DE102008006246A1 - Process to produce mercury sulfide by heating mercury and sulfur at reduced pressure with conditioning agent - Google Patents

Abstract

In a process to produce mercury sulfide for subsequent safe disposal, the mercury elementary mercury is mixed with elementary sulfur or a sulfur compound at a temperature greater than 50[deg] C and at reduced pressure. Further claimed is a commensurate assembly in which the mixing process takes place at a temperature of above 150[deg] C and preferably at the melting point of mercury. The ingredients are present in a stoichiometric ratio of between 0.19: 1 and 0.23: 1 in a gas-tight chamber devoid of oxygen and flushed by inert gas. The mixing process continues for 30 to 60 minutes and processes between 10 and 10,000 litres per batch.

Description

The The invention is directed to a method and an apparatus for manufacturing of mercury sulfide for subsequent disposal, wherein the mercury sulfide during a reaction process in a reactor from a reaction of elemental mercury and an elemental sulfur and / or a sulfur compound resulting addition material.

mercury is due to its special physical properties in many technological applications and in industrial production used. Here is in particular the Chloralkalieelektrolyse to To call extraction of chlorine. In addition to a variety of positive Properties is mercury but also a toxic hazardous substance, in particular due to its already at room temperature comparatively high vapor pressure represents a danger to humans and the environment. Numerous accidents and almost irreversible environmental damage In the past, mercury has become dubious popularity helped.

In front This background is today in many areas mercury or entire production processes substituted to the use of Mercury and thus mercury emissions as much as possible to reduce. The reduced demand leads to a reduction up to cessation of production of primary mercury at the known production sites. Already for many Years ago, secondary mercury goes out in recycling plants Reclaimed waste and as an alternative to Primary mercury offered on the market. Very large quantities Secondary mercury will in future with the worldwide conversion of existing chlorine production from the amalgam process released for the membrane method. Permanently it will not be possible the mercury released from these installations in other environmentally sound Use applications. Against this background, it becomes necessary for elemental mercury an environmentally sound, final Disposal possibility to provide.

A Possibility of transformation of elemental mercury in a stabilized mercury compound is in the production of mercury sulphide (cinnabar). Mercury sulphide is a stable one or stabilized compound, due to their known properties (non-toxic, chemically stable, even under aggressive conditions) permitting permanent and safe storage of mercury. Incidentally, it is also possible in principle Produce mercury sulfide using sulfur compounds.

From the US-A-5,034,054 A method for producing a stabilized mercury compound for subsequent disposal is already known. In this case, mercury is bound in the form of an amalgam in conjunction with copper, zinc or nickel as an additional material or as mercury sulfide in combination with sulfur as an additive and then disposed of in an environmentally sound manner. In the known method, the addition material is added with the mercury in a stoichiometric ratio of at least 1: 1 and preferably 3: 1. The mixing process is carried out in a mixing device at room temperature and ambient pressure at discontinuous feeding of the mixing device. A disadvantage of the known method is that the addition material must be added in a strong superstoichiometric ratio to the mercury in order to ensure a sufficient reaction of the mercury to the mercury compound. Another disadvantage of the known method is that in view of the strong superstoichiometric excess of the addition material which is added in powder form, in the mixing process aerosols, that is the smallest sedimenting in the air addition material particles can arise. The batchwise operation of the mixing device leads in the known method to high costs and comparatively low production quantities of mercury sulphide.

task The present invention is now a method and an apparatus to provide the type mentioned above, with the mercury sulfide in a simple and cost-effective manner and can be produced as possible without environmental impact.

These Task is characterized by a method of the type mentioned by solved that the reactor continuously with the Mercury and the addition material is charged, the mercury and heated the addition material in the reactor and into a gaseous Condition are transferred and the reaction between the mercury and the feedstock in the gas phase he follows.

The invention relates to a continuous process for the immobilization of mercury by reaction with sulfur to mercury sulfide, wherein mercury and sulfur are continuously converted by means of a suitable apparatus in the gas phase and a continuous gas phase reaction between mercury and sulfur is achieved. The continuous production of mercury sulfide leads compared to that of US-A-5,034,054 known methods for a cost saving and a process simplification. The method according to the invention is preferably designed such that the mercury sulphide produced meets the requirements for subsequent disposal, preferably for disposal underground, corresponds.

In connection with the invention it has been recognized that the highly superstoichiometric addition of the addition material according to the US-A-5,034,054 Therefore, it is necessary that the reaction of sulfur with mercury can only occur on the surface of the solid state sulfur particles. In order to allow a complete reaction of the sulfur with the mercury, a high excess of sulfur is necessary in this known solid-liquid reaction. In the method according to the invention, however, the mercury and the addition material in the reactor are converted into the gaseous state, wherein both reaction components react with one another in the gaseous state. This greatly increases the reactivity of mercury and facilitates the formation of mercury sulfide.

Device is according to to solve the above object, a preferably indirectly heated reactor for transfer of elemental mercury and elemental sulfur and / or a sulfur compound containing addition material in the gaseous Condition provided, the reactor via an appropriate trained feeding device continuously with the mercury and the addition material can be loaded. In the reactor can it is a preferably upright tubular reactor, the high conversion rates of gaseous components guaranteed. Incidentally, the indirect heating of the reactor leads to a procedural simplification.

in the Related to the continuous production of mercury sulphide is further provided that in the reaction in the reactor available mercury sulfide continuously vaporous is discharged from the reactor. The operating temperature in the reactor is preferably above the boiling point of mercury sulphide or above the evaporation temperature, so that the mercury sulphide formed is not within the reactor condenses or resublimates. The operating temperature in the reactor should therefore preferably be above about 580 °, however, it may also be higher to allow condensation or resublimation of mercury sulfide safely exclude can. If the reactor is operated under reduced pressure, The operating temperature can also be reduced accordingly.

Of the Operation of the reactor at temperatures in the range above the The boiling point of mercury sulfide leads by the way to ensure that the starting materials after entry into the reactor converted very quickly into the gaseous phase become. This can be the necessary Reduce residence time in the reactor and reduce the production volume of Increase mercury sulfide accordingly.

Of the Reactor can with a preferably homogenized mixture of liquid mercury and powdery addition material be charged. This allows a procedurally simple continuous feed of the reactor with the starting materials. It is understood that a loading device is provided must be, for the continuous feed of the reactor is formed with the homogenized mixture. in principle may also be provided a dosing, with mercury and Addition material to the reactor from storage tanks in the desired mixing ratio be supplied separately.

In particular, when carrying out the method according to the invention in the aforementioned temperature range and / or in the vacuum operation, it is possible to add the starting materials or starting materials in the stoichiometric or a slightly more than stoichiometric ratio. The stoichiometric ratio of elemental sulfur to mercury is 0.16: 1. With such a ratio, there is an ideal conversion of the starting materials to mercury sulfide. In the case of incomplete conversion, the upper limit is 0.5: 1 and thus still 100% below the lower limit of the mixing ratio US-A-5,034,054 is called. Preferably, the ratio of elemental sulfur to mercury is between 0.18: 1 to 0.32: 1, and more preferably between 0.19: 1 and 0.23: 1.

The Design of the reactor and the streams should be be chosen so that the computational residence time of mercury and addition material in the reactor for at least one second to 6 seconds, preferably less than four seconds. As a result, sufficient sales in the gas phase reaction between the mercury and the added material.

Preferably the reactor and also the others involved in the production of mercury sulphide Devices in the device according to the invention operated gas-tight to make it in continuous production of mercury sulphide does not lead to the escape of mercury sulphide can get into the area. This is an environmentally sound production of mercury sulphide from the starting materials possible.

The reactor can be subjected to a low vacuum by means of a vacuum pump or a vacuum blower in order to ensure operational safety and the escape of mercury To be able to exclude sulfide from the reactor. It is understood that the operation under low negative pressure relates to all the devices of the device according to the invention, which are traversed by gaseous mercury sulfide.

vacuum in the sense of the invention refers to any pressure below the ambient pressure to to the vacuum. Sufficient are already low negative pressures of 0.05 bar, resulting in an ambient pressure of 1 bar absolute pressures corresponds to 0.95 bar. Carrying out the gas phase reaction In the negative pressure causes the boiling point of mercury decreases accordingly and even at lower temperatures a high Concentration of mercury in gaseous form in the reactor is achieved, whereby a high conversion rate with less energy is guaranteed.

Further is provided in the method according to the invention, that the vaporous mercury sulphide after the Removing from the reactor with a liquid or vaporous cooling medium abruptly at least until a solid state is reached, preferably one Temperature of less than 50 ° C, cooled and together with the cooling medium of a solid-liquid separation is subjected. The cooling medium may be water act, wherein for cooling the mercury sulfide a Quench and / or a water jet pump can be provided. So that it does not lead to an unwanted condensation or resublimation of Mercury sulphide comes before the sudden cooling, can be a heatable conduit for the mercury sulfide between the reactor and the quench and / or the water jet pump be provided. With operation of the quench or the water jet pump In normal operation, there is a sufficient pressure gradient to the reactor so that there is the possibility the system without vacuum pump or vacuum fan at low To operate negative pressure without the escape of mercury sulfide into the environment must be feared.

Of the Quench or the water jet pump can be cooled with Be fed with water, causing a sudden cooling of the vaporous mercury sulfide, the subsequently together with the water of a solid-liquid separation stage is fed to the cooled mercury sulfide separate from the cooling medium. The cooling medium can be circulated, resulting in a saving of Operating costs leads.

The solid-liquid separation of solid mercury sulfide and liquid cooling medium can be done by gravity separation in a sedimentation tank and / or by centrifugal separation in a centrifuge. The high density of mercury sulfide of 8.1 g / cm ³ allows a simple and cost-effective separation of mercury sulfide from the cooling or washing water. The solid mercury sulfide thus obtained can be pressed following the solid-liquid separation and optionally dried. In this connection, a pressing device, preferably a filter press, can be provided, wherein the filter cake of mercury sulphide obtainable in this way can subsequently be dried in a vacuum mixer and / or a drying oven.

It It is expressly stated that all mentioned above and specified in the claims Area information all, within the area concerned including intermediate intervals and individual values including include any decimal places, even if these intermediate intervals and individual values are not specified in detail.

The single figure shows a schematic representation of a device for the production of mercury sulfide for subsequent Disposal. With reference to the drawing below, the inventive Method described. However, it should be noted that the Invention is not limited to the illustrated embodiment is.

In the single figure is a device 1 for the production of mercuric sulfide (HgS) from elemental mercury (Hg) and elemental sulfur (S) for final environmentally sound disposal. The mercury is preferably secondary mercury. The device 1 has a reactor 2 formed as an upstanding tubular reactor and is indirectly heated and is formed for the transfer of elemental mercury and an elemental sulfur and / or sulfur compound containing addition material in the gaseous state. Not shown in detail that the reactor 2 a charging device comprising a continuous feed of the reactor 2 with the mercury and the addition material from a storage container 3 allows. The original container 3 contains a previously mixed and largely homogenized mixture of sulfur and mercury.

In the reactor 2 is at an operating temperature which is above the boiling or evaporation temperature of mercury sulfide, the continu ously the reactor 2 supplied starting mixture of mercury and elemental sulfur in the gaseous state. This is followed by a continuous gas phase reaction between the present in the gaseous state feedstocks, wherein the thus obtained vaporous mercury sulfide in a computational dwell time of the starting materials in the reactor 2 from more than one second to preferably less than four seconds continuously from the reactor 2 dissipated and a quench 4 is supplied. An exemplary illustrated line 5 between the reactor 2 and the quench 4 is heatable to the condensation or resublimation of mercury sulfide in the line 5 to prevent.

In the gas phase reaction in the reactor 2 Red crystalline mercury sulphide is obtained. Red mercury sulphide is insoluble in water, acids (except aqua regia) and alkalis, stable and non-toxic. Therefore, red mercury sulfide is suitable for permanent disposal.

The quench 4 is fed with circulated cooling water, so that it in quench 4 comes to a sudden cooling of the mercury sulfide to the range of the solid phase of mercury sulfide. Preferably, the mercury sulfide is cooled to a temperature between 25 ° C and 50 ° C. Subsequently, the solid mercury sulfide thus obtained is fed together with the cooling water of a solid-liquid separation stage, wherein in a centrifuge 6 the solid mercury sulfide is separated from the liquid cooling water. The cooling water then becomes a quench 4 returned, with an intermediate cooling of the cooling water can be provided.

Following the solid-liquid separation, the mercury sulfide becomes a filter press 7 fed. The filter cake thus produced can be subsequently dried in a drying device not shown in detail and is then stored in disposal containers 8th filled.

Otherwise, there is a vacuum pump 9 provided to detect vaporous mercury sulfide portions and an activated carbon filter 10 supply. The activated carbon filter 10 Passing gas stream can then be discharged into the environment.

1

contraption

2

reactor

3

storage container

4

quench

5

management

6

centrifuge

7

filter Press

8th

storage containers

9

vacuum pump

10

Activated carbon filter

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 5034054 A [0005, 0008, 0009, 0014]

Claims (20)

A process for the production of mercury sulphide for subsequent disposal, wherein the mercury sulphide during a reaction in a reactor ( 2 ) resulting from a reaction of elemental mercury with an elemental sulfur and / or sulfur compound-containing addition material, characterized in that the reactor ( 2 ) is continuously charged with the mercury and the feedstock, the mercury and the feedstock in the reactor ( 2 ) and converted to a gaseous state, and wherein the reaction between the mercury and the feedstock is in the gaseous phase. Process according to claim 1, characterized in that in the reaction in the reactor ( 2 ) mercury sulfide continuously from the reactor ( 2 ) is discharged. Process according to Claim 1 or 2, characterized in that the reactor ( 2 ) is operated at an operating temperature above the boiling point of mercury sulfide, in particular at an operating temperature above greater than 500 ° C, more particularly above 580 ° C. Process according to one of the preceding claims, characterized in that the reactor ( 2 ) is charged with a preferably homogenized mixture of mercury and addition material. Method according to one of the preceding claims, characterized in that the addition material and the mercury in a stoichiometric or a slightly more than stoichiometric ratio, preferably in a stoichiometric ratio of 0.16: 1 to 0.5: 1, in particular between 0.18: 1 to 0.32: 1, and more preferably between 0.19: 1 and 0.23: 1, to the reactor ( 2 ). Method according to one of the preceding claims, characterized in that the computational residence time of the mercury and of the addition material in the reactor ( 2 ) is at least 1 s, preferably between 1 to 6 s, more preferably less than 4 s. Process according to one of the preceding claims, characterized in that the reactor ( 2 ) is operated gas-tight. Process according to one of the preceding claims, characterized in that the reaction in the reactor ( 2 ) is carried out under reduced pressure. Process according to one of the preceding claims, characterized in that the mercury sulphide, after being discharged from the reactor ( 2 ) is abruptly cooled with a liquid cooling medium at least until it reaches a solid state, preferably to a temperature of less than 50 ° C. Method according to one of the preceding claims, characterized in that the cooled mercury sulfide by solid-liquid separation of the cooling medium is separated. Method according to one of the preceding claims, characterized in that the cooling medium in Circulation is performed. Method according to one of the preceding claims, characterized in that the solid-liquid separation by gravity separation and / or centrifugal separation takes place. Method according to one of the preceding claims, characterized in that the mercury sulfide after the solid-liquid separation pressed and optionally is dried. Contraption ( 1 ) for the production of mercury sulfide for subsequent disposal for carrying out the method according to one of the preceding claims, with a preferably indirectly heated reactor ( 2 ) for the transfer of elemental mercury and an elemental sulfur and / or sulfur compound-containing addition material into the gas phase and for the reaction of gaseous mercury and gaseous additive material to mercury sulfide, and to a continuous feed reactor of the reactor ( 2 ) with the mercury and the addition material. Device according to claim 14, characterized in that that a preferably upright tubular reactor for the reaction is provided. Apparatus according to claim 14 or 15, characterized in that a quench ( 4 ) and / or a water jet pump is provided for cooling the mercury sulfide after the discharge from the reactor ( 2 ). Device according to one of the preceding claims, characterized in that between the reactor ( 2 ) and the quench ( 4 ) and / or the water jet pump, a heatable line ( 5 ) is provided for the mercury sulfide. Device according to one of the preceding claims, characterized in that a sedimentation basin and / or a centrifuge ( 6 ) to Solid-liquid separation is provided. Device according to one of the preceding claims, characterized in that a pressing device, preferably a filter press ( 7 ), is provided for pressing the mercury sulfide after solid-liquid separation. Device according to one of the preceding claims, characterized in that a drying device, preferably a vacuum mixer and / or a drying oven for drying the Mercury sulfides is provided after pressing.