IL104083A - Ecologically harmless raw materials produced from liquid and solid waste useful as valuable material for building and construction products - Google Patents

Abstract

The invention relates to an ecologically sound disposable product, for example usable as a building material, obtained from wastes, and to a process for the production thereof. By means of specific additives, the process can be controlled in such a way that the end product has varying building material properties and that pollutants, which have been present in the starting material, are present in the end product either as harmless substances, which have been reacted further, or in a bound or immobilised form.

Description

IN i n-i ϊΐίηοοη ο*-ι.η·>ηη π:_>:ΐοί? tPpun OIPNKJ ub nnin Ecblogocally harmless raw materials produced from liquid and silid waste useful as valuable material for building and construction products Peter JENEY C. 88297 6 f) Ecologically harmless raw materials produced from liquid and solid waste useful as valuable material for building and construction products The invention concerns the transformation of toxic and nontoxic waste into ecologically harmless raw materials useful to make building materials and the process for its preparation .

From the professional literature many processes are known for the treatment and disposal of waste sludge, domestic, refuse and hazardous and industrial waste. Most of the processes used until now, however are burdened with more or less significant disadvantages for the environment.

For example, the use of sludge as fertilizer for agricultural purposes can lead to a partial sterility of animals due to its hormone content as well as its content of residues of drugs, pesticides, hydrocarbons, heavy metals etc.

The usual incineration of domestic refuse and waste results beside of ash also in harmful flue-gases which either escape to the environment or are adsorbed in a flue-gas cleaning plant. In the case of a flue-gas cleaning plant, however, again there occurs not easily disposable toxic residues.

Most of the known disposal processes are only partial solutions with the goal to reduce the amount of waste whereby, however, the contamination in the remaining residues usually increases to several times the original content.

Usually a reusable material may only be obtained by material specific collection as well as high energy costs (e.g. glass and aluminum recycling). The conversion of unsorted toxic and nontoxic waste into a reusable, ecologically harmless product without the generation of new, difficult to dispose of residues is therefore very much desired.

The present invention provides a solution for the reuse of waste by converting it into an ecologically harmless product useful e.g. as building material, which comprises 30-80 % by weight of organic material and can have a fire-retarding effect of more than 65 minutes (DIN 4102).

For the invented inert-like product from waste there exists a large variety of applications to use as either straight forward building material or laminated to other materials, for example in underground and surface engineering, in the construction of water and drainage pipes, in horticulture, and landscapes and in the construction of sports grounds, or as a variety of soil-improvement products.

Other products from converted waste may for example be used as filter and substrate materials in the construction of roads and sports grounds, as heat and sound insulations, and waterproof canal and drain insulations, bricks, drainage plates, building material for inner and outer walls, filling insulations, pouring plaster, fire retarding plates, outer and inner plastering, etc.

Despite the starting materials (waste) being highly contaminated, the inventive products of waste disposal are ecologically completely harmless, since organic or inorganic toxic products therein are either bound or have been transformed into a harmless form and heavy metals are almost entirely immobilized or recovered, so that less heavy metals are extracted from the inventive products by usual extraction methods (ELUAT-TEST-INERTSTOFFE according to TVA of December 10, 1990) than from usual building materials, made of "clean", raw materials.

The advantages of the inventive inert-like raw material from waste therefore are not only their properties due to their composition and structure, which make them valuable building materials for many applications, but also the ecologically harmless waste disposal . The inert-like new products of waste disposal also allow that such treated waste can be deposited in normal waste deposit sites after their treatment by the process, even if before treatment toxic elements were present, or may again be transformed into new building materials according to the process which is also object of the present invention .

As has already been mentioned, a further object of this invention is a process for the preparation of the inventive products using as raw material toxic and/or nontoxic solid and liquid waste.

As raw material a wide variety of different types of solid or liquid waste can be used. Usually sludge, flotation residues, domestic refuse, waste of packing material, contaminated soils, residues of industrial filters, rubber and tires, residual chemicals, animal manure and other agricultural waste is used, whereby the process is not restricted to these starting materials . The waste to be disposed of will be called in the schematics secondary raw materials.

To these waste materials additives are added during the production process. These additives are divided into two groups, the structural or base chemicals and the control reagents or primary materials.

As additives specific waste can also be used containing the required elements, so that the amount of pure chemicals or materials, respectively, may be significantly reduced, usually to about 7 % by weight, referred to the amount of secondary raw materials. By the reduction of chemical reagents to be purchased, the waste treatment process again becomes cheaper.

It is obvious that one can work exclusively with waste if sufficient amounts of chemical elements are contained in it.

Useful sources for reagents are, beside pure chemicals also wastes, for example anti-frost products (glycols), alcoholic by-products, waste of oils and oil derivatives; refinery waste (especially on the basis of urea and polyoles), waste of polyol-water-mixtures, e.g. from the production of paints, polyurethane waste, foam plastic waste, wastes of iso-cyanates, iron salts and ester compositions.

Halogenated hydrocarbons or their by-products, respectively, may also be used, e.g. fluoro-chloro-hydrocarbons as they are for example known under the trade name "Freon".

If halogenated materials are used (e.g. Freons, dioxins, PCB's etc.) they may be irradiated just before the reaction step I, for example with 137cs or preferably with 60QO. By the 'Jf-rays, emitted by these radioisotopes, the halogens are at least partially eliminated from the organic material. This superposed reaction may be favorable for the reaction of step I .

It is advantageous that waste to be treated is analyzed at its delivery and stored in different tanks and containers according to its analysis.

In this analysis (according to the TVA of December 10, 1991) further to the metals the organic part comprising hydrocarbons and possibly dioxins, formaldehyde and the like are also included. If the heavy metals contents are high, a pre-treatment of the waste for recovery of metals may be advantageous , e.g. by hydrometallurgy.

The processing of waste is preferably performed according to the process-layout as is presented in the figure, in which reference is made to: I material to be disposed of (waste, secondary raw materials ) II carrying and structural materials (base chemicals ) III regulating chemicals (primary materials) IV polyols A-E analytical tests I-7 connection lines of the aggregate in the process flow 8-10 return lines II-14 connection lines of the aggregate 15 reaction switch point 16-18 lines for transportation in process flow direction 19 return lines 20 transportation lines for further treatment (mechanical ) These optionally presorted materials (I) may then be transported to the corresponding place in the plant according to the desired final product to be made and the previous analysis and if necessary they may be shredded and/or crushed and mixed together. After the mixing of the secondary raw materials which are to be processed, these are transferred to a further mixing container in which the first base chemicals (II) as well as the isocyanate are added.

The isocyanate is a very important component since it reacts with undesired materials such as uric acid, ammonia, hormones (from sludge and waste water) as well as residues of organic and pharmaceutical substances, so that these compounds are then present in an incapsuled form or transformed into harmless compounds. Furthermore, these reaction products as well as the later formed reaction product between not yet reacted isocyanate and polyols are an important component of the desired plastic structure which is responsible for the excellent properties of the final product.

It is therefore necessary that isocyanates are present in the starting mixture in a total amount of up to 0.3 % by volume. Further materials which may or must, respectively, be added to the secondary raw material mixture prior to the first reaction step according to the analysis are: lime, cement, gypsum, bentonite, clay slate, slag of combustion plants, soil, sand and sludge of different kinds, straw, reed and bark, whereby the addition of lime, preferably a mixture of quicklime and unbaked lime, is necessary.

In a first reaction step (reaction step I) a mixture which comprises at least some of the above mentioned materials is reacted for at least 1 to 15 minutes at a pH of about 12 and at temperatures between 80 and 100°C and at a pressure of 50 to 150 bar. In this reaction step a solidified structure is formed, which shows crystalline parts (= prehygienisation or neutralization step) .

In the process steps following thereafter, the composition of the reaction mixture is corrected by a two-step addition of regulating chemicals .

In a first step as regulating chemicals III iron(II) and iron(III) salts, preferably oxides, and, if necessary, aluminium hydroxide, boric acid, sodium tetraborate, hydrochloric acid, acetic acid, alcohol, sodium hydroxide, cellulose, enzymes, sulfur (preferably refinery sulfur = contaminated impure elementary sulfur) , humic acid as well as aeration additives are added. In this step additional isocyanates may be dosed subsequently if needed. After these additives have been mixed with the product of the first reaction step, separate polyols (N) are added which react with fatty acids, vegetable and/or animal oils and/or mineral oils, hydrocarbons as well as isocyanates . Because of the exothermic reaction of the up to then unreacted isocyanates with the polyols, the temperature increases to about 100-150°C. Hereby a fiber-binding pre-struc-ture is formed. The main reaction II usually is performed at this temperature and at a pressure between 100 and 250 bar and a neutral pH value, whereby the highly viscous suspension is now transformed into a solid formed molded product and the liquid-part has been condensated into this solid product.

After this transformation the quality of the new inert-like material is checked in an analytical process .

Thereby a sample is opened structurally, i.e. reduced in size and pulverized. If this sample does not meet the requirements and set quality standards, then the whole product of the main reaction II is structurally opened and either transferred to the reaction improvement or to the reaction step I. If the result of the test is positive, then the product is transferred to the final structure giving-step.

In the final structure-giving process the desired solidified structure is achieved at elevated temperature (150 to 250°C) and elevated pressure (150 to 350 bar).

It has been found that the product occasionally has the desired properties already after the main reaction II. The final structure-giving step in these cases may be omitted.

Already during the reaction step I a hygienization starts, which is mostly complete after the reaction step II. For security reasons, however, after the final structure-giving step a subsequent reaction step III is' provided, in which the products are intermediately stored, using their remaining reaction temperature and at a slightly elevated pressure.

By the following final control it is decided, whether the products are transferred for further treatment or whether they must be reprocessed once more.

The ranges of the (total) amounts, with which the process usually is carried out, are as follows: Secondary raw materials cardboard, styropor, plastics 0 - 20 % by volume sludge (dry substance 25 %) 0 - 40 % by volume slag, filter dust, flue ashes 0 - 30 % by volume domestic refuse (household waste) 0 - 50 % by volume total at least 20 % by volume further waste materials at most 60 % by volume content of critical metals 1 - 50 g/kg organic portion about 30 - 95 % by volume Additives isocyanate 0.2 0.7 % by volume basic chemicals 2 10 % by volume regulating chemicals 0.2 1.1 % by volume polyols 2 7 % by volume Technologically, the process is laid out in a form so that each reaction step may be separately activated if needed (cf. Fig.). It has been found that a one-step process possibly requiring longer reaction times as well as adapted pressure and temperature conditions may also work to produce inert-like products. In the one step process often temperatures up to 350°C are achieved.

The multistage as well as the single-stage process have the advantage that in spite of high temperatures no annoying odours, e.g. of leaking ammonia may be detected.

By variation of the additives, the temperature and the pressure, the properties of the inventive building materials may furthermore be influenced to and optimized for their final application, e.g. the reduction of the pressure results in a stronger foaming of the structure and thus to an elastic product .

In the final products obtained by the process, the presence of heavy metals and toxic organic or inorganic materials, such as dioxins and formaldehyde, can only be detected by standard test procedures in amounts below the permitted limits, if detectable at all.

The following example shall further explain the process : Example of a production process for a fire-retarding plate Secondary raw materials; cardboard, styropor, plastics about 20 % by volume sludge (dry substance 25 %) about 30 % by volume slag, filter dust, flue ashes about 20 % by volume domestic waste about 20 % by volume Analysis of the secondary raw materials; metals (Cu,Pb,Hg,Ca,Fe, Zn,Mn,Cr,Ni ) 25 g/kg organic portion 75 - 80 % by volume Additives ; isocyanate about 0.3 % by volume basic chemicals - cement ) - CaO ) about 7.0 % by volume regulating chemicals - acid (to pH about 7) 0.5 - 0.8 % by volume - Fe(II) and Fe(III) 0.2 - 0.3 % by volume polyols 3 % by volume Pressure Temperature other Parameters [bar] [°C] e.g. curing time reaction step I 50-150 80-100 1.5 - 5 min . main reaction II 100-250 100-150 1.5 rain . final structure giving step 150-350 150-250 1.5 - 5 min subsequent reaction own remaining step III weight temperature 2.5 hours With the 2.5 hours of the subsequent curing time the security is obtained that the product is indeed inert-like and hygienically acceptable according to the "Merkblatt M7 " of the FRG Federal Law. It has been found that the parameters may vary in the mentioned range without the final product being negatively influenced!

Claims (12)

1. Product of the conversion of toxic and nontoxic waste into ecologically harmless inert-like material, e.g. useful as building material, characterized in that it comprises from 30 to 80 % by weight of organic material and has a resistance against fire of up to more than 65 minutes.

2. Product according to claim 1, characterized in that remaining contents of heavy metals are only present in quantities below permitted limits as can be analyzed according ELUAT-TESTS as per TVA of December 10, 1990.

3. Product according to claim 1 or 2, characterized in that it can be laminated with another product of waste disposal or with a product from normal industrial production.

4. Process for the production of the product from waste treatment according to claim 1 or 2, characterized in that the waste is mixed with isocyanates, lime, iron (II) and iron (III) salts, preferably oxides, as well as polyols or with materials containing them, which may optionally also be waste, and reacted at temperatures of up to 350 °C and at pressures of up to 350 bar.

5. Process according to claim 4, characterized in that furthermore structuring materials and regulating chemicals are added.

6. Process according to claim 4 or 5, characterized in that the reaction is performed subdividedly into the following reaction steps: a) the waste is mixed with isocyanates, lime and, if necessary, further structuring materials and reacted at temperatures between 80 and 100°C and pressures between 50 and 150 bar, then b) the product of step a) is mixed with Fe(II) and Fe(III) salts, preferably oxides, as well as with one or more further regulating chemicals if necessary, then polyols are added and the mixture is subjected to a pre-structure-forming step at temperatures of 100 to 150 °C and pressures of 100 to 250 bar and c) the pre-structured product of step b) is brought to its final consistency at temperatures between 150 and 250°C and pressures between 150 and 350 bar.

7. Process according to claim 5 or 6 , characterized in that the structuring materials are selected from the group consisting of cement, gypsum, bentonite, clay slate, slag of combustion plants, soil, sand, sludge of different kinds, straw, reed and bark.

8. Process according to any one of claims 5 to 7, characterized in that the regulating chemicals are selected from the group comprising aluminium hydroxide, boric acid, sodium tetraborate, hydrochloric acid, alcohol, acetic acid, sodium hydroxide, enzymes, cellulose, sulfur, humic acid, aeration additives and isocyanates .

9. Process according to any one of claims 4 to 8 characterized in that halogen, especially chlorine containing waste is subjected prior to the reaction step I to an irradiation by ^-rays/ preferably to an irradiation by G^Co.

10. Process according to any one of claims 4 to 9 , characterized in that the product is analyzed at least once during the procedure and that the product may be transferred back or forward to any one of the already or not yet passed steps .

11. Use of the product of waste treatment according to any one of claims 1 to 3 as building, construction and raw material .

12. Use according to claim 11 as filter and substrate material for the construction of roads and sports grounds, as heat and/or sound insulation and waterproof canal and drain insulation, bricks, drainage plates, building material for inner and outer walls, filling insulation, pouring plaster, fire-retarding plates, outer and inner plastering.