MXPA97001827A - Methods to decontaminate lands that continue metallic noci - Google Patents

Abstract

Land that includes sand and clays contaminated with nuclear waste materials and / or metal ions or harmful non-radioactive metalloids are decontaminated when treated with anhydrous liquid ammonia alone or in combination with solvated electrons. Methods include removing ions from harmful metals or metalloids when mixing with ammoniacal solutions to provide a product containing ammoniacal liquid with coordination complexes. Also methods comprise concomitant concentrates, such as plutonium and thorium, for example in earth and clay fines to give residual earth products that are sufficiently free of contaminants to allow recovery. The economy is improved over aqueous systems since ammonia can be recovered and recycled. By concentrating nuclear and non-nuclear waste in land fines, the space requirements that are ordinarily required for the storage of untreated land or land and the costs of managing it can be significantly reduced.

Description

METHODS TO DECONTAMINATE GROUNDS CONTAINING HARMFUL METALS TECHNICAL FIELD The present invention relates to methods for decontaminating land, and more particularly to the decontamination of land containing nuclear waste, land or land contaminated with non-radioactive harmful metal or metalloid ions and land contaminated with mixed waste, by methods that also allow the recycling of residual land products. BACKGROUND OF THE INVENTION As a result of military testing programs involving the detonation of nuclear devices, both in the United States of America and abroad, the environment, and particularly large areas of land in test areas, have been contaminated with materials. of nuclear waste. In some cases, for example, the detonation of a nuclear device failed to achieve the required critical mass of the radioactive components, resulting in substantial amounts of uranium and plutonium and enriched disperses over large areas of desert testing terrains. In addition to nuclear testing programs, soil contamination with radioactive materials has occurred at nuclear weapons sites, such as in Hanford, Washington; Roc and Fiats, Colorado; Savannah River, Georgia; Oak Ridge, Tennessee, and elsewhere through spills or landslides or releases to the environment. Efforts to successfully decontaminate these sites have proven to be difficult and extremely costly due to massive amounts of land that requires treatment and / or storage. Cleaning has usually meant a slow and expensive process, where the contaminated land is dug and transferred to a different site for storage. Abandoned salt mines and mountain deposits have been proposed as storage facilities for nuclear waste, but are often rejected later for technical and / or political reasons. Because a finite amount of space available to store nuclear waste materials advances in the recovery of contaminated sites has been slow. In an effort to mitigate the nuclear waste storage crisis, systems have been proposed to reduce voluminous amounts of contaminated land that requires storage, where the radioactive components are concentrated in a fraction of the land. A system, for example, employs an aqueous washing process that requires the use of chemical products for soil cleansing, multiple separation stages, water treatment and so on. Although it is quite effective in concentrating radioactive components in silt and clay fractions of the earth, capital and operating costs per ton of treated land are seen as economically unattractive. Consequently, most of the proposed methods for concentrating nuclear waste have not received wide acceptance. Like nuclear waste, the contamination of the environment by metal ions, especially when present in the ground or in groundwater, presents serious threats to human, animal and plant life. Metals such as lead, chromium, cadmium and arsenic have been released to the environment in quantities that make large-scale corrective projects necessary in order to protect the health of the general public. These metals represent some of the most difficult environmental pollutants to treat because they form salts or oxides, which in turn dissociate into oxidized species, which facilitates their introduction into the food and biological chains. Accordingly, there is a need for an effective innovative cost process to decontaminate land containing nuclear waste materials, such as those generated at nuclear weapons plant sites, nuclear testing sites, and where treatment requires substantial handling. volumes of land contaminated with radio active materials. The process should allow space reduction of another form required for storage of untreated land by concentrating on a small fraction of the land while also allowing the recycling of these sites. Equally, an effective cost process is required to decontaminate land containing metal ions and harmful nonradioactive metalloids, such as mercury, arsenic, selenium, chromium, lead, etc., and mixed wastes containing these noxious ions, along with nuclear waste as radionuclides of the actinide series, and / or organic compounds such as PCBs. SUMMARY OF THE INVENTION Therefore, a main objective of the invention is to provide improved economical methods for separating radioactive and non-radioactive components from contaminated soils, where the treated land is sufficiently free of the potentially toxic components, i.e. metals and metalloids, to allow land recycling. The phrase "sufficiently free" is intended to mean treated land in accordance with the present invention, such that (i) it is virtually devoid of all radioisotopes (radio nuclides) and desired, or (ii) contains residual amounts of radioisotope of low level allowing recycled soil to be recycled as is, or (iii) contains quantities of low level radioisotopes that can be diluted sufficiently with an inert material to reduce its activity to an acceptable level. Expressions, such as "nuclear waste" and "radioactive waste" as described in the specification and claims, are intended to also refer to soils contaminated with isotopic forms of elements that have unstable nuclei that disintegrate and emit energy more commonly as particles alpha, beta particles and gamma rays. They mainly include nuclear fission products or by-products or unreacted products from a nuclear device. Representative examples that include radio nuclides such as Cs137; Co60; K * °; Pu236; U235; U238; Ru103; Tea; Sr90; Rb; Y; Re; Rh; P.S; Tea; Np; and Am. Methods of the invention provide recovery of nuclear waste materials in ground fractions, particularly in small, high surface area particles, such as earth fines, and clay sludge fractions for subsequent storage or further treatment. By concentrating nuclear waste materials in soil fines, and silt of clay, for example, the storage space requirement per tonne of land is significantly reduced, probably as much as 90% compared to the otherwise required storage space requirements. for untreated land. The methods of the invention comprise the steps of: (a) mixing an ammonia liquid or liquid ammonia with a ground contaminated with nuclear waste in a closed vessel to form a dispersion or mud of the ground containing nuclear waste-ammonia; (b) allowing soil particles to be selectively precipitated from the sludge or dispersion of step (a) to form a lower phase of soil particles, while forming a higher liquid-solid phase comprising dispersed earth fines for soil in the ammoniacal liquid; (c) separating the upper solid-liquid phase from the lower solid phase of ground particles, the fines of the liquid-solid phase superior have the majority of the radionuclide contaminants, or in other words, the lower solid phase is sufficiently free of nuclear waste material for recycling of soil particles; and (d) separating the ammoniacal liquid from the earth fines containing the nuclear waste material for disposal or for further treatment of the fines. The term "waste" is intended to include a storage of earth fines containing nuclear waste. The expression "further treatment" is intended to include any process that will modify the potentially toxic properties of the radionuclide material to substances of reduced toxicity that impact the environment or the environment, or to materials that can be recovered as useful by-products. It will be understood, that methods of storage and additional treatment of the concentrated nuclear waste material do not constitute part of this invention. These methods are known to people with skill in the specialty. Mazur et al. In U.S. Pat. Do not. ,110,364 describe ammonia as a pre-treatment to desorb organic compounds, and particularly organic halogenated compounds such as PCBs from the soil, followed by chemical destruction of the compound by dehalogenation through a chemical reduction mechanism with solvated electrons. Mazur et al., However, fail to illustrate or suggest the use of ammonia as a means to separate ground into fractions where smaller, larger surface area particles are allowed to separate from the less dense liquid ammonia-containing phase. the earth fines of superior surface area, smaller. In contrast, the methods of Mazur et al. Allow "whole" soil to be treated in the reduction of halogenated carbon compound contaminants without isolating ground particles or ground fractions from the earth / ammonia sludge by allowing phase separation to occur and various stages of separation. By chance, it was found that the nuclide rays appear to have a preferential affinity for the finer surface, smaller surface areas and silts of clays and sands. Therefore, by isolating silt fines and particles, especially smaller particles that have higher surface areas relative to the particles that precipitate from earth-ammonia dispersions, it is in effect to selectively concentrate the nuclear waste material in the smaller volume of natural solid carrier material to effectively reduce the volume in tons of material that requires storage or further treatment. Accordingly, a primary objective of the invention is to provide an improved economical method for concentrating a substantial portion of the nuclear waste material in a reduced fraction of land for more efficient management of land clearing projects involving large volumes. of earth, to allow the recycling of substantial volumes of previously contaminated land. Still a further objective of the invention is to optionally include the stage of recovering and recycling for reuse in the previous process, the ammonia of the stage (d), the recovery and recycling is carried out by methods already known in the art. For purposes of this invention, the terms "liquid ammonia" and "ammoniacal liquid" as used herein are generally intended to include nitrogen-containing solvents such as liquid ammonia. This will include anhydrous liquid ammonia and ammonia solutions, which comprise small amounts of water. However when used in dissolving metal reactions to form solvated electrons as will be described in more detail below, the ammoniacal liquid is preferably not aqueous. In addition to liquid ammonia, other solvents and co-solvents containing nitrogen may be used that are inert in the presence of solvated electrons. Representative classes include primary amines, secondary amines, tertiary amines, and mixtures of these amines.

Examples of these amines include alkyl amines, such as methylamine, ethyl amine, dimethyl amine, triethyl amine, n-propyl amine, isopropyl amine, tetrahydrofuran (THF), and other solvents or co-solvents that are conveniently inert in the presence of 5 electrons. . Yet a further objective is to provide a further embodiment of the invention for decontaminating land containing nuclear waste, by the steps of: (a) mixing a liquid ammonia or ammoniacal liquid with i / j soil contaminated with nuclear waste in a closed container, for form a dispersion or mud of earth that contains nuclear waste-ammonia; (b) treating the dispersion or slurry of step (a) with solvated electrons upon contact with a reactive metal; (C) allowing soil particles to selectively precipitate from the dispersion or sludge from step (b), to form a lower phase of soil particles while forming an upper solids-liquid phase comprising earth fines suspended in liquid ammonia; 20 (d) separating the upper solids-liquid phase from the inner phase of soil particles, the lower phase of soil particles is sufficiently free of nuclear waste, and (e) separating the ammonia from the earth fines for waste or greater treatment of fines.

While it has been observed that ammonia has the unique ability to form very fine slimes when mixed with earth, it is observed that earth dispersions appear to be further altered by some mechanism that is not understood completely, when it is in the presence of solvated electrons that are formed by dissolving metal reactions with ammonia. That is, by contacting the dispersion of ammoniated earth with either alkali metal or alkaline earth metal, solvated electrons are formed in the mixture, in situ. The solvated V electrons seem that in some cases they optimize the separation of fines from smaller earth. In some cases, when the cross section of particle size is larger than desired, electrons solvated in liquid ammonia appear to provide more demarcation and separation Optimal of the smaller fines that contain nuclear waste materials from other sludge particles. As in the first embodiment of the invention, the second prior embodiment of the invention contemplates the step of recovering and recycling the ammonia of step (e) for re-use. Similarly, the residual solid earth particles precipitated from step (d) are "sufficiently free" of radioisotopes to allow large mass volumes of land to be recycled.

In accordance with this invention, it was also discovered that the above process with ammonia solutions, etc., is equally useful for decontaminating land or lands containing harmful but non-radioactive metals, by the steps of: 5 (a) mixing in a closed vessel an ammoniacal liquid, with a soil or soil contaminated with at least one ion of a metal or noxious metalloid, to form a dispersion or mud; (b) separating a product having ammoniacal liquid from the dispersion or sludge from step (a), to result in a residue of earth sufficiently free of metal or metalloid noxious to allow recovery, and (c) Separate the ammoniacal liquid from the product containing ammoniacal liquid from step (b) to result a waste containing metal or metalloid harmful to waste or further treatment. While not wishing to be supported by any specific mechanism of action involved in separating ions from harmful metals or metalloids from land or land, it has been observed that the target material is frequently soluble in the ammoniacal liquid. In this regard, coordination compounds can be formed in the process of soil washing with ammonia, and possibly from ligand-metal ammonia complexes. Representative metals of these compounds Coordination and complexes may include those from the arsenic, antimony, selenium, cadmium, cobalt, mercury, chromium, lead, and mixtures thereof. Coordination compounds can also be prepared by introducing other ligand complexing agents into the noxious metals containing earth-ammonia mud. These metals can be removed by forming, for example, metal cyanide ligands soluble in ammonia, by adding a source of ions and cyanide, for example sodium cyanide, ammonia cyanide, etc., to the sludge. The separation of the ammonia liquor '"" * > it results in the removal of the noxious metal from the earth fraction. As a further embodiment of the invention, earths containing harmful non-radioactive metals can be decontaminated by the steps of: (a) mixing in a closed vessel an ammoniacal liquid with a soil contaminated with at least one ion of a metal or metalloid that is noxious to form a dispersion or mud; (b) allowing particles of earth to selectively precipitate from the dispersion or sludge from step (a) to provide a lower phase, comprising a precipitate of soil particles while forming a higher liquid-solid phase comprising fines of earth dispersed in the ammoniacal liquid; (c) separating the upper liquid-solid phase from the lower phase, the precipitate of ground particles from the inner phase is sufficiently free from ions of the harmful metal or metalloid, to allow recycling of the soil particles, and (d) separate the ammoniacal liquid of the liquid-solid phase and above to result in a residue comprising the metal or metalloid harmful to waste or further treatment. Still a further object of the invention is to provide a method for treating contaminated soils with mixed waste, wherein the waste may comprise an ion of a harmful non-radioactive metal or metalloid and a nuclear waste, for example. Typically, the nuclear waste is constituted by a radioactive isotope metal or radionuclide. In general, they are intended to include metals from the actinide series, such as uranium, plutonium, thorium and their mixtures. As a further embodiment of the invention, soil contaminated with noxious non-radioactive metals can be decontaminated with ammonia liquids and electrons solvated by the steps of: (a) mixing in a closed vessel an ammoniacal liquid with a soil contaminated with at least one ion of a metal or harmful metalloid, to form a dispersion or sludge; (b) treating the dispersion or sludge from step (a) with solvated electrons upon contact with a reactive metal selected from the group consisting of an alkali metal, alkaline earth metal and aluminum; (c) separating a product containing ammoniacal liquid from the dispersion or sludge from step (b), to result in a residue of earth sufficiently free of ions of the noxious metal or metalloid, to allow recycling of the soil, and (d) ) separating the ammoniacal liquid from the product containing ammoniacal liquid from step (c), to result in a waste containing metal or metalloid that is harmful to waste or further treatment. The method of step (b) can be carried out by circulating at least a portion of the ammoniacal liquid through a branch containing the reactive metal. The solvated electron solution is recirculated back to the closed container to treat the contaminated soil. This aspect of the invention also contemplates the treatment of contaminated soils with mixed waste, i.e. an ion of a harmful non-radioactive metal or metalloid and a nuclear waste, for example. Typically, the nuclear waste comprises a radium nuclide or a radioactive isotopic metal of the series of actinides such as uranium, plutonium, thorium and their mixtures.

The invention is also intended to include mixed wastes comprising an ion of a harmful non-radioactive metal or metalloid and an organic compound, and more particularly, a halogenated organic compound such as PCBs, dioxins and pesticides. BRIEF DESCRIPTION OF THE DRAWINGS For an additional understanding of the invention and its characteristic aspects, reference will now be made to the accompanying drawings in which: Figure 1 is a diagrammatic view of a system for decontaminating earth containing harmful metals by filtration; Figure 2 is a diagrammatic view of a system for separating radionuclides in contaminated soil and concentrating a reduced fraction of soil using solvated electrons as an option. DESCRIPTION OF THE PREFERRED MODALITIES The invention is also related to improved methods for separating unwanted nuclear waste material from land. harmful metals, particularly radionuclides and ionized forms of potentially toxic non-radioactive metals and metalloids such as arsenic, antimony and selenium, by concentrating in some cases on very small particles or fines of earth or clay. Concentrated radionuclide and fines containing ions non-radioactive metals, for example in this way are in a state that allows more efficient disposal, such as by storage or for additional treatment to modify the harmful substances in less toxic and more environmentally benign. The methods are based on the observation that ammonia liquids possess the unique ability to break up lands into very fine mud. It was also found that suspensions of what appears to be extremely fine earth particles can be prepared by mixing with ammonia. Land contaminated with t * rJ radionuclides and land contaminated with harmful non-radioactive metal and metalloid ions or soil contaminated with both, they are preferably mixed with anhydrous liquid ammonia, to form finely dispersed slurries or slurries. Due to the lower ammonia density compared to water, particles of significantly smaller earth are suspended in the liquid, and particles that are otherwise suspended in water are easily precipitated from the dispersion due to the lower density and viscosity of ammonia. The largest volume fraction of the earth consists of precipitated particles larger than are sufficiently free of the radius nuclide or other contaminant to allow recovery of large volumes of the treated soil. It was observed for example that washing earth in ammoniacal solutions, and particularly in liquid ammonia anhydrous, results in significant reduction in concentrations of certain metal ions, even when there are no visible particles in the ammonia after treatment. Accordingly, liquid ammonia is found to be effective in both physical and chemical decontamination improvement to even decompose tightly bonded clays in thin slivers of platelets coupled with a metal transport mechanism to maximize metal contaminant extraction and exposure. , while also serving as a ligand to bind contaminated metals in reactions of complexed or chelated type. The ammoniacal liquid is preferably anhydrous liquid ammonia, but solutions of at least fifty weight percent ammonia in water can also be employed when exclusively ammonia is used. Land contaminated with metal ions and harmful non-radioactive metalloids, such as arsenic and chromium (VI) or land contaminated with mixed waste, such as radioactive isotopic metals, such as uranium, plutonium, and thorium, together with noxious non-radioactive metal ions, they can also be effectively treated by forming dispersions or sludges with anhydrous liquid ammonia, which in turn can be treated with solvated electrons by contacting the earth-ammonia sludge with a reactive metal, particularly a more electropositive metal, such as sodium, potassium, barium and calcium . When a metal such as sodium dissolves into liquid ammonia, it becomes a cation by losing its valence electron as illustrated in the following equation. Na - * Na + + e "The ammonia molecules then reversibly solvate these ions and electrons according to the equations: Na + + xNH3 ** Na (NH3) x + e" + yNH3"and" (NH3) and The "ammoniated electron" , is responsible for the strong reducing properties that are exhibited by these solutions. In this regard, the methods of the invention are suitable for treating soils contaminated with noxious chromium (VI), where the solvated electrons reduce the ions of the oxidation state higher harmful no less harmful chromium (III). The methods as described herein, especially are well suited for the selective separation of lead from earth, particularly when treated with solvated electrons. Solvated electrons are also useful for decontaminating lands that have mixed debris, such as ions of a harmful non-radioactive metal or metalloid, together with polyhalogenated organic compounds such as polychlorinated biphenyls (PCBs), as well as dioxins, for example, 2, 3, 7, 8- tetrachlorodibenzo-p-dioxin, and any of the various other members of the family of chlorinated dioxins and various pesticides. The term "pesticide" is intended to denote any substance, organic or inorganic used to destroy or inhibit the action of plant or animal pests. In this way, pesticides will include insecticides, herbicides, rodenticides, miticides, etc. Accordingly, this aspect of the invention is particularly effective for treating soils contaminated with mixed wastes, by removing and complexing harmful metal ions through the action of ammonia, forming dispersions while simultaneously reducing halogenated compounds in compounds of Less toxicity and impact on the environment Ir "Methods for the destruction of halogenated organic compounds are described in U.S. Patent No. 5,110,364 A general method for decontaminating lands containing harmful non-radioactive metal or metalloid ions with ammoniacal solutions according to the present invention, is illustrated by Figure 1. Earth can first be added to the mixing vessel of Figure 1. Anhydrous liquid ammonia is circulated from the ammonia storage tank and used to fluidize the ammonia. ground resulting in the formation of a fine mud of earth suspended in ammonia. Agitation of the suspension can be provided by circulating the ammonia (a) between the mixing vessel and the ammonia retention tank by pumping means, although other mixing methods can be employed. After the mud has mixed Sufficiently, the ammonia in liquid phase can be separated from the earth by decanting, filtration with pressure (b) or by other known methods. The ammonia in the holding tank containing metal ions is recovered by evaporating the ammonia through the vent, where it is captured for reuse by conventional ammonia collection methods. Methods of the invention can also be performed on land or lands that are predominantly sand, and that are practically free of clay and organic constituents. In this mode, clays that possess ion exchange properties, such as attapulgite, mont-morillonite, kaolinite, are added to the ammonia reaction mixture where the noxious ions are adsorbed by the clay and the metal-clay dispersion is decanted Of the sand. As a further embodiment, the ammoniacal solutions can also employ known complexing / chelating agents such as EDTA, NTA, (nitrilotriacetic acid), 8-hydroxyquinoline, cyanide ions, and so on, which improve the solubility of the metal ions in the solvent to remove harmful metals from the mud of the land. The following specific examples demonstrate the invention, however it will be understood that they are for illustrative purposes only and are not intended to be totally definitive as to the conditions and scope. EXAMPLE I Methods of the invention can be carried out by means of a system as illustrated in Figure 1. A closed reactor 10 is used as a mixing vessel for soil contaminated with nuclear waste 14 placed in the bottom 5 of the container. The term "earth" is intended to have its ordinary meaning, and includes one or more components in varying proportions such as clay, stone, disintegrated rock particles or sand, organic matter together with varying amounts of water and the like. Obviously, compositions of / • ** Earth will vary widely depending on the source and location. For example, desert lands or other arid locations are primarily sandy compositions with little organic matter or clay components. A land representative of the state of Ohio known as black or clay earth of Ohio (Ohio Loa) is found to have an analysis of 35% sand, 32% silt, 33% clay and 4.1% organic matter and has a pH of 7.7. By contrast land in Oak Ridge, TN, is found to contain only 1% sand, 26% silt, 73% clay, no organic matter, and a pH of 5.2. In sum, the term "Land" for purposes of this invention is intended to have a broad compositional composition, including varying ranges of clay, sand particles / disintegrated rock, organic matter, silt fines, moisture and so on. This will include lands that are primarily clay or sand.

Anhydrous liquid ammonia 16 or a liquid ammonia solution containing a small amount of water is introduced to a closed reactor 10 of the ammonia storage vessel 18. Once filled, liquid ammonia is removed from reactor 10 from below the liquid surface by the circulation pump 20 placed on the outlet line 22. The flow of ammonia is directed by a three-way diverter valve 24-25 either over the line 26 or the solvator 28 containing a bed of reactive metal 30., such as alkaline or toric alkaline metals or mixtures thereof. Convenient representative metals include sodium and potassium, lithium, calcium and magnesium. Aluminum would also be a convenient reactive metal. Circulating solvated electrons are formed by circulating ammonia 16 through a metal bed in reactor 28. This avoids the problems associated with injecting metal rods or other metal sources, directly into the reaction vessel 10. Accordingly, methods of the present invention contemplate the option of demarcation and separation of improved particle sizes of radioactive components into fines. of earth and clay with ammonia and electrons solvated in ammonia. Whether ammonia flows through the branch line 26 or through the solvator 28, the solution is recirculated to the bottom of the reactor 10 through the valve 32, forming a fluidized flow pattern in the reactor. This produces a mixing action of the ammonia solution and earth and / or solvated electrons to form a sludge. Once the earth has been uniformly dispersed in the ammonia, the pump 20 is deactivated to allow the dispersion to undergo phase separation, i.e. a lower solid phase and a higher solid-liquid phase. Large particles of the dispersion are precipitated as solid phase 34 at the bottom of reactor 10, and are sufficiently free of radionuclide contaminants, the latter concentrated in a small fraction of earth consisting of fines or silt dispersed in the ammonia solution as the upper solid-liquid phase 36. The fine sludge of suspended particles forming the upper solid phase 36 is removed from the reactor vessel 10 to the evaporator tank 38 via line 40 when the valve 42 is opened. The ammonia 43 is evaporated to separate it of radioactive fines 44. Optionally, ammonia can be transferred via line 48 to compressor 46 for relicting if it is desired to recycle ammonia for further use in the decontamination process. The liquefied ammonia is then transferred to the ammonia storage tank 18 through line 50. EXAMPLE II PART A The decontamination of soil with ammoniacal liquid is demonstrated by the following experiment: A two-kilogram lot of black or clay soil from Ohio (Ohio Loam) was adulterated with low levels of cobalt nitrate. The adulterated earth is analyzed and found to contain 4.5 ppm of cobalt. A 10 gram sample of the adulterated soil is mixed with approximately 80 grams of anhydrous liquid ammonia and stirred until well mixed. The soil or soil is then filtered from the ammonia and sent for analysis. The ammonia is allowed to evaporate from the residue. The analysis of the terrain reveals that the cobalt content has dropped from 4.5 ppm to 1.1 ppm. PART B In order to improve the separation of Co + 2 ions from the ground, this separation is not as efficient as Co + 3, two methods can be used: In the first method, 1.50 equivalents of ethylenediaminetetraacetic acid (EDTA) per Co + 2 ion they mix with the soil and anhydrous liquid ammonia. The soluble COEDTA complex is easily filtered from the soil matrix to reduce the concentration of Co + 2 in the soil to an acceptable level. In a second method, ammonium nitrate (10 gr / 100 gr of soil) is added to a sample of soil or soil and the mixture is stirred with anhydrous liquid ammonia. The solubilized Co + 2 ions are removed together with the ammoniacal solvent before filtration. The toxic impurity and excess ammonium nitrate are isolated by evaporating the solvent and disposed of by methods known in the art.

EXAMPLE III A sample of 150 grams of soil contaminated with both 150ppra of Sr9 ° and 500ppm of polychlorinated biphenyls (PCBs) is placed in reactor 10 (Fig. 2). The reaction is then charged with 1.5 L of liquid ammonia (anhydrous) and pumped through the recirculation loop described in Example I to stir the soil. After a convenient period, the ammonia is allowed to circulate through the solvator 28 to generate a solution of electrons solvated by contact and dissolution of 10 grams of calcium metal 30. The generation of solvated electrons can be a one-time event, in where the metal is completely consumed in a continuous flow of ammonia. Alternatively, the shunt 26 can be used at intervals to interrupt the flow of solvated electrode solution and thus cause the introduction of the reagent to make a sequence of pulses. When an amount of sufficient reactants has been added, the ammonia circulation pump 20 is stopped and the soil sludge is allowed to settle briefly to delineate a bottom phase of larger soil particles, and a suspension of supernatant of soil particles. metal / earth fines / ammonia. This suspension is transferred to tank 38, from which the ammonia can be separated by evaporation leaving the greatly reduced volume of metal material / earth fines for final disposal in accordance with the established local state and federal regulations. The mass of the original earth sample charged to the reactor remains there. The concentration of both radionuclides and PCBs is sufficiently low to allow the treated earth to return as an embankment as allowed by the accepted practices in the field of corrective processes. EXAMPLE IV A soil having a higher clay content than that used in Example I, or a soil having a clay fraction with a cation exchange capacity higher than that used in Example I is adulterated with an arsenic compound . The earth is treated with ammonia as in Example I except that no solution of solvated electrodes is introduced. After agitation and separation of the earth fines, the earth fraction of large particles is sufficiently free from the toxic metalloid to allow its return to a suitable embankment or to the original excavation site. The clay fines containing the arsenic impurity are greatly reduced in volume and can be stored with less volume of space than otherwise required. EXAMPLE V One Earth contaminated with noxious chrome VI ions is mixed with liquid ammonia in a closed reactor and stirred to completely disperse the soil particles. Approximately 1.89 1 (0.5 gallon) of liquid ammonia is used per .453 kg (pound) of soil. A solution of solvated electrons is formed from the reaction of liquid ammonia with calcium metal introduced to the reactor. The metal addition can be an injection in an event or by a serial addition mode. When the typical blue color of sulfated electrons persists, the addition of more metal is concluded. After a few minutes to ensure complete reaction, the solvated electrode solution is neutralized. The ammonia is allowed to evaporate and ver for additional use. The earth has all the chromium ions now with an oxidation number less than VI, for example chromium III ions are in convenient form for cling without further corion. EXAMPLE VI A sample of 500 grams of sand contaminated with plutonium compounds is made up of sludge with 1.0 1 and anhydrous liquid ammonia in a reaction apparatus such as that illustrated in Figure 1. Agitation is stopped and the sand is quickly sedimented to reveal a transparent ammonia layer due to the lack of fine-sized particles. The ammonia is decanted and found to contain very few dissolved plutonium compounds, showing that very little change has occurred in the level of plutonium compounds in the sand.

For comparison purposes, 25 grams of mont-morillonite clay are added to the reactor and the clay-sand mixture is resuspended in 1.0 1 anhydrous liquid ammonia. Stirring is continued for a previously illustrated time that allows the clay to adsorb the proton ions. Stirring is stopped and then the sand quickly sediments leaving a clay / ammonia suspension on it. The suspension is removed by decanting. Since some of the clay / ammonia suspension remains in the reactor, additional ammonia is added and the sequence of agitation, sedimentation and decantation is repeated until the amount of clay loaded with plutonium is reduced in the desired ratio. The treated sand is removed for proper disposal. The clay is released from the ammonia when the liquid evaporates. The clay solids are discarded in a prescribed manner for materials contaminated with plutonium. Due to the reduced volume of waste, handling and disposal are more efficient. EXAMPLE VII 150 grams of soil contaminated with cadmium salts (144 ppm Cd + 2) are treated with 1.5 liters of anhydrous liquid ammonia in a pressure pump with a capacity of 3 liters. 8.5 grams of sodium cyanide are added and the mixture is stirred for one to two hours at room temperature. The mixture is filtered. The largest volume portion of the earth remains in the filter and the smaller earth fines pass. Both lots of soil are released from ammonia by evaporation in open containers. The largest dirt particles in the filter (19.5 grams of filter cake) are found to only have 38 ppm of Cd + 2 ions. The earth fines that pass through the filter contain 116 ppm of Cd + 2 ions. This represents 90 percent of the original amount of cadmium on earth. This example demonstrates the ability of an ammoniacal and cyanide liquid to remove and concentrate ions of harmful metals in small fractions of soil particles. In this way, the methods of the disclosed invention provide the advantages of separating nuclear waste and / or non-radioactive harmful metal or metalloid ions by smaller particles, comprising using water-based systems; allow recycling of ammonia that otherwise would not be achieved with systems that rely on more expensive purification chemicals; provides means for easily separating fines from liquid ammonia; it removes transport and storage of water to desert sites, and provides additional means to control particle sizes within a predetermined range with solvated electrons. While the invention has been described in conjunction with various embodiments, they are illustrative only. Accordingly, many alternatives, modifications and variations to people skilled in the art will be apparent in light of the above detailed description, and therefore it is intended to encompass all these alternatives and variations that fall within the spirit and broad scope of the appended claims.

Claims (43)

1. CLAIMS 1. - A method to decontaminate a land containing harmful metals, characterized by the steps of: (a) mixing in a closed container, an ammoniacal liquid with a soil or soil contaminated with at least one ion of a metal or a metalloid harmful to form a dispersion or mud; (b) separating a product containing ammoniacal liquid from the dispersion or sludge from step (a), to result in a residue of earth sufficiently free of metal or metalloid noxious ions to allow recovery and (c) separate the ammoniacal liquid of the product containing ammoniacal liquid from step (b) to result in a waste containing metal or metalloid that is harmful for further disposal or treatment.
2. 2. The method according to claim 1, characterized in that the ammonia liquid is anhydrous liquid ammonia or a solution containing ammonia.
3. 3. The method according to claim 2, characterized in that the ion of the harmful metal or metalloid is a member selected from the group consisting of radioactive metals, non-radioactive metals and their mixtures.
4. 4. The method according to claim 2, characterized in that the ion of the harmful metal or metalloid is non-radioactive and is a member selected from the group consisting of arsenic, antimony, selenium, cadmium, cobalt, mercury, chromium, lead, and its mixtures.
5. 5. The method according to claim 2, characterized in that the product containing ammoniacal liquid of step (b) comprises a coordination compound formed from the ion of a non-radioactive metal or metalloid and ammonia.
6. 6. The method according to claim 5, characterized in that the coordination compound is a metal-ammonia ligand complex.
7. The method according to claim 2, characterized in that the product containing ammoniacal liquid r ^ of step (b) comprises a coordination compound formed from the ion of the noxious metal or metalloid and cyanide ion.
8. 8. The method according to claim 1, further characterized by the step of recycling the ammoniacal liquid of step (c).
9. 9. The method according to claim 1, further characterized by the addition of a chelating agent to the closed container.
10. 10. The method according to claim 1, characterized in that the contaminated land comprises 20 mainly sand and includes the stage of adding a clay to the container.
11. 11. A method for decontaminating a soil containing harmful metals, characterized by the steps of: (a) mixing in a closed vessel, an ammoniacal liquid with a 25 soil or soil contaminated with at least one ion of a metal or a harmful metalloid to form a dispersion or sludge; (b) allowing soil particles to selectively precipitate from the dispersion or sludge from step (a), to provide a lower phase comprising a precipitate of soil particles, while forming an upper liquid-solid phase comprising fine earth dispersed in the ammoniacal liquid; (c) separating the upper solid-liquid phase from the lower phase, the precipitate of ground particles from the lower phase is sufficiently free of ions of the harmful metal or metalloid to allow recovery of the soil particles and (d) separate the ammonia liquid from the upper solids-liquid phase to result in a waste containing metal or metalloid that is harmful for further disposal or treatment.
12. The method according to claim 11, characterized by the additional step of recovering and recycling the ammoniacal liquid of step (d).
13. The method according to claim 11, characterized in that the ammoniacal liquid of step (a) is anhydrous liquid ammonia or a solution containing ammonia.
14. The method according to claim 11, characterized in that the ion of the harmful metal or metalloid is a member selected from the group consisting of radioactive metals, non-radioactive metals and their mixtures.
15. 15. The method according to claim 11, characterized in that the ion of the noxious metal or metalloid is not radioactive and is a member selected from the group consisting of arsenic, antimony, selenium, cadmium, cobalt, mercury, chromium, lead, and mixtures thereof .
16. The method according to claim 14, characterized in that the soil comprises a member selected from the group consisting of clay, disintegrated rock, sand, organic material and their mixtures.
17. 17. The method according to claim 11, further characterized by the addition of a chelating agent to the closed container.
18. 18. The method according to claim 11, further characterized by the addition of a complexing agent 15 ligand to the closed container.
19. 19. The method according to claim 18, characterized in that the ligand complexing agent is a salt or compound that produces cyanide ion.
20. The method according to claim 11, characterized in that the earth is primarily sand and the step (a) includes the addition of a clay to the closed container.
21. 21. The method according to claim 11, characterized in that the ground of step (a) comprises a 25 mixed waste.
22. 22. The method according to claim 21, characterized in that the mixed waste comprises an ion of a harmful non-radioactive metal or metalloid and a nuclear waste.
23. 23. The method according to claim 21, characterized in that the mixed waste comprises an ion of a noxious non-radioactive metal or metalloid, and an ion of a radioactive isotopic metal.
24. 24. The method according to claim 22, characterized in that the nuclear waste comprises at least one radionuclide.
25. 25. The method according to claim 24, characterized in that the radionuclide is a member of the actinide series.
26. 26. The method according to claim 23, characterized in that the radioactive isotope metal is a member selected from the group consisting of uranium, plutonium, thorium and mixtures thereof.
27. 27. A method for decontaminating a land, characterized by the steps of: (a) mixing in a closed container, an ammoniacal liquid with a soil or soil contaminated with at least one ion of a metal or a harmful metalloid to form a dispersion or mud; (b) treating the dispersion or sludge from step (a) with solvated electrons, by contacting a reactive metal selected from the group consisting of alkali metal, alkaline earth metal and aluminum; (c) separating a product containing ammoniacal liquid from the dispersion or sludge from step (b), to result in a residue of earth sufficiently free of ions of the harmful metal or metalloid to allow recycling of the soil or soil, (d) ) separating the ammoniacal liquid from the product containing ammoniacal liquid from step (c), to result in a waste containing metal or metalloid that is harmful to waste or further treatment.
28. The method according to claim 27, characterized in that step (b) is carried out by circulating at least a portion of ammoniacal liquid through a derivation containing the reactive metal to form solvated electrons, which are recirculated to the closed container. to treat contaminated soil.
29. 29. The method according to claim 27, characterized in that the ion of the harmful metal or metalloid is a member selected from the group consisting of radioactive metals, non-radioactive metals and their mixtures.
30. 30. The method according to claim 29, characterized in that the ammoniacal liquid of step (a) is anhydrous liquid ammonia or a solution containing ammonia.
31. The method according to claim 29, characterized in that the ion of the noxious metal or metalloid is not radioactive, and is a member selected from the group consisting of arsenic, antimony, selenium, cadmium, cobalt, mercury, chromium, lead, and its mixtures.
32. 32. The method according to claim 30, characterized in that the earth is contaminated with chromium VI, and is reduced by the solvated electrons.
33. 33. The method according to claim 29, characterized in that the soil comprises a member selected from the group comprising clay, disintegrated rock, sand, organic material and their mixtures.
34. 34. The method according to claim 29, characterized in that the earth is primarily sand and the step (a) includes the addition of a clay to the container.
35. 35. The method according to claim 27, characterized in that the soil in step (a) comprises a mixed waste.
36. 36. The method according to claim 35, characterized in that the mixed waste comprises an ion of a non-radioactive noxious metal or metalloid and a nuclear waste.
37. 37. The method according to claim 35, characterized in that the mixed waste comprises an ion of a non-radioactive noxious metal or metalloid and ion of a radioactive isotope metal.
38. 38. The method according to claim 36, characterized in that the nuclear waste comprises at least one radionuclide.
39. 39. The method according to claim 38, characterized in that the radionuclide is a member of the actinide series.
40. 40. The method according to claim 39, characterized in that the radioactive isotopic metal is a member selected from the group consisting of uranium, plutonium, thorium and their mixtures.
41. 41. The method according to claim 35, characterized in that the mixed waste comprises an ion of a noxious metal or metalloid and an organic compound.
42. 42. The method according to claim 41, characterized in that the organic compound is a halogenated organic compound.
43. 43. The method according to claim 42, characterized in that the halogenated organic compound is a member selected from the group consisting of PCBs, dioxin and pesticides.