DE1210369B - Process for the production of synthetic cement quartzite - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

Number:
File number:
Registration date:
Display day:

C 04b

German class: 80 b - 8/06

1210369
B74226VIb / 80b
November 12, 1963
3rd February 1966

The invention relates to a method of manufacture of synthetic cement quartzite from rock quartzites or other strongly renewable quartz, quartz sands or quartz gravel, as a starting material for the production of refractory ramming mixes containing silica and mortars or stones. -

It is known that rock quartzites and the like, when burned to high temperatures, are converted into Crystal modifications high quartz, tridymite and cristobalite grow back strongly and therefore a considerable amount Increase in porosity and decrease in strength suffer. Because of this, they are quartzite Raw materials for the manufacture of refractory building materials are not as suitable as cement quartzite, which because of the In the presence of microscopic and X-ray amorphous crystallites, transform benign, i.e., during the transformation at high temperatures only moderately with little increase in porosity and decrease in strength grow back.

These differences are due to the different crystal sizes and the corresponding differences Distribution of the accessory components. If it is possible to influence a rock quartzite in such a way, that the size of its crystals is reduced and, in addition, X-ray amorphous crystallites, d. H. one So-called amorphous phase, formed, it should be possible to convert rock quartzites into a synthetic one Cement quartzite manufacture, which in its properties will be at least equal to, if not superior to, natural cement quartzites, since it can be found in the Hand has to control the proportion of amorphous phase and the distribution of accessory components.

The known world supply of cement quartzite is becoming depleted, while rock quartzites in large deposits are pending. It is therefore of great advantage if such a conversion succeeds.

Attempts have already been made to produce molding compounds for silica stones by adding quartzite and possibly Grind sand with milk of lime to the required grain size and mix. Even you may already have finely ground sand or quartzite with unslaked lime with the addition of Treated water at elevated temperature and optionally elevated pressure and this mixed product still mixed with crushed quartzite, optionally with the addition of water. The one from this Mixture shaped stones were then fired in a manner known per se, the quartz in tridymite is converted.

However, it has been found that this known method only partially converts the rock quartzite into Cement quartzite is converted.

Process for the production of synthetic
Cement quartzite

Applicant:

Höganäs-Billesholms Aktiebolag, Höganäs

(Sweden)

Representative:

Dipl.-Phys. Eilers, patent attorney,
Frankfurt / M.-W 13, Am Römerhof 35

Named as inventor:
Kjell Yngve Björklund, Höganäs;
Karl-Johan Leander, Hälsingborg (Sweden);
Dipl, -Ing. Rudolf Rasch, Frankfurt / M.

According to the invention, the strongly renewable quartzites are thereby converted into synthetic cement quartzite converted, that the quartzite broken into pieces and pre-fired in the temperature range from 575 to 1450 ° C in the autoclave above 165 ° C hydro- is treated thermally.

In an older invention, the proposal was made for the production of silica stones to grind the pre-fired rock quartzite, to mix it with lime, to shape it into stones and after the Pre-harden the shaping by means of a hydrothermal treatment and only then finally burn it.

According to the present invention, the rock quartzite broken into coarse pieces is obtained from the quarry first pre-fired in a kiln and then hydrothermally treated in an autoclave. In the autoclave the rock quartzite is converted into cement quartzite. The presence of milk of lime has how showed the effect of shortening the duration of treatment is basically not necessary.

The individual stages of the process according to the invention are explained in more detail below:

1. Pre-firing of the quartzite.

The rock quartzite is used to loosen the structure above 575 ° C, the temperature of the Low-high quartz conversion, pre-fired. It is possible to use the material as a piece material

■ -. ■ -; - - 609 503/368.

burn or as pre-broken grain. As a furnace, conventional furnaces of the ceramic industry, such as. B. ring, chamber and tunnel furnaces, as well as shaft furnaces, rotary kilns and modern kilns, such as sinter belt, fluidized bed furnaces, etc. The pre-burning can be carried out up to temperatures of 1450 ⁰ G, ie in the entire area in which a loosening of the Structure and a shattering of the crystallites by the thermal treatment takes place, but below the area in which the quartzites disintegrate due to excessive regrowth.

2. Hydrothermal treatment.

These quartzites, pretreated in this way, are hydrothermally treated in autoclaves at temperatures of more than 165 ° C. The most economical way to work is in the temperature range between 180 and 225 ^° C., at steam pressures ao between 10 and 20 atmospheres. The duration of the treatment allows you to vary the proportion of amorphous quartz (basal cement). As a rule, a treatment of over 100 atmospheric hours is required (pressure in atmospheres · time in hours). -,>

The presence of milk of lime (hydrated lime and water) lowers this value to about Atmosphere hours. If the proportion of basal cement is to be particularly high, you will also be in In the presence of milk of lime, increase the treatment to 100 or more atmospheric hours. -

The milk of lime can be combined with the quartzite in different ways. Either one soaks the thermally loosened quartzite in a vacuum treatment with the milk of lime or lets the thermally loosened quartzite saturate itself under pressure with milk of lime or brings it thermally loosened quartzite together with excess milk of lime in the autoclave.

The aforementioned values for the number of Atmospheric hours change in other temperature and pressure ranges.

The quartzitic raw materials prepared according to this process are known to be further processed, where it is often expedient for economic and technological reasons to pretreat them in this way Only use quartzite fine grain that has not been pretreated.

Claims (4)

Patent claims: 1. A process for producing synthetic cement quartzite from highly regenerative quartzites, in particular rock quartzite, characterized in that the broken into pieces and pre-fired in the temperature range 575-1450 ⁰ C quartzite JmÄutoklav is hydrothermally treated above 165 ° <. 3 2. The method according to claim 1, characterized in that that the quartzite is used together with milk of lime in the autoclave. 3. The method according to claim 1, characterized in that the quartzite prior to use in the '' The autoclave is soaked with milk of lime in a pressure chamber. . 4. The method according to claim 1, characterized in that the quartzite prior to use in the Autoclave is soaked in a vacuum with milk of lime. 5. The method according to claim 1 to 4, characterized in that the hydrothermal treatment takes place in the temperature range between 180 and 215 ° C. 6. The method according to claim 1 and 5, characterized in that the hydrothermal treatment is extended over at least 100 atmospheric hours. . · 7. The method according to claim 1 to 5, characterized in that the hydrothermal treatment is extended for at least 65 atmospheric hours. . 8 "Method according to claim 1 to 7, characterized characterized in that the quartzite is ground to a grain diameter of 3 mm before the pre-firing will. Considered publications:
German patent specification No. 582 446. 609 503/368 1.66 © Bundesdruckerei Berlin