EP0999878A1

EP0999878A1 - Method for eliminating halogenated and non halogenated waste

Info

Publication number: EP0999878A1
Application number: EP98940244A
Authority: EP
Inventors: Guy Rollinger
Original assignee: Pac Holding SA
Current assignee: Pac Holding SA
Priority date: 1997-07-23
Filing date: 1998-07-20
Publication date: 2000-05-17
Anticipated expiration: 2018-07-20
Also published as: JP2001510814A; CN1265043A; ES2172185T3; ATE213657T1; DE59814426D1; EP1219324B1; RU2200601C2; US20030149325A1; EP0999878B1; US6645449B2; PT999878E; CN1198669C; LU90191A7; DE59803209D1; ES2337769T3; HK1047900B; DK1219324T3; EP1219324A3; EP1219324A2; CA2295907A1

Abstract

Process for disposing halogenated and non-halogenated waste comprises reacting the waste with products containing metal oxide with exclusion of oxygen at 800-1100 degrees C.

Description

METHOD FOR THE DISPOSAL OF HALOGENATED AND NON-HALOGENATED WASTE

The present invention relates to a method for the disposal of halogenated and non-halogenated waste materials. Substituted, especially halogenated hydrocarbons, such as those present in carbon tetrachloride, chloroform, methylene chloride, tetra- and trichlorethylene, tetrachloroethane, PCB etc. but also in PVC or polyvinylidene chloride, are a more or less problematic toxic or hazardous waste after use Disposal applies. Substances that are highly toxic to the environment and humans, such as halogenated compounds, especially polyhaiogenated substances such as PCBs or TCDD / TCDF (dioxins / furans) cannot be easily recycled and must be disposed of in an environmentally friendly manner.

They are disposed of either by landfill or by incineration on the high seas or in the country in high-temperature furnaces with an excess of air.

The energy requirement is not insignificant in many cases, since not only do the substances to be removed evaporate and heat them to the required decomposition temperature, but also enormous amounts of air have to be heated. Either pollution of the atmosphere and the risk of acid rain are accepted, as with combustion on the high seas, or extremely expensive systems for air pollution control are required.

From DE-A-33 13 889 a method or a device for eliminating poison and hazardous waste is known, in which the toxic waste materials are mixed with an electrically conductive substance, in particular in the form of iron powder and / or coke, and placed in an induction furnace on the Decomposition temperature of the toxic and / or hazardous waste to be removed is brought.

US-A-4,435,379 describes a process for the decomposition of chlorinated hydrocarbons with metal oxides with the aim of all carbon atoms in To transfer carbon oxide. It is important to use elemental chlorine

To provide conversion of hydrogen groups to HCI. The total ratio of chlorine to hydrogen groups must be at least 1: 1 in order to be able to produce metal chloride. US-A-4,587,116 describes a similar process in which nitrogenous waste can also be disposed of. The heating also takes place from the outside and not from the inside.

EP 0 306 540 describes a process for the production of energy from substituted hydrocarbons, such as those e.g. as CCI4, CHCI3, C2H2CI4, PCB, PVC, polyvinylidene chloride etc. in pure or bound form. The waste material is thermally decomposed in an inductively heatable reactor in the presence of a metal oxide which is difficult to smelt and an electrically conductive material, for example electrode coke or electrographite, and in contact with water vapor at temperatures between 800 and 1,100 ° C. A proportion of the metal oxide that corresponds to the chlorine content of the waste materials is converted into volatile metal chloride. A portion of the released carbon is converted into carbon monoxide and the portion of the carbon that does not react with the metal oxide is converted into water gas (CO + H 2) with the aid of a stoichiometric amount of water vapor.

The object of the present invention is to develop a method which allows various halogenated and non-halogenated waste materials to be disposed of in an environmentally friendly manner.

This object is achieved according to the invention by a process for the disposal of halogenated non-halogenated waste materials, in which the halogenated and non-halogenated waste materials are reacted with metal oxide-containing products with the exclusion of oxygen at temperatures of 800 ° C. to 1100 ° C.

The process described here is used for the environmentally neutral recycling of halogenated and non-halogenated waste materials. The volume of the waste used is largely reduced, so that as few residues as possible remain and the largest possible amount of metals / metal compounds is obtained. The aim is to achieve the most positive energy balance possible during implementation. In a preferred embodiment of the process, carbon-containing, halogenated waste materials are reacted.

In an advantageous embodiment of the method, carbon dioxide is added as the fluidizing gas.

Furthermore, the reactor can also be charged with carbon in the form of graphite and / or coal.

A halogenatable product containing metal oxide is preferably used as the metal oxide-containing starting material.

In a specific embodiment of the process according to the invention, products which contain CaO, T1O2, SiO2, Al2O3 and / or Fβ2O3 or a mixture thereof are used as halogenatable, metal oxide-containing reactants.

Various metal oxide-containing waste materials such as e.g. Silicon-containing residues from the metalworking industry, filter dust, fly ash, fly sands, pile of heaps, electroplating sludge, slag, slate residues etc. are used. Simple quartz sand, which consists of about 98% silicon dioxide (Siθ2), is the simplest material imaginable

Implementation can be used.

All of the above materials are characterized in that they contain a relatively high content of halogenatable metal oxides (CaO, SiO2, TiO2 _> I2O3, Fe2O3, etc.).

This has the advantage that substances containing metal oxides that were previously unavailable for economical use are now being used. As halogenated waste materials, solvents such as: carbon tetrachloride, chloroform, methylene chloride, tetra- and trichlorethylene, tetrachloroethane, coolants or refrigerants, PCB, pesticides, fungicides and herbicides, halogenated plastics such as PVC can be used. A proportion of the metal oxide that corresponds to the chlorine content of the waste materials is converted into metal chloride by the above-mentioned process. Ecologically and economically valuable metal chlorides are formed, with silicon and titanium tetrachloride (SiCIφ TiCl4> being particularly preferred products.

Among other things, Used oils, lubricants, greases, varnishes, paints, tars, waxes, plastics, coolants and solvents, brake fluid or similar non-halogenated substances and materials must be disposed of.

The reaction or reaction products formed thermodynamically preferred under these process parameters are primarily gaseous hydrogen (H ₂ ) in addition to lower percentages of methane (CH). The formation of environmentally hazardous or polluting, gaseous substances such as carbon monoxide (CO), and the carbon dioxide (CO ₂ ) known as so-called greenhouse gas, is negligible under the preferred reaction conditions. Only at temperatures above 1100 ° C can CO or CO _{2 be} formed by chemical decomposition processes. The implementation takes place in a fluidized bed reactor. This can either be made of special ceramics, silicon carbide (SiC) or specially alloyed steels.

The reactor can be brought to the necessary operating temperatures either by using electrical heating elements (e.g. heating halves) or by using induction heating. The temperatures required for the implementation are in the range of 800 ° C to 1100 ° C. The reaction itself takes place with the exclusion of oxygen. Carbon dioxide (CO2) is used as the fluidizing gas.

The halogenated compounds are broken down into their simplest components by the high temperatures, in the case of chlorinated hydrocarbons hydrogen chloride, hydrogen, alkanes and chlorine gas are formed. The chlorine gas and the hydrogen chloride serve as chlorinating agents for the metal oxide-containing products or wastes. Products of this chlorination reaction are the thermodynamically preferred metal chlorides. In addition to the chlorides, hydrogen and carbon monoxide are formed, which can be used as synthesis gas either for the production of electrical energy or for other chemical syntheses, such as methanol synthesis.

Reaction equation 1 The carbon dioxide (CO2) used as the fluidizing gas is completely converted to carbon monoxide (CO) by reaction with the carbon of the decomposed hydrocarbons and by an additional bed of carbon or graphite in the head of the reactor.

In this context one speaks of the so-called BOUDOUARD reaction:

C0 ₂ + C τ 2 CO

Reaction equation 2

The formation of environmentally harmful compounds such as dioxins, furans or, for example, phosgene (COCI ₂ ) is extremely unlikely under the prevailing reaction conditions. All halogenated metal compounds produced are initially in gaseous form. Depending on the starting material, solid, ie crystalline metal compounds can be obtained by cooling to room temperature, or liquid metal compounds by condensation at low temperatures.

The purity of these compounds is 96% and can e.g. by fractional distillation, or rectification.

Various configurations of the invention will now be described below with reference to the accompanying figures. It shows: Fig. 1: a diagram of the plant for the disposal of halogenated waste.

1 shows a feed line 1 for the halogenated waste materials, a feed line 2 for products containing metal oxide, and a line 3 for discharging unreacted materials 3. A fluidization gas ( CO2) is blown into the fluidized bed reactor 5.

The reactor 5 is heated by means of a reactor heater 6 to a temperature between 800 ° C and 1100 ° C, so that there is a reaction between the halogenated waste and the metal oxide-containing substances in the reactor. The products formed are separated in a solid separator 7 and the solid metal chlorides formed, in particular AICI3 and FeC ^, are over a

Line 8 discharged. The remaining gases are cleaned by an activated carbon filter 9 and then compressed by a blower 10. The gases are then cooled in a cooling container 12, which has a coolant inlet 11 and a coolant outlet 13, so that the remaining metal chlorides are eliminated. It is mainly SiCIφ

The gases are then fed to a condenser 15 and in one

Gas wash column 16 subjected to an alkaline gas wash. The column 16 has a circulation pump 17 for the washing liquid. The remaining synthesis gas, a mixture of CO and H2, is via line 18 in the upper

Part of the gas scrubbing column 16 discharged.

As a practical application example, the disposal of perchlorethylene (C-2CI4) and vinyl chloride (C2H3CI, monomer of polyvinyl chloride) as halogenated waste is given. The implementation takes place with slate waste from slate plate production as a product containing metal oxide.

Table 1: Slate analysis from Martelange, Belgian-Luxembourg border area

Before processing, the slate waste is crushed using a jaw crusher. Average grain sizes in the range of 3 - 8 mm are advantageous.

Application example 1: Disposal of PER

The ground slate can be introduced into the reactor by spraying with the fluidizing gas carbon dioxide (CO2). Another feed on

Fluidizing gas is used to generate and maintain the

Fluidized bed. An amount of about 20 - 27 m ³ CO2 is used as an hour

Fluidizing gas supplied.

The temperature of the fluidizing gas is advantageously brought to about 500 ° C. Perchlorethylene (C2CI4, ^' PER) is used as the halogenated waste product.

The PER is introduced as a kind of aerosol from a partial fluidization gas stream directly into the reaction zone of the reactor. There the PER is broken down into its components. The difference between PER and others Solvents is that there are no hydrogen atoms in the molecule. As a result, the formation of hydrochloric acid (HCI) is not possible.

However, chlorine gas (Cl ₂ ) is formed, which is an excellent

Chlorinating agent. The chlorine gas reacts in the fluidized bed with the formation of metal chlorides (generally Me _x C) with the metal oxides of the slate. For example, aluminum chloride (AICI3), iron III chloride (FeC ^) and silicon tetrachloride

(SiCU) are formed.

The elemental carbon (C) obtained during the thermal decomposition of the chlorinated hydrocarbons reacts either with the fluidizing gas (CO2) or with the bound oxygen of the metal oxides to form carbon monoxide.

Reaction equation 3 describes the chlorination of silicon dioxide with the formation of silicon tetrachloride and carbon monoxide.

Si0 ₂ + C ₂ CI ₄ τi SiCI ₄ + 2 CO

Reaction equation 3

The following reaction equation generally applies to the disposal of PER with slate:

Si0 ₂ + 2 Al ₂ 0 ₃ + 2 Fe ₂ 0 ₃ + 7 C ₂ CI ₄ τ SiCI ₄ + 4 AICI3 + 4 FeCI ₃ + 14 CO

Reaction equation 4 It becomes clear from reaction equation 4 that various metal chlorides are formed in addition to carbon monoxide. All substances are initially gaseous at temperatures around 1000 ° C. Immediately after the reactor, the gases cool down very quickly to around 800 ° C through the ambient air.

Separation devices such as cyclones or activated carbon filters make it possible to separate and retain dust or crystalline metal chlorides, but mainly aluminum chloride and iron chloride, from the process gas stream. Supported by a blower, the gas flow is drawn through the filters. This has the consequence that a slight negative pressure already on Reactor outlet is to be noted, which is in the range of about 0.01-0.05 bar under normal pressure.

The residual gases contain gaseous silicon tetrachloride and carbon monoxide. Since the silicon tetrachloride changes to the solid state at temperatures below - 68 ° C, the process gas must be cooled down to temperatures of around - 50 ° C. This is done by pre-cooling with liquid nitrogen and post-cooling using a cooling mixture in a condensation column. The cold mixture used is an acetone / dry ice mixture, which can generate temperatures down to a maximum of - 86 ° C. The gaseous silicon tetrachloride is reflected in the above Temperatures in the condenser are low and is collected in a storage container. The degree of purity of the condensed silicon tetrachloride is approximately 96%. Any foreign substances that may be present can be removed by a subsequent fractional distillation. The result of the purification by distillation would be a silicon tetrachloride solution with a degree of purity of approx. 99%.

After the condensation, the process gas is fed to an alkaline gas wash with a 10% potassium hydroxide solution according to the countercurrent principle. The gas purified in this way only contains carbon monoxide.

Example of use 2: Disposal of vinyl chloride The process engineering design of the system corresponds to the design that was also used for the disposal of perchlorethylene (PER). The basic chemical reactions are described below.

When vinyl chloride (C ₂ H ₃ CI), as a monomer of polyvinyl chloride (PVC), is reacted with shale waste, the following chemical reactions take place: Si0 ₂ + 4 C ₂ H ₃ CI + 6 C0 ₂ → SiCI ₄ + 6 H ₂ + 14 CO

Reaction equation 5

Al ₂ 0 ₃ + 6 C ₂ H ₃ CI + 9 C0 ₂ ^ 2 AICI3 + 9 H ₂ + 21 CO

Reaction equation 6 Fe ₂ 0 ₃ + 6 CH ₃ CI + 9 C0 ₂ τ 2 FeCI ₃ + 9 H ₂ + 21 CO

Reaction equation 7

The result of the sum reaction equation is:

Si0 ₂ + Al ₂ 0 ₃ + Fe ₂ 0 ₃ + I6 C2H3CI + 24 C0 ₂ τ

SiCI ₄ + 2 AICI3 + 2 FeCI ₃ + 24 H ₂ + 56 CO

Reaction Equation 8

The process engineering separation of aluminum and iron chloride (AICI3, FeC ^) takes place on the one hand by centrifugal force separation in a cyclone and on the other hand by separation in special filters. The silicon tetrachloride is separated off in the manner already described.

It can be seen from reaction equation 8 that in addition to the metal chlorides, a synthesis gas consisting of carbon monoxide and hydrogen is formed. The ratio between hydrogen and carbon monoxide is 1: 2.3. One speaks here of a so-called synthesis gas, which has multiple technical uses.

Example of use 3: Disposal of hydrocarbon (KW) or halogenated hydrocarbon (HKW) waste in the presence of calcium oxide

The various feed materials, such as Oils, greases, PCBs, CFCs, solvents or the like are fed through a dosing device, e.g. an eccentric screw pump, conveyed into the reaction zone. There is a sudden thermal breakdown of the feed materials into short-chain hydrocarbons. The residence time of the feed materials or that of the cleavage products formed is determined by the height of the reaction zone.

As a rule, there is an almost quantitative splitting into essentially hydrogen and methane, the volume ratio hydrogen to methane being clearly on the hydrogen side. Since the melting point of calcium oxide (CaO) is around 2500 ° C, no large amounts of synthesized calcium compounds are to be expected. If, on the other hand, halogenated feed materials, in particular chlorinated materials, are reacted, then a reaction occurs between the calcium oxide and the halogen atoms of the feed materials.

Calcium chloride (CaCl) is essentially formed as the reaction product, which remains in the reactor as slag or melt. The following reaction equation (reaction equation 1) takes into account all essential products that are formed during the disposal or recycling of a halogenated hydrocarbon. The individual products were calculated thermodynamically and verified experimentally.

2 CaO + 4 C ₂ H ₅ CI - »2 CaCI ₂ + 2 CO + CH ₄ + 5 C + 8 H ₂

Reaction equation 9

In addition to this reaction, carbon is also discharged from the reactor in the form of fine soot particles.

The separation of the other gaseous components hydrogen and methane, or hydrogen and carbon monoxide (CO), is carried out by gravity separators, e.g. a high performance cyclone.

As a precaution, the gases cleaned in this way can still be passed through activated carbon filters. If there are still foreign components in the process gas, they can be removed either by targeted condensation or by gas scrubbing.

In the end, usually only one synthesis gas consisting of carbon monoxide, methane and hydrogen is left, which is suitable for versatile technical Applications, e.g. energy generation or use for chemical synthesis (methanol synthesis).

Claims

claims

1. A process for the disposal of halogenated and non-halogenated waste materials, characterized in that the waste materials are reacted with metal oxide-containing products with the exclusion of oxygen at temperatures of 800 ° C to 1100 ° C.

2. The method according to claim 1, characterized in that the waste materials contain carbon.

3. The method according to claim 1 or 2, characterized in that carbon dioxide is added in the method.

4. The method according to any one of the preceding claims, characterized in that carbon is added in the method

5. The method according to claim 4, characterized in that graphite and / or coal is used as carbon.

6. The method according to any one of the preceding claims, characterized in that halogenatable metal oxide-containing products are used as the metal oxide-containing starting material.

7. The method according to claim 6, characterized in that products are used as halogenatable metal oxide-containing materials, the Tiθ2, Siθ2,

Contain AI2O3 CaO and / or Fβ2θ3 or a mixture thereof.

8. The method according to any one of the preceding claims, characterized in that as halogenated waste materials, solvents such as: carbon tetrachloride, chloroform, methylene chloride, tetra- and trichlorethylene, tetrachloroethane, coolant or refrigerant, PCB, pesticides, fungicides and herbicides, halogenated plastics such as e.g. PVC, can be used.

9. The method according to any one of the preceding claims, characterized in that a proportion of the metal oxide which corresponds to the chlorine content of the waste materials is converted into metal chloride.

10.The method according to any one of claims 1 to 7, characterized in that waste oils, lubricants, greases, paints, paints, as non-halogenated waste materials, Tars, waxes, plastics, coolants and solvents, brake fluid or similar non-halogenated substances and materials are used.