Pyrolysis of halogenated organic hazardous wastes with direct reduction of iron oxides

Disposal of halogenated organic hazardous wastes by introducing them as feedstocks in the direct reduction of iron oxide (DRI). (DRI is described in Pat. RE.32247.) The novel hydrocarbons used as reducing feedstocks would normally be destined to become hazardous wastes or else their products of decomposition would be hazardous wastes. Such hydrocarbons are inclusive of but not limited to halogenated hydrocarbons such as PVC, PCBs, various insecticides, dioxin and others. This category of hydrocarbon wastes is otherwise difficult to utilize, incinerate, or otherwise dispose of safely. Polluting byproducts such as dioxin are almost always released. However within a DRI reactor they can be disposed of safely. There is no stack or vent to atmosphere. These hydrocarbons would be used as an alternative to or admixture with the usual hydrocarbon feedstocks of choice, methane or related short chain hydrocarbons.

BACKGROUND
 1. Field of Invention
 This invention involves decomposition of halogenated organic hazardous
 waste materials into inorganic molecules. The wastes are
 pyrolized/cracked/reformed and reacted with iron oxide in a closed,
 heated, pressurized Direct Reduction of Iron Oxide (DRI) process.
 2. Description of Prior Art
 Direct Reduction of Iron oxide to iron and carburization of that iron to
 iron carbide has been described in Pat. Re. 32247. Methane is the
 hydrocarbon of choice for this process although use of related short chain
 hydrocarbons has been postulated.
 This is a continuation in part of patent application Ser. No. 08/790,527
 issued as U.S. Pat. No. 5,824,134 which teaches decomposition of organic
 hazardous wastes with polluting fractions selected tom a group consisting
 of organic phosphates, organic sulfurs, organic nitrogens, or organic
 mercury or tin.
 Pat. U.S. No. 5,425,792 proposed producing syngas by reforming auto
 shredder and other industrial wastes under high heat in a rotary kiln.
 Pat. U.S. No. 5,244,490 proposed waste polymer materials as part of the
 fuel charge in iron melting blast furnaces. Both processes are done at
 temperatures in excess of 2000 degrees C. and not under the pressures
 customary in a closed pressurized DRI reactor. They vent products of
 decomposition to the atmosphere.
 Pat. U.S. No. 4,834,792 teaches adding excess methane to DRI reactors to
 partially carburize sponge iron to make it less pyrophoric during
 handling.
 German Patent 2841039 apparently teaches the test tube scale reduction of
 metal oxides using Trichlorofluromethane (CFCL3) reagent as a versatile,
 low temperature reducing agent. The present invention is for commercial
 scale safe disposal and reuse of halogenated organic waste materials.
 OBJECTS AND ADVANTAGES
 Accordingly, several objects and advantages of my invention are:
 It provides a significant source of added revenue to the operators of a
 Direct Reduction of Iron Oxide reactor because the novel hydrocarbons used
 as feedstocks would normally be destined to become hazardous wastes or
 else their products of decomposition would be hazardous wastes for which
 disposal is difficult, environmentally hazardous and expensive.
 Suppliers of such feedstocks would pay dearly to a DRI processor to accept
 and consume as feedstock organic hazardous wastes containing organic
 phosphorous, organic sulfurs, organic nitrogens, organic mercury, or
 organic tin but including halogenated hydrocarbons. These materials are
 difficult and expensive to incinerate or otherwise dispose of safely for
 polluting discharges are almost always released.
 A DRI as hazardous feedstock reactor has the advantage that it would
 require much lower net energy and temperature than any of various
 hazardous waste incinerators and is closed, pressurized and therefore
 environmentally safer.
 Carbon is not wasted up a stack as polluting CO.sub.2, but is incorporated
 and shipped with the iron as iron carbide.
 The reactor is essentially a closed pressurized reactor with no polluting
 stack.
 The reaction products are liquid water solid iron, solid iron carbide, may
 include free tin, free mercury and/or inorganic acid gases. Of said
 products, resulting water and inorganic remnants of polluting fractions
 which are scrubbed from the reducing carburizing atmosphere.
 The catalysts that helps crack the hazardous waste molecules do not have to
 be decarburized as does y-zeolite catalyst in petroleum cat crackers since
 the carburized iron compounds functioning as cracking catalyst in the
 fluidized bed (or other DRI reactor) are shipped as the end product.
 Still further objects and advantages will become apparent from a
 consideration of the ensuing description and accompanying drawings.
 SUMMARY
 This process disposes of organic hazardous materials by breaking them down
 into carbon, hydrogen and inorganic forms of the polluting fractions of
 the beginning organic materials. Waste hydrocarbons with associated
 polluting fractions are pyrolyzed/cracked/reformed into progressively
 smaller carbon chains and into CH.sub.4, CO, CO.sub.2, H.sub.2 O, H.sub.2
 and polluting fractions in the reaction zone of the fluidized bed (or
 other DRI reactor) containing iron oxide. The CO and H.sub.2 are required
 to reduce the iron oxide and the CH.sub.4, and CO carburize the metallic
 iron. The water along with polluting fractions; possibly phosphates,
 sulfates, nitrates, or heavy metals such as mercury or tin but
 specifically including acid gases of halogens, can be continuously
 scrubbed from the reducing gases by limestone admixed in the iron oxide
 feedstock, water scrubber in water solution, or in ion scrubbers added for
 that purpose.
 These feedstocks might otherwise be destined to be hazardous waste
 materials. These materials are difficult to incinerate or otherwise
 dispose of safely. Polluting byproducts are almost always released.
 However in this invention the reducing atmosphere is partially scrubbed of
 unwanted remnants of pyrolysis; soluble and condensed acid gases with
 condensed water vapor in the direct reduction water scrubbers. The
 reaction products in such a DRI reactor are inorganic, collectable, and
 safely reusable or disposable. Suppliers of such feedstocks would pay
 dearly to provide such hydrocarbons to a DRI processor to save disposal
 costs. This would add to that processors revenues and avoid the need to
 purchase some or all the usual methane feedstock.

REFERENCE NUMERALS
 10 mixed hydrocarbon feedstock; would-be wastes plus optional methane
 12 iron oxide feedstock with crushed limestone admixture
 14 Main Reactor
 16 iron carbide product
 18 wet reducing(carburizing gases and polluting fractions
 20 reducing/carburizing gases with polluting fractions and water removed
 22 scrubber designed for more corrosive gases
 24 ion columns supplanting condensed water solutions for removing
 pollutants
 26 contaminant/water solution discharge
 28 discharge from columns
 30 surrounding pressure vessel
 PREFERRED EMBODIMENT
 Hydrocarbons with associated polluting fractions 10 (mixed with or without
 the usual methane) are pyrolyzed/cracked/reformed progressively into hot
 CH.sub.4, CO, CO.sub.2, H.sub.2, and H.sub.2 O mixed with polluting
 fractions 18 within the reaction zone (Main Reactor) 14 a fluidized bed
 (or other DRI reactor) of iron oxide. The CO and H.sub.2 20 reduce the
 iron oxide 12 when it enters the reactor and the CH.sub.4 and CO 20
 carburize the metallic iron into iron carbide product 16. Polluting
 fractions are also cracked from the hydrocarbons with associated polluting
 fractions. Such materials including halogens, phosphates, sulfates,
 nitrates, and heavy metals can be continuously scrubbed in situ by
 limestone 12 admixed with iron oxide, scrubbed 22 from the reducing gases
 in water solution 26 and/or in ion scrubbers 24 and 28 added for that
 purpose. All reactions are confined to the surrounding pressure vessel 30.
 CONCLUSIONS, RAMIFICATIONS, AND SCOPE
 Accordingly, it can be seen that I have provided a closed and clean method
 of decomposing halogenated organic hazardous wastes into manageable
 inorganics that is clearly environmentally safer than open methods like
 fuel blending or incineration. Inorganic halogen acid gas ions can be
 scrubbed to be reused or tied up as safe salts (such as CaCl2) that can be
 properly disposed.
 Although the description above contains many specificities, these should
 not be construed as limiting the scope of the invention but as merely
 providing illustrations of some of the presently preferred embodiments of
 this invention. Various other embodiments and ramifications are possible
 within it's scope. For example products of decomposition of medical
 hazardous wastes include organic hazardous materials, in fact are a major
 dioxin source. By this process such materials are converted to more docile
 inorganic materials. Plastic wastes or tires, could also be used as
 organic hazardous material feedstocks wherein organic products of
 decomposition of said materials are converted to less harmful inorganic
 materials. Thus the scope of the invention should be determined by the
 appended claims and their legal equivalents, rather than by the examples
 given.