DE4108031A1 - Prodn. of floatable materials for absorption beds - by carbonising pre-expanded grain, esp. useful in anaerobic waste water treatment plants - Google Patents

Abstract

Prodn. is effected by carbonising pre-expanded natural 'fruits' (esp. grains) at 180-450 deg.C. The starting material is popcorn, puffed wheat or puffed rice. Carbonisation is effected in the presence of air, opt. in a closed vessel to form a moulded prod. USE - The floatable materials are esp. useful as biomass carriers in biological (esp. anaerobic) waste-water treatment plants. They may also be used as packing materials in columns, trickle units and adsorption or absorption beds, as biofilter materials, as hydroponic culture substrates, as insulating materials, as fillers for plastics, foams, bricks and concrete, and as carriers for catalysts and 'active agents'

Description

The present invention relates to manufacture floating filler in a carbonization process and their use for various purposes.

To the performance of biological wastewater treatment plants, especially anaerobic plants, can be added to this floatable packing, on which the biomass can settle, then no longer discharged with the overflow of the sewage treatment plants becomes. For this purpose, e.g. B. porous packing with floating assets used, e.g. B. porous glass, synthetic Foams, expanded stone or organic masses, such as Corn cobs, wood chips, activated carbon pellets or coke from various types of coal.

Such packing should be as inexpensive as possible little biodegradable, of some degree same size and easy to handle technically. in the  general are from the usual packing for this purpose not all of these conditions are the same moderately fulfilled, so that wishes are still open here.

It has now been found that the packing of the desired species with only slightly different sizes can be made very easily by looking at expanded natural, possibly classified Fruits, preferably those with a high carbohydrate content some, such as advanced grains or nuts, in particular Cereal grains, at 180-450 ° C, especially at 200- 350 ° C charred. This treatment can preferably un ter air access, but also under exclusion of air or at throttled air supply. Ver smoldering reactions, which are the basic material of the driven fruits, but not their shape and size change significantly. The fillers available in this way no longer swell or only a little, they solve no longer stand up and become very slow or even not biodegraded when in aqueous medium be applied.

The floatable fillings available with a predetermined by the pre-expansion of the source crops Shape and distribution of the grain size can not only used in sewage treatment plants, but also everywhere where inexpensive, less swellable, insoluble parts fillings with relatively even particle size distribution be requested, for example in columns, Rieselan layers, biofilter layers, hydroponic systems, waste and Adsorption beds or also in the production of  insulating building materials and lightweight synthetic resin molding len, as a filling for foams, especially as a filling in polyurethane foams, during production of insulation fillings, of porous bricks or Concrete or from supports for catalysts or active fabrics.

Pre-expanded natural fruits are e.g. B. those who through a heat treatment known per se and / or water vapor, through natural processes or in As part of the heating process according to the invention Structure of an open, closed or mixed pore Expansion body with preferably spherical, egg-shaped or have approximately ellipsoidal shape, which in individual cases also be changed by bursting open can. Such advanced fruits are e.g. B. as Puffed corn, popcorn, puffed wheat or puffed rice are known. For in principle, the present invention all come fruits suitable for the formation of "puffed" fruits considered, e.g. B. cereal grains, legumes, nuts and other fruits. Is particularly well suited Popcorn, especially those types that are used in Expansion process the spherical shape of the Maintaining raw material. Puffed corn (popcorn) and puffed rice are preferred and / or puffed wheat used.

The carbonization of the pre-expanded fruits can also be taken under Inert gas (e.g. nitrogen or carbon dioxide) or water vapor. The disappearance times can range from a few minutes to 6 or more hours  be. It is advantageous if there is access to air and Single temperatures above 200 ° C expanded grain relatively evenly the respective ver temperature reached. That means: between Outside and inside area (surface and center) of the single fruit to be smoldered is preferably a Temperature difference of 50 ° C not exceeded. This can be achieved by looking at the smoldering after one Carries out temperature program for the maintenance of a as little as possible compared to the starting material shrunk end shape of the packing.

The method according to the invention can also be carried out directly or gradually heating to the selected maximum temperature.

The smoldering can e.g. B. in a rotary tube, on tab letts or rusting, in a fluidized bed or in heating gas flowed through fill, possibly directly in the Connection to the pre-expansion. Also one Heating a bulk of pre-expanded fruit in an open or closed vessel, heating by oil or other heating baths, by microwaves, AC currents or radiation, e.g. B. infrared radiation, is possible.

With slow heating with access to air and with removal the smoldering gases bake the smoldering particles in the general not or very little, making them easy classified or handled as such. Ver  baked smoldering approaches can be carefully mechanical crushing easily back into the individual Particles are separated.

You can pre-expand fruit before or after ver impregnation process with active ingredients or be layers, e.g. B. with acid donors, alkalization agents, catalysts (or their precursors), biolo preparations (e.g. of bacteria), biocides, quaternary, cationic or anionic coating tions, metal oxides (or their precursors), colors substances, odorants, ion exchangers, fertilizers agents, lacquers, hardening synthetic resin formulations (e.g. UP resins, epoxy resins, foamed or solid Polyurethane resins or formaldehyde resins), surfactants or Water repellents.

If you start by setting fruits that have not yet been expanded, about popcorn maize, in which between 180 and 450 ° C ablau initiate the smoldering process and leads it into ge closed but gas-permeable forms, so you get porous moldings from carbonization products, the use as such or in the crushed state can find z. B. in sewage treatment plants or as insulation or packaging material.

The following examples illustrate the preparation of the floatable packing according to the invention, for example arrested. The parts and percentages given refer to on weight unless otherwise stated.

Examples example 1

Commercial puffed rice (i.e., pre-expanded rice grains) with a bulk density of 100 g / l were in in a convection oven heated to 180 ° C for 30 min, then 30 min at 210 ° C and finally 3 h at 260 ° C.

After cooling there was a loosely connected, ver smoldered mass before, made up of single black puff rice grains and by slight mechanical loading movement was broken down into these. The bulk weight was 110 g / l. The easy-to-handle material was called Zu impact material in the manufacture of lightweight molded parts made of epoxy resin and PU foam.

Example 2

Commercially available puffed corn (popcorn) with a bulk density of 119 g / l, which consists of rounded, not burst particles existed and under the Be drawing Presco Corn was available in one Convection oven heated to 200 ° C on a rack for 6 hours. The oven had a ventilation pipe and one additional air access.

After cooling, there was a loose mass of charred, not caked spherical particles that are good was pourable. Had the original bulk weight does not change noticeably.  

The particles thus obtained were at 20 ° C for 100 hours stored in water for a long time. They swam on the Water surface and did not swell noticeably. After Water storage and then drying at 200 ° C the loss of soluble material contributed less than 0.8%. The structure of the pre-expanded seed grain fully preserved. They were, like the particles of the following example, as porous Floating bodies used in sewage treatment plants.

Example 3

The material obtained according to Example 2 was 3 hours heated to 300 ° C. There was a weight loss of 19% one, the particle shape was preserved. At a Water storage as in Example 2 was a weight ratio desire of less than 0.5%. The Schüttge weight was 109 g / l.

Example 4

The starting material also used in Example 2 was in a convection oven on a grate for an hour held at 150 ° C for a long time, then at 200 for one hour each 250 and 300 ° C.

After cooling, the material had a bulk density of 107 g / l. It consisted of very weakly together adhering, easily separable single grains with approx the original shape and structure.  

In contrast to that according to Examples 2 and 3 he particles held after this temperature program obtained grains a much fissured Surface. They are therefore even better than Floating bodies for sewage treatment plants, catalyst carriers and Column fillings.

Example 5

Commercially available, not yet advanced popcorn was in a steel basket in an oven preheated to 220 ° C air oven inserted and left in for 6 hours. You got a pile of foamed, burst and carbonized popcorn particles that partially coexist were hooked. The bulk density was 81 g / l. This material was annealed at 300 ° C for 1 h is then suitable as a catalyst carrier and as a Rie Sel body with a large surface.

In this case the pre-expansion was with the invention according to the smoldering process.

Example 6

The procedure was as in Example 5, but instead of the steel basket, a 60% by volume cube shape made of sheet steel was used, which was not filled with pop corn. A cubic shaped body of porous carbonization product was obtained. This can be used for isolation purposes. It had a density of 100 kg / m ³ .

Example 7

• a) 100 parts of the puff also used in Example 2 Corn was mixed with 40 parts of a 30% aqueous solution Solution of sec. Swollen ammonium phosphate and then dried at 150 ° C. Then 1 h at 200 ° C and 1 h at 250 ° C, where a Air-entry oven was used.

After cooling, spherical, loose lay together hanging porous particles in front with a bulk weight of 115 g / l.

• b) The same process was done with a 30% solution of acidic aluminum phosphate (instead of the sec. Ammonium phosphate) and a comparison received cash result.

The spherical particles obtained according to a) and b) were used as a carrier material in biofilters. They are also suitable as high-temperature insulation material fill.

Claims (6)

1. A process for the production of buoyant fillers, characterized in that pre-expanded natural fruits at temperatures between 180 and 450 ° C. 2. The method according to claim 1, characterized in that that as pre-expanded fruits puffed corn, puff wheat and / or puffed rice. 3. The method according to claims 1 and 2, characterized records that one with the smoldering above 200 ° C. between the surface and the center of an one fruit does not have a temperature difference of 50 ° C exceeds. 4. The method according to claims 1 to 3, characterized records that the smoldering under air occurs performs. 5. The method according to claims 1 to 4, characterized records that the smoldering in closed Performs shapes and thus receives molded parts. 6. Use of obtained according to claims 1 to 3 Packings in biological sewage plants, for colon nen, trickle systems, biofilter layers, ad and Ab sorption fillings, hydroponic plants, Isola tion fillings, for insulating building materials, for Manufacture of lightweight molded resin parts, as fill development for foams, for porous bricks and concrete and as a carrier for catalysts and active substances.