WO2013043642A2

WO2013043642A2 - Apparatus and method for converting hazardous waste containing unreacted resin and solvents into disposable non-hazardous material

Info

Publication number: WO2013043642A2
Application number: PCT/US2012/055985
Authority: WO
Inventors: Christopher T. Banus
Original assignee: Banus Christopher T
Priority date: 2011-09-23
Filing date: 2012-09-19
Publication date: 2013-03-28
Also published as: WO2013043642A3

Abstract

A hazardous waste mixture including incompletely polymerized resin and volatile solvents from production of artificial stone and similar products is converted into non-hazardous material by passing it through a horizontal reactor, where it is heated in a first zone to just below its polymerization temperature, driving off any solvents with low boiling points, and then heated in a second zone above its polymerization temperature, thereby fully polymerizing the waste while driving off any solvents with high boiling points. An exit dam maintains some waste in the reactor while excess waste flows over the dam and out of the reactor. An airflow can be used to carry away the solvents. Chopping blades can break up the waste into small granules. Agitating paddles can mix the waste with air, dislodge waste from reactor walls, and direct waste to the blades. Compounds needed for complete polymerization can be added through a feeder port.

Description

APPARATUS AND METHOD FOR CONVERTING HAZARDOUS WASTE CONTAINING UNREACTED RESIN AND SOLVENTS INTO DISPOSABLE

NON-HAZARDOUS MATERIAL

Inventor:

Christopher T. Banus

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Applications No. 61/538,377, filed September 23, 201 1 , and 61/567,654, filed December 7, 201 1. Both of these applications are herein incorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

[0002] This invention relates to disposal of hazardous industrial waste, and more particularly to disposal of hazardous waste that contains binders from production of artificial stone, polymer concretes, and other products composed of resinous binders and mineral fillers.

BACKGROUND OF THE INVENTION

[0003] Production of artificial stone and similar products creates waste materials containing binders such as synthetic resins and various solvents, along with aggregates of stone and cullet from glass, mirrors, etc. These hazardous waste materials (HWM), such as resin, solvents (also referred to herein as volatile organic chemicals, or "VOC' s"), and monomers, are a mixture of minerals and organic chemicals, and will often include:

1. Excess quantities of the actual resinous polymer/mineral blend product that is being produced and is left over in the mixing machines or conveyors or forming devices;

2. Polymer/mineral blend product that has been further diluted with various amounts of cleaning solvents, such as acetone, ketones, esters, styrene, and benzene derivative solvents (VOC's), all commonly used to dissolve waste and clean the equipment used in the processing of these polymer and mineral type products; and/or

3. Both of the above materials mixed together.

[0004] Disposal of this hazardous waste material (HWM) is a problem. In many cases it is incorrectly and/or illegally disposed of at non-hazardous material dump sites, and can be destructive to the environment. When properly disposed of at hazardous waste disposal facilities, the disposal cost can be very high.

[0005] Existing methods which attempt to treat the hazardous waste material resulting from production of artificial stone and similar products can be summarized as follows:

1. Heating a container of the waste material until the resin/binder

completes polymerization, with the result being a block or chunk of the hardened waste material.

2. Passing the hazardous waste material through a heated, rotating drum or pipe (sometimes with internal agitation) that results in the material being polymerized to a solid state comprising many large chunks or blocks of material.

[0006] While these two methods do cause some, but not all, of the thermosetting binder or resin components to polymerize to a solid, they suffer from at least three significant problems :

1. The resulting one or more blocks and/or large chunks of polymerized material are difficult to handle and transport.

2. Even when the resulting processed material is in small pieces or

granules, there is always excess styrene, acetone, toluols, and/or other hazardous VOC' s remaining in the polymerized chunks.

3. The resinous material that is polymerized in the waste treatment process is very often not completely polymerized. This is because of uneven heating of the chunky material or the block of material, and also because the waste material entering the disposal process has been collected from various parts of the manufacturing process, so that significant portions of the required styrene in the polyester resin has been lost to evaporation by the time the waste material is treated. As a result, significant quantities of unreacted or partially reacted pre- polymer chemicals are left behind that can leach out of the final treated product. In such cases, the output from these prior art devices is not a non- hazardous waste output, but is instead only a less toxic hazardous waste.

[0007] The result of these methods is therefore to reduce the quantity of liquid resins and binders in the material, but they still contain hazardous quantities of un-polymerized resin and of various cleaning solvents.

[0008] What is needed therefore is an apparatus and method that can reliably convert substantially all of the un-polymerized resin in hazardous waste material (HWM) resulting from production of artificial stone and similar products into a solid state, while removing all hazardous VOC's from the HWM, resulting in a more or less free flowing granular material that can be easily transported to and deposited in a non HWM site.

SUMMARY OF THE INVENTION

[0009] The present invention is an apparatus and method (referred to herein as the Conversion Process [CP]) for converting resinous hazardous waste material resulting from production of artificial stone and similar products into a non-hazardous material that can be easily transported and safely disposed of at low cost in a non-hazardous dump site. The invention assures full

polymerizing of the resins and complete removal of all VOC's, so as to convert the waste into a truly non-hazardous material.

[0010] According to the present invention, raw hazardous waste material from the production of polymer concretes, resin based artificial stone, or other resin and/or mineral composites, is fed continuously into a reactor vessel (also referred to herein as a "processor," a "reactor tube," or an "RT") that is typically shaped as a tube, pipe, or drum having a central axis that is approximately horizontal. Inside the reactor vessel are rotating blades and/or paddles that vertically lift and churn the HWM and dislodge the HWM from the inside walls of the reactor. As HWM material is continuously fed into the reactor, the material moves laterally to the reactor exit. In embodiments, heating elements (which can be of any type known in the art) are applied to the reactor tube so as to increase the temperature of the HWM in a controlled manner as the material passes through the reactor. In this way, the

polymerization temperature for the resin system is reached, the resin polymerizes, and excess VOCs can be drawn off from the mixture.

[0011] The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the

specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1A is a perspective view of an embodiment of the present invention, showing structure within the reactor vessel;

[0013] Figure I B is a perspective view of an embodiment of the present invention that includes heating elements applied to the exterior of the reactor vessel and an air circulation system for vapor exhaust;

[0014] Figure 1 C is a perspective view of an embodiment similar to Figure IB, but including condensers that recover solvents for re-use;

[0015] Figure 2 is a side view of an embodiment that includes a feeding funnel from which HWM is weighed and metered into the reactor vessel, so that an appropriate quantity of styrene can be injected for near-complete polymerization of the HWM; and

[0016] Figure 3 is a chart indicating boiling points of some common solvents.

DETAILED DESCRIPTION

[0017] The present invention is an apparatus and method (referred to herein as the Conversion Process [CP]) for converting hazardous waste material resulting from production of artificial stone and similar products into a non- hazardous material that can be safely disposed of at low cost in a non- hazardous dump site.

[0018] With reference to Figure 1A, raw material as hazardous waste material ("HWM") resulting from the production of polymer concretes, resin based artificial stone, or other resin or mineral composites, is fed continuously through an HWM input port 200 and into a reactor vessel 100 (also referred to herein as a "processor," a "reactor tube," or an "RT") which in some embodiments is shaped as a tube, barrel, or pipe having a selected length and diameter, and having an axis that is at least approximately horizontal. A dam 104 that blocks approximately the lower half of the RT 100 is included in the reactor vessel 100 near its output end 102, so that the laterally moving material is retained in the RT 100 until the material exceeds the height of the dam 104, after which it exist the reactor vessel through the HWM output port 201. The overall throughput of the system is controlled by the feed rate at the HWM input port 200.

[0019] Inside the reactor vessel are rotating agitators 106 such as blades or paddles that vertically churn and mix the HWM while also dislodging the HWM from the inside walls of the reactor tube 100. As new HWM material is continuously fed into the reactor 100, the material moves laterally to the reactor exit 201.

[0020] In some embodiments, the agitator 106 is driven by a horizontal shaft 108 that spans the entire length of the reactor tube 100. In some of these embodiments, the blades or paddles 106 are attached to the shaft 108 (which in some embodiments are plowshare type blades) and the shaft 108 is rotated at a speed that is sufficient to cause the HWM to be aerated, tumbled, and mixed so that more or less the entire diameter of the RT 100 is filled with a mixture of HWM and air, even though the quantity of HWM without the mixing and agitation would only fill the bottom half of the RT 100. [0021] The reactor vessel 100 in various embodiments further includes a feeder 210 or "dosing device" that allows styrene (or other additives) to be injected into the mass of material in the reactor vessel 100.

[0022] In various embodiments, at least one chopper-type propeller blade 1 10 is placed into the wall of the RT 100. The propeller blade 1 10 turns at relatively high rotation speeds compared to the rotating mixer shaft 108. In at least some of these embodiments the paddles and/or plowshare blades 106 are configured to force the HWM to flow into the chopper blade(s) 1 10, thereby further enhancing the system' s ability to maintain the material in a small granule format during the polymerization process. In Figure 1A, the chopper blade 1 10 is centrally located in the RT 100. In some embodiments that include heating elements 1 12, 1 14 which heat the HWM, the chopper blade is placed near the HWM input end 200 of the RT 100, where the styrene dosing injection port 210 is also located. This ensures that any styrene that is added through the styrene dosing injection port 210 will be well mixed into the HWM before the heating begins.

[0023] With reference to Figure IB, embodiments of the present invention include a negative pressure air ventilation system that removes VOC' s released during processing of the HWM. Air is drawn into the upper portion of the reactor vessel 100 at its input end through an air inlet tube 220, and

solvent/resin vapors are removed from at least one vapor outlet tube 221 , 222. In embodiments, the vapor outlet tubes are connected to a factory vapor exhaust system, so that the fumes can be conveyed to a central burner.

[0024] The purpose of this airflow through the reactor 100 is twofold:

1. The continuous flow of air maintains the concentration of flammable fume vapors below the explosive limit; and

2. By using increased air flow, and by matching the quantity of air to the reactor temperatures, the types of solvents (according to their boiling points and vapor pressures) and the types of volatile resin components, it is possible to completely eliminate VOCs from the processed HWM, such that the output polymerized materials do not contain significant amounts of objectionable and/or hazardous VOC's. [0025] The Conversion Process ("CP") of the present invention has two important effects on the aerated, free flowing HWM:

1. Preventing any large lumps of polymerized material from forming as the polymerization temperature is reached. The HWM mixture is maintained as loose, aerated, small granules as the resin hardens, resulting in a more free-flowing output product; and

2. Because the processed HWM is maintained as small granules and easily aerated, then the VOC stripping air can easily remove all the VOC's, some of which might otherwise be trapped inside of larger chunks and/or balls of material, or within a compacted bed of the processed material.

[0026] With further reference to Figure IB, according to embodiments of the present invention heating elements 1 12, 1 14 of any type known in the art are applied to the reactor tube 100 so as to increase the temperature of the HWM in a controlled manner as the waste material passes through the reactor 100. So as to optimize the polymerization of resins, and equally importantly to optimize the stripping out of the VOC' s, the temperature gradient, maximum attained temperature, and HWM dwell time at the maximum temperature are all carefully controlled and adjusted according to characteristics of the particular HWM being processed.

[0027] The first part of the waste material' s transit through the reactor vessel is referred to herein as the pre-polymerization period or dwell time (the "PrePDT"). During this period the material passes through a PrePDT zone 1 16, and the temperature of the material is increased from the raw material input temperature (typically ambient temperature) up to a temperature just below the polymerization temperature (PT). The next stage of the transit is referred to herein as the post polymerization period or dwell time [PostPDT]. During this stage, the material passes through a post-PDT zone 1 18, while the temperature of the material is maintained at or above the resin polymerization temperature.

[0028] In various embodiments, the temperature of the passing HWM is monitored by a temperature sensor 122 so as to control the heating elements 1 12, 1 14. A decrease of temperature in the processing vessel 100 sends a signal to a feeder drive and stops it from adding more raw HWM until the correct temperature has been restored.

[0029] Embodiments of the present invention permit control of the temperature gradient through both the Pre and Post PDT temperature zones 1 16, 1 18, and the HWM dwell time in these zones, so that sufficient time and airflow can be applied to strip out all of the acetone and/or other VOC' s, and/or all of the un-polymerized styrene and/or benzene derivatives, etc. The resulting output product will then be completely polymerized and essentially free of retained VOC's, and thus will be a non-hazardous material with respect to organic resin and solvents.

[0030] In the embodiment of Figure I B, one of the vapor outlets 221 is located approximately in the middle of the reactor tube 100, so that the vapors being removed are those that can be extracted from the HWM mass during the time that HWM is being raised in temperature from ambient to the approximate polymerization temperature. This will allow the extraction of vapors

(particularly acetone and other low BP solvents that are used to clean the production equipment and are now part of the HWM) so that they are removed from the reactor before polymerization begins. Another vapor output tube 222 is provided at the final end 102 of the reactor, so that any VOCs with boiling points that are higher than the polymerization temperature are removed from the HWM mass and from the reactor 100. An air pressure sensor 21 1 is included so that if the low pressure is lost in a vapor removal duct 222, then an alarm can be used to call the operator or the reactor 100 can be adjusted or shut down automatically.

[0031] With reference to Figure 1 C, in some embodiments each of the vapor outlet tubes 221 , 222 is fitted with one or more condensers 224 that can recover the low BP solvents for re-use. If the vapors are from multiple solvents, then a plurality of condensers can be used in series to separate the different fractions. Or a single condenser 224 can be used to condense all of the different vapors together as a mixture. [0032] For some applications, resin polymerization requires an additive with a relatively low boiling point ("BP"). For example, the resin being employed in the production of agglomerated stones or polymer concretes is often some type of polyester/vinyl ester resin that requires styrene as a component of the reaction that forms the cured polymer. Styrene has a relatively low BP, and tends to evaporate from the polymer concrete/agglomerated stone material mixture. This is especially true at the end of a production run when the production equipment must be cleaned, because relatively thinner layers of material are being cleaned from the equipment over some hours. The result can be that there is an insufficient quantity of the styrene (or other required additive) in the HWM, relative to the other resin components such as acid anhydride or polyols, so that during polymerization in the reactor tube 100 the polymerization will be incomplete, and an excess of unreacted components such as polyols and anhydrides will be left over.

[0033] Fig 2 is a side view of an embodiment that includes a feeding funnel 302 positioned over the HWM inlet 200 of the reactor tube 100. The feeding funnel 302 includes an agitator 303 that moves the input HWM, and also includes load cells 301 that weigh the funnel and allow a precise amount of HWM to be metered into the reactor tube 100. As the HWM is metered into the reactor tube 100, an appropriate quantity of styrene (according to actual resin recipes and the degree of styrene loss during the cleaning process) can be injected into the reactor vessel 100 via a feeder 210, thereby restoring and approximately correcting the percentage of styrene included in the resin system, so that a very complete reaction occurs that consumes all of the resin components. In embodiments, the addition and mixing of the styrene (or other suitable monomer depending on the type of resin used) takes place in the Pre- PDT zone 1 16.

[0034] Control of the temperature gradient in each of the pre and post dwell time transit areas 1 16, 1 18 has not previously been taught in the prior art, including prior art methods that use some mixing and/or stirring during polymerization. Prior art heat-as-a-batch methods are also silent regarding a controlled temperature gradient or air flow. Therefore, in previous methods, user control over the process is insufficient to insure that all of the resin will be polymerized, and that there will be sufficient time and temperature exposure to strip off the various VOC' s from the waste, where each species of VOC has its own particular BP and vapor pressure, as illustrated in Figure 3.

[0035] The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.

Claims

What is claimed is: 1. A method for converting a hazardous waste material into non-hazardous granules, the waste material containing an incompletely reacted polymer having a polymerization temperature, the waste material also containing at least one volatile organic chemical ("VOC") having a VOC boiling point, the method comprising:

introducing the waste material into a substantially horizontal reactor vessel;

during a first processing time, transporting the waste material horizontally through a first zone of the reactor vessel and heating the waste material until it reaches a temperature substantially equal to the polymerizing temperature;

during a second processing time, transporting the waste material horizontally through a second zone of the reactor vessel while maintaining the waste material at a temperature at least equal to the polymerizing temperature; and

discharging the waste material from the reactor vessel as granules of non-hazardous, polymerized material.

2. The method of claim 1 , further comprising applying a flow of air to the waste material in the first zone and controlling the first processing time and a temperature profile in the first zone so that any VOC having a boiling point below the polymerization temperature is boiled off and stripped out with the air flow during the transit of the waste material through the first zone.

3. The method of claim 1 , further comprising applying a flow of air to the waste material in the second zone and controlling the second processing time and a temperature profile in the second zone so that any VOC having a boiling point that is equal to or above the polymerization temperature is boiled off and stripped out with the air flow during the transit of the waste material through the second zone.

4. The method of claim 1 , further comprising mixing the waste material with an air flow during the first and second processing periods, so that the waste material is maintained in a free-flowing aerated state and the sizes of the resulting granules of polymerized material are minimized.

5. The method of Claim 4, wherein the air flow is adjusted in volume so as to remove the VOC' s during at least one of the first and second processing periods.

6. The method of claim 1 , further comprising vertically agitating the waste material as it is transported through at least one of the first and second zones.

7. The method of claim 1 , further comprising mechanically chopping the waste material as it is transported through at least one of the first and second zones, thereby reducing sizes of the waste material granules.

8. The method of claim 1 , further comprising adjusting heaters directed to at least one of the first zone and the second zone according to a measured temperature within the reactor vessel.

9. The method of claim 1 , further comprising adding to the reactor vessel a chemical compound that is required for polymerization of the incompletely reacted polymer.

10. The method of claim 9, further comprising:

adding waste material to the reactor vessel in measured and controlled quantities; and

adding the chemical compound in quantities corresponding to the quantities of added waste material, so that the incompletely reacted polymer is fully polymerized and the added chemical compound is fully utilized.

1 1. The method of claim 1 , further comprising:

removing the VOC from the reactor vessel by applying an airflow to the reactor vessel; and

condensing the VOC from the airflow after it leaves the reactor vessel.

12. An apparatus for converting a hazardous waste material into non- hazardous granules, the waste material containing an incompletely reacted polymer having a polymerization temperature, the waste material also containing at least one volatile organic chemical ("VOC") having a VOC boiling point, the apparatus comprising:

a substantially horizontal reactor vessel;

a first heater configured to heat a first zone of the reactor vessel;

a second heater configured to heat a second zone of the reactor vessel; a transport mechanism for transporting the waste material through the first and second zones; and

an exit barrier configured to partially block an exit end of the reactor vessel and maintain a lower portion of the reactor vessel filled with waste material while waste material above the lower portion passes over the barrier and out of the reactor vessel.

13. The apparatus of claim 12, further comprising at least one agitator configured to vertically agitate the waste material and mix it with air as it is transported through the reactor vessel.

14. The apparatus of claim 13, wherein the agitator is configured to dislodge waste material from interior walls of the reactor vessel.

15. The apparatus of claim 12, further comprising at least one chopping mechanism configured to reduce the sizes of granules of waste material inside of the reactor vessel.

16. The apparatus of claim 15, further comprising at least one agitator configured to vertically agitate the waste material and mix it with air as it is transported through the reactor vessel, the agitator being configured to direct waste material to the chopping mechanism.

17. The apparatus of claim 12, further comprising an air circulation system configured to circulate an airflow through the reactor vessel and to thereby remove evaporated VOC from the reactor vessel.

18. The apparatus of claim 17, further comprising a VOC condenser that is configured to condense the VOC from the airflow after it leaves the reactor vessel.

19. The apparatus of claim 12, further comprising a temperature sensor configured for measuring an internal temperature of the reactor vessel and controlling at least one of the first and second heater.

20. The apparatus of claim 19, further comprising a waste material feed controller configured to control a rate of entry of waste material into the reactor vessel according to temperature measurements of the temperature sensor.

21. The apparatus of claim 12, wherein the first heater is able to heat the waste material to a temperature substantially equal to its polymerization temperature.

22. The apparatus of claim 12, wherein the second heater is able to maintain the waste material at a temperature that is at least as high as the polymerization temperature.

23. The apparatus of claim 12, wherein at least one of the first heater and the second heater are able to create and maintain a desired temperature gradient within the reactor vessel.

24. The apparatus of claim 12, further comprising a feeder inlet through which a chemical compound that is required for polymerization of the incompletely reacted polymer can be adding to the reactor vessel.

25. The apparatus of claim 24, further comprising:

a waste material metering device that is configured for metering controlled quantities of waste material into the reactor vessel; and

a feeder controller that is configured to add the chemical compound to the rector vessel in quantities corresponding to the controlled quantities of added waste material, so that the incompletely reacted polymer is fully polymerized and the added chemical compound is fully utilized.