WO1996039241A1

WO1996039241A1 - Porous carbon filter assembly for processing zirconium chloride

Info

Publication number: WO1996039241A1
Application number: PCT/US1996/008286
Authority: WO
Inventors: Robert S. Yih
Original assignee: Teledyne Industries, Inc.
Priority date: 1995-06-05
Filing date: 1996-06-05
Publication date: 1996-12-12

Abstract

A filter assembly is adapted for use with a plenum connected in fluid communication with a chlorinator reactor operative to reduce zircon sand into residue and chlorinator off gases of zirconium chloride and silicon chloride so that chlorinator off gases entrained with suspended particulate solids can be separated therefrom. The filter assembly includes a filter structure in a form of a plurality of filter elements and a support structure. Each of the filter elements is fabricated from a porous carbon material. The support structure includes a plate fabricated from a stiff, corrosion-resistant material and sized and adapted to be disposed and secured in an interior of the plenum. The plate has an array of holes formed therethrough. Each of the holes is sized and adapted to slidably receive a respective one of the filter elements. The support structure releasably retains the filter elements to the plate in a manner so that when the suspended particulate solids and chlorinator off gases are urged to move into the plenum from the chlorinator reactor, the chlorinator off gases migrate through the filter elements while the suspended particulate solids are unable to migrate therethrough. The present invention is also used in combination with a de-sublimation apparatus for condensing, i.e., de-subliming, a gaseous zirconium chloride into a solid zirconium chloride and a new and improved process for producing solid zirconium chloride from beach sand without the use of seed material.

Description

POROUS CARBON FILTER ASSEMBLY FOR PROCESSING ZIRCONIUM CHLORIDE

FIELD OF THE INVENTION The present invention relates to a process for separating zirconium chloride vapor from other materials present in a carbochlorination of zircon sand and, more particularly, to a filter assembly adapted for use with a chlorination reactor containing suspended particulate solids and gaseous compounds which are entrained therewith so that the gaseous or vapor phase compounds are separated from the particulate solids. More particularly, the present invention concerns a porous carbon filter assembly adapted for use with a plenum connected in fluid communication with a chlorinator reactor operative to reduce zircon sand into residue and chlorinator off gases of zirconium chloride and silicon chloride vapors so that chlorinator off gases can be separated effectively from the suspended particulate solids present in the reactor. The present invention is also used in combination with a de-sublimation apparatus connected downstream of and in fluid communication with the porous carbon filter assembly so that the gaseous zirconium chloride can condense, i.e., de-sublime, into a solid zirconium chloride.

BACKGROUND OF THE INVENTION Typically, zirconium metal is produced from solid zirconium chloride. One process for producing solid zirconium chloride from common beach sand is depicted in Figure 1. Feedstock 2 for this process is zircon sand 4 bearing the chemical name, zirconium silicon oxide (ZrSi0₄) , is mixed with carbon for use in a carbo-chlorination reaction zone. Feedstock 2 is placed in a standard feed hopper 4 and is then conveyed by a conveyor 6 into a conventional sand chlorinator reactor 8, which is typically a fluidized bed reactor. Feedstock 2 which is heated by induction coils 10 resting within the sand chlorinator reactor 8 on the fluidized bed so that chlorine gas (Cl₂) can percolate therethrough. Chlorine gas acts as an oxidizing agent that reacts with feedstock 2 to produce a residue and chlorinator off gases, particularly gaseous zirconium chloride vapor (ZrCl , and gaseous silicon chloride, SiCl₄. As the chlorinator off gases are produced in sand chlorinator reactor 8, they mix with fine suspended particulate solids that are introduced into sand chlorinator reactor 8 when the zircon sand is deposited thereinto. The chlorinator off gases rise within sand chlorinator 8 and are cooled by a cooler 12. The residue is discarded from the bottom of chlorinator reactor 8.

The mixture of the fine suspended particulate solids and the chlorinator off gases are transported to a primary filter plenum 14 that houses a filter assembly 16. Filter assembly 16 includes a plurality of filter elements 18, each of which are a cloth bag secured over a metal cage. Filter assembly 16 divides an interior of primary filter plenum 14 into an upstream plenum region 20 which is in fluid communication with sand chlorinator reactor 8 and a downstream plenum region 22 in fluid communication with upstream plenum region 20 through filter elements 18. A pressure differential between upstream plenum region 20 and downstream plenum region 22 can cause the chlorinator off gases as well as particles of carbon to migrate through cloth bag filter elements 18. Usually, as the chlorinator off gases migrate through cloth bag filter elements 18, the fine suspended particulate solids accumulate on the outer surfaces of cloth bag filter elements 18. However, once the chlorinator off gases and other material pass through cloth bag filter elements 18, the chlorinator off gases are now separated from the suspended particulate solids and are transported to a conventional primary condenser 20 having a cool condenser chamber 26 which is cooled by water circulating therethrough.

The chlorinator off gases are fed into a top center portion of primary condenser 24 so that the gaseous zirconium chloride can "de-sublime" into a solid zirconium chloride as it enters and moves through the cooled condenser chamber 26. The word "de-sublime" is utilized herein to describe a phase change that the gaseous zirconium chloride undergoes and is considered an opposite phase change to sublimation. Sublimation, of course, describes a situation whereby a compound or element changes from its solid phase directly to its gaseous phase without ever passing through its intermediate liquid phase. "De-sublimation" is hereby defined as a situation where a compound or element changes directly from its gaseous phase to its solid phase without ever passing through its intermediate liquid phase.

The cool condenser chamber 26 along with the particles of seed material causes the gaseous zirconium chloride to de-sublime into a solid zirconium chloride. The solid zirconium chloride having a density substantially greater than the remaining chlorinator off gases falls to a funnel-shaped bottom portion of primary condenser 24 where it is subsequently directed into a chloride receptacle 28.

Although most but not all of the gaseous zirconium chloride de-sublimes in primary condenser 20. As a result, the gaseous silicon chloride and the remaining gaseous zirconium chloride is directed to a secondary condenser 30. Therein, most of the remaining gaseous zirconium chloride is de-sublimed with the aid of a cool secondary condenser chamber 34 in the presence of particles of a seed material. Again, the solid zirconium chloride falls to a funnel-shaped bottom portion of secondary condenser 30 and is subsequently deposited into a second zirconium chloride receptacle 28'. The remaining gases pass through a secondary filter plenum 32 with a second filter assembly 16 ' as a gaseous effluent. At this stage, the gaseous effluent consists primarily of silicon chloride (SiCl₄) . Second filter assembly 16' includes a second filter elements 18' which are cloth bag filters connected to metal cages similar to filter elements 18 described above. Typically, however, second filter assembly 16' is identical in construction but smaller in size than filter assembly 16. Although it is not required that filter assembly 16 and second filter assembly 16' be identical in construction, economics and simplicity of maintenance support this arrangement.

One problem is encountered when the chlorinator off gases generated in the sand chlorinator reactor pass through cloth bag filter elements 18 of filter assembly 16. The fine suspended particulate solids accumulate on the outer surface of the filter elements. This particulate accumulation causes a pressure drop between upstream plenum region 20 and downstream plenum region 22. As a result, as particulate accumulation continues, it becomes increasingly difficult for the chlorinator off gases to migrate through the cloth bag filter elements and, thus, production rate continuously decreases. To rectify this problem, purging of the cloth bag filter elements is required. To purge, the process is discontinued and nitrogen under high pressure is introduced in the downstream plenum region of the filter assembly and directed toward the upstream plenum region thereby creating a back-flush effect. As the high pressure nitrogen migrates from the downstream plenum region and through the cloth bag filter elements, most of fine suspended particulate solids that had accumulated onto the outer surface of the cloth bag filter elements is liberated from the outer surface of the cloth bag filter elements. After purging, the process continues and the chlorinator off gases are, once again, more freely capable of migrating from the upstream plenum region through the cloth bag filter elements and into the downstream plenum region. Another problem associated with the process is that the cloth bag filter elements are generally not efficient for collecting dust particles. An empirical test of the recovered solid zirconium chloride reflects that large amounts of thorium particles are contained therein. Large amounts of thorium contained in the recovered solid zirconium chloride indicates poor dust collecting efficiency of the cloth bag filter elements. Additionally, cloth bag filter elements are fragile and tend to break down over relatively short periods of time. Although purging can help to reduce replacement costs of the cloth bag filters, the high pressure nitrogen stresses the cloth bag material in an opposite direction of the flow of the chlorinator off gases, thus shortening service life of these filter elements. With a shortened service life, maintenance costs increase because of the materials and labor associated with changing the cloth bag filter elements. For some plenum designs, the plenum must be cut open to gain access to the cloth bag filter elements. Furthermore, because of cloth material, temperatures in the chlorinator reactor must be maintained relatively low due to the risk that the cloth material might ignite on fire.

Extra care must also be taken when mounting the cloth bag filter elements onto their respective metal cages to prevent leakage of the fine suspended particulate solids into the downstream plenum region of the primary filter plenum. Occasionally, during processing, the cloth bag filter elements can tear or become unfastened from their metal cages. Leakage can then occur which results in contamination of the solid zirconium chloride recovered in the chloride receptacles.

Another problem with this prior art process is associated with the use of seed material. This process requires the use of seed material to act as a "physical catalyst" for the gaseous zirconium chloride to de-sublime into the solid zirconium chloride particulate. This catalytic effect is similar to "seeding" of clouds whereby the seed material provides a surface area upon which gases can condense. This seed material, although helpful for de-sublimation, must eventually be removed from the solid zirconium chloride and discarded as a waste product. When fine carbon is used as the seed material, the product is undesirably colored. Silica sand is also used as seed material. Both types of seed materials required internal baffles to insure that the vapor is in contact with the seed material a sufficient time for de-sublimation to occur. Up to as much as 7% by weight of the seed material must be used in the recovery of solid zirconium chloride. One processor of solid zirconium chloride reports that the discarded seed material used during this process accounts for approximately one-third of its total plant waste. With landfill space becoming rare, it would be desirable to eliminate the use of seed material to recover solid zirconium chloride. Unfortunately, without the use of seed material, the zirconium chloride forms as a light, fluffy solid which is less dense compared to solid zirconium chloride de-sublimed with seed material. The fluffy solid zirconium chloride tends to clog the funnel-shaped bottom portion of the condenser. As a result, production must be halted so that the condenser can be cleaned before operations can again be continued. Furthermore, the fluffy solid zirconium chloride tends to fill the chloride receptacles faster than the more dense zirconium chloride and, thus, extra labor is required for frequent exchanging of empty chloride receptacles for the full ones.

There is a need in the zirconium recovery industry for a new and improved process for the production of solid zirconium chloride. An improved process should include a new and improved filter assembly to filter chlorinator off gases from the suspended particulate solids. It would also be advantageous if this filter assembly would have superior performance characteristics such as improved dust collection efficiency, a longer service life, reduced maintenance requirements, and simple installation requirements. It would be further advantageous if the filter elements of this filter assembly be fabricated from a porous material having a much higher ignition temperature than cloth material. Further, it would be desirable to employ higher temperature processing so that high production efficiencies could be achieved. There is a need, therefore, to provide a porous filter assembly other than the bags currently employed which is suitable for use in high temperature, highly corrosive environments where an oxidizer reactor is employed to reduce a substance into oxidizer off gases or vapor. The industry also needs a porous filter assembly which minimizes the chances of leakage of the fine suspended particulate solids from the upstream plenum region of the filter plenum and into the downstream plenum region. It also would be advantageous if the porous filter assembly could operate to minimize the pressure drop between the upstream plenum region of the filter plenum and the downstream plenum region of the filter plenum. It would be further advantageous if the porous filter elements can resist accumulation of the fine suspended particulate solids on the filter elements.

There is another need in the production of zirconium to provide a filter assembly that can be used in combination with a de-sublimation apparatus that does not require the use of seed material. It would be advantageous if this de-sublimation apparatus can eliminate the use of seed material and still produce a solid, high density zirconium chloride product. There is a need in the industry to employ a filter assembly in combination with a de-sublimation apparatus that can reduce waste associated with the production of solid zirconium chloride. particularly by eliminating the need for seed material. It would be advantageous if the filter assembly and the de-sublimation apparatus can increase the production rate of solid zirconium chloride while simultaneously reducing shut-down time for cleaning filters or a clogged condenser. The present invention satisfies these needs and provides these advantages.

SUMMARY AND OBJECTS OF THE INVENTION It is an object of the present invention to provide a new and improved filter assembly adapted for use with a chlorinator reactor operative to reduce zircon sand into residue and chlorinator off gases of zirconium chloride vapors so that chlorinator off gases entrained with suspended particulate solids can be separated therefrom. It is another object of the present invention to provide a porous filter assembly having an improved dust collection efficiency, a longer service life and reduced maintenance requirements as compared to the prior art filters assemblies. It is yet another object of the present invention to provide a porous filter assembly that is simple to fabricate from porous carbon, easy to install and can operate in higher temperatures than currently employed.

A still further object of the present invention is to provide a porous carbon filter assembly which is versatile for use in high temperature, highly corrosive environments where an oxidizer reactor is employed to reduce a substance to oxidizer off gases and residue.

Yet another object of the present invention is to provide a porous carbon filter assembly which minimizes leakage of fine suspended particulate solids between an upstream plenum region of the filter plenum and a downstream plenum region of the filter plenum.

A further object of the present invention is to provide a porous carbon filter assembly which minimizes the pressure drop between the upstream plenum region of the filter assembly and the downstream plenum region of the filter plenum.

Yet still a further object of the present invention is to provide a porous carbon filter assembly that resists accumulation of the suspended particulate solids on outer surfaces of the porous carbon filter elements disposed in the downstream plenum region.

Another object of the present invention is to provide a porous carbon filter assembly that can be used in combination with a de-sublimation apparatus so that seed material for de-subliming gaseous zirconium chloride into a sufficiently dense, solid zirconium chloride can be eliminated. A still further object of the present invention is to provide a porous carbon filter assembly that can be used in combination with a de-sublimation apparatus so that waste produced as a result of making zirconium chloride can be reduced. Yet another object of the present invention is to provide a porous carbon filter assembly that can be used in combination with a de-sublimation apparatus so that the production rate of solid zirconium chloride can be increased compared to the prior art processes utilizing cloth bag filters and the introduction of seed material.

A still further object of the present invention is to provide a porous carbon filter assembly that can be used in combination with a de-sublimation apparatus whereby frequency of clogging of a condenser located downstream of the de-sublimation apparatus is decreased thereby reducing down time and cost of lost production due to increased maintenance associated with cleaning the clogged condenser.

Accordingly, a first exemplary embodiment of a filter assembly of the present invention and a second embodiment of a filter assembly used in combination with a de-sublimation apparatus are hereinafter described. The first exemplary embodiment of the filter assembly of the present invention is adapted for use with a plenum connected in fluid communication with an oxidizing reactor which contains suspended particulate solids and is operative for reducing a substance to gaseous compounds produced from the reduced substance and residue. The oxidizing reactor can be a conventional zircon sand chlorinator reactor. The gaseous compounds produced would, therefore, be zirconium chloride and silicon chloride.

In its broadest form, the filter assembly of the present invention includes a filter structure and a support structure. The filter structure is fabricated from a porous carbon material, preferably of a type that has a characteristic of being resistant to accumulation of the suspended particulate solids on the filter structure. The support structure is sized and adapted to be disposed and secured in an interior of the plenum to define an upstream plenum region in fluid communication with the oxidizing reactor and a downstream plenum region. The support structure is operative to releasably retain the filter structure thereon in a manner so that when the suspended particulate solids and gaseous compounds are urged as a result of a pressure differential within the oxidizing reactor and the downstream plenum region to move into the plenum from the oxidizing reactor, the gaseous compounds in the upstream plenum region are permitted to pass through the filter structure and into the downstream plenum region. Simultaneously therewith, the suspended particulate solids in the upstream plenum region are prevented from passing through the filter structure and into the downstream plenum region thereby separating the gaseous compounds from the suspended particulate solids.

The filter structure includes at least one filter element having an elongated body member and a flange although it is preferred that the filter structure includes a plurality of filter elements. The elongated body member extends longitudinally along and centrally about a longitudinal axis between a first end and an opposite second end. The flange extends radially from the longitudinal axis and around the first end which defines an opening into a bore centrally disposed about the longitudinal axis. The bore is formed into the body member and, preferably, terminates proximate to the second end. It is preferred that the body member and the bore are cylindrically shaped while the flange is preferably annularly shaped. Each filter element includes a collar connecting the flange and the body member.

The support structure includes a plate fabricated from a stiff, corrosion-resistant material. The plate has a flat first surface facing into the downstream plenum region and a flat second surface oriented opposite and parallel to the first surface and facing into the upstream plenum region. The plate also has at least one hole formed therethrough between the first and second surfaces which is sized and adapted to receive the filter element. The body member of the filter element is slidably received in the hole.

The support structure also includes at least one retaining device operative to releasably retain the filter element to the plate. The retaining device has a retainer element formed with an aperture therethrough and preferably a pair of fasteners. The retainer element is sized and adapted to extend across the first end and the flange of the filter element with the aperture sized and adapted to register with the bore of the filter element. The pair of fasteners are operative to releasably interconnect the retainer element and the plate when the retainer element is placed over and across the first end and the flange of the filter element with the aperture in registration with the bore.

Further, the support structure includes at least one annular support member being disposed concentrically about the hole and connected to the plate. The support member has an inner wall defining a frustoconically-shaped bore so that, when the filter element is slidably received into the hole, the inner wall and the outer collar surface are facially opposing each other. The filter assembly of the present invention preferably includes at least one of frustoconically-shaped ring seal, a gasket element and a weave spring element. The ring seal is sized and adapted to be interposed between the inner wall and the outer collar surface when the filter element is slidably received into the hole. The gasket element has a gasket opening formed therethrough and is sized and adapted to be interposed between the retainer element and the first end of the filter element with the gasket opening registering with the bore and the aperture when the retaining device releasably retains the filter element to the plate. The weave spring element has a centrally-disposed port formed therethrough and is sized and adapted to be interposed between the retainer element and the gasket element with the port in registration with the aperture and the gasket opening when the filter element is slidably received into the hole.

The second exemplary embodiment of the present invention is a porous carbon filter assembly adapted for use in combination with a de-sublimation apparatus. The de-sublimation apparatus is connected downstream of and in fluid communication with the porous carbon filter assembly and is used to de-sublime the gaseous zirconium chloride into a solid zirconium chloride while permitting other gaseous or vapor phase products to pass through. In its broadest form, the de-sublimation apparatus includes an inner cooler device, an outer cooler device, an inlet and an annular outlet. The inner cooler device includes an elongated tubular member having an outer cylindrical surface and extending along a vertical longitudinal axis. The inner cooler device is operative to cool the outer cylindrical surface. The outer cooler device has an inner cylindrical surface concentrically surrounding the outer cylindrical surface of the tubular member in a spaced apart relationship to define an annularly-shaped conduit therebetween. The outer cooler device is operative to cool the inner cylindrical surface.

The inlet enters into the annularly-shaped conduit and is disposed at an upper portion of the annularly-shaped conduit. The inlet is adapted to convey chlorinator off gases from the porous carbon filter assembly and into the upper portion of the annularly-shaped conduit. The annular outlet exits from the annularly-shaped conduit and is disposed at a bottom portion of the annularly-shaped conduit whereby the chlorinator off gases enter into the annularly-shaped conduit through the inlet and swirls downwardly therethrough while contacting the cooled outer cylindrical surface of the tubular member and the cooled inner cylindrical surface of the outer cooler device along the annularly-shaped conduit. This action causes a substantial amount of the gaseous zirconium chloride of the chlorinator off gases to de-sublime into solid zirconium chloride without the addition of seed material before the solid zirconium chloride and remaining chlorinator off gases and vapors exit the annularly-shaped conduit from the annular outlet.

Lastly, a new and improved process for producing a solid zirconium chloride from zircon sand is also described. The process comprises the step of conveying a zirconium silicon sand into a chlorinator reactor containing suspended particulate solids. The next step includes subjecting the zircon sand to gaseous chlorine at elevated temperatures in order to reduce the zircon sand to residue and chlorinator off gases of zirconium chloride and silicon chloride vapors. The next step then includes filtering the chlorinator off gases from the suspended particulate solids through a porous carbon filter assembly. The final step is de-subliming the filtered gaseous zirconium chloride into a solid zirconium chloride. It is preferred that this process include the de-sublimation apparatus as described above, maintained at a high enough temperature to permit desublimation of the zirconium chloride without appreciable contamination from solidified silicon tetrachloride.

These and other objects of the present invention will become more readily appreciated and understood from consideration of the following detailed description of the exemplary embodiments of the present invention when taken in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram of a prior art process for reducing zircon sand in a sand chlorinator reactor into a residue and chlorinator off gases of zirconium chloride and silicon chloride so that the gaseous zirconium chloride can subsequently be de-sublimed into a dense solidified zirconium chloride powder;

Figure 2 is a schematic diagram of a new and improved process of the present invention for reducing zircon sand in a sand chlorinator reactor into a residue and chlorinator off gases of zirconium chloride and silicon chloride which employs a filter assembly of the present invention so that the gaseous zirconium chloride can subsequently be de-sublimed into a solid zirconium chloride without using seed material; Figure 3 is a perspective view of a filter assembly of the present invention disposed within a primary filter plenum;

Figure 4 is a perspective view of a filter element of the filter assembly shown in Figure 3;

Figure 5 is a cross-sectional side view in elevation of the filter element taken along line 5-5 in Figure 4;

Figure 6 is a top plan view of the filter element shown in Figure 4; Figure 7 is a bottom plan view of the filter element shown in Figure 4;

Figure 8 is an enlarged cross-sectional view of one of the filter elements disposed in a support structure which is taken along line 8-8 in Figure 3; Figure 9 is a graph reflecting the improved dust collection efficiency of the filter assembly of the present invention that employs porous carbon filter elements as compared to prior art filter assemblies that employ cloth bag filter elements; Figure 10 is a side view in elevation of a de-sublimation apparatus cut away to show its internal structure as well as the fluids and the direction of fluid flow therewithin;

Figure 11 is a cross-sectional side view in elevation of the sublimation apparatus centrally mounted onto a top of a condenser showing its internal structure as well as the fluids and direction of fluid flow of fluids therewithin;

Figure 12 is a bottom plan view of the sublimation apparatus; and

Figure 13 is a cross-sectional view of the sublimation apparatus along line 13-13 in Figure 11.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

A filter assembly of the present invention is adapted for use in combination with a plenum connected in fluid communication with a chlorinator reactor that contains suspended particulate solids and is operative for reducing zircon sand into a residue and chlorinator off gases of zirconium chloride and silicon chloride. One of ordinary skill in the art would appreciate that although the detailed description of the exemplary embodiments of the invention related extraction and recovery of zirconium chloride from zircon sand, the filter assembly of the present invention could be used for other process applications. Thus, the filter assembly of the present invention could be utilized with any oxidizing reactor that contains suspended particulate solids and is operative for reducing a substance into a residue and oxidizer gases. Since the filter assembly of the present invention is fabricated from a porous carbon material, the filter assembly of the present invention is particularly useful in high temperature and/or highly corrosive environments. Furthermore, although the detailed description of the filter assembly of the present invention describes the filter assembly as having a plurality of filter elements, a skill artisan would appreciate that a single filter element could also be practiced without departing from the inventive concepts herein described.

A first exemplary embodiment of a filter assembly 40 of the present invention is generally introduced in Figures 2 - 8. With reference to Figure 2, filter assembly 40 is used in combination with primary filter plenum 14 connected in fluid communication with sand chlorinator reactor 8 which contains suspended particulate solids and is operative for reducing zircon sand, ZrSi0₄, into residue and chlorinator off gases. The chlorinator off gases are zirconium chloride, ZrCl₄, and silicon chloride, SiCl₄. Filter assembly 40 is adapted for use to separate the chlorinator off gases from the suspended particulate solids and includes a filter structure in a form of a plurality of filter elements 42 and a support structure 44. Each of filter elements 42 is fabricated from a porous carbon material. Although not by way of limitation, a porous carbon filter material was selected for the first embodiment of filter assembly 40 of the present invention with properties listed in Table 1 below.

Table 1 Bulk density (gr./cc) 0.909

Specific resistance 50.03 Flexural strength (psi) 952

789 Tensile strength (psi) 632

605

Compressive strength (psi) 1967 1971

Ap. porosity (%) 37.1

Permeability (darcys) 6.19

3.14

Young's Modulus (10° psi) 0.437 0.363

Thermal Conductivity 12.96

(room temperature) 10.81

1.222 1.683 Rt-1000° C 3.21

2.97 This porous carbon material is sold by Union Carbide under the trademark PC-100. In addition to other advantages and benefits, this porous carbon material exhibits a characteristic of being resistant to accumulation of the suspended particulate solids on the filter structure. As a result, filter elements 42 might be considered to be "self-cleaning".

As best shown in Figures 4 - 7, each of filter elements 42 has an elongated, cylindrically-shaped body member 46 and a flange 48. Body member 46 extends longitudinally along and centrally about a longitudinal axis "A" between a first end 50 and an opposite second end 52. Flange 48 is annularly-shaped and extends radially from longitudinal axis "A" and around first end 50. First end 50 defines an opening 54 into a cylindrically-shaped bore 56 which is centrally disposed about longitudinal axis "A". Bore 56 extends into body member 46 and terminates proximate to second end 52. In Figures 3 and 8, support structure 44 includes a plate 58 which is fabricated from a stiff, corrosion-resistant material such as stainless steel. Plate 58 is sized and adapted to be disposed and secured in an interior 60 of primary filter plenum 14 to define an upstream plenum region 62 in fluid communication with sand chlorinator reactor 8 and a downstream plenum region 64. Specifically, as shown in Figure 3, a support beam 65 is connected to primary filter plenum 14 in interior 60 and plate 58 is releasably fastened to support beam 65 by a conventional bolt and nut set 67, although other types of conventional fasteners could be used in lieu thereof. Plate 58 has a flat first surface 66 facing into downstream plenum region 64 and a flat second surface 68 oriented opposite and parallel to first surface 56 and facing into the upstream plenum region 62. An array of holes 70 are formed through plate 58 between first and second surfaces 66 and 68. Each of holes 70 is sized and adapted to slidably receive a respective one of filter elements 42.

Support structure 44 is operative to releasably retain filter elements 42 to plate 58 in a manner so that, when the suspended particulate solids and chlorinator off gases are urged as a result of a pressure differential between sand chlorinator reactor 8 and downstream plenum region 64 to move into primary filter plenum 14 from sand chlorinator reactor 8, the chlorinator off gases in upstream plenum region 62 are permitted to pass through the plurality of filter elements 42 and into downstream plenum region 64. Simultaneously therewith, the suspended particulate solids in upstream plenum region 62 are prevented from passing through filter elements 42 and into downstream plenum region 64 thereby separating the chlorinator off gases from the suspended particulate solids.

Each of filter elements 42 includes a collar 72 connecting flange 48 and body member 46. Collar 72 has an outer collar surface 74 tapering from an outer peripheral surface 78 of flange 48 towards an outer body surface 76 of body member 46. Outer collar surface 74 tapers at an angle "a", best shown in Figure 8, relative to longitudinal axis "A" between outer peripheral surface 78 of flange 48 and outer body surface 76 of body member 46. Although it is preferred that angle "a" is equal to 45°, angle "a" can be selected in a range of 35° and 55°.

Again with reference to Figures 3 and 8, support structure 44 includes a plurality of retaining devices 80 which are operative to releasably retain respective ones of filter elements 42 to plate 58. Each retaining device 80 has a retainer element 82 formed with an aperture 84 therethrough and a pair of fasteners 86. For the first embodiment of filter assembly 40 of the present invention, retainer element 82 is a rigid disk with a pair of fastener holes formed therethrough and the pair of fasteners 86 are conventional threaded bar and nut sets. One end of each of the threaded bars is advanced into plate 58 while an opposite end of each of the threaded bars matably engages respective ones of the nuts to secure retainer element 82 through its fastener holes over respective ones of filter elements 42 and to plate 58. Retainer element 82 is sized and adapted to extend across first end 50 and flange 48 of a respective one of filter elements 42. Aperture 84 is sized and adapted to register with bore 56 of respective ones of filter elements 42. A shroud 88 depends downwardly from retainer element 82 and radially equidistantly from longitudinal axis "A". Shroud 88 is sized to cover outer peripheral surface 78 of flange 48 when retainer element 82 is releasably interconnected to plate 58. The pair of fasteners 86 are operative to releasably interconnect respective ones of retainer elements 82 to plate 58 when retainer element 82 is placed over and across first end 50 and flange 48 of filter element 42 with aperture 84 in registration with bore 56 thereby releasably retaining filter element 42 to plate 58. Being able to releasably interconnect filter elements 42 to plate 58 affords easy and simple installation of individual ones of filter elements 42 to plate 58. As best shown in Figure 8, support structure 44 includes a plurality of annular support members 90. Each of support members 90 is disposed concentrically about a respective one of holes 70 and is connected to plate 58. Also, each of support members 90 has an inner wall 92 which defines a frustoconically-shaped bore 94. When respective ones of filter elements 42 are slidably received into respective ones of holes 70, inner wall 92 and outer collar surface 74 are facially opposing each other. Respective ones of inner walls taper at angle "b" relative to longitudinal axis "A" when respective ones of filter elements 42 are slidably received into respective holes 70 so that inner walls 92 and outer collar surfaces 74 can facially oppose each other. Although it is preferred that angle "b" equals 45°, angle "b" can be selected from a range between range of 35° and 55°. A skilled artisan would appreciate that in order for respective ones of inner walls 92 to facially opposed respective ones of outer collar surfaces 74, angle "a" and angle "b" are equal.

Filter assembly 40 of the present invention includes a plurality of frustoconically-shaped ring seals 94, gasket elements 96 and weave spring elements 98. Each ring seal 94 is sized and adapted to be interposed between respective ones of inner walls 92 and outer collar surfaces 74 when filter elements 42 are slidably received into respective ones of holes 70. Each gasket element 96 has a gasket opening 100 formed therethrough. Gasket element 96 is sized and adapted to be interposed between respective ones of retainer elements 82 and first ends 50 of filter elements 42. When interposed, gasket opening 100 registers with respective ones of bores 56 and apertures 84 when retaining devices 80 releasably retain respective ones of filter elements 42 to plate 58. Each weave spring element 98 has a centrally-disposed port 102 formed therethrough and is sized and adapted to be interposed between retainer element 82 and gasket element 96. When interposed, port 102 registers with aperture 84 and gasket opening 100 when respective ones of filter elements 42 are slidably received into respective ones of holes 70. Ring seals 94, gasket elements 96 and weave spring elements 98 are employed to seal filter assembly 40 in a manner so that leakage of suspended particulate solids from upstream plenum region to the downstream plenum region is minimized.

Filter assembly 40 of the present invention with porous carbon filter elements 42 was secured in interior 60 of primary filter plenum 14 and the process was implemented. Empirical tests were conducted to compare the dust collection efficiency of porous carbon filter elements with cloth bag filter elements. Thorium was measured in the solid zirconium chloride taken from chloride receptacles as the standard by which to determine dust collection efficiency. Results of these empirical tests are shown in Figure 9 and plotted as a function of temperature. In all instances, the porous carbon filter elements proved to be an improvement in dust collection efficiency as compared to cloth bag filters. As mentioned above, the porous carbon material employed for the present invention resists accumulation of the suspended particulate solids on outer surfaces of the porous carbon filter elements disposed in the downstream plenum region. Therefore, back-purging the filter elements does not occur as frequently compared to the prior art cloth filter elements. In one experiment, the porous carbon filter elements were in operation over three months before back-purging was implemented. In the prior art process, back-purging typically occurs every three days. Also, because of this resistance to accumulation of the suspended particulate solids on the outer surfaces of the porous carbon filter elements, the pressure drop between the upstream plenum region of the filter assembly and the downstream plenum region of the filter plenum is minimized when compared to the prior art. These benefits result in a longer service life and reduced maintenance requirements as compared to the prior art filters assemblies.

Furthermore, because the porous carbon filter material is a ceramic-like, it is extremely more durable than cloth bag filter elements. Installation of the porous carbon filters is also easier. The ceramic properties of the porous carbon filter elements allow the process to operate at higher temperatures. In fact, cooler 12 employed in the prior art process of Figure 1 is no longer needed for the new and improved process of Figure 2. Since there is now limited risk of fire, zirconium chloride production can be increased by using higher process temperatures. Again, because of the ceramic properties of the porous carbon filter elements, many harsh corrosive environments have little detrimental effects to the performance of the porous carbon filter elements. Although described for use with the production of solid zirconium chloride, the porous carbon filter elements could be used in other harsh environment processes that employ oxidizer reactors which might reduce a substance to oxidizer off gases and residue. With reference again to Figures 1 and 2, other structural differences between the prior art zirconium chloride production process (Figure l) and the new and improved process of the present invention (Figure 2) are different filter assemblies and the incorporation of a de-sublimation apparatus 210 shown in Figure 2. A major advantage of incorporating de-sublimation apparatus 210 into the production process is the elimination of seed material from the feed stock which is discussed in further detail below.

A second exemplary embodiment of a filter assembly 40 used in combination with a de-sublimation apparatus 210 is generally introduced in Figures 10 - 13. With reference to Figure 2, de-sublimation apparatus 210 is used in combination with primary filter plenum 14 that incorporates a porous carbon filter assembly 40 therein. Primary filter plenum 14 is connected downstream of and in fluid communication with sand chlorinator reactor 8 which contains suspended particulate solids and is operative for reducing zirconium silicon sand into a residue and chlorinator off gases of zirconium chloride and silicon chloride. De-sublimation apparatus 210 is connected downstream of and in fluid communication with porous carbon filter assembly 40 and is adapted for use to de-sublime the gaseous zirconium chloride into a solid zirconium chloride. Shown in Figures 10 - 13, de-sublimation apparatus 210 includes an inner cooler device 212, an outer cooler device 214, an inlet 216 and an annular outlet 218.

Inner cooler device 212 includes an elongated tubular member 220 having an outer cylindrical surface 222. Tubular member 220 extends along a vertical longitudinal axis "A'". Inner cooler device 212 is operative to cool outer cylindrical surface 222. Outer cooler device 214 has an inner cylindrical surface 224 concentrically surrounding outer cylindrical surface 222 of tubular member 220 in a spaced apart relationship to define an annularly-shaped conduit 226 therebetween. Outer cooler device 214 is operative to cool inner cylindrical surface 224.

Inlet 216 enters into annularly-shaped conduit 226 and is disposed at an upper portion 228 of annularly-shaped conduit 226 as shown in Figure 11. Inlet 216 is adapted to convey chlorinator off gases (represented as solid-line arrows) from porous carbon filter assembly 40 and into upper portion 228 of annularly-shaped conduit 226. Annular outlet 218 exits from annularly-shaped conduit 226 and is disposed at a bottom portion 230 of annularly-shaped conduit 226. Chlorinator off gases (solid-line arrows) enters into annularly-shaped conduit 226 through inlet 216 and swirls downwardly while contacting cooled outer cylindrical surface 222 of tubular member 220 and cooled inner cylindrical surface 224 of outer cooler device 214 along annularly-shaped conduit 226 thereby causing gaseous zirconium chloride of chlorinator off gases to de-sublime into solid zirconium chloride (represented by dots) before the solid zirconium chloride and remaining chlorinator off gases exit annularly-shaped conduit 226 from annular outlet 218. One of ordinary skill in the art would appreciate that the various arrow legends indicate different types of fluids and the direction in which the arrows point is the direction of the fluid flow for that particular fluid.

Annular outlet 218 is disposed at and defined by an outer bottom peripheral end 232 of tubular member 220 and an inner bottom peripheral end 234 of inner cylindrical surface 224 of outer cooler device 214. As best shown in Figure 13, inlet 216 is oriented in a manner whereby the chlorinator off gases (solid-line arrows) enter annularly-shaped conduit 226 transversely of vertical axis "A'" and tangentially to a radius "r" extending from vertical axis "A"¹. Although not by way of limitation, the chlorinator off gases enter annularly-shaped conduit 226 in this manner to cause it to swirl therewithin, thereby creating a cyclone effect around and through annularly-shaped conduit 226. It is theorized that this cyclone effect contributes to effective de-sublimation of the gaseous zirconium chloride.

Tubular member 220 includes an elongated cylindrically-shaped inner cooler chamber 234 formed thereinto. Inner cooler device 212 includes an inner cooler inlet 236 and an inner cooler outlet 238. Inner cooler inlet 236 is in fluid communication with inner cooler chamber 234 so that an inner cooling fluid (represented by double-dashed arrows) can be conveyed into inner cooler chamber 234. Although other conventional cooling fluids can be employed, inner cooling fluid is cool, forced air produced from any conventional source. Inner cooler outlet 238 is in fluid communication with inner cooler chamber 234 so that the inner cooling fluid can be conveyed from inner cooler chamber 234. Inner cooler inlet 236 and inner cooler outlet 238 are located at a top location 240 of inner cooler device 212. Further, inner cooler device 212 includes a tube 242 which is disposed within inner cooler chamber 234 and extends from and is in fluid communication with inner cooler inlet 236 toward a bottom location 244 of inner cooler chamber 234 as illustrated in Figures 10 and 11.

Outer cooler device 214 includes an outer cooler inlet 246, an outer cooler outlet 248 and an annularly-shaped outer cooler chamber 250 formed into outer cooler device 214. Outer cooler chamber 250 is in fluid communication with outer cooler inlet 246 so that an outer cooling fluid (represented by single-dashed arrows) can be conveyed into outer cooler chamber 250 and with outer cooler outlet 248 so that the outer cooling fluid can be conveyed from outer cooler chamber 250. Although other cooling fluids can be employed, outer cooling fluid is cool, forced air produced from any conventional source including the same one used to produce the inner cooling fluid. Outer cooler device 214 also includes a bulkhead 252 that depends downwardly from a top portion 254 of outer cooler device 214 and is disposed concentrically within outer cooler chamber 250 thereby dividing outer cooler chamber 250 into a first outer cooler chamber region 256 and a second outer cooler chamber region 258. Second outer cooler chamber region 258 is in fluid communication with first outer cooler chamber region 256 at a bottom portion 260 of outer cooler chamber 250. Outer cooler inlet 246 is in fluid communication with first outer cooler chamber region 256 so that the outer cooling fluid can be conveyed into outer cooling chamber 250. Outer cooler outlet 248 is in fluid communication with second outer cooler chamber region 258 so that the outer cooling fluid can be conveyed from outer cooling chamber 250. Outer cooler inlet 246 and outer cooler outlet 248 are located proximate top portion 254 of outer cooler device 214.

As best shown in Figures 2 and 11, de-sublimation apparatus 210 is adapted to mount to primary condenser 24. Primary condenser 24 with condenser chamber 26 formed therein is in downstream fluid communication with de-sublimation apparatus 210. At least a bottom section 262 of de-sublimation apparatus 210 extends vertically into condenser chamber 26. It is preferred that de-sublimation apparatus 210 is mounted to primary condenser 24 so that it is positioned in a top center location thereof.

Since some of the chlorinator off gases remains as gaseous zirconium chloride, the remaining chlorinator off gases are conveyed from primary condenser 24 to secondary condenser 30. As in the prior art process, some of the remaining gaseous zirconium chloride de-sublimes in secondary condenser chamber 34 of secondary condenser 30. The solid zirconium chloride is then transferred to a second chloride receptacle 28' while the chlorinator off gases remaining in secondary condenser 30 is transferred through a second filter assembly 42' of the present invention employing porous carbon filter elements 42' and discarded as an effluent, primarily in a form of silicon chloride, as shown.

Note in Figure 2, feedstock 2 for the production process is zircon sand, ZrSi0₄. When employing the de-sublimation apparatus, there is no longer a need to add seed material. Thus, seed material can now be eliminated from the production process of the present invention. A direct benefit of eliminating seed material from the production process is that waste which is naturally generated as a result of making zirconium chloride can be reduced. The filter assembly of the present invention requires less frequent back purging than cloth bag filter assemblies and the de-sublimation apparatus produces adequately dense solid zirconium chloride that tends to decrease the frequency of clogging of the primary condenser. As a result, production rate of zirconium chloride is increased and operational down time is decreased. Cost of lost production opportunity and maintenance for cleaning clogged condensers is reduced.

Furthermore, tests were conducted on the second exemplary embodiment of filter assembly 40 of the present invention used in combination with de-sublimation apparatus 210 to determine the optimum flow rate of chlorine in the sand chlorinator reactor 8 which could reduce clogging of primary condenser 24 with solid zirconium chloride. It was concluded that the optimum flow rate of chlorine was 600 pounds per hour compared to the prior art process of 500 pounds per hour. A skilled artisan would appreciate that a higher chlorine flow rate yields more solid zirconium chloride than a slower flow rate. Thus, not only is the solid zirconium chloride production increased but also the frequency of clogging of the primary condenser is reduced simultaneously. It follows that a new and improved process can be described for producing a solid zirconium chloride from an zirconium silicon sand. The first step of this new and improved process is conveying a zircon sand into a chlorinator reactor containing suspended particulate solids. Then, the next step is subjecting the zircon sand to gaseous chlorine in order to reduce the zircon sand to residue and chlorinator off gases of zirconium chloride and silicon chloride which become entrained with the suspended particulate solids in the chlorinator reactor. The next step is filtering the chlorinator off gases from the suspended particulate solids through a porous carbon filter assembly at high temperature. Finally, the last step is de-subliming the filtered gaseous zirconium chloride without the addition of seed material into a solid zirconium chloride at sufficiently high temperatures to prevent contamination of the particulate zirconium chloride product with silicon tetrachloride. It is preferred that this process include the de-sublimation apparatus as described above. Accordingly, the present invention has been described with some degree of particularity directed to the exemplary embodiments of the present invention. It should be appreciated, though, that the present invention is defined by the following claims construed in light of the prior art so that modifications or changes may be made to the exemplary embodiments of the present invention without departing from the inventive concepts contained herein.

Claims

I claim:

1. In combination with a plenum connected in fluid communication with an oxidizing reactor containing suspended particulate solids and operative for reducing a substance to gaseous compounds and residue, a filter assembly, comprising:

(a) a filter structure fabricated from a porous carbon material; and

(b) a support structure sized and adapted to be disposed and secured in an interior of the plenum to define an upstream plenum region in fluid communication with the oxidizing reactor and a downstream plenum region, said support structure operative to releasably retain said filter structure thereon in a manner so that when the suspended particulate solids and gaseous compounds are urged to move into the plenum from the oxidizing reactor, the gaseous compounds in the upstream plenum region are permitted to pass through said filter structure and into the downstream plenum region while the suspended particulate solids in the upstream plenum region are prevented from passing through said filter structure and into the downstream plenum region thereby separating the gaseous compounds from the suspended particulate solids.

2. A filter assembly according to claim 1 wherein said filter structure includes at least one filter element having an elongated body member extending longitudinally along and centrally about a longitudinal axis between a first end and an opposite second end and a flange extending radially from said longitudinal axis and around said first end, said first end defining an opening into a bore centrally disposed about said longitudinal axis and formed into said body member.

3. A filter assembly according to claim 2 wherein said bore terminates proximate to said second end.

4. A filter assembly according to claim 2 wherein said body member is cylindrically shaped.

5. A filter assembly according to claim 2 wherein said bore is cylindrically shaped.

6. A filter assembly according to claim 2 wherein said flange is annularly shaped.

7. A filter assembly according to claim 2 wherein said filter element includes a collar connecting said flange and said body member, said collar having an outer collar surface tapering from an outer peripheral surface of said flange towards an outer body surface of said body member.

8. A filter assembly according to claim 7 wherein said outer collar surface tapers at a 45 degree angle relative to said longitudinal axis between said outer peripheral surface of said flange and said outer body surface of said body member.

9. A filter assembly according to claim 2 wherein said support structure includes a plate fabricated from a stiff, corrosion-resistant material and having a flat first surface facing into the downstream plenum region and a flat second surface oriented opposite and parallel to said first surface and facing into the upstream plenum region, said plate having at least one hole formed therethrough between said first and second surfaces and sized and adapted to receive said filter element whereby said body member is slidably received in said hole so that said flange rests proximate to said first surface when said filter element is releasably retained to said plate.

10. A filter assembly according to claim 9 wherein said support structure includes at least one retaining device operative to releasably retain said filter element to said plate, said retaining device having a retainer element formed with an aperture therethrough and a pair of fasteners, said retainer element sized and adapted to extend across said first end and said flange of said filter element, said aperture sized and adapted to register with said bore of said filter element, said pair of fasteners operative to releasably interconnect said retainer element and said plate when said retainer element is placed over and across said first end and said flange of said filter element with said aperture in registration with said bore thereby releasably retaining said filter element to said plate.

11. A filter assembly according to claim 10 wherein said support structure includes at least one gasket member having a gasket opening formed therethrough, said gasket member sized and adapted to be interposed between said retainer element and said first end of said filter element with said gasket opening registering with said bore and said aperture when said retaining device releasably retains said filter element to said plate.

12. A filter assembly according to claim 1 wherein said porous carbon material has a characteristic of being resistant to accumulation of the suspended particulate solids on said filter structure.

13. In combination with a plenum connected in fluid communication with a chlorinator reactor containing suspended particulate solids and operative for reducing zircon sand into a residue and chlorinator off gases of zirconium chloride and silicon chloride, a filter assembly adapted for use to separate the chlorinator off gases from the suspended particulate solids, comprising:

(a) a plurality of filter elements, each of said filter elements fabricated from a porous carbon material and having an elongated, cylindrically-shaped body member extending longitudinally along and centrally about a longitudinal axis between a first end and an opposite second end and an annularly-shaped flange extending radially from said longitudinal axis and around said first end, said first end defining an opening into a cylindrically-shaped bore centrally disposed about said longitudinal axis and extending into said body member and terminating proximate to said second end; and

(b) a support structure including a plate fabricated from a stiff, corrosion-resistant material and sized and adapted to be disposed and secured in an interior of the plenum to define an upstream plenum region in fluid communication with the chlorinator reactor and a downstream plenum region, said plate having a flat first surface facing into the downstream plenum region, a flat second surface oriented opposite and parallel to said first surface and facing into the upstream plenum region and an array of holes formed therethrough between said first and second surfaces, each of said holes sized and adapted to slidably receive a respective one of said filter elements, said support structure operative to releasably retain said filter elements to said plate in a manner so that when the suspended particulate solids and chlorinator off gases are urged to move into the plenum from the chlorinator reactor, the chlorinator off gases in the upstream plenum region are permitted to pass through said plurality of filter elements and into the downstream plenum region while the suspended particulate solids in the upstream plenum region are prevented from passing through said filter elements and into the downstream plenum region thereby separating the chlorinator off gases from the suspended particulate solids.

14. A filter assembly according to claim 13 wherein said filter element includes a collar connecting said flange and said body member, said collar having an outer collar surface tapering from an outer peripheral surface of said flange towards an outer body surface of said body member.

15. A filter assembly according to claim 14 wherein said outer collar surface tapers at a 45 degree angle relative to said longitudinal axis between said outer peripheral surface of said flange and said outer body surface of said body member.

16. A filter assembly according to claim 14 wherein said support structure includes a plurality of retaining devices operative to releasably retain respective ones of said filter elements to said plate, each retaining device having a retainer element formed with an aperture therethrough and a pair of fasteners, each of said retainer elements sized and adapted to extend across said first end and said flange of respective ones of said filter elements, said aperture sized and adapted to register with said bore of respective ones of said filter elements, said pair of fasteners operative to releasably interconnect said retainer element and said plate when said retainer element is placed over and across said first end and said flange of said filter element with said aperture in registration with said bore thereby releasably retaining said filter element to said plate.

17. A filter assembly according to claim 16 including a plurality of gasket elements, each gasket elements having a gasket opening formed therethrough, said gasket element sized and adapted to be interposed between respective ones of said retainer elements and said first ends of said filter elements with said gasket opening registering with respective ones of said bores and said apertures when said retaining devices releasably retain respective ones of said filter elements to said plate.

18. A filter assembly according to claim 17 wherein said support structure includes a plurality of annular support members, each of said support members being disposed concentrically about a respective one of said holes and connected to said plate, each of said support members having an inner wall defining a frustoconically-shaped bore whereby, when respective ones of said filter elements are slidably received into respective ones of said holes, said inner wall and said outer collar surface are facially opposing each other.

19. A filter assembly according to claim 18 wherein respective ones of said inner walls taper at a 45 degree angle relative to said longitudinal axis when respective ones of said filter elements are slidably received into respective ones of said holes.

20. A filter assembly according to claim 18 including a plurality of frustoconically-shaped ring seals, each ring seal sized and adapted to be interposed between respective ones of said inner walls and said outer collar surfaces when said filter elements are slidably received into respective ones of said holes.

21. A filter assembly according to claim 20 includes a plurality of weave spring elements, each weave spring element having a centrally-disposed port formed therethrough and sized and adapted to be interposed between said retainer element and said gasket member with said port in registration with said aperture and said gasket opening when respective ones of said filter elements are slidably received into respective ones of said holes.

22. In combination with a plenum incorporating a porous carbon filter assembly therein, the plenum connected downstream of and in fluid communication with a chlorinator reactor containing suspended particulate solids and operative for reducing zircon sand into a residue and chlorinator off gases of zirconium chloride and silicon chloride, a de-sublimation apparatus connected downstream of and in fluid communication with the porous carbon filter assembly and adapted for use to de-sublime the gaseous zirconium chloride into a solid zirconium chloride, comprising: (a) an inner cooler device including an elongated tubular member having an outer cylindrical surface and extending along a vertical longitudinal axis, said inner cooler device operative to cool said outer cylindrical surface;

(b) an outer cooler device having an inner cylindrical surface concentrically surrounding said outer cylindrical surface of said tubular member in a spaced apart relationship to define an annularly-shaped conduit therebetween, said outer cooler device operative to cool said inner cylindrical surface;

(c) an inlet entering into said annularly-shaped conduit and disposed at an upper portion of said annularly-shaped conduit, said inlet adapted to convey chlorinator off gas from the porous carbon filter assembly and into said upper portion of said annularly-shaped conduit; and

(d) an annular outlet exiting from said annularly-shaped conduit and disposed at a bottom portion of said annularly-shaped conduit whereby the chlorinator off gases enter into said annularly-shaped conduit through said inlet and swirls downwardly while contacting said cooled outer cylindrical surface of said tubular member and said cooled inner cylindrical surface of said outer cooler device along said annularly-shaped conduit thereby causing the gaseous zirconium chloride of the chlorinator off gases to de-sublime into solid zirconium chloride before the solid zirconium chloride and remaining chlorinator off gases exit said annularly-shaped conduit from said annular outlet.

23. A de-sublimation apparatus according to claim 22 wherein said annular outlet is disposed at and defined by an outer bottom peripheral end of said tubular member and an inner bottom peripheral end of said inner cylindrical surface of said outer cooler device.

24. A de-sublimation apparatus according to claim 22 wherein said inlet is oriented in a manner whereby the chlorinator off gases enter said annularly-shaped conduit transversely of said vertical axis.

25. A de-sublimation apparatus according to claim 22 wherein said tubular member includes an elongated cylindrically-shaped inner cooler chamber formed thereinto and wherein said inner cooler device includes an inner cooler inlet in fluid communication with said inner cooler chamber so that an inner cooling fluid can be conveyed into said inner cooler chamber and an inner cooler outlet in fluid communication with said inner cooler chamber so that the inner cooling fluid can be conveyed from said inner cooler chamber.

26. A de-sublimation apparatus according to claim 25 wherein said inner cooler device includes a tube disposed within said inner cooler chamber and extending from and in fluid communication with said inner cooler inlet toward a bottom of said inner cooler chamber.

27. A de-sublimation apparatus according to claim 25 wherein said inner cooler inlet and said inner cooler outlet are located at a top location of said inner cooler device.

28. A de-sublimation apparatus according to claim 22 wherein said outer cooler device includes an outer cooler inlet, an outer cooler outlet and an outer cooler chamber formed into said outer cooler device, said outer cooler chamber being in fluid communication with said outer cooler inlet so that an outer cooling fluid can be conveyed into said outer cooler chamber and with said outer cooler outlet so that the outer cooling fluid can be conveyed from said outer cooler chamber.

29. A de-sublimation apparatus according to claim 28 wherein said outer cooler device includes a bulkhead depending downwardly from a top portion of said outer cooler device and disposed concentrically within said outer cooler chamber thereby dividing said outer cooler chamber into a first outer cooler chamber region and a second outer cooler chamber region in fluid communication with said first outer cooler chamber region at a bottom portion of said outer cooler chamber, said outer cooler inlet being in fluid communication with said first outer cooler chamber region so that the outer cooling fluid can be conveyed into said outer cooler chamber and said outer cooler outlet being in fluid communication with said second outer cooler chamber region so that the outer cooling fluid can be conveyed from said outer cooler chamber.

30. A de-sublimation apparatus according to claim 29 wherein said outer cooler inlet and said outer cooler outlet are located proximate said top portion of said outer cooler device.

31. A de-sublimation apparatus according to claim 22 wherein said de-sublimation apparatus is adapted to mount to a condenser being in downstream fluid communication with said de-sublimation apparatus and having a condenser chamber formed therein whereby at least a bottom section of said de-sublimation apparatus extends vertically into said condenser chamber.

32. A process for producing a solid zirconium chloride from a zircon sand, comprising the steps of:

(a) conveying a zirconium silicon sand into a chlorinator reactor containing suspended particulate solids;

(b) subjecting the zirconium silicon sand to gaseous chlorine at a sufficiently high enough temperature in order to reduce the zirconium silicon sand to residue and chlorinator off gases of zirconium chloride and silicon chloride, said chlorinator off gases becoming entrained with the suspended particulate solids; (c) filtering the chlorinator off gases from the suspended particulate solids through a porous carbon filter assembly; and

(d) de-subliming the filtered gaseous zirconium chloride into a solid zirconium chloride.

33. A process according to claim 32 wherein step (d) includes de-subliming the filtered gaseous zirconium chloride in a de-sublimation apparatus comprising:

(i) an inner cooler device including an elongated tubular member having an outer cylindrical surface and extending along a vertical longitudinal axis, said inner cooler device operative to cool said outer cylindrical surface;

(ii) an outer cooler device having an inner cylindrical surface concentrically surrounding said outer cylindrical surface of said tubular member in a spaced apart relationship to define an annularly-shaped conduit therebetween, said outer cooler device operative to cool said inner cylindrical surface;

(iii) an inlet entering into said annularly-shaped conduit and disposed at an upper portion of said annularly-shaped conduit, said inlet adapted to convey chlorinator off gas from the porous carbon filter assembly and into said upper portion of said annularly-shaped conduit; and

(iv) an annular outlet exiting from said annularly-shaped conduit and disposed at a bottom portion of said annularly-shaped conduit whereby the gaseous zirconium chloride enters into said annularly-shaped conduit at a high enough temperature to be maintained in the vapor state, through said inlet and swirls downwardly while contacting said cooled outer cylindrical surface of said tubular member and said cooled inner cylindrical surface of said outer cooler device along said annularly-shaped conduit thereby causing the gaseous zirconium chloride to de-sublime into solid zirconium chloride before the solid zirconium chloride and remaining uncondensed chlorinator off gases exit said annularly-shaped conduit from said annular outlet.