RU2222626C1 - Method for extracting rhenium and other elements - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: proposed method used for extracting scattered and rare elements, noble and nonferrous metals from heavily watered natural gases, such as volcanic fumarole and industrial gases, includes accumulation of volcanic gas, its cooling, and capture of compounds obtained. In the process volcanic gas is accumulated at pressure within storage vessel between 20 and 100 Pa and cooled down to 300 400 C with rhenium and other elements being concentrated. Electric precipitator or set of precipitators is used for catching and separating solid compounds from gas phase, gas temperature at output of precipitator or set of precipitators being maintained between 200 and 250 C. Gas temperature is maintained within electric precipitator by evaporating water supplied in sprays to gas conduit upstream of precipitator. Volcanic gas is accumulated in vessel made of corrosion-resistant materials. This comprehensive method enables separation of components from gases with high degree of extraction, resultant concentrate being suited to recovery of elements using pyrohydrometallurgical process. EFFECT: enhanced content of valuable elements in concentrate obtained. 3 cl, 1 tbl

Description

 The invention can be used to highlight scattered and rare elements, noble and non-ferrous metals from heavily flooded natural volcanic and industrial gases.

A known method of trapping rhenium from exhaust calcining gases obtained by the oxidation of molybdenum and copper concentrates [1]. According to this method, the gases after purification in a hot cyclone are bubbled through wet absorbers (aqueous, acidic or alkaline) of various designs. Up to 96% of the rhenium coming from the gases is captured. However, for the extraction of rhenium and other elements from gases with a high moisture content, in particular from volcanic gases, this capture method cannot be applied, because due to the low concentrations of valuable components in gases, their concentrations in the pulp (solution) will also be low. insufficient for cost-effective industrial recovery. In addition, the use of the wet method of capturing compounds of valuable elements in relation to volcanic, for example fumarole gases containing 92-98% water vapor, will lead to high costs for cooling these gases and condensation of the water contained in them. For example, to remove heat from the wet capture apparatus when it is cooled through the wall of one ton of volcanic gases containing 95% water with a temperature of 200 ^° C to 90 ^° C, approximately 8.0 tons of cooling water with a temperature of 20 ^° C will be required.

Closest to the invention in technical essence is a method for the extraction of rhenium and other metals, which consists in concentrating rhenium and other metals contained in volcanic gases by depositing their sulfides from the gas phase in a filter layer consisting of carrier particles [2]. According to this method, volcanic gases having a temperature of 600 ^° C or lower (gases with a temperature of more than 600 ^° C are pre-cooled to 500-550 ^° C) are passed through a filter layer consisting of carrier particles for 1-30 days, followed by replacement the carrier, and the spent carrier containing sulfides of rhenium and other metals is sent to hydrometallurgical processing. It is proposed to use mineral wool, activated carbon, granular alumina, carbon fabric or, preferably, natural zeolite of a fraction of 1-8 mm as a carrier.

The disadvantages of this method are as follows:
1. When using it, selective capture of only rhenium sulfide and compounds of some other elements occurs. The ratio in the source gas and the discharged carrier is almost the same for rhenium, cadmium, antimony and bismuth. At the same time, in comparison with the initial gas, the carrier is twice as depleted (with respect to rhenium) in silver - by half, in Germany - by 5.4 times, in gold and indium - by 30-35 times.

 2. In the process of collecting, there is a decrease in the porosity of the carrier layer, both due to the crystals formed, and mechanical dust collection. This leads to an increase in the resistance of the layer and, as a consequence, a decrease in gas consumption, a change in the temperature regime and the need for frequent replacement of the layer (once every 1-30 days). Thus, the process is practically uncontrollable, and the degree of capture of valuable elements is sharply reduced due to periods of media replacement.

3. Aggressive medium (water in combination with acid-forming gases - НСl, HF, SO ₂ ) does not allow counting on effective mechanization of the process with frequent replacement of the carrier due to severe corrosion of the mechanisms.

 4. The use of media dramatically increases the volume of transported and processed material.

 These disadvantages are eliminated when using the proposed method.

The task to which the proposed method is directed is to achieve an almost complete and integrated extraction of valuable elements from volcanic and similar gases into a rich dehydrated collective concentrate. To solve it, it is necessary
1. Provide conditions for the transition to a liquid and solid state of compounds of these elements contained in the gas. As can be seen from the attached table, this is achieved by cooling the gas to a temperature of 400 ^o C (with the exception of "Tl ₂ S ₂ , which becomes solid at 260 ^o C).

2. To prevent condensation of water, the main component of volcanic gas, ie, the separation of the collective concentrate from the gas phase to produce at temperatures above 100 ^o C.

3. To prevent the release of volcanic gas from elemental sulfur by the reaction proceeding at a temperature of 250 ^o C [4] and below
2H ₂ S + SO ₂ = 2H ₂ O + 3S.

 Due to the relatively high content of hydrogen sulfide and sulfur dioxide in volcanic gas (example), the amount of liquid sulfur emitted can increase the amount of rare-metal concentrate by an order of magnitude, thereby worsening its quality. At the same time, both the operation of the concentrate capture system and the processing of the latter will become significantly more complicated. The technical result, which is achieved by the proposed method, is the allocation of volcanic gas 90-96% of the rhenium contained in it and other valuable elements in the form of a rich collective concentrate.

The technical result is achieved by the fact that the method includes collecting volcanic gas, cooling and capturing the obtained compounds, moreover, the volcanic gas is collected at a pressure in the collector of 20-100 Pa, cooling is carried out to a temperature of 300-400 ^o C with concentration of rhenium compounds and other elements, and collection with separation of the formed solid compounds from the gas phase is carried out in an electrostatic precipitator or an electrostatic precipitator system while maintaining the gas temperature at the outlet of the electrostatic precipitator or an electrostatic precipitator system at a level of 200 -250 ^o C. The temperature of the gas in the electrostatic precipitator is maintained by evaporation of the water supplied in atomized form to the duct in front of the electrostatic precipitator. Volcanic gas is collected in a device made of corrosion-resistant materials.

Volcanic gas is collected using a special device under conditions that prevent it from mixing with air. This excludes the possibility of oxidation of rhenium sulfide to produce oxide more difficult to condense from the gas phase [1], and also prevents the condensation of water with the dissolution of acid-forming gases (Hcl, HF, SO ₂ ) and the formation of an extremely corrosive liquid in it.

Partial cooling of the collected gas occurs due to natural heat loss in the lined (for corrosion protection) duct, through which gas is transported from the collector to the electrostatic precipitator. The amount of heat loss during installation can be controlled by the thickness of the thermal insulation of the gas duct, and it should be designed for the most severe (winter) environmental conditions. The final (accurate) adjustment of the temperature to a predetermined value according to the proposed method is produced by water supplied to the gas duct through a nozzle with mechanical spraying. Water consumption is minimal due to the rational use of high heat of vaporization. For example, ~ 0.06 kg of water is consumed for cooling 1 kg of water vapor from 500 to 400 ^o С and due to an increase in the volume of processed gas by 6-7% (adjusted for other components of volcanic gas), there is no need to build complex and expensive heat exchangers .

 Determines the normal operation of the last electrostatic precipitator, the gas temperature at the outlet of the apparatus, almost equal to the temperature at which the formation of elemental sulfur from sulfur dioxide and hydrogen sulfide begins and significantly exceeds the condensation temperature of water. A higher gas temperature at the inlet to the electrostatic precipitator (electrostatic precipitator system) provides a heat reserve to compensate for heat losses in the process of capturing a marketable product. Work in the specified conditions of such highly efficient devices as an electrostatic precipitator ensures the completeness and complexity of collecting valuable components (up to 90-96%).

 Collective concentrate separated from volcanic gas is collected in a bunker, unloaded and sent for processing by pyrohydrometallurgical methods.

 The gas after separation of the concentrate containing compounds of rare and trace elements, noble and non-ferrous metals, as well as their attendant elements, is sent to a wet capture system to separate sulfur, fluorine compounds and dust not captured in the electrostatic precipitator.

 Example.

We have volcanic gas composition, mol. %: H ₂ O 92-98; H ₂ 0.002-1.3; CO ₂ 0.5-2.5; WITH up to 0.2; SO ₂ 0.1-2.3; H ₂ S 0.1-0.7; HCl 0.01-0.8; HF up to 0.08; N ₂ 0.06-0.6; O ₂ to 0.15; Ar up to 0.005; CH ₄ to 0.21; containing, g / t: Re 0.8; Ge 0.6; Ag 0.08; Au 0.2; In 0.8; Bi 0.5; Tl 0.12; Zn 70; Cd 0.3; Sb 1.5; Ni 40; C 5.8; Mo 0.12. The gas temperature is 500-600 ^o C, the pressure in the collector is 60 Pa.

Before feeding the electrostatic precipitator, volcanic gas is cooled to 400 ^o C. The gas temperature at the outlet of the electrostatic precipitator is 250 ^o C.

 The total content of sulfides and other compounds that become solid when the specified gas is cooled to the working temperature of the electrostatic precipitator and trapped in it is approximately 0.9 kg per ton of volcanic gas.

 The product discharged from the electrostatic precipitator contains, g / t: Re 890; Ge 670; Ag 89; Au 220; In 890; Bi 550; Tl 130; Cd 330; Zn 75000; Sb 1700; Ni 44000; From 6400; Mo 130.

 The resulting concentrate compared with the concentrate obtained by the method adopted for the prototype, has a significantly higher content of valuable elements accompanying rhenium in volcanic gas. It is suitable for the extraction of rhenium and other elements by pyrohydrometallurgical methods.

 The technical efficiency of the proposed method for the extraction of rhenium and other elements from volcanic gas lies in the fact that when using the proposed method it is possible and economically feasible to comprehensively extract valuable components from volcanic gas, a new raw material source of primarily scattered elements. The proposed method allows for the almost complete selection in a complex concentrate of scattered and noble elements, rare and non-ferrous metals in a form suitable for further pyrohydrometallurgical processing.

SOURCES OF INFORMATION
1. Lebedev K.B. Rhenium. - M .: Metallurgizdat. 1959. 102 p.

 2. Shaderman F.I., Kremenetsky A.A., Shteinberg G.S. The method of extraction of rhenium and other metals. RF patent 2159296, IPC С 22 В 61/00, В 01 D 7/02, decl. 06/10/1999, publ. 11/20/2000. Bull. 32.

 3. Goronovsky I.T., Nazarenko Yu.P., Nekryach E.F. A quick reference to chemistry. - Kiev: Naukova Dumka. 1974. 992 p.

 4. Brief chemical encyclopedia. - M .: Soviet Encyclopedia. 1965.V.4. 1182 p.

Claims (3)

1. The method of extraction of rhenium and other elements, including the collection of volcanic gas, its cooling and capture of the obtained compounds, characterized in that the volcanic gas is collected at a pressure in the collector of 20-100 Pa, cooling is carried out to a temperature of 300-400 ° C with concentration of the compounds rhenium and other elements, and collection with separation of the formed solid compounds from the gas phase is carried out in an electrostatic precipitator or electrostatic precipitator system while maintaining the gas temperature at the outlet of the electrostatic precipitator or electrostatic precipitator system at the level of 200-250 ° C. 2. The method according to claim 1, characterized in that the gas temperature in the electrostatic precipitator is maintained by evaporation of the water supplied in atomized form to the gas duct in front of the electrostatic precipitator. 3. The method according to claim 1, characterized in that the volcanic gas is collected in a device made of corrosion-resistant materials.

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