MXPA97010493A - Mixed particular material and parapreparing my process - Google Patents

Abstract

The present invention relates to a process for preparing a mixed particulate material comprising the steps of: providing a primary particulate material having a primary softening temperature; providing a particulate support material having a support softening temperature; providing a particulate binder material having a softening temperature that is lower than the primary softening temperature and the softening support temperature, mixing the primary material, the support material and the binder material in order to provide a mixture substantially uniform, and heating the mixture to a temperature greater than or equal to the softening temperature of the binder material and less than the primary softening temperature and the softening support temperature, whereby the binder material binds the primary material to the material of support with the f in to provide a particulate material mix

Description

MIXED MATERIAL IN PARTICLES AND PROCESS TO PREPARE THE SAME BACKGROUND OF THE INVENTION The invention relates to a process for preparing a mixed particulate material, especially a mixed particulate material for use in the treatment of aqueous solutions and vapor phase systems, wherein the mixed particulate material has an increased effectiveness and resistance to wear. Various materials and processes are well known in the art for treating aqueous solutions and vapor phase systems, particularly for the removal of unwanted heavy metals such as lead and the like. A process for the removal of heavy metals from aqueous systems is described in U.S. Patent No. 5,053,139, and a mixed ion exchange material for use in such processes is described in the U.S. Patent. No. 5,277,931. U.S. Patent No. 5,277,931 describes the preparation of a mixed ion exchange material wherein the porous particles are first sprayed with an aqueous base material and subsequently sprayed with a concentrated aqueous acid solution of a supply of suitable metal ions. It is said that this process for the preparation provides a mixed material without significant deposit within the pores of the support material and without encapsulating the particles of the porous material. In practice, it has been found that mixed materials formed in accordance with the teachings of the '931 patent are undesirably susceptible to wear. Specifically, large quantities of the primary material, which is typically the most expensive component of the final product, are lost during the packaging and transportation of the product. It is clear that there is a need for a mixed particulate material and a process for preparing same where the mixed particulate material is resistant to wear. Therefore, the primary object of the present invention is to provide a mixed particulate material and a process for preparing the same wherein the primary particles are substantially permanently bound to the carrier material, thereby significantly reducing or eliminating them. wear effects. A further object of the present invention is to provide a process for preparing a mixed particulate material which is useful in the treatment of aqueous solutions for the removal of heavy metals contained therein.

Still a further object of the present invention is to provide a mixed particulate material having excellent selectivity with respect to the removal of unwanted heavy metals contained in the aqueous solutions. Other objects and advantages of the present invention will appear hereinafter.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, the above objects and advantages are easily achieved. According to the invention, a process for preparing a mixed particulate material is provided, the process comprising the steps of providing a primary particulate material having a primary softening temperature; providing a particulate support material having a support softening temperature; providing a particulate binder material having a softening temperature that is lower than the primary softening temperature and the softening support temperature; mixing the primary material, the support material and the binder material to provide a substantially uniform mixture; and heating the mixture to a temperature greater than or equal to the softening temperature of the binder material and less than the primary softening temperature and the softening support temperature, whereby the binder material binds the primary material to the support material to provide a mixed particulate material. In accordance with the preferred embodiment of the invention, the primary particulate material has particle diameters of between about 1 to about 200 microns, the particulate support material has particle diameters of about 1 to about 250 microns and the binder material has particle diameters of between about 1 around 150 micrometers. According to another preferred embodiment of the invention, the process further includes the step of stirring the mixture during the heating step whereby the mixed particulate material remains in a loose non-continuous form. According to yet another preferred embodiment of the invention, the heating and stirring steps are carried out in the absence of increased pressure to reduce or substantially eliminate the deposit within the pores of the support material.

BRIEF DESCRIPTION OF THE DRAWINGS A detailed description of the preferred embodiments of the invention is presented below with reference to the accompanying drawings in which: Figure 1 is a drawing of a mixed material according to the prior art; and Figure 2 is a drawing of a mixed particulate material according to the invention.

DETAILED DESCRIPTION OF THE MODALITIES PREFERRED The invention relates to a process for preparing mixed particulate material, especially a mixed particulate material for use in the treatment of aqueous solutions and vapor phase systems for the removal of heavy metal contaminants found therein. According to the invention, a process for preparing mixed particulate materials having improved wear resistance is provided. According to the invention, there is provided a process wherein the primary particulate material is substantially permanently bonded to a particulate support material in a form that significantly reduces or eliminates the loss of the primary material due to wear. A binder material having a softening temperature lower than that of the primary and support materials is used in a heat process to provide the desired binder as will be described in detail below. A particular advantage of the present invention is that the desired mixed particulate material has increased wear resistance without substantial deposits within the pores of the primary and support materials and without encapsulating the particles of the primary material and the support material, with which provides a mixed material having desirable properties, for example to treat aqueous solutions for the removal of undesirable lead and other heavy metals. Referring now to Figures 1 and 2, a mixed particulate material according to the present invention will be further illustrated and compared to a conventional mixed material. Figure 1 shows a mixed material of the prior art having a primary material 10 directly applied to a support material 12. The mixed material of the prior art is typically of a mixed material prepared in accordance with a spray deposition technique such as is used in the aforementioned U.S. Patent 5,277,931. It has been found that the mixed material according to Figure 1 possesses an unsatisfactory wear resistance and, specifically, such mixed materials experience a great loss of primary material due to wear during packing, handling and use. This loss of primary material increases the cost of using such conventional materials. Referring now to Figure 2, the mixed particulate material according to the invention is generally illustrated at 14. In accordance with the invention, the material 14 comprises a particulate primary material 16, a particulate support material 18 and a binder material which binds the particles of the primary material 16 to the particles of the support material. The binder material 20 preferably agglutinates or adheres substantially permanently to the support material 18 and the primary material 16 to cover a relatively small portion of the surface area of the support material 18 such that the support material 18 is not masked by the binder material.

PRIMARY MATERIAL According to the invention, the primary material 16 can preferably be selected from the group consisting of inorganic hydrated metal oxides, amorphous metal silicates, zeolite and mixtures thereof, more preferably inorganic hydrated titanium oxides or silicates, oxides or silicates of inorganic hydrated tin and mixture thereof, and most preferably titanium silicate, tin silicate and mixtures thereof. The primary material of the present invention is preferably a material having a desired property in the final mixed product such as ion exchange capacity with a particular undesirable component or constituent of a medium to be treated with the mixed particulate material. Various primary materials are useful in accordance with the present invention for treating aqueous solutions for removing unwanted heavy metals such as lead., cadmium, zinc, chromium, arsenic, mercury and the like. Particularly preferred primary materials include titanium silicate and tin silicate for use in the preparation of a particulate material for the removal of lead. Of course, numerous other absorbent materials or means may be used according to the invention to provide a desired affinity for the removal of a particular undesired constituent. According to the invention, the primary material may be in the form of powder or particles of the same size. The primary material preferably has particle diameters of between about 1 to about 200 microns, and more preferably less than or equal to about 60 microns. Within the mentioned regime, the primary material preferably has a substantially uniform particle diameter.

SUPPORT MATERIAL The support material can be any of a wide variety of porous or non-porous materials and can also be selected to provide additional activity with respect to the removal of unwanted constituents in a medium to be treated. Examples of suitable support materials include carbon, especially activated carbon in granules; globules or glass bubbles; porous or non-porous volcanic media; pellets or plastic granules; plastic fibers; wood fibers; carbon fibers; ceramic media; refractory or non-refractory clay; diatomaceous earth; metal particles; ferromagnetic material; Silica gel; Magnetic stainless steel; organic fiber; cellulose fiber; acrylic fiber; silicon carbide and the like. A particularly preferred support material is activated carbon, especially activated carbon in granules. The support material preferably has particle diameters of from about 1 to about 2500 microns. Within said regime, the support material preferably has substantially uniform particle diameters which are substantially larger in size than the particle diameters of the primary material.

AGGLUTING MATERIAL The binder material can be any of a wide variety of materials including crystalline thermoplastic polymer, thermoplastic polymer, crystalline polymer and mixtures thereof. Preferably polyolefins, polyamides and mixtures thereof. Specific examples of preferred binder materials include polyethylene, polypropylene, ethylene vinylacetate, and mixtures thereof. The binder material can be provided in the form of particles having particle diameters of between about 1 to about 150 microns. Preferably, the binder particles have particle diameters less than or equal to about 30 microns. Within the aforementioned regime, the binder material preferably has a substantially uniform particle size. The relative sning temperature or vicat sning point of the binder material with respect to the primary and support materials is preferably provided according to the invention in such a way that the sning temperature of the binder material is significantly lower than that of the materials primary and support as will be discussed later. Typical binder materials have a sning temperature in the range of about 121 ° C (250 ° F) to about 204.4 ° C (400 ° F). For low temperature applications, the binder material preferably has a vicat sning point of between 65.5 ° C (150 ° F) to about 1 35 ° C (275 ° F), more preferably between about 76.6 ° C (1 70) ° F) at approximately 129.4 ° C (265 ° F).

PROCESS The process for preparing the mixed particulate material according to the invention will now be described. The mixed particulate material is provided in accordance with the invention by mixing the primary material, the support material and the binder material in selected amounts to provide a substantially uniform mixture, heating the mixture to a temperature sufficient to sn the binder material so that the particles of the binder material begin to lose shape and become substantially viscous to substantially adhere all of the adjacent particles of the primary and support materials, and either cooling the mixture or letting the mixture return to ambient temperature whereby the adhesion of the binder material between the primary material and the support material becomes substantially permanent, thereby providing a mixed particulate material that is especially resistant to wear losses, especially to primary material losses that occur with prepared materials convention onally. The primary materials, of support and binder preferably have softening temperatures such that the softening temperature of the binder material is significantly lower than the softening temperature of the primary and support materials. The softening temperature of the binder material is preferably sufficiently lower than the softening temperature of the primary material and the softening temperature of the support material so that the mixture can be heated to a temperature in the scale of the softening temperature of the binder material. without adversely affecting the primary and support materials. For low temperature applications, the vicat softening temperature of the binder material may suitably be between about 65.5 ° C (150 ° F) to about 135 ° C (275 ° F), preferably between about 76.6 ° C ( 1 70 ° F) at approximately 129.4 ° C (265 ° F). By providing a binder material having specific softening temperature characteristics, the heating step can be carried out to the point at which the binder material softens and begins to adhere to the primary and support materials as desired without adverse effects on the materials primary and support themselves. According to the invention, the primary, support and binder materials are preferably mixed in sufficient amounts such that the binder material is present in the mixture in an amount of at least about 5% by weight of the mixture, and preferably between about 5% to about 25% by weight of the mixture. Further in accordance with the invention, the mixing of the primary, support and binder materials is preferably stirred or otherwise maintained in motion during the heating step in order to provide a constant state of movement of the media during the stages of mixing and heating. Numerous apparatuses can be used to provide such constant movement such as a heated drum, a ribbon blender, a mixing machine or an extruder apparatus. This constant movement helps to avoid the formation of solid continuous structures different from those between the individual particles of the primary and support material, thereby providing a substantially non-continuous particulate end product as desired. Agitation or movement of the mixture is preferably continued beyond the heating step for at least a portion of time required for the hot mixture to cool or return to room temperature. In addition according to the invention, the mixing and heating steps are preferably carried out at atmospheric pressure in order to reduce the entry of materials such as the binder material into the pore spaces of the primary and support materials, especially the support material, whose pore spaces are believed to be particularly useful for providing the selectivity and desired activity of the final product, for example in the treatment of aqueous solutions for the removal of heavy metals. The mixing and heating steps according to the invention are therefore preferably carried out as close to atmospheric pressure as possible, ie in the absence of increased pressure, to reduce or prevent such deposition. According to the invention, the particles of the primary material, the support material and the binder can be provided in several different sizes within the aforementioned scales. It is preferable that the particles of the primary, support and binder material each have a substantially uniform particle size within the respective scale, and the support particles are preferably larger than the particles of the primary material. The appropriate dimension of the particulate materials can be achieved by grinding, sieving, grinding in a ball mill or any other method. An amount of each of the particles of the primary, support and binder material are thoroughly mixed in order to provide a substantially homogeneous and uniform mixture of the particles. As stated above, the binder particles are preferably provided to be present in the mixture in at least about 5% by weight of the mixture, preferably between about 5-25% by weight of the mixture. The particles of the primary material and of the support constitute the rest of the mixture, which can be modified according to the desired characteristics of the final product. Once the particles are thoroughly mixed, heat is applied to the mixture to raise the temperature of the mixture to a level which is higher than the softening temperature of the binder material and lower, preferably significantly lower, than the softening temperature of the primary support materials. It is preferred that the mixture is heated to a temperature that is close to the melting point of the binder when the binder material is a polyolefin or polyamide polymer group. More preferably, the heating step is carried out in order to maintain the temperature of the mixture within about 25 ° of the softening temperature of the agglutinating material so that the binder material is not softened to the point where it flows easily and masks the internal pores of the primary and support materials. During the heating step, the mixture is also preferably stirred according to the invention to avoid the formation of a continuous structure. As previously mentioned, the heating and stirring steps are preferably carried out in accordance with the present invention at atmospheric pressure in order to avoid significant deposition of the materials within the pore spaces of the primary and support materials. After the mixture has been sufficiently heated to provide the binder material in a substantially viscous state and in contact with the adjacent particles of the primary and support material, the mixture is allowed to return to room temperature, preferably while stirring is continued or mixed to additionally prevent the formation of continuous structures. During cooling and / or return to the ambient temperature of the mixture, the binder material solidifies and thereby substantially permanently bonds the particles of the primary material to the particles of the support material as desired. According to the invention, it has been found that the mixed particulate material formed according to the process of the present invention has significantly improved wear resistance compared to the material formulated according to the spray process of the United States patent. United No. 5,277,931. According to one embodiment of the invention, at least one of the primary material and the support material is preferably a ceramic ion exchange medium having a pore volume of desorption from about 0.03 to about 0.25 cubic centimeters per gram. so that the resulting mixed particulate material possesses desirable activity and regeneration characteristics. According to another embodiment of the invention, a particularly preferable mixed particulate material can be prepared using oxides or titanium silicates with polyolefin or polyamide binders, and with support particles composed of activated carbon in granules, ceramic media or refractory clays. According to yet another embodiment of the invention, one or both of the primary and carrier materials as set forth above may be a zeolite material, preferably an aluminosilicate such as class A zeolite and the like., which may be impregnated or otherwise provided with activated media or ions such as calcium, potassium, sodium and the like, or any other specific material having activity with respect to a desired contaminant to be treated with the mixed particulate material of the present invention. A wide range of zeolites are well known to those skilled in the art. Various types of zeolite having specific molar compositions and ratios may be useful according to the invention to provide a desired characteristic of the final product. It is understood that the invention is not limited to the illustrations described and shown herein, which are considered merely illustrative of the best ways of effecting the invention, and which are susceptible to modification of the shape, size, arrangement of the parts in details of the operation. The invention is directed rather to understand all those modifications that are within its spirit and scope as defined by the claims.

Claims (31)

1. CLAIMS 1 . A process for preparing a mixed particulate material comprising the steps of: providing a primary particulate material having a primary softening temperature; providing a particulate support material having a support softening temperature; providing a particulate binder material having a softening temperature that is lower than the primary softening temperature and the softening support temperature; mixing the primary material, the support material and the binder material in order to provide a substantially uniform mixture; and heating the mixture to a temperature greater than or equal to the softening temperature of the binder material and less than the primary softening temperature and the softening support temperature, whereby the binder material binds the primary material to the support material with In order to provide a mixed particulate material
2. 2. The process according to claim 1, characterized in that the primary particulate material has diameters of particles ranging from about 1 to about 200 microns, the particulate support material having particle diameters of between about 1 to about 2500 microns and The binder material has particle diameters of between about 1 to about 150 microns.
3. 3. The method according to claim 1, characterized in that the primary material has a substantially uniform primary particle diameter, and wherein the support material has a substantially uniform support particle diameter that is greater than the primary particle diameter.
4. 4. The method according to claim 1, characterized in that it further comprises the step of stirring the mixture during the heating step whereby the mixed particulate material remains non-continuous.
5. 5. The method according to claim 1, characterized in that the step of heating the mixture further comprises heating the mixture to atmospheric pressure.
6. 6. The method according to claim 1, characterized in that the step of providing the primary material comprises the step of providing a primary material selected from the group consisting of inorganic hydrated metal oxides, amorphous metal silicates, zeolite and mixtures thereof.
7. 7. The method according to claim 6, characterized in that the primary material is selected from the group consisting of inorganic hydrated titanium oxide, inorganic hydrated tin oxides and mixtures thereof.
8. 8. The method according to claim 6, characterized in that the primary material is selected from the group consisting of titanium silicate, tin silicate and mixtures thereof.
9. 9. The method according to claim 1, characterized in that the step of providing the support material comprises the step of providing a support material selected from the group consisting of porous support material, non-porous support material and mixtures thereof.
10. 10. The method according to claim 9, characterized in that the support material is activated carbon in granules. eleven .
11. The method in accordance with the claim 1, characterized in that at least one of the primary material and the support material is selected from the group consisting of titanium silicate, tin silicate and mixtures thereof.
12. 12. The method according to claim 1, characterized in that at least one of the primary material and the support material is a ceramic ion exchange medium having a pore volume of desorption from about 0.3 to about 0.25 cubic centimeters per gram. .
13. 13. The method according to claim 1, characterized in that the step of providing the particulate binder comprises the step of providing a binder material selected from the group consisting of crystalline thermoplastic polymer, thermoplastic polymer, crystalline polymer and mixtures thereof.
14. 14. The method according to claim 13, characterized in that the step of providing the particulate binder material comprises the step of providing a binder material selected from the group consisting of polyolefins, polyamides and mixtures thereof.
15. 15. The method according to claim 1, characterized in that the step of providing the particulate binder material comprises the step of providing a binder material selected from the group consisting of polyethylene, polypropylene, ethylene vinyl acetate and mixtures thereof.
16. 16. The method according to claim 1, characterized in that the softening temperature of the binder material is between about 65.5 ° C (150 ° F) to about 135 ° C (275 ° F).
17. 17. The method according to claim 1, characterized in that the softening temperature of the binder material is between about 121.1 ° C (250 ° F) to about 204.4 ° C (400 ° F).
18. 18. The method according to claim 1, characterized in that the mixing step further comprises the step of mixing the primary material, the support material and the binder material in such a way that the binder material is present in the mixture in an amount of at least about 5% by weight of the mixture.
19. 19. The method according to claim 18, characterized in that the binder material is present in the mixture in an amount of between about 5 to about 25% by weight of the mixture.
20. 20. The method according to claim 1, characterized in that the step of heating the mixture provides a hot mixture having a substantially viscous binder material in contact with the primary material and the support material, and further comprising the step of allowing the mixture The hot material returns to the ambient temperature whereby the viscous binder solidifies and binds the primary material to the support material. twenty-one .
21. The method according to claim 20, characterized in that it further comprises the step of stirring the hot mixture during the step of letting the hot mixture return to the ambient temperature, whereby the hot mixture remains in particles as the material Binder solidifies.
22. 22. A process for preparing a mixed particulate material for treating aqueous solutions and vapor phase systems for removing heavy metals, the mixed particulate material comprising an active particulate primary material for removing heavy metals and a particulate support material for supporting the primary material, and a binder material that binds the primary material to the support material, the process comprising the steps of: providing a primary material in particles having a primary softening temperature and particle diameters of between about 1 to about 200 micrometers; providing a particulate support material having a support softening temperature and having particle diameters of between about 1 to about 2500 microns; providing a binder material having a softening temperature that is less than the primary softening temperature and the softening support temperature and has particle diameters of between about to about 150 microns; mixing the primary material, the support material and the binder material in order to provide a substantially uniform mixture; and heating the mixture to a temperature greater than or equal to the softening temperature of the binder material and less than the primary softening temperature and the softening support temperature, whereby the binder material binds the primary material to the support material with In order to provide a mixed particulate material.
23. 23. A mixed particulate material for removing heavy metals from aqueous solutions comprising: a primary particulate material selected from the group consisting of inorganic hydrated metal oxides, amorphous metal silicates, zeolite and mixtures thereof; a particulate support material; and a particulate binder material adhered to the primary material and support material for bonding the primary material to the support material whereby the mixed particulate material has wear resistance.
24. 24. The mixed particulate material according to claim 23, characterized in that the primary material is selected from the group consisting of inorganic hydrated titanium oxide, inorganic hydrated tin oxides and mixtures thereof.
25. 25. The mixed particulate material according to claim 23, characterized in that the primary material is titanium silicate.
26. 26. The mixed particulate material according to claim 23, characterized in that the support material comprises activated carbon in granules.
27. 27. The mixed particulate material according to claim 23, characterized in that at least one of the primary material and the support material is a ceramic ion exchange medium having a pore volume of desorption from about 0.3 to about 0.25 cubic centimeters per gram.
28. 28. The mixed particulate material according to claim 23, characterized in that the step of providing the particulate binder material comprises the step of providing a binder material selected from the group consisting of crystalline thermoplastic polymer, thermoplastic polymer, crystalline polymer and mixture thereof. same.
29. 29. The mixed particulate material according to claim 23, characterized in that the step of providing the particulate binder material comprises the step of providing a binder material selected from the group consisting of polyolefins, polyamides and mixtures thereof.
30. 30. The binder material is selected from the group consisting of polyethylene, polypropylene, ethylene vinyl acetate and mixtures thereof.
31. 31. The mixed particulate material according to claim 23, characterized in that the mixed material has improved wear resistance compared to a material without such a binder.