FI94569B - Method and apparatus for treating glass articles containing harmful substances - Google Patents

Description

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The present invention relates to a method 5 according to the preamble of claim 1 for treating fluorescent tubes and similar articles containing mainly harmful substances, mainly glass, so that the dangerous substances contained therein can be treated as harmless.

The invention also relates to an apparatus 10 according to the preamble of claim 7 for carrying out the method.

Various lighting devices, such as fluorescent tubes and sodium lamps, contain toxic substances, which is why used lamps become hazardous waste when they are exhausted. The same problem occurs with mercury thermometers, picture tubes, circuit breakers and 15 other devices that contain substances that are hazardous to the environment. If such a device breaks, the harmful substance it contains enters the environment, whereby the mercury contained in fluorescent tubes, for example, enters nature and is easily converted by microbes to methylmercury, which is toxic and is known to be easily enriched in the food chain.

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Several different processes have been developed for the treatment of mercury-containing waste. The processes are practically divided into two different types, evaporation processes and wet processes. In evaporation processes, the mercury is evaporated and condensed, i.e. dry distilled. With this process, the mercury is quite well separated and the final 25 is mercury of reasonably pure, which can be reused. In wet processes, objects containing mercury or other harmful substances are broken down inside the liquid and washed, whereby an attempt is made to remove the mercury into the washing liquid. Mercury dissolved in the liquid is precipitated into a metal salt precipitate, whereby the mercury is in a sparingly soluble form and no longer poses an environmental risk.

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In one known method, the fluorescent tubes to be treated are sorted and placed manually in the feed apparatus, after which the ends of the tubes are cut off and their inner surface 2 94569 is cleaned by air blowing. The phosphor and mercury are on the inner surface of the tubes as a dusty layer that travels with the blown air in closed containers from which the air is filtered through activated carbon filters to the outside air. The glass and metal parts of the pipes are recycled. The disadvantages of this method are the sorting and arrangement of the pipes, which requires a lot of 5 crafts, and the rather poor cleaning result obtained by air blowing. The quality of the filtered air must be constantly monitored and the filters must be replaced periodically to prevent mercury from entering the environment. The filters used are an environmental risk because the filtered substances in them are not bound to chemically harmless compounds.

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The waste batch to be treated in the dry distillation processes is placed in a distillation chamber, the temperature of which is raised to 400-500 ° C and to which a vacuum is sucked by a vacuum pump. Mercury evaporates and escapes from the waste and can be flushed out of the chamber with the air stream. From this air stream, organic matter is combusted at about 800 ° C and the gas is cooled to a relatively low temperature, whereupon the mercury condenses and separates from the gas stream.

The spent carrier gas must be further purified, for example by activated carbon filtration, and removed from the system via a vacuum pump.

The dry distillation process is slow and requires a lot of energy, because the material to be treated and the vacuum chamber 20 have to be heated to a high temperature for each batch and, after distillation, cooled again, whereby energy is wasted. To increase the capacity, a sorting apparatus has been developed in which glass tubes are crushed, coarse glass and metal are separated from fine glass crumb by a vibrating screen and only the fine material is treated by distillation. This can be done because the mercury is mainly attached to the finely divided material and the coarser material can be recycled without further treatment. This major weakness of the method is its batch performance and the fact that significant amounts of mercury may be released into the environment with coarse material.

30 One wet process in operation operates by placing the pipes to be treated in a basin which is filled with liquid so that the pipes are below the surface of the liquid.

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Next, the pipes are crushed by pressing the crushing plate at the top of the basin towards the bottom of the basin during the loading phase, whereby the pipes break. Metals and metal vapor are bound in the liquid to sulfides. The crushing equipment is placed on the platform of the car and is emptied into a special tank and the contents of the tank are handled at the central station. The weakness of this equipment 5 is its batch performance and the fact that the crushed mass and liquid have to be transported by special equipment. The equipment is thus suitable for receiving small fluorescent coils, for example in residential suburbs, but not for continuous industrial handling of objects containing hazardous substances. Of course, the equipment can also be built fixed, in which case its main weakness is still the batch-based treatment method.

It is an object of the present invention to provide a method and apparatus by which fluorescent tubes and the like can be treated efficiently and continuously while cleaning the resulting glass and metal waste to a high degree of purity.

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It is a further object of the invention to provide a method and apparatus by means of which objects of different types and shapes containing various harmful substances can be treated.

The invention is based on the fact that the objects to be treated are fed through a liquid curtain to a crusher, where they are broken and the resulting crush is washed with pressurized liquid jets, after which the glass and metal are separated from the liquid and treated to neutralize and separate hazardous substances.

More specifically, the method according to the invention is characterized by what is set forth in the characterizing part of claim 1.

The device according to the invention, in turn, is characterized by what is stated in the characterizing part of claim 7.

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The invention provides considerable advantages.

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The most economically important advantage of the invention is its continuous operation. Continuous operation achieves the lowest possible need for energy and labor. The crushing and washing of the objects to be treated are completely separated from the environment and are fed intact for crushing. As no hazardous fumes or other substances hazardous to health are released from the equipment, the method guarantees good occupational safety.

The cleaning time can be adjusted and the equipment can be used to achieve very low residue levels. The mercury contents of the treated glass and metal are in the range of 6-2 mg / kg, so that the final products can be well reused. The spent water is also very well purified from mercury and could even be drained directly, but it is preferably recycled back into the water curtain and wash water, leaving a small amount of water leaving the process. This small amount of water leaves the ice system only with the glass and metal crush and the filtered precipitate. The equipment and method can be applied to a wide variety of objects and substances without structural changes.

However, it is clear that the treatment chemicals must be selected according to the substances contained in the articles. An additional advantage of the invention is that it can be built modular, so that it can be easily moved if necessary. This is of particular benefit when building new equipment, as the equipment can be pre-assembled and fully tested before delivery to the customer.

The invention will now be described in more detail with reference to the accompanying drawings.

Figure 1 is a block diagram of a process according to the invention.

Figure 2 is a process diagram of a process according to the invention.

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Figure 3 is a more detailed schematic diagram of the equipment at the beginning of the process.

The block diagram of Figure 1 shows the outline of the processing process according to the invention. The intact fluorescent tubes are first fed for crushing, where their glass parts 30 are crushed and the aluminum bases are compressed and separated from the glass. The pipes are fed for crushing through a water curtain so that any hazardous vapors that may be released from the pipes during crushing do not enter the environment. The crushed material resulting from the crushing is washed with pressurized water jets, the washed crushed stone is separated from the water and the glass and aluminum bases contained in the crushed stone are separated and delivered for recycling to a glass or glass wool mill and scrap shops.

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The next step in the process is to treat the water used in the previous steps for the water curtain and wash, in which the mercury and phosphores have been mixed. The pH of the water is first adjusted by adding a base to suit the next steps and then a precipitating chemical is added to the water. The precipitation step may involve various auxiliary treatments, of which flocculation is shown in Figure 1. After precipitation, the water is led to a clarification tank and the excess water from the clarifier is returned to the water curtain or wash water at the beginning of the process. The pH of the excess water is adjusted by adding acid to the water. The clarifier bottom, which contains the metal precipitate, is passed to a filter, from which the filtrate water is returned to the water curtain and wash, and the mercury-containing precipitate is removed to a thief-15 site suitable for transport.

Figure 2 illustrates the process in more detail.

The devices described in the following description represent only one possible alternative to the most preferred embodiment of the invention shown in Figures 20 2 and 3 at each process step. Alternative hardware solutions for different parts of the process are presented at the end of the «explanation.

The handling of the fluorescent tubes in the apparatus begins with the placement of the fluorescent tubes in the dispenser 29 of the conveyor 1. The dispenser 29 is a downwardly tapering box with a bottom inclined towards the beginning of the conveyor and an opening at the edge of this inclined bottom. The belt of the conveyor 1 is rubber and has, at regular intervals, transverse comb-like recesses 30 which pick up one tube at a time from the dispenser on the conveyor 1. The conveyor 1 is mounted obliquely and raises the fluorescent tubes in a transverse position to the top of the into the throat of a two-roll roller 6 94569 crusher placed at the bottom. The conveyor 1 and the crusher hopper 2 are completely enclosed, so that no dangerous substances can escape from the enclosure into the environment. The roof of the housing of the crusher hopper 2 has a hatch through which objects of a different shape from the fluorescent tubes can be fed into the hopper 2.

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At the upper end of the conveyor 1 there is a curtain assembled from plastic strips through which the fluorescent tubes pass. The purpose of the curtain is to prevent water and cullet from splashing onto the conveyor 1. In the crusher hopper 2, the fluorescent tubes pass through the water curtains formed by the two rows of nozzles 4. The rows of nozzles 4 are placed in a recess in the wall 10 of the crusher hopper 2 and each nozzle forms a horizontally applied fan-shaped jet. The jet fans are directed obliquely downwards and overlap at their edges so that at the wall of the crusher hopper 2 the water curtain is intact and thus prevents the passage of vapors through the curtain. The nozzles 4 are arranged in two overlapping rows, so that the pipes have to pass through two water curtains when they fall into the hopper 2. The location of the lower water curtain is chosen so that the longest pipe to be treated fits vertically between the crusher 3 and the lower water curtain. completely below the water curtain, so that no dangerous substances can pass through the water curtains from the ruptured pipes.

At the lower end of the crusher hopper 2, the pipes enter the crusher 3, which consists of two parallel rotating rollers. The outer surface of the rollers has longitudinal grooves that pull objects that enter the throat between the rollers between the rollers and crush them.

The distance between the rollers must be adjustable between 2 and 25 mm and the distance must be adjusted so that the rollers break the glass into uniform pieces and flatten the aluminum ends of the fluorescent tubes slightly. Further processing of a uniformly sized crushed stone is easier than a crushed stone with a large particle size distribution.

After the crusher 3, the glass pieces, the aluminum parts and the water coming from the water jets 4 enter the pipe 5, which leads to the lower end of the washing drum 6. The crushed material is transferred to the put-30 chamber with 5 pressurized water jets. The washing drum 6 is adjusted to a slightly oblique position and its angle can be changed to adjust the washing process. At the lower end of the drum 6 there is an opening 7 94569 and an outlet 7 through which the washing water and the water entrained by the crumb are discharged from the drum 6. In front of the outlet 7 there is a barrier plate 31 which prevents the debris from passing away from the drum 6. The inner surface of the washing drum 6 has lifting vanes 32 at its lower end about 1/3 of the length of the drum 6, which move the crushed material coming to the lower end of the drum 6 upwards on the circumference of the drum 6 as the drum rotates. During processing, part of the crushed material in the drum 6 is under water at the bottom of the drum and part has risen as an oblique layer raised by the lifting vanes 32 against the inner surface of the drum.

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In the middle of the washing drum 6 there is a tube 8 with a row of washing nozzles 33 directed towards the layer above the crushed water. The debris is washed in the drum so that the lifting vanes 32 move the debris from the bottom of the drum 6 and the high-pressure water jets from the washing pipe 8 wash the debris against the wall of the drum.

15 The washing effect is enhanced by the abrasion of the crushed particles when mixed together, so the cleaning effect is good.

at the top of the washing drum 6 and the inside of the portion having no lifting vanes 33, is composed of segments in a lifting coil 34, which transfers the washed aggregates wash basket June 20 at the upper end. The washing tube 8 extends over almost the entire distance of the lifting thread 34 and the washing of the particles continues on this part of the drum 6 as well. The residence time of the particles in the drum and its parts and thus the washing effect can be adjusted in many ways. The lifting vanes 33 at the lower end of the drum are oblique and always feed the crush to be treated slightly upwards in the drum. The angle of the vanes 33 can be adjusted and in this way 25 the residence time of the crushed stone in the actual cleaning step is adjusted. The desired cleaning time is about four minutes, whereby as the drum rotates 8 revolutions per minute, each particle is exposed to a jet of pressurized water and, in theory, the mixing cycle is rotated 32 times in the cleaning section. In this way, a multi-stage washing operation can be carried out in a continuous drum. At the beginning of the lifting thread there is an adjustable segment, the angular position of which adjusts the amount of crushed material to be lifted from the cleaning part into the thread 34. This amount should be adjusted to be approximately equal to the amount of untreated crushed material entering drum 8 94569 6. The crushed particles remain in the lift coil section 34 for about two minutes, where they are exposed to a further 16 times the pressurized water jets. The residence time of the crushed material in the drum can be further adjusted by changing the tilt angle of the washing drum 6. Suitable positions of the adjusting members are most easily determined by practical experiments.

The crushed material entering the upper part of the washing drum 6 leaves the drum 6 through 9 and next enters the screen drum 10, where the glass crumb is separated from the aluminum tube ends. The screen drum 10 is a tilted drum, the casing of which is made of steel blood-10 with holes of suitable size. The crushed stone enters the upper end of the drum and begins to travel towards the lower end of the drum 10, whereby glass crumb with a particle size smaller than the ends of the aluminum fluorescent tubes falls through the drum 10 shell onto the conveyor 11. and further to the metal scrap container 14. The conveyors 11 and 13 may be any known conveyors and standard containers of suitable size may be advantageously used as collection containers. The separated material can be delivered directly in containers for recycling.

The water leaving the washing drum 6 is treated as follows. The wash water is pumped into the settling tank 17 along the line 15 by means of a pump 16. Prior to precipitation, the pH of the solution is adjusted to suit the precipitation. The pH is adjusted by adding lye (10%) via a metering pump. The required lye is fed to the suction side of the transfer pump 16. whereby it mixes well with the washing water. In the precipitation tank 17, a precipitant is added to the water, as a result of which mercury and other heavy metals react to sparingly soluble salts. Sodium sulfide, dithiocarbamate or trimercaptotriazine or another suitable substance is used as the reagent. The latter is sold under the trade name TMT15. The water is mixed with a mixer 18 to mix the precipitant and the water well and the residence time of the water in the tank 17 is about 10 minutes.

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Add the required amount of precipitating reagent to the precipitation tank. The precipitant dosing pump 9 94569 is adjusted manually or automatically according to the water supply speed. The mercury content of the wash water correlates with the feed rate of the precipitant. There is normally an excess of precipitating reagent in the process to ensure that all the mercury reacts with the precipitating agent.

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From the precipitation tank, water is led to the instant mixing chamber 19 and the coagulation chemical is dispensed into the water line leading to the rapid mixing chamber. As the coagulation chemicals, normal water treatment chemicals such as ferrous sulfate, ferric chloride or lime can be used. At this point, the mixture is stirred vigorously with a high speed mixer 20 to effectively mix 10 different chemicals into the water. From the mixing vessel 19, water flows as a flow to the actual flocculation tank 21, a flocculation chemical is added to the overflow and the mixture is further gently stirred in the tank with a mixer 22. Normal water treatment chemicals such as polyacrylamide can be used as the flocculation chemical.

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From the flocculation tank 21, the solution flows to the clarifier 23, where the precipitate settles to the bottom of the clarifier 23. The clarification excess flows overflow into the fresh water tank 24, from where it is further pumped back to the scrubber and water curtain along pipelines 25 and 26. The clean water space has a surface switch that adds water to the process with a solenoid valve open-20 clubs.

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The clarifier is removed from the clarifier and passed, for example, to a pressure plate filter 27, where the cake accumulates on the outer surface of the plate. From the vertical plate, the precipitate is easy to remove by blowing air or rinsing with water. The precipitate is collected in a precipitate 25 and the filtrate is returned to the clean water space 24 of the clarifier 23.

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The mercury content of intact fluorescent tubes is estimated to be about 100 ppm, although it varies and has been constantly reduced.

30 The process and its various stages have been extensively studied in laboratory experiments. The experiments have specifically examined mercury concentrations. According to the experimental analyzes, the main concentrations of mercury 10 94569 in the products obtained from the washing process are as follows: 1. Crushed glass

The mercury content of the glass is less than 6 mg / kg and the glass can be sent as such for re-use, e.g. to a glass wool factory.

2. Aluminum sockets for fluorescent lamps

Aluminum has a mercury content of less than 4 mg / lg and can be reused and sent to a scrap yard or smelter.

10 3. Glass dust-containing precipitate This precipitate contains mercury, which is washed from fluorescent tubes, as well as fluorescent substances. Fluorescent substances are not dangerous for the environment. The metals are precipitated as sulfides or mercury-TMT compounds or other compounds that are very insoluble in water and do not react with other substances and are therefore harmless to the environment. According to the tests performed (NO shaking test), the precipitate is suitable for landfill.

Only water is removed from the process with the above products, ie very little. The mercury content of clarified or filtered water is less than 0.005 mg / l, so it can also be drained if necessary (eg maintenance measures) in accordance with Finnish recommendations.

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It is clear that the equipment can be modified in many ways within the scope of the claims. The conveyor feeding the objects to be treated to the crushing hopper 2 can be implemented in many ways and can even be omitted, whereby the objects can be fed to the hopper 2, for example by hand. However, it is preferred that the feeding of the pipes through the water curtain 4 is carried out in such a way that the objects pass through the curtain at short intervals, whereby the curtain remains as intact as possible. A single water curtain is sufficient to provide a reasonable closure, but there are preferably two and possibly more curtains.

30 The shape and construction of the crusher hopper 2 can vary within wide limits. The crusher na 3 can alternatively be a single-roll crusher or a jaw crusher, but continuous crushers such as roll crushers are best suited for the continuous equipment according to the invention. The washing drum 6 can be replaced by other ice systems, in which several successive jets of pressurized water can preferably be applied to the crushed stone. One possible option is a combination of a vibratory conveyor and 5 transverse water jets. The screen drum 10 can, of course, be replaced by various screens and other separators, but here too a drum-type solution is the best because it makes it easy to implement a continuous separation economically.

10 The chemical treatment of wash water is well known per se and several different treatment chemicals are known. One skilled in the art will be able to select the appropriate chemicals and their amounts according to the particular substance being treated. From the point of view of the invention, the most essential feature of this step of the process is the recirculation of water, whereby water consumption is reduced and sewage drainage is avoided. Detergents or other chemicals can be mixed into the water curtain and the washing water if desired, but this is not necessarily necessary, because the invention achieves a sufficiently good washing result even without them.

Not all of the elements mentioned in the above example are necessary for the invention, but can be easily formed into various combinations within the scope of the claims.

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Claims (13)

A method for treating glassware containing harmful substances, comprising: 5 - feeding the articles to an encapsulated crushing apparatus (2, 3), - crushing the articles with a crushing apparatus (2, 3), and 10. treating the crushed stone to clean and separate harmful substances from the crushed material, characterized , that 15. the objects to be treated are fed to the enclosed crushing apparatus closed by at least one liquid curtain through the liquid curtain so that the objects are crushed in the apparatus only after they have completely passed through the liquid curtain, and 20. the crush is cleaned by applying a high-pressure liquid jet at least once. A method according to claim 1, characterized in that the crushed stone is cleaned by rotating it in a washing drum (6) and applying at least one high-pressure liquid jet to the crushed stone due to the rotational movement on the wall of the drum (6). Method according to one of the preceding claims, characterized in that the objects to be treated are fed to the crushing plant (2, 3) individually by a continuous conveyor (1) which feeds them to the top (2) of the crushing plant, from which they fall freely into at least one liquid curtain (4). through the crusher (3). 13 94569 A method according to claim 2, characterized in that the washing liquid is separated from the crushed stone in a washing drum (6) and the crushed material is fed to a separating apparatus (10) in which the glass and metal contained in the crushed stone are separated from each other. A method according to any one of the preceding claims, wherein the crushed water is purified by water and the harmful substances contained in the water are precipitated and the formed precipitate is separated from the water by clarification and filtration. The purified water separated by clarification and filtration is returned to the water curtain and wash water. 10 A method according to claim 4, characterized in that the objects to be treated are fed to the crushing equipment, crushed, cleaned, the cleaning liquid is separated from the crushed stone and the crushed material is sorted continuously. Apparatus for treating glassware containing harmful substances, comprising: - an encapsulated crushing apparatus (2, 3) for crushing objects, and 20. devices (6, 7, 8) for cleaning the crushed material and separating the harmful substances from the crushed material, characterized by at least one nozzle row ( 4) to provide a liquid curtain with which the housing of the crushing apparatus (2, 3) is closed and through which objects can be fed into the crushing apparatus and the distance from the crushing members of the crushing apparatus is so large that the objects to be crushed fit intact between the liquid curtain and the crushing means , 3) a space 14 94569 (6) located below, into which the crushed stone can be fed and which has at least one nozzle (8) for applying a high-pressure liquid jet to the crushed material to be cleaned. Apparatus according to claim 7, characterized in that the space into which the S crumb can be fed is a rotatable washing drum (6) with a plurality of fixedly mounted nozzles (33) for directing a jet of liquid onto the crush to be cleaned. Apparatus according to Claim 8, characterized in that the washing drum (6) is arranged in an oblique position relative to the horizontal. 10 Apparatus according to claim 9, characterized in that a lifting blade (32) is arranged on the inner surface of the washing drum (6) at its lower end to lift the crush to be cleaned onto the wall of the drum (69) and to guide it upwards in the drum. Apparatus according to claim 10, characterized by a lifting thread (34) on the inner surface of the washing drum (6) at its upper end for feeding crushed material upwards in the drum (6). Apparatus according to one of the preceding claims 7 to 11, characterized by a conveyor (1) for feeding the objects to be treated to the crushing apparatus (2, 3), the conveyor (1) comprising an endless belt with transverse cavities (30) for the individual objects to be treated. for picking up and transporting one by one to the crushing equipment (2, 3). 12 94569 Apparatus according to one of the preceding claims 8 to 12, characterized by a washing liquid outlet connection (7) of the washing drum (6) and a blocking plate (31) arranged in the drum (6), by means of which crushed material is prevented from entering the discharge connection. 15 94569