EP0693306B1 - Method for fabrication of secondary row materials from waste - Google Patents

Abstract

Process to recycle waste materials by bringing them directly, along with at least one additive material contg. a glass or ceramic forming combustible substance, into the flame of a burner operating with oxygen or a gas contg. a higher amt. of oxygen than air. A combustion gas and molten combustion particles are formed, which are transformed in subsequent cooling into a glass like and/or basalt like and/or ceramic like mass. The waste materials are mixed with the combustible substance to a mixt. of mixing ratio 20-40 to 40-80 wt.%, and the mixt. is burnt in the flames at 1250-1500 deg.C and ambient pressure.

Description

The invention relates to a method for recycling waste materials by introduction the waste materials together with at least one glass and / or ceramic Self-combustible additive containing substances directly into the flame one with technical oxygen or with a higher oxygen content than air having gas operated burner, wherein a combustion gas and Molten combustion particles are formed, which then cool down a glass-like and / or basalt-like and / or ceramic-like mass are transferred.

Landfills are becoming increasingly scarce and environmental regulations are becoming stricter always make the disposal of waste, especially industrial waste, more difficult more. The waste is usually burned or deposited in landfills. The valuable materials contained in the waste are irretrievably lost.

Especially the disposal of residues that arise from waste treatment is problematic. For example, when waste is incinerated Furnace slag and boiler dust as residues. Usually it is Waste incineration downstream of a flue gas cleaning system, in the further fixed Residues arise. Depending on the type of flue gas cleaning, this includes filter dust, Evaporation residues from flue gas scrubbing water or Flue gas cleaning residues. Airborne dust that is retained in filter systems must be disposed of safely due to the fact that they can be eluted.

In particular, the residues from hazardous waste incineration plants represent a significant disposal problem. A deposit of the residues on Above-ground landfills are becoming increasingly difficult or even illegal forbidden. Disposal in underground landfills or as backfill material in the Coal mining requires lengthy geological surveys and Approval process and is uneconomical and ecologically unsatisfactory.

There has been no lack of attempts to inert the residues mentioned Incinerate waste. For example, a glazing of these residues technology discussed recently. Filter dusts are said to be inert, eluate-resistant Glasses can be transferred. The disadvantage of this method is a high one Use of energy that continues to increase due to the necessary aggregates.

Various methods are known from glass production for glazing Transfer mixtures of substances into a glass matrix. The substance mixtures have to do this consist mainly of silicon oxide, calcium oxide and aluminum oxide.

For example, it is common in the manufacture of bulk glasses for Glass production necessary raw materials in an indirect way with fossil fuels melt the melting furnace. A transfer of this known Process on vitrification of waste materials is problematic, however, since doing so Large exhaust air flows occur that can contain dangerous pollutants. A effective removal of these pollutants is achieved by diluting the exhaust air flows complicated by combustion gases or very expensive.

In addition, no residue of Special waste incineration plants are processed because these residues hardly contain glass-forming substances.

From DE-OS 41 11 917 a method for recycling combustible residues contaminated with heavy metals by partial oxidation is known. As residues, e.g. B. sewage sludge, which are fed together with gypsum from flue gas desulfurization plants an oxygen burner. The substances used are partially oxidized under increased pressure, producing a raw gas rich in CO and H ₂ . The mineral components of the sewage sludge are transferred into a molten slag, which solidifies into granules after cooling in a water bath.

The object of the present invention is a method for recycling to provide waste materials with which the waste materials can be used for economic purposes Can be converted into a fully usable product.

This object is achieved in that the waste with self-combustible additive to an educt mixture with a Mixing ratio of waste to additive from 20 to 40 to 80 to 60 Mass percent are mixed, and the educt mixture in the flame Temperatures of 1250 to 1500 ° C and ambient pressure is completely burned.

The proposed procedure is for waste, for the limited or there are no recycling options, an unrestricted repatriation in opened the economic cycle.

The invention is based on the finding that a particularly effective implementation of the waste into a basalt-like product, in which the contained in the waste Pollutants are safely trapped when the waste is in a certain mixing ratio together with glass-forming substances directly into the flame of a burner, especially one for the combustion of Solids provided solid burner and are introduced Ambient pressure can be completely oxidized. Because the glass-forming reactions are direct take place in the flame, compared to traditionally direct or indirectly heated melting furnaces achieved much higher sales.

This is done by using technical oxygen or one with oxygen enriched gas, especially oxygen enriched air, compliance the required high temperatures.

The technical oxygen is expediently in an air separator or Pressure swing adsorption system (PSA system) manufactured.

Due to pronounced turbulence in and around the flame such substances that are not incorporated into the melt can do so much better be separated as is possible with directly or indirectly heated melting furnaces would. By the extensive achieved with the inventive method Separation of these non-glass-forming substances, in particular anions such as fluoride, chloride and sulfate as well as volatile metals such as cadmium, zinc and Mercury, a very high product purity of the glass is made possible. The excellent product quality achieved means that Utilization options significantly improved.

The use of technical oxygen or a higher oxygen content than Air-containing gas or gas mixture also minimizes the resulting Exhaust gas quantity, which significantly reduces the exhaust gas purification system and thus becomes more economical.

The combination of technical oxygen with the solid fuel burner also enables the use of low-energy additives for automatic melting in the Flame without additional fuel.

The preferred waste materials are heavy metal contaminated, not leach-resistant, where appropriate, organically contaminated residues from waste treatment plants are used.

Such substances should be used as additives that are independent are flammable and ensure the desired product properties. Here In particular, substances come into question, the silicon and aluminum compounds contain. Low calorific value waste and / or residues with glass and / or are particularly advantageous ceramic-forming ash content.

Dry sewage sludge, which is disposed of anyway, is particularly suitable for this have to. The energy required for melting the waste can can only be obtained from sewage sludge incineration. An additional Another fuel is supplied to the burner after the start-up phase energetically not required. The sewage sludge contains glass-forming substances sufficient amount to also look at residues Hazardous waste incineration plants that contain little glass-forming substances to be able to manufacture glass-like product with high quality. Additional emissions are avoided when using sewage sludge as additives, because the Sewage sludge must be incinerated anyway in the future for disposal.

Another possibility is to add dry pyrolysis residues as additives use. Pyrolysis residues have a calorific value that for a conventional one Combustion is too low, but this is too low for the melting process according to the invention Use of the one operated with technical oxygen or with oxygen enriched gas operated burner is completely sufficient. Also included Pyrolysis residues enough glass-forming substances, so that from the disposal waste an unrestrictedly usable glass-like product can be manufactured.

Incompletely burnt out lignite ashes can also be used as additives be used. Lignite ashes are in terms of calorific value and content comparable to pyrolysis residues in glass-forming substances.

According to a further variant of the method according to the invention, the Rust diarrhea from domestic waste incineration plants or finely crushed Shredder waste can be used as an additive.

A further development of the inventive idea provides, in addition to the glass-forming and / or additive containing ceramic-forming substances at least one additional aggregate, especially asbestos waste, into the flame of the burner to introduce, which improves the quality of the vitreous melt. The share of this Additive to the educt mixture should preferably not 10 percent by mass exceed.

The educt mixture is expediently in a rotary tube furnace in the flame of the Brenner burned completely. As a result, long dwell times are incurred Exhaust gases and the resulting melt guaranteed. The rotary kiln is preferably formed with a small cross section and a large axial length, so a sufficient retention time for the waste and additives is achieved. The melted reaction products are deposited on the furnace wall. The substances that are not incorporated into the glassy melt, accumulate in the exhaust gas and are via a flue gas treatment device, which is preferably essentially from a quench, a hot gas dust separation and a harmful gas separation exists, deducted. The resulting melt is preferably in the liquid Condition discharged through a discharge opening of the rotary kiln.

Instead of a rotary kiln, a rotary drum oven or, preferably, a standing cyclone are used.

The waste and additives are expediently blown in using a Gas introduced into the flame of the burner. Low nitrogen is preferred Gases used, which prevents excessive nitrogen oxide formation. It can also a fuel gas, especially natural gas, propane or butane can be used.

According to a further development of the inventive concept, contaminated gas is e.g. out Landfills or polluted exhaust air e.g. from tank systems for blowing in Waste and additives used in the flame. Such gases have to to be disposed of so that two can be treated simultaneously with the waste Disposal problems or when using materials to be disposed of as Additives such as Sewage sludge or pyrolysis residues, even three Disposal problems can be solved at the same time.

To blow the waste and additives into the flame of the burner preferably uses a dispersing and metering device.

The method according to the invention is suitable for the treatment of all conceivable Waste, especially from industrial waste and especially from residues Waste incineration plants. The procedure for the treatment of is very special Residues from hazardous waste incineration plants are suitable. Such residues, e.g. Filter dusts from the flue gas cleaning of the special waste system show high Pollutant concentrations on and can with conventional glazing can only be treated with increased effort. The filter dust contains hardly any glass-forming substances. With the method according to the invention, straight such residues can also be recovered in an economical manner.

There are a number of advantages associated with the proposed method. By the use of technical oxygen or oxygen-enriched gas the amount of exhaust gas is significantly reduced, making the exhaust gas purification system is significantly reduced. In addition, there is no after the start-up phase Feeding another fuel in addition to the additives energetically required. Additional emissions are prevented, because they are preferred Additives are used that have to be disposed of anyway. Since the glass-forming reactions taking place directly in the flame are compared conventional furnace heating achieved significantly higher sales rates. By The use of a simple, less fault-prone system technology also Investment costs kept low. Selection and quality of the resulting glassy Products can be easily made by varying the quantity ratio of Wastes and additives and a suitable choice of these additives and optionally other additives can be determined.

The invention will be explained in more detail below using an exemplary embodiment:
Airborne dusts retained in filter systems of a special waste incineration plant, which contain pollutants such as mobilizable heavy metals, easily soluble neutral salts and organic pollutants, such as dioxins, furans, are fed to a rotary kiln. The rotary kiln has a ratio of axial length to diameter of at least 5 (L / D ≥ 5). A solid fuel burner for technical oxygen is used in the rotary kiln. For example, an air separator or a PSA system can be provided for the oxygen supply.

The dusts are removed from the rotary kiln with rotten, dry Sewage sludge from an industrial sewage plant is mixed intensively. The resulting The mixture of substances is created by means of exhaust air contaminated with pollutants in a pendulum gas device of a nearby tank farm for liquid hazardous waste, with one Flow rate of 9 m / s into the flame of the solid fuel burner using a Blown in the dispersing device. Due to the high prevailing in the flame Temperatures of over 1300 ° C set in the filter dust Substances and the glass-forming substances present in the sewage sludge, in particular Silicon oxide, calcium oxide and aluminum oxide, with high reaction speed around, whereby the filter dust is integrated into a glass-like matrix. This creates a basalt-like product, in which the pollutants are trapped in a safe manner are.

The feed materials are mixed with the gas flow in the rotary kiln entrained, react on the path running axially to the rotary kiln and the melted products are finally deposited on the furnace wall. The thus formed melt is continuously via a discharge opening of the Rotary kiln carried out. Depending on the intended use of the basalt-like product can be different Connect the melt treatment process (e.g. defined cooling in predetermined time units and / or mechanical processing).

• Anionen wie Fluorid, Chlorid und Sulfat sowie flüchtige Metalle wie Cadmium, Zink und Quecksilber werden über das Abgas ausgetragen.
• Die zur Glasbildung befähigten Stoffe werden im flüssigen Zustand abgezogen.

The implementation of the relatively small particles enables a significantly improved mass and heat exchange compared to the previous processes. On the one hand, this means that the formation of basalt-like structures is significantly improved. On the other hand, this procedure enables a better separation into the melted and gaseous phase:

• Anions such as fluoride, chloride and sulfate as well as volatile metals such as cadmium, zinc and mercury are discharged through the exhaust gas.
• The substances capable of forming glass are removed in the liquid state.

It is particularly worth mentioning in this connection that the described Advantages that energy and material sales are improved.

The flue gas cleaning essentially consists of a quench, a hot gas dust separator, a gas washer, a fixed bed adsorber and a blower.

The glass-like products produced in the process are in the street and Road construction, for recultivation purposes, as aggregates in the concrete industry and brick manufacturing industry, as inert mining supplies or as Thermal insulation can be used.

Claims (7)

1. Process for recycling waste materials by introducing the waste materials, together with at least one additive which is combustible in a self-sustaining manner and contains glass- and/or ceramic-forming substances, directly into the flame of a burner operated with technical-grade oxygen or with a gas having a higher oxygen content than air, forming a combustion gas and molten combustion particles which are then converted by cooling into a glass-like and/or basalt-like and/or ceramic-like composition, characterized in that the waste materials are mixed with the additive which is combustible in a self-sustaining manner to form a starting material mixture at a mixing ratio of waste materials to additive of from 20 to 40 to from 80 to 60 per cent by mass, and the starting material mixture is completely burnt in the flame at temperatures of from 1250 to 1500°C and ambient pressure.
2. Process according to Claim 1, characterized in that, as waste materials, use is made of waste treatment plant residues which are laden with heavy metals, not resistant to leaching, or may be organically polluted.
3. Process according to Claim 1 or 2, characterized in that, as additive which is combustible in a self-sustaining manner, use is made of a waste material or residue which has a low heating value and has a glass- and/or ceramic-forming ash fraction, in particular dry sewage sludge and/or dry pyrolysis residue and/or incompletely burnt brown coal ash and/or finely comminuted shredder waste.
4. Process according to one of Claims 1 to 3, characterized in that at least one further flux, in particular asbestos waste, which improves the quality of the glass-like and/or ceramic-like composition, is admixed to the starting material mixture, preferably in an amount of up to 10 per cent by mass.
5. Process according to one of Claims 1 to 4, characterized in that the starting material mixture is completely burnt in a rotary tubular kiln.
6. Process according to one of Claims 1 to 5, characterized in that the starting material mixture is introduced into the burner flame by a low-nitrogen gas.
7. Process according to one of Claims 1 to 6, characterized in that the starting material mixture is introduced into the burner flame by a gas which is to be disposed of.