manganese-iron cake (microfertilizer, catalyst).

Costs: 160 kg of charcoal and electrical energy, which can be generated independently using generator gas energy.

Example 2. Disposal of spent alkaline electrical elements

Initial composition of waste elements (percentage by weight):

Figure 4 shows a diagram of the technological process for recycling 100 kg of spent alkaline elements.

The grinding and leaching operations are carried out similarly to the process described in Figure 1. However, as a result of leaching with an aqueous solution, only potassium hydroxide will be released. Dehydration of the solution in order to obtain crystalline KOH requires energy costs of up to 3560 kcal per 1 kg of dry KOH.

The leached crushed material weighing 97.7 kg has the following composition (kg/percent by weight):

The thermal stage of the operation is carried out in a cupola. The cupola differs from the air generator only by a device that provides liquid (melt) removal of slag-manganese conglomerate. The maximum temperature in the active zone is 1600°C. But in the cupola it is possible to set lower temperatures, reducing the energy consumption.

The amount of charcoal that provides the required temperature in the active zone is taken from the ratio 1:2 (see figure 3):

97.7*2→194.4 kg (carbon content in charcoal 186 kg).

The amount of carbon in dispersed graphite is 11.2 kg.

The total amount of carbon involved in the synthesis of generator gas is 197.2 kg.

Similar to Example 1, we calculate the amount of blast air for the gasification process, which is 1252.4 kg (970 ^Nm3 ).

As a result of heat treatment in a gas generator with a temperature in the active zone of at least 1000°C, 1473.6 kg of air generator gas was formed, including 14.6 kg of zinc vapor and 66.9 kg of brass-iron-manganese melt.

"Raw" generator gas, passed through a "wet" scrubber, releases 14.6 kg of powdered crystalline zinc, while the amount of commercial air generator gas formed is 1463 kg. The composition and calorific value of the resulting generator gas, close to example 1.

The shown gas generator process can utilize elements and batteries containing cadmium, the evaporation temperature of which is 767°C.

Utilization of electrical sources containing lithium, the evaporation temperature of which is 1350°C, cannot be performed in a gas generator, but high-temperature devices - cupolas - should be used for lithium utilization. In this case, the cake formed in the gas generator process will be represented by a melt in the cupola, which is immediately granulated by draining into a water bath.

Example 3. Organization of an industrial process for the use of a hydrothermal method for the disposal of spent chemical fuels

The solid municipal waste sorting plant (MSZ MSW) has a capacity of 200,000 tons/year for MSW (23 tons/hour).

As a result of sorting, approximately 1.3% of the total mass of MSW was recovered, i.e. 2600 t/year (0.3 t/hour).

Approximate composition of extracted spent chemical substances (percentage by weight/kg per hour):

The thermal part of the utilization is carried out in a cupola with an operating temperature of 1500°C, ensuring the evaporation, in addition to cadmium and zinc, of the most refractory lithium ( _{boiling point} = 1350°C).

The recycling site is equipped with the following standard technological equipment:

- knife disintegrator;

- wet grinding vibratory mill;

- crystallizer;

- cupola furnace;

- "wet" scrubber.

Figure 5 shows a diagram of the technological process of the section with elements of the material balance.

The 300 kg/hour of spent CIT extracted from MSW are passed without sorting through a knife disintegrator equipped with a water wash, which eliminates the adhesion of cathode paste on the knives and prepares the working pulp at a solid + water ratio of 50/50. The water is hot with a temperature of 50…60°C.

The resulting pulp is poured into a wet grinding vibratory mill. Due to the high solubility of the compounds contained in the HIT, the use of a hot solution and the intensification of leaching by thixotropic action, the process occurs quickly, within no more than 15 minutes. The output concentration of the solution must be at least 15%.

Thus, within an hour, 260.2 kg of solid leached product and 265 kg of aqueous solution are formed from 300 kg of mixed crushed assembly of spent chemical fuels, which are passed through a crystallizer to obtain crystalline NH ₄ Cl, ZnCl ₂ , KOH of high chemical purity.

The solid leached product is discharged from the vibratory mill and blown with air for drying (residual moisture no more than 2%), after which it is placed in a cupola furnace, which simultaneously melts and evaporates the ingredients of the chemical additive and synthesizes air generator gas.

The amount of commercial generator gas “kg” is synthesized based on the calculation of the leached product as 1:0.12.

In the example under consideration, to obtain 2690 ^nm3 /hour of commercial gas, it is necessary to use 270 kg/hour of charcoal and 1830 kg/hour of air.

The cupola furnace produces about 2200 kg/hour of “raw” generator gas containing zinc, cadmium, and lithium vapors.

The temperature of the "raw" generator gas is high, not less than 1000°C, with a correspondingly significant enthalpy, and the lithium vapor has already turned into a fog consisting of ultra-dispersed drops of liquid lithium. To obtain crystalline, chemically pure metal powders, their vapors are quickly cooled in a sprayed aqueous medium created by a Venturi scrubber. The thermal energy obtained in this way can be used in the technological process.

The cupola furnace produces a melt of manganese conglomerate with a manganese content of more than 80%.

Table 1 presents the material balance data for the example under consideration.

The technological process of the described section can be fully automated and serviced per shift by three operators.

Claims (4)

1. A method for utilizing a spent mixture containing manganese-zinc, alkaline, cadmium-containing and lithium-containing chemical current sources (CCS), including mechanical grinding in disintegrators equipped with flat knives, leaching of mechanically ground CCS in wet-grinding vibration mills in the presence of water at a temperature of 50-60°C to form a solution containing ammonium chloride, zinc dichloride, potassium hydroxide, and a leached product, which is thermally treated in cupola furnaces. 2. The method according to item 1, characterized in that the solution after leaching of the chemical additive is dehydrated, restoring the crystalline structure of ammonium chloride, zinc dichloride, and potassium hydroxide. 3. The method according to paragraph 1, characterized in that the cupolas simultaneously produce an energy carrier - generator gas, suitable for use as a gaseous fuel. 4. The method according to paragraph 3, characterized in that the generator gas leaving the cupola, containing vapors of zinc, cadmium, lithium and mercury, is cooled to obtain powders.

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