CS251987B1 - A method of preparing high-flowing bentonite - Google Patents

Abstract

Dry bentonite or bentonite paste or bentonite suspension with water is treated at a temperature of 2 to 110 °C for 1 to 180 minutes with hydrochloric acid or sulfuric acid or nitric acid at an acid concentration in the mixture of 0.5 to 35 percent by weight. The obtained solid phase is washed with water. In the case of the preparation of acidic bentonites, it is dried, in the case of the preparation of neutral or weakly alkaline bentonites, it is mixed with 1 to 10% by weight of sodium carbonate and dried at a temperature of 15 to 120 °C. Highly swelling bentonite is used in chemistry, food industry, pharmacy, cosmetics, veterinary medicine, and in the production of thermal insulation materials.

Description

251987

The present invention relates to a process for the preparation of high-activity bentonite.

Bentonite, the component of which is mineral montmorillonite, is characterized by, among other things, the formation of stable bulk sediments in water. The improvement in swelling of the natural bentonites is achieved by natrification, i.e. by the addition of sodium carbonate. Higher swelling values are achieved by natrification using vibratory grinding and stabilization of pressure retention at 0 to 100 Pa or at temperatures of -70 to 0 ° C or relative humidity of 0.1% (MS AO No. 199 882).

A disadvantage of the high-flowing bentonites thus produced is that the product retains high swelling capacity only under these storage conditions.

The above drawbacks are substantially eliminated by the preparation of high-flowing bentonite by the action of the inorganic acids of the invention.

Accordingly, the present invention provides a process for the preparation of high swelling bentonite by the inorganic acid displacement of bentonite or bentonite or bentonite suspension with water at 2 to 110 ° C for 1 to 180 minutes with hydrochloric acid or with sulfuric acid or nitric acid, so that the resulting acid concentration of the mixture is 0.5 to 35% by weight, and the solid obtained is washed with water, mixed with 0 to 10% by weight. sodium carbonate and dried at 15 to 120 ° C.

Said method of preparing high-flowing bentonites has the advantage that the product has a high swelling capacity and high thixotropy, which is maintained for a long time even without special storage conditions. Another advantage is that the product may be acidic, neutral or weakly alkaline in the preparation of sodium carbonate. Example 1 152 g of bentonite (locality Jelšový Potok) with a content of 34.2% by weight. water is mixed with 348 g of water and mixed well with a propeller stirrer. The suspension is heated to 90 ° C and 400 g of 35 wt% hydrochloric acid preheated to 90 ° C are added. The mixture was allowed to react for 120 min at 90 ° C. After cooling and washing three times with 1 kg of water, the solid phase separated by filtration is dried at 105 ° C, milled to a grain size below 0.1 mm and swelling (Czechoslovakia Pharmacopoeia 3), II, Avicenum, Prague 1970 (CSL). -3): 2.0 g of ben-tonite is aspirated in small portions to 100 cm 3 of water in the metering cylinder so that the next portion is added only when the previous portion has dropped to the bottom. bentonite suspension in water is subtracted from the start of soaking. Bentonite swelled to a volume of 82 cm 3. Example 2 60 g of bentonite with a content of 5.5% w / w and 10.4% w / w. iron oxide is mixed with 1140 g of water and mixed well. The suspension is heated to 50 DEG C. and 74 g (96%) of sulfuric acid are added. The mixture was allowed to react for 5 min at 50 ° C. After cooling and washing three times with 1 kg of water, the filtration phase is separated off, mixed with 3 g of sodium carbonate, allowed to react for 10 minutes, dried at 30 DEG C. and milled to a pH below 0.1 mm. Swelling according to CSL-3bola was 48 cm 3. Example 3 3 kg bentonite (Hungarian human body) containing 14.7 wt. water is mixed in a stirrer with 3 120 g of water. To obtain the paste, 1060 g of 96% by weight sulfuric acid are added, and the mixture is left to react at 25 ° C for 40 minutes. Then the paste was diluted with 10 kg of water, decanted and washed twice with 10 kg of water. Sodium carbonate (216 g) was added to the washed paste, the mixture was stirred and dried at 80 ° C. The dried product is milled to a grain size of less than 0.1 millimeter. The swelling of CSL-3 was 75 cm 3. Example 4 1000 g of floated bentonite (locality Jelšový Potok) with a content of 14.2% by weight. the water is poured into 5 kg of 16% strength nitric acid preheated to 96 ° C. The mixture is allowed to react for 180 minutes at 96 ° C. It is then quenched by the addition of 5 kg of water and filtered. The paste obtained is washed three times with 5 kg of water each. 17 g of carbonate sodium is added to the final wash product, the mixture is stirred for 15 minutes, dried at 105 ° C, and the fineness of the grains is reduced to below 0.1 mm. The swelling of the sheet-3 was 87 cm 3. Example 5 120 g of bentonite (Hungarian human body) containing 14.7 wt. water is mixed with 2 kg of water and the suspension is heated to 96 ° C. To the suspension was added 3 kg of 35% hydrochloric acid preheated to 96 ° C. The mixture is not allowed to react for 15 minutes, cooled and washed twice with 2 kg of water. After washing, 6 g of sodium carbonate are added to the paste, the mixture is homogenized, dried at 60 ° C and ground to a fineness of less than 0.2 mm. The swelling of CSL-3 was 80 cm 3. Example 6

The procedure is as in Example 5 sec

Claims (1)

The difference is that 40% by weight phosphoric acid is used instead of 35% by weight of other hydrochloric acid]. The swelling of CSL-3 was 15 cm 3. 87 8 High-swelling bentonite has a wide use in chemistry, food, pharmacy, cosmetics, veterinary, thermal insulation materials. PREPARATION The process of preparing a high-swelling bentonite by inorganic acid treatment, characterized in that the bentonite or bentonite paste or bentonite suspension with water is treated at a temperature of 2 to 110 ° C for 1 to 180 minutes with hydrochloric acid or acid. with sulfuric acid or nitric acid at an acid concentration of 0.5 to 35% by weight, and the obtained phase is washed with water, mixed with 0 to 10% by weight. sodium carbonate and dried at 15 to 120 ° C.