PROCESS AND EQUIPMENT FOR THE PERFORMANCE OF PRECIPITATE FORMING REACTIONS BY USING AN ION-EXCHANGE AUXILIARY PHASE

Abstract: The essential feature of the process according to the invention lies in that solid crystalline matters, respectively precipitates are gained from the solution by means of chemical reactions, in such a manner, that at least one of the components, the ions, forming the precipitate being slightly soluble in the liquid medium or inducing respectively promoting the chemical reaction between the compounds being present in the solution, is introduced into the system bound to the ion-exchange material, while this material serving as an ion-exchange auxiliary phase, is brought into contact with the solution containing the other component(s) forming the precipitate, or the ion-exchange materials containing individually the components forming the precipitate are brought together in a liquid medium and by the partial recirculation and/or by bringing repeatedly into contact with the ion-exchange auxiliary phase and the solution, the grain size of the precipitate can be increased, simultaneously filtrability may also be improved. The essence of the equipment being suitable for the realization of the process according to the invention lies in, that within the apparatus-body spaces are formed by means of partitions lying perpendicularly to the material stream, in the bottom there are the apertures interconnecting said spaces, while in the upper third of the partitions studs -protruding into the confining space and being connected to gas - or air distributing organs - are arranged; in the bottom of the single spaces means for distributing the gas or air are to be found; further on, the equipment is provided with an aerolift with a passage opening leading to the last space of the apparatus; the apparatus is futhermore provided with studs for the discharge of the material and outlets for the gas and air. The advantage of the invention lies in, that precipitates with an increased grain size, tending to a spontaneous flocculation may be obtained, simultaneously the purity of the precipitates formed is far higher, than that of the precipitates having been gained in course of usual processes.

Description: Process and equipment for the performance of precipitate forming reactions " by using an ion-exchange auxiliary phase Field of the invention The invention relates to a process for producing preci¬ pitates with, an increased grain size, with improved sedimentation characteristics and a " better filtrability and/or a higher grade of purity by using an ion-exchange auxiliary phase; the invention also relates to the equipment being suitable for performing said process. Background of the invention The essence of the chemical reactions resulting in ' pre- ci -n**itate formation lies in that after having __• nix _ed the solutions containing the anion forming the precipitate to be isolated and the cation, respectively, the solid product of reaction having been formed under the influence of the chemical reaction talcing place in the solution phase, precipitates from the solution being supersaturat¬ ed in respect to the poorl2 soluble compound. The preci¬ pitate is .formed from the reaction product in course of the nodule formation, nodule growth and agening; under agening the coagulation, as veil as the Ostwaldian agening is meant /see Nielsen, A. ■ _). : Kinetics of Precipitation, Pergamon Press, 1964/. The grain size distribution of the precipitate is determined by the enumerated partial pro ¬ cesses, out of which the ratio of the velocity of nodule formation and nodule growth can be considered as the most important factor, when in general, the velocity of the nodule formation is considerably higher, than the velocity of nodule growth. The reactions resulting in the formation of precipitates serve namely for the production of compounds of poor solubility and it is a well-known fact, OMPI that the lower the solubility of the compound formed, the higher the velocity of nodule formation. Furtheron, in course of mixing' the reagents local supersaturation cannot be avoided, resulting also in an increased velocity of the nodule formation, while the growth of the nodules and the small-sized precipitate grains is hindered by the electrolyte layer having been formed thereon. The small grain size of the precipitate formed is to be considered as unfavourable and disadvantageous not only with regard to further processing, as sedimentation, filtration, drying, etc. but often it results in incon¬ venience in course of the final utilization. The accompany ing ions getting into the process together with the reagen may deteriorate the purity ' of the product, penetrating into the inclusions or infiltrating into the lattice or being adsorbed on the surface they are tending to contamin the precipitate. Technicians dealing with the problem of precipitate for¬ mation have tried long ago to develop methods, by the aid of which the problems referred to may be eliminated. The relating research work has been performed fundamentally in two directions. Partly processes for the formation of precipiates in a heterogenous phase have been elaborated, in course of which local supersaturation has been del 3r- ed by an interphase material transfer resp. a heterogenous chemical reaction prior t'o the formation of the precipitat The essence of these solutions lies in that one of the components needed for the precipitate formation is added in the gaseous or solid phase to the solution con- taining the other component. However, the scope of application of said methods is considerably restricted by the fact, in so far as with the majority of the pre¬ cipitate forming processes suitable gaseous or solid reagents are not staying at disposal. O - 2 - Other fundamental research works tended to the develop¬ ment of the diverse methods of homogenous precipitate formation. The essence of the process for the homogenous precipitate formation lies in that one of the components forming the precipitate is produced directly in the solution by the hydrolysis of one of the staifclng materials or of an auxiliary material or by the resolution of a complex compound containing the given component..- By using this method, formation of local supersaturations can be avoided, at the same time it can be considered as dis¬ advantageous, that in certain cases the process can be controlled but v/ith difficulties. The field of application of homogenous precipitate for¬ mation has been restricted by the fact, in so far as for the dosage of the reagent component a compound being able to resolve in a given solution v/ith a controllable velocity is to be found. At almost all the heterogenous and homo¬ genous precipitating processes the presence of the foreign components contaminating the isolated precipitate cannot be avoided either. Zssence of the invention The process according to the invention is based on the surprising recognition that if at least one ion out of the ions forming the precipitate, cr at least one of "the ions inducing the chemical reaction between the com¬ ponents contained in the solution resulting in the format¬ ion of the precipitate and promoting it, respectively, is introduced into the system bound to a ion-exchange ma¬ terial, precipitates of an increased grain size and/or tending to a spontaneous coagulation and/or of a greater purity can be obtained, furtheron, by the partial re- circulation of the precipitate having been obtained in such a manner and/or by subjecting the suspension with a - *r - precipitate to a heat treatment, sedimentation and filtrability can be further improved. The essence of the process according to the invention lies in that crystalline substances and precipitates, respectively, are gained from a solution, by means of a chemical reaction in such a manner, that at least one ion ' out of the ions forming the precipitate to be produced or at least one ion inducing the chemical reaction between the components contained in the solution or promoting the same, is introduced into the system bound to an ion- exchange material and the ion-exchange material serving as an ion-exchange auxiliary phase is brought into contact with the solution containing the other ions forming the precipitate; it is also possible to bring together the ion-exchange materials containing individually the ions forming the precipitate in a suspension, while formation of the precipitates is taking place and in a given case, by the partial recirculation of the precipitate and/or by a repeated contact v/ith the ion-exchange material and the solution, both the grain size can be increased and the filtrability improved. The ion-exchange auxiliary phase to be used in course of the process is either a natural or an artificial anion- ch-anging or cation-changing substance being present in a solid granular and/or gel and/or liquid state. In course o the process contact between the solution, the ion-exchange auxiliary phase and the precipitate is established in one or more stages; in case of more stages, the precipitate formed is advantageously recirculated between the single stages, i. e. it is brought repeatedly into contact with the ion-exchange auxiliary phase and the solution. In a given case, in course of establishing the contact between the ion-exchange auxiliary phase, the solution and the precipitate dissipation heat transfer or heat exτraction - KE O P is applied. By using methods known in itselves, the mixture containing the precipitate formed, the ion- exchange auxiliary phase and the solution are separated; the ion-exchange material is regenerated in a well-known manner, i. e. by bringing it repeatedly into contact v/ith the solution, it is brought in a state being suitable for the formation of the precipitate and it is used in the system once again. Several types of equipments have been known for the realizat- ion of crystallization and within this field for the ctys- tallization accompanied by precipitate formation. Por the realization of the traditional processes for producing precipitates mechanical agitators, i. e. cascaded mixers have been widely used. The reason for this is that in order to be able to avoid local supersaturation in course of the precipitate formation, the primary aim was to achieve the intensive stirring of the reagents, however, the dis¬ integrating effect of the intensive mixing resulted in a decreased grain size. This endeavour for the intensive contact is to be observed at the application of the rotary film-apparatuses; in said apparatuses mixing of the reagents can be well realized, at the same tine the desintegrating effects resulting in a reduced grain size are utmost strong. Cut of the different types of the crystallizing equip¬ ments we refer - among o.thers - to the cooler bubble crystallizer having been described in the DE-PS 1 084 240, in which mixing of the slurry is performed by introducing air through a nozzle into the central casing pipe having been arranged within the c^^lindrical apparatus-body, while the internal circulation of the crystal-sluri- may be controlled by the streaming veloci 2- of the air and the product is discharged on the lower part of the apparatus. In the Czechoslovakian Patent Ho. 154 129 a continuously working crystalllzer - having been developed for the sugar industry - is specified. The essential feature of the equipment lies in that in a horizontal recipient spaces are formed, the volumes of which are increasing in the direction of streaming and the single spaces are provided v/ith heating elements in their upper part, while on the bottom a horizontally arranged agitator is keeping the crystal suspension in motion. The proportion between volume and heating surface is selected in such a manner that the dv/elling time of the suspension should be the same for all spaces. Purtheron, so-called slurry-circulating crystallizers for the realization of crystallization in vacuum are also known; the essential feature of these equipments lies in, that the intensive recirculation of the crystal-slurry is achieved by means of a propeller-agitator having been arranged in a central casing pipe; such equipments are described in the publications Ind. Ing. Che . 53.115.1961 /Calάwell, H. B./ and Chem. Eng. Progr. 55.65.1959 /i-Tewman, Bennett/. One of the most important requirements the equipment according to the invention has to comply with is, that a suitable contact could be established between the ion-exchange auxiliary phase, the solution εnd the pre- cipitate. However, if only this one single fundamental requirement had to be met, as a matter of fact, any equipment provided with a known mechanical agitator or pneumatic mixer could be expediently used. However, ~ oγ meεns of said equipments the advantages cf our process, namely the recirculation of the smaller grains and the well-timed heat treatment of the suspension containing the precipitate resulting in a further increase of the grain size and improved sedimentation and filtration characteristics as well, could not be achieved. By using the conventional equipment types, said effects could be achieved only by connecting several equipments in series, however, in this case the partial separation of the materials, i. e. the isolation of the fractions of smaller grain size, as v/ell as transport of the material betv/een the single equipments v/ould be v/earisome, besides the installation of separate equipments v/ould be necessary. The equipment being suitable for the realization of the process according to the invention is based on the recognition, that by forming individual spaces within an apparatus-body by inserting vertical partitions, the of smaller grain size can be recirculated from the spaces having been already agitated into the preceding space through the apertures on the upper part of the partitions, whereas the ion-exchange & ~ _u__.li&τ ~ f phase and the suspension containing the crj'stals of larger particle size are passing forwards through the apertures on the lower part of the partitions, from space to space, and in accordance v/ith prevailing necessity, in the single spaces dissipation heat transfer or heat extraction may be applied. By means of the equipment the establishment of the contact between the ion-exchange auxiliary phase, the solution and the precipitate formed in several stages, as v/ell as the selective recirculation of the precipitate of small grain size between the stages following each other, the increase of the grain size and the improved filtrability of the precipitate nay be achieved. In course of the formation of the precipitate the ion- exchange material may be a granular solid matter or a gel or a material in a liquid state not intermixing v/ith the solution. In connection v/ith the ion-exchange material the following requirements are to be met: — the ion required for the precipitate formation should be bound with a satisfactory capacity; — establishment of the contact v/ith the solution should be possible; — the ion-exchange material could be well isolated from the suspension containing the precipitate. In course of precipitation formation the ion exchanging material functions as an auxiliary phase; first of all it is saturated v/ith one of the ions needed for the format ion of the precipitate, thereafter it is brought into contact v/ith the solution containing the other ion needed for the formation of the precipitate and after having been isolated, it is regenerated. In course of the precipitate formation with ion-exchange the ion-exchange material can be evenly distributed in the entire volume of the solution, as a consequence, local supersaturation can be avoided. The possibility of local supersaturation is further reduced by he fact, in so far as the access of the reagent ions into the solution is delayed by the velocity of diffusion and ion-exchange reaction, v/hich is less than the velocit3 r of the chemical reaction, in such a manner the ion- exchange material is quasi slowly dosing the ions needed for the precipitate formation. The other essential characteristics of the precipita-te formation v/ith ion-exchange lie in, that the ion-exchange material is binding the "accom ring ion ;ι being present in the solution, as a consequence, in the solution phase of the suspension containing the precipitate - with the proper proportions of dosage - the concentration of the cation accompanying the anion forming the pre¬ cipitate and the concentration of the anion aceempal¬ ing the cation forming the precipitate can be reduced to the minimum. As a consequence, on the surface of the isolated precipitate grains the electrolyte layer i- ~ formed to a slighter extent or there is no electrolv e - ¬ at all; in such a manner — the growth of the small grains of the precipitate will be less restricted, — by the recirculation the size of the smaller grains can be increased, — by heat-treating i. e. by agening the grain size may be increased, — by heat-treating i. e. by agening the grain size may be increased, — to a certain extent the precipitate tends to spontaneous flocculation, coagulation. By using the process according to the invention, the crystallization v/ith precipitate formation is well suitable for producing compounds of a higher puritΛ r , since by using pure reagents the adhesion of the accompanying ions onto the surface of the precipitate grains can be avoided, thus the infiltration of the foreign ions into the lattice and/or into the in¬ clusions does not take place. In course of the precipitate formation with ion-exchange precipitates v/ith a larger grain size and tending to spontaneous coagulation may be obtained - and compared to the precipitates produced by the usual precipitating processes -, they are showing improved sedimentation and filtration characteristics. By these measures partl3 r the separation of the precipitated solid matter is facilitated, partly further processing of the precipitates takes place in a more advantageous manner, including drying, packing and even final use. The process according to the invention is more suitable for separating different materials by precipitate format¬ ion, than the traditional precipitating methods. The - JLU - primary reason for this is, that partly due to the more uniform distribution of the ion-exchange reagent, partly owing to the velocity defining character of the ion-exchange, local supersaturation may be avoided, and the concentration of the reagent ion can be more accurately controlled. Por instance, by using a ion- exchange material of the hydroxide type, the process is yielding the possibility for the performance of preci¬ pitate forming isolations based on the pH-selective hydrolysis. Short descri-ption of the figures The equipment being suitable for performing the pro¬ cess " according to the invention will be described in detail by means of a preferred embodiment, by the aid of the accompanying drawings, wherein: figure 1 is showing the sectional front view of the equipment, figure 2 the sectional op- iew and figure 3 the side-elevation of the equipment, figure 4 is showing the schematical flow diagram of the equipment and the ancillary units. Descriυtion of the preferred embodiments Referring to figures 1 to 5, the apparatus-body 1 is divided into two or more spaces 3 by means of one or more vertically arranged partitions 2. The pipe su 4 provid¬ ed v/ith the nozzle 5 and overhanging into the confining space 3 is connected to the aperture in the upper third of the vertical partition 2. At the lower part of the space 3 the vertical partition 2 does not extend to the bottom of the apparatus-body 1, v/hereby the apertures connecting the single spaces 3 are formed. At the bottom of the single spaces 3 there are the perforated air- distributing pipes arranged, to which the air- conducts 8 have been connected. Approximately in its lower third part the apparatus-body 1 is shaped v/ith 5 the restricted cross-section 9. In the last space 3 /indicated by III in figure 1 and by v " in figure 4/ the bottom of the apparatus-body 1 is connected via the aperture 11 to the aerolift 10, at the bottom of which the air blower 12 is to be found. The space of 10 the aerolift 10 is connected via the return aperture 13 to the last space 3; the aerolift 10 is provided v/ith the material discharge pipe stud 14 and the air αut- let-stud 15. Referring to figure 4, the solution 16 containing one 15 or more components of the precipitate to be isolated, as v/ell as the ion-exchange auxiliary phase 17 con¬ taining the ion/s/ inducing or promoting the reaction resulting in precipitate formation, are led into the first space 3 of the apparatus-body 1. The solution 20 having been introduced into the first space 3, the ion-exchange auxiliarj-" phase, as vell as the precipitate formed travel through the apertures 6 formed in the lower part of the vertical partitions 2, from space to space orwards, from the space marked v/ith I to the 25. space:3 marked v/ith V. In the single spaces 3 nixing is performed by the air stream introduced via the perforated pipes 7 /nozzles/ having been arranged in the spaces each, along the longitudinal axis of the apparatus-body 1. The air stream is delivered by the 30 air conducts 8. By the controlled position of the nozzles and by the geometrical shape of the lower trapezoidal cross-sectien 9 of the apparatus-body 1 a circ n ." .ating stream may be obtained in the single compartments. 3 the aid of the pipe studs 4 and the nozzles 5 having een connected to the apertures in the U " PΌΘΓ third part OMPI of the vertical partition 2, selective recirculation of the small-sized grains from the last space 3, i. e. from the aperture 13 of the aerolift 10 up to the first space 3 can be realized. The isolated precipitate, the ion-exchange material and the solution are led away from the last space 3 through the passage opening 11 on the bottom of the apparatus-body 1, by the aid of the aerolift 10, which is receiving the delivery air through the nozzle 12. The constant level of the suspension in the apparatus-body 1 is controlled by means of the opening 13 of the aerolift 10. The solid matter and the materials in a liquid state ' are leaving the aerolift 10 through the stud 14, while delivery air is discharged via the stud 15. The quantity of the ion-exchange material and the precipitate, respectively, dwelling in the appa¬ ratus-body 1 can be advantageously controlled by changing the size of the opening 11 resp. 13 and the quantity of the air to be introduced via the nozzle 12. The suspension mixture consisting of the ion-exchange auxiliary phase, the isolated precipitate and the solution having been discharged through the stud 14 of the aero¬ lift 10 arrives expediently at the vibroscreen 18, when a granular ion-exchange material is used; the granular material is thus separated and the solution v/ith the pre- cipitate is passing through the vibroscreen 18 and is led to the screen 19, where the precipitate is isolated from the mother lye solution 21. In case of necessity, a part of the mother lye is recirculated to the vibroscreen 18 in order to be able to wash out the ion-exchange resin /indicated v/ith a dashed line in figure 4/. In case, if a ion-exchange auxiliary phase in a liquid state is used, the suspension mixture consisting of the ion-exchange material, the isolated precipitate and the solution, is led firstly to the equipment separating the solid matter, e. g. to the screen 19 or the centrifuge, where the precipitate is isolated; thereafter the mixture consist¬ ing of the solution and the liquid ion-exchange ma¬ terial is separated in an equipment not illustrated here, e. g. in a liquid separator or a decanting apparatus. It goes without saying, that in a given case the single components can be separated from the suspension mixture in a different order of sequence, by using any optional equipment. " When using ion-exchange materials in a liquid state, the last spaces of the apparatus can be utilized as sedimentation stages without stirring. Thereafter the ion-exchange material to be regenerated is led into the ion-exchanger 22, which can be any type of the known ion-exchangers. The regenerating reagent is dissolved in the reservoir 24, from where it is de¬ livered by means of the pump 25 into the ion-exchanger 22. In case of necessity, the regenerated granular resin is washed on the vibroscreen 26 v/ith the water having been used for preparing the regenerating solution, hereupon it can be repeatedly used as an ion-exchanger auxiliary phase for the process of precipitate formation. The spent regenerating solution 27 is drained and within the range of possibilities the useful components are recovered. In a g.ven case, the mother lye can be also used for preparing the regenerative solution. As already mentioned before, the cross-section of the apparatus-bod;/ 1 lying perpendicularly to the material stream may be shaped as a trapezoidal crocs-section 9 or as an arched restricted part or as a rectangle in the full height of the apparatus-body, in addition to these, the bottom of the apparatus-bod;/ may be formed with a convex surface. The apparatus-body 1, showing expediently an oblong top-view, is divided into smaller parts with a square or oblong cross-section by means of the partitions 2. The partitions 2 are arranged normal to the streaming direction of the material and in a case of necessity they may be prepared as interchangeable parts. The partitions 2 are forming a continuous aperture at the bottom of the apparatus-body 1, whic enables the advance of the ion-exchange auxiliary phase, the solution and the precipitate of larger grain-size from one com¬ partment to the other. The stream of the materials is induced by the spontaneously formed hydrostatical differential pressure, in general, special means are not required, hov/ever, the use of such means for producin the stream is not excluded at all. On the upper part of the partitions 2, preferably in the upper third belov/ the level of the solution one or more apertures are provided serving for the recirculat¬ ion of the precipitate grains of smaller size being present in the upper part of the solution space into the preceding space. Recirculation is obtained in such a manner, that a stud - bent downwards expediently by 90 - is connected to said aperture/s/, into which a strea of air or gas is led through e. g. a nozzle, while the solution containing the precipitate is pneumatically circulated to the precedent space. The rate of recirculat ion may be controlled by the size of the stud and the quantity of the gas introduced. In this single spaces pneumatic agitation is performed e. g. in such a manner that on the bottom of the single spaces, in the direction of the material stream gas- or air-distributing pipes being closed on both ends are arranged and the gas stream needed for the agitating activity is led through the perforations on the mantle of the pipes into the solution space. Perforation may be formed in one or two rows. In so far as the perforations O - WIP \ are formed alon ' the length of the pipe, along a generatrix having been rotated by 30-60° in relation to the vertical plane, an internal circulation may be produced by means of the air stream in the apparatus- body v/ith the trapezoidal cross-section. In the spaces of the apparatus pneumatic agitation may be performed by using an internal casing pipe, or nozzles or any equivalent means, or in a given case mechanical agitat¬ ion can be performed. In general, the ion-exchange material and the solution/s/ needed for the precipitate formation are led into the first space falling into the direction of the material stream, hov/ever, it is possible to introduce the material into an other space or simultaneously into more spaces. The materials are discharged from the apparatus-body 1 through the last space by means of the aerolift, which is connected to the lower part of the space. The suspension is led into the aerolift through the opening on the bottom of the apparatus-body, simultaneously - for keeping a constant level - betv/een the aerolift and the apparatus- body a further passage is formed in the height of the solution level. By this structural solution and. the re¬ sulting constant level the selective outlet of the larger- sized precipitate grains is ensured. By the v/ell co- ordinated change of the size of the opening connected to the aerolift and the quantity of the deliver; 7 " air, the quantity of the ion-exchange material and of the preci¬ pitate can be v/ell controlled, while the level of the solution is kept constant. Yvhen a granular ion-exchange material is used, the ion- exchange resin and the solution with the precipitate are simultaneously discharged from the apparatus and separat¬ ion is to be performed separately. By the proper.-selection of the grain size of the ion-exchange resin it becomes possible to isolate the solution v/ith the precipitate from the ion-exchange material of large grain size by using a vibroscreen. In case of ion-exchange materials in a liquid state, the last spaces of the apparatus may serve as sedimentation stages without agitation. In such a manner the separated outlet of the isolated ion-exchange phase becomes possible, taking place - in dependence of specific weight conditions - in the upper or lower part of the apparatus-body. Por the sake of order it should be mentioned, that the process and the apparatus according to the invention may be used not only for producing inorganic compounds, but both can be successfully applied for the production of compounds, which are slightly soluble in water and one of the components is an organic, the other an in¬ organic substance.- Indeed, the most general form of the invention relates to a process for producing precipitates in a liquid solvent medium from organic and/or inorganic components, which are insoluble or slightly soluble in said solvent, in course of which one or more components dissolved in the solution are allowed to react with the component being present in the ion-exchange auxiliary phase in a bond ferm or v/ith ion-exchange materials containing individually the precipitate forming components, In order to facilitate the comprehension of the invention, it will be described by means of some examples without the character of restriction. Example 1 for preparing ferric/III/ hydroxide precipitate a/ Por the sake of comparison precipitation is performed in the usual manner by adding 60 ml sodium hydroxide solution of the concentration of 5 mole/1, at a dosage rate of 2 ml/minute, -to 200 ml ferric/III/chloride solution of the concentration of 0,5 mole/i, thereafter the suspension is allowed to stand for 50 minutes. b/ To 200 ml ferric/III/chloride solution of the con¬ centration of 0,381 mole/1, at a dosage rate of 4 ml/min 200 ml Varion-A-D resin is added, which contains 21 g/1 OH "" " ions ' . After having been stirred for 50 minutes, the resin is isolated on a 0,6 mm screen. c/ 100 ml suspension having been prepared according to b/ are mixed with 100 ml ferric/III/chloride solution of the concentration of 0,381 mole/1, thereafter - at a dosage rate of 4 ml/minute - 100 ml Yarion-AB resin are added, which contain 21 g/l OH " ions. After having stirred the mixture for 30 minutes, the resin is isolated on a 0,6 mm screen. d/ 100 ml suspension having been prepared according to c/ are mixed with 100 ml erric/III/chloride of the concentration of 0;381 mole/1, thereafter - at a dosage rate of 4 ml/minute - 100 ml Yarion-AD resin are added, whic contain 21 g/l 0H~ ions. After having stirred the mixture for 30 minutes, the resin is isolated on a 0,6 mm screen. e/ 200 ml suspension haying been prepared according to a/ are mixed with 100 ml Yarion-AD resin of a hydroxide form and 135 πl hydrogenous Yarion-H S resin. After having ' oeen stirred for 60 minutes, the resin is isolated on a 0,6 mm screen. f/ The suspension in a quantity of 200 ml having been ■ prepared according to a/ is heated to 50 °C, there¬ after it is cooled to 20 °C in 30 minutes. g/ The suspension having Oeen prepared according to b/ is heated to 50 C and thereafter it is allowed to cool to 20 °C in 30 minutes. In all cases enumerated above, the suspension contained solid matter in a quantity of 40 g/l. In order to be able to test sedimentation properties, in all cases 200 ml each of the suspensions v/ere filled in a 40 cm high cylinder v/ith a useful volume of 200 ml and the change of the solid matter content in the sedi ented layer was determined in dependence of the time elapsed. The results obtained are summarized in the table belov/, in which the contained solid matter obtained in the single intervals are related to the suspension having been prepared 'in accordance v/ith a/. Solid matter Solid matter content sub¬ content related sequent to to the suspension εedi entation /kg/m3/ Sedimentation period s /__._./ 20 60 110 20 60 110 a/ 43,5 52,2 54,6 1 1 1 b/ 55,9111,0 131,6 1,28 2,15 2,4 c/ 59,30102,9 145,7 1,36 1,97 2,6 d/ 60,4150,6 148,4 1,40 2,50 2,7 -I 51,0 88,2 109,5 1,17 1,69 2,0 χ 7 44,2 53,2 55,2 1,02 1,02 1,0 g/ 63,0135,80 158,4 1,45 2,56 2,9 In order to be able to compare filtrability properties, the suspension having been prepared in the previously described manner are filtered under a vacuum of 600 Torr in a nutsch-filter covered with a filter cloth ø 6 cm 2 and v/ith a surface of 28,3 cm ; the timely change of the filtrate volume Is measured. The following table is showing the average rates of filtrating for the filtering periods of 1 minute and 6 minutes, respectively, as v/ell as the rates of filtrating related to the suspension a/. Average rate of Rates of filtrating filtrating related to the /m 3 /m 2 /h/ suspension a/ Piltering period /minutes/ 1 6 1 6 a/ • 0,318 0,265 1 1 V 1,04 0,474 3,27 1,79 -I 1,13 0,488 3,55 1,84 d/ 1,17 0,495 3,68 1,87 e/ 0,566 0,361 1,78 1,56 ι7 0,425 0,297 1,34 1,12 g/ 1,91 0,515 6,01 1,94 for preparing a barium sulfate precipitate a/ Por the sake of comparison, precipitation is performed in the usual manner, by adding at 20 °C and v/ith a plϊ value = 2 19,5 ml sodium sulfate solution of the concentration of 2,0 mole/1 - at a dosage rate of 0,5 ml/minute to 200 ml barium chloride solution of the concentration of 0;195 mole/1 while continuously mixing, thereafter the suspension is mixed for a further 50 minutes. b/ 200 ml barium chloride solution of the concentration of 0,175 mole/1 are mixed v/ith 80 ml Yarion-AP resin containing 68 g/l sulfate ions at a dosage rate of 2 ml/ in. After having been stirred for 50 minutes, the resin is isolated on a 0,6 mm screen. c/ 100 ml suspension having been prepared according to b/ are mixed with 100 ml barium chloride solution of the concentration of 0,175 mole/1, thereafter 40 ml Varion-AP resin containing 68 g sulfate ions/1 are added at a dosage rate of 1,0 ml/minute. After having been stirred for 30 minutes, the resin is isolated on a 0,6 mm screen. d/ 100 ml suspension having been prepared according to c/ are mixed v/ith 100 ml barium chloride solution of the concentration of 0,175 mole/1, thereafter 40 ml Yarion-AP resin containing 68 g sulfate ions/1 are added at a dosage rate of 1,0 ml/minute. After having been stirred for 30 minutes, the resin is isolated on the 0,6 mm screen. e/ 200 ml suspension having been prepared according to b/ are mixed v/ith 107 ml Yarion-A-D resin of the hydroxide form. After having been stirred for 60 minute the resin is isolated on a 0,6 mm screen. f/ 200 ml suspension having been prepared according to a/ are heated to 50 C, thereafter the suspension is allowed to cool to 20 °C in 30 minutes. g/ 200 ml suspension having been prepared according to b/ are heated to 50 °C and allowed to cool to 20 °C in 30 minutes. In all cases the suspension contained- solid matter in a quantity of 40 g/l, In a manner having been described in detail in connection with Example 1, sedimentation and filtrability characteristics have been determined by means of comparative tests; the results are summarized in the following tables. Solid matter content Solid matter content subsequent to related to the sedimentation sample a/ kg/m- 5 Sedimentation period - 10 20 60 10 20 60 /minutes/ a/ 47 : ,07 55,08 70,51 1 1 ' 1 V 51. ,80 83,72 144,54 1, ,10 1,52 2,05 c/ 53 ; , 66 88,13 155,12 -*-! ,14 1,60 2,20 d/ 55 ; ,60 93,64 165,70 1. ,18 1,70 2,35 e/ 48. ,50 58,38 77,56 1, ,03 1,06 1,10 ±7 53 : ,19 90,33 148,07 1. ,13 1,64 - 2,10 g/ 62, ,15 117,87 170,63 1, ,32 2,14 2,42 Average rate of Rate of filtering filtration related to the /m3/m 2 /h/ sample a/ Filtering period 1 6 1 6 /minutes/ a/ 0,330 0,266 1 ' 1 V 1,445 0,460 4,38 1 : ,73 c/ 1,610 0,468 4,88 1, ,76 d/ 1,655 0,474 5,01 1; ,78 e/ 0,690 0,350 2,09 1, ,32 χ 7 1,016 0,442 5,08 1: ,66 g/ 2,520 0,640 7,63 2. ,40 -^URE ^ OMPI - ' ά ' ά - Example 5 for producing a lead sulfate precipitate by using an anion-exchange material in a liquid state 200 ml of the aquaeous of lead acetate of the concentrat- 5 ion of 0,1 mole/1 are shaken up with petroleum contain¬ ing trioctyl-methyl-ammonium sulfate in a concentration of 0,1 mole/1. As a surface active agent 0,1 weight % n-octyl alcohol is admixed to the mixture. In course of contacting the phase, 5,3 g lead sulfate precipitate 10 . is formed, while the liquid ion-exchange material - not intermixing v/ith the aquaeous solution - is taking up the acetate form. The grain size of the precipitate formed - compared to that of the precipitate gained in course of the traditional processes - is larger, simul- 1 taneously the precipitate can be better filtered. Example 4 for the production of anhydrous cupric sulfate in a non-aquaeous medium To 200 ml ethyl alcohol containing cupric/II/chloride 20 i a concentration of 0,1 mole/1, at a dosage rate of 5 ml/minute, 35 ml Yarion-AP resin /having been pre¬ viously expanded in alcohol/ containing 63,8 g sulfate ions/1 are added. After having finished dosage, the mixture is heated under continuous stirring to 40 C; 5 thereafter it is allowed to cool to 20 °C and it is mixed for 30 minutes. In the ethyl-alcoholic solution 2,92 g anhydrous cupric sulfate are formed, while the • ion-exchange material is converted into the chloride " form. 0 Example 5 for the selective preparation of aluminium hydroxyde, magnesium hydroxide and iron hydroxide precipitates OM Under stead;?- stirring Yarion-AB resin containing 18 g/l hydroxide ions is added to 200 ml aquaeous solution containing 0,1 mole/1 aluminium sulfate, 0,1 mole/1 iron/III/chloride and 0,1 mole/l magnesium sulfate, meanv/hile the pH-value of the solution is continuously controlled. After having introduced the ion-exchange resin in a quantity of 62 ml, the mixture is separated. The ferric/III/- hydroxide precipitate formed, v/eighing 2,1 g in a dried state, is to be analysed. The purity of the isolated ferric/III/hydroxide surpassed 99,8 . After having admixed further 125 ml ion-exchange resin to the solution, the mixture is separated and the pre¬ cipitate formed - aluminium hydroxide v/eighing 3,0 g in a dried state and contaminated by 0,21 .-_ ferric/IIl/- oxide and 0,03 % magnesium oxide - is isolated. After having added a further 45 nil ion-exchange resin to the solution, magnesium hydroxide precipitate is isolated, v/eighing 1,1 g in a dried state, containing 0,005 . - ferric/III/oxide and 0,012 •.-. aluminium oxide as contaminations. Example 6 for roducing aluminium hydroxide precipitate in the apparatuses to be seen in the fi --_g__ures Into the space I of the apparatus according to figure 1 and 2, having been built up of spaces with a cross- cection of 0,1 m x 0,1 m and of the height of 0,8 m, at a dosage rate of 2 1/h aluminium sulfate solution in a concentration of 0,245 mole/1 and Yarion-AD ion- exchange resin v/ith a grain size> 800 micron are fed at a dosage rate of 3 1/h. Prom the space indicated v/ith III the suspension is discharged and the resin contained therein is isolated on a vibroscreen covered 2 with a filter cloth of the surface of 250 cm , with a eshsize of 600 micron. The resin-free suspension is sedimented and filtered. After having sedimented the suspension containing 38,4 g solid matter per litre for 50 minutes, the solid matter content increased to 243 g/l. The initial-filtrating rate of the solution containing the precipitate amounts to 2,1 _?/_? ■ /_., Example 7 for producing manganese-oxy-hydroxide precipitate in the apparatus as illustrated in the figures Into the space I of the apparatus to be seen in figure 1 and 2, respectively, assembled of spaces v/ith a cross- section of 0,1 x 0,1 m and of the height of 0,8 , 0,25 mple/1 I-In/II/ions, a petroleum solution contain¬ ing 0,5 mole/1 di-/2-ethyl-hexyl/-phcsphoric acid and an aquaeous sodium hydroxide solution /concentration: 0,25 mole/1, rate of dosage: 4 1/h / are introduced. In the apparatus contacting of the phases, recircuiat- ion of the small-sized grains, partial oxidizing of the nanganese hydroxide precipitate, as well as discharge of the substances having been subjected to the reactions and containing the precipitate have been performed by means of air streams in a manner having Oeen indicated in the figure. The petroleum phase was separated from the mixture having been discharged from the space III of the apparatus. The sedimentation and filtration charac¬ teristics of the aquaeous phase containing the pre- cipi a e v/ere tested. After having sedimented the suspension with a solid matter content cf 20,2 g/dn- 5 for 50 minutes, the solid matter conten Increased to 122 g/dm3. The initial rate of filtering amounted to 5,4 _ I _?-/_. _ OM -/λ Por the sake of order it should be mentioned, that by increasing the number of the spaces of the apparatus according to figure and to Example 7 and using them as sedimentation spaces without performing agitation, separation of the phases and partial sedimentation of the suspension containing the precipitate, respectively, can be performed in the same equipment. Summing up what has been said, the advantages of the invention are as follows: - due to the more accurate dosage and more uniform dis¬ tribution of-the ion-exchange material local super- saturations can be avoided; - sedimentation and filtrability characteristics may be further improved by using, flocculating agents, which are efficient even in lower concentrations, than usual; - precipitates v/ith a larger grain size and. tending to flocculation may be produced, the rate of sedimentation which, is 2-3-times higher, and the rate of filtration is 6-8-times higher, than with precipitates having been isolated in course of the traditional process; - in course of the isolation the disturbing effect of foreign ions may be eliminated resulting in a higher purity of the precipitate; - the changed kinetics of precipitate formation and the elimination of the accompanying ions influence the morphological characteristics of the precipitate formed, being advantageous in certain fields of application; - separation based on the selective precipitate fcrma-tion may be realized; - by using the ion-exchange materials, the ions needed for the precipitate formation can be gained from cheaper raw materials or waste; - 2b - - the accompanying ions being bound in the solution by the ion-exchange material, may be utilized, v/hen regenerating the ion-exchange material; - solution and precipitate can be brought into contact in several stages, selective recirculation of the small-grained precipitate without mechanical organs becomes possible. C PI vι?o

Claims: - -'l - Claims : 1. Process for producing precipitates v/ith an increased grain size, v/ith improved sedimentation characteristics and/or higher purity from a liquid medium by means of a chemical reaction, c h a r a c t e r i z e d in that at least one of the components, the ions, forming the precipitate being slightly soluble in the liquid medium or inducing resp. promoting the chemical reaction betv/een the compounds being present in the solution, is introduced into the system bound to the ion-exchange material, v/hile this material, serving as an ion-exchange auxiliary phase, is brought into contact v/ith the solution containing the other component/s/ forming the precipitate, or the ion-exchange materials containing individually the components forming the precipitate are brought together in a liquid medium and preferably, by the partial re¬ circulation of the precipitate formed and/or by bringing repeatedly into contact with the ion-exchange auxiliar3 r phase and the solution, the grain size of the precipitate can be increased, simultaneous!; 7 - filtrability may be also improved. 2. Process as claimed in claim 1, c h a r a c ¬ e .i z e d in that the ion-exchange material is a cation-exchange or an anion-exchange material of natural or artificial origin, to be ised in a 33lid granular and/or gel and/or in a liquid state. 3. Process as claimed in claim 1 or 2, c h a ¬ r a c t e r i z e d in that as a liquid medium water and/or organic solvent/s/ are used, showing a poor solution pov/er in respect to the precipitate to be produced and the ion-exchange auxiliary phase, v/hile showing a good solution pov/er in respect to the other participant components. 4. Process as claimed in an of the claims 1 to 3, c h a r a c t e-r i z e d in that the solution, the ion-exchange auxiliary phase and the precipitate are brought into contact in one or more stages, v/hen operating in more stages, a part of the precipitate formed is recirculated betv/een the single stages and/or brought repeatedl; 7 " into contact with the ion-exchange auxiliary phase and the solution. 5. Process as claimed in an3/ of the claims 1 to 4, c h a r a c t e r i z e d in that the precipitate is formed of organic and/or inorganic components, ions and/or organic radicals-, out of which at least one is bound to the ion-exchange material. 6. Process as claimed in any of the claims 1 to 5, c h a r a c t e r i z e d in that in course of contacting the ion-exchange auxiliary phase, the solution and the precipitate dissipation heat transfer or heat extract is applied. 7. Process as claimed in any of the claims 1 to 6, c h a r a c t e r i z e d in that the mixture containing the ion-exchange auxlliarj-" phase, the solution and the precipitate is dissociated in components in a known manner, v/hile the ion-exchange material is regenerat and repeatedly used in the S r stem as an auxiliary ion- exchange phase. 8. Euipment for. producing precipitates v/ith an increased grain size, with improved sedimentation charac¬ teristics and/or of higher purity, c h a r a c t e r i z ¬ e in that v/ithin the apparatus-body /_/ there are one or more spaces /_/ having been separated by partitions /2/ l3 r in perpendicularl;-- to the material stream, v/hile on the bottom of the apparatus-body /!/ there are the a p ertures /6/ interconnecting said spaces, the stud /4/ protruding into the confining space /3/ is arranged expediently on the upper third of the partition-and the O W - ≥y - organs /7/ serving for the distribution of air or gas are connected to said stud, furtheron there is an aerolift /10/ v/ith the passage opening /__/ ' leading to the bottom of the last space and a further opening /15/ leading back into the upper part of the last space, in addition to these, there is a stud /14/ for the material discharge and an outlet /15/ for the air and gas. 9. Euipment as claimed in claim 8, c h a r a c- t e r i z e d in that the apparatus-body /_/ is narrowed dov/nv/ards or the lov/er part, preferab^ one third, isformed with a restricted cross-section /9/.

Inventors: CSOEVARI M, CSUKAS B, CZEGLE B, HORVATH A, STOCKER L
Applicants: CSOEVARI M, CSUKAS B, CZEGLE B, HORVATH A, NOVEX FOREIGN TRADE CO LTD, STOCKER L
Application year: 1981
Main classification: C01G1
IPC codes: B01D9, B01J19, B01J47, C01F5, C01F7, C01F11, C01G1, C01G3, C01G21, C01G45, C01G49