WO1994011911A1

WO1994011911A1 - Physical and physico-chemical method for processing used batteries

Info

Publication number: WO1994011911A1
Application number: PCT/EP1993/003212
Authority: WO
Inventors: Henri Daester; Donat Guebler
Original assignee: Fairtec Delemont S.A.
Priority date: 1992-11-18
Filing date: 1993-11-16
Publication date: 1994-05-26
Also published as: AU5562994A; EP0679291A1

Abstract

A method comprising physical and physico-chemical steps for processing and recycling used batteries of any shape, size or chemical nature. The physical processing steps comprise turning the batteries into a uniform mass and seprating 35-40 % of the inert residues and directly recyclable metals. The physico-chemical steps of processing the remaining active mass of batteries, i.e. 60-65 % of the overall mass, comprise removing toxic contaminants such as mercury and cadmium, purifying and separating the manganese oxides in the form of a sludge which may be recycled or turned into an inert residue, then purifying and separating the zinc compounds in the form of a metallurgically or electrolytically recyclable hydroxide sludge to obtain metal with a purity of 99.5 % or higher. According to an alternative embodiment of the physico-chemical processing of the remaining active mass of batteries, the zinc is extracted as a directly electrolysable sulphuric solution whereas the manganese oxides and the impurities are turned into granules stabilised by means of an immobilisation method using cement.

Description

PHYSICAL AND PHYSICO-CHEMICAL PROCESS FOR T, F. TREATMENT OF USED BATTERIES AND BATTERIES

INTRODUCTION

In today's industrial society, the use of cells and batteries as a portable energy source becomes a daily gesture. The consumption of these 5 cells and batteries in Western Europe is estimated at 500 tonnes per million inhabitants per year. Unfortunately, after use, these cells and batteries constitute a considerable source of toxic waste because of the heavy metals they contain. For a 10 ton of batteries used by the general public, studies have led to an impressive list of toxic products:

Heavy metals:

Zinc 160 kg / t

Manganese dioxide 270 kg / t

15 Steel 220 kg / t

Mercury 2 kg / t

Copper 20 kg / t

Nickel, Cadmium 10 kg / t

Non-metals:

20 Graphite 60 kg / t

Ammonium chloride, potash 48 kg / t

Water 80 kg / t

Paper, plastic 110 kg / t

Miscellaneous 20 kg / t

*>

.A 25 On examination of this list, the obligation to collect and treat spent cells and batteries imposed by governments is fully justified.

In recent years, manufacturers have invested heavily in research and development of treatment and recycling procedures for used batteries. The objective of these processes is to eliminate toxic contaminants such as mercury and cadmium, to recover recyclable materials such as metals, to stabilize or destroy inert non-recyclable waste such as graphite, inorganic salts, and papers and plastics.

When developing a treatment and recycling process for used cells and batteries, the engineer must take into account two specific aspects of this type of waste:

Used cells and batteries are multicomponent waste, not only by their various chemical natures, but also by the presence of the different materials used in their construction. Therefore, despite sorting the collection or pre-treatment of different types of cells and batteries, the treatment processes must always deal with a mixture of materials and very diverse chemical compounds.

- Used cells and batteries are very heterogeneous mixtures from the point of view of dimensions and shapes. In these mixtures there are blocks ranging from 75x100x200 mm with an average weight of 1000 g to all small units of 3 mm in diameter and 1.5 mm thick weighing just 3 g, passing through all dimensions and all weights intermediaries. This heterogeneity leads to non-uniform physical properties, such as the apparent density or the thermal conductivity.

Used cells and batteries can be treated by a high temperature thermal process (up to 1250 ° C) which consists of removing mercury by distillation, destroying organic and paper components by combustion, and recycling metals by reduction metallurgical. However, the high temperature thermal process has significant drawbacks: - Due to the heterogeneity of the physical properties of the mixture, the treatment may be incomplete locally.

At high temperatures, the presence of chlorinated products and organic components can lead to the formation of very toxic dioxin in the outlet gases.

This process requires a very high investment and energy expenditure.

Used cells and batteries can also be treated by a thermal process at medium temperature (<650 ° C) to remove mercury. The metals are recovered and purified by a subsequent electrolytic process. Here too, the heterogeneity of the physical properties of the mixture can pose a problem of heat transfer during the thermal elimination of the mercury. On the other hand, the chemical composition of mixtures of spent cells and batteries varies from batch to batch. As a result, electrolysis operations cannot take place under constant conditions, and can lead to end products of variable quality.

Finally, the major drawback of these methods is the unnecessary treatment of spent cells and batteries in their entirety, while 30 to 40% of their mass consists of non-toxic materials that can be directly recycled and inert waste.

On the other hand, a heat treatment process at high or medium temperature always presents a potential danger to the environment because of a possible leakage of the outlet gases containing toxic gaseous products such as dioxin, volatile halides of mercury. , cadmium and others. DESCRIPTION OF THE INVENTION

The method for treating and recycling spent batteries and batteries of this invention proposes to overcome these drawbacks, and has the following advantages:

- By adequate physical treatment, the toxic active mass of used cells and batteries is separated from the inactive mass made up of directly recyclable metals and inert waste.

By an adequate physicochemical treatment, the active mass is separated into pure and homogeneous fractions, ready for recovery-recycling.

All the process steps can take place at room temperature, which avoids any potential danger of emission of toxic products into the surrounding atmosphere.

The process for the bulk treatment of used batteries of this invention therefore comprises two treatment stages:

physical treatment which aims to transform cells and batteries of different sizes, shapes and chemical natures into a uniform mass, and to separate a certain amount, usually around 40%, of inert waste or directly recyclable metals.

physico-chemical treatment which aims to eliminate toxic elements from the active mass of cells and batteries, and to purify this mass in recyclable raw materials.

According to the invention, the physical separation comprises at least one grinding and disintegration stage which transforms the cells and batteries into a uniform mass, followed by the mechanical, aerodynamic and magnetic separation stages, which separate the inert residues and the directly recyclable metals uniform mass, leaving a toxic active mass of cells and batteries. Then, this toxic active mass undergoes a physico-chemical treatment in order to provide at least one non-toxic recyclable product.

In a preferred embodiment of the physico-chemical treatment, a selective dissolution-oxidation step making it possible to separate and purify the manganese oxides in the form of recyclable filter-pressed sludge is followed by a step of decontamination of the mercury ions and / or the cadmium and a selective precipitation step to separate and purify the zinc compounds in the form of recyclable filter-pressed hydroxyd mud.

Another preferred embodiment of the physico-chemical treatment comprises a selective dissolution-oxidation step making it possible to separate and purify the manganese oxides in the form of recyclable filter-pressed sludge followed by a selective dissolution combined with cementation of impurities on dust of iron or zinc to obtain a directly electrolyzable zinc sulphate solution, and then stabilization of the manganese oxides with the impurities, by immobilization with a binder such as ^" cement, for final storage.

Other features of the invention are listed in the subclaims.

DESCRIPTION OF THE DRAWINGS

The different stages of the process will be better understood, as well as the flow of material flows with reference to the process diagram given in the attached figures, in which:

Figure 1 is a diagram of a first part of an installation for carrying out the method according to the invention;

Figure 2 is a diagram of a second part of an installation, following the first part of the installation of Figure 1, to carry out this process according to a first execution; and - Figure 3 is a diagram of a second part of another installation, following a first part similar to that of Figure 1, but without the magnetic separator 11, to carry out the method according to another embodiment.

DETAILED DESCRIPTION - PHYSICAL TREATMENT

Separation of the non-toxic fraction from the active mass

At the entrance to the installation of Figure 1, the mixtures of used cells and batteries are discharged into a feed silo 1, from where a worm 2 allows them to be taken at a constant flow rate usually between 0.5 and 1.0 ton per hour. The cells and batteries can be of any chemical nature and of all shapes and sizes.

The cells and batteries are brought by gravity, at this constant flow of 0.5 to 1.0 t / h ensured by a worm

2, in a grinder 3 where they are shredded into more or less uniform pieces of a size between 5 and 30 mm. The most suitable equipment for this operation is a knife mill, consisting of two rows of hard metal cutting discs, rotating in the opposite direction, at a speed between about 20 to 60 revolutions per minute. To avoid the emission of dust, the crusher 3 works in a closed enclosure in which a depression of 10 to 20 millibars is created by connection to a ventilation system (not shown).

At the outlet of the crusher 3, the crushed cells and batteries are in the form of a uniform mixture of pieces with an average size of 10 mm. This mixture is transported by a conveyor belt 4 to a disintegrator 5. The conveyor belt 4 is controlled by an automatic program in order to supply the disintegrator 5 with a load of 20 to 40 kg, for example every 2.5 minutes. As for the crusher

3, the conveyor belt 4 is placed in a closed enclosure, under vacuum, by connection to the ventilation system. The pieces of the crushed cells and batteries are introduced into the disintegrator 5 per load of 20 to 40 kg.

The disintegrator 5 is a special hammer mill, the evacuation and supply of loads of which are controlled by an automatic program.

By the impact of the hard metal masses (hammers) connected to an axis rotating at high speed, between the OOO at 2,000 rpm, the active mass inside the pieces of crushed cells and batteries, as well as brittle materials such as graphite current collectors are disintegrated in the form of fine powders. Similarly, under the action of impacts, button cells of dimensions less than 10 mm, which could not be shredded by the knife mill 3, will be opened to release the active mass inside. The active mass disintegrates by impact, and therefore the crushed pieces of steel containers, copper contacts and paper or plastic envelopes do not suffer damage and keep their initial dimension equal to or greater than 10 mm.

At the bottom outlet of the disintegrator 5 is placed a mechanical separation grid 5 which consists of a steel lattice with an opening of the meshes of 3 to 10 mm, for example. The size of this opening is chosen according to the operational conditions of the grinding, and thus defines the average sizes of the fractions to be separated. This grid 5 'makes it possible to evacuate progressively the powders of disintegrated active mass whose dimension is less than d. The powders thus separated are discharged via a collector 6 for subsequent physico-chemical treatment.

After a determined time, between approximately 2 and 4 minutes, a side door 5 "of the disintegrator 5 opens automatically to evacuate to a worm 7 pieces of metal, paper and plastic, whose size is greater than the opening of the separation grid. A new load is then introduced by the rolling carpet 4 as soon as the 5 "exit door closes automatically.

Separation of directly recyclable metals and inert waste

At the outlet of the disintegrator 5 and of the collector 6, the uncontaminated fraction of the cells and batteries, constituted by the metal pieces of the container, the electrical contacts and the paper or plastic of the envelope, are transported by the worm 7 an aerodynamic separator 7. A constant feed flow d separator, for example between 150 and 400 kg / h, is ensured by the worm 7.

In the separator 8, an appropriately shaped fan, rotating at an adjustable speed, creates an air flow between 500 and 3,000 Nm ^ / h. The particles, sucked in by the air flow, are subjected to three respective forces:

- the driving force of the air flow;

- the centrifugal force due to the circular movement of the air flow; and

- the force of gravity due to the own mass of the particle.

The rest of the powders of the active mass which is not completely eliminated by the mechanical separator 6 is sucked through an upper outlet by the driving force of the air flow towards a bag filter 9.

The pieces of paper and / or plastic, of average size d, between 3 and 10 mm depending on the opening of the grid 6 ', and of density varying between 0.9 and 1.5 g / cm ³ , represent the average mass fraction. This fraction P, subjected to the centrifugal force of the air flow, is projected towards the outside and separated by the cyclone effect, and directed towards a shower installation in closed circuit 23 (Figures 2, 3). The pieces of metal whose density is between and 8 g / cm ³ , undergo a predominant gravity force e fall directly towards a central outlet from where they are directed towards a magnetic separator 10.

At the upper outlet of the aerodynamic separator 8 the air flow, charged with approximately 0.1 to 0.3 g / m ³ of powders of the active mass is directed towards the bag filter 9. The dust, retained by the filter 9, is periodically evacuated by a vibration of the filter assembly, e are added to the fraction of powders leaving the collector 6 for subsequent treatments.

The fraction P of paper and plastic from used batteries, approximately 4 to 10% of the total mass, does not represent any recycling value and will therefore be destroyed by incineration. At the outlet of the separator 8, this fraction of paper and plastic is subjected to an acid wash under oxidizing conditions in order to remove the traces of any toxic element from the active mass of the batteries. The washing is preferably carried out by a closed circuit shower installation 23, with a solution containing from 1 to 5 g / sulfuric acid, and from 1 to 5 g / 1 of potassium permanganate. This solution can be purged periodically, and sent to the mixing reactor 13 (Figure 2) for the periodic treatment. After washing, the mercury and cadmium content of this fraction of inert waste is less than 10 mg / kg (10 ppm). Its destruction by incineration represents no danger to the environment.

At the central outlet of the separator 8, the fraction of metals, approximately 35 to 40% of the total mass, is usually a mixture of iron (75%), copper (7%), nickel (3%), zinc (14%) and other minor elements (<1%). This mixture is directed to a magnetic separator 10 to be separated into a fraction of ferrous metals (30 to 32% of the total mass), and a fraction of non-ferrous metals (4 to 8% of the total mass). These two metal fractions having been freed of any toxic element from the active mass of batteries by separator 8, are recycled as raw materials in foundries.

PHYSICO-CHEMICAL TREATMENT

ALTERNATIVE 1: Treatment with recycling of manganese oxides

The manganese oxides contained in used batteries could be recycled as a raw material intended for the metallurgical industries for the manufacture of ferro-manganese. In this case, the process applied must make it possible to decontaminate these oxides by eliminating unwanted impurities such as mercury and cadmium.

a - Treatment and recycling of powders from the active mass

At the outlet of the mechanical separator 6, the powders constituting the active mass of the spent cells and batteries passes through a magnetic separator 11 which performs a separation to eliminate the metallic iron dust originating from the abrasion of the envelopes of the cells during the grinding operations and disintegration (in units 3 and 5), and / or the fine particles of ferric oxide from the corrosion of the cells. This fraction of ferrous metals and oxides, approximately 4 to 8% of the total mass, is added to the main fraction of ferrous metals for direct recycling by metallurgical means.

At the outlet of the magnetic separator 11, the powders are mainly composed of manganese oxide (52%), zinc oxide and / or hydroxide (38%), graphite powder (8%) and minor compounds ( oxides and hydroxides of cadmium and mercury: <2%). This mass M of powders, which represents approximately 55 to 60% of the total mass of the treated cells and batteries, is then transported to a reactor-mixer 13 by means of an endless screw 12 (FIG. 2).

In the reactor 13, the mass of powders is dispersed in water to form a dispersion of about 10 to 20% solid. The dispersion is then acidified with concentrated sulfuric acid up to a pH between 1 e 2. On average, 300 to 320 kg of acid will be used for a load of 600 kg of powders. After acidification, 20 kg of potassium permanganate are added to the dispersion. After a reaction time between 30 to 90 minutes, the zinc, cadmium and mercury compounds are selectively extracted from the initial powder mixture by the following dissolution reactions:

Zn (OH) ₂ + H2SO4 = ZnS0 ₄ + 2 H2O

Cd (OH) ₂ + H ₂ S0 ₄ = CdS0 ₄ + 2 H ₂ 0

3 Hg ₂ 0 + 2 KMn0 ₄ + 6 H ₂ S0 ₄ = 6 HgS0 + 2 Mn0 + 2 KOH

+ 5 H ₂ 0

3 Hg + 2 KMn0 ₄ + 3 H ₂ S0 ₄ = 3 HgS0 ₄ + 2 Mn0 ₂ + 2 KOH

+ 2 H ₂ 0

After the dissolution reaction, only the manganese oxides, remaining in the form of Mn0 ₂ , Mn ₂ Û3 and / or MnO (OH), together with the graphite powder constitute the solid insoluble phase of the dispersion.

The use of potassium permanganate as an oxidant in this dissolution stage has two advantages:

The permanganate ion, whose redox potential is + 1.5 volts, is a strong oxidant which even transforms metallic mercury into soluble Hg (II) ions.

- The reaction product of permanganate ions, which is manganese dioxide, does not constitute a new impurity for the reaction mass.

After the selective dissolution of the zinc, cadmium and mercury compounds, the solid residue of the dispersion, consisting mainly of manganese oxides and graphite powder, is separated from the solution by a filter press 14 or by a centrifugal separator . The cake filtration can be washed with a volume of 300 to 600 liters of water per ton of batteries, to eliminate any traces of impurity.

At the outlet of the filter press 14, the solid cake is composed of approximately 50 to 55% of humidity, 40% of manganese oxides and 5 to 10% of graphite powder. By the selective dissolution under the action of sulfuric acid and potassium permanganate, the content of toxic elements such as mercury and cadmium in this filter cake remains below 10 mg / kg (10 ppm). The manganese oxides contained in this cake are clean enough to be recycled, mixed with graphite powders, with or without moisture, by the metallurgical industry for the manufacture of ferromanganese.

b - Treatment and recycling of the zinc sulphate filtrate

At the outlet of the filter press 14, the filtrate is a solution of zinc sulfate with less than 2% toxic impurity of soluble mercury and cadmium.

The soluble mercury compounds in solution are eliminated by ion exchange in a column 17 containing a cationic resin selective for Hg2 ⁺ ions. This resin selectively retains mercuric ions with an efficiency greater than 99.9%. A ratio of 15 to 20 liters of solution for 1 liter of resin is optimal. The flow through the resin bed is preferably adjusted to 2 m / h. Under these conditions, the content of mercury in solution, the outlet of the ion exchanger column 17, is less than 0.05 mg / 1 (50 ppb).

The filtrate, freed from mercury impurities, is then introduced into n reactor-mixer 18. The zinc hydroxide is selectively precipitated there by the addition of caustic soda, in the form of a solution of 30 to 40%, up to pH 7 to 8. Being more soluble, cadmium hydroxide remains in solution with a residual quantity of zinc. The selective precipitation of zinc hydroxide at pH 8 allows recover 98% zinc in solution, or approximately 200 kg of Zn (OH) 2 per tonne of batteries treated. The precipitates of zinc hydroxide are then separated from the solution by a filter press 19.

The residual water leaving the filter press 19, which still contains traces of heavy metals, and the mineral salts from the batteries or the physico-chemical treatment, will be sent for a traditional treatment.

The purity of the zinc hydroxide in the filter cake is greater than 99.9%; the content of impurities is less than 5 mg / kg (5 ppm) for mercury, and 10 mg / k (10 ppm) for cadmium. The zinc hydroxide thus isolated is sufficiently clean to be recycled as a raw material in the production of zinc metal.

The recycling of zinc hydroxide can be carried out in situ by electrolysis. In this case, the zin hydroxide is dosed and transported by an endless screw 20 to a reactor-mixer 21, where the zinc hydroxide is redissolved in a solution of sulfuric acid. The acid concentration and the amount of zinc hydroxide are adjusted so that the content of Zn ²⁺ ions in solution is between 30 to 50 g / 1, and the final pH is between 3.5 and 4.5. The resulting zinc sulphate solution is circulated, in a closed loop, between the reactor-mixer 21 and an electrolysis cell 22. The electrolysis is preferably carried out with cathodes of polished stainless steel and with anodes of graphite or titanium activated at Ru0 ₂ . The cell voltage applied should be between about 3.0 to 3.5 Volts, the cathode current density should preferably be between 200,400 A / m ² .

By cathodic reaction, the Zn ²⁺ ions discharge the cathode and deposit in the form of zinc metal. At the anode the acidity of the solution is regenerated by the consumption of OH- ions giving rise to a release of oxygen. The regenerated acidity is used to dissolve a new charge of the zinc hydroxide provided by the screw 20. The contribution zinc hydroxide is adjusted so that the p of the solution in the reactor 21 does not exceed the value of 4.5.

The metallic zinc recovered by electrolysis has a purity greater than 99.9%. It can therefore be directly sold on the market as a secondary metal. About 130 kg of zinc metal are thus recovered per tonne of spent cells and batteries.

ALTERNATIVE 2: Treatment without recycling of manganese oxides

If the recycling of manganese oxides was not economically favorable, these should be disposed of in a stabilized form for final storage. The process applied could be simplified since the decontamination of these oxides would no longer be necessary. a - Treatment of active mass powders

At the outlet of the mechanical separator 6, the powders constituting the active mass of the spent cells and batteries still contain 3 to 6% of iron dust originating from the abrasion of the envelopes of the cells during the grinding and disintegration operations in the units 3 and 5. In this case, the elimination of this iron dust by the magnetic separator 11 is no longer necessary. The mass M '(Figure 3) is therefore delivered directly from the separator 6 in the worm screw 12.

In the reactor 13, the mass M 'of powders is dispersed in water to form a dispersion of about 10 to 20% solid. The dispersion is then acidified with concentrated sulfuric acid to a pH between 3 and 4. After the acidification, the mixture is stirred for 90 to 120 minutes, at room temperature, to allow the carburization of the mercury on the metallic iron dust according to the reactions:

Hg ²⁺ + Fe -> Hg / Fe + Fe ²⁺ Hg ₂ ²⁺ + Fe -> 2Hg / Fe + Fe ²⁺

The cementation of impurities can be completed by the addition of 0.2 to 0.6 g of zinc powder per liter of solution. In this case, all the metallic impurities more noble than zinc can be eliminated in the form of a solid, in particular:

Hg ²⁺ / Hg2 ²⁺ + Zn -> 2Hg / Zn + Zn ²⁺

Cu ²⁺ + Zn -> Cu / Zn + Zn ²⁺

Ni ²⁺ + Zn -> Ni / Zn + Zn ²⁺

Cd ²⁺ + Zn -> Cd / Zn + Zn ²⁺

After the dissolution and cementation reactions, the manganese oxides, in the form of Mn0 ₂ , Mn ₂ θ3 and / or

MnO (OH), metallic dust of iron or zinc with cemented metals constitute with the graphite powder the insoluble solid phase of the dispersion. These insoluble solids are separated from the solution by the filter press 14, or by a centrifugal separator.

At the outlet of the filter press 14, the solid cake is composed of approximately 50 to 55% of humidity, 40% of manganese oxides, 5 to 10% of graphite powder and 0.1 to 0.2% of dust. iron or zinc with cemented impurities. These manganese oxides are unsuitable for recycling, and must be stabilized for final storage.

The immobilization of the manganese oxides can be carried out according to the process described in the European patent application EP-A-0 369 946. In this process, the filter cake is transported in the wet state by an endless screw towards a special mixer. A binder, composed of cement and specific additives, is added to the mixture in a proportion of 20 to 40%. In this special mixer, the final mixture is transformed into stabilized granules which can be used as a substitute for gravel in the drainage layers of landfills. b - Electrolysis of the zinc sulphate filtrate

On leaving the filter press 14, the filtrate is a colorless and clear solution which contains 45 to 50 g / l of Zn and 5 to 10 g / l of Mn in the form of sulfates. By carburizing, the content of foreign metals such as Cu, Ni, Hg, Cd is generally less than 1 mg / 1.

The filtrate is then sent directly to the electrolysis cell 22 for the recovery of zinc. The electrolysis is preferably carried out with cathodes in polished stainless steel with anodes in graphite, lead or a Pb-Ag alloy. Preferably, the cell voltage applied must be between 3.0 to 3.5 volts, the cathode current density must be between 200 and 400 A / m ² . During the electrolysis, the pH of the solution is maintained between approximately 3.0 and 4.0 by the controlled addition of a 30% NaOH solution.

The reactions at the electrodes are respectively:

Cathode: Zn ²⁺ + 2 e ^~ -> Zn

Anode: Mn ²⁺ + 4 OH ^~ -> Mn0 ₂ + 2 H ₂ 0 + 2 e ^~

or 2 OH- -> 1/2 0 ₂ + H ₂ 0 + 2 e ^~

The electrolysis is continued until a residual concentration of Zn between 0.3 and 0.5 g / 1. After the electrolysis, the mother liquors are sent to the water treatment for neutralization and final precipitation of the residual heavy metals before discharge.

There is thus recovered between 120 to 130 kg of zinc of purity greater than 99%, and 30 to 50 kg of MnO per tonne of batteries treated.

AIR TREATMENT

The air flow A coming from the filter 9, as well as those from the ventilation of the grinder 3, the conveyor belt 4, the disintegrator 5 and the separator 6 contain a certain amount of dust, and powders from the active mass of cells and batteries. These air flows must be treated and decontaminated before being released into the atmosphere.

The overall air flow is sucked in by a fan 2 through a washer 24 at a flow rate of approximately 7,500 m ³ / h. inside the washer 24, the air flow passes through a Venturi tube and creates a vacuum allowing suction of the water from an in-situ tank and spraying it in the form of a spray, in fine droplets. The air flow is thus washed with water spray and freed of all dust or powders. The latter, which have fallen to the bottom of the washer, are periodically removed in the form of sludge to the mixing reactor 13 for the physico-chemical treatment.

To remove volatile mercury or other contaminants, the air flow at the outlet of the washer 24 is successively washed against the current with a solution containing 1 to 5 g / 1 of sulfuric acid and 1 to 5 g / 1 of permanganate of potassium, and with a solution containing 1 5 g / 1 of caustic soda in absorption columns 26 e 27. These washing solutions are periodically purged ^" e sent to the reactor-mixer 13 for the physico-chemical treatment.

The air flow, thus freed from all odors, dust and toxic contaminants, is released into the atmosphere without harm to the environment.

EXAMPLES

Example 1: Physical treatment of cells and batteries

A ton of used cells and batteries from public collections have the following dimensions and chemical composition: Table 1: Distribution of used cells and batteries by size

Table 2: Chemical composition

This batch of cells and batteries is subjected to the physical treatment of the process described above under the following conditions:

Mill 3: knife mill type G-40 St ANDREA; power: 30 kW; flow rate: 1,600 kg / h.

Disintegrator 5: hammer mill type MU-89

TM

EHINGER IMPIANTI; power: 55 kW; load: 40 kg; separator grid at 8 mm opening; automatic discharge door opening program: 2.5 minutes.

Aerodynamic separator 8: SEV- type wind-separator

TM DD 880000 EEHHIINNGGIER IMPIANTI; power: 3 kW; air flow 3,000 Nm ³ / h. TM

Magnetic separator 10: ERIEZ drum separator magnetic force: 5,000 Gauss.

At the outlet of the mechanical separator 6, the following two fractions are obtained:

- a fine fraction (<8 mm) with a total weight of 600 kg, composed of brown-black powders, of homogeneous appearance.

a coarse fraction (> 8 mm) with a total weight of 400 kg, consisting of pieces of metals, paper and plastic. Paper and plastic have a lustrous gray appearance resulting from rubbing with graphite powder.

The average temperature of the fractions is 40 - 60 ° C. This rise in temperature results from one overheating due to friction during grinding and disintegration operations.

At the exit of the aerodynamic 8 and magnetic 10 separators, the separation of the coarse fraction leads to the following inert waste and recyclable metal fractions:

Table 3: Inert waste and directly recycled metals

These results confirm the validity of the process described. By adequate physical treatment, it is possible to separate from the mass of cells and batteries to be treated the 40% of inert waste and directly recyclable metals. The mercury and cadmium content of these separated materials is well below the authorized standard, which makes any further processing unnecessary.

Example 2: Physico-chemical treatment

100 kg of the fine fraction of Example 1 obtained at the outlet of the mechanical separator 6 after the disintegration, are passed through a magnetic separator 11, Figure 1. At the end of this operation, we obtain:

a magnetic fraction with a total weight of 12.8 kg, composed of iron filings and ferric oxide powders.

a non-magnetic fraction with a total weight of 87.2 kg, composed of fine powder, brown-black in color.

The magnetic fraction is added to the fraction of ferrous metals of Example 1 for direct recycling.

The non-magnetic fraction is then dispersed in

600 liters of water, with good stirring, to obtain a dispersion containing about 15% of solids. A charge of

52.5 kg of concentrated H ₂ S0 ₄ is then added to the mixture, in portions of approximately 3 kg every 5 minutes. It is also possible to use an equivalent charge of used acid of 50 to 80%. At the end of the operation, the temperature of the mixture can rise to around 40 ° C, and the pH is stabilized at 1.8. A charge of 3.4 kg of KMn0 is then added to the mixture, in the form of a 10% solution. After 90 minutes of stirring at room temperature, the pH of the mixture is increased to 2.0. The excess of KMn0 is observed by the violet coloration of the solution after decantation.

The insoluble powders of the manganese and graphite oxides are then separated from the mixture by a filter press. The cake is washed with 50 liters of water which are then added to the filtrate. At the outlet of the filter press, the cake is in the form of a wet black mud.

The filtrate has a purple color due to the excess of KMn0 which is destroyed by the addition of H ₂ O ₂ at 30% until a colorless solution is obtained (Filtrate 1).

The resulting solution is then pumped through a column 20 cm in diameter and 150 cm in height containing about 40 liters of ion exchanger resin

Cationic TM of the ALM-125 NISSO type. The pumping rate is adjusted so that the speed of passage of the liquid in the column is between 1.5 to 2 m / h.

After the ion exchange operation (Filtrat l '), the solution is neutralized to pH 8 with a 30% NaOH solution. A white precipitate of zinc hydroxide is formed instantly, and it is separated by a filter press. The cake is then washed with 50 liters of water. The filtrate, added with rinsing water, is eliminated as residual water (Filtrat 2).

The chemical analyzes of the various solutions and filter cakes are reported in Tables 4 and 5.

Table 4: Chemical analysis of the solutions

Table 5: Chemical analysis of filter cakes

These results demonstrate the effectiveness of the physico-chemical treatment of the active mass of used cells and batteries. This treatment makes it possible to separate the two main components, which are manganese oxides and zinc hydroxide, with sufficient purity to be recycled by a traditional metallurgical or electrolytic process. The physico-chemical treatment also makes it possible to remove toxic contaminants such as mercury and cadmium contained in cells and batteries. The final content of Hg and Cd in manganese oxide and zinc hydroxide sludge is much lower than the accepted standard for recycling products.

Claims

1. A process for the bulk treatment of spent cells and batteries comprising a physical separation followed by a physico-chemical treatment, characterized by a physical separation comprising:

(a) at least one grinding and disintegration step which transforms the cells and batteries into a uniform mass; and

(b) mechanical, aerodynamic and magnetic separation steps which separate inert residues and directly recyclable metals from the uniform mass, leaving a toxic active mass of cells and batteries;

followed by a physico-chemical treatment of this toxic active mass in order to provide at least one non-toxic recyclable product.

2. The method of claim 1 where step (a) is characterized by:

the use of a knife mill to reduce cells and batteries of different sizes and shapes into uniform particles of dimensions between 0.5 and 1.5 cm; followed by

the use of a hammer mill to disintegrate the active mass of cells and batteries into fine powders, while keeping the metal, paper and plastic structures to a dimension between 0.5 and 1.5 cm.

3. The method of claim 1 or 2, wherein step (b) is characterized by the use of mechanical, aerodynamic and magnetic separators for the respective separations of inert residues and metals from the active mass of cells and batteries, inert residues of paper and / or plastic and metals, and finally ferrous and non-ferrous metals, the separate proportions being 55 - 60% by weight of toxic active mass to be treated, 5 - 10% weight of inert residues to be removed and 30 - 40% weight of metals to be recycled directly.

4. The process of claim 1, 2 or 3, where the physico-chemical treatment comprises at least the following steps:

(c) selective dissolution-oxidation making it possible to separate and purify the manganese oxides in the form of recyclable filter-pressed sludge;

(d) decontamination of mercury and / or cadmium ions;

(e) selective precipitation making it possible to separate and purify the zinc compounds in the form of recyclable filter-pressed hydroxyd mud;

(f) selective dissolution combined with cementation of impurities on iron or zinc dust to obtain a directly electrolyzable solution of zinc sulphate; and

(g) stabilization of the manganese oxides, with the impurities, by immobilization with a binder such as cement for final storage.

5. The method of claim 4, comprising a step

(c) characterized by a selective dissolution in a sulfuric medium, at a pH between 1 and 4, in the presence of a strong oxidant, compounds of at least one of zinc, nickel, copper, cadmium, mercury, as well as their inorganic salts, so as to separate the manganese oxides and the graphite in the form of an insoluble powder.

6. The method of claim 5, wherein step (c) is followed by a step of stabilizing the mud of manganese oxides and graphite with cement, transforming them into inert granular residues usable for construction .

7. The method of claim 4, comprising a step (d) characterized by the use of KMn04 as an oxidizing agent, making it possible in particular to dissolve the mercury metal and its insoluble compounds by oxidizing them to mercury (II) salts.

8. The process of any of claims 4 to

7, comprising a step (d) characterized by the use of a selective ion exchanger resin as a means of removing mercury from the solution for dissolving the active mass of cells and batteries.

9. The process of any of claims 4 to

8, comprising a step (e) characterized by a selective precipitation of zinc hydroxide from the solution for dissolving the active mass of cells and batteries, at a pH between 7 and 9.

10. The process of any of claims 4 to

9, comprising a step (e) or (f) followed by an electrolysis of a sulfuric dissolution of the zinc hydroxide for its recycling in the form of a metallic deposit of purity of 99.9% or more.

11. Use of the process of any one of claims 1 to 10 to recover at least one of manganese oxide, zinc, and ferrous and non-ferrous metals from used batteries.

12. The method of claim 4, comprising a selective dissolution-oxidation step (c), followed by a contamination step (d) and a selective precipitation step (c).

13. The method of claim 4, comprising a selective dissolution-oxidation step (c), followed by a selective dissolution step (f) and a stabilization step (g).