WO2007141017A2

WO2007141017A2 - Process for producing crystalline silicon and gaseous hydrogen

Info

Publication number: WO2007141017A2
Application number: PCT/EP2007/005034
Authority: WO
Inventors: Peter Plichta
Original assignee: Kunkel, Klaus
Priority date: 2006-06-10
Filing date: 2007-06-06
Publication date: 2007-12-13
Also published as: DE102006029282A1; WO2007141017A8

Abstract

The large reserves of oil-containing sands and shales are utilized for producing crystalline silicon, photosilicon or the fuel silane, or silicon nitride, silicon carbide. Decomposition of the hydrocarbon of the minerals into hydrogen and pure carbon/graphite so as to provide primary energy because the gases fluorine and hydrogen are used to form hydrogen fluoride in a highly exothermic reaction enables the sands and silicon-containing shales to be converted into silicon fluoride and/or calcium fluoride. In a novel cyclic process, the SiF<SUB>4</SUB> can be reacted with granular aluminium to produce crystalline silicon, with aluminium fluoride being formed in once again a highly exothermic reaction. AIF<SUB>3</SUB> is then decomposed again into aluminium and fluorine by electrolysis. Since cooling is necessary both in the preparation of aluminium fluoride and in the fluorination by HF and in the pyrolysis, electricity can be generated here by means of hot pressurized steam, which makes the aluminium recovery process cheaper. Overall, silicon is formed as crystal platelets which are converted either into photosilicon or into monosilane.

Description

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Process for the preparation of crystalline silicon and gaseous hydrogen

The reserves of oil-bearing sands (SiO ₂₎ and shale (siue ₂ + [CO _3] ^{2 ")} exceed known that the world oil reserves by a multiple. To separate the next technical methods applied, oil, and minerals, are ineffective and expensive.

The combustion materials needed to generate heat generate CO ₂ . So far, no one has come up with the idea of using the sand that is present in the mixtures as an energy source and of extracting new raw materials from the products.

An object of the present invention is to name such possible raw materials and to describe their technical representation.

The chemical considerations used in the process are characterized in that both the hydrocarbons present in the sands and slates take part directly in the reaction and also the SiO _{2 is} chemically modified in terms of reaction technology.

Oil-bearing sands / slates as starting materials are used for the preparation of large amounts of gaseous hydrogen and crystalline silicon, which can be used for the production of photosilicon or as a starting material for the preparation of silanes, silicon nitride and silicon carbide, oily sands here include mixtures of quartz sand with oils or tar products, which may also be caused by impurities.

The solution of the problem, according to claims 11 to 17, will show that it is possible to obtain SiF ₄ from silicates in the process used in order to represent and separate crystalline silicon, as well as silicon nitride and silicon carbide by changing the process and the fabric to be mixed. The process will now be discussed in individual paragraphs.

A1) With patent a) DE 21 53 954 and b) DE 195 33 765 it is known that in the combustion of fluorine with hydrogen, the resulting hydrogen fluoride silicate-containing rock completely in gaseous constituents SiF ₄ , AIF ₃ (see a), etc. transformed. The resulting silicon fluoride is rendered harmless with sodium hydroxide in this process (see b).

A2) containing oil sands can be treated with the water formed during combustion very hot hydrogen fluoride (about 3,000 ⁰ C), creating in the main silicon fluoride.

A3) The gaseous silicon tetrafluoride can be prepared in the form of the salt SiF4 ^• 2KF = K ₂ [SiFβ] with aluminum grits according to the equation:

3SiF ₄ + 4Al → 3Si + 4AIF ₃ + 1172.7 kj with exclusion of air, whereby the silicon accumulates in the crystal lamina and can be separated by fine sieves.

A4) The resulting aluminum fluoride is known to be soluble neither in acids nor in alkalis and is combined with the AIF _{3 produced} in A1). After separation, it can be decomposed by electrolysis again in aluminum and fluorine.

A5) The mineral oil of the sands is now pyrolyzed to "luminous gas" at the high temperatures. This gas mixture will be largely free of CO and CO ₂ , by working on combustion of the fluorine with a slight excess of hydrogen. The gas will therefore consist predominantly of hydrogen derived from the carbon chain. The carbon itself is deposited at the given working temperature as a graphite-like residue.

A6) The heat released at the furnace during the thermal reaction of the main process can drive the turbine of a dynamo as strongly compressed water vapor. The electric currents of the generators are bundled. A7) The most important ceramics used in the art - silicon nitride (with its remarkable thermal conductivity) and silicon carbide (with its diamond-like hardness) - can be achieved at the same reaction start by different reaction conditions, as explained in A8) to A10).

A8) In the equation under number A3), 3 moles of silicon and 1172 kj are on the right side. If necessary, this crystalline silicon can now be reacted directly with pure cold nitrogen to silicon nitride after ignition, because the reaction is highly exothermic. (Si ₃ N ₄ is a solid noble gas [Plichta].) The resulting heat is used, as described in Section A6).

A9) Also, the carbonaceous residue obtained in item A5) can be converted exothermically with the obtained crystalline silicon to silicon carbide.

A10) The available crystalline silicon is surface-active and could be catalytically treated with hydrogen to produce monosilane. This

TvϊonosTian "can be taken from the TteaWion space and subjected to another catalytic pressure reaction at another location

Si + SiH ₄ → (with cat as Pt oa) → Si (SiH ₄ ) ₄ + SiH _n (SiH ₄ ) _m + Si _n H _{m represent} longer-chain silanes, both in the technology of the fuel cell, in ceramic-based engines, as can also be used with scramjet drives.

The invention is realized in a first basic idea that used in a process used oily sands and shale and their mixtures are used as starting materials for the preparation of crystalline silicon and hydrogen gas and for the production of silicon nitride, silicon carbide, monosilane and higher silanes by the Starting materials in stainless steel autoclave treated with the use of coming fluorine and hydrogen to the effect that the resulting very hot hydrogen fluoride rocks the silicate rocks in gaseous components such as silicon tetrafluoride and aluminum trifluoride to the very hot gaseous SiF ₄ in the form of its salt potassium hexafluorosilicate with aluminum gries to release very to convert a lot of heat into crystalline silicon in the form of crystal lites, with the simultaneous accumulation of amorphous aluminum fluoride using is separated from a Abschwemmmethode and fine sieves and the thus obtained aluminum trifluoride is combined with the original already formed AIF ₃ , and then converted back into metallic aluminum by fused-salt electrolysis - freed from fluorine - himself into the original process for Can be used, so that the separated crystalline silicon can be purified by zone melting process, or can be chemically transformed directly with pure cold nitrogen with release of heat into silicon nitride, instead of nitrogen at the used carbon, which is formed even in the reaction Silicon carbide is formed, which plays a role as silicon nitride in the ceramics industry, whereby the crystalline silicon is to be catalytically upgraded with hydrogen and / or monosilane to monosilane or higher silanes, whereby the used mineral oil of the sands lie the role of the primary energy takes over the factor and thereby pyrolytically at temperatures above 1,000 ° C largely decomposed into hydrogen and a graphite-like mass, so that it is possible to deprive the reaction of the recovered hydrogen of the hydrocarbon chain.

that crystalline silicon (see above) can take on a leading energy-efficient role in the future, because the silanes mentioned above provide atomic hydrogen at temperatures above 350 ° C, which has a half-life of half a second and thus forms the strongest reducing chemical agent, while the resulting silicon radicals are energetically compared with the oxidizing power of atomic oxygen, which can easily be observed in atmospheric thunderstorms.

The process is further developed that in schists a high calcium carbonate content provides calcium fluoride, which can be used in the production of fluorine. The resulting CO ₂ is not a hindrance to the further course of the reaction.

The method is further extended that the flurosilane produced by the combustion is not obtained from expensive raw silicon - such as chlorosilanes in the silicone oil industry - but, as in the problem and in claim 1, from sand. The primary energy, to reiterate it, is provided by the hydrocarbon content of the oil sands and oil shale. In a summary consideration, the following becomes apparent in the first basic idea.

The crude oil stocks are calculable limited in time. Before the auto industry, aviation, the arms industry and space travel, for example, switch their combustion engines to silicon, which is known to burn atmospheric nitrogen in a hot chamber and deliver atomic hydrogen, a way must be found of coming down from the high oil prices. The very large stocks of oily sands and slates provide the conditions for this. By decomposing the hydrocarbon of the minerals, supplying primary energy, into hydrogen and carbon residues by using hydrogen fluoride with the gases fluorine and hydrogen under the strongest exothermic reaction, the sands and siliceous schists can be converted into silicon fluoride. The SiF ₄ can now be converted with aluminum grit into crystalline silicon, again under the highest exothermic reaction aluminum fluoride is formed. AIF ₃ is broken down into aluminum and fluorine by electrolysis. Since in the aluminum fluoride representation

be won, which makes the aluminum extraction process cheaper. Overall, this results in silicon in crystal sheets, which are either converted into photosilicon or in monosilane or in higher silanes. The reaction process can also be controlled to switch to the production of silicon nitride or silicon carbide. The hydrogen can be passed as a combustible gas, largely free of carbon monoxide, carbon dioxide and nitrogen in existing gas supply networks.

Another object of the present invention is to provide a cyclic process in which only a certain amount of fluorine and aluminum is used in addition to the oil sand.

The combustion materials needed to generate heat generate CO ₂ . So far, it has not been taken up the idea to use the sand present in the mixtures themselves as an energy source and to extract new raw materials from the products, whereby the oil pitch present in the sands and slates itself becomes the supplier of gaseous hydrogen. The solution of the object, according to claims 1 to 10, 18, 19, will show that this amount is constantly recycled, so that only a part of the direct current must be made available to a permanent electrolysis to obtain aluminum and to ensure fluorine, and that it is possible to obtain SiF ₄ from silicates in the process to be used to thereby form and separate crystalline silicon. At the same time caused by the tremendous heat of the burned hydrogen / fluorine mixture to SiF ₄ by pyrolysis of the hydrocarbon chain of the oil mixture under exclusion of air large amounts of hot hydrogen gas, which is partially removed from the cyclic process, and / or fed back into the cycle of the hydrogen used.

In a second aspect, therefore, the invention provides a process for the preparation, in particular in cyclic, large-scale, of crystalline silicon / photosilicon or the fuel silanes or ceramics silicon nitride or silicon carbide and gaseous hydrogen from oily sands and / or slates using aluminum and the mixture of fluorine and hydrogen, the 4,000 ⁰ C hot hydrogen fluoride delivers when burning and are always used in a cycle again, so that only a subset of electric power must be fed.

The cyclic process is now to be explained in detail in detail sequentially chemical technically. Fig. 1 shows a series of large-scale production equipment that begins with the fact that oily sands / shale reach the mechanical decomposition plant I on mechanical transport routes.

1) With patent a) DE 21 53 954 and b) DE 195 33 765 it is known that in the combustion of fluorine with hydrogen of the resulting hydrogen fluoride silicate-containing rock completely in gaseous constituents SiF ₄ , AIF ₃ (see a), etc. transformed. The resulting silicon fluoride is rendered harmless with sodium hydroxide in this process (see b).

2) Oil-bearing sands can be treated with the water formed during combustion very hot hydrogen fluoride (about 3,000 ⁰ C), so that in the main silicon fluoride is produced (one, one). This is very much heat free. A necessary cooling process of the reactor chamber produces electricity using steam.

3) The heat pyrolyzes the involved oil pitch to carbon / graphite, which can be taken from the process (2, 2). If shale is present, calcium oxide CaO is also formed to be reused elsewhere.

4) The gaseous SiF ₄ , possibly contaminated by AIF ₃ , and traces of potassium fluoride and other metal fluorides, is now transferred together with the large amounts of hot hydrogen gas to (3, 3). There it is treated with aluminum granules (ten, 10) according to the Thermit method in the form of the salt SiF ₄ ^• 2KF = K ₂ [SiF ₆ ] according to the equation

3SiF ₄ + 4Al → 3Si + 4AIF ₃ + 1172.7 kj converted into crystalline silicon under exclusion of air. The excessively released heat in (one, 1) and (3, 3) can be removed from the system by the production of hot water vapor by built-in cooling coils and converted into three-phase current (fourteen, fourteen), which is later fed in the electrolysis.

5) The incoming in (four, 4) incoming mixture of crystalline silicon, AIF ₃ and H ₂ is free of Co and Co ₂ , because it works under exclusion of air. If the pitch-oil mixture contains shale, in addition to calcium oxide, CO _{2 is formed} , which is separated in (4, 4) in aqueous solution with calcium hydroxide. The CO ₂ can thus be bound with the CaO obtained in (2, 2) as calcium carbonate and removed from the system.

6) The bulk of the hydrogen is fed into existing hot gas piping systems (7, 7), while the stoichiometric amount of H ₂ required for the circuit is re-fed (one, 1) via a line (8, 8).

7) The dried, powdered AIF ₃ (insoluble in water and alkali) freed of water by filter pressing is subjected to fused-salt electrolysis (Nos. 9, 9). For this purpose, electricity produced with self-generated hydrogen will be used (thirteen, 13). In addition there are the bundled streams (fourteen, fourteen) (one, one) and (three, three). The AIF ₃ freed of water by filter presses can be reacted with sodium hydroxide solution in Na ₃ [AIF ₆ ] (cryolite). From this, aluminum can be produced electrolytically with Al ₂ O ₃ . Of K ₃ [AIF _6] Also potassium fluoride or KF ^■ 3HF can win, is obtained from the electrolytic fluorine gas. In order to convert AIF ₃ directly into AI and F ₂ , separate process steps are required.

Normally, the presentation of crystalline pure silicon and the production of aluminum have nothing in common, except that either halogen chlorine or fluorine-containing compounds are needed for both processes. However, the process described here produces synthetic cryolite (icestone), which is found on the coast of southern Greenland.

In the electrolytic production of raw aluminum, about 30 kg of a mixture of cryolite and potassium fluoride is required per ton of lavishly purified bauxite (Bayer process) in order to lower the melting point of the aluminum oxide by 1,000 ° C. Thus, large quantities of raw aluminum are co-produced, which can be sold on the world market precisely because the heat of the thermite process can be used, which lowers production costs. Characteristics of the process is the recycling of the whole used fluorine and aluminum, which is only possible with huge amounts of electricity. These are to be taken only from the primary energy of the hydrogen, which is released during the pyrolysis of the petroleum products and the heat of Thermitreaktion. In contrast, in the conventional production of aluminum or silicon, the electric current can not be obtained from the oil sands / slates, because their combustion would be much too expensive and harmful to the environment. Any electricity generated from coal or hydrocarbons is expensive and produces carbon dioxide during combustion. Only electricity generated from hydropower is ultimately produced by sunlight. Thus, it is a core objective of the invention to produce photosilicon in such a cost-effective manner in accordance with the method steps described that a quantity of solar cells that is unimaginable today produces the electricity that still has to be subsidized today.

8) The aluminum (10, 10) produced during the electrolysis will be cyclically reused in (3, 3). The unneeded part of the alumi- It can be taken from The resulting F ₂ (eleven, 11) is re-used lossless in (one, 1).

9) In the equation under 4.) are on the right side 3 moles of silicon and 1172 kj. Crystalline silicon is currently being prepared by a complex process involving the use of coal, high electrical costs and fractionation of chlorosilanes followed by pyrolysis. The price is very high as it has been agreed worldwide. The new cyclic process would reduce the kilogram price for photosilicon to one hundredth.

10) If necessary, then this crystalline silicon after ignition directly with pure cold nitrogen to convert silicon nitride, because the reaction is highly exothermic. (Si ₃ N ₄ is a solid noble gas [plichta].) The most important ceramics used in the art - silicon nitride (with its remarkable thermal conductivity) and silicon carbide (with its diamond-like hardness) - can be obtained, because even the very pure Carbon from (2, 2) can be used here.

11) The available crystalline silicon is surface-active and could be catalytically treated with hydrogen to produce monosilane. This monosilane can be removed from the reaction space and converted into long-chain silanes in another patent application. These are to be used not only in the space travel, since they supply atomic hydrogen in the heat (Plichta). The atomic hydrogen can also be used in a fuel cell.

Process for the cyclic large-scale representation of crystalline silicon / photosilicon or the fuel silanes or ceramics silicon nitride or silicon carbide and very large amounts of gaseous hydrogen, characterized in that oily sands / shale as a mixture of energy-containing hydrocarbons and silicates (SiO ₂ ), contaminated by potassium Aluminum silicates and carbonates are used so that the hydrocarbons, including tar, are subjected to a pyrolysis above 1000 ° C. The gaseous hydrogen (H ₂ ) released by the heat can for the most part be converted into electricity by cooling with cold water via steam turbines and then fed into a gas network, while the remaining part of the hot hydrogen is burned with a certain amount of gaseous fluorine at a heat of about 4,000 ° C where the oil / pitch sands are pyrolyzed, so that the very hot hydrogen fluoride is immediately mixed with the silicon of the oily sands (see above). is converted into gaseous Siliziumtetrafiuohd and water vapor, wherein the hot SiF ₄ , contaminated with HF, is passed directly into a combustion chamber, the aluminum grit is continuously supplied. As in the case of the thermite process, the aluminum is transformed into powdered aluminum fluoride, which is stable to aqueous bases and can be filtered off in order subsequently to be electrolytically reacted in the form of the anion [SiF ₆ ] ^{2 '} , so that aluminum and fluorine are formed again. The process is thus cyclically characterized in that the same aluminum and fluorine are used again and again under optimum conditions, the amount of direct electrical current being ensured by the process, since stoichiometrically liberates stoichiometrically 1172 kj per unit of time in the above-mentioned thermite process that a second time by cooling with pre-heated water, 300 ° C hot water vapor-phase current-producing "J ^ aa ^'avsbei = the = Keisse ΛAtesser = sfs -Gft -arid Stétié = the ΨjrQτfse ^ πtπDTπrfien ^ is here because in the emergence of Silicon tetrafluorides by the combustion of hydrogen fluorine in third place a lot of heat is generated, which can also be incorporated as an amount of electricity in the pyrolysis process. Since this cyclic process transforms SiF ₄ into crystalline, very pure silicon, a comparison with today's three-stage production method with coke, electric current (over 2,000 ° C), and pyrolysis of chlorosilanes is worthwhile Primary energy is derived from a pitch oil, which is normally not to be used, because the sand (and feldspar or slate) interfere, while in the cyclic method used here in addition to silicon large amounts of hydrogen are generated and pure carbon or Graphite, as hot hydrogen fluoride transforms all impurities in the sands into gaseous components, which can later be separated off with lime and discarded.

The large stocks of oily sands and slates provide a basis for being able to produce cyclic crystalline silicon, photosilicon or the fuel silane, silicon nitride or silicon carbide. By decomposing the hydrocarbon of minerals, supplying primary energy, into hydrogen and pure carbon / graphite, because hydrogen fluoride is used with the gases fluorine and hydrogen under the strongest exothermic reaction, the sands and siliceous schists can be converted to silicon fluoride and / or calcium fluoride. In a completely new cyclic process, the SiF ₄ can be refined with aluminum grit into crystalline silicon, again producing aluminum fluoride under the highest exothermic reaction. AIF ₃ is now broken down again into aluminum and fluorine by electrolysis. Since it must be cooled both in the aluminum fluoride and in the fluorination by HF and pyrolysis, can be obtained here with hot strained steam electricity, which makes the aluminum extraction process cheaper. Overall, therefore, silicon is produced in crystal sheets, which are either converted into photosilicon or in monosilane. The reaction process can also be controlled to switch to the production of silicon nitride or silicon carbide. The hydrogen can be passed as a combustible gas, free of carbon monoxide, carbon dioxide and nitrogen in existing gas supply networks. In total, the primary energy of the hydrogen content of the oil pitch is determined using a -fee-süsaπnteπ! 44e! 3ge 4'-OR ^ tasisktfs ^ Rd -F-! YGr = SG = k = ρist3 "ifies Siiiziüm = aiϊd τnfesseF5t5ff that in the cyclic process only a certain amount of electricity is used, which consists of self-produced hydrogen can be won.

Claims

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1. A process for the preparation, in particular in cyclic, large-scale manner, of crystalline silicon, photosilicon or the fuel silanes or ceramics silicon nitride or silicon carbide and gaseous hydrogen, characterized in that oily sands or slate as a mixture of energy-containing hydrocarbons and silicates (Siθ ₂ ), possibly contaminated by potassium aluminum silicates and carbonates, are used so that the carbon monoxide, for which especially tar is subjected to pyrolysis above 1000 ° C., that the gaseous hydrogen liberated by the heat (H ₂ ) is converted into electricity and / or can then be fed into a gas network, that the remaining part of the hot hydrogen with a certain amount of gaseous fluorine at high heat over 3,000 ° C, in particular from about 4,000 ° C, is burned, and / or Pechsande are pyrolyzed, so that the hot hydrogen fluoride f is reacted with the silicon of the oily sands to form gaseous silicon tetrafluoride and water vapor, wherein the hot SiF ₄ , in particular contaminated with HF _{1 is passed} into a combustion chamber, to which aluminum continuously, in particular as aluminum umgries is supplied.

2. The method according to claim 1, characterized in that in the Thermitverfahren the aluminum turns into pulverulent Aluminiumflu- orid, which is stable to aqueous bases and can be filtered off, to thereafter electrolytically reacted in the form of the anion [SiF ₆ ] ^{2 "} can be used to produce aluminum and fluorine again.

3. The method according to claim 1 or 2, in that cyclically geke nnzeich net that under optimal conditions repeatedly the same aluminum and fluorine are used, the amount of direct electrical current is ensured by the method, as in the above-mentioned Thermitverfahren disturbing chiometrically per unit time 1172 kj become free, so that here for a second time by cooling with preheated water 300 ° C hot water vapor can produce three-phase flow, the hot water is taken in place of the pyrolysis, because in the formation of silicon tetrafluoride by the combustion In the cyclic process, the FiF _{4 is transformed} into crystalline, very pure silicon in the cyclic process, which generates a large amount of heat, which can also be incorporated into the pyrolysis process as an amount of electricity.

4. The method according to claim 1, characterized in that in slates a high calcium carbonate content provides calcium fluoride, which can be used in the production of fluorine. The resulting CO ₂ can be precipitated with the previously obtained calcium oxide.

5. The method according to claim 1, characterized in that from the generated crystalline silicon according to the prior art photosilicon can be obtained.

6. The method according to claim 1, characterized in that the method can be chemically modified so that can be represented by the use of nitrogen to produce silicon nitride.

7. The method according to claim 1, characterized in that at (one, 1) resulting pure carbon for the production of silicon carbide can be used.

8. The method according to claim 1, characterized in that after (four, 4) separated by shakers crystalline silicon made highly reactive by etching and so catalytically by means of pressure synthesis to monosilane (SiH ₄ ) can be hydrogenated. The monosilane is removed from the reaction space and can be converted by a process into longer-chain silanes, which can be used both in fuel cell technology, in ceramic-based engines without mechanical elements, and in scramjet drives.

9. The method according to claim 1, characterized in that the at (seven, 7) resulting hydrogen for power generation in the electrolysis (9, 9) can be applied.

10. A process for the cyclical large-scale preparation of crystalline silicon

fcvoi'Λrff _Q.jJo »-o

-QjlirxJi-irraraiiSri / rl or silicon carbide and very large amounts of gaseous hydrogen according to claim 1, characterized in that oil-containing sands / shale are used as a mixture of energy-containing hydrocarbons and silicates (SiO ₂ ), contaminated by potassium aluminum silicates and carbonates, that the hydrocarbons, including tar, undergo pyrolysis above 1,000 ° C. The gaseous hydrogen (H ₂ ) released by the heat can for the most part be converted into electricity by cooling with cold water via steam turbines and then fed into a gas network, while the remainder of the hot hydrogen is heated with a certain amount of gaseous fluorine burned at about 4,000 ° C. where the oil / pitch sands are pyrolyzed so that the very hot hydrogen fluoride is immediately reacted with the silicon of the oily sands (see above) to form gaseous silicon tetrafluoride and water vapor, the hot SiF ₄ , contaminated with HF, is passed directly into a combustion chamber, the aluminum grit is continuously supplied. As in the case of the thermite process, the aluminum is transformed into powdered aluminum fluoride, which is stable to aqueous bases and can be filtered off in order subsequently to be electrolytically reacted in the form of the anion [SiF ₆ ] ^{2 "} , so that aluminum and fluorine are formed again. The process is thus cyclically characterized in that the same aluminum and fluorine are used again and again under optimum conditions, the amount of direct electrical current being ensured by the process, since stoichiometrically liberates stoichiometrically 1172 kj per unit of time in the above-mentioned thermite process that here for a second time by cooling with preheated water 300 ° C hot water vapor can produce three-phase current, the hot water is taken in place of pyrolysis, because in the formation of silicon tetrafluoride by the combustion of hydrogen and fluorine in third place very much Heat is generated, the same s as an amount of electricity in the pyrolysis process can flow. Since in this cyclic process, the SiF _{4 is converted} into crystalline very pure silicon is

three stages with coke, electric current (over 2,000 ° C) and pyrolysis of chlorosilanes rewarding, because the primary energy used in the cyclic process comes from a pitch oil, which is normally not to use, because the sand (and feldspar or slate ), while in the cyclic method used here, in addition to silicon, large amounts of hydrogen are produced and pure carbon or graphite, since hot hydrogen fluoride transforms all impurities in the sands into gaseous components, which can later be separated off and discarded with lime.

11. A process for the use of oily sands and shale and their mixtures as starting materials for the production of crystalline silicon and hydrogen gas, and optionally for the production of silicon nitride, silicon carbide, monosilane and higher silanes, by treating the starting materials with the used fluorine and hydrogen be that the resulting hot hydrogen fluoride, the siliceous rock transformed into gaseous components such as silicon tetrafluoride and aluminum trifluoride, to convert the hot gaseous SiF ₄ in the form of its salt potassium hexafluorosilicate with aluminum or Aluminiumgries releasing heat into crystalline silicon in the form of crystal lamellae.

12. The method according to claim 11, characterized in that the simultaneously occurring amorphous aluminum fluoride is separated by means of a Abschwemmmethode and fine sieves and the thus obtained aluminum trifluoride is combined with the originally already formed AIF ₃ , and then converted back into metallic aluminum by fused-salt electrolysis - free of fluorine - to be, which itself can be used again in the original process.

13. The method according to claim 11 or 12, characterized in that the separated crystalline silicon purified by zone melting process or can be directly transformed with pure cold nitrogen with the release of heat into silicon nitride, using instead of nitrogen in use Carbon, which is formed even in the reaction, silicon carbide is formed, which plays a role as silicon nitride in the ceramic industry, wherein the crystalline silicon is to be catalytically upgraded with hydrogen and / or monosilane to monosilane or higher silanes.

14. The method according to any one of claims 11 to 13, characterized in that the used mineral oil of the sands takes over the role of the primary energy supplying factor and in this case itself pyrolytically decomposed at temperatures above 1000 ° C largely in hydrogen and a graphite-like mass.

15. The method according to claim 14, characterized in that it is possible to withdraw the reaction of the recovered hydrogen of the hydrocarbon chain and in existing piping systems of natural gas while crystalline silicon (see above) can take on a leading energy-efficient role in the future, because the silanes mentioned above provide atomic hydrogen at temperatures above 350 ° C, which has a half-life of half a second and thus the strongest reducing chemical Active ingredient, while the resulting silicon radicals are energetically compared with the oxidation power of atomic oxygen, which can be easily observed in atmospheric thunderstorms.

16. The method according to claim 11, characterized in that in slates a high calcium carbonate content provides calcium fluoride, which can be used in the production of fluorine, wherein the resulting CO _{2 is} not a hindrance to the further course of the reaction.

17. The method according to claim 11 or 12, characterized in that "TΓHS Tjöffch

ΕϊtiθTi "Tπcffi ^" äTßr'ilSjfeffi

is derived from sand, the primary energy being supplied by the hydrocarbon content of the oil sands and oil shale.

18. The method according to any one of claims 1 to 3, characterized in that in the electrolytic production of raw aluminum from lavishly purified bauxite (Bayer process), a mixture of cryolite and potassium fluoride is required to the melting point of the aluminum oxide by about 1,000 ° C to lower.

19. The method according to any one of claims 1 to 3 or 18, characterized in that the recycling of the whole used fluorine and aluminum is realized by using high amounts of electricity from the released primary energy of hydrogen in the pyrolysis of the oily sands, Slate or petroleum products and the heat of thermite reaction.