HK1210088B - Mercury sorbent material comprising a sheared, ion-exchanged clay material - Google Patents

Description

Mercury adsorbent materials comprising sheared, ion-exchanged clay materials

The patent application of the invention is a divisional application of an invention patent application with the international application number of PCT// US2010/037580, the international application date of 2010, 6 months and 7 days, the application number of 201080026175.X entering the Chinese national stage and the invention name of a high shear method for preparing synthetic montmorillonite minerals.

Cross Reference to Related Applications

This application claims priority to U.S. application 12/485,561 filed on 16.6.2009, the entire contents of which are incorporated herein by reference.

Technical Field

The present invention relates to compositions, methods of making compositions, and methods of using compositions to remove mercury (organomercury, Hg) from gas streams (e.g., natural gas), industrial chimneys, and the like⁺(ii) a And/or Hg⁺²) The method of (1). The composition, "mercury removal medium," is particularly useful for removing mercury from flue gas emitted from coal-fired power plants. The Hg removal media comprises a homogeneous, preferably sheared, composition comprising a layered phyllosilicate, sulfur, and copper, forming a copper/sulfur/clay material. Copper ion-exchanges with clay cations and sulfur reacts with ion-exchanged and free copper to form a copper sulfide phase that binds the phyllosilicate through the combined action of various mechanisms.

Background and Prior Art

The emission of mercury from coal-fired and oil-fired power plants has become a significant environmental problem. Mercury (Hg) is a potent neurotoxin that can have an impact on human health at very low concentrations. The largest source of mercury emissions in the united states is the coal-fired power plant. These coal-fired power plants occupy one-third to one-half of the total mercury emissions in the united states.

The emission of mercury is mainly caused by flue gas (exhaust gas) emitted from burning coal. Hg is predominantly present in flue gas in three basic forms: elemental Hg, oxidized Hg, and particle bound mercury.

Currently, the most common method of reducing mercury emissions from coal and oil fired power plants is by injecting granular activated carbon into the flue gas. The activated carbon provides a high surface area material for mercury adsorption and particle-bound mercury accumulation. A disadvantage of adding activated carbon to the flue gas is that the activated carbon will remain in the fly ash exhaust gas. Fly ash extracted from coal-fired power plants is often added to concrete where the presence of activated carbon adversely affects performance.

Another method of reducing Hg emissions is to add chemicals that react with mercury to chemisorb elemental Hg and oxidize Hg. One class of materials capable of chemically reacting with Hg is metal sulfides. U.S. Pat. Nos. 6,719,828 and 7,048,781 teach the preparation of layered adsorbents such as clays with metal sulfides between the clay layers. The process for preparing the layered adsorbent is based on an ion exchange process which limits the selection of substrates to those with high ion exchange capacity. Furthermore, the disclosed ion exchange is time consuming and includes several wet steps that severely compromise regeneration capacity, performance, scalability, equipment requirements, and sorbent cost. The process for making the adsorbent, according to the teachings of U.S. patent No.6,719,828, involves swelling a clay in an acidified solution, adding a metal salt solution to exchange metal ions in the clay layers, filtering the ion-exchanged clay, redispersing the clay in solution, adding a sulfide solution to sulfide the clay, and finally filtering and drying the material. Another disadvantage of the process disclosed in U.S. patent No.6,719,828 is the environmental liability of the by-products of the ion exchange reaction, that is, the waste solution of metal ions and the hydrogen sulfide produced.

Published U.S. patent application No.11/291,091 teaches a process for preparing a metal sulfide/bentonite composite for removing mercury from a flue gas stream. Two methods, an incipient wetness method and a solid state reactive milling method, are taught in this application for preparing composites. These processes are similar in that a copper salt is mixed with the bentonite clay, followed by the addition of a sulfide salt. These processes differ in the method of adding the sulfide salt. In the first method, the sulfide salt is added via an "incipient wetness" procedure, in which the sulfide salt is dissolved in water and added to the copper/clay mixture as an aqueous solution; in the second method, the sulfide salt is added by a "solid state reactive milling" process in which the hydrated sulfide salt is milled with the aqueous copper/clay mixture. This application further teaches that the incipient wetness and solid-state milling methods differ from the "wet method" of U.S. Pat. No.6,719,828 because there is no ion exchange reaction between the copper ions and the cations of the bentonite clay. The composite properties of the materials produced in this application are confirmed by the particle X-ray diffraction pattern, which provides evidence of the formation of copper blue (CuS), which is consistent with the copper sulfide produced in U.S. patent No.6,719,828.

Although U.S. application No.11/291,091 claims no ion exchange reaction, copper salts and bentonite clays readily form very stable copper/clay compositions by ion exchange. See butyl, Z. (Ding, Z.) and r.l. perostol (r.l. frost) "thermal study of copper adsorption on montmorillonite" (thermomethiica Acta, 2004,416, 11-16). Analysis of these compositions confirmed interlayer ion exchange (intercalation) and marginal adsorption of copper salts. A review of "kinetic and thermodynamic studies of copper ion exchange on Na-montmorillonite clay minerals" by El-Tartarian (El-Batauti) et al (J.colloid and Interface Sci.2003,259, 223-227).

However, there remains a need to provide improved pollution control adsorbents and methods for their manufacture. It would be desirable to provide an adsorbent comprising a metal sulphide on a substrate that can be manufactured easily and at low cost. In this regard, there is a need for a simple and environmentally friendly process that can efficiently convert readily available substrates to chemisorbents without the need to include extensive steps in the ion exchange process.

SUMMARY

The mercury sorbent material is made by the following steps: preparing a copper/clay mixture by mixing a dry clay having less than about 15% by weight water and a dry copper source having a water content consisting essentially only of molecular water of hydration; a sulfur/clay composition is prepared by mixing a dry clay having less than about 15 weight percent water and a dry sulfur source having a water content consisting essentially only of hydrated molecular waterMixing; mixing the copper/clay mixture and the sulfur/clay mixture to obtain a pre-mixture of the mercury sorbent, and shearing the pre-mixture of the mercury sorbent to form the mercury sorbent material, wherein the mercury sorbent material has less than about 4 wt% water when the mercury sorbent material contains less than about 4 wt% waterWherein the powder X-ray diffraction pattern of the mercury sorbent material is substantially absent fromAnd wherein the zeta potential of the mercury sorbent material is greater than the zeta potential of the dry clay. In a preferred embodiment, the shearing is effected by passing the mercury sorbent material through an extruder at a moisture level of about 15 to 40 weight percent, more preferably about 20 to 30 weight percent.

Brief Description of Drawings

Figure 1 is a process diagram for preparing a mercury sorbent material by shear mixing;

FIG. 2 is a view of a montmorillonite structure showing the d (001) spacing which can be measured by powder X-ray diffraction;

FIG. 3 is a powder X-ray diffraction complex diagram of sodium montmorillonite. The lines represent the low angle diffraction pattern of sodium montmorillonite, which contains from about 0.9 wt% to about 24.4 wt% water;

fig. 4 is a powder X-ray diffraction composite of the mercury sorbent materials described herein. The lines represent the low angle diffraction pattern of a material containing from about 0.6 to 22 wt% water; and is

FIG. 5 is a powder X-ray diffraction complex plot of approximately 30 to 352. theta. for the following samples: sodium montmorillonite, sodium montmorillonite containing about 4.5 wt.% copper blue, and a mercury sorbent material described herein containing an equivalent amount of 4.5 wt.% copper sulfide.

Detailed description of the invention

The mercury sorbent material described herein is a layered clay material comprising copper and sulfur, made by shearing sorbent components, specifically clay, a copper source and a sulfur source. The process disclosed herein is accomplished by ion exchanging the clay cations with the cations of the copper component of the adsorbent, and perturbing the standard reaction scheme. Analysis of the mercury sorbent materials described herein shows that the materials do not contain the kinetic reaction products described in the prior art.

In accordance with one aspect of the methods and materials disclosed herein, the mercury sorbent material comprises a silicate clay material. The silicate clay (phyllosilicate) may be a smectite clay, for example, bentonite, montmorillonite, hectorite, beidellite, saponite, nontronite, volkonskoite, sauconite, stevensite (stevensite), and/or a synthetic smectite derivative, in particular, fluorohectorite and laponite; a mixed layered clay, in particular rectorite (rectonite) and their synthetic derivatives; vermiculite, illite, micaceous minerals, and synthetic derivatives thereof; layered hydrated crystalline polysilicates, in particular, sodalite, kenyaite, octasilicate (ocissiate), magadiite and/or kenyaite; attapulgite, palygorskite, sepiolite; or any combination thereof. The clay material should have exchangeable cations. Preferably, the silicate clay material is a montmorillonite having exchangeable calcium and/or sodium ions.

Another important aspect of the methods and materials disclosed herein is a reactive copper compound. As used herein, a reactive copper compound is a copper-containing material that reacts with sulfur and/or sulfide ions. The reactive copper compound provides a source of copper for the methods and materials disclosed herein. Preferably the copper source is a dry material. In this context, a dry copper source is defined as a reactive copper compound, in powdered, layered or crystalline form, containing no more water than the complex water contained in the crystal structure of the solid copper compound. Copper compounds that provide the copper source include, but are not limited to, anhydrous and aqueous forms of: copper acetate, copper acetylacetonate, copper bromide, copper carbonate, copper chloride, copper chromate, copper ethylhexoate, copper formate, copper gluconate, copper hydroxide, copper iodide, copper molybdate, copper nitrate, copper oxide, copper perchlorate, copper pyrophosphate, copper selenide, copper sulfate, copper telluride, copper tetrafluoroborate, copper thiocyanate, copper trifluoromethanesulfonate, metallic copper, copper alloys, and mixtures thereof. Preferably, the copper source is a cu (ii) salt having a copper cation and a copper salt anion, more preferably, the copper source is a cu (ii) salt wherein the copper salt anion is more enthalpically paired with a sodium cation than with a copper cation, more preferably, the copper source is a cu (ii) salt wherein the copper salt anion is more enthalpically paired with a calcium cation than with a copper cation, more preferably, the copper source is copper sulfate.

Yet another important aspect of the methods and materials disclosed herein is a reactive sulfur compound. As used herein, a reactive sulfur compound is a copper-containing material that reacts with copper and/or copper ions and provides a sulfur atom or polysulfide. The reactive sulfur compound provides a source of sulfur for the methods and materials disclosed herein. Preferably the sulphur source is a dry material. In this context, a dry sulfur source is defined as a reactive sulfur compound in the form of a powder, flakes, crystals or gas containing no more water than the complex water contained in the crystal structure of the solid sulfur source. Sulfur compounds that provide a source of sulfur include, but are not limited to: sodium sulfide, sodium disulfide, sodium polysulfide, ammonium sulfide, ammonium disulfide, ammonium polysulfide, potassium sulfide, potassium disulfide, potassium polysulfide, calcium polysulfide, and mixtures thereof, in anhydrous and aqueous forms. Sulfur compounds that provide a source of sulfur include, but are not limited to: sulfur in anhydrous form, hydrogen sulfide, hydrogen disulfide, aluminum sulfide, magnesium sulfide, thiolacetic acid, thiobenzoic acid, and mixtures thereof. Preferably the sulphur source is a sulphide or polysulphide salt, more preferably a sulphideThe source is a sulfide salt, more preferably the sulfide source is a sodium sulfide, more preferably the sulfide source is selected from Na₂S，Na₂S·3H₂O and Na₂S·9H₂In O, more preferably the sulfide source is Na₂S·3H₂O。

It is also an important aspect of the methods and materials disclosed herein that no copper + sulfur chemical reaction occurs prior to the application of shear to the reactive compounds. One measure to prevent the chemical reaction of copper + sulfur prior to the application of shear to the reactive compound is to dilute the copper source with the sulfur source with a clay material. It is sufficient for the person skilled in the art to recognize that the reaction rate depends on the concentration and that the reactions of the copper source and the sulfide source also have a similar dependence. Moreover, the reaction of the copper source with the sulfide source is inhibited by the absence of free water. The addition of water, and possibly the formation of a copper solution, and/or the formation of a sulfide solution, will greatly increase the rate of reaction of the copper source with the sulfide source. In this context, any solid state reaction will depend on the movement of the ions and the exposed surface area of the copper and sulfur sources, and therefore the rate of such solid state reaction will be very low.

Preferably, the copper source is mixed with the clay material prior to introducing the copper/clay mixture into the mechanical shearing device, as shown below. Similarly, it is preferred that the sulfur source is mixed with the clay material prior to introducing the sulfur/clay mixture into the mechanical shearing device. Alternatively, the copper/clay mixture and the sulfur/clay mixture may be mixed to form a mercury sorbent pre-mixture prior to adding the mercury sorbent pre-mixture to the mechanical shearing device. Yet another method of feeding the material to the mechanical shearing device is to mix the clay material with a copper source and a sulfur source (optionally adding the copper source to the clay material first, adding the sulfur source to the mercury sorbent pre-mixture, or any variation in the order of them). Those skilled in the art will appreciate that the order of addition will vary depending on the particular (reactive compound) source. Alternatively, the copper/clay and sulfur/clay mixtures may be added separately to the mechanical shearing device. The addition of the single or multiple dry materials to the mechanical shearing device may be carried out by any means available to those skilled in the art.

In one embodiment, the copper/clay mixture and the sulfur/clay mixture are prepared and mixed in a single process in which the copper source and the sulfur source are added to the clay material. The mixture is then agitated with a non-shear mixer to disperse the copper source and the sulfur source throughout the clay material to form a mercury sorbent pre-mixture. An example of a non-shearing mixer is a paddle type mixer.

The amount of copper source added to the amount of sulfide source added is adjusted to provide a preferred molar ratio of copper ions to sulfide ions, which can be understood as the manner of measurement of copper atoms and sulfur atoms. For example, when the sulfide source is a polysulfide, the copper ion to sulfide ion ratio represents the molar ratio of copper atoms (ions) to sulfur atoms, the latter having S_x ^2-Formula (I) wherein X is greater than 1. The ratio of copper ions to sulfide ions is between about 0.1 and about 10. Preferred ratios (Cu: S) are about 0.1,0.2, 0.3, 0.4, 0.5, 0.7, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.0. When the sulfide source is a polysulfide, the ratio is generally less than 1. In a preferred embodiment, the copper ion to sulfur ion ratio is less than about 1, more preferably less than about 0.5; in another preferred embodiment, the ratio is greater than about 1, more preferably greater than about 2.

The copper source is added to the clay material in a weight ratio approximately equivalent to the cation exchange capacity of the clay. Cation exchange capacity is a measure of the molar equivalents of exchangeable clay cations, and weight ratio is a measure of the molar equivalents of copper cations added to the clay. The copper source of the clay material is preferably added such that about 10 to 300 millimoles (mmol) of copper are added to about 100g of clay, more preferably about 20 to 200mmol of Cu are added to about 100g of clay, and still more preferably about 50 to 150mmol of Cu are added to about 100g of clay.

Yet another important aspect of the methods and materials disclosed herein is the shear of the mercury sorbent pre-mixture. Machine with a movable working partThe shearing method may be performed using an extruder, an injection molding machine,a model-type mixing machine, which is composed of a mixing chamber,type mixers, pin mixers (pin mixers), and the like. Shearing can also be achieved by introducing the copper/clay mixture and the sulfur/clay mixture into one end of an extruder (single or twin screw) to obtain a sheared material at the other end of the extruder. The temperature at which the material enters the extruder, the temperature of the extruder, the concentration of the material added to the extruder, the amount of water added to the extruder, the length of the extruder, the residence time of the material in the extruder, the extruder design (single screw, twin screw, number of flights per unit length (flight), depth of grooves, cleanliness of flights, mixing zone, etc.) are several variables that control the amount of shear applied to the material.

Preferably, water is added to the mechanical shearing unit to facilitate shearing of the mercury adsorbing pre-mixture and reaction of copper with clay (ion exchange), and reaction of copper with sulfur. Since most mechanical shearing units are of variable design, such as feed capacity, the amount of water added to the unit is preferably defined by the weight percentage of water in the sheared material. Preferably, the mercury sorbent material, after exiting the mechanical shearing unit, comprises from about 15 to about 40 weight percent water, more preferably from about 20 to about 30 weight percent water, more preferably from about 23 to about 28 weight percent water.

One method for determining the structure and composition of the materials disclosed herein is powder X-ray diffraction (powder XRD). The powder XRD pattern of the clay material is characterized by a broad, low-angle peak corresponding to the silicate interlayer spacing, see fig. 2. Often used to determine the water content of water-swellable clays, the maximum peak of this low-angle peak corresponds to an angle that decreases with increasing interlayer spacing, see fig. 3, where the maximum peak decreases with increasing amount of water adsorbed within the interlayer. For example, in a sodium montmorillonite clay, the diffraction angle occurs at about 7 ° 2 ΘCorresponds to aboutThe d (001) interlamellar spacing, occurring at an angle of about 9 ° 2 Θ, corresponds to aboutThe d (001) interlamellar spacing of (a), is close to the thickness of the clay platelets. The change in d (001) interlayer spacing of montmorillonite Clay and Clay samples after addition of copper ions was observed in "copper (II) ethylenediamine orientation and interaction with montmorillonite" by Burba and McAtee (Clay and Clay Minerals,1977,25113- & 118) were subjected to detailed study. That article reports intercalation and multi-lamellar bonding of copper ions, and that the average d (001) interlayer spacing for copper (II) montmorillonite samples is about. The d (001) interlayer spacing of the layered copper-sulfide// silicate// copper-sulfide materials disclosed in U.S. Pat. No.6,719,828 would be significantly greater than the thickness of the added copper-sulfide layer. The surface deposited copper sulfide material disclosed in U.S. patent application No.11/291,091 exhibits the same d (001) interlamellar spacing as the original montmorillonite (see fig. 3), because, as taught, the copper-sulfide in that patent only deposits on the clay surface. Herein, when the water content of the material is less than 4% by weight, the methods and materials used are found to have a water content of less than aboutD (001) layer spacing of (2). For example, FIG. 4 shows that the materials and methods disclosed herein are inconsistent with the reported structure in the prior art.

Also, the mercury sorbent materials disclosed herein are substantially free of copper blue, a copper sulfide mineral disclosed in U.S. patent application No.11/291,091. The copper blue is copper (II) ion and sulfide (S)^2-) Kinetic reaction products of ionsThe molecular formula is CuS. The powder XRD diffractogram of ceruloplasmin includes at least four characteristic reflections; three of these reflections cover the reflections of the montmorillonite clay material. In thatThe reflection (where the change in position of the reflection occurs depends in part on the accuracy of the diffractometer) is characteristic of the ceruloblue material and can be observed in samples where clay is the major constituent. Figure 5 shows the diffractograms for three powder XRD patterns between the 30 ° to 35 ° 2 · Θ region. The XRD diffractogram of the copper free sulfide clay is shown at the bottom; the XRD diffractogram of the clay containing 4.5 wt% of copper blue is shown in the middle; the XRD diffractogram of the clay material containing an equivalent amount of 4.5 wt% copper sulfide disclosed herein is shown at the top. In thatThe copper blue reflections at (a) are marked by vertical dashes. As clearly shown by the powder XRD patterns, the materials disclosed herein are essentiallyNo diffraction peak appears.

Yet another important aspect of the methods and materials disclosed herein is that the zeta potential value of the mercury sorbent material is higher (less negative) than the zeta potential value of the clay material used to prepare the mercury sorbent material. The surface charge on a microparticle (e.g., clay) can generally be determined by measuring zeta potential and/or electrophoretic mobility. The clay structure applicable herein is partly composed of a silicon-oxygen (silicate) arrangement (such an arrangement is known from Bragg et alCrystal Structures of Minerals (crystal structure of mineral)Page 166-382 (Cornell University Press 1965) and incorporated herein for the structure and chemical formula of the silicate material. The silicate portion of the clay typically has an anionic charge, which is balanced by alkali and/or alkaline earth cations in the material. Suspensions of these materials and their zeta potential measurements provide an evaluation of ions in clay materialsPairing (cation to silicate) method. The lower (more negative) the zeta potential, the greater the percentage of weak ionic interactions between the cation and the silicate. A higher (less negative) zeta potential indicates a stronger ionic or covalent interaction between the cation and the silicate. It is expected that mixing a neutral material with a clay material will not change the zeta potential of the clay material. Ion exchange of alkali and/or alkaline earth cations of the clay material is expected to change the zeta potential if the exchanged ions have different binding energies to the silicate.

Yet another important aspect of the methods and materials disclosed herein is that the material particle diameter can be captured by the particle collector of a coal fired electric power plant. Preferably, the average particle diameter is greater than 0.1 μm, more preferably greater than 1 μm. The preferred average particle diameter of the mercury sorbent materials disclosed herein for mercury sorption in flue gas depends on the particle collector in the industrial power plant. Examples of particle collectors include bag house fabric filters, electrostatic precipitators and cyclone collectors. It is well known in the art that large particles are easier to separate from flue gas. Preferably, the majority of the particles have a diameter in the range of about 1 to about 100 μm, more preferably about 1 to about 50 μm, and most preferably about 10 to about 25 microns.

Unexpectedly, the materials disclosed herein are not reduced in size by the shearing process, as described above. Shear, particularly high shear mixing, is known to cause a reduction in the particle size of the clay material due to the dissociation of the silicate layers. In this context, sheared materials were found to have particle diameters larger than those of the dry (less than about 15 wt% water content) clay starting material. Furthermore, the particle diameter distribution was found to vary based on the mechanical shearing method. The samples sheared with the pin mixer were found to have a majority of average diameter of about 3.8 μm and a minority of average particle diameter of about 20 μm. The samples sheared with the extruder were found to have the same average particle diameter with an additional small fraction of particles averaging about 40 μm in diameter. Without being bound by any particular theory, it is assumed that the growth of 20 μm and 40 μm particle size materials is characteristic of clay material dissociation, growth of copper sulfur material on the step edge, and accumulation of exposed clay surfaces on or near the charged copper sulfur phase.

Yet another important aspect of the methods and materials disclosed herein is the irreversible combination of mercury and the mercury sorbent material in the flue gas stream. In this context, irreversible binding means that the chelated mercury sorbent material cannot be leached by water or a solvent that is primarily water.

The mercury sorbent material may remain in the fly ash exhaust stream. While fly ash containing activated carbon is detrimental to the formation and stability of concrete, fly ash containing mercury sorbent material preferably does not impair the formation and/or stability of concrete. Preferably, the mercury sorbent material does not increase the amount of Air Entraining Agent (AEA) necessary to form the concrete, one of the ways to measure it is the foam index test value. More preferably, the mercury sorbent material does not absorb or react with the AEA, and more preferably the mercury sorbent material assists the AEA in forming stable 10 to 250 μm cavities in the formed concrete. Also, preferably, the absorbed (sequestered) mercury does not leach from the mercury sorbent material during or after formation of the concrete. In addition, the contained mercury sorbent material preferably prevents degradation of the concrete. Methods of preventing concrete degradation include limiting and/or preventing alkali silicate reaction, carbonation, sulfate attack, leaching, and/or structural damage during freeze/thaw cycles. Without being bound by any particular theory, the materials described herein preferably prevent degradation of the concrete by moisture adsorption and limited expansion to improve freeze/thaw cycling of the concrete, and/or prevent degradation of the concrete by preventing ion leaching. An additional benefit of the materials described herein is the similarity in block structure to cement, silicate-aluminum materials, preferably supporting chemical bonding of the mercury sorbent material to the prepared concrete.

The mercury sorbent can be tested and evaluated for its performance under different conditions:

one laboratory bench scale experiment used nitrogen, air and simulated flue gas, and typically the adsorbent was placed on a fixed bed. Simulating the flue gas being at high temperature and having SO as a component₂，NO_x，HCl，CO₂，O₂，H₂O and Hg⁰. The gas stream passes through the adsorbent bed at a certain flow rate. The exhaust gas was analyzed for mercury concentration with a mercury analyzer. The experiment can be run for a sufficient time to reach adsorption equilibrium. Both mercury removal efficacy and absorption capacity can be concluded at the end of the experiment. Factors that affect the results are temperature, mercury oxidation state, and flue gas composition. Small scale experiments are a very economical method for screening adsorbents.

A pilot scale experiment was very effective for studying adsorbent performance at conditions close to real industrial conditions. The test unit is typically installed for flight experiments. Simulated flue gas, or a slipstream flue gas, may be extracted from an industrial facility, such as a power plant ESP (electrostatic precipitator) or a fabric filter unit, may be used to store the sorbent. The sorbent was injected into the experimental system and the mercury concentration was monitored to detect changes in mercury concentration. The contact time of the sorbent and the flue gas only needs a few seconds.

Finally, a full scale power plant experiment may be arranged. The design and selection of the injection system, and the rapid and accurate measurement of mercury concentration, are important factors during the evaluation.

Examples

The following examples are given to illustrate the present invention, but are not intended to limit the scope of the present invention.

Example 1

In a bowl of an KITCHENAID vertical mixer, 368.5g of sodium bentonite (85% passing through a 325 mesh screen), 16.5g of sodium chloride, (sourced from United Salt Corporation, passing through a 20 mesh screen), 57.0 g copper sulfate pentahydrate (Old Bridge Chemicals, Inc., passing through a 40 mesh screen), and 31.0g sodium sulfide trihydrate (Chem One Ltd. (chemical first Co., Ltd)) were mixed for 5 minutes. 74.0g of deionized water was then added to the mixture and stirred for 5 minutes. The mercury sorbent mixture was then extruded three times with a laboratory scale extruder having a die. The extrudates were dried in an oven at 100 ℃. The dried extrudate was milled and the resulting particles were passed through a 325 mesh screen and collected. The final water content of this sample was about 2 wt%.

Example 2

In a bowl of an KITCHENAID vertical mixer, 232.0g of sodium bentonite, 26.4g of sodium chloride, 91.2g of copper sulfate pentahydrate, and 49.6g of sodium sulfide trihydrate were mixed for 5 minutes. Then, 52.4g of deionized water was added to the mixture and stirred for 5 minutes. The mercury sorbent mixture was then extruded three times with a laboratory scale extruder having a die. The extrudates were dried in an oven at 70 ℃. The dried extrudate was milled and the resulting particles were passed through a 325 mesh screen and collected. The final water content of this sample was about 3.5 wt%.

Example 3

2,060 pounds of sodium bentonite, 92.2 pounds of sodium chloride, 318.6 pounds of copper sulfate pentahydrate, 173.3 pounds of sodium sulfide trihydrate were mixed in the bowl of a paddle mixer to prepare a mercury adsorbing mixture. After the mixture was mixed for 20 minutes, it was fed to a 5-inch READCO continuous processor (manufactured by READCO Manufacturing Inc., reed co, Inc.) at a feed rate of about 900 lbs/hr. When the mercury sorbent mixture was fed to the processing machine, water was fed to the processing machine through a liquid injection port (separate from the dry mixture feed port) at a rate of about 0.35 gallons per minute. The extrudate is dried at about 100 c and milled to reduce particle size. The mercury sorbent material was found to have an average particle size of about 5 to about 25 μm and a water content of less than 10 wt.%.

Example 4

700 pounds of sodium bentonite, 31.3 pounds of sodium chloride, 108.3 pounds of copper sulfate pentahydrate, and 59.0 pounds of sodium sulfide trihydrate were mixed in the bowl of a paddle mixer to prepare a mercury adsorbing mixture. After mixing the mixture for 20 minutes, it was fed to a 16 "pin mixer (Mars Mineral) at a feed rate of about 1,100 lbs/hr. When the mercury sorbent mixture was fed to the pin mixer, water was fed to the processing machine through a liquid injection port (separate from the dry mixture feed port) at a rate of about 0.35 gallons per minute. The extrudate is dried at about 100 c and milled to reduce particle size. The mercury sorbent material was found to have an average particle size of about 5 to about 25 μm and a water content of less than 10 wt.%.

The foregoing description is for clarity of understanding only and no unnecessary limitations are to be understood therefrom, as modifications within the scope of the invention will be apparent to those skilled in the art.

Claims (10)

1. A mercury sorbent material comprising a sheared, ion-exchanged clay material comprising clay, copper and sulfur but being substantially free of clay/copper blue complexes as determined by powder X-ray diffraction and having a powder X-ray diffraction pattern in which substantially no sites are presentThe peak of (a) is present,

wherein the clay material is produced by shearing a mixture of clay, a copper source, a sulfide source, and water;

wherein the mercury sorbent material has a water content of less than 4 wt.% when the mercury sorbent material has a water content of less than 4 wt.%D (001) interlamellar spacing of (a);

wherein the zeta potential of the mercury sorbent material is greater than the zeta potential of the dry clay.

2. The mercury sorbent material of claim 1, wherein the copper source is selected from the group consisting of: copper acetate, copper acetylacetonate, copper bromide, copper carbonate, copper chloride, copper chromate, copper ethylhexoate, copper formate, copper gluconate, copper hydroxide, copper iodide, copper molybdate, copper nitrate, copper oxide, copper perchlorate, copper pyrophosphate, copper selenide, copper sulfate, copper telluride, copper tetrafluoroborate, copper thiocyanate, copper trifluoromethanesulfonate, copper, and mixtures thereof.

3. The mercury sorbent material of claim 1, wherein the copper source is a hydrated copper compound, the copper compound of the hydrated copper compound being selected from the group consisting of: copper acetate, copper acetylacetonate, copper bromide, copper carbonate, copper chloride, copper chromate, copper ethylhexoate, copper formate, copper gluconate, copper hydroxide, copper iodide, copper molybdate, copper nitrate, copper oxide, copper perchlorate, copper pyrophosphate, copper selenide, copper sulfate, copper telluride, copper tetrafluoroborate, copper thiocyanate, copper trifluoromethanesulfonate, and mixtures thereof.

4. The mercury sorbent material of claim 1, wherein the sulfide source is selected from the group consisting of: sodium sulfide, sodium sulfide trihydrate, sodium sulfide nonahydrate, sodium disulfide, sodium polysulfide, ammonium sulfide, ammonium disulfide, ammonium polysulfide, potassium sulfide, potassium disulfide, potassium polysulfide, calcium polysulfide, and mixtures thereof.

5. The mercury sorbent material of any one of claims 1-4, wherein the molar ratio of copper to sulfur is less than 1.

6. The mercury sorbent material of claim 5, wherein the molar ratio of copper to sulfur is less than 0.5.

7. The mercury sorbent material of any one of claims 1-4, wherein the molar ratio of copper to sulfur is greater than 1.

8. The mercury sorbent material of claim 7, wherein the molar ratio of copper to sulfur is greater than 2.

9. The mercury sorbent material of any one of claims 1-4, wherein the clay comprises a phyllosilicate selected from the group consisting of: bentonite, montmorillonite, hectorite, beidellite, saponite, nontronite, volkonskoite, sauconite, stevensite, hectorite, laponite, rectorite, vermiculite, illite, mica minerals, sodalite, kenyaite, octasilicate, magadiite, kenyaite, attapulgite, palygorskite, sepiolite, and mixtures thereof.

10. The mercury sorbent material of claim 9, wherein the clay comprises montmorillonite.