WO2010056742A1 - Retrait de matériaux cibles à l'aide de terres rares - Google Patents

Retrait de matériaux cibles à l'aide de terres rares Download PDF

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Publication number
WO2010056742A1
WO2010056742A1 PCT/US2009/064023 US2009064023W WO2010056742A1 WO 2010056742 A1 WO2010056742 A1 WO 2010056742A1 US 2009064023 W US2009064023 W US 2009064023W WO 2010056742 A1 WO2010056742 A1 WO 2010056742A1
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WIPO (PCT)
Prior art keywords
target material
fixing agent
rare earth
arsenic
stream
Prior art date
Application number
PCT/US2009/064023
Other languages
English (en)
Inventor
John Burba
Carl Hassler
Charles Whitehead
Joseph Lupo
Brock Conrad O'kelley
Robert Cable
Joseph Pascoe
Brandt Wright
Original Assignee
Molycorp Minerals Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Molycorp Minerals Llc filed Critical Molycorp Minerals Llc
Priority to CA2743304A priority Critical patent/CA2743304A1/fr
Priority to AU2009314130A priority patent/AU2009314130B2/en
Priority to EP09826668.7A priority patent/EP2364276A4/fr
Priority to MX2011004929A priority patent/MX2011004929A/es
Priority to JP2011535788A priority patent/JP2012508106A/ja
Priority to CN200980154088XA priority patent/CN102272061A/zh
Publication of WO2010056742A1 publication Critical patent/WO2010056742A1/fr
Priority to ZA2011/04047A priority patent/ZA201104047B/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/103—Arsenic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/06—Controlling or monitoring parameters in water treatment pH
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/16—Regeneration of sorbents, filters

Definitions

  • the invention relates generally to removal, using rare earth metals, of target materials and particularly to removal and stabilization, using rare earth metals, of arsenic.
  • Harmful metals such as arsenic, oxyanions of heavy metals, and their radioactive isotopes, naturally occur in a variety of combined forms in the earth. Their presence in natural waters may originate, for example, from geochemical reactions, industrial waste discharges (including those generated by nuclear, oil, and/or coal fired power plants), or agricultural, industrial, and/or home uses of pesticides, herbicides, insecticides, and rodenticides, and other sources. Because the presence of high levels of certain harmful metals, particularly arsenic, may have carcinogenic and other deleterious effects on living organisms, the U.S. Environmental Protection Agency (“EPA”) and the World Health Organization have set the maximum contaminant level (“MCL”) for various harmful metals in drinking water.
  • MCL maximum contaminant level
  • Arsenite in which the arsenic exists in the +3 oxidation state, is only partially removed by adsorption and precipitation technologies because the predominate form of arsenite is arsenious acid (HAsO 2 ).
  • Arsenious acid is a weak acid and maintains a neutral charge (that is, contains minimal, if any, arsenite (AsO 2 "1 )) at a pH between pH 5 and pH 8 where adsorption takes place most effectively.
  • Arsenic is often dissolved selectively from the solid wastes and isolated from streams using a co-precipitation process.
  • This process uses iron reagents to precipitate arsenic as ferric arsenate.
  • This precipitation method requires a series of pH adjustments to form and, in many applications, produces an excessively large volume of, the ferric arsenate precipitate.
  • Precipitation using rare earth metals is a newly invented technology that has shown promise removing harmful and/or valuable metals from contaminated waste streams.
  • Cerium in particular, has been used to remove oxyanions of various harmful metals, such as arsenic, antimony, molybdenum, tungsten, vanadium, and uranium. There is a need for a process to remove harmful and/or valuable metals effectively from solids and/or liquid streams.
  • This disclosure relates generally to target material removal from fluids and stabilization of the removed target material.
  • a process includes the steps of:
  • the insoluble target material-containing composition is typically in the form of precipitate that can be removed as a solid.
  • the insoluble target material-containing composition has at least about 0.01 wt. %, even more preferably at least about 0.1 wt. %, and even more preferably ranges from about 5 to about 50 wt. % of the target material.
  • the target material is commonly in the form of an oxygen-containing anion with an oxyanion being illustrative.
  • the soluble fixing agent, or precipitant can be supported by a suitable carrier or be unsupported.
  • a process includes the steps: (a) providing an arsenic and a valuable metal-containing solid material; (b) contacting the solid material with a leaching agent to form a leach stream comprising dissolved arsenic and an arsenic depleted solid, the dissolved arsenic comprising most of the arsenic contained in the solid material and the arsenic depleted solid comprising most of the valuable product contained in the solid material; (c) contacting the leach stream with a soluble fixing agent to form a target material-containing composition comprising most of the arsenic in the leach stream and the soluble fixing agent; and
  • the fixing agent can be in any suitable form, such as a solid, a coating, a particle, a nano-particle, a sub-micron particle, a dissolved rare earth species, and/or powder.
  • the rare earth can be in the form of a solid, or the solid may be supported by a polymeric binder interconnecting particles of the rare earth-containing compound.
  • the coating can be on any suitable carrier.
  • the fixing agent is a lanthanoid, particularly cerium.
  • the cerium is typically in the form of a cerium (IV) oxide or a dissolved cerium species, which, for example, can be a cerium (III) and/or (IV) salt solution.
  • the valuable product can be any metal or metalloid, with a transition metal, aluminum, tin, and lead being typical and titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, molybdenum, a platinum group metal, a precious metal, and mixtures thereof being even more typical.
  • a solid-phase composition that includes:
  • the lattice structure of the crystalline phase is believed to belong to a trigonal space group.
  • the composition is substantially crystalline, with the arsenic, oxygen, rare earth element, and water of hydration forming a crystal lattice.
  • a method includes the steps of: (a) providing a target material-containing stream;
  • non-rare earth salt additive comprising a non-rare earth metal in the +3 oxidation state and being substantially free of a rare earth
  • the non-rare earth metal can be any non-rare earth metal in the +3 oxidation state, with transition metals, boron, aluminum, gallium, indium, thallium, and bismuth being preferred, and the transition metals and aluminum being particularly preferred.
  • Preferred transition metals include the elements having atomic numbers 22-29, 40-45, 47, 12-11 , and 79.
  • the first salt additive is, in one formulation, a bimetallic, lanthanide -based salt solution.
  • the first salt additive includes cerium in the +3 oxidation state and aluminum in the +3 oxidation state.
  • the second salt additive in a preferred formulation, contains aluminum in the +3 oxidation state.
  • the first and second salt additives can provide significant reductions in the amount of rare earths required to remove selected target materials, particularly arsenic.
  • a process is provided that includes the steps of:
  • first and second fixing agents are used.
  • the feed comprises a target material-bearing aqueous solution, having a first concentration of target material.
  • the target-bearing aqueous solution is contacted with an insoluble first fixing agent, such as an adsorbent or absorbent, to produce a target material- bearing first fixing agent.
  • the first step removes most, if not all, of the target material from the target material-bearing aqueous solution.
  • the target material- bearing first fixing agent is contacted with an alkaline stripping solution ("release agent") to produce an intermediate target material-rich solution having a second concentration of the target material.
  • the second concentration of target material may exceed the first concentration of target material.
  • the alkaline stripping solution can be or include, for example, the leaching agent discussed above.
  • the second concentration of target material is a concentration about equal to the solubility limit of the target material (at the process conditions of the second step). More commonly the second concentration of the target material is between about 0.1 and about 2,500 g/L, even more commonly between about 0.1 and about 1,000 g/L, and even more commonly between about 0.25 g/L and about 500 g/L.
  • a soluble or dissolved second fixing agent is contacted with the intermediate target material-rich solution in an amount sufficient to precipitate most, if not all, of the target material as a target material-bearing solid.
  • the target material- bearing solid may be separated from the intermediate solution by any suitable solid/liquid separation technique to produce a separated solid for disposal and a stripping solution for recycle to the second step.
  • the insoluble first fixing agent is commonly a particulate solid.
  • the first fixing agent preferably is an insoluble rare earth metal compound, preferably an insoluble rare earth oxide comprising an insoluble rare earth compound, such as hydrous or anhydrous rare earth oxides, fluorides, carbonates, fluorocarbonates, silicates, and the like.
  • a particularly preferred first fixing agent is CeO 2 .
  • the first fixing agent is particularly effective in removing arsenic having an oxidation state of +3 or +5.
  • the soluble second fixing agent typically has an oxidation state lower than the oxidation state of the first fixing agent.
  • the oxidation state of the second fixing agent is one of +3 or +4.
  • the soluble fixing agent preferably is a soluble rare earth metal compound and more preferably includes salts comprising rare earth compounds, such as bromides, nitrates, phosphites, chlorides, chlorites, chlorates, nitrates, and the like. More preferably, the soluble fixing agent is a rare earth (III) chloride.
  • the target material will be present in a reduced oxidation state and this condition might be undesirable. In such cases, an oxidant may be contacted with the solution to increase the target material oxidation state. Using arsenic as an example, the presence of arsenite might favor the use of an oxidant before the fixing agent is applied.
  • the intermediate solution can include a residual valuable product.
  • the valuable product is commonly any metal of interest, more commonly includes one or more of the transition metals and even more commonly includes a metal selected from the group of metals consisting of copper, nickel, cobalt, lead, precious metals, and mixtures thereof. All or a portion of the residual valuable product may be recovered from the intermediate solution.
  • a method that includes the steps of:
  • a target material-containing stream comprising a dissolved target material and dissolved valuable product, the target material being in the form of an oxyanion and the valuable product being at least one of a transition metal, aluminum, tin, and lead and in a form other than an oxyanion;
  • the present invention can include a number of advantages depending on the particular configuration.
  • the process of the present invention can remove variable amounts of target materials as needed to comply with application and process requirements.
  • the target material removal process can remove high concentrations of target materials to produce a treated solution having no more than about 500 ppm, in some cases no more than about 100 ppm, in other cases no more than about 50 ppm, in still other cases no more than about 20 ppb, and in still other cases no more than about 1 ppb target material.
  • the insoluble rare earth/target material product can be qualified as non-hazardous waste.
  • the target material removal process can be relatively insensitive to pH.
  • the disclosed process can effectively fix target materials, particularly arsenic, from solutions over a wide range of pH levels, as well as at extremely high and low pH values.
  • this capability can eliminate the need to alter and/or maintain the pH of the solution within a narrow range when removing the target material.
  • the aqueous solution is produced from the remediation of an arsenic-bearing material, it adds flexibility because the selection of materials and processes for leaching arsenic from an arsenic-bearing material can be made without significant concern for the pH of the resulting arsenic- containing solution.
  • elimination of the need to adjust and maintain pH while fixing arsenic from an arsenic-containing solution can provide significant cost advantages.
  • the target material removal process can also be relatively insensitive to target material concentration.
  • the process can remove relatively low and high levels of target materials, particularly arsenic, from aqueous streams.
  • the process can be a robust, versatile process.
  • the term “a” or “an” entity refers to one or more of that entity.
  • the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein.
  • the terms “comprising”, “including”, and “having” can be used interchangeably.
  • absorption refers to the penetration of one substance into the inner structure of another, as distinguished from adsorption.
  • adsorption refers to the adherence of atoms, ions, molecules, polyatomic ions, or other substances of a gas or liquid to the surface of another substance, called the adsorbent.
  • the attractive force for adsorption can be, for example, ionic forces such as covalent, or electrostatic forces, such as van der Waals and/or London's forces.
  • each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C", “one or more of A, B, or C" and "A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together.
  • composition refers to one or more chemical units composed of one or more atoms, such as a molecule, polyatomic ion, chemical compound, coordination complex, coordination compound, and the like.
  • bonds and/or forces such as covalent bonds, metallic bonds, coordination bonds, ionic bonds, hydrogen bonds, electrostatic forces (e.g., van der Waal's forces and London's forces), and the like.
  • insoluble refers to materials that are intended to be and/or remain as solids in water and are able to be retained in a device, such as a column, or be readily recovered from a batch reaction using physical means, such as filtration. Insoluble materials should be capable of prolonged exposure to water, over weeks or months, with little ( ⁇ 5%) loss of mass.
  • oxyanion or oxoanion is a chemical compound with the generic formula A x O/ (where A represents a chemical element other than oxygen and O represents an oxygen atom).
  • A represents metal, metalloid, and/or Se (which is a non-metal), atoms.
  • metal-based oxyanions include chromate, tungstate, molybdate, aluminates, zirconate, etc.
  • metalloid-based oxyanions include arsenate, arsenite, antimonate, germanate, silicate, etc.
  • particle refers to a solid or microencapsulated liquid having a size that ranges from less than one micron to greater than 100 microns, with no limitation in shape.
  • precipitation refers not only to the removal of target material- containing ions in the form of insoluble species but also to the immobilization of contaminant-containing ions on or in insoluble particles. For example, “precipitation” includes processes, such as adsorption and absorption.
  • rare earth refers to one or more of yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium erbium, thulium, ytterbium, and lutetium.
  • lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium erbium, thulium, ytterbium, and lutetium are known as lanthanoids.
  • soluble refers to materials that readily dissolve in water. For purposes of this invention, it is anticipated that the dissolution of a soluble compound would necessarily occur on a time scale of minutes rather than days. For the compound to be considered to be soluble, it is necessary that it has a significantly high solubility product such that upwards of 5 g/L of the compound will be stable in solution.
  • sorb refers to adsorption and/or absorption.
  • Figs. IA and B depict a process flow chart according to a first embodiment
  • Fig. 2 depicts a process flow chart according to a second embodiment
  • Fig. 3 is a plot of loading capacity (mg/g) (vertical axis) versus arsenic concentration (g/L) (horizontal axis);
  • Fig. 4 is a plot of final arsenic concentration (mg/L) (vertical axis) versus molar ratio of cerium: arsenic (horizontal axis);
  • Fig. 5 is a plot of final arsenic concentration (mg/L) (vertical axis) versus molar ratio of cerium to arsenic (horizontal axis);
  • Fig. 6 is a series of XRD patterns for precipitates formed upon addition of Ce (III) or Ce (IV) solutions to sulfide-arsenite solutions and sulfate-arsenate solutions;
  • Fig. 7 is a plot of arsenic sequestered (micromoles) (vertical axis) and cerium added (micromoles) (horizontal axis);
  • Fig. 8 is a series of XRD patterns exhibiting the structural differences between gasparite (CeAsO 4 ) and the novel trigonal phase CeAsO 4 • (H 2 O) x ;
  • Fig. 9 is a plot of residual arsenic concentration (mg/L) (vertical axis) versus molar ratio Ce/ As (horizontal axis); and Fig. 10 is a plot of loading capacity (As mg CeO 2 g) (vertical axis) versus molar ratio (Ce/ As) (horizontal axis);
  • Fig. 11 is a plot of residual arsenic concentration (mg/L) (vertical axis) versus molar ratio (horizontal axis);
  • Fig. 12 is a series of XRD patterns exhibiting the structural differences among trigonal CeAsO 4 • (H 2 O) x (experimental), trigonal CeAsO 4 • (H 2 O) x (simulated), and trigonal BiPO 4 ⁇ (H 2 O) 0 67 (simulated).
  • the present invention uses an insoluble or soluble fixing agent or both to remove selected target materials from an aqueous solution.
  • the fixing agent whether soluble or insoluble, preferably includes a rare earth.
  • Specific examples of such materials that have been described as removing arsenic include lanthanum (III) compounds, soluble lanthanum metal salts, lanthanum oxide, cerium dioxide, and soluble cerium salts.
  • insoluble cerium fixing agents remove effectively arsenic, when part of a complex multi-atomic unit having an oxidation state preferably of +3 or higher and even more preferably a oxidation state from +3 to +5, while soluble cerium fixing agents remove effectively arsenic, when part of a complex multi-atomic unit, having an oxidation state of +5.
  • Target materials preferably includes not only arsenic but also elements having an atomic number selected from the group of consisting of atomic numbers 5, 9, 13, 14, 22 to 25, 31, 32, 33, 34, 35, 40 to 42, 44, 45, 49 to 53, 72 to 75, 77, 78, 80, 81, 82, 83, 85, 92, 94, 95, and 96 and even more preferably from the group consisting of atomic numbers 5, 13, 14, 22 to 25, 31, 32, 33, 34, 40 to 42, 44, 45, 49 to 52, 72 to 75, 77, 78, 80, 81, 82, 83, 92, 94, 95, and 96.
  • atomic numbers include the elements of arsenic, aluminum, astatine, bromine, boron, fluorine, iodine, silicon, titanium, vanadium, chromium, manganese, gallium, thallium, germanium, selenium, mercury, zirconium, niobium, molybdenum, ruthenium, rhodium, indium, tin, antimony, tellurium, hafnium, tantalum, tungsten, rhenium, iridium, platinum, lead, uranium, plutonium, americium, curium, and bismuth.
  • Uranium with an atomic number of 92 is an example of a target material having radioactive isotope.
  • target materials amenable to removal and stabilization by the insoluble fixing agent include, without limitation, target materials in the form of complex anions, such as metal, metalloid, and selenium oxyanions.
  • the fixing agent reacts with an aqueous solution comprising one or more target material-containing oxyanions to form a purified aqueous stream.
  • the fixing agent can be soluble or in the aqueous solution under standard conditions (e.g., STP).
  • the fixing agent can comprise a mixture of fixing agents, the mixture comprising soluble or insoluble fixing agents.
  • the fixing agent reacts with one or more of the target material-containing oxyanions, oxyanion radioactive isotopes, or other toxic elements in an aqueous feed to form insoluble species with the fixing agent.
  • the insoluble species are immobilized, for example, by precipitation, thereby yielding a treated and substantially purified aqueous stream.
  • the target material-containing solid 100 includes one or more target materials and, optionally, a valuable product (which may itself fall within the definition of a target material), such as a transition metal (such as nickel, cobalt, copper, a precious metal (such as, gold, and silver) and/or a platinum group metal (such as, ruthenium, rhodium, palladium, osmium, iridium, and platinum, aluminum, tin, and lead).
  • a target material such as a transition metal (such as nickel, cobalt, copper, a precious metal (such as, gold, and silver) and/or a platinum group metal (such as, ruthenium, rhodium, palladium, osmium, iridium, and platinum, aluminum, tin, and lead).
  • a target material such as a transition metal (such as nickel, cobalt, copper, a precious metal (such as, gold, and silver) and/or a platinum group metal (such as, ruthenium
  • Examples of the solid 100 include products, byproducts and waste materials from industries such as: mining; metal refining; steel manufacturing; glass manufacturing; metal working processing and/and manufacturing; chemical and petrochemical production, processing and manufacturing; as well as contaminated soil, wastewater sludge, and process stream remediation and the like.
  • Specific examples of target material-bearing solids 100 include ores, mine or mill tailings, concentrates, calcines, slag, and mattes, and spent catalysts.
  • the target material-containing solid 100 is derived from an electrolyte, stripping solution, or leach solution containing dissolved nickel in a concentration of from about 5 mg/L to about 1,000 g/L nickel, chlorine in a concentration of from about 5 mg/L to about 1 ,000 g/L, sulfate in a concentration of from about 5 mg/L to about 5,000 g/L, arsenic (III) in a concentration of from about 1 to about 1,500 mg/L, cobalt in a concentration of from about 5 to about 5,000 mg/L, copper in a concentration of from about 0.1 to about 1,500 mg/L, sodium in a concentration of from about 1 to about 1,500 mg/L, and lead in a concentration of from about 10 mg/L to about 1,500 g/L.
  • an electrolyte, stripping solution, or leach solution containing dissolved nickel in a concentration of from about 5 mg/L to about 1,000 g/L nickel, chlorine in a concentration of from about 5 mg/L to about 1
  • the target material-containing solid 100 is derived by contacting, such as by sparging, a reductant, preferably H 2 S, through the solution.
  • a reductant preferably H 2 S
  • the resulting target material-containing solid 100 typically includes from about 1 to about 10 wt. % AS 2 S 3 , from about 25 to about 75 wt. % CuS, from about 0.1 to about 2.5 wt. % lead, and from about 1 to about 25 wt. % NiS.
  • the target material-containing solid 100 is contacted with an aqueous leaching agent to dissolve the target material (and optionally the valuable product) and form a target material-containing stream 108.
  • the aqueous leaching agent can be any acidic (e.g., pH less than about pH 7) or alkaline (e.g., pH more than about pH 7) leach solution that is capable of dissolving, from the target material-containing solid 100, at least most of the target material.
  • leaching agents include inorganic salts (e.g., alkali and alkaline earth metal phosphates, chlorides, nitrates, sulfates, and chlorates), inorganic acids (e.g., mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid), organic salts (e.g., citrate and acetate), organic acids (e.g., citric acid and acetic acids), and alkaline agents (e.g., hydroxide, cyanide, thiosulfate, and thiourea).
  • the leaching agent is a base, such as a carbonate (XCO 3 ), bicarbonate
  • X is normally an alkali or alkaline earth metal.
  • the alkaline solution includes a leaching agent in an amount of less than about 25 % by wt, even more preferably less than about 20 wt. %, and even more preferably ranges from about 1 to about 15 wt. %, with about 5 wt. % being preferred.
  • the aqueous leaching agent selectively dissolves most of the arsenic while leaving most of the valuable product in the solid material. While not wishing to be bound by any theory, it is believed that the caustic leaching agent metastasizes with copper to form soluble arsenic compounds.
  • the arsenic-containing aqueous leaching agent commonly includes from about 15 to about 25 g/L Na 2 CC> 3 , 1 to about 30 g/L arsenic (III), from about 1 to about 10 g/L sulfur (e.g., as sulfide, sulfate, and/or sulfite), no more than about 5 g/L chlorine, no more than about 10 mg/L nickel, and no more than about 5 mg/L copper.
  • the pH of the resulting solution is typically about pH 9 or higher and even more typically ranges from about pH 9 to about pH 12.
  • the target material-containing stream 108 is separated from the target material- depleted solid by any well known liquid/solid separation technique. Solid/liquid separation is commonly performed by a number of techniques, including filtering, hydrocycloning, screening, centrifuging and gravity separating techniques, such as by counter current decantation and settling.
  • the target material-containing stream 108 typically contains a concentration of dissolved or otherwise solubilized target material ranging from about 0.1 g/L up to the solubility limit of the material in the stream under the conditions of the stream.
  • the target material-containing stream concentration ranges from about 0.1 g/L to about 1 ,000 g/L, even more typically the target material concentration ranges from about 0.1 to about 500 g/L, and even more typically the target material concentration ranges from about 0.1 g/L to about 100 g/L.
  • Optional step 112 adjusts the charge of most and even more preferably of about 75% or more of the target material or a composition incorporating the target material to a selected charge.
  • the target material is arsenic
  • the preferred oxidation state may be +5 because the soluble fixing agent may not form a precipitate with the arsenic at other arsenic oxidation states, specifically -3 (arsenides) and +3 (arsenites).
  • the oxidation state can be adjusted by any suitable oxidation and/or reduction technique and/or using any suitable oxidant and/or reductant.
  • a non- limiting example of a preferred oxidant is a molecular oxygen-containing gas. The molecular oxygen-containing gas is normally sparged through the target material-containing stream.
  • the concentration of the target material in the target material- containing stream may be increased by suitable techniques, such as through water removal.
  • Water may be removed, for example, by evaporation, distillation, and/or filtration techniques (such as, membrane filtration).
  • Other techniques include precipitation and redissolution, absorption or adsorption followed by stripping, ion exchange followed by stripping, and the like of the target material.
  • interferors which interfere with removal of the target material
  • fluorides, phosphates, carbonates, silicates, and vanadium oxides are removed from the target material-containing stream by suitable techniques, such as ion exchange, membrane filtration, precipitation, a complexing agent, and the like.
  • Interferors can compete with other target materials, particularly arsenic, for available fixing agents, thereby increasing fixing agent consumption and/or lowering levels of target material removal.
  • the concentration of interferors is maintained preferably at a concentration of no more than about 300 ppm/interferor species and even more preferably no more than about 10 ppm/interferor species.
  • the target material-containing stream 100 is contacted with a soluble fixing agent to form a precipitate-containing solution 120 containing a target metal- containing precipitate 128.
  • a soluble fixing agent is preferably one or more of scandium, yttrium, and a lanthanoid and is in a form that is soluble in water and/or the aqueous leaching agent.
  • the soluble fixing agent comprises cerium, it typically has an oxidation state of +4 or less.
  • the fixing agent can be, without limitation, a soluble salt, such as bromides, nitrates, phosphites, chlorides, chlorites, chlorates, and the like of scandium, yttrium, or a lanthanoid, with a chloride of cerium (III) or cerium (IV) being preferred. While not wishing to be bound by any theory, it is believed that soluble forms of cerium (IV) can form nanocrystalline cerium dioxide, which then sorbs target materials or a composition incorporating the target material.
  • a soluble salt such as bromides, nitrates, phosphites, chlorides, chlorites, chlorates, and the like of scandium, yttrium, or a lanthanoid
  • a chloride of cerium (III) or cerium (IV) being preferred. While not wishing to be bound by any theory, it is believed that soluble forms of cerium (IV) can form nanocrystalline cerium dioxide, which then sorbs target materials or a composition incorporating
  • the soluble fixing agent is added, commonly as a separate aqueous solution, to the target material-containing stream preferably in an amount to produce an average molar ratio of fixing agent to target material in solution of less than about 8 : 1 and more preferably ranging from about 0.5:1 to about 5:1.
  • the pH of the target material-containing stream preferably ranges from about pH 4 to about pH 9 and even more preferably from about pH 5.5 to about pH 8. In some instances, a pH adjustment may be required before step 116.
  • the pH when too high or too low, can cause the soluble fixing agent (discussed below) to precipitate out of solution (e.g., when the pH is too high, the fixing agent can precipitate out of solution as a carbonate or hydroxide and when the pH is too low the fixing agent can precipitate out of solution as a sulfate).
  • a chelating agent can be added to the soluble fixing agent aqueous solution to increase the solubility of the fixing agent in the aqueous solution.
  • a typical chelating agent is a chemical compound containing at least two nonmetal entities capable of binding to a metal atom and/or ion. While not wishing to be bound by any theory, chelating agents function by making several chemical bonds with metal ions.
  • Exemplary chelating agents include ethylene diamine tetra acetic acid (EDTA), dimercaprol (BAL), dimercaptosuccinic acid (DMSA), 2,3-dimercapto-l-propanesulfonic acid (DMPS), and alpha lipoic acid (ALA), aminophenoxyethane-tetraacetic acid (BAPTA), deferasirox, deferiprone, deferoxamine, diethylene triamine pentaacetic acid (DTPA), dimercapto- propane sulfonate (DMPS), dimercaptosuccinic acid (DMSA), ethylenediamine tetraacetic acid (calcium disodium versante) (CaNa 2 -EDTA), ethylene glycol tetraacetic acid (EGTA), D-penicillamine, methanesulfonic acid, methanephosphonic acid, and mixtures thereof.
  • EDTA ethylene diamine tetra acetic acid
  • BAL dimercap
  • the soluble fixing agent can further include an organic or inorganic additive.
  • the additive is one or more of a flocculent, coagulant, and thickener, to induce flocculation, settling, and/or formation of the precipitated solids.
  • a flocculent coagulant
  • thickener to induce flocculation, settling, and/or formation of the precipitated solids.
  • additives include lime, alum, ferric chloride, ferric sulfate, ferrous sulfate, aluminum sulfate, sodium aluminate, polyaluminum chloride, aluminum trichloride, polyelectrolytes, polyacrylamides, polyacrylate, and the like.
  • the target material-containing stream includes, in addition to the target material, a dissolved valuable product as a dissociated or dissolved cation.
  • the dissolved valuable product is not, under the conditions of the stream, in the form of an oxyanion but occurs as a positively charged metal ion.
  • the soluble fixing agent is added, most of the target material is precipitated while most of the valuable product remains dissolved in the precipitate-containing solution.
  • step 124 at least most of the target material-containing precipitate in the resulting slurry is separated from the aqueous leaching agent (which may be recycled to step 104) to form the separated target material-containing precipitate 128 (which includes most of the target material) and treated stream 140 (which includes most of the leaching agent).
  • the treated stream 140 typically contains no more than about 500 ppm and even more typically no more than about 50 ppm dissolved target material.
  • Residual soluble fixing agent dissolved in the aqueous leaching agent can be removed by adding a salt, such as mineral acid salt (e.g., NaCl) or a halide (e.g., an alkali metal or alkaline earth metal fluoride), or selected oxyanion, such as phosphate or sulfate, to the aqueous leaching agent.
  • a salt such as mineral acid salt (e.g., NaCl) or a halide (e.g., an alkali metal or alkaline earth metal fluoride), or selected oxyanion, such as phosphate or sulfate
  • the soluble rare earth can be oxidized, such as by sparging with oxygen, to a higher oxidation state, optionally followed by pH adjustment to a higher pH, to precipitate the rare earth as an insoluble compound, such as a rare earth oxide.
  • the pH of the aqueous leaching agent is increased, preferably to a pH of at least about pH 7 and even more preferably to a pH of at least about pH 10 to precipitate out the residual soluble fixing agent.
  • the removal of excess soluble fixing agent can occur before or after step 124.
  • the separated target material-containing precipitate 128 is dewatered in step 132 to form the dewatered precipitate 136.
  • dewatering is performed for a time and at a temperature sufficient to remove at least about 50% and even more preferably at least about 75% of the water contained within the separated target material-containing precipitate 128.
  • the separated target material-containing precipitate 128 will be dewatered for a time ranging from about 0.1 to about 24 hours at a temperature ranging from about 0 to about 250 0 C, with about 8 hours at about 100 0 C being even more preferred.
  • the dewatered precipitate 136 is typically a low surface area agglomerate having a high bulk density and low solubility in the aqueous leaching agent.
  • the dewatered material includes at least about 5 wt. %, even more preferably at least about 10 wt. %, and even more preferably at least about 20 wt. % of the target material.
  • the dewatered precipitates 136 contains preferably at least most and even more preferably at least about 85% of the dissolved target material in the target material-containing stream 108 while the treated stream 140 contains typically no more than about 25% of the dissolved target material in the target material-containing stream 108.
  • step 116 is performed using a concentrated and acidic rare earth salt solution added at a relatively rapid rate to produce a precipitate that sequesters more arsenic for a given amount of rare earth than is anticipated based on theoretical "best-case" calculations (which is for a rare earth:arsenic molar ratio of 1 :1).
  • the preferred rare earth salt concentration in the salt solution is preferably at least about 50 g/L, even more preferably from about 100 to about 400 g/L, and even more preferably from about 300 to about 400 g/L.
  • the preferred pH of the salt solution is no more than about pH 2 and even more preferably no more than about pH 0.
  • a particularly preferred formulation includes a solution of cerium in the +3 and/or +4 oxidation state comprising chloride and/or nitrate counter ions.
  • the resulting precipitate has a low density and is gel- like.
  • the precipitate is substantially free of any crystalline phases of arsenic and rare earth solids.
  • rare earth e.g., cerium (III) or (IV)
  • there is typically more than one mole of arsenic more typically at least about 1.1 moles of arsenic, and even more typically at least about 1.25 moles of arsenic.
  • a novel rare earth - target material precipitate is produced.
  • the rare earth is cerium in the +3 oxidation state
  • the target material is arsenic in the +5 oxidation state.
  • the cerium is in the form of cerium chloride (CeCl 3 ) and/or cerium nitrate (Ce(NO 3 ) 3 ).
  • the target material-containing stream 108 commonly has an acidic pH and even more commonly a pH of no more than about pH 5.
  • the pH of the target material-containing stream 108 is raised to a second pH, preferably of at least about pH 6 and even more preferably in the range of about pH 6 to about pH 10.
  • the pH of the target material-containing stream 108 is raised with a strong base, such as an alkali metal hydroxide and group I salt of ammonia, amides, and primary, secondary, tertiary, or quaternary amines, with alkali metal hydroxides being more preferred, and alkali metal hydroxides being even more preferred.
  • the precipitate has a crystal structure different from gasparite.
  • Gasparite (CeAsO 4 ) has a monoclinic space group with a monazite-type structure.
  • the crystal structure of the precipitate belongs to a trigonal space group, such as that of an apparently structurally analogous compound, BiPO 4 (H 2 O) 067 with space group P3 j 21.
  • the PDF card number for trigonal hydrated BiPO 4 is 01-080-0208.
  • the formula of the precipitate is REAsO 4 • (H 2 O) x , where 0 ⁇ X ⁇ 10 and "RE" is a rare earth element.
  • the water molecules are believed to occupy lattice positions, or are believed to be packed, in the crystalline structure.
  • the soluble fixing agent is combined with other arsenic removal agents to form a mixed salt additive.
  • the soluble fixing agent(s) are combined with one or more non-rare-earths having a +3 oxidation state, particularly a transition metal or metal from Groups 13 of the Periodic Table of the Elements, with aluminum or iron in the +3 oxidation state being preferred.
  • the soluble fixing agent is a rare earth metal in the +3 oxidation state, and the soluble fixing agent and non- rare-earth metal are each in the form of water dissociable salts.
  • a double salt mixture is formed by mixing cerium (III) chloride with aluminum (III) chloride.
  • the double salt mixture is formed by mixing lanthanum (III) chloride with aluminum (III) chloride. In another example, the double salt mixture is formed by mixing lanthanum (III) chloride with iron (III) chloride.
  • at least one mole of the non-rare-earth is present for each mole of the rare earth soluble fixing agent. In a more preferred formulation, at least 3 moles of the non-rare-earth are present for each mole of the rare earth soluble fixing agent. In an even more preferred formulation, at least one mole of the non-rare-earth having an oxidation state of +3 is present for each mole of the rare earth soluble fixing agent having an oxidation state of +3. In a yet even more preferred formulation, at least 3 moles of the non-rare-earth having an oxidation state of +3 are present for each mole of the rare earth soluble fixing agent having an oxidation state of +3.
  • the contacting conditions for the mixed salt additive and target material- containing stream 108 depend on the application.
  • the mixed salt additive can have any pH; that is, the mixed salt can have an acidic, neutral, or basic pH.
  • the mixed salt additive has a pH less, that is more acidic, than the target material-containing stream 108 pH. More preferably, the mixed salt additive has an acidic pH, particularly when the pH of the target material-containing stream 108 is basic.
  • the mixed salt additive which is typically a bimetallic lanthanide-based salt solution, is contacted with the target material- containing stream 108 at standard or higher temperature.
  • the pH of the target material- containing stream 108, before and after mixed salt addition can range from about pH 0 to about pH 14.
  • the pH of the mixed solution ranges from about pH 8.5 to about pH 13.5.
  • the mixed salt solution can be contacted with the target material- containing stream over a wide temperature range, preferably from about the freezing point of the stream to about the boiling point of the target material-containing stream.
  • the contacting of the bimetallic lanthanide-based salt and the target material- containing stream 108 produces a precipitate.
  • the precipitate is, for example, believed to be arsenoflorencite-(RE) [(RE)Al 3 (AsO 4 ) 2 (OH) 6 ] when the mixed salt additive comprises a rare earth (“RE") and aluminum (III), and graulichite-(RE) [(RE)Fe 3 (AsO 4 ) 2 (OH) 6 ] when the mixed salt additive comprises a rare earth and iron (III).
  • the separated liquid phase of the precipitate-containing solution 120 retains most, if not all, of the dissolved sulfides, while the target material-containing precipitate 128 contains most, if not all, of the target material, rare earth, and the non-rare-earth(s) contained in the mixed salt additive.
  • the ratio of rare earth to arsenic is at least about 1 :2, which represents a significant reduction in rare earth consumption relative to the configurations noted above in which rare earth arsenates, [REAsO 4 ], are precipitated.
  • the soluble fixing agent is a non-rare-earth salt additive that does not include, or is substantially free of, rare earth metals.
  • the non- rare-earth is particularly a transition metal or metal from Groups 13 of the Periodic Table of the Elements, with aluminum in the +3 oxidation state being preferred.
  • the soluble fixing agent is the form of a non-rare earth (in a +3 oxidation state) salt which substantially dissociates in water under standard conditions (e.g., STP).
  • the contacting conditions for the mixed salt additive and target material- containing stream 108 are not critical.
  • the pH of the salt additive solution can be acidic or basic, the preferred pH is acidic, particularly when the pH of the target material-containing stream 108 is basic.
  • the salt additive solution is contacted with the target material-containing stream 108 at standard (e.g., STP) or higher temperature.
  • the pH of the target material-containing stream 108, before and after salt addition, can range from about pH 0 to about pH 14. More preferably, the pH of the mixed solution ranges from about pH 8.5 to about pH 13.5.
  • the mixed salt solution can be added to the target material-containing stream over a wide temperature range, preferably from about the freezing point to about the boiling point of the target material-containing stream.
  • a precipitate forms from the contacting of the salt additive solution with the target material-containing stream 108.
  • the precipitate is believed to be alarsite [AlAsO 4 ] or mansf ⁇ eldite [AlAsO 4 • H 2 O] when the mixed salt additive comprises aluminum (III), and scorodite [FeAsO 4 ] when the mixed salt additive comprises iron (III).
  • the separated liquid phase of the precipitate-containing solution 120 retains most, if not all, of the dissolved sulfides while most, if not all, of the target material and non-rare-earth metal in the +3 oxidation state are contained in the target material-containing precipitate 128.
  • the target material-containing stream includes dissolved valuable product(s) in a form other than as oxyanions.
  • the stream is subjected to steps 112 (optional), 120, 124 and 128 to form a treated solution and an target material-containing precipitate. At least most, if not all, of the dissolved valuable product(s) remain in solution for recovery by any suitable technique. While not wishing to be bound by any theory, it is believed that soluble and insoluble rare earth fixing agents commonly do not remove metal and metalloid dissociated cations from solution. This can permit metal and metalloid oxyanions to be removed selectively from a solution containing both metal and metalloid oxyanions and dissociated cations.
  • a target material-containing stream 200 is provided.
  • the target material- containing stream 200 can be the stream 108 or any other process stream, byproduct and waste stream from industries such as: mining; metal refining; steel manufacturing; glass manufacturing; metal manufacturing, working and/or processing; chemical and petrochemical production, processing and manufacturing; streams produced from treating and/or remediating a contaminated soil, a wastewater sludge, and the like.
  • Specific examples of target material-bearing streams include pregnant or barren leach solutions and/or other effluent streams, such as contaminated water.
  • the target material concentration in the stream 200 is typically the same as the target material concentration in the target material-containing stream 108.
  • Arsenic for example, can be present in concentrations of more than about 20 ppb arsenic and even more than 1,000 ppb arsenic.
  • the stream 200 can include other dissolved components, such as sulfides and/or sulfates in concentrations noted elsewhere in this disclosure.
  • the pH of the stream 200 can be acidic, neutral, or basic, depending on the application.
  • the stream 200 can also include dissolved solids with a common total dissolved solid ("TDS") level being at least about 5g/L, more commonly at least about 20 g/L, and even more commonly at least about 100 g/L.
  • TDS total dissolved solid
  • the stream 200 is contacted with an insoluble fixing agent to form a target material-loaded insoluble fixing agent 212 and a treated stream 208.
  • an insoluble fixing agent Preferably most, and even more preferably about 75% or more, of the target material is loaded on the insoluble fixing agent.
  • the target material forms a composition with the insoluble fixing agent.
  • the affinity of the insoluble fixing agent for specific target materials is believed to be a function of pH and/or target material concentration.
  • the insoluble fixing agent is commonly used as a particulate in a fixed or fluidized bed and, in certain configurations, may be desirable for use in a stirred tank reactor.
  • the insoluble fixing agent is contained in one or more columns arranged in series or parallel.
  • the insoluble fixing agent includes a flocculent and/or dispersing agent, such as those discussed above, to maintain a substantially uniform particle distribution in the bed.
  • step 204 may be preceded by an oxidation step 112 to oxidize the target material for better target material removal efficiency and/or affinity of the target material for the insoluble fixing agent.
  • the insoluble fixing agent is preferably a rare earth and is in a form that is substantially insoluble in water.
  • the insoluble fixing agent can be, for example, a hydrous or anhydrous rare earth oxide, fluoride, carbonate, fluorocarbonate, or silicate of scandium, yttrium, or a lanthanoid, with an oxide of cerium being preferred and cerium (IV) oxide even more preferred.
  • the insoluble fixing agent is preferably a finely divided solid having an average surface area of between about 25 m 2 /g and about 500 m 2 /g, more preferably between about 70 m 2 /g and about 400 m 2 /g, and even more preferably between about 90 m 2 /g and about 300 m 2 /g.
  • the insoluble fixing agent can be blended with or include other components, such as ion-exchange materials (e.g., synthetic ion exchange resins), porous carbon such as activated carbon, metal oxides (e.g., alumina, silica, silica-alumina, gamma-alumina, activated alumina, acidified alumina, and titania), metal oxides containing labile metal anions (such as aluminum oxy chloride), non-oxide refractories (e.g., titanium nitride, silicon nitride, and silicon carbide), diatomaceous earth, mullite, porous polymeric materials, crystalline aluminosilicates such as zeolites (synthetic or naturally occurring), amorphous silica-alumina, minerals and clays (e.g., bentonite, smectite, kaolin, dolomite, montmorillinite, and their derivatives), ion exchange resins, porous ceramic
  • the insoluble fixing agent may be derived from precipitation of a rare earth metal salt or from thermal decomposition of, for example, a rare earth metal carbonate or oxalate at a temperature preferably between about 100 to about 700 and even more preferably between about 180 and 350 0 C in a furnace in the presence of an oxidant, such as air. Formation of the insoluble fixing agent is further discussed in copending U.S. Application Serial No. 11/932,837, filed October 31, 2007, which is incorporated herein by this reference.
  • the preferred insoluble fixing agent comprises a rare earth compound
  • other fixing agents may be employed. Any fixing agent, whether solid, liquid, gaseous, or gel, that is effective at fixing the target material in solution through precipitation ion exchange, or some other mechanism may be used. Examples of other fixing agents include at least those set forth above.
  • the insoluble fixing agent is an aggregated particulate having a mean surface area of at least about 1 m 2 /g.
  • the aggregated particulates can have a surface area of at least about 5 m 2 /g; in other cases, more than about 10 m 2 /g; and, in still other cases, more than about 25 m 2 /g.
  • the particulates can have a surface area of more than about 70 m 2 /g; in other cases, more than about 85 m 2 /g; in still other cases, more than about 115 m 2 /g; and, in still other cases, more than about 160 m 2 /g.
  • the aggregated particulates can include a polymer binder, such as thermosetting polymers, thermoplastic polymers, elastomeric polymers, cellulosic polymers, and glasses, to at least one of bind, affix, and/or attract the insoluble fixing agent constituents into particulates having one or more of desired size, structure, density, porosity, and fluid properties.
  • the insoluble fixing agent can include one or more flow aids, with or without a binder. Flow aids can improve the fluid dynamics of a fluid over and/or through the insoluble fixing agent to prevent separation of slurry components, prevent the settling of fines, and, in some cases, hold the fixing agent and other components in place.
  • the process 200 operational conditions should be controlled.
  • arsenic is the target material, for example, the insoluble fixing agent
  • the insoluble fixing agent selectively removes at least most of the arsenic while leaving at least most of the valuable product as dissolved (cationic) species in solution.
  • the pH of the target material-containing stream preferably is no more than about pH 6 and even more preferably ranges from about pH 2 to about pH 5 to adsorb both arsenic (V) and arsenic (III).
  • Arsenic (III) sorbs onto the insoluble fixing agent over a broad pH range while arsenic (V) is preferably sorbed by the insoluble fixing agent at lower pH levels.
  • the aqueous solution may contain dissolved solids, with a total dissolved solid content of at least about 50 g/L being typical.
  • the treated stream 208 has, relative to the stream 200, a reduced concentration of the target material. Commonly, most, even more commonly about 75% or more, and even more commonly about 95% or more of the target material in the stream 200 is loaded onto the insoluble fixing agent. In one application, the treated stream 208 preferably has no more than about 1,000 ppm, even more preferably no more than about 500 ppm, even more preferably no more than about 50 ppm, and even more preferably no more than about 5 ppm of the target material.
  • the target material- loaded fixing agent 212 is contacted, in step 216, with a stripping solution, or release agent 238, to unload, or dissolve, preferably most and even more preferably about 95% or more of the agent and form a barren fixing agent 220 (which is recycled to step 204) and a target material-rich stripping solution 224.
  • a stripping solution, or release agent 2308 to unload, or dissolve, preferably most and even more preferably about 95% or more of the agent and form a barren fixing agent 220 (which is recycled to step 204) and a target material-rich stripping solution 224.
  • Any acidic, neutral, or basic stripping solution or release agent may be employed.
  • the desorption process of the rare earth loaded insoluble fixing agent is believed to be a result of a -one or more of: 1) a stronger affinity by the rare earth for the release agent than the sorbed target material or its composition and 2) an upward or downward adjustment of the oxidation state of the rare earth on the surface of the fixing agent 212 and/or of the sorbed target material and/or the sorbed target material- containing oxyanion.
  • the stripping solution is alkaline and comprises a strong base, including the strong bases discussed above. While not wishing to be bound by any theory, it is believed that, at high concentrations, hydroxide ions compete with, and displace, oxyanions from the surface of the insoluble fixing agent.
  • the stripping solution includes a caustic compound in an amount preferably ranging from about 1 to about 15 wt. %, even more preferably from about 1 to about 10 wt. %, and even more preferably from about 2.5 to about 7.5 wt. %, with about 5 wt. % being even more preferred.
  • the preferred pH of the stripping solution 238 is preferably greater (e.g., more basic) than the pH at which the target material was loaded onto the fixing agent 212.
  • the stripping solution 238 pH is preferably at least about pH 10, even more preferably at least about pH 12, and even more preferably at least about pH 14.
  • the (first) stripping solution comprises an oxalate or ethanedioate, which, relative to target material-containing oxyanions, is preferentially sorbed, over a broad pH range, by the insoluble fixing agent.
  • the insoluble fixing agent is contacted with a second stripping solution (not shown) having a preferred pH of at least about pH 9 and even more preferably of at least about pH 11 to desorb oxalate and/or ethanedioate ions in favor of hydroxide ions.
  • a strong base is preferred for the second stripping solution (not shown).
  • the sorbed oxalate and/or ethanedioate anions can be heated to a preferred temperature of at least about 500 0 C to thermally decompose the sorbed oxalate and/or ethanedioate ions and remove them from the insoluble fixing agent.
  • the (first) stripping solution 238 includes a strongly adsorbing exchange oxyanion, such as phosphate, carbonate, silicate, vanadium oxide, or fluoride, to displace the sorbed target material-containing oxyanion.
  • the first stripping solution has a relatively high concentration of the exchange oxyanion.
  • Desorption of the exchange oxyanion is at done at a different (higher) pH and/or exchange oxyanion concentration than the first stripping solution.
  • desorption can be by a second stripping solution (not shown) which includes a strong base and has a lower concentration of the exchange oxyanion than the oxyanion concentration in the first stripping solution.
  • the exchange oxyanion can be thermally decomposed to regenerate the insoluble fixing agent.
  • the exchange oxyanion can be desorbed by oxidation or reduction of the insoluble fixing agent or exchange oxyanion.
  • the stripping solution includes a reductant or reducing agent, such as ferrous ion, lithium aluminum hydride, nascent hydrogen, sodium amalgam, sodium borohydride, stannous ion, sulfite compounds, hydrazine (Wolff-Kishner reduction), zinc-mercury amalgam, diisobutylaluminum hydride, lindlar catalyst, oxalic acid, formic acid, and a carboxylic acid (e.g., a sugar acid, such as ascorbic acid), to reduce the rare earth, sorbed target material, and/or sorbed target material-containing oxyanion.
  • a reductant or reducing agent such as ferrous ion, lithium aluminum hydride, nascent hydrogen, sodium amalgam,
  • surface reduction of the insoluble fixing agent will reduce cerium (IV) to cerium (III), which may interact less strongly with target materials and oxyanions.
  • the pH is increased to desorb the sorbed target material or its oxyanion.
  • the stripping solution includes an oxidant or oxidizing agent, e.g., peroxygen compounds (e.g., peroxide, permanganate, persulfate, etc.), ozone, chlorine, hypochlorite, Fenton's reagent, molecular oxygen, phosphate, sulfur dioxide, and the like, that oxidizes the sorbed target material and/or its oxyanion to a higher oxidation state, e.g., arsenic (III) to arsenic (V), followed by a pH adjustment and a desorption process.
  • oxidant or oxidizing agent e.g., peroxygen compounds (e.g., peroxide, permanganate, persulfate, etc.), ozone, chlorine, hypochlorite, Fenton's reagent, molecular oxygen, phosphate, sulfur dioxide, and the like, that oxidizes the sorbed target material and/or its oxyanion to a higher oxidation state
  • a first concentration of the target material in the target material-containing stream 200 is typically less than a second target material concentration in the target material-rich stripping solution 224.
  • the first concentration of the target material is no more than about 75% of the second concentration and even more commonly no more than about 50% of the second concentration.
  • a first concentration of the arsenic is between about 0.1 mg/L to about 5 g/L
  • the second concentration of arsenic is between about 0.25 g/L and about 7.5 g/L.
  • the target material is removed from the rich stripping solution 224 by a suitable technique to form a target material 232 and a barren stripping solution 236 (which is recycled to step 216). Removal may be effected by any suitable technique including precipitation (such as using a sulfide (for transition metals), an alkaline earth metal carbonate (for fluoride), and a rare earth or iron salt (for arsenic)), adsorption, absorption, electrolysis, cementation, amalgamation, and the like. In one configuration, the target material is precipitated using a soluble rare earth fixing agent as noted above.
  • the target material-containing stream 200 is the target material-containing stream 104 (Fig. IA) and steps 204 and 216 are performed immediately before step 112 or after step 112 and before step 116 to increase the concentration of the target material in the solution prior to step 116.
  • steps 204 and 216 are performed immediately before step 112 or after step 112 and before step 116 to increase the concentration of the target material in the solution prior to step 116. This can provide benefits, such as handling reduced volumes of aqueous solutions in step 116.
  • the soluble fixing agent may not exclusively precipitate arsenic and may depress/remove dissolved metals too.
  • the initial pH of the seven alkaline leach solutions was approximately pH 11, the temperatures of the solutions were approximately 70 to 8O 0 C, and the reaction times were approximately 30 minutes.
  • a first step 200 mL of solution were measured out by weight and transferred into a 400 mL Pyrex beaker. The beaker was then placed on hot/stir plate and heated to 70-80 0 C while being stirred.
  • step three In a second step, 3.44 mL of cerium chloride were measured out, by weight, and poured into the mixing beaker of hot alkaline leach solution. Upon the addition of cerium chloride, a white precipitate formed instantaneously. To ensure that the white precipitate was not cerium carbonate [Ce 2 (CO 3 ) 3 • xH 2 O], step three was performed.
  • Fig. 3 shows that the loading capacity begins to level off at the theoretical capacity of 436 mg/g if cerium arsenate (CeAsO 4 ) was formed, leading one to believe it was formed.
  • Fig. 4 displays that the molar ratio of cerium to arsenic required to bring down the arsenic concentration to less than 50 ppm lies somewhere between a 1 molar and 2 molar ratio. However, at a 2 molar ratio a loading capacity of 217 was achieved.
  • Fig. 5 shows very similar results (essentially double the addition of CeCl 3 ); at a molar ratio between 1 and 2, the dissolved arsenic concentration can be below 50 ppm. This capacity may be improved with a lower molar ratio and tighter pH control.
  • EXAMPLE 2 In another experiment, 40 grams of cerium (IV) dioxide particles were loaded into a 1-inch column giving a bed volume of approximately 50 ml.
  • the cerium dioxide bed had an arsenic-containing process stream [75% As(V), 25% As (III)] flowed through the bed and successfully loaded the media with approximately 44 mg of arsenic per gram CeO 2 or with approximately 1 ,700 mg of arsenic total added to the column.
  • the arsenic loaded cerium dioxide bed had the equivalent of six bed volumes of 5% NaOH solution passed through the bed, at a flow rate of 2 mL/min. This solution released approximately 80% of the 44 mg of arsenic per gram CeO 2 .
  • a test was performed to remove residual rare earth fixing agents from an alkaline leach solution.
  • the product of cerium and arsenic was shown to contain more arsenic than would be anticipated based upon the stoichiometry of gasparite, the anticipated product of cerium and arsenic. Furthermore, the X-ray diffraction pattern suggests that the product is amorphous or nanocrystalline and is consistent with ceria or, possibly, gasparite. The amorphous or nanocrystalline phase not only permits the recycling of process water after arsenic sequestration but does so with a far greater arsenic removal capacity than is observed from other forms of cerium addition, decreasing treatment costs and limiting environmental hazards.
  • the filter cake from the reaction was left over the weekend in plastic weight boats atop a drying oven. Seventy-two hours later, the content of each boat was weighed, and it was determined that the pellets were still very moist (more mass present than was added to the sample as dissolved solids).
  • the semi-dry solids of the samples with 2 mL of cerium salt solution were transferred to a 13O 0 C drying oven for one hour, then analyzed by XRD.
  • XRD results are shown in Fig. 6.
  • XRD results are presented for gasparite (the expected product) and the various systems that were present during the experiments., with "ceria" corresponding to cerium dioxide.
  • the XRD analysis did not detect any crystalline peaks or phases of arsenic and cerium solids in the various systems.
  • the only crystalline material present was identified as either NaCl, NaNO 3 (introduced with the rare earth solutions) or Na 2 SO 4 that was present in the samples prepared from Na 2 SO 4 .
  • the broad diffraction peaks at about 29, 49, and 57 degrees 2-Theta could be indicative of very small particles of ceria or, possibly, gasparite.
  • Fig. 7 shows a plot for arsenic micromoles removed in an "oxidized” system staring with arsenate and a "molecular oxygen sparged" system starting with arsenite, which was subsequently oxidized to arsenate through molecular oxygen sparging.
  • Fig. 7 shows the amount of arsenic consumed by the formation of precipitated solids, plotted as a function of the amount of cerium added.
  • the resultant soluble arsenic concentrations from this experiment can be divided into two groups: samples containing fully oxidized arsenate and sulfate and samples containing arsenite and sulfite that was sparged with molecular oxygen.
  • the oxidation state of the cerium used as the soluble fixing agent had considerably less impact on the efficacy of the process, allowing both Ce(III) and Ce(IV) data to be fit with a single regression line for each test solution.
  • arsenic sequestration with the solids increases in an arsenic to cerium molar ratio of 1 :3, potentially making a product with a stoichiometry of
  • a simulated waste stream solution was prepared with the following components: As (1,200 ppm), F (650 ppm), Fe (120 ppm), S (80 ppm), Si (50 ppm), Ca (35 ppm), Mg (25 ppm), Zn (10 ppm), and less than 10 ppm of Al, K, and Cu.
  • the pH of the solution was titrated down to pH 0.4 with concentrated HCl (12.1 mol/L), and the solution was heated to 7O 0 C.
  • a solution of CeCl 3 (6.3 mL, 1.194 mol/L) was added to the hot solution, and the pH was slowly increased to pH 7.5 by dropwise addition of NaOH (20 wt. %, 6.2 mol/L).
  • the solution was then allowed to age at 7O 0 C under magnetic stirring for 1.5 hours, holding pH at pH 7.5 ⁇ 0.2.
  • the solution was then removed from the heat and allowed to settle undisturbed for 12 to 18 hours.
  • the supernatant was decanted off and saved for ICP-MS analysis of Ce and As.
  • the precipitated solids were centrifuged and washed twice before being filtered through a 0.4 ⁇ m cellulose membrane and washed thoroughly with 500 to 800 mL of de-ionized water. The solids were air-dried and analyzed by X-ray diffraction.
  • Fig. 8 compares the X-Ray Diffraction ("XRD") results for the novel Ce-As compound (shown as trigonal CeAs O 4 ⁇ (H 2 O) x (both experimental and simulated) and gasparite (both experimental and simulated).
  • Fig. 12 compares the XRD results for trigonal CeAs O 4 ⁇ (H 2 O) x (both experimental and simulated) and trigonal BiP O 4 ⁇
  • the solution is aged at 7O 0 C under magnetic stir for 30 minutes. After cooling, the final solution pH is pH 10.4. The solid precipitate was filtered through a 0.4 ⁇ m membrane and dried. ICP-AES analysis of the feed and treated solutions indicates that the arsenic concentration was decreased from 23,800 ppm to 4,300 ppm. This is an 82% removal rate at a capacity of 730 mg arsenic/gram of CeCh.
  • the solution is heated to 7O 0 C under magnetic stir and aged for 60 minutes. After cooling, the final solution pH is pH 11.0. The solid precipitate was centrifuged and washed with water two times, then dried. ICP-AES analysis of the feed and treated solutions indicates that the arsenic concentration was decreased from 23,800 ppm to 2,750 ppm. This is an 89% removal rate at a capacity of 770 mg arsenic/gram of CeCh.
  • Test 1 A number of tests were undertaken to evaluate solution phase cerium ion precipitations. Test 1:
  • the initial pH of the stock solution was pH ⁇ 0-l .
  • the temperature of the stock solution was elevated to 70 0 C.
  • the reaction or residence time was approximately 90 minutes.
  • Step 2 400 mL of synthetic stock solution was measured gravimetrically (402.4Ig) and transferred into a 600 mL Pyrex beaker. The beaker was then placed on hot/stir plate and was heated to 70 0 C while being stirred.
  • Step 3 Enough cerium chloride was added to the stock solution to meet a predetermined molar ratio of cerium to arsenic. For example, to achieve a molar ratio of one ceria mole to one mole of arsenic 5.68 mL of cerium chloride was measure gravimetrically (7.17g) and added to the stirring BHP solution. Upon addition of cerium chloride a yellow/white precipitate formed instantaneously, and the pH dropped due to the normality of the cerium chloride solution being 0.22. The pH was adjusted to approximately 7 using 20% sodium hydroxide.
  • a fluoride free solution gives better arsenic removal when using lower cerium to arsenic molar ratios, in effect giving higher loading capacities.
  • the solids were retained quantitatively, and resuspended in 250 mL of DI water for about 15 minutes.
  • the rinse suspensions were filtered as before for arsenic analysis and the filtered solids were transferred to a weigh boat and left on the benchtop for 4 hours.
  • the filtered solids were weighed and divided into eight portions accounting for the calculated moisture such that each sample was expected to contain 5 g of solids and 3.5 g of moisture (and adsorbed salts).
  • One sample of each arsenic laden solid (As(III) or As(V) was weighed out and transferred to a drying oven for 24 hours, then re-weighed to determine the moisture content.
  • Arsenic-laden ceria samples were weighed out and transferred to 50 mL centrifuge tubes containing extraction solution (Table 8).
  • the solution (except for H2O2) had a 20 hour contact time, but with only occasional mixing via shaking.
  • Hydrogen peroxide contacted the arsenic-laden solids for two hours and was micro waved to 50 deg C to accelerate the reaction.
  • a control sample was prepared wherein the 8.5 g arsenic-laden ceria samples were placed in 45 mL of DI water for the same duration as other extraction tests.
  • the first extraction test used 45 mL of freshly prepared 1 N NaOH. To increase the chances of forcing off arsenic, a 20% NaOH solution was also examined.
  • 10% oxalic acid, 0.25 M phosphate, and 1 g/L carbonate were used as extracting solutions.
  • To test a reduction pathway 5 g of arsenic-laden ceria was added to 45 mL of 0.1 M ascorbic acid. Alternatively an oxidation pathway was considered using 2 mL 30% H2O2 added with 30 mL of DI water
  • the samples were each centrifuged and the supernatant solution was removed and filtered using 0.45 micron syringe filters. The filtered solutions were analyzed for arsenic content.
  • a liter of selenite solution was prepared using 1 g of Na2SeO2. The pH was lowered using 2 mL of 4 M HCl. 40 g of ceria was added to create a slurry that was provided 18 hours to contact. The slurry was filtered and the Se-loaded ceria was retained, weighed, and divided into 50 mL centrifuge tubes for extraction.
  • antimony (III) oxide 100 mg was placed into 1 L of distilled water with 10 mL concentrated HCl, allowed several days to equilibrate, and was filtered through a 0.8 micron polycarbonate membrane to remove undissolved antimony.
  • the liter of antimony solution was contacted with 16 g of ceria powder, which was effective removing antimony from solution, but had too little Sb(III) available to generate a high loading on the surface.
  • the extraction tests revealed little Sb recovery. Even the use of hydrogen peroxide, which would be expected to convert Sb(III) to a less readily adsorbed species of Sb(V), did not result in significant amounts of Sb recovery.
  • Tables 8-11 show the test parameters and results.
  • Table 8 Loading of cerium oxide surface with arsenate and arsenite for the demonstration of arsenic desorbing technologies.
  • Table 9 Loading of cerium oxide surface with arsenate and arsenite for the demonstration of arsenic desorbing technologies.
  • cerium (IV) solutions can be used to remove arsenic from storage pond process waters, and accordingly determine the loading capacity of ceria used. In these trials the storage pond solutions will be diluted with DI water, since previous test work has confirmed that this yields a better arsenic removal capability.
  • the soluble cerium (IV) species used are Ceric Sulfate ⁇ O.I M Ce(SO4)2 and Ceric Nitrate ⁇ Ce(NOs) 4 .
  • the pond solution used has an arsenic split between 27% As (III) and 73% As (V), with a of ph 2. Additional components in the pond solution are presented in Table 12: Additional Sol n Components.
  • Tables 13 and 14 demonstrate that the cerium (IV) solutions have a preferential affinity for the arsenic. When examining the data closer, it appears that some of the other metals fluctuate in concentrations i.e., nickel. According to the dilution scheme used and the limitations of the instrument, there could be up to 15% error in the reported concentrations, explaining some of the fluctuations. Moving onto to table 12, it shows that tests 1 and 2 removed 85% and 74% of the arsenic respectively.
  • the present invention in various embodiments, configurations, or aspects, includes components, methods, processes, systems and/or apparatus substantially as depicted and described herein, including various embodiments, configurations, aspects, subcombinations, and subsets thereof. Those of skill in the art will understand how to make and use the present invention after understanding the present disclosure.
  • the present invention in various embodiments, configurations, and aspects, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments, configurations, or aspects hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease and ⁇ or reducing cost of implementation.

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  • Chemical & Material Sciences (AREA)
  • Water Supply & Treatment (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Removal Of Specific Substances (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Processing Of Solid Wastes (AREA)
  • Water Treatment By Sorption (AREA)

Abstract

La présente invention concerne le retrait d'un ou plusieurs matériaux cibles sélectionnés de différents courants à l'aide d'un agent de fixation contenant des terres rares.
PCT/US2009/064023 2008-11-11 2009-11-11 Retrait de matériaux cibles à l'aide de terres rares WO2010056742A1 (fr)

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CA2743304A CA2743304A1 (fr) 2008-11-11 2009-11-11 Retrait de materiaux cibles a l'aide de terres rares
AU2009314130A AU2009314130B2 (en) 2008-11-11 2009-11-11 Target material removal using rare earth metals
EP09826668.7A EP2364276A4 (fr) 2008-11-11 2009-11-11 Retrait de matériaux cibles à l'aide de terres rares
MX2011004929A MX2011004929A (es) 2008-11-11 2009-11-11 Remocion de material objetivo usando metales de tierra rara.
JP2011535788A JP2012508106A (ja) 2008-11-11 2009-11-11 希土類元素を含む組成物および希土類元素を用いる方法
CN200980154088XA CN102272061A (zh) 2008-11-11 2009-11-11 使用稀土金属除去目标材料
ZA2011/04047A ZA201104047B (en) 2008-11-11 2011-05-31 Target material removal using rare earth metals

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US8337789B2 (en) 2007-05-21 2012-12-25 Orsite Aluminae Inc. Processes for extracting aluminum from aluminous ores
EP2619148A2 (fr) * 2010-09-23 2013-07-31 Molycorp Minerals, LLC Procédé de traitement de l'eau et systèmes de traitement de l'eau destinés à éliminer le tartre et à diminuer la tendance à l'entartrage
JP2013534468A (ja) * 2010-06-11 2013-09-05 モリーコープ ミネラルズ エルエルシー 廃水からの生理活性化合物の改善
JPWO2012023183A1 (ja) * 2010-08-18 2013-10-28 富士通株式会社 計算機管理装置、計算機管理システム及び計算機システム
KR20140022416A (ko) * 2011-04-13 2014-02-24 몰리코프 미네랄스, 엘엘씨 수화 및 수산화 종들의 희토류 제거
CN104437075A (zh) * 2014-10-13 2015-03-25 河北科技大学 利用微波加热催化热解处理挥发性有机气体的方法
US9023301B2 (en) 2012-01-10 2015-05-05 Orbite Aluminae Inc. Processes for treating red mud
EP2786737A4 (fr) * 2011-11-29 2015-10-28 Shibano Tetsuya Agent réducteur contenant du borohydrure de sodium
US9181603B2 (en) 2012-03-29 2015-11-10 Orbite Technologies Inc. Processes for treating fly ashes
US9260767B2 (en) 2011-03-18 2016-02-16 Orbite Technologies Inc. Processes for recovering rare earth elements from aluminum-bearing materials
US9290828B2 (en) 2012-07-12 2016-03-22 Orbite Technologies Inc. Processes for preparing titanium oxide and various other products
US9353425B2 (en) 2012-09-26 2016-05-31 Orbite Technologies Inc. Processes for preparing alumina and magnesium chloride by HCl leaching of various materials
US9382600B2 (en) 2011-09-16 2016-07-05 Orbite Technologies Inc. Processes for preparing alumina and various other products
US9410227B2 (en) 2011-05-04 2016-08-09 Orbite Technologies Inc. Processes for recovering rare earth elements from various ores
US9534274B2 (en) 2012-11-14 2017-01-03 Orbite Technologies Inc. Methods for purifying aluminium ions
EP3201138A4 (fr) * 2014-10-03 2018-03-28 Chemtreat, Inc. Compositions et procédés pour le retrait sélectif d'anions
US11512368B2 (en) 2017-04-06 2022-11-29 Montanuniversität Leoben Method for removing fluoride from a zinc-containing solution or suspension, defluoridated zinc sulfate solution and use thereof, and method for producing zinc and hydrogen fluoride or hydrofluoric acid

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US8337789B2 (en) 2007-05-21 2012-12-25 Orsite Aluminae Inc. Processes for extracting aluminum from aluminous ores
US8597600B2 (en) 2007-05-21 2013-12-03 Orbite Aluminae Inc. Processes for extracting aluminum from aluminous ores
JP2013534468A (ja) * 2010-06-11 2013-09-05 モリーコープ ミネラルズ エルエルシー 廃水からの生理活性化合物の改善
JPWO2012023183A1 (ja) * 2010-08-18 2013-10-28 富士通株式会社 計算機管理装置、計算機管理システム及び計算機システム
JP5549733B2 (ja) * 2010-08-18 2014-07-16 富士通株式会社 計算機管理装置、計算機管理システム及び計算機システム
EP2619148A2 (fr) * 2010-09-23 2013-07-31 Molycorp Minerals, LLC Procédé de traitement de l'eau et systèmes de traitement de l'eau destinés à éliminer le tartre et à diminuer la tendance à l'entartrage
EP2619148A4 (fr) * 2010-09-23 2014-04-02 Molycorp Minerals Llc Procédé de traitement de l'eau et systèmes de traitement de l'eau destinés à éliminer le tartre et à diminuer la tendance à l'entartrage
US9260767B2 (en) 2011-03-18 2016-02-16 Orbite Technologies Inc. Processes for recovering rare earth elements from aluminum-bearing materials
US9945009B2 (en) 2011-03-18 2018-04-17 Orbite Technologies Inc. Processes for recovering rare earth elements from aluminum-bearing materials
KR20140022416A (ko) * 2011-04-13 2014-02-24 몰리코프 미네랄스, 엘엘씨 수화 및 수산화 종들의 희토류 제거
JP2018051557A (ja) * 2011-04-13 2018-04-05 セキュア ナチュラル リソーシズ エルエルシーＳｅｃｕｒｅ Ｎａｔｕｒａｌ Ｒｅｓｏｕｒｃｅｓ Ｌｌｃ 水和化および水酸基を含む化学種の希土類元素の除去
JP2014518538A (ja) * 2011-04-13 2014-07-31 モリーコープ ミネラルズ エルエルシー 水和化および水酸基を含む化学種の希土類元素の除去
KR102015961B1 (ko) 2011-04-13 2019-08-29 시큐어 네이처 리소시즈 엘엘씨 수화 및 수산화 종들의 희토류 제거
US9410227B2 (en) 2011-05-04 2016-08-09 Orbite Technologies Inc. Processes for recovering rare earth elements from various ores
US10174402B2 (en) 2011-09-16 2019-01-08 Orbite Technologies Inc. Processes for preparing alumina and various other products
US9382600B2 (en) 2011-09-16 2016-07-05 Orbite Technologies Inc. Processes for preparing alumina and various other products
EP2786737A4 (fr) * 2011-11-29 2015-10-28 Shibano Tetsuya Agent réducteur contenant du borohydrure de sodium
US9023301B2 (en) 2012-01-10 2015-05-05 Orbite Aluminae Inc. Processes for treating red mud
US9556500B2 (en) 2012-01-10 2017-01-31 Orbite Technologies Inc. Processes for treating red mud
US9181603B2 (en) 2012-03-29 2015-11-10 Orbite Technologies Inc. Processes for treating fly ashes
US9290828B2 (en) 2012-07-12 2016-03-22 Orbite Technologies Inc. Processes for preparing titanium oxide and various other products
US9353425B2 (en) 2012-09-26 2016-05-31 Orbite Technologies Inc. Processes for preparing alumina and magnesium chloride by HCl leaching of various materials
US9534274B2 (en) 2012-11-14 2017-01-03 Orbite Technologies Inc. Methods for purifying aluminium ions
EP3201138A4 (fr) * 2014-10-03 2018-03-28 Chemtreat, Inc. Compositions et procédés pour le retrait sélectif d'anions
CN104437075A (zh) * 2014-10-13 2015-03-25 河北科技大学 利用微波加热催化热解处理挥发性有机气体的方法
US11512368B2 (en) 2017-04-06 2022-11-29 Montanuniversität Leoben Method for removing fluoride from a zinc-containing solution or suspension, defluoridated zinc sulfate solution and use thereof, and method for producing zinc and hydrogen fluoride or hydrofluoric acid

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