CS199882B1 - Method of producing stabilized highly liquid-absorbing natrified bentonite - Google Patents

Description

It is an object of the present invention to provide a stabilized, highly swellable, natrified bentonite which allows the bentonite thus prepared to retain high swelling even during long storage.

Bentonite, a constituent of which is the mineral montmorillonite, is characterized, inter alia, by its swelling properties in contact with water. This property is highly desirable when used for special purposes, e.g. in food, pharmaceutical, veterinary and the like.

In order to increase the swelling, the bentonite is usually treated, titrated by the addition of a certain amount of NagCOy. After milling, the bentonite thus treated has swollen values in the range of 20 to 30 ml / 2g, as determined by CSL-3.

It is known to produce highly swellable natrified bentonite with a swelling value above 35 ml / 2g, in which the bentonite is first ground by disk mills, e.g. type Losche and additionally undergo 3 further disintegration on a vibratory mill. Another approach is based on natrified bentonite, which is dried in aerofontane driers with separation of clastic particles and ground on vibratory mills.

A disadvantage of the highly swellable bentonites produced in this way is that the bentonite produced does not retain high swelling but gradually loses it. The largest decrease in swelling is. for 24 hours after vibratory grinding and approximately 14 days after grinding, the swelling is close to that of the commonly produced species.

199 882

199 882

These drawbacks are overcome by the process for producing the stabilized high-swellable natrified bentonite of the present invention, which allows the material to be elaborated with a swelling capacity of up to 60 ml / 2g, while retaining this property indefinitely. Natriated bentonite having a moisture content of 4 to 20% by weight, preferably 6 to 12% by weight. The water is milled in a vibratory mill at temperatures from -60 ° C to + 80 ° C, preferably from 10 ° C to 40 ° C. The milled bentonite and the lamb are freed of moisture after grinding is completed. Preference is given to drying in a vacuum oven at a pressure of 0 to 100 Pa or a drying of a stream of dry air at temperatures from 0 ° C to +60 ° C. The same results are obtained by removing the milled bentonite on the vibratory mill in a freeze-dryer at temperatures from -70 ° C to C ° C. The moisture content of the material must fall below 1% by weight. water. This stabilizes the high swelling properties and does not lose the bentonite even after prolonged storage until its moisture content increases.

The examples given below illustrate the process according to the invention.

Example 1

100 kg of raw bentonite (locality Jelšový potok) with a moisture content of 22% by weight is homogenized with 4 kg of Na 2 CO 3 in a stirrer. The bentonite, which has been treated in this manner, is left to rest for approximately 200 hours, after which it is dried at a temperature of 120 ° C and crushed to a size below 3 mm. The output moisture is 10 wt. water.

EXAMPLE 2 g of bentonite, natrified according to example-1, is allowed to mill for 5 minutes in a vibratory laboratory mill. The bentonite thus milled, having a moisture content of 9.4% by weight. was kept in a sealed container, and after some time intervals a swelling sample was taken. The swelling assay was performed according to Ca. liekopiau - 3. The results are shown in Table 1.

Example 3 g natrifikovaného bentonite sub-topic of Example 1 for 5 minutes, milled in a vibration laboratory mill at a temperature of 22 DEG C., after which hneS after grinding bentonite order to desiccator over P ₂ 0 g, and the evacuated to a vacuum of approximately 2 Pa was allowed to bentonite in the desiccator 24 hours at 25 ° C. The resulting moisture was 0.76 wt. After the vacuum was removed, bentonite was left in the desiccator until swelling was determined at certain time intervals. The results are shown in Table 1.

Example 4 g of bentonite natrifikovaného then come to Example 1, and / naaýtenými maintaining the water vapor for 3 days (final moisture content 16.3%), then 5 minutes and on crushed in a laboratory impact mill and after grinding the dried bentonite aa desiccator over P ₂ O ₅ under a vacuum of approximately 2 Pa as in Example 3. The results of the swelling measurements after certain time intervals are given in Table 1.

b / dried over P 2 O 3 in a desiccator for 3 days (1.36% humidity), then held for 5 minutes in a laboratory vibrating mill, and after grinding, the bentonite was dried 5 more in an desiccator with no oxygen.

199 882 for phosphorus to about 2 Pa as in Example 3. The results of swelling measurements are shown in Table 1.

Example 5

In each case, 50 g of the bentonite natrified according to Example 1 was ground in a laboratory vibrating mill for 5 minutes by grinding the mill apparatus with which it was used. the bentonite came into contact, held at temperatures of -60 ° C and 5 ° C during grinding; 14 ° C; 25 ° C; 35 ° C; 50 [deg.] C .;

C; the swelling results after grinding at different temperatures are given in Table 2.

Example 6 g of bentonite natrifikovaného according to Example 1 for 5 minutes, ground in a laboratory impact mill, then dried under vacuum of about 10 Pa PGO ^x ^ ® ⁱⁿ water, urea, that is. always at temperatures: -70 ° C; 18 ° C; 10 ° C; 25 ° C; 40 [deg.] C .; 60 ° C for 24 hours. The swelling results for these drying temperatures are shown in Table 3.

Example 7

The ground bentonite prepared according to Example 3 and exposed to air humidity (at a relative air humidity of 0.54 and a temperature of 24 ° C) after 21 days of storage in an anhydrous medium. The swelling changes are shown in Table 4.

Example 8 g of the natrified bentonite of Example 1 was milled for 5 minutes in a laboratory vibrating mill, after which the material was placed in a fluidized-bed drying oven into which dried air was blown with an inlet relative humidity of 0.02 at 43 ° C + 2 ° C. 3 hours The material thus dried, having a moisture content of 1.12 wt. of water was stored in a hermetically sealed container for 180 days. The swelling determined on day 3 after drying was 63.2 ml / 2g bentonite and after 180 days of storage was 58.8 ml / 2g bentonite.

Example 9 g of the natrified bentonite according to example 1 was ground in a laboratory vibrating mill for 5 minutes, after which the material was placed in a laboratory lyophilizer, with an initial temperature of -50 ° C and a gradual temperature rise during Pounding to 37 ° C. Drying lasted 24 hours. The water content of the dried material was 0.27% by weight. and the swelling was 65 ml / 2g bentonite.

Highly swellable materials can be utilized for special purposes in pharmacy and cosmetics (preparation of highly consistent butter bases and pastes) and in all areas of prior art bentonite utilization where high thixotropy values are low at low solid phase content.

TabuTka 1

Lying time, example number days 2 3 4a 4b nepuči av ml / 2g 0 59.2 64.0 58.0 36.0 0.25 50.8 . 66.0 56.8 34.8 1 46.0 - 57.2 35.2 2 44.0 65.6 58.8 34.0 3 44.0 62.0 57.2 34.0 7 39.2 66.0 53.2 33.6 13 38.0 66.0 54.0 33.2

TabuTka 2

temperature -60 ° C 0 ° C +8 ° C +25 ° C +30 ° C + 50 ° C + 75 ° C swelling ml / 2g 64 64 62 60 58 54 44

Table 3

temperature -70 ° C 5 ° C +8 ° C +24 ° C + 40 ° C +40 ° C swelling ml / 2g 62 65 61 60 58 49

Table 4

snooze time, days 0 21 21.3 22 24 27 40 swelling ml / 2g 64 64.5 53.5 46.0 44.0 42.5 38 % h ₂ c 0.76 0.80 4.21 6.75 8.32 8.63 0.70

D Β B D K Ε I YOU FIND

Claims (1)

Process for the production of stabilized high-swellable natri-bentonite, characterized in that the natri-bentonite is vibrated with a moisture content of 4% to 20% by weight, preferably 6% to 12% by weight of water, wherein the milling is carried out at temperatures from -60 ° C to +80 ° C, preferably from 10 ° C to 40 ° C, after which the milled bentonite is lyophilized. or dried at temperatures ranging from -70 ° C to +60 ° C, to a total humidity ranging up to 1% by weight of water.