DE102008006246B4 - Process and apparatus for the continuous production of mercury sulphide for subsequent disposal - Google Patents

Abstract

A process for the continuous production of mercury sulphide for subsequent disposal, the mercury sulphide resulting during a reaction in a reactor (2) 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 addition material, wherein the mercury and the addition material in the reactor (2) are heated and converted into a gaseous state and wherein the reaction between the mercury and the addition material takes place in the gas phase.

Description

The Invention enters a method and apparatus for continuous Production of mercury sulfide for subsequent disposal, wherein the mercury sulfide during a reaction process in a reactor from a reaction of elemental mercury and elemental sulfur and / or a sulfur compound-containing 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 is a danger to Represents human and the environment. Numerous accidents and almost irreversible environmental damage In the past, mercury has given rise to dubious popularity.

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 until towards cessation of primary mercury production at the known production sites. Nice For many years, recycled mercury is used in recycling plants from waste recovered and as an alternative to primary mercury offered on the market. Very large quantities Secondary mercury will be in the future with the worldwide conversion of existing chlorine production from Amalgam method for membrane method exempted. Becomes permanent 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 option to disposal to deliver.

A possibility the conversion of elemental mercury into a stabilized Mercury compound consists in the production of mercury sulfide (cinnabar). Mercury sulphide is a stable or stabilized compound, due to their known properties (non-toxic, chemically stable, and also under aggressive conditions) a lasting and safe storage of mercury. Incidentally, it is basically the same possible, Produce mercury sulfide using sulfur compounds.

From the US 5,034,054 A 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.

Out the reference "Römpps Lexikon Chemie, 10th edition, Georg Thieme Verlag, keyword "tubes, reactors" is a heated tubular reactor known, upstream and downstream of the plant parts could be, in which essentially according to physical principles to the Reaction prepared starting materials and formed Products are worked up.

task The present invention is now a method and an apparatus of the type mentioned above to provide with the mercury sulfide in a simple and cost-effective manner and as possible can be produced 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 the addition material in the Heated reactor and in a gaseous Condition are transferred and wherein the reaction between the mercury and the addition material takes place in the gas phase.

The invention relates to a continuous process for the immobilization of mercury by reaction with sulfur to mercury sulfide, wherein mercury and sulfur 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 5,034,054 A known methods for cost savings and procedural simplification. In this case, the inventive method is preferably designed such that the produced mercury sulfide meets the requirements for subsequent disposal, preferably for disposal underground.

In connection with the invention it has been recognized that the highly superstoichiometric addition of the addition material according to the US 5,034,054 A 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 to solution the task mentioned above, preferably indirectly heated Reactor for the transfer of elemental mercury and elemental sulfur and / or a sulfur compound containing addition material provided in the gaseous state, the reactor being over a correspondingly formed loading device continuously can be charged with the mercury and the addition material. The reactor may be a preferably upright tubular reactor act, which ensures high conversion rates of gaseous components. Moreover, the leads indirect heating of the reactor to simplify the process.

in the Related to the continuous production of mercury sulphide is further provided that the in the reaction in the reactor available mercury sulfide continuously vaporous discharged from the reactor becomes. The operating temperature in the reactor is preferably above the boiling point of mercury sulfide or above the evaporation temperature, so that the mercury sulfide formed not condensed or resublimed within the reactor. The Operating temperature in the reactor should therefore preferably above from about 580 °, but it can be higher chosen be to condensation or resublimation of mercury sulfide sure to exclude can. If the reactor is operated at negative pressure, the operating temperature be reduced accordingly.

Of the Operation of the reactor at temperatures in the range above the In addition, the boiling point of mercury sulphide leads to the starting materials be transferred after the entry into the reactor very quickly in the gaseous phase. Thereby let yourself 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 to be charged. This allows a procedurally simple continuous feed of the reactor with the starting materials. It understands that one Feeding device must be provided for continuous feeding of the reactor is formed with the homogenized mixture. Basically Also be provided a dosing, with mercury and addition material to the Reactor from storage tanks separated in the desired mixing ratio supplied become.

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 mass flows should be chosen that the calculated residence time of mercury and addition material in the reactor at least one second to six seconds, preferably less than four seconds, is. As a result, sufficient sales in the gas phase reaction between the mercury and the added material.

Preferably, the reactor and also the other involved in the production of mercury sulfide devices in the apparatus according to the invention is operated gas-tight, so that it in the continuous production of mercury sulfide does not lead to the escape of mercury sulfide in the Environment can come. As a result, an environmentally friendly generation of mercury sulfide from the starting materials is possible.

Of the Reactor can over a vacuum pump or a vacuum fan with a low vacuum be applied to the operational safety and to exclude the leakage of mercury sulfide from the reactor. It understands that the Operation under low vacuum all devices of the device according to the invention concerns that of gaseous Flows through mercury sulfide become.

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, which at an ambient pressure of 1 bar absolute pressures of 0.95 bar corresponds. The implementation 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 achieved which results in a high conversion rate with lower energy consumption guaranteed becomes.

Further is in the inventive method provided that the vaporous Mercury sulphide after removal from the reactor with a liquid or vaporous Coolant abruptly at least until reaching a fixed state, preferably to a temperature of less than 50 ° C, cooled and together with the cooling medium subjected to a solid-liquid separation becomes. At the cooling medium it may be water, wherein the cooling of the mercury sulfide a quench and / or a water jet pump is provided. In order to it does not lead to an unwanted condensation or resublimation of mercury sulfide comes before the sudden cooling, is a heated pipe for the mercury sulfide between the reactor and the quench and / or be provided the water jet pump. With operation of the quench or the water jet pump is in normal operation, a sufficient pressure gradient Reactor, so that the Possibility exists the system without vacuum pump or vacuum fan at low vacuum to operate without one Escape of mercury sulfide in the environment to be feared got to.

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

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 becomes explicit noted that all Range specified above and in the claims all, within Interval intervals and individual values in the relevant area 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 sulphide for subsequent disposal. Based the drawing below is the method of the invention described. However, it should be noted that the invention is not to the illustrated embodiment limited 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 above the boiling or Verdamp mercury sulphide, which is continuously fed to the reactor 2 supplied starting mixture of mercury and elemental sulfur in the gaseous state. This is followed by a continuously proceeding gas phase reaction between the starting materials present in the gaseous state, wherein the vaporous mercury sulphide obtainable in this way, with a calculated residence 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

Claims (19)

A process for the continuous production of mercury sulphide for subsequent disposal, wherein the mercury sulphide during a reaction process 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 feed additive 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 characterized in that cooled Mercury sulphide by solid-liquid separation of the cooling medium is separated. Method according to one of the preceding claims, characterized characterized in that cooling medium circulated becomes. Method according to one of the preceding claims, characterized 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 characterized in that the mercury sulphide after the solid-liquid separation pressed and optionally dried. Contraption ( 1 ) for the continuous production of mercury sulphide for subsequent disposal for carrying out the method according to one of the preceding claims, with a heatable reactor ( 2 ) for the conversion of elemental sulfur and an elemental sulfur and / or sulfur compound-containing addition material into the gas phase and for the reaction of gaseous mercury and gaseous addition material to mercury sulfide, and with a feed device for a continuous feed of the reactor ( 2 ) with the mercury and the addition material, a quench ( 4 ) and / or a water jet pump for cooling the mercury sulphide after removal from the reactor ( 2 ) and 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 claim 14, characterized in that the existence preferably upright tubular reactor is provided for the reaction. Apparatus according to claim 14 or 15, characterized in that a sedimentation basin and / or a centrifuge ( 6 ) is provided for solid-liquid separation. Apparatus according to claim 14 to 16, characterized in that a pressing device, preferably a filter press ( 7 ), is provided for pressing the mercury sulfide after solid-liquid separation. Apparatus according to claim 14 to 17, characterized that one Drying device, preferably a vacuum mixer and / or a drying oven, provided for drying the mercury sulfide after pressing is. Device according to one of claims 14 to 18, characterized in that the reactor ( 2 ) is indirectly heated.