SU874604A1 - Method of continuous production of elements oxides - Google Patents

Description

(54) METHOD OF CONTINUOUS PRODUCTION OF ELEMENT OXIDES

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The invention relates to the production technology of oxides of elements, for example, SiO, AlaOj, MgO, liOi and PbjO, used in semiconductor technology, electrical engineering, optical instrument making and other parts of the new technology.

The content of impurities in the oxides used in these areas is limited in very small amounts, on the order of 10% by weight, and they can only be used in dispersed form with particle sizes up to 2000 µm.

A known method for producing dispersed oxides of elements by the phase-phase hydrolytic conversion of their halgeneids in a flame of a burner in oxygen of the air. At this, besides the target product, hydrogen chloride is formed, and 6-free chlorine remains in the abgas, which is suppressed with nitrogen or water vapor 1.

The disadvantages of this method are the formation of chemically aggressive and toxic substances that complicate the technology and working conditions, as well as the need and complexity of deep cleaning of both the initial halide and the air and steam supplied.

The closest to the proposed technical essence and the achieved result is the method of continuous production of alumina by decomposing aluminum hydroxide in a furnace with a hot gas stream, the hydroxide being previously dried with exhaust gases in a cascade of fluidized bed drying chambers 2.

The disadvantage of this method is the preparation of a polydisperse oxide containing Q pieces of various sizes. To obtain a uniform, highly dispersed product, an energy-intensive grinding process is necessary. In addition, at the stage of step drying and intermediate transportation, as well as during grinding, the substance is contaminated due to the impossibility of achieving the required sealing of the equipment, the complete elimination of corrosion and erosion of its elements.

Studies show that in such

20 and similar conditions reach the content of impurities at the level of 1-5-10 mass./o and more.

Filtration, drying and grinding processes also require the additional cost of a significant amount of energy and labor.

The purpose of the invention is to increase the dispersion of the product and reduce the content of impurities in it.

This goal is achieved by thermal decomposition of the compounds of the corresponding elements with a content of from 20 to moisture, which is fed to the heated layer of the target product, taken in an amount of G 3-U AT, where, calculated using the formula G, is the amount of the target product, A is the process productivity per unit of time, T is the duration of decomposition.

In addition, the starting compound is supplied when the decomposition temperature of the compound is reached in the layer.

Getting into the mobile dispersed layer and mixing the initial compound with it is intensely evaporated and quickly hardens, since the heat transfer surface of the dispersed layer is very large, which gives a large surface contact (heat transfer) with the liquid phase, and the temperature difference between the layer and the liquid is also large (more than 300 ° C). Under these conditions, intense vaporization occurs with overheating and an increase in the vapor volume, which ensures solidification in the dispersed fine-grained state and without the formation of conglomerates, and the process of dehydration and decomposition goes uninterrupted.

The content of the minimum amount of impurities is achieved by various methods of purification and synthesis of the initial compounds, and in carrying out the process of decomposition and obtaining the target oxide, the task is to create conditions that prevent the contamination and increase of the Kani content of impurities. Conducting dewatering and decomposition in one chamber and arranging filtration stages, drying, grinding and transportation of material reduces contamination of the finished compound and provides oxides with an impurity content of 1 10 mass, / o and less.

The moisture content up to W / o corresponds to its content in the initial compounds when they are obtained before filtration. A minimum content of 20% still gives sufficient mobility required for feeding into the furnace, mixing with the dispersed layer and obtaining the required vaporization.

Thermal calculations and experiments show that to create a heat exchange surface that ensures complete evaporation and overheating of water, the amount of the loaded layer of the target product must be at least 3 AT. The loading of the target product in the amount of more than 10 AT is already useless and causes furnace overload.

Example J. A horizontal electric furnace with rotating strokes for moving a substance is loaded with 168 kg (7 AT) of the target product — high purity silicon dioxide with an impurity content of metals Fe, Ni, Cr, Co at a level of 1-3-10 masses. /about. Capacity А 3 kg / h, decomposition duration T 8 hours. Particle size of the loaded product is up to 1500 µm. The temperature of the furnace and the loaded product is brought to the working temperature (800 ° С) with stirring, at which the modification of amorphous silicon dioxide is obtained. Then in the initial zone of the furnace begin to apply to the mobile dispersed layer with a dosage of 15 kg / h orthosilicic acid sol containing 80% moisture. The content of impurities in the ash in terms of the target product is at the level of 7-10®-2-10 mass. % At the same time from the final zone of the furnace they begin to release the finished product. In the continuous mode, 3 kg / h of uniform silica with a particle size of not more than 1500 microns is obtained from the furnace. The impurity content of the obtained target product is at the level of not more than 1 to 3 to 10 mass. % The results remain stable even after the target product has been produced in an amount several times higher than the preloaded quantity.

Example 2. A rotary, uyus horizontal electric furnace is loaded with dispersed alumina of high purity with particles up to 2000 µm, G is 210 kg (3 AT), where A is 10 kg / h of the target product, and T is 7 hours. The impurity content of the elements (metals) is em 10 mass. % With

When the temperature reaches 600 ° C, a continuous feed of the suspension with a dosage of 61.2 kg / h containing 75% water is started in the initial zone of the furnace. The content of impurities in the suspension, in terms of alumina, is at a level of 4–3 10 mass. % 10 kg / h of the desired product with particles up to 2000 μm and the impurity content of 6-10-6-5-10-5 mass are obtained from the furnace. %

Example 3. When producing high purity alumina in example 2, the same target product is preloaded in the amount of G 10 AT 10 10-7 700 kg. When the same temperature is reached (600 ° C, a suspension of aluminum hydroxide containing 20% water and the same amount of impurities in terms of alumina (4-10® -3-10 wt.%) Begins to be supplied to the initial zone of the furnace. aluminum hydroxide slurry is 19.0 kg.

10 kg / h of the target product of the same quality in terms of purity and dispersion is also obtained from the furnace.

Example 4. When receiving high-purity alumina, dispersed alumina with particles up to 2000 µm is loaded into the furnace in the amount of 6 AT 6-10 X X7 420 kg. The impurity content is as in Example 2, 6 10 -5%. When the temperature reaches 600 ° C, an initial feed of the aluminum hydroxide slurry with a wax content of 90% and with the same amount of primes as in example 1 6-10 - 5x begins

X IDS masses. % Particle size up to 2000 microns.

Example 5. G 6 AT 144 kg of dispersed magnesia with particles up to 2000 microns with the content of metals Fe, Cu, Ni, Cr, Co S-IO-3 lOS masses is loaded into a rotary horizontal furnace. % Capacity A is 3 kg / h and decomposition time T is 8 hours. The furnace with the loaded product is heated to the decomposition temperature (600 ° C), after which a continuous supply of magnesium carbonate suspension containing water with limited impurities of metals Fe, Cu, Ni, Cr, Co at the level of 6-10 -2-10 masses. % in terms of magnesium oxide. Suspension is served in the amount of 13.3 kg / h. From the kiln continuously receive, maintaining a constant level of the dispersed layer, the target product in the amount of 3 kg / h with the impurity content of these elements at the level of 8 10 -3 X X 105 masses. /about. Particle size up to 2000 microns.

Example 6. Dispersed titanium dioxide with particles up to 2000 µm in an amount of 8 AT 8-5-6 240 kg with the impurity content of elements I -5 10 masses is loaded into a horizontal continuous furnace. % When the temperature reaches 500 ° C, a suspension of titanium hydroxide Ti (OH) i with a water content of not the amount of impurities at the level of 8-10 - .2-10 mass. % Suspension is served in the amount of 10.35 kg / h.

From kilns receive 5 kg / h of the target product with the content of impurities in the mass, / o with particles up to 2000 microns.

Example 7. Lead red lead PbjO4 with particles of a micron in the amount of 5 AT 5-20-4 400 kg with the impurity content of elements 8-10 -3-10 mass is loaded into a horizontal continuous furnace. When reaching 500 ° C, lead suspension carbonate containing 40% of water and with the amount of impurities at the level of 5-10 -1-10 wt. % The suspension is served at 42 kg / h. From the furnace, 20 kg / h of red lead are obtained, with an impurity content in the range of 8-10 -3-10 wt.%. Part size up to .1500 microns.

The possibility of obtaining in this method of dispersed oxides of elements in the process of thermal decomposition without the use of drying and grinding processes also provides a significantly lower content of impurities in the oxides produced.

This makes it possible to master new types of equipment and products, to improve the technical characteristics of products in electronic, semiconductor, optical and other fields of technology, where there is an acute need for an all-high-purity oxide element, and an all-round increase in their frequency plays a crucial role.

As a result of the elimination of drying, grinding, intermediate transport, this method also provides significant savings in energy and labor costs.

Claims (2)

1. Method of continuous production of elements of elements by thermal decomposition of the compounds of the corresponding elements, characterized in that, c. to increase the dispersion of the product and reduce the contents. no impurities in it, using the original compounds with a moisture content of 20-90%,  which are fed to the heated layer of the target product, taken in an amount calculated by the formula G 3-10 AT, where G is the amount of the target product, A is the process productivity per unit of time and T is J duration of the process. 2. A method according to claim 1, characterized in that the starting compound is supplied when the decomposition temperature of the compound is reached in the layer. Sources of information 0 taken into account in the examination 1. Patent of the USSR No. 464991, cl. From 01 To 13/14, 1972. 2. The patent of Germany No. 1767511, cl. C 01 F 7/44, 1976 (prototype).