DE2943273C2 - Use of bleaching earth containing oil, fat and / or waxy - Google Patents

Description

a) The use of waste bleaching earth whose calorific value is at least 4000 kj / kg, preferably in the range from 4000 to 25,000 kj / kg, in particular 6000 to 20,000 kj / kg, enables considerable energy savings in the firing stage;
b) a waste product polluting the environment is put to a meaningful use;

c) the high plasticity of the waste bleaching earth makes it possible to use the proportion of inexpensive leaning agents to increase the mixture to be deformed;

d) the lipophilization of the mass to be deformed results in better sliding behavior during molding, whereby a better texture of the moldings is achieved;

e) enables the good porosity of the ceramic products that can be achieved by the process according to the invention it is to reduce the proportion of expensive, common porosity agents considerably.

example

A typical clay raw material (brick clay containing kaoiinite and illite) was in increasing quantities Oily bleaching earth (specification see Table I) in a laboratory mixer (Lödige) and that required mixing water added The result was a pliable mass with good plastic behavior, from which sample bricks were formed.

After drying, shrinkage, surface appearance and flexural strength were determined Test bricks produced by the process according to the invention were slightly lighter than bricks without the addition of waste bleaching earth, adverse discolorations did not occur.

The firing took place in a test furnace whose firing process corresponds to that of a tunnel furnace (temperature = 1000 ° C; 10 hours heating up time and 8 hours holding time). There was smoke development during the burning to observe; however, there was no unpleasant smell.

The strength, shrinkage and water absorption data were determined on these bricks. notes to the Recipe, the test procedure and the determined. Table II shows the key figures.

Table I.

Properties of the oily fuller's earth

Appearance:

Loss on drying (110 °); Loss on ignition (1000 ° C / 10 '): Chemical Analysis:

Calorific value:

Loose, fine powder, brown, annealed: light beige

0.5%

40.0%

The main component is a highly plastic, swellable clay to which

oil or fat is bound adsorptively. SO3 content (soluble) <0.01%

160 k J / kg (= 2900 kcal / kg)

Table II

Properties of mass and cullet after the addition of 0,1,3 and 10% waste bleaching earth

additive
Wt%

Mixing water required)% by weight

Dry shrinkage ² )

Burning

shrinkage

1000 ° C / 8h ² )

Total shrinkage

Water intake des
Shard ³ )

Flexural strength
Relative values ⁴ )

raw,
separate

burned
1000 ⁰ C

37 43 43 44

9.2 8.8 8.8 8.0

4.1 5.0 5.0 6.0

17.7
19.4
20.7
23.6

1.0
1.1
1.0
1.0

1.0
1.8
1.3
4.2

according to Pfefferkorn determined with a Kröplin shrinkage measuring device according to DIN 51 056, para.

according to DIN 51 030; 0% 1.0

Claims (1)

Claim: Use of bleaching earth containing oil, fat and / or waxy to partially replace clay in the Manufacture of heavy clay products. The invention relates to the use of oil, fat and / or waxy bleaching earth in the production ίο heavy clay products. Ceramic products include fired, synthetic building materials, such as B. Bricks, clinker, stoneware, refractory building materials, etc., understood. The main component of these ceramic products is clay, which is mostly with non-plastic leaning agents, such as. B. sand, feldspar, phonolite, baked clay or clay, and with water, optionally with the addition of other customary additives, such as. B. fluxes, coloring agents etc, mixed, molded into molded articles, dried and fired. During the firing stage, a chemical reaction occurs between the silica and the clay of the clay which leads to the desired solidification and hardening of the mixture. But it is precisely this firing stage in view of increasing energy shortages, the stage that today is increasingly making the production process profitable certainly. The object of the invention is to provide a method for producing ceramic, in particular coarse ceramic To provide products that can be carried out with the usual existing equipment and this enables energy to be saved without impairing the valuable properties of the end product. The solution to this problem is achieved in that instead of some of the used in the mixing stage Clays oil, fat and / or waxy bleaching earth used. According to the invention, bleaching earth denotes finely crystalline and water-containing aluminum and / or Magnesium silicates from the montmorillonite group, which, depending on where they were found, are called fuller's earth, Florida earth, bentonite, etc. are in the trade. These bleaching earths are used because of their high adsorptive power Used for cleaning and bleaching mineral and vegetable oils, fats and waxes and the like. : io After their adsorption capacity has been exhausted, these are now bleaching earths containing oil, fat and / or wax (Waste bleaching earth) sent to a special landfill as worthless waste material and thus contribute to Pollution of the environment. While it is known in the art to use montmorillonites, i. H. the main component of the unused Add bleaching earth to the mixture to be burned in the manufacture of ceramic products. These additives can only be added in very small quantities, otherwise the mass to be processed || becomes too plastic, d. H. can no longer be processed with the usual equipment. Besides, these are ' Swelling capacity and the resulting high dryness shrinkage differ in such a way from those more usual ceramic raw materials that the dimensional stability of the products with higher additions of montmorulonite is no longer preserved. It has now been found that waste bleaching earths can replace part of the clay in the manufacture of ceramic products and, due to their oil, fat and / or wax content, lead to energy savings in the _li: firing stage. This effect is already noticeable at a content of at least 10% by weight of lipoid substance (based on dried fuller's earth) and naturally becomes more significant with an increasing proportion of lipoid substance. It is advantageous to use waste bleaching earths which contain 10 to 50, preferably 15 to 35% by weight (based on dried bleaching earth) of fat, oil and / or wax. It is advantageous to replace 1 to 25% by weight, preferably 1 to 15% by weight, of the clay, calculated on the dried state, with waste bleaching earth. Surprisingly, despite the massive lipophilization due to the addition of the waste bleaching earth, none Separation of the mass to be deformed, the need for water to produce the mixture only increases so insignificant. Above all, the dimensional stability of the green moldings and the end product is unchanged. In addition, it was by no means foreseeable that the total shrinkage of the deformed mass during firing, despite the content of oil, fat and / or wax, hardly differs from the total shrinkage of conventional masses and the process according to the invention can thus be carried out without problems with existing equipment.
The advantages of the method according to the invention include: