RU2293133C2 - Method for producing germanium concentrate from coals - Google Patents

Abstract

FIELD: chemical and metallurgical industry branches, possibly producing germanium concentrate from coals.

SUBSTANCE: method comprises steps of subjecting coal in the form of coal layers to heat treatment in shaft type apparatus by supplying air to lower part of said apparatus and heating upper layer of coal till its burning temperature. After creating stable burning zone heating of upper zone is interrupted and temperature in burning layer is kept no less than 1000°C and temperature in calcined layer is kept no less than 700°C. Motion rate of burning zone is sustained due to controlling air flow rate at specific feed of air 250 -300 nm³/m² h. When burning zone achieves lower part of apparatus air feed is interrupted.

EFFECT: increased degree of germanium extraction from coals without pyro-metallurgical concentration of germanium concentrate.

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Description

The invention relates to the technology of organic compounds and metallurgy and can be used to obtain a germanium concentrate.

A known method of producing a germanium concentrate from fossil coals by collecting enriched germanium compounds of fly ash generated by burning these coals in power boilers (Metallurgy of dispersed and light rare metals. M.A. Kotenkova, O.E.Krein. Moscow, 1977, p. 21).

The disadvantage of this method is the low degree of extraction of germanium (approximately 45%) from coal and the low content of germanium compounds in fly ash (up to 5 kg / t), which requires pyrometallurgical enrichment to obtain a germanium concentrate suitable for the extraction of germanium. A significant part of the germanium compounds is contained in the slag, at concentrations insufficient for its cost-effective recovery.

The closest in technical essence and the achieved result is a method for producing a germanium concentrate from volatile dust, tar and tar resin by-product coke plants in gas generating plants (Chemistry of Germany. I.V. Tananaev, M.Ya. Shpirt. Moscow, 1967, p. 366) .

The disadvantages of this method are the low degree of extraction (20-30% for coking and up to 75% for coal gasification) of germanium from coal, low germanium content, which requires energy-intensive and multi-stage pyrometallurgical and reagent treatment to obtain germanium concentrate, as well as environmental hazard and toxicity of tarry substances and tar waters formed during coking and gasification of coal.

The invention solves the problem of increasing the degree of extraction of germanium from fossil coals.

The technical result when using the invention is to obtain a germanium concentrate without pyrometallurgical enrichment and exhaust gases, for example, to generate electrical energy.

It is achieved by a method of producing germanium concentrate from fossil coals, including heat treatment of fossilized germanium-containing coal, according to which heat treatment of coal in the form of layers is carried out in a mine-type apparatus by supplying air to the lower part of the apparatus and heating the upper coal layer to a combustion temperature, after creating a stable combustion zone, heating the upper zone is stopped, and the temperature in the burning layer is not lower than 1000 ° C and in the cinder layer not lower than 700 ° C and the speed of the combustion zone is supported by regulation air flow when its specific supply of 250-300 nm ³ / m ² h, and when reaching the combustion zone of the lower part of the apparatus, the air supply is stopped.

It is known that the thermal conductivity of a layer of carbon-containing material depends on its fractional composition, degree of metamorphism, and humidity. If in this case the convective removal of thermal energy from the layer into the air is less than the heat flux entering the layer due to the heat conduction mechanism, then the layer backfill will be heated against the air flow - a “heat wave” will form. That is, the layer sequentially goes through the stages of heating, drying and evolution of volatiles (pyrolysis). Pyrolysis products containing, inter alia, combustible components such as carbon monoxide, hydrogen, liquid and gaseous hydrocarbons, together with solid carbon react with atmospheric oxygen to form a combustion front. The temperature in it reaches 750-1200 ° C, and all the oxygen in the air reacts in this zone. Behind the combustion front there is a recovery zone in which the combustion products (carbon dioxide and water vapor) are converted into combustible components of associated gas by reduction on a carbon surface by the following reactions:

C + CO ₂ → 2CO,

C + H ₂ O → H ₂ + CO,

C + 2H ₂ → CH ₄ ,

and partial reduction of germanium dioxide to oxide:

GeO ₂ + CO → GeO + CO ₂ ,

GeO ₂ + H ₂ → GeO + H ₂ O.

The necessary reducing atmosphere is created by a specific ratio of CO: CO ₂ . Since the temperature in the apparatus is higher than 700 ° C, germanium oxide is removed from the apparatus in a volatile form along with the exhaust gas and fly ash.

When the specific air supply to the apparatus is 250-300 nm ³ / m ² h, the linear velocity of the exhaust gas is 0.6-0.75 m / s, at this speed the removal of fly ash is negligible and does not exceed 200 mg / nm ³ . Further, the exhaust gases are cooled to a temperature of 100-200 ° C and fed to the filter, where the condensed oxide and germanium dioxide are separated together with fly ash.

The degree of germanium extraction in the described method is 80-90%, and the concentration of germanium compounds in the solid residue removed from the filter is 50%, which allows the use of the solid residue as a germanium concentrate without pyrometallurgical enrichment.

In the described method, the fossil coal pyrolysis zone is located in front of the high-temperature oxidation zone along the blast, and all hydrocarbon compounds formed during the thermal decomposition of coal, including tarry substances, are broken down and oxidized in the high-temperature zone. The flue gases consist of carbon monoxide and dioxide, hydrogen, water vapor, nitrogen and a small amount of methane. The absence of tarry substances, tar resin, benzopyrene and other toxic substances ensures the environmental safety of production, and the exhaust gases after the filter, without additional purification, can be used as an energy carrier for the generation of thermal and electric energy, as well as in various technological processes.

Example 1

Out of 1 ton of grade D coal with a calorific value of 4200 kcal / kg and a germanium content of 404 g / t, 740 g of germanium concentrate is produced with a germanium content of 47% (i.e., 86% germanium recovery). The specific yield of combustible gas with a calorific value of 4.9 MJ / nm ³ is 3600 nm ³ / t. Gas is suitable for generating electrical and thermal energy.

Example 2

One ton of coal of a certain composition (granular) is loaded into a bed apparatus. Air is supplied to the lower part of the apparatus, and the necessary temperature is created at the upper part due to electric spirals for starting combustion of the upper layer of coal for about 30 minutes. After obtaining a stable coal combustion zone, the heating of the spirals is turned off. Further, the temperature and speed of the combustion zone are regulated by the air flow from below. The temperature in the burning layer is maintained not lower than 1000 ° C, and the temperature in the cinder layer is not lower than 700 ° C. When the combustion zone reaches the bottom of the layered apparatus, the air supply is stopped - the mode is exhausted.

Using this technology, for example, from 1 ton of grade D coal with a calorific value of 4200 kcal / kg and a germanium content of 404 g / t, 740 g of germanium concentrate with a germanium content of 47% is obtained (i.e., the germanium recovery rate is 86%). The specific yield of combustible gas with a calorific value of 4.9 MJ / nm ³ is 3600 nm ³ / t. Gas is suitable for generating electrical and thermal energy.

Claims (1)

A method of producing germanium concentrate from fossil coals, including heat treatment of fossilized germanium-containing coal, characterized in that the heat treatment of coal in the form of layers is carried out in a mine-type apparatus by supplying air to the lower part of the apparatus and heating the upper coal layer to a combustion temperature, after creating a stable combustion zone, heating the upper zone is stopped, and the temperature in the burning layer is not lower than 1000 ° C and in the cinder layer not lower than 700 ° C and the speed of the combustion zone is maintained by controlling the air flow and when a specific filing 250-300 Nm ³ (m ² h) and on reaching the combustion zone of the lower part of the air supply apparatus is stopped.