TECHNICAL FIELD OF THE INVENTION

The invention will find application in the field of waste management and in particular in recovery of process waste obtained from lead-acid recycling.

BACKGROUND OF THE ART

The closest known solution is described in published patent application WO2018/145172 Al. The known method includes acceptance and pretreatment of waste, while initially their size is reduced, and then ferrous metals and lead are separated and extracted through separate outlets for further use. The rest of the hazardous waste is neutralized with an alkaline solution, after which chemical treatment is carried out for decontamination with subsequent drying. Then, the treated waste is sorted and acrylonitrile butadiene styrene and polyvinyl chloride are separated and landfilled. Polypropylene is also separated and collected for further recycling. Polyethylene separators with silica filler are also separated and collected in a hopper for further processing, as well as residues of other materials collected for landfilling. The separated polyethylene separators with silica filler are fed to the next treatment stage for processing through gasification, where a gaseous phase of evaporated polyethylene and mineral oil and a solid phase of amorphous silica are produced. The gaseous phase produced in the process is fed to the next stage, representing a combustion process in a thermal oxidizer at a temperature not lower than 900°C. After the combustion process, the hot gases from the thermal oxidizer are fed for heat recovery in an energy module. The amorphous silica extracted from the gasification is subjected to cooling, grinding, and packaging as a commercial product.

The known method is applied in a plant of several units corresponding to the sequence of the operations according to the method, while they include a magnetic drum conveyor with one outlet for ferrous metals collected in a container for further recycling and with a second outlet to a separator for non-ferrous metals; (lead) connected to a shredder for waste, followed by a chemical treatment machine connected through a screw conveyor to a corresponding drying device, which is connected through a pneumatic transport system to a hopper with a vibrating dosing feeder that feeding a waste sorting system from the sorting unit. The waste sorting system sorts in two stages, while at the first stage the waste is separated into two streams: hard plastics (polypropylene PP, acrylic butadiene styrene ABS, polyvinyl chloride PVC) and polyethylene separators with silica filler and waste from other materials. At the second sorting stage, the two waste streams generated by the first stage are subjected separately to additional sorting: from hard plastics (polypropylene PP, acrylic butadiene styrene ABS, polyvinyl chloride PVC), polypropylene is separated, which is collected for further recycling, as well as other waste, which is collected for landfilling; from the stream of polyethylene separators and other materials, polyethylene separators are separated, which are collected for further processing, as well as waste from other materials, which are collected for landfilling.

The polyethylene separators with silica filler separated from thei sorting processes are fed to a gasifier equipped with an exhaust fan which takes ' away the evaporated polyethylene gases to a thermal oxidizer, where the gases from the evaporated polyethylene are burn. The thermal oxidizer is connected through a gas duct to a heat recovery boiler, where the heat energy of the gases from the thermal oxidizer is recovered. From the gasifier, a solid heated phase is extracted, which is amorphous silica that is cooled, ground, and packed for further use as a commercial product. Thus, the produced amorphous silica should be of “Silica Fume” type (or “Pyrogenic silica”), i.e. thermal process product (CAS number 112945-52-5).

The disadvantages of the known solution are that the separation of silica is carried out through processes with relatively high thermal losses - high-temperature gasification of polyethylene separators, the gaseous phase from which is burned in a thermal oxidizer at a temperature above 900°C. Moreover, also, the acrylonitrile butadiene styrene (ABS) quantity is not recovered and is landfilled, which requires specific measures and facilities. The use of high-temperature gasifier and thermal oxidizer leads to high operating costs and requires specific maintenance, which significantly increases the cost of waste treatment.

SUMMARY OF THE INVENTION

The problem facing the present invention is the creation of a method for recovery of hazardous waste generated from the battery recycling processes, as well as an installation for its implementation, with which hazardous waste is processed into products for further use or recycling, while the residue for landfilling is less than 5% of the total waste, where high-temperature treatment of the waste is avoided.

The problem is solved with a method for recovery of waste from processes for recycling of lead-acid batteries, which includes a waste pretreatment stage, where ferrous and non-ferrous metals (lead, etc.) are extracted from the stream. According to the invention, the treatment of the waste passes successively through three stages: stage A of acceptance of the contaminated waste, which starts the method followed by stage B of pretreatment of the waste, and stage C of the main treatment. At stage A of acceptance of the contaminated waste, the weight and the moisture of the contaminated waste are measured and then the contaminated waste is fed to pretreatment stage B, while after the extraction of the ferrous and non-ferrous metals the stream of contaminated waste is divided by screening into two fractions - contaminated waste smaller than 30mm and contaminated waste larger than 30mm. The contaminated waste larger than 30 mm is treated by cutting and shredding, while the shredded waste already smaller than 30 mm and the contaminated waste smaller than 30 mm are transported pneumatically to a separating cyclone, where the contaminated waste is separated from the transporting air, while the air is filtered and discharged into the atmosphere, and the separated contaminated waste is treated by a four-stage washing, in which the lead cake and the washing solutions are released. The lead cake is collected and taken away for further recycling, and the four-stage washed waste is fed to a friction washer, where the final washing of the waste is carried out, and then the waste is dewatered. Then, the dewatered waste is divided by screening, where a fraction larger than 6 mm and a fraction smaller than 6 mm are separated, the latter of which is process waste that is filled into bags for landfilling. The larger than 6 mm dewatered waste fraction is sorted in two ballistic sorting machines connected in series, and three sorted fractions are released, of which: the first sorted fraction consists of polyethylene (PE) flakes with amorphous silica filler, absorbent glass mat (AGM), labels and other light or 2D fractions; the second sorted fraction consists of: hard plastic chips (PP - polypropylene, ABS - acrylonitrile butadiene styrene and ebonite), polyvinylchloride separators and other heavy or 3D fractions; the third sorted fraction is fine process waste, which is taken away for landfilled. Then the first and the second sorted fractions are separately sorted optically and three streams from washed, dewatered, and sorted materials are generated; the first is chips of polypropylene (PP), and chips of acrylonitrile butadiene styrene (ABS), which are collected separately and taken away for further recycling. The second stream is from polyethylene (PE) flakes with amorphous silica filler, which is fed to the main treatment stage C, and the third stream is from everything else, so-called ''process waste", which is collected and taken away for landfilled. The polyethylene (PE) flakes with amorphous silica filler are treated chemically by at least one extraction machine and in this chemical treatment silicate aqueous solution and sorted polyethylene flakes are obtained. The silicate aqueous solution produced by the chemical treatment is subjected to a two-stage filtration, homogenization, and precipitation for production of suspension of amorphous silica, which is fed for washing. Then, the washed amorphous silica suspension is collected and fed to a chamber filter press, where final washing and dewatering of the amorphous silica is carried put, and the resulting amorphous silica cake is fed for drying and packaging into bags. The polyethylene flakes remained in the extraction machine are treated finally by a friction washer, after which the washing solution is filtered and drained, and the washed polyethylene flakes are fed for dewatering and filling into bags.

The four-stage washing of the separated contaminated waste is carried out in a washing machine and includes the following processes in the stages combined in a washing cycle: at the first stage, simultaneous loading of a waste, pre-wetting of the waste with an alkaline solution, and filling of the washing machine with the alkaline solution, which is an aqueous solution of KOH with a temperature of 25°C to 45°C, while during the loading of the waste, the above alkaline solution is injected in the opening of the washing machine. Alkaline washing is carried out, while the waste is stirring and the solution recirculates, maintaining the hydrogen index of the solution in the machine pH = 10 12 and duration of the process up to 30> minutes, while adding an aqueous solution of H ₂ O ₂ and washing while the waste is stirring and the solution recirculates and duration of the process up to 10 minutes, followed by double sequential filtration of the solution in the washing machine and its drainage into a tank and discharging the cake from the filters, which cake is collected in a container for further recycling. At the second stage, washing is carried out with deionized water, while the washing machine is filled with deionized water, and washing, stirring, and recirculation is carried out at a temperature of 25°C to 45°C and the duration of the process is up to 10 minutes, followed by a third stage - acid washing - loading of an aqueous solution of HNO ₃ at a temperature of 25°C to 45°C and washing with stirring of the waste and recirculation of the solution, while maintaining the hydrogen index of the solution in the washing machine pH = 1,5 3,5 and duration of the process up to 30 minutes. Then, an aqueous solution of H ₂ O ₂ is added and the waste is stirred and the solution recirculates and the process duration is up to 10 minutes, followed by draining of the solution into a tank. At the fourth stage, the washing cycle ends with washing with deionized water, while the washing machine is filled with deionized water with a temperature of 25°C to 45°C and the washing is carried out while the waste is stirred and the solution recirculates and the process duration is up to 20 minutes, followed by draining of the solution into a tank and unloading of the washed waste and feeding it to the friction washer.

The chemical treatment for the extraction of amorphous silica in at least one extraction machine is carried out by first loading the extraction machine with pre-washed and sorted polyethylene (PE) flakes with amorphous silica filler, while simultaneously the sorted polyethylene flakes are treated by injecting an alkaline solution into the loading opening of the extraction machine and the extraction machine is simultaneously filled with the same alkaline solution. The alkaline solution is an aqueous solution of KOH with a temperature of 75°C to 95°C, and the process of extraction of amorphous silica by the alkaline solution is carried out under the following conditions: atmospheric pressure; stirring of the polyethylene (PE) flakes with amorphous silica filler; of recirculation of the alkaline solution; maintaining the temperature of the solution in the extraction machine t = 75°C95°C; maintaining the hydrogen index of the solution in the extraction machine pH = 12÷ 13 and duration of the process Up to 100 minutes. The extracted amorphous silica is in the form of silicate aqueous solution, which is filtered mechanically at least at two stages, while the retentate from the filters is drained into a tank and the permeate is drained from the extraction machine for two-stage filtration, homogenization, and precipitation in at least one reactor-precipitator. After the draining of the silicate aqueous solution from the extraction machine, the remaining polyethylene flakes in it are treated by at least one washing and this washing is carried out with deionized water with a temperature of 75°C to 95°C, and after the washing, the washing solution is filtered and drained into the same reactor-precipitator and after that, the remaining polyethylene flakes are washed twice with deionized water with a temperature of 25°C to 45°C and then they are taken out from the extraction machine.

The two-stage filtration, homogenization, and precipitation of the silicate aqueous solution are carried out in at least one reactor-precipitator, while the two-stage filtering is sequential and carried out through recirculation in the reactor-precipitator; retentate is discharged from the filters and is taken away into a tank, while the permeate is returned to the reactor-precipitator. The homogenization and filtration of the silicate aqueous solution are carried out at the following conditions: atmospheric pressure; maintaining the temperature of the silicate aqueous solution from 75°C to 95°C and maintaining the hydrogen index of the solution in the reactor-precipitator pH = 12÷ 13 and duration of the process up to 30 minutes, after which the silicate aqueous solution is cooling down to 60°C and precipitation of amorphous silica occurs. The precipitation is carried out with stirring without recirculation of the silicate aqueous solution at the following conditions: dosing an aqueous solution of HNO ₃ until obtaining; hydrogen index of the solution pH = 1,5 ÷ 3,0 with a duration of the process up to 30 minutes, while the precipitation results in a suspension of amorphous silica, which is fed to a washing reactor. Then, the reactor-precipitator is washed with deionized water with a temperature of 60°C to 65°C, and the washing solution is fed to the above washing reactor.

The washing of the precipitated amorphous silica suspension is carried out in at least one washing reactor with deionized water with a temperature of 60°C to 65°C and filtered until the value of the electrical conductivity of the suspension falls below than 1000 pS and after reaching the setpoint for the electrical conductivity of the aqueous suspension of amorphous silica the permeate from the filters is fed to a tank for further treatment, and the retentate is collected in a shared silicate tank.

The problem is also solved with an installation for implementing the method for recovery of waste from processes for recycling of lead-acid batteries, which includes hoppers, conveyors, shredders, sorting, and washing equipment, including a receiving hopper and an inlet conveyor belt. According to the invention, a system for measurement of the moisture is located before the receiving hopper, followed by a system for measurement of the weight of the contaminated waste and a receiving conveyor belt connected to the receiving hopper connected to the inlet conveyor belt. An over-belt electromagnetic separator with an outlet to a container for ferrous materials is mounted on it. The inlet conveyor belt is connected to a second conveyor belt, and a tunnel metal detector is mounted on it. Downstream the second conveyor belt there is a screen with two outlets, of which the first outlet is for waste smaller than 30 mm and is connected by a pneumatic transport to a separating cyclone, and downstream to a hopper located under the separating cyclone. The second outlet is for waste larger than 30 mm connected to a universal shredder equipped at outlet with a blower for pneumatic transport connected to the separating cyclone. The separating cyclone is equipped with an air filter, and under the hopper, after the separating cyclone, there is a dosing feeder with an outlet to a washing machine with an outlet for a container for lead cake, an_outlet to three tanks for washing solutions, and an outlet to a chain conveyor followed by a buffer conveyor. The buffer conveyor is connected to a friction washer with an outlet to a mechanical dryer connected by a pneumatic transport to an intermediate hopper with a second dosing feeder with an outlet to a separating screen. The separating screen has two outlets: the first outlet for washed waste larger than 6 mm to two - first and second — ballistic sorting machines connected in series and a second outlet for washed waste smaller than 6 mm connected to a bag filling system. The first ballistic sorting machine has three outlets, which are: one outlet connected to the second ballistic sorting machine, another outlet to a discharge hopper, and a third outlet, under the screen of the machine, for process waste connected to a second bag filling system. The second ballistic sorting machine also has three outlets - the first outlet connected to a second intermediate hopper; the second outlet connected to the discharge hopper and the third outlet for fine process waste connected to the second bag filling system. The discharge hopper is connected through a third dosing feeder to an optical sorting machine, which also has three outlets: one to a third bag filling system - for polypropylene; another outlet connected to a fourth bag filling system - for acrylonitrile butadiene styrene and a third outlet connected to a fifth bag filling system - for process waste. The second intermediate hopper is connected through a fourth dosing feeder to a second optical sorting machine with two outlets - outlet to the main hopper - for polyethylene (PE) flakes with silica filler and outlet to a sixth bag filling system - for process waste. The main hopper is connected through a fifth dosing feeder to a blow-through rotary valve of a system for pneumatic transport - from the “C” main treatment stage, carried out by a compressor. The pneumatic transport system is tubular and is connected to at least one extraction machine with two main outlets, one of which is connected to the respective reactor-precipitator, downstream of which at least one washing reactor is located. The washing reactor is downstream connected to a shared silicate tank, a chamber filter press and a silicate cake hopper downstream connected to a dryer with an outlet to a system for packaging of amorphous silica. The second outlet of that at least one extraction machine is located on the bottom of it, and below it a shared chain conveyor is located downstream connected to a second, buffer conveyor and a second friction washer downstream located. Downstream the second friction washer, there is a second mechanical dryer connected to the seventh bag filling system — for collecting of polyethylene flakes. The advantages of the invention are in the designed simplified technology scheme using energy-efficient technology processes, where, in addition to the separation of recyclable waste, including lead and ferrous metals, polypropylene (PP) and amorphous silica - which is a commercial product ready for incorporation in other industrial production, acrylonitrile butadiene styrene (ABS) and^ polyethylene (PE) are recovered, as well as the lead cake from the processes of waste washing is collected for further recycling. Shorter washing processes are also achieved, as well as lower energy costs due to low-temperature processes. Moreover, ah opportunity has been created for the full automation of all technological processes. The technology has a higher priority order within the management hierarchy of waste within the meaning of Directive 2008/98/EC, Art. 4(§).

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 - block diagram of the installation implementing the method, according to the invention.

Fig. 2 - flow diagram of the installation implementing the method, according to the invention.

EXAMPLES OF EMBODIMENTS OF THE INVENTION

The method for recovery and utilization of waste from processes for recycling of lead- acid batteries, which waste is contaminated with metal compounds and dried up electrolyte and which waste consists of separators between electrodes, plastics from battery boxes, metals, and other materials, is based on processes for mechanical and physical-chemical treatment of the waste.

According to the invention, the following treatment stages are planned: stage A of acceptance of the contaminated waste, the method starts, followed by stage B of pretreatment of the waste, and stage C of the main treatment.

At each stage, operations are executed according to the method as follows:

According to the invention, at stage A of acceptance of the contaminated waste, the weight and the moisture of the contaminated waste are measured. Then the contaminated waste is fed to the pretreatment stage B, where the ferrous and nonferrous metals (lead) are separated from the contaminated waste. The remaining contaminated waste is divided by screening into two fractions - contaminated waste smaller than 30 mm and contaminated waste larger than 30 mm. The contaminated waste larger than 30 mm is treated by cutting and shredding, while the cut and shredded waste which is already smaller than 30 mm and the screened contaminated waste smaller than 30 mm are transported pneumatically to a separating cyclone, preferably paired, where the contaminated waste is separated from the transporting air, while the air is filtered and discharged into the atmosphere. The separated contaminated waste is treated by a four-stage washing, where the lead cake and the washing solutions are released, while the lead cake is taken away for further recycling and the washing solutions are collected separately for further treatment.

The four-stage washing is carried out cyclically with batches in a washing machine and includes the following processes combined in the first stage: simultaneous loading of batches of contaminated waste, pre-wetting of the contaminated! waste with an alkaline solution, and filling of the washing machine with an alkaline solution, which is an aqueous solution of KOH with a temperature of 25°C to 45°C. During the loading of the waste, the above alkaline solution is injected in the opening of the washing machine. Alkaline washing is carried out with stirring of the contaminated waste, recirculation of the solution, and maintaining the hydrogen index of the solution in the washing machine pH = 10 ÷ 12. The duration of the process is from 4 to 30 minutes. An aqueous solution of H ₂ O ₂ (hydrogen peroxide) is added and the washing with stirring and recirculation continues. Duration of the process is from 4 to 10 minutes. Then the solution is filtered twice in succession and drained into a tank, while the cake is discharged from the filters and collected in a container for further recycling.

At the second stage of the four-stage washing, washing is carried out with deionized water, while the washing machine is filled with deionized water, and washing, stirring, and recirculation is carried out at a temperature of 25°C to 45°C, and the duration of the process is from 3 to 10 minutes after which the washing solution is filtered twice in succession and drained into a tank, while the cake discharged from the filters is collected in a container.

A third washing stage follows, which is acidic washing carried out with an aqueous solution of HNO ₃ (nitric acid) and stirring and recirculation of the solution at a temperature of 25°C to 45°C while maintaining the hydrogen index of the solution in the washing machine pH=1,5÷ 3,5. The duration of the process is from 4 to 30 minutes. Then, an aqueous solution of H ₂ O ₂ (hydrogen peroxide) is added and the waste is stirred and the solution recirculates and the process duration is from 4 to 10 minutes, followed by draining of the solution into a tank. At the fourth stage, the washing cycle ends with washing with deionized water while the waste is stirred and the solution recirculates at a temperature of 25°C to 45°C and the process duration is from 10 to 20 minutes, followed by draining of the solution into a tank and unloading of the washed waste. For the unloading of the washed waste, it is appropriate to use a chain conveyor mounted under the washing machine feeding the washed waste to a buffer conveyor providing an uninterrupted process.

The washed waste is fed to a friction washer, where its final washing is carried out, after which the washed waste is dewatered.

Then, the dewatered waste is divided by screening, where a fraction larger than 6 mm and a fraction smaller than 6 mm are separated, the latter of which is filled into bags, and dewatered waste larger than 6 mm is sorted in two ballistic sorting machines connected in series, while three sorted fractions are obtained at the outlet of the process, of which the first sorted fraction is polyethylene (PE) flakes with amorphous silica filler, absorbent glass mat (AGM), labels and other light or 2D fractions; the second sorted fraction consists of hard plastic chips (PP - polypropylene, ABS - acrylonitrile butadiene styrene and ebonite), polyvinylchloride (PVC) separators and other heavy or 3D fractions, while the third sorted fraction is fine process waste, which is taken away for landfilling.

Then the first and the second sorted fractions are separately sorted optically and three streams from washed, dewatered, and sorted materials are obtained of which one is chips of polypropylene (PP) and chips of acrylonitrile butadiene styrene (ABS), which are collected separately and taken away for further recycling. The second stream is from polyethylene (PE) flakes with amorphous silica filler which is fed to the main treatment stage C, where the amorphous silica is extracted from the optically sorted flakes of polyethylene (PE) with amorphous silica filler. The third stream is from everything else and is called ‘process waste’, which is collected and taken away for landfilling.

The amorphous silica is extracted by chemical treatment in at least one extraction machine, which is loaded cyclically with batches of optically sorted polyethylene flakes with amorphous silica filler and an alkaline solution. While the extraction machine is loading with the optically sorted polyethylene flakes the same alkaline solution is injected into the loading opening of the machine. Alkaline solution is an aqueous solution of KOH (potassium hydroxide) with a temperature of 75°C to 95°C.

The example shows one extraction machine, but according to the present method and depending on the volume of the treated contaminated waste, more extraction machines can be designed, observing the sequence and the cyclicity, as indicated here.

The chemical treatment for the extraction of amorphous silica is carried out in at least one loaded extraction machine under the following conditions: atmospheric pressure; stirring of the polyethylene (PE) flakes with amorphous silica filler; of recirculation of the alkaline solution; maintaining the temperature of the solution in the extraction machine t=75°C9 5°C; maintaining the hydrogen index of the solution in the extraction machine pH=12-KL3 and duration of the process is from 60 to 100 minutes. The extraction produces two phases: liquid, in the form of silicate aqueous solution containing amorphous silica, and solid - in the form of polyethylene flakes.

The silicate aqueous solution produced in the extraction machine is subjected to two- stage filtration, after which it is fed for further treatment to at least one reactorprecipitator.

Then the polyethylene flakes are washed with deionized water at a temperature from 75°C to 95°C which, after the end of the washing process is also filtered twice and supplied to the above reactor-precipitator as the silicate aqueous solution. The cake separated from the filters as mechanical contamination is taken away for landfilling.

Then the polyethylene flakes are washed twice with deionized water at a temperature from 25°C to 45°C which, after the end of each washing process is drained into a tank. The polyethylene flakes are unloaded from the extraction machine by a chain conveyor mounted below the extraction machine, which transfers them to a buffer conveyor. The buffer conveyor feeding the polyethylene flakes for final washing by a friction washer, which transfers them for dewatering to a mechanical dryer (usually a centrifuge). The dewatered polyethylene flakes are collected in bags and taken away for further recycling.

The silicate aqueous solution produced after the chemical treatment for the extraction of the amorphous silica is subjected to two-stage sequential filtration and homogenization in the reactor-precipitator, by recirculating the silicate aqueous solution in the reactor-precipitator, while maintaining the temperature of the silicate solution from 75°C to 95°C and maintaining the hydrogen index of the solution pH = 12-^13. The duration of the process is from 5 to 30 minutes. Accordingly, the retentate from the filters is drained into a tank, and the permeate from the filters is returned to the reactorprecipitator. Then the silicate aqueous solution (the permeate) is cooled down to 60°C, the recirculation is switched off and the stirrer is switched on. Then the process of precipitation of the amorphous silica starts by dosing an aqueous solution of HNO ₃ (nitric acid) until obtaining the hydrogen index of the solution pH=l, 5÷ 3,0 with a duration of the process is from 15 to 30 minutes. As a result of the process of precipitation of amorphous silica, two new phases are obtained from the silicate aqueous solution: liquid, in the form of aqueous nitrate solution, and solid - in the form of wet precipitated amorphous silica. The two phases are combined in the form of a suspension of amorphous silica. Then the resulting suspension of amorphous silica is transferred to a washing reactor, after which the reactor-precipitator is washed with deionized water and the washing solution is fed to the above washing reactor.

The washing of the precipitated amorphous silica suspension is carried out with deionized water with a temperature of 60°C to 65°C and filtered until the value of the electrical conductivity of the suspension falls below than 1000 pS; and after reaching the setpoint value for the electrical conductivity of the aqueous suspension of amorphous silica the permeate from the filters is fed to a tank for further treatment, and the retentate - the washed amorphous silica suspension - is collected in a shared silicate tank, from where a pump feeding it to a chamber filter press for final washing and dewatering of the amorphous silica. The washing solutions and the moisture extracted from the chamber filter press are collected in a tank, and the dewatered amorphous silica cake is collected in a hopper equipped with a dosing feeder that feeding the amorphous silica cake to a dryer. In the dryer, the moisture of the cake is evaporated and at the outlet of the dryer, the cake is in the form of a dry powder of amorphous silica, which is fed to a packaging system for amorphous silica, from where it is transferred to storage.

After the execution of the method according to the invention, the following materials are obtained:

1. Main product: amorphous silica.

2. By-products for further recycling:

- Polypropylene (PP)

- Acrylonitrile butadiene styrene (ABS);

- Polyethylene (PE).

- Ferrous and non-ferrous metals

3. Dewatered cake from metal compounds, mainly lead, for further recycling. All solutions discharged from processes are fed to an industrial wastewater treatment plant, which is not subject to the present invention.

The quantity of the process waste depends from the morphological composition of the contaminated waste and usually does not exceed 5%÷ 7% of the total quantity of contaminated waste delivered for recovery.

For the execution of the method for recovery of waste from processes for recycling of lead-acid batteries, an installation is created that includes hoppers, conveyors, shredders, and sorting and washing equipment arranged and connected according to the invention.

The installation for implementing the method includes three modules corresponding to the three stages of the method according to the invention, namely: module A for the waste acceptance stage; module B for the waste pretreatment stage, and module C for the main treatment stage.

The installation for implementing the method includes in Module A a system for measuring moisture 1, followed by a system for measuring the weight of the contaminated waste 2 and a receiving conveyor belt 3. In this module, acceptance, measurement of the weight, and the humidity of the contaminated waste are performed, and transfer of the received contaminated waste to the receiving hopper 31 of Module B, whose facilities provide pretreatment of the waste, is carried out.

The receiving hopper 31 is equipped with a moving floor and a feed drum, through which the waste is dosed to an inlet conveyor belt 4 on which an over-belt electromagnetic separator 41 with an outlet to a container for ferrous materials 42 is mounted. The inlet conveyor belt 4 is connected to a second conveyor belt 5, on which a tunnel metal detector 51 is mounted for separating non-ferrous metals, mainly lead from battery grids, for which a container for non-ferrous metals 52 is provided. Downstream the second conveyor belt 5, there is a screen 6 with two outlets, of which the first outlet is for waste smaller than 30 mm, which outlet is connected by a pneumatic transport 61 to a separating cyclone 72. It is preferable that the separating cyclone 72 is paired, as in the present example. The waste outlet of the separating cyclone 72 is connected to hopper 8 located below it. The second outlet of screen 6 is for waste larger than 30 mm and is connected to a universal shredder 7 equipped with a pneumatic transport blower 71 that feeding the contaminated waste to the separating cyclone 72. The separating cyclone 72 separates the waste from the transporting air and transfers it to hopper 8. Accordingly, a filter 73 is mounted on the paired separating cyclone 72 and cleans the transporting air before it is discharged into the atmosphere.

Hopper 8, where the waste from the first outlet of screen 6 and the waste from universal shredder 7 is collected, is equipped with a dosing feeder 81 located below hopper 8. The dosing feeder 81 has an outlet to a washing machine 9, where the waste is washed. Washing machine 9 is designed with an outlet to a lead cake container 91, an outlet to three tanks for washing solutions 92, 93, 94, and an outlet to a chain conveyor 10 transporting the washed waste from the washing machine 9 to a buffer conveyor 11 connected to a friction washer 12.

The presence of. a buffer conveyor 11 allows to fix in time the duration of the cyclic process in the washing machine 9 with the continuous process of the downstream equipment.

The friction washer 12 has an outlet to a mechanical dryer (centrifuge) 13, where the washed waste is dewatered. The mechanical dryer 13 is connected through a pneumatic transport connection consisting of a blower 131, followed by a second separating cyclone 132 equipped with a filter 133 for cleaning the transporting air before discharging it into the atmosphere. The second separating cyclone 132 has an outlet to an intermediate hopper 14 with a second dosing feeder 141 with an outlet to the separating screen 15. The separating screen 15 has two outlets: the first outlet for washed waste larger than 6 mm to two - first 16 and second 17 - ballistic sorting machines connected in series and a second outlet for washed waste smaller than 6 mm (process waste) connected to a bag filling system 151.

The first ballistic sorting machine 16 has three outlets, which are: one outlet connected to the second ballistic sorting machine 17 - for polyethylene (PE) flakes with amorphous silica filler, absorbent glass mat (AGM), labels, and other light or 2D fractions; another outlet to discharge hopper 19 - for hard plastic chips (PP - polypropylene, ABS - acrylonitrile butadiene styrene and ebonite), polyvinylchloride separates and other heavy or 3D fractions and a third outlet below the screen - for sorted fine waste (process waste), if any. This third outlet for fine waste is connected to a second bag filling system 18.

The second ballistic sorting machine 17 also has three outlets - the first outlet connected to a second intermediate hopper 21 - for collecting polyethylene (PE) flakes with amorphous silica filler, absorbent glass mat (AGM), labels, and other light or 2D fractions; the second outlet connected to the discharge hopper 19 - for hard plastic chips (PP, ABS, and ebonite), PVC separators and other heavy or 3D fractions and a third outlet for fine process waste connected to the second bag filling system 18.

The discharge hopper 19, where the hard plastic chips (PP - polypropylene, ABS - Acrylonitrile butadiene styrene and ebonite), PVC separators and other heavy or 3D fractions from the ballistic sorting machines 16 and 17 are collected, is connected through a third dosing feeder 191 to an optical sorting machine 20, which has three outlets, one of which is to a third bag filling system 201 - for collecting polypropylene (PP); another outlet to a fourth bag filling system 202 — for collecting acrylonitrile butadiene styrene (ABS) and the third outlet to a fifth bag filling system 203 - for collecting the rest, as process waste for landfilling.

After passing certification, the polypropylene (PP) and acrylonitrile butadiene styrene (ABS) chips collected separately in bags are clean enough for recycling in other technological processes.

The waste from the first outlets of the both ballistic sorting machines 16 and 17 is collected in the second intermediate hopper 21, namely sorted flakes (PE) polyethylene with amorphous silica filler, absorbent glass mat (AGM), labels, and other light or 2D fractions. The second intermediate hopper 21 is connected through a fourth dosing feeder 211 to a second optical sorting machine 22, which has two outlets: one outlet to the main hopper 23 - for collecting sorted polyethylene (PE) flakes with amorphous silica filler and another outlet to the‘ sixth bag filling system 221- for collecting the remaining washed and dewatered process waste.

The main hopper 23 is connected through a fifth dosing feeder 321 to a blow-through rotary valve 242 of a tubular pneumatic transport system 24, with compressor 241 from the “C” module of the installation, equipped with facilities for the main treatment stage “C”. The tubular pneumatic transport system 24 is connected to at least one extraction machine 25, which is loaded by the compressor 241 with batches of sorted polyethylene (PE) flakes with amorphous silica filler.

The example shows one extraction, machine 25, whose capacity depends on the extraction cycle duration corresponding to the capacity of the washing machine 9. More than one extraction machine 25 may be provided depending on the quantity of the treated waste and the number of washing machines.

According to the method of the invention, a chemical treatment is carried out in the extraction machine 25 for extraction of the amorphous silica, as a result of its two phases are obtained: liquid, in the form of silicate aqueous solution containing amorphous silica and solid — in the form of polyethylene (PE) flakes. For discharging of the two phases, two different outlets' are provided in the extraction machine 25: first outlet connected to at least one reactor-precipitator 31 and provided for drainage of the silicate aqueous solution and the water from the first washing of the polyethylene flakes. The second outlet is connected to a chain conveyor 26 and is provided for unloading the washed polyethylene (PE) flakes. The extraction machine 25 also has a third outlet connected to a discharge tank 271 - for draining and collecting the solution from the double washing of the polyethylene flakes.

Through the chain conveyor 26, the extraction machine 25 is connected to a second buffer conveyor 27 transporting the washed polyethylene (PE) flakes to the second friction washer 28 connected to a second mechanical dryer 29 (typically - centrifuge) connected through a pneumatic transport system 291 to the seventh bag filling system 30 collecting the washed and dewatered polyethylene (PE) flakes.

After passing certification, the polyethylene (PE) collected in bags is clean enough for recycling in other technological processes.

According to the method of the invention, the silicate aqueous solution discharged from the extraction machine 25 is treated in the reactor-precipitator 31 resulting in two new phases form the liquid phase of the silicate aqueous solution: liquid, in the form of aqueous nitrate solution and solid - in the form of wet precipitated amorphous silica, which two phases are combined in the form of a suspension of amorphous silica. The reactor-precipitator 31 has two outlets: one connected to a washing reactor 32 - for draining the suspension of amorphous silica; another outlet connected to a collection tank 331 for collecting and discharging the mechanical contaminants from the process of filtering the silicate aqueous solution to a waste water treatment plant which is not the subject of the present invention.

According to the method of the invention, the suspension of amorphous silica discharged from the reactor-precipitator 31 is treated in the Washing reactor 32. To carry out the processes of the method, the washing reactor 32 includes a recirculation line having filters connected in series and two outlets: one connected to a shared silicate tank 33 - for draining and collecting the washed suspension of amorphous silica; another outlet connected to the collection tank 331 for collecting and draining the solutions from the processes of washing the suspension to a waste water treatment plant which is not the subject of the present invention.

The shared silicate tank 33, where the amorphous silica suspension washed in washing reactor 32 is collected, is connected to a chamber filter press 34 for final washing and dewatering of the amorphous silica. According to the method of the invention, for carrying out the processes in the chamber filter press 34, the chamber filter press 34 has two outlets: one connected to the collection tank 331 - for collecting and draining the washing solutions and the separated moisture to the waste water treatment plant; another outlet connected to a silicate cake hopper 35 - for collecting and feeding the amorphous silica cake to a dryer 36.

The silicate cake hopper 35 is connected to a dryer 36 with an outlet to a system for packaging amorphous silica 37, while the silicate cake from the silicate cake hopper 35 is fed evenly to dryer 36 and after drying it transferred to the system for packaging of amorphous silica 37.

After passing certification, the resulting product - amorphous silica - is ready for distribution and industrial use.

The availability of a warehouse for packaged amorphous silica is common.