DE10021792C2 - Process for the manufacture of solidified products for the building industry - Google Patents

Description

The present invention relates to a novel method for Manufacture of solidified products for the construction industry from sludge, from construction waste or one Mixing it with other mineral waste.

Mineral waste, such as B. rubble, slag from incinerators, metallurgical slag, foundry waste, waste from the glass industry and kerami industry, waste from the manufacture and processing of building materials also mineral waste from the industrial extraction of stones and primary raw materials mainly consist of silicates, aluminates, carbonates and other inorganic compounds. They can come in practically all grits ranges from several meters down to the range of a few micro meters, usually only contain small amounts of organic components, can be contaminated with pollutants and are usually based on the individual particles, hard materials.

In the FRG, well over a hundred million tons of this waste are generated annually. For many representatives of this group have sophisticated recycling and usage procedures but these processes are mostly based on narrowly defined framework conditions knotted, so that still large amounts of mineral waste in ponds or landfills. The resulting costs, possibly incurred environmental damage, the consumption of natural spaces and the loss of principally recyclable materials has led to research efforts in this sector of waste management. General goal of this  Efforts are being made to turn the mineral waste into recyclable "secondary raw materials or building materials "or at least by immobilization of initially available pollutants, the deposition conditions of the to improve the respective waste. All of these processes thus pursue both eco Nominal as well as ecological goals.

When processing mineral waste, the material is usually removed dry processes sorted according to contaminants, Fe-containing and NE-containing materials, possibly crushed and classified into different grain classes. Coarser grain classes in A range of a few mm to well over 60 mm can be used as additives in the Production of concrete or as a base layer material in deep and especially in Road construction can be used; Grain classes in the range between about 100 µm and about 2 mm, can as z. B. Substitute for natural sands can be used. The The finest grain size below 100 µm, especially below 50 µm grain diameter, is in usually a worthless waste that is dumped and in many cases even has to be converted into a form that can be deposited.

Mineral waste, e.g. B. from the Construction industry or waste incineration slag, after a dry Pre-processing wet processed. This leads u. a. to the desired effects, that z. B. caked together particles of different composition without additional formation of very fine particles can be deagglomerated, jagged Slag particles of low grain strength at their weak zones in smaller, firmer ones Grains are separated and that rough grain surfaces emerge by rubbing off standing ridges and edges are rounded.  

Another advantage of wet processing is that by using Water as a transport medium is classified more clearly than with dry screening process is possible. The secondary building material thus produced contains less undesirable fines than a dry-made secondary building material. In addition, the water creates buoyant substances that are always deals with impurities in the mineral material.

While the coarser fractions separate easily and in this way Allow to drain, the fine fraction contains <100 µm, the particle size distribution is characterized in that the majority of the particles smaller than 63 microns, in particular is smaller than 20 µm, still large amounts of water. This water content will further reduced by hydrocyclones and sewage towers. The water content is then however still so large that the sludge is still pumpable, but not puncture resistant not on landfill or the like orderly landfill is capable of being deposited. In addition, the transportability by truck or container of flowing sludge much worse than that of puncture-resistant sludge (cf. DE 196 53 328 A1).

This access requirement for depositing, i.e. H. the puncture resistance, could only through further cost-intensive processes, e.g. B. centrifuge or thermal Process can be achieved (see. DE 197 27 172 A1).

DE 42 06 900 A1 describes a method for processing sludge masses, for example harbor silt, where the sludge has a dry, water-storing solid granules, for example aerated concrete, are added, which absorbs the water from the mud, so that the resulting Mixture forms a "more or less lumpy mass", which is about conveying and Metering devices can be metered and processed. To increase the bulk density  this product continues with an additive, such as sand or Chalk filler, and then mix this by adding cement in transferred a solidifying building material. By the content of the pore granules such products are of low strength and not for any Suitable for building materials.

DE 31 13 651 A1 relates to a device for reprocessing residual concrete, under "residual concrete" a not yet hardened, by washing out Diluted concrete sludge obtained in concrete containers is understood. A appropriate vortex device in the bottom area of the device ensures that the concrete components do not settle and the mixture together with other Fresh water for the production of concrete reused in a concrete mixing plant can be.

It is therefore the task of finding a method by which the wet mechanical treatment of mineral sludge easily and inexpensively converted into marketable secondary building materials can.  

The solution to this problem is achieved with the in the main claims benen features and is promoted by the features of the subclaims.

Semi-technical tests have shown that such a finely divided sludge, which water contents of up to 100%, preferably up to 60 or 70% by mass, has, by adding 5-25 mass% cement, based on the solids content of the sludge, and if necessary with the addition of dry sand or grit as a supporting grain and possibly also with the addition of other mineral waste to concrete can solidify. Part of the cement can also be advantageously added by adding latent hydraulic binders such as fly ash, especially from the combustion of Replace brown coal or trass. These can be used in amounts of up to 45% by mass. preferably 5-20% by mass are added, with 2-10% by mass as starter Cement should be included in the mixture. Fly ash is preferably used which serves on the one hand as a filler and on the other hand as a binder.

Depending on the strength of the concrete produced, it can be used to manufacture concrete Molded parts or also to be poured into simple concrete slabs. The latter can also broken up and by previously described dry processing method the, possibly supplemented by wet methods, in coarse-grained, marketable secondary building materials to be converted.

The sludge used can be very fine for this consolidation to concrete have d. H. a particle size of less than 100 microns, the majority the particle is smaller than 63 µm and in particular less than 20 µm and a water content of up to 100, preferably 50-80 mass%, based on the solid to have content. The particles should be predominantly mineral in nature and  in particular from silicon dioxide, aluminum oxide, and silicates and aluminates from predominantly calcium, iron, magnesium exist. You can in more or less to a large extent also contain clays.

Examples of mineral wastes that are suitable for the process outlined above after wet mechanical processing are listed in the following table according to their classification in the European Waste Type Catalog (EWC):

The necessary water content is achieved through appropriate partial drainage more water-containing sludges, for example by hydrocyclone, by settling in appropriately sized sedimentation tanks or in sewage towers and given if adjusted by adding dry, granular material. Unless the material is so far drained that it is 25-30 necessary for the setting of the cement % By mass of water no longer contains a corresponding amount of water Lich be added again.

The cement required for agglomeration of the mineral particles is in one Amount of about 10 to 35% by mass based on the solids content of the sludge added. A cement with a grain size of less than 100 µm is used as the cement preferably less than 50 microns, and in particular less than 20 microns, used, known Cement types such as Portland cement, iron Portland cement, blast furnace cement, trass cement, alumina cement, etc. can be used.

However, a latent hydraulic binder such as stone is particularly preferred product made from coal or lignite fly ash and Portland cement clinker  used, which already has sufficient consolidation in smaller quantities of the mineral particles contained in the sludge.

The sands and other additives added as a support grain should meet the requirements requirements of DIN 42 26 "surcharge for concrete (part 1) - surcharge with dense Structure "so that it is broken out of the molded blocks again material obtained also complies with this standard.

In principle, such substances can be dry as well as the usual building sands Screening materials made from building rubble with the appropriate grain size, broken slag, in particular ash waste, old chippings from the treatment of grit, sand, re stands of municipal sewage treatment plants, used sandblasting material etc. added become. These wastes can also contain pollutants without the Concrete consolidation is adversely affected. In these cases, the concrete consolidation lead to a fixation of pollutants or reduce their availability. The landfill properties could be harmed by reducing the eluability mineral waste containing substances or, in individual cases, a final storage is only possible and can be approved.

Common cement setting accelerators or retarders, Swelling agents, dispersants, etc. are added.

As far as the aggregates and additives are not also waste trades whose recycling is desired, these products should be economic reasons, since the real object of the invention is the solidification of Mud affects not to be contained in too large an amount. Are aggregates  thereby in amounts of 5-50% by mass and additives in amounts of 0.1-10 % By mass makes sense.

The sludge is solidified by cement and other Auxiliary substances are stirred into the sludge or with appropriate mixing units, e.g. B. Plate mixer, mixed and the finished mixture either in large plates or in appropriate forms can solidify and optionally air-dried.

The solidified material is then, if necessary after coarse crushing tion, dry in appropriate rubble treatment plants, or possibly then also processed wet. It can also be used together with normal rubble processed, d. H. crushed, classified and in the usual way as Building aggregate for the production of mortar or concrete instead of the otherwise required ten sand or gravel can be used.

Insofar as a concrete can be produced with the method described above, the If the strength is B 25 or above, this concrete can also be used to manufacture tion of molded parts can be used. This can be L-stones, paving stones under different size and shape or other molded parts.

example

The following substances were examined for their use according to the invention.

• 1. Sludge from the wet processing of rubble. water content 70% by mass, particle size distribution (% by mass) 90% <63 µm, 50% <20 µm,
• 2. Portland cement, grain size <20 µm,
• 3. brown coal fly ash, grain size <10 µm,
• 4. Construction sand, grain size 2.0-0.01 mm,
• 5. wet ground slag, grain size 2.0-0.01 mm, water content 20% by mass.

The components were in the amounts given in the table in one Cement mixer 15 min. mixed, with the addition of water not necessary and then cast into 5 cm thick plates. In all trials, After a hardening of 3 days, perfect solid building boards are obtained.

table

Claims (6)

1. A process for the preparation of solidified products for the construction industry from sludge from construction waste or a mixture of sludge from construction waste and other mineral waste, characterized in that the sludge of the construction waste has been obtained from the wet crushing of building rubble and a particle size of less than 100 µm, the water content of the sludge of the construction waste or the mixture is reduced by centrifugation or sedimentation or by adding water or dry, granular, mineral components to a water content of less than 100 parts water, based on 100 parts solid, for the production of concrete usual additives and additives are added, 5-25 parts of cement, based on 100 parts of solid, are added, the mass is homogeneously mixed and solidified. 2. The method according to claim 1, characterized in that the solidified Product after subsequent crushing and classification according to grain sizes as a substitute for gravel or sand in the construction industry is used. 3. The method according to claim 1 or 2, characterized in that as Cement a fly ash-cement mixture with 20-80 parts Lignite ash and 80-20 parts of Portland cement is used. 4. The method according to claim 1 to 3, characterized in that the Aggregates in amounts of up to 50, preferably up to 20% by mass, and the additives in amounts of up to 10, preferably up to 5% by mass, be added.   5. The method according to claim 1 to 4, characterized in that the Water content of the sludge is adjusted to 30-70 mass%. 6. The method according to claim 1 to 5, characterized in that in the Mass of waste containing pollutants, especially heavy metals be bound.