CS270828B1 - Method of bentonite's continuous countercurrent activation - Google Patents

Abstract

This invention applies to a method of bentonite activation using mineral acids. It is based on a suspense of bentonite in which there is in minimum 70% parts smaller than 200 μm, which is continuously antiflow-extracted by hydrochloric acid and/or sulphuric acid in the presence of salts of extracted metals arising on different levels of the extraction process up to the extraction of 65 mass % in maximum from the original content of metals in the bentonite, achieving a specific surface of 150 m<2>/g minimum, and a volume of pores smaller than 1.4 x 10<-8>m and not less however than 0.1 m<1>/g while the salt itself enters into the last extraction level.<IMAGE>

Description

The invention relates to a process for the continuous activation of bentonite with mineral acids. Starting from a bentonite auspension in which it is min. 70% of particles smaller than 200 µm, which are continuously countercurrently extracted with hydrochloric acid and / or sulfuric acid in the presence of the extracted metal salts formed at each stage of the extraction process, until the max. 65% by weight of the flood metal content in bentonite and reaching a specific surface area of at least 150 m / д and a pore volume of less than 1.4.10 m of at least 0.1 ml / g, with acid alone entering the noon extraction stage.

Porous silicate materials find wide application in sorption, vapor and liquid vaporization and catalytic hydrocarbon transformations. These properties are determined by the character of the matrix as well as the structure of the comparisons which are bounded by the matrix. Such materials include layered natural hydroslicates, clays whose basic structural building units are the layers of silicon tetraethers and aluminum octahedrers. Structural units of minerals from the group of montmorillonites, mica, ileites and vermiculites of the eu, consisting of court layers of silicon tetraethers and an interlayer of octahedrons of aluminum. The isomorphic inclusion of central atoms in octahedrons and tetrahedrons by other atoms is the cause of the wide variability in the properties and behavior of these clays.

The sorption capacity of these minerals ea will be increased by chemical treatment with acids at elevated temperatures resp. pressures, selectively extracting a portion of the matrix structure to provide materials with increased specific surface area with catalytically active acid centers and an increased micropore volume of 80 ·

Depending on the type and proportion of acid, temperature and extraction time e and the acid-activated bentonites produce different sorptive capacity and catalytic activity. The activation of bentonite ea itself takes place in the Sarza-like activators with vigorous stirring and suspension. In the presence of acid, a portion of the bentonite matrix is extracted, whereby the salts of the extracted metals and excess acid ea are separated from the solid phase by decantation and / or filtration, the product is washed with water, dried, ground and graded. *

USSR patent no. 63-544 discloses batch production of activated bentonite, where, after separation of the mother liquor e, additional additive extraction is performed with 15-30% hydrochloric acid. USSR patent no. 882927 discloses that the above-mentioned USSR patent δ. 638544 is not economical and recommends the activation of lump bentonite in rectification columns with partial use of mother liquors.

Said known spoeobml of batch activation in a relatively elevated mother liquor concentrate at the end of activation, i. salts of the extracted metals in admixture with unreacted acid, ea decreases the adorption capacity of the activated bentonite matrix.

In the case of US Pat. 638544 and no. 882927, the activation of bentonite is carried out in a volatile and uneconomical manner with a redistilled extender, the extraction rate e is greatly reduced by the coarse-grained extracted material and by its solid deposition disadvantageous for diffusion. Of these, the USSR Patents Nos. Nos. 6,844 and 882,927 do not provide an assumption of industrial use.

We have now goldened and developed a new, progressive, industrially exploitable epoch of continuous and countercurrent activation effected sequentially in two to four stages, with a fine-grained bentonite suspension entering into the first stage and a stream of concentrated solution of extracted metal salts and residual acid entering the first stage. solution of the acid and the suspension of the extracted bentonite which separates, washed with water, dried, grinded and eventually faded in subsequent operations. At the same time, in the intermediate stages of countercurrent extraction of bentonite with acidic acid, hydrodynamic aeparation, preferably in hydrocyclones, continuously separates the solid particles from the solution of the extracted metal salt and the extractant, which

CS 270 828 81 flows into the previous extraction stage and suspension and about 30% solids content to the next stage.

The object of the invention is a continuous countercurrent activation of bentonite by acids characterized in that it is successive in two to four stages from the bentonite matrix entering the first stage in the form of a suspension containing 150 to 500 g / l of dry matter, in which min. 70% of the particles are less than 200 µm, extracting metal cations in the presence of eol with a solution of hydrochloric acid and / or sulfuric acid containing 0.1 to 5 grams equivalents of hydrogen ions per liter countercurrently and continuously at 50 ° C to the boiling point of the suspension. of extracted metals with a concentration of 1 to 30 g of metal cations per liter resulting from each stage of the extraction process # has extracted up to 65% by weight of the flood metal content in bsntonite and the surface area min. 150 m ² / g and a pore volume of less than 1,4.10 * m at least 0,1 ml / g, with the acid itself entering the last extraction stage ·

This mode of bentonite activation makes it possible to significantly increase the extraction rate compared to the batch production process by activating a fine grain material with a large surface accessible to chemical reactions and diffusion. With the time of activation ea in the extraction medium, it continually increases the acid concentration and decreases the concentration of extracted metals from the bentonite matrix to the extent that the extracted btontonite obtains a higher utility than in the case of the discontinuous activation process. By continualizing the bentonite activation process, reducing the cost of material compared to the batch production process reduces the material cost, increasing the specific performance of the device #, improving the acid utilization, decreasing the specific epoxy consumption and energy. In addition, a concentrated salt solution with a minimum unreacted acid content that can be used as a waste water flocculant is obtained. The examples given below illustrate but do not limit the scope of the invention.

Example 1

In a 6 L annual vessel equipped with a stirrer, a reflux condenser and a thermometer, bentonite as a suspension of 275 g / l with particles smaller than 200 µm was extracted with 73 g of 100% HCl in liter with stirring at 95 ° C. The extracts obtained after two (E2), four (E4), and three hours (E6) activation after solid phase delay were used as solvents in the countercurrent activation of the bentonite shown in the figure, first filling the reaction vessel (1) with bentonite suepension and A6 extract. After activation for 1.5 hours under stirring at 95 ° C, the activated bentonite was separated from the mother liquor on the separator (51) and the thickened suspension was introduced into reaction vessel no. 2 together with extract A4, where the activated bentonite suspension was extracted for a further 1.5 hours. After separating the extract on the separator (S2), the activated bentonite was mixed in the reaction vessel (3) with the extract A2 and after 1.5 hours of activation with stirring and eeparation of the extract in the separator (S3). Aeparator (S3) was activated with hydrochloric acid alone at 95 ° C for 1.6 hours. In all reaction vessels (1 to 4), the same dry solids concentrations of the bentonite matrix were maintained, i.e. 276 g of dry matter per liter and in an intermediate reaction vessel, the suspension was activated with 73 g of 100% HCl per liter of reaction medium.

The countercurrent activation was carried out three times using the procedure described, using extracts obtained from separators S2 to S4 from each of the previous experiments. After reaching a constant salt content in the aeparator extract (S1) of ca 65 g / l, the activated bentonite from the aeparator (S4) after washing, drying and grinding was tested for its sorption ability and compared to the activated bentonite obtained after 6 hours of concomitant activation by the above-mentioned method (see Table 1). The activated bentonite from the countercurrent activation had a specific surface area of 280 m ² / g and a pore volume

CS 270 828 01 below 1.4.10 " ⁸ m 0.55 ml / g. The bentonite activated by the supercurrent batch process had a futile surface of 209 m / g and a pore volume below 1.4.10 m of 0.29 ml / g.

Example 2 (under the new procedure)

The operational arrangement is based on four activators, each with a reaction rate of 25 m ³ , and the associated separators arranged as shown in the figure filled with a bantonite suspension of 250 g bentonite dry matter per liter with particles below 350 µm of which 80% of the particles are less than 200 µm. The first stage of the cascade is dosed with a concentrated bentonite suspsnity with a flow rate of 0.72 l / a and mixed through the upper outlet of the separator (S1), whose volume flow is 3.8 l / a. Suepension from the activator (1) is dosed with a volumetric flow rate of ca 4.5 l / a into the eeparator (S1), from which the separated mother liquor is discharged for further processing and auapension of bentonite aa successively countercurrently activated by hydrochloric acid degree of activation (4) with a flow rate of 0.72 l / s at a concentration providing 73 g of 100% HCl per liter of reaction medium in this activation stage. · At equilibrium with constant flow rates and optimum separation ratios in the comparators, I <s3. The mother liquor (S1) has a constant residual acid concentration in activated om bentonite at the outlet, and the cascade, after washing with water, analyzes the loss of 39% by weight from the initial metal content of the feedstock, determined in the form oxides.

Example 3 (new procedure)

Starting from four activators each with a reaction volume of 17 m and associated soparators arranged according to Scheme 1 filled with bentonite euspsnity of 260 g bentonite dry matter per liter with particles below 360 µm, of which 60% of the particles are less than 200 µm. cascade of axes dosed thickened euphoria of bentonite with a flow rate of 0.72 l / s and mixed with the upper outlet of the sparger (S2), whose volume flow rate is 3.8 l / s · The suspension is dosed from the activator (1) with a volume flow of ca

4.5 l / s to the separator (S1), from which the removed mother liquor is discharged for further processing and suspsnzia bentonite is successively countercurrently activated in each stage of the cascade with sulfuric acid dosed at a flow rate of 0.72 l / s to the last stage of activation ( 4) at a concentration providing 98 g of 100% H ₂ SO 4 in liter of reaction medium at this activation stage. · At equilibrium with constant flow rates and optimum separation ratios in the separators, ks3 mother liquor from eeparator (S1) has a constant residual acid concentration of in activated bentonite at the outlet of the cascade after washing with water, the analyzed loss of 48% by weight of metals from the original metal content of the feedstock, determined in the form of oxides. .

Example 4 (serves to illustrate and compare the current activation procedure) a

In a 34 m activator, hydrochloric acid of an initial concentration of 73 g of 100% HCl in a liter of reaction medium is activated bentonite 8 with a concentration of 250 g of bentonite dry matter per liter with particles below 350 µm, of which 80% were less than 200 µm during 6 hours at the boiling point of the suspension. From the activated bentonite matrix, after filtering the mother liquor and washing with water, the% wt% metal loss from the initial metal content of the feedstock determined in the form of oxides was analyzed.

Example 3 (to illustrate and compare the current activation procedure)

In a 6 L activator, sulfuric acid at an initial concentration of 98 g 100% H ₂ 30 ₄ in a liter of reaction medium activates bentonite auapension at a congestion of 250 g bentonite dry matter per liter with particles below 350 µm, of which 80% were more than

200 µm, for 4 hours at boiling point of suspension · From the octivovonoj bontonite matrix, after filtering the mother liquor and washing with water, the loss of 25% by weight of metals was analyzed

CS 270 828 81 from the initial metal content of the feedstock determined in the form of oxides.

From table no. 1, where the sorption capacity of activated bantonites prepared according to Examples 1 to 5 is compared, it is evident that countercurrent continuous activation over batch batch activation increases the absorbent capacity of activated bentonite.

Table no. 1 Sorption ability of activated bentonites Example co-current 1 countercurrent 2 3 4 5 Decolorizing effect on raet. oil according to ČSN 721599 in% 96.9 102.1 101.8 102.3 97.8 96.3 Decolorizing efficiency on petroleum oil, according to ČSN 721599 in% 86.2 119.0 129.0 133.4 84.0 89.2

OBJECT OF THE INVENTION

Claims (1)

Process for the continuous countercurrent activation of bentonite by cyeelines, characterized in that it proceeds in two to four stages from the bentonite matrix entering the first stage in the form of a suspension containing 150 to 500 g / l of dry matter, in which min. 70% of the particles are less than 200 µm, and extract a lotion of metals in the presence of a solution of 9 to 10 g / l sulfuric acid containing 0.1 to 5 grams of hydrogen ions per liter countercurrently and continuously at 50 ° C to the boiling point of the suspension. salts of extracted metals with a concentration of 1 to 30 g of metal cations per liter resulting from the individual stages of the extraction process, until a maximum of 65% by weight of the flood metal content in the bentonite has been extracted and a min. 150 m ² / g and a pore volume of less than 1.4.10 ° m of at least 0.1 ml / g, with acid entering the last stage of extraction.