WO1999020582A1

WO1999020582A1 - System and method of producing pure elements from parent compounds

Info

Publication number: WO1999020582A1
Application number: PCT/US1998/022423
Authority: WO
Original assignee: Birken, Stephen, M.
Priority date: 1997-10-23
Filing date: 1998-10-23
Publication date: 1999-04-29
Also published as: AU1116099A

Abstract

Pure elements are produced from their parent compounds by exposing the compounds to high source of energy (16) to disassociate the constituents of the compound into gaseous form. The gaseous elements are then collected in a collection device (17) to thereby produce pure elements from the compounds.

Description

SYSTEM AND METHOD OF PRODUCING PURE ELEMENTS FROM PARENT

COMPOUNDS

FIELD OF INVENTION The present invention relates to producing elements from parent compounds. In particular, elements such as pure metals are produced from compounds such as oxides using high energy disassociation techniques.

BACKGROUND OF THE INVENTION In order to obtain pure metals, for example from naturally occurring compounds, the prior art system and method rely on chemical techniques that are usually tedious and expensive. For example, in order to obtain pure titanium ("Ti") from naturally occurring rutile ("TiO "), the rutile is processed using chemical techniques as follows. First, a rutile sample is placed in a furnace and added with chlorine at elevated temperatures to convert TiO into titanium tetrachloride ("TiCl "). TiCl₄ is then precipitated back out into TiO₂ using oxygen to form precipitate TiO₂ as opposed to rutile TiO₂. Precipitate TiO₂ is typically used as white pigment for paints and coated paper as well as other well known products.

In order to make titanium metal, TiCl₄ is typically bled off during the formation of precipitate TiO into another furnace. TiCl is then reacted with pure magnesium at which point titanium ("Ti") sponge is produced in conjunction with by-products such as magnesium chloride ("MgCl₂"). The resulting Ti is called a sponge because the Ti material is bubbly and full of holes resembling a sponge-like substance. The Ti sponge is further processed in a series of furnaces to produce Ti ingots which are then sold on the market. The MgCl by-product has no real market value. Therefore, further chemical procedures are typically performed to salvage as much of the magnesium as possible for reuse.

As described above, the prior art procedure produces large amounts of unwanted and unnecessary chemical by-products in order to produce pure titanium from its natural source, rutile. Furthermore, the chemical processing of the prior art is very expensive, driving up prices for the resulting metals. What is needed is a more efficient system and method for producing pure metals without producing unwanted and unnecessary chemical by-products while keeping production costs down.

SUMMARY OF THE INVENTION The present invention overcomes the above mentioned deficiencies of the prior art system and method by producing elements, such as pure metals, from compounds by using disassociation techniques. Specifically, the present invention is directed towards producing pure metals by dissociating the element from its naturally occurring compound by subjecting the source to high amounts of energy in a short amount of time.

BRIEF DESCRIPTION OF DRAWINGS The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description: Figure 1 shows a block diagram of a system according to the present invention.

Figure 2 shows a first embodiment of the present invention. Figure 3 shows a second embodiment of the present invention. Figure 4 shows a third embodiment of the present invention. Figure 5 shows a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, pure elements, such as titanium, is produced from its parent compound by way of high energy disassociation. As shown in Figure 1 , system 10 of the present invention includes a process chamber 12, an environmental adjustment unit 13, a carrier 14, a high energy source 16, and a collection device 17. A compound to be processed is placed in a carrier 14 and placed in process chamber 12.

Environmental adjustment unit 13 adjusts the environmental conditions in process chamber 12. For example, environmental adjustment unit 13 can create an under pressurized condition such as a vacuum by pumping out the air in chamber 12 or create an induced gaseous environment by introducing gases such as chlorine into the chamber. Preferably, the under pressurized condition is under 1 atmospheric pressure. Besides the benefit of suppressing electrical arcing in the chamber, induced gaseous conditions also facilitate desired chemical reactions in the chamber between the introduced gas and the disassociated elements to create other desired compounds.

High energy source 16 supplies high energy to the compound in carrier 14 such that the compound undergoes disassociation. The disassociated gases are then collected in collection device 17 where the condensing metals are collected.

Figures 2-5 show different embodiments of high energy source 16 that may be used as the high energy source capable of producing high amounts of energy in a short amount of time. By way of example only, the first embodiment of the present invention as shown in Figure 2 uses a pair of electrodes 18 to deliver the energy to the material in carrier 14 by way of an electrical arc. Figure 3 shows a second embodiment using laser 20. Figure 4 shows a third embodiment using plasma torch 22, such as an induction coupled plasmas spectroscopy, for example. Figure 5 shows a fourth embodiment using a millimeter wave source such as a gyrotron, for example, to provide the necessary energy to the material in carrier 14. A millimeter wave is usually defined by a wave greater than 24 GHz. Other appropriate high energy sources may be used, such as a particle beam (not shown), without departing from the scope of the present invention.

The amount of energy to be delivered to a sample is determined by the bond energies of the molecules present in the sample compound. That is to say, the energy needed to disassociate the sample must be greater than the heat of atomization of the sample compound. For example, the energy needed to disassociate titanium from oxygen in TiO₂ is approximately 13eV (electron-volts). The bond energy information is readily available in chemistry reference books. In general terms, the heating rate of materials is given by the equation: AU = mCAT where AU is the energy absorbed by the material, m is the mass of the material, C is the specific heat and AT is the temperature rise.

Furthermore, it is critical that the energy needed to initiate disassociation of the sample be delivered to the sample in a relatively short amount of time. According to Boltzmann's law, the time relationship of energy shed by a sample compound is approximately t , where t is time. Therefore, the energy supplied to the material is high enough to break the molecular bonds but is delivered in a short amount of time so that the material do not dissipate the already received energy, thus preventing the sample from disassociating. The amount of energy and the time necessary to disassociate the atoms vary based on the bond energies of the molecules present in the compound as well as the amount of the sample compound.

Once the energy is delivered to the sample, the energy level is maintained long enough for the disassociation to occur. As the constituents of the sample disassociate under the influence of the energy, each of the constituents form segregated zones based on its internal energy and the energy distribution of the energy beam. More specifically, the imparted energy is distributed within the process chamber resembling a Gaussian distribution, i.e., the energy density is the highest in the center of the energy beam and tapers off away from the center in a bell-shape manner. Therefore, lighter constituents, i.e., with lower internal energy levels, congregate towards the outer radius from the imparted energy beam while heavier constituents, i.e., with higher energy levels, congregate toward the center of the energy beam. Consequently, it is possible to segregate the individual constituents of a sample into these segregated zones when disassociated using the techniques of the present invention.

EXAMPLE OF AN EMBODIMENT OF THE PRESENT INVENTION

In order to demonstrate the technique and apparatus of the present invention by way of example only, the following experiment has been performed referring to Figure 5.

Experiments were carried out on the heating of materials with a 200 kW, 110 GHz gyrotron at Communication and Power Industries (CPI) in Palo Alto, CA. The 110 GHz gyrotron used is the S/N4 tube which could be operated at power levels up to 400 kW in pulse lengths of up to 6 seconds or up to 100 kW in continuous

(CW) operation. The output from the gyrotron was a Gaussian-like beam in free space.

It was directed by an "elbow" mirror up through a first load section, a sample chamber, and into a second load section. The sample chamber was set up as a vacuum cross with four horizontal ports and two vertical ports. The vertical ports had boron nitride (BN) windows. The horizontal ports had an infrared (IR) camera for measuring the sample temperature, a visible CCD camera, a pumping port and a spare port. VCR systems and a computer were used to monitor the cameras. The sample temperature rise could be observed with the IR camera. Samples at high temperatures could also be monitored through their light emission by the CCD camera.

The sample chamber was evacuated by a mechanical pump system with a cold trap and a zeolite filter built at RPI. The vacuum line contained a leak valve which connected to a residual gas analyzer (RGA) for monitoring the gases evolved from the sample chamber during heating. The sample was held in the center of the chamber in a BN crucible which was a half-sphere.

Heating experiments were conducted sequentially on samples of high purity silica (called experiment 1), low purity silica (experiment 3), rutile (experiment 4), chalcopyrite (experiment 6), oil shale (experiment 7) and ilmenite (experiment 5). Microwave power was applied in one of two methods: average power and long pulse power. In the average power method, the gyrotron was operated at a power level of about 50 to 100 kW in pulses of about 0.5 to 3.0 milliseconds and at repetition rates of 1 to 60 Hz. The sample temperature was monitored on the IR camera and the evolved gases were monitored with the RGA. All samples were initially heated (that is, preheated) by this method. The aim was to eliminate any water or other low vapor pressure contaminants by a slow heating process. Samples of chalcopyrite, oil shale and ilmenite were brought to high temperature by this method. In long pulse heating, pulses of up to 2 seconds were applied to the sample to bring it to high temperature. The silica and rutile samples were heated by the long pulse method after a period of average power heating. All samples were easily raised to very high temperature, to the point where visible light emission was observed. This verified that high frequency microwaves would couple to the materials including low loss materials like silica. The samples were collected and stored in containers for later chemical analysis. The list of seven experiments given below was the original program plan for the experiments at CPI. All experiments consisted of irradiating (heating) samples with 110 GHz radio frequency

(RF) radiation. The microwave beam was to be set at 200 kW power level focused down to a spot size of about 1.8 inches. Samples were held in a boron nitride (BN) crucible located in a vacuum chamber. The chamber had BN windows for the entrance and exit of the microwave beam. Other ports on the chamber were for pumping, for an infrared camera and for a visible camera. The microwave power were held at a value of up to about 200 kW but the pulse length were varied from a few milliseconds up to several seconds.

Diagnostics included use of the infrared camera to monitor the temperature rise of the samples. The visible camera allows very high temperatures to be monitored as the sample emits visible radiation above about 1000 degrees C. A residual gas analyzer (RGA) was used on the vacuum port to monitor the gases evolved from the sample. Zeolite filters were used on the pump and were saved for later analysis of evolved material. Material frozen on the cryotrap of the vacuum system were also saved for later analysis.

Experiment 1 : Baseline Experiment(s)

The first experiment was a sample of standard silica. It has a coarse mesh size in hopes of avoiding any problems with the material blowing about within the chamber during pump down and back to atmosphere operations.

The objective was to monitor the temperature rise of the sample with the cameras. This temperature rise should agree reasonably well with theoretical predictions. Material was also collected at the cryo-trap and at the zeolite filters.

A separate baseline experiment was considered. It was a sample of silica to which has been added some graphite to make an absorbing sample. Differences between this sample and the pure sample was of interest.

Experiment 2: High purity silica (B13. B16)

Ultra pure samples of silica were heated. These samples come in 30 gram bottles. Each sample had three bottles. There were three samples for a total of nine bottles. After irradiation with the microwave beam, these samples were sent out for ICP analysis. The objective was to see if the material can be increased in purity by irradiation. Experiment 3: Low purity silica

Samples of lower purity silica were heated. Again, the objective was to see if the material can be increased in purity by irradiation.

Experiment 4: Rutile

Rutile (TiO₂) was heated. The material was 28 mesh size. The approximate analysis was 92% TiO₂, 1 to 2 % silica and about 5% Fe₂O . The rutile initially looked black due to the impurity content. After heating, it was expected to turn gray. The objective was to eliminate the Fe₂O₃ but save the TiO₂. If, after heating, the material still appeared black, it was to be heated further until it vaporized.

Experiment 5: Ilmenite

The ilmenite sample was a 320 mesh size like flour in consistency. It was about 60% TiO₂ and 35% Fe₂O₃. The objective was to separate the Fe₂O₃ from the TiO₂; the latter is the desired product. As the sample was heated it was hoped that the Fe₂O₃ will evolve first from the sample. If that does not happen from the solid sample, the sample was to continue to be heated until it vaporized. It may be that the gaseous phase will naturally evolve as Fe O₃ and TiO₂. These could be separated in the gaseous phase chemically. One advantage of the microwave heating at high frequencies may be the faster rate at which the sample can be heated to vaporization.

Experiment 6: Chalcopyrite

Chalcopyrite contains Cu, Fe and S. It also has trace amounts of Au and Ag. Upon being heated, it was expected that the sulfur would evolve first. The remaining material would be Cu and Fe. If we could then heat further and eliminate the Fe, we would be left mainly with Cu. This residual material would be valuable. The higher the Cu content, the better. The particle sizes would be -18 Mesh (about 1 mm and under) or +18 Mesh (about 1 mm and over). Experiment 7: Oil Shale

The oil shale material was a "greasy rock" or wax paraffin. The objective was to get the organics out. The organics have value as a heating oil. The remaining material would be CaCO (calcium carbonate) and silica (SiO₂). Up to 70 or 80% of the material could be eliminated as organics.

The experimental system consisted of the following major pieces of equipment:

1. High power gyrotron. This is a 110 GHz gyrotron, serial number S N4, which can operate at 100 kW in true CW operation or at 400 kW for pulses of up to about 10 seconds. It is also capable of operating at 1 MW of output power for up to 0.8 second. Operation at these power levels is conducted under conditions of no reflected power. If power is reflected back into the gyrotron, it must be operated at lower power levels. The gyrotron is operated in a shielded lead house at CPI with diagnostics, water cooling, control system and power supply. These will not be described here. The gyrotron is described in a published article: "Long-Pulse and CW tests of a 110 GHz gyrotron with an internal quasi-optical converter," by Kevin Felch et al., IEEE Transactions on Plasma Science, Vol. 24, No. 3, June, 1996 pages 558-569, herein incorporated by reference.

2. CPI Microwave Load: The output from the gyrotron is a microwave beam which is a Gaussian-like beam (essentially, an optical beam) in free space. It is transmitted through a four inch sapphire double disk window. The microwave beam passes horizontally through a cylindrical pipe containing microwave absorbing material at the outer edge. After bouncing off an "elbow mirror," the beam is focused into a two section microwave absorbing load, called a dummy load. The sample chamber containing the samples is located between the two load sections. The load is shown in the figures given below.

3. Sample Chamber. A special chamber was built for use as the sample test chamber. The chamber is a vacuum cross, with two vertical ports (up and down) and four horizontal ports. Microwave power passes through the cross vertically. Boron nitride (BN) windows are located at the top and bottom ports of the chamber. The four side ports of the chamber are used for vacuum pumping, an infrared (IR) camera, a visible CCD camera and a spare port. The cameras look directly at the sample being heated. The IR camera is protected against microwave power by a copper plate with cutoff holes. The CCD camera is protected by a shield with a pinhole through which the camera can see the sample.

4. Vacuum systems: The vacuum in the sample chamber is controlled separately from the vacuum in the CPI load sections above and below the chamber. It consists of a mechanical pump with a liquid nitrogen cooled trap. The mechanical pump is exhausted through a filter into a hose which is run away from the experimental area. A residual gas analyzer (RGA) is used to sample the gas coming from the chamber. The RGA samples the chamber using an adjustable leak valve. The RGA chamber is pumped by a turbomolecular pump. The CPI load sections are pumped by a separate turbo pump system.

As shown in Figure 5, sample chamber 14 located between two water load sections has BN windows at top and bottom and a BN crucible or container for the sample. In some cases, an inverted crucible was placed on top of the crucible and used as a cap for the sample in the crucible. The two camera ports are shown; a pumping port and a spare port are also on the chamber in the same plane but rotated 90 degrees. The RGA is connected to the chamber at a side port (and not to the water load as shown in the figure.) The research required a number of diagnostics to be employed during the experimental program. The infrared camera is an AGEMA camera which operates in the 8 to 12 μm wavelength range. It is cooled to liquid nitrogen temperature during the experiments. The hold time at that temperature is about 45 minutes, the amount of time required for the liquid nitrogen to boil off. This sometimes required stopping of the experiments at this interval to refill the camera with liquid nitrogen. The output of the camera is a map of the sample temperature in space. This allowed real time monitoring of the sample temperature during the microwave heating. The visible camera also indicated that a plasma was formed in some cases at the surface of the sample. Some of the visible camera images of the sample were recorded on video tape.

The visible camera was used to monitor the sample during the heating. When the sample became hot, it passed into a regime where it was visibly emitting, that is, "white hot." This image could also be studied in real time to see the degree of heating of the sample. In some cases, when powder was used, the powder particles could be seen to move or "jump" with the video camera. The images from the camera were also recorded on video tape. The RGA system sampled the gas flow exiting the chamber. The RGA display showed the constituents of the gas being pumped from the chamber. The pressure in the chamber did rise significantly during the heating. During microwave heating, new elements and compounds were observed on the RGA display. These new elements and compounds were given off by the sample as a result of the microwave heating. These were recorded in the lab notebook. They were also recorded by photographs of the RGA screen display. Some of these outputs were also recorded on a VCR.

The pressure in the sample chamber was found to rise during the microwave heating. Values of the chamber pressure were recorded during testing. The gas flow from the chamber was pumped through zeolite filters. These filters were kept in many cases and could be analyzed for their constituents. The microwave power going forward towards the sample was recorded. The reflected power could also be deduced form the measured power absorbed in the microwave loads and in loads in the gyrotron itself.

The samples were collected after the microwave heating runs. These were taken up to the CPI test lab for analysis by a scanning electron microscope. Nineteen samples were catalogued but only the results from experiment 4 will be discussed hereinbelow. During the course of the heating of the rutile sample, intense light emission was observed indicating high heating rates. In addition to seeing intense light emission, the video camera also showed that rutile particles were escaping from the crucible during the course of the heating experiments. The heating experiments were continued until it was found that power was being reflected back into the gyrotron microwave oscillator. Upon opening up the vacuum system, it was found that the lower BN window was damaged. The window had become coated with material which originated from the rutile sample in the crucible.

An analysis of the material coating the window was carried out by Geller Microanalytical Laboratory and the following report was generated. The window disk was a four inch diameter disk of BN which was in use as a vacuum window for microwave transmission. As a result of the microwave heating experiment, the disk failed and a small hole was created near the center of the disk. Surrounding the hole were a series of bands of different material.

A wide circular band, centered on the hole, contained titanium. The results indicate that the original starting material, TiO₂, has been reduced in fractional oxygen content and thus increased in fractional titanium content. In one band, the titanium fraction increased from 33% (atomic percent) in TiO2 to 42%. In two specific locations, the titanium fraction was very high with very low levels of oxygen dissolved within the metal. These layers have small amounts of oxide content but are primarily metallic titanium in nature rather than rutile.

Having fully described the preferred embodiments of the invention, variations and modifications may be employed without departing from the scope of the present invention. For example, although only one crucible is shown, multiple sample carriers may be used for batch processing without departing from the scope of the present invention. Furthermore, reaction chamber 12 may be modified to accommodate continuous processing, such as a conveyor belt or a rotating sample carrier, for example, without departing from the scope of the present invention. Additionally, chemical reactions may be induced to create other compounds by injecting different gases into the sample chamber 12 via atmospheric adjustment unit 13. Accordingly, the following claims should be studied to learn the true scope of the present invention.

Claims

What is claimed is:

1. A method of collecting pure elements from a compound, the steps comprising:

(a) placing the compound in a processing chamber;

(b) adjusting environmental conditions inside said processing chamber;

(b) applying energy to the compound in said processing chamber such that disassociation of the compound occurs to produce disassociated said elements in a gaseous state; and

(c) collecting said gaseous elements to thereby produce said elements from said compound.

2. The method of claim 1 , wherein said applied energy is from an electric arc.

3. The method of claim 1, wherein said applied energy is from a laser.

4. The method of claim 1 , wherein said applied energy is from a plasma torch.

5. The method of claim 1, wherein said applied energy is from a millimeter wave source.

6. The method of claim 5, wherein said millimeter wave source is a gyrotron.

7. The method of claim 5, wherein said millimeter wave source produces at least 110GHz radiation.

8. The method of claim 7, wherein said millimeter wave source produces either pulses or continuous wave.

9. The method of claim 1, wherein said applied energy is from a particle beam.

10. The method of claim 1 , wherein said method is a batch process.

11. The method of claim 1 , wherein said method is a continuous process.

12. The method of claim 1, wherein each constituents of said disassociated compound are formed in segregated zones.

13. The method of claim 1, wherein said environmental condition is an under pressurized condition.

14. The method of claim 1, wherein said under pressurized condition is less than 1 atmospheric pressure.

15. The method of claim 1, wherein said environmental condition is an induced gaseous condition.

16. The method of claim 15, wherein said induced gaseous condition is created by injection of gases into said chamber.

17. The method of claim 16, wherein said injected gases are mixed with said disassociated elements to form desired compounds.

18. The method of claim 1, wherein said element is a metal and said compound is an ore.

19. The method of claim 18, wherein said metal is titanium and said compound is a rutile.

20. An apparatus for producing pure elements from a compound, comprising: a process chamber for processing said compound; means for adjusting environmental conditions in said process chamber; means for supplying said process chamber with energy such that disassociation of the compound occurs to produce disassociated elements in gaseous state; and means for collecting said gaseous elements to thereby collect said elements from said compound.

21. The apparatus of claim 20, wherein said high energy source is an electric arc.

22. The apparatus of claim 20, wherein said high energy source is a laser.

23. The apparatus of claim 20, wherein said high energy source is a plasma torch.

24. The apparatus of claim 20, wherein said high energy source is a millimeter wave source.

25. The apparatus of claim 24, wherein said millimeter wave source is a gyrotron.

26. The apparatus of claim 24, wherein said millimeter wave source produces at least 110GHz radiation.

27. The apparatus of claim 26, wherein said millimeter wave source produces either pulses or continuous wave.

28. The apparatus of claim 20, wherein said high energy source is a particle beam.

29. The apparatus of claim 20, wherein said apparatus is for batch processing.

30. The apparatus of claim 20, wherein said apparatus is for continuous processing.

31. The apparatus of claim 20, wherein each constituents of said disassociated compound are formed in segregated zones.

32. The apparatus of claim 20, wherein said environmental condition is an under pressurized condition.

33. The apparatus of claim 32, wherein said under pressurized condition is below 1 atmospheric pressure.

34. The apparatus of claim 20, wherein said environmental condition is an induced gaseous condition.

35. The apparatus of claim 34, wherein said induced gaseous condition is created by injection of gases into said chamber by said environmental conditioning means.

36. The apparatus of claim 35, wherein said injected gases and said disassociated elements are mixed to form desired compounds.

37. The apparatus of claim 20, wherein said element is a metal and said compound is an ore.

38. The method of claim 37, wherein said metal is titanium and said compound is a rutile.