rexresearch.com

---

---

---

Inventor(s):     ZHEZHERUN OLEKSANDR PETROVYCH [UA]; ZUZANSKYI YURII MECHYSLAVOVYCH [UA]; BOLOTOV BORYS VASYLIOVYCH [UA]; BOLOTOVA NELLI ANDRIIVNA [UA]; BOLOTOV MAKSYM BORYSOVYCH [UA]; BOLOTOV ILARION MAKSYMOVYCH

IPC: C01B33/00

Abstract -- The invention relates to processes for preparation of elements, in particular of elementary silicon, which can be used for the preparation of novel materials.

1 -- Silicon extraction method includes extraction of high-pressure elemental silicon from chemical elements of aluminum and phosphorus by application of electric current with density of more than 10^11 amps/m^2 to the mixture of crystalline matters containing oxygen, aluminum and phosphorus, which differs as follows: batch mixture undergores preliminary preparation by adding copper and zinc and the subsequent jopint alloying.

2 -- The method described in Para. 1 which differs as follows: copper and phosphorus are alloyed according to the percentage ratio: 82% copper and 18% phosphorus.

3 -- The method described in paragraph 1, which differs as follows: copper and phosphorus are alloyed under the temperature not greater than +1050 C.

4 -- The method described in Para. 1, which differs as follows: after alloying copper and phosphorus, up to 30% aluminum is infused to the total volume of copper.

5 -- The method described in para. 1, which differs as follows: after the copper-phosphorus-aluminum alloy is obtained, zinc in the amount of 1-15% from the total volume of alloy is infused.

6 -- The method described in para. 1, which differs as follows: after the molten mass has cooled down, silicon is extracted by dissolving in nitric acid with the subsequent drying until silicon powder is formed.

Useful model belongs to the methods of obtaining elements, in particular silicon which may be used to obtain new materials.

There are known methods of obtaining silicon by the carbothermal restoration of silicon earth-containing material, subsequent refining, and infusion of alloying additives in the converter, feeding it into the holding furnace, sawing of melted silicon with inert gas, removal of powder from the pulverizing jet and subsequent separation from the inert gas (1).

There is a known method of electro-thermal extraction of silicon (2) and its alloys in ore electrical furnaces.

This methods involves supplying of current from the power source to the electrodes, submersion into the batch, starting of the arc under the layer of batch materials, renewal and output of silicon from the furnace: in this case, a current fed to the primary output electrodes of the power source is being straightened while current of the same polarity coming from the secondary output electrodes of the power source is being fed to the electrodes, and then after the arc is started, current goes through the batch mixture and furnace hearth and fed to the secondary output electrodes of the opposite polarity.

There is a known method of smelting silicon (3) in the ore thermal furnace which allows to increase the percentage of its yield from the raw materials. Silicon is being smelted in the 3-electrode furnace with carbothermal restoration of batch mixture containing silcon earth. During smelting, each 1.5-2 hours a mixture of carbon-containing reducing agents and quartzite is input into the intra-electrode space in the correlation which ensures mass correlation in the mixture C:SiO2 = 0.5-0.75.

There are known methods of obtaining elemental silicon, based on the restoration of silicon oxide by carbon-containing matters upon the following reaction:

SiO2 + 2C > Si + CO.

However, the main deficiencies of the aforementioned silicon extraction methods is high power consumption and labor content of chemical and physical process involved in the production technology, which leads to the increased cost of the end products and also large amount of production waste which significantly deteriorates ecological situation on the territory and affects human health.

The closest method of achieving technical result is the method of obtaining compact silicon of other crystalline modification by treating regular silicon  under the pressure less than 20 MPa (4). All technologically used methods of extracting elemental silicon are based on the extraction of silicon-containing oxide materials in the process of restoration, carbothermy. This method is based on the transformation (transmutation) of other chemical elements of aluminum and phosphorus into elemental silicon.

Transformation is achieved by the electric current passing through the mixture of crystalling substances containing main elements, Al, P with density of the electric current no less than 10^11 A/m^2.

The goal of the proposed useful model is improvement of silicon extraction technology as a result of reduction of power consumption and labor content by selecting such chemical and physical processes during its production which would have allowed to obtain new technical result and more ecological production process.

Thas task is resolved as follows: silicon is obtained from chemical elements of aluminum and phosphorus by application of electric current with density no more than 10^11 A/m^2 to the batch mixture, from crystalling matters containing oxygen, aluminum, and phosphorus; in order to increase the output of silicon copper and phosphorus are preliminary alloyed according to the percentage ration of 82% copper to 18% (not more) of phosphorus under the temperature not greater than +1050 C., and after alloying of copper and phosphorus, up to 30% of aluminum is infused to the total volume of copper. After the copper+phosphorus+aluminum molten mass is obtained, zinc in the amount of 10-15% from the total volume of molten mass is infused. After the molten mass has cooled down, it is dissolved in nitric acid with the subsequent drying until silicon poweder is obtained.

Thus obtained silicon represents the product of apotropous modification of silicon isosters as a result of nuclear transformation of aluminum phosphide into chemically pure silicon.

Test analysis showed that this type of silicon is quite inert substance which cannot be dissolved in hydrochloric, sulfuric, etching and other tyres of acid and even in nitro-hydrochloric acid (aqua regia). It is not dissolved in the fluxes of such metals as aluminum, copper, iron, and others, does not form alloys with them, does not oxidize under the temperature of 3000 C., and does not form carbides.

Fig. 1 shows the appearance of silicon powder after the multiple magnifying by electronic microscope.


Technical result of the proposed useful model is broadening of the arsenal of technical means, namely extraction for the first time of silicon of high-pressure crystalline modification from other chemical elements in conditions of regular atmospheric pressure...

Energy mass analyzer EMAL-2 was used for the purpose of mass spectroscopic analysis of the output mixtures and products of transformation upon the method of determination of silicon in the fraction-less sample evaporation mode and registration on photo film after division of the flow of ions. Peaks of silicon isotope ions were observed in the mass spectraa of the product: single-charge 28, 29, 30 and double-charged 14, 14.5, and 15 with relative intensiveness, which corresponds to the master sample of silicon. Trace quantities of silicon were found in the mass spectra of the output mixture.

Roentgenograms were recorded on the x-ray diffraction meter DRON-4 SiK a-monochromatic radiation and compared the roentgenograms of the output mixture, product and the product residuum after acid treatment.

Results obtained for the product comparing to the output mixture confirm the formation of silicon during nuclear transformation (transmutation) of aluminum and phosphorus. Gravimetric analysis showed the presence of 18% of silicon in the product obtained.

The experiments conducted by the authors showed that silicon is formed from other chemical elements of the output mixture with density of the electric current less than 10^11 A/m^2 is discovered by the analysis methods described above.

Silicon obtained upon the proposed method may be used in the production of  lacquer and paint and in heat-insulating materials, electronics, optics, and jewelry, to process natural minerals and stone, in npolishing and grinding pastes and suspensions, in plates and supports of semiconductiong materials, fiber optic cables, &c...

References

(1) Karl Fovall, Norwegian Patent #2055812 (1996): Silicon Powder & Method of its Continuous Extraction".

(2) Russian Patent RU95100576 (12996); Method of Smelting Silicon and its Alloys".

(3) Russian Patent RU1628443 (1996);  "Method of Smelting Silicon".

(4) V. Kazbanov, et al.: Russian Patent RU2140110 (1997); "Silicon Extraction Method"